Optic neuropathy in Hodgkin's disease.

Hodgkin's disease is a rare cause of infiltrative optic neuropathy, which typically evolves late in the disease course. We managed an unusual case of isolated optic neuropathy in a 21-year-old man occurring during clinical remission from Hodgkin's disease. Radiotherapy and treatment with high-dose systemic corticosteroids resulted in dramatic improvement in vision. Even without other evidence of recurrent disease, acute-onset optic neuropathy in a patient with a history of a lymphoproliferative disorder should raise the question of a reemergence of the malignancy.


Pulmonary vascular amyloidosis in aged dogs. A new form of spontaneously occurring amyloidosis derived from apolipoprotein AI.

The N-terminus of a mutant form of apolipoprotein AI [apoAI] has previously been shown to be the subunit protein of amyloid fibrils in a human kindred with a form of familial amyloid polyneuropathy (FAP, type III) and in a recently reported kindred with a form of non-neuropathic hereditary amyloidosis. In this study, we demonstrate by amino-acid sequence analysis, that a form of vascular amyloidosis occurring in the lungs of aged dogs is derived from a N-terminal fragment of apoAI and that no amino acid substitution is present in this confirmed sequence. This represents the first documentation of apoAI as a precursor for a form of amyloidosis in animals, and provides the first documentation of apoAI as a precursor for amyloid fibrils in a form of age-associated ("senile") amyloidosis. Secondary structure prediction analysis of the N-terminal regions of normal human and dog apoAI indicated a propensity for beta-pleated sheet conformation, and thus amyloidogenesis, in 40 and 45% of the respective sequences. These results suggest that apoAI (like transthyretin) may serve as an amyloid precursor protein for both familial and senile forms of amyloidosis. ApoAI should, therefore, be considered as a potential amyloid precursor when forms of human senile amyloidosis of unknown origin are evaluated.


Interleukin-4 may contribute to the abundant T-cell reaction and paucity of neoplastic B cells in T-cell-rich B-cell lymphomas.

T-cell-rich B-cell lymphomas (TCRBCLs) are diffuse lymphomas that contain a minority of large neoplastic B cells amidst a majority of non-neoplastic T cells and numerous histiocytes, an unusually pronounced reactive component not seen in most diffuse large B-cell lymphomas (DLBCLs). This reaction may be influenced by various cytokines secreted by lymphoma or reactive cells; therefore, expression of interleukin (IL)-1 beta, IL-2, IL-4, IL-6, and IL-9 was evaluated immunohistochemically on paraffin-embedded sections of 18 TCRBCLs and was compared with that of 15 DLBCLs containing a minority of reactive T cells and to that of seven reactive lymph nodes. Moderate to intense expression of IL-4 was detected in variable numbers of tumor cells and in numerous histiocytes in 16 TCRBCLs. In contrast, intense IL-4 expression in numerous histiocytes was observed in only one of 15 DLBCLs with few T cells. In four other DLBCLs and three reactive nodes, moderate to intense staining for IL-4 was noted only in rare large transformed cells or in occasional histiocytes. Except for one IL-1 beta positive and another IL-9 positive TCRBCL, there was no marking or weak staining only with other cytokine antibodies in the neoplastic and reactive cases studied. The expression of IL-4 in most TCRBCLs, but not in other DLBCLs or in reactive nodes, suggests that this cytokine is one factor involved in the pathobiology of the abundant T-cell reaction and, perhaps, contributes to the paucity of neoplastic B cells in TCRBCLs.


Synaptophysin expression in "ependymal tumors" induced by ethyl-nitrosourea in rats.

Synaptophysin expression was studied in seven "ependymomas" induced by transplacental administration of ethyl-nitrosourea in rats. In all the cases, strong positivity for synaptophysin was found on tumor cells. This finding supports previous studies suggesting that ENU-induced brain tumors considered to be ependymal neoplasms, are, in fact, primitive neuroectodermal tumors.


The rat testicular artery: a model of spontaneous aneurysmal-like structure formation.

The straight spermatic and highly convoluted testicular arteries were studied by light microscopy in adult and aging normotensive (NT) and spontaneously hypertensive (SHR) rats. In younger rats, on the internal part of bends of the testicular artery, areas lacking the media similar to classical cerebral arterial medial defects were observed. At the same location, in other bends, structurally defective areas (SDA) constituted by or including medial defects but also lacking the internal elastic lamina and which in some cases evaginated, were present. Structurally defective areas were less numerous in SHR than in NT rats at 6 months, suggesting that intrinsic differences may exist between rat strains. In contrast, in old rats, the number of SDA was higher in hypertensive than in normotensive rats, supporting the role of hemodynamics in SDA formation. With age, SDA enlarged in both rat strains, and most of them became structurally similar to aneurysms, ie, lacking the internal elastic lamina and medial cells and with a dilated lumen, supporting the view that medial defects are sites of aneurysmal structure development. In hypertensive rats, fibrin and lipid deposits occurred within these aneurysmal-like structures. In the straight part of the spermatic artery no such structural modifications occurred, suggesting that either hemodynamics and/or structural development, both dependent on arterial geometry, are determinant in SDA formation. The results are discussed in view of the use of the rat testicular artery as a possible model of the formation of spontaneous aneurysmal-like structures relevant to cerebral aneurysms.


Detection of laminin receptor mRNA in human cancer cell lines and colorectal tissues by in situ hybridization.

The 67-kd high-affinity laminin receptor (67 LR) is a gene product whose expression appears to be associated with the invasive and metastatic phenotype of a variety of human cancer cells. Northern blot hybridization has been routinely used to quantify the level of 67 LR mRNA from total cellular RNA extracts of homogenized tissue specimens or in vitro grown cell populations. This technique is useful to assess the average expression of the 67 LR mRNA of a particular sample but does not provide information about expression in specific cell types nor about heterogeneity of expression from cell to cell. In this study, we analyzed the expression of 67 LR mRNA in four human cancer cell lines with varying degrees of expression of 67 LR protein (renal cancer A-704, breast carcinoma MCF-7/4 and MCF-7/7, and pancreatic cancer Panc-1) using in situ hybridization performed with 67 LR riboprobes. Total cellular RNA was simultaneously extracted from the cell lines and hybridized on Northern blots with a 67 LR cDNA probe to assess the validity of the mRNA detection by in situ hybridization. Sixty-seven LR mRNA expression was higher in Panc-1 and MCF-7/4 cells than in MCF-7/7 and renal carcinoma A-704. There was a direct correlation (R2 = 0.88) between the in situ hybridization analysis and the mRNA levels detected by Northern blot analysis. The in situ hybridization method showed a heterogeneous expression of the 67 LR mRNA in the four cell lines with different subpopulations of cells showing a range from negative to high levels of the message. Sixteen freshly frozen human colorectal tissues (seven adenocarcinomas, five matched normal mucosae, and four adenomas) were also analyzed by in situ hybridization. The 67 LR mRNA was localized in normal and neoplastic epithelial cells. Adenocarcinoma cells showed a 1.6- to 5-fold higher expression (P < 0.02 according to the Wilcoxon-Mann-Whitney test) than did epithelial colonic cells from normal mucosae or adenomas. The signal tended to be stronger in poorly differentiated carcinomas and carcinomas with metastases than in moderately differentiated and nonmetastatic tumors. We conclude that the high expression of 67 LR mRNA in colorectal tumors is due to an increased production by tumor cells. Furthermore, in situ hybridization is an effective method to detect the expression of LR mRNA in cultured cell lines as well as in frozen tissue sections.


Differential permeability of the blood-brain barrier in experimental brain metastases produced by human neoplasms implanted into nude mice.

This study clarified whether and when the blood-brain barrier in experimental brain metastases is impaired by using hydrosoluble sodium fluorescein (MW 376) as a blood-brain barrier function indicator. Cells from eight human tumor lines (four melanomas, two breast carcinomas, one colon carcinoma, and one renal carcinoma) were inoculated into the internal carotid artery of nude mice. Brain metastases at different stages of development were sampled and the permeability of the blood-brain barrier around the metastases determined. Histologic examination showed two patterns of tumor growth. In the first, tumor cells formed isolated, well-defined nodules in the parenchyma of the brain. In lesions smaller than 0.2 mm2, the blood-brain barrier was intact. In the second, small diffuse nests of tumor cells were distributed throughout the brain parenchyma. The blood-brain barrier was intact until the small tumor cell colonies coalesced to form large tumor masses. These results suggest that the permeability of the blood-brain barrier varies among different experimental brain metastases and that its function is related to the growth pattern and size of the lesions.


Expression of a chimeric helix-loop-helix gene, Id-SCL, in K562 human leukemic cells is associated with nuclear segmentation.

We have designed a chimeric gene, Id-SCL, in which the 3' helix-loop-helix encoding portion of the presumptive oncogene SCL/tal is joined to the 5' coding portion of Id, an inhibitory helix-loop-helix gene. The predicted protein product of this chimeric gene contains the helix-loop-helix dimerization domain of SCL/tal, but, lacking a basic DNA binding domain, is predicted to have the inhibitory function of the Id product. Expression of the Id-SCL fusion gene in stably transfected K562 cells reproducibly resulted in nuclear segmentation and depressed growth rates; both of these phenotypic effects demonstrated a dosage dependence on the levels of Id-SCL mRNA and protein expressed in the various clones. Electron microscopy of cells expressing high levels of Id-SCL mRNA showed a significant increase in cytoplasmic perinuclear thin filaments and diminution of marginal heterochromatin in the nuclei. No other changes in hematopoietic differentiation status were observed in association with Id-SCL expression. Expression of intact Id and SCL/tal genes, as well as deletion mutants of Id and SCL/tal, independently transfected into K562 cells, indicated that the nuclear segmentation effect is dependent on the presence of a protein possessing a helix-loop-helix domain but lacking a basic domain. Our studies suggest that the balance of transcriptional inhibitory and stimulatory helix-loop-helix proteins in cells may be important determinants of proliferation and of structural organization within cells.


Transplant arteriosclerosis in a rat aortic model.

Transplant arteriosclerosis (TA) has emerged as an obstacle to the long-term survival of transplanted organs, especially cardiac transplants. The animal models that have been used to study TA have not been fully characterized with regard to features such as the time course of cell proliferation and the sequence of cell types arriving in the developing intimal lesion. We present a model of TA based on a transplanted segment of abdominal aorta that helps address these questions. Two strains of rats (PVG x DA) underwent orthotopic aortic transplantation without immunosuppression and were killed at 14, 20, 40, and 60 days after transplantation. The within-strain control group displayed minimal evidence of cellular rejection with minimal to absent intimal lesions. In contrast, the allograft group showed a linearly increasing intimal lesion, up through 60 days after transplantation. The mechanism of intimal thickening was by an increase in cell number at the earlier time points with the later deposition of extracellular matrix. The early intimal lesion consisted mostly of mononuclear inflammatory cells (45%) with gradually increasing presence of smooth muscle cells (SMC) in the intima between 20 and 60 days. Conversely, the media showed gradual infiltration by macrophage-type cells with virtual loss of all SMC from the media by 40 days. The proliferative index showed a peak of 6% and 8% at 20 days in both the intima and media, respectively, and was preceded by the presence of macrophages. In fact, most of the proliferating cells at the earlier time points were either monocytes/macrophages, or were immediately adjacent to monocyte-/macrophage-rich regions. This straight artery segment model of transplant arteriosclerosis provides an easily quantifiable system in which the effects of different interventions (e.g., immunosuppressive regimens) can be tested.


The genesis of the senile plaque. Further evidence in support of its neuronal origin.

Senile plaques are among the most conspicuous neuropathologic changes found in the brains of elderly individuals and patients with Alzheimer's disease (AD). The origin of the amyloid beta protein (A beta P) that accumulates in senile plaques continues to be highly controversial. Recently, using quantitative immunohistochemistry and computerized image analysis, we obtained evidence that at least a subset of early ("diffuse") senile plaques originate from neurons. In the current investigation, we employed monoclonal antibodies to A beta P and the same computerized methodology to examine in further detail the quantitative patterns of A beta P deposition in diffuse plaques in a population of intellectually intact elderly individuals. The presence of neurocentric concentration gradients of A beta P accumulation was confirmed in this study. Most significantly, this was the most predominant pattern of early amyloid deposition in the population studied. The highest concentration of A beta P was centered around neuronal cell bodies or their processes, and occasionally along neuronal plasma membranes. Computerized images showed patterns that can be interpreted as a pathogenetic sequence ranging from initial neurogenic concentration gradients centered around one single neuron to larger deposits (diffuse plaques) composed of several "anastomosing" gradients involving several adjacent neurons. It is proposed that the described very early deposits constitute the initial stage in the development of the senile plaque. Although this study does not fully prove that the accumulated A beta P is synthesized in the neuron or neuronal process it surrounds, the images herein presented suggest that neurons are the initial nidus of plaque formation.


Integrin distributions in renal cell carcinomas of various grades of malignancy.

We studied 41 renal cell carcinomas, classified according to histologic grades G1 through G3, by indirect immunofluorescence microscopy using a panel of monoclonal antibodies (MAb) against various integrin subunits, and the basement membrane (BM) components laminin and collagen type IV. Selected cases also were immunostained using the avidin-biotin-complex method. The alpha 3 and beta 1 integrin subunits were detected in tumor cells of all the carcinomas. All G1 carcinomas, like normal tubular epithelial cells, expressed the alpha 6 subunit, whereas it was lacking in 20% and 40% of G2 and G3 carcinomas, respectively. Furthermore, when alpha 6 was expressed, a lack of basally polarized organization of the subunit, coupled with disorganization of the BM components, correlated with histologic grade. Another feature that appeared to characterize the more anaplastic tumors was their high level (80%) of the alpha v subunit expression as compared with its absence in the G1 carcinomas. Stromal myofibroblasts, identified by double-labeling with anti-myosin, were often characterized by the expression of the alpha 1, alpha 3, alpha 5 and beta 1 subunits. These results indicate that changes in integrin expression in renal cell carcinomas may be correlated with their degree of histologic malignancy.


Cystitis induced by infection with the Lyme disease spirochete, Borrelia burgdorferi, in mice.

Previous studies have demonstrated that the urinary bladder is a consistent source for isolating the Lyme disease spirochete, Borrelia burgdorferi, from both experimentally infected and naturally exposed rodents. We examined histopathologic changes in the urinary bladder of different types of rodents experimentally infected with Lyme spirochetes, including BALB/c mice (Mus musculus), nude mice (M. musculus), white-footed mice (Peromyscus leucopus), and grasshopper mice (Onychomys leucogaster). Animals were inoculated intraperitoneally, subcutaneously, or intranasally with low-passaged spirochetes, high-passaged spirochetes, or phosphate-buffered saline. At various times after inoculation, animals were killed and approximately one-half of each urinary bladder and kidney were cultured separately in BSK-II medium while the other half of each organ was prepared for histologic examination. Spirochetes were cultured from the urinary bladder of all 35 mice inoculated with low-passaged spirochetes while we were unable to isolate spirochetes from any kidneys of the same mice. The pathologic changes observed most frequently in the urinary bladder of the infected mice were the presence of lymphoid aggregates, vascular changes, including an increase in the number of vessels and thickening of the vessel walls, and perivascular infiltrates. Our results demonstrate that nearly all individuals (93%) of the four types of mice examined had a cystitis associated with spirochetal infection.


Anthracyclines selectively decrease alpha cardiac actin mRNA abundance in the rat heart.

Anthracyclines are widely used antineoplastic agents, but possess a major side effect of congestive cardiomyopathy. Previously we showed a selective effect of the most commonly used anthracycline, doxorubicin, on decreasing alpha-cardiac (alpha c) actin mRNA abundance in the rat heart. The current studies examined the effects of several anthracyclines (doxorubicin, daunorubicin, and epirubicin) to determine if doxorubicin's previously reported effect on alpha c actin mRNA abundance is: 1) a property shared by other cardiotoxic anthracyclines; 2) selective when compared with a wider spectrum of contractile protein and muscle-specific mRNAs; and 3) related to the characteristic ultrastructural alterations, such as loss of myofilaments, seen in anthracycline-induced cardiomyopathy. Results showed a major selective effect of doxorubicin, daunorubicin, and epirubicin on decreasing alpha c actin mRNA abundance when compared with other contractile protein and muscle-specific mRNAs. In addition, ultrastructural examination of myocardium showed contractile alterations, including loss of myofilaments. These results suggest that decreased expression of selected cardiac genes may relate to the molecular mechanism of clinical anthracycline-induced cardiomyopathy.


Efficacy of monoclonal antibody against human recombinant tumor necrosis factor in E. coli-challenged swine.

Monoclonal antibody against human tumor necrosis factor alpha (TNF MAb) prevents death induced by intravenous gram-negative bacteria or lipopolysaccharide (LPS) in primates. Although these studies have demonstrated that TNF plays a prominent role in the development of lethal septic shock, exploration of dose-response relationships and possible mechanisms of protection have been limited. We addressed these questions in a series of experiments conducted in E. coli-challenged pigs. First, we determined that TNF MAb neutralized the cytotoxic activity found in septic pig plasma and in culture media from pig monocytes incubated with LPS. Second, we demonstrated that pretreatment with TNF MAb promotes survival, in a dose-dependent fashion, in an otherwise lethal E. coli bacteremic pig model. The results of the survival study highly correlate (r = 0.96, P < 0.01) the presence of TNF in the circulation with mortality. In an additional series of physiologic monitoring experiments designed to delineate possible mechanisms of protection, the authors demonstrate that TNF MAb pretreatment abrogates the prolonged leukopenia, thrombocytopenia, and microvascular leakiness resulting from intravenous bacterial challenge and maintains arterial blood pressure while diminishing pulmonary edema. These findings may provide a mechanism whereby neutralization of TNF systemically affords protection against the lethal sequelae of bacteremia.


Different patterns of macrophage infiltration into allogeneic-murine and xenogeneic-human neoplasms growing in nude mice.

This study determined the distribution pattern of tumor-associated macrophages (TAM) in murine and human neoplasms growing subcutaneously in nude mice. Seven different human neoplasms (cancers of the breast, kidney, colon, prostate, lung, and skin, and a melanoma) and five different murine neoplasms (carcinomas of the lung, colon, and kidney, melanoma, and fibrosarcoma) were injected into nude mice. The murine tumors also were injected into syngeneic mice. Tumor-associated macrophages in small and large tumors were studied immunohistochemically by the use of several antibodies, including the macrophage-specific F4/80. The pattern of TAM distribution differed between mouse and human tumors. Regardless of histologic classification, TAM were uniformly distributed throughout all the murine neoplasms growing in syngeneic or nude mice. In the human neoplasms, TAM were found on the periphery of the lesions and in association with fibrous septae. The distribution of TAM in murine and human tumors was associated with a pattern of vascularization as determined by antibodies to basement membrane collagen type IV. Because the pattern of TAM distribution in neoplasms influences their antitumor activity, the data question the validity of the nude mouse model for the study of macrophage infiltration into human neoplasms.


A recessive defect in lymphocyte or granulocyte function caused by an integrated transgene.

A line of transgenic mice has been identified with a recessive defect in lymphocyte or granulocyte function, presumably as a result of insertional mutagenesis by the integrated transgene. Transgenic mice homozygous for the transgene integrant showed nearly complete absence of lymphocytes in peripheral lymph nodes and Peyer's patches, a severely diminished thymus medulla, and a greatly enlarged spleen. These animals also developed a syndrome characterized by granulocyte and mononuclear infiltrates in numerous tissues, including skin, liver, and lung, and immunoglobulin deposits in kidney glomeruli. Lung infiltrates were specifically localized around large blood vessels and bronchi, accompanied in some cases by destruction of arterial walls. The light scatter profile of spleen lymphocytes suggested an extremely high percentage of blast cells. Because tissue development and morphology appears to be normal in all other tissues observed, the genetic lesion appears to specifically affect the regulation of lymphocyte or granulocyte activation.


Bereavement support groups for school-age children: theory, intervention, and case example.

Children's bereavement support groups can provide useful surrogate support for families when a parent dies, and may contribute new social meaning for this traumatic event. Theories and techniques for intervention in such groups are presented and their application illustrated via a clinical case history. Results indicate that categorization of children's bereavement should be abandoned in favor of conceptualization in terms of prior adaptation processes.


Detachment revisited: the child's reconstruction of a dead parent.

During the year following a parent's death, children in a community-based sample were found to have developed an inner construction of the dead parent. This continued, though altered, relationship appeared to facilitate their coping with the loss and with accompanying changes in their lives. Implications for understanding the bereavement process and for interventions focusing on detachment are discussed.


Childhood parental death and depression in adulthood: roles of surviving parent and family environment.

Among adults who experienced a childhood parental death, measures of depression were influenced by interactions with the surviving parent and by the nature of the family environment after the death. Individuals describing their surviving parent as empathic and warm, and as promoting autonomy, were less likely to report depressive experiences than were others. Less opportunity for participating in the mourning process was also associated with greater risk for depression.


Parental death in childhood: perceived vulnerability, and adult depression and anxiety.

College students who had experienced the death of a parent during their childhoods perceived themselves as more vulnerable to future losses than did a nonbereaved control group. Perceived vulnerability to loss was identified as a better predictor of adult anxiety and depression than was the early loss itself. Perceived vulnerability to loss is thus implicated in the development of adult psychopathology associated with early loss.


Victimization and traumatic injuries among the homeless: associations with alcohol, drug, and mental problems.

Data from a 1987 survey of 1,260 homeless adults in New York City show that mental problems and substance dependence were significantly linked to beating and sexual assault among women and to several types of injury and victimization among men. The extremely high rates of victimization and injury underscore a need for greater attention to the safety and welfare of homeless people.


Early life experiences and residential stability: a ten-year perspective on sheltered care.

The effects of early family losses and disruptions on the ability of seriously mentally disabled individuals to achieve stable living arrangements were investigated. Factors found to predict instability were early losses, early disruptions, psychological symptoms, and youth. Among factors found to predict stability were increased age and a diagnosis of schizophrenia.


Recent trauma in psychiatric outpatients.

Psychiatric clinic outpatients were screened for recent traumatic events, and post-traumatic symptomatology was evaluated in those reporting occurrence of one or more events within the two years prior to screening. Clear symptoms of post-traumatic stress disorder were revealed in 18% of the reporting patients, and the distribution of diagnoses was found to be different in the trauma-reporting group than it was in a comparison diagnostic group.


Marital satisfaction among parents of the severely mentally ill living in the community.

Factors influencing marital satisfaction among 131 parents of adult offspring with severe mental illness were explored. Those found to be most predictive of marital satisfaction were parents' ability to comfort one another, parents' gender, number of offspring, family income, and interpersonal sensitivity. Implications of these findings for practical and policy approaches to preventive intervention are discussed.


Temperament and adjustment in young adulthood: a 15-year longitudinal analysis.

The relationship between easy/difficult temperament and adjustment from middle adolescence to young adulthood was examined. Cluster analysis revealed four groups of individuals via composite temperament scores over three points of measurement. Multivariate analyses indicated that extremely difficult temperament was associated with poorer psychosocial functioning in childhood and young adulthood.


Long-term effectiveness of a group program for caregivers of frail elderly veterans.

Long-term results of an evaluation of a multicomponent support-group program for spouses caring for frail elderly veterans indicated that participants experienced significant reductions in subjective burden. As compared to those of the control group, caregivers' perceptions of their husbands' health improved significantly from pretest to one year, while perceptions of their husbands' functioning on measures of instrumental daily activities showed significantly less deterioration in the period from pretest to posttest.


Locus of control as a mediator of negative divorce-related events and adjustment problems in children.

Beliefs about whether locus of control mediates the relationship between negative divorce-related events and children's adjustment were explored in a group of 78 children and their primary residential parents. In the children's self-reports of adjustment, locus of control was found to be a partial mediator in the relationship. Analyses of the parents' reports of the children's adjustment did not support a mediational model.


Impact on children of abduction by a parent: a review of the literature.

It is estimated that 350,000 children are abducted by members of their families annually. A review of the published research reveals that little is known about the impact of this traumatic event on the children. Factors reported to affect their functioning after recovery by the searching parent are identified, and implications for further research are suggested.


Functional somatic symptoms: a cross-ethnic comparison.

Type, distribution, and comorbidity of functional somatic symptoms were examined in four community samples, three Hispanic and one non-Hispanic white. Important intergroup and intragroup differences between Hispanic and non-Hispanic white groups were identified. Of the four groups, Puerto Rican respondents reported the highest level of somatic symptoms; this finding was apparently independent of sociodemographic factors.


Family functions and children's postdivorce adjustment.

Data on school-age children of divorced parents were examined to determine which dimensions of family dynamics were most associated with the children's socioemotional adjustment. Those factors found to be most significant were family roles, behavior control, and affective involvement, as well as children's reaction to and insight into the divorce, and conflict in the home after the divorce. Implications for parent education and early intervention are discussed.


Self-structure in borderline personality disorder.

Self-structural theory is applied to the interpersonal aspects of borderline personality disorder. The notion of interpersonal contrasting, a cognitive maneuver, is introduced to account for the sharp changes between divergent self-states characteristic of the disorder. The theory and three prototypical self-states are illustrated with data from a borderline patient by means of a procedure derived from the theory.


Hearing results from endolymphatic sac surgery.

This report examines the effect of the endolymphatic shunt on hearing. The study group was drawn from 101 shunt operations for intractable vertigo between 1983 and 1987. Thirty ears met criteria for diagnosis, level of preoperative hearing impairment, and length of follow-up. The control group consisted of 30 ears with symptoms severe enough to prompt recommendations for shunt surgery, but the patients either opted against surgery or improved. The results were analyzed using the 1985 AAO-HNS reporting criteria. When looking at worst postoperative (or worst scores after 2 years of follow-up in controls) compared to worst preoperative (or worst scores in the first 6 months of presentation in controls), we found no significant difference between the study group (average loss of 9 dB pure-tone average [PTA] and 16% speech discrimination [SD]) as compared to the control group (average loss of 3 dB PTA and 10% SD). However, when using the first and last audiograms for the control group, there was a statistically significant difference as compared to the worst preoperative and postoperative scores in the shunt group. Using the first and last scores, the control group had a better outcome (PTA improved 2 dB, SD score dropped 5%). There was no significant difference between groups for percentage of patients whose hearing improved, remained the same, or worsened. In conclusion, the endolymphatic shunt operation did not significantly effect the long-term hearing results.


Aberration of the tissue collagenase system in association with otosclerosis.

Studies of aural and other body tissues suggest that otosclerosis represents the local manifestation of a general disorder of connective tissue. In particular, collagen abnormalities have been described. We have undertaken a pilot study of the in vivo messenger RNA (mRNA) transcription for procollagenase (precursor of collagenase), as well as for stromelysin and tissue inhibitor of metalloprotease (TIMP), an activator and a specific inhibitor of tissue collagenase activity, respectively. Human skin from individuals with surgically confirmed otosclerosis was compared to skin from their family members (clinically positive and clinically negative) and from unrelated normal controls. Preliminary data indicate that on average there are significantly lower levels of mRNA production for stromelysin among individuals with otosclerosis as compared to all others tested. Similar trends were demonstrated for TIMP and procollagenase, although these did not achieve statistical significance. In addition to suggesting a pathogenetic mechanism for the development of the disease, these data could serve as the basis of possible confirmatory tests for early diagnosis of otosclerosis and as a method for evaluating the genotype of offspring of affected individuals prior to their age of clinical manifestation. This could translate into the application of prophylactic treatment regimens in the future. The proposed abnormalities also suggest candidate genes for otosclerosis.


Transcochlear transtentorial approach for removal of large cerebellopontine angle meningiomas.

Meningiomas of the cerebellopontine angle (CPA) most often arise from the posterior surface of the petrous pyramid and may extend along the dura to involve the tentorium. Petroclival meningiomas often involve Meckel's cavity and the tentorium. It is impossible to completely remove these large lesions with extension to the supratentorial region by conventional surgical approaches to the CPA such as the suboccipital, middle fossa, or translabyrinthine routes. If total tumor resection is not accomplished, recurrence inevitably follows. A transcochlear approach and actual excision of a large portion of the tentorium allows wide exposure to these large CPA and petroclival meningiomas with supratentorial extension. Thirty-three CPA meningiomas were reviewed from 1976 to 1991. Fourteen patients had tumor extension not only into Meckel's cavity but to the supratentorial region. Ten patients had complete tumor removal, whereas subtotal removal was associated with cavernous sinus invasion. The surgical technique is described in detail with accompanying illustrations. Preoperative symptoms, medical imaging scans, results, and complications are discussed.


Labyrinthotomy with streptomycin infusion: early results of a multicenter study. The LSI Multicenter Study Group.

Early results for hearing and vertigo are reported for 47 labyrinthotomies with streptomycin infusion (LSI) by 13 coinvestigator-surgeons. Sixty-eight percent of patients had worse hearing after surgery (10 dB or 15% word recognition). Patients with a preoperative pure-tone average better than or equal to 40 dB appeared to suffer less postoperative hearing loss than those with a greater preoperative deficit. Severe to profound postoperative hearing loss was experienced by 27 patients (57%), all of whom had preoperative pure-tone averages worse than 40 dB. Opening the endolymphatic space was associated with a deleterious effect on hearing. Because of persistent vertigo, 17 percent of patients required a secondary procedure during the period of observation. These early results indicate that LSI is associated with a significant risk of postoperative hearing loss. Of the 13 coinvestigator-surgeons, four have stopped using LSI, while one considers his results satisfactory. The remaining surgeons have taken an intermediate position and feel it is useful in selected cases. Longer follow-up is required to judge the efficacy of LSI for controlling vertigo. We are currently studying these long-term results.


Retrolabyrinthine transtentorial approach to lesions of the anterior cerebellopontine angle.

Various surgical approaches to the cerebellopontine angle have been used for removal of acoustic neuromas. A retrolabyrinthine transtentorial approach has been developed that allows (1) access to the anterior cerebellopontine angle and all portions of the basilar artery, (2) extra dural retraction of the lateral sinus and cerebellum while avoiding the vein of Labbé, and (3) preservation of hearing. This approach allows good exposure of tumor and accurate visualization of cranial nerves. To avoid complications, control of spinal fluid is mandatory and great care must be taken to avoid injury of the cranial nerves. The retrolabyrinthine or translabyrinthine transtentorial approach enables skilled neurosurgeons and neurotologists to gain access to lesions that are located in areas difficult to approach.


Differential diagnosis of virus-like particles in the human inner ear.

The entire endolymphatic duct and sac as well as the vestibular epithelia were obtained from four patients with Meniere's disease during translabyrinthine (TL) eighth nerve section and from 12 patients undergoing TL resection of acoustic schwannomas. After these specimens were processed for routine transmission electron microscopy (TEM), they were studied for morphologic evidence of viral infection. Although no virus particles were identified, numerous regularly occurring cell components and artifacts were found to morphologically mimic viruses. An atlas of these structures is presented.


Aspartame and dizziness: preliminary results of a prospective, nonblinded, prevalence and attempted cross-over study.

Aspartame is a low-calorie food sweetener recently approved by the FDA for general human consumption. One of us (AJG) treated a patient whose symptoms of episodic vertigo and continuous unsteadiness resolved upon ceasing aspartame intake. A literature review revealed that although dizziness has been associated with aspartame intake, no systematic study of the problem exists. As an initial attempt to ascertain the prevalence of aspartame-related dizziness in an otolaryngologic clinic, we elected to study prospectively all patients entering with the complaint of vertigo by means of a standardized questionnaire. Those patients determined to consume aspartame were further studied in a nonblinded manner to see if aspartame intake could be correlated to symptomatology. A cross-over limb was also attempted, but no patient would participate. This presentation details the case history of the propositus patient and the preliminary results of the currently ongoing prospective study.


System identification of perilymphatic fistula in an animal model.

An acute animal model has been developed in the chinchilla for the study of perilymphatic fistulas. Micropunctures were made in three sites to simulate bony, round window, and oval window fistulas. The eye movements in response to pressure applied to the external auditory canal were recorded after micropuncture induction and in preoperative controls. The main pressure stimulus was a pseudorandom binary sequence (PRBS) that rapidly changed between plus and minus 200 mm of water. The PRBS stimulus, with its wide frequency bandwidth, produced responses clearly above the preoperative baseline in 78 percent of the runs. The response was better between 0.5 and 3.3 Hz than it was below 0.5 Hz. The direction of horizontal eye movement was toward the side of the fistula with positive pressure applied in 92 percent of the runs. Vertical eye movements were also observed. The ratio of vertical eye displacement to horizontal eye displacement depended upon the site of the micropuncture induction. Thus, such a ratio measurement may be clinically useful in the noninvasive localization of perilymphatic fistulas in humans.


Evaluations of 3M/House single-channel and nucleus multichannel cochlear implants.

3M/House single-channel (n = 158) and Nucleus multichannel (n = 71) adult cochlear implant users were surveyed about their devices. In comparison to the 3M/House users, the Nucleus users reported better speech and environmental sounds perception and more hours of daily use. However, Nucleus users also were more likely to report that the expense of upkeep and frequent movement of external parts of their implants were problems. On average, users in both groups were satisfied and felt that their implants had positively affected their lifestyle, enjoyment of social events, and employability. Differences between groups regarding these variables were not found. Multiple regression indicated that the users' ratings of the effects of their implants on speech perception, environmental sounds perception, enjoyment of social events, and lifestyle were all statistically significant predictors of satisfaction. It was concluded that the majority of the users in either group thought their devices provided real-world benefits.


Reconstruction of the radical mastoid.

Open cavity techniques (radical mastoidectomy, canal wall down tympanomastoidectomy, modified radical mastoidectomy) are well established surgical procedures for the treatment of chronic otitis media. Despite their effectiveness in exteriorizing cholesteatoma, they are associated with a 20 to 60 percent incidence of persistent intermittent drainage. In an effort to eliminate this problem, we have employed a Palva flap and medial graft technique to reconstruct the mastoid cavity and middle ear space in those patients with chronically draining ears. Between 1987 and 1990, 28 patients underwent this procedure. Twenty-six of these (93%) had complete obliteration of the mastoid cavity and successful tympanic membrane reconstruction. Two of 28 (7%) had a persistent tympanic membrane perforation and intermittent drainage following their surgery. Based on these results, this procedure is effective in eliminating intermittent drainage associated with the open cavity techniques. The indications for this procedure, the specifics of the surgical technique, and the postoperative results are discussed.


Geniculate ganglion: anatomic study with surgical implications.

The geniculate ganglion and adjacent segments of the facial nerve were dissected in 11 human temporal bones to study the extent and distribution of ganglion cells. A histologic basis for the use of geniculate ganglionectomy as the treatment for geniculate neuralgia was sought. In 9 of 11 specimens (81.8%), the ganglion cell bodies appeared to be aggregated at the apex of the genu close to the origin of the greater superficial petrosal nerve. The mean ratio of the width of the ganglion cell cluster to the width of the facial nerve trunk at the level of the genu was 0.4. In two specimens, significant anatomic variation was present. One specimen showed extension of cell bodies into the labyrinthine segment of the facial nerve; another specimen showed a single ganglion cell in the region of the genu. These findings lead us to postulate that geniculate ganglionectomy may be ineffective as the sole treatment for certain cases of geniculate neuralgia, and that nervus intermedius section may also be required to achieve a more complete deafferentation.


Rhinorrhea after neurotologic surgery.

Rhinorrhea after neurotologic surgery may be indicative of a cerebrospinal fluid (CSF) leak or may be secondary to autonomic dysfunction as a result of injury to preganglionic parasympathetic fibers. Differentiation between these two conditions is essential because undetected CSF rhinorrhea may lead to meningitis and death.


Menière's disease in congenital nephrogenic diabetes insipidus: report of two twins.

Two cases, twins, affected by congenital nephrogenic diabetes insipidus (CNDI) with a high daily volume of dilute urine excretion and periods of compensatory high levels of antidiuretic hormone (ADH) simultaneously developed a fluctuating Menière-type hearing loss. It is well known that the kidney and the cochlea are linked by structural and anatomic characteristics, as well as by the physiologic mechanism of electrolytes and fluid regulation. The patients herein described seem to be paradoxical, because they suffered from hydropic hearing loss despite the pathophysiologic mechanism of CNDI and the possible role played by ADH in water regulation in the inner ear. The consequences on Menière's disease of the different therapeutic regimens followed by the two CNDI patients are discussed. To our knowledge these are the first cases of CNDI with Menière's disease described in the literature.


Very far-advanced otosclerosis.

The term very far-advanced otosclerosis is proposed to indicate otosclerotic patients with both bone and air conduction thresholds nonmeasurable on a standard clinical audiometer (blank audiogram). Three of these patients have undergone stapedotomy with satisfactory results. This confirms that cochlear implantation is not the best treatment for all profoundly deaf patients at least with implants available today. Some of the patients with a blank audiogram are better off with exploratory tympanotomy and stapedotomy.


Computed tomography and enamel thickness of maxillary molars of Plio-Pleistocene hominids from Sterkfontein, Swartkrans, and Kromdraai (South Africa): An exploratory study.

This paper is one in a series which explores the possibility of using the non-destructive CT technique to identify patterns in tooth enamel distribution and structure of hominid molars from Plio-Pleistocene sites in South Africa, notably Swartkrans, Sterkfontein, and Kromdraai. Whereas previous investigators have emphasised gross differences in absolute and relative or average enamel thickness between hominid taxa, the present study highlights differences in enamel thickness over functionally significant regions of the crown. Differences in the distribution of enamel in A. robustus, A. africanus, and Homo sp. are identified through the use of bivariate and multivariate analyses, and are interpreted in terms of dietary regimes.


Congenital syphilis in the past: slaves at Newton Plantation, Barbados, West Indies.

Hutchinson's incisors and Moon's molars are specific lesions of congenital syphilis. The extensive but fragmentary clinical literature on these conditions describes reduced dimensions and thin enamel in the permanent incisors and first molars, crowding and infolding of the first molar cusps, notching of the upper incisors, and apical hypoplasias of the permanent canines. A Barbados slave cemetery (ca. 1660-1820 AD) includes three individuals with these features, suggesting a frequency at birth of congenital syphilis in the population approaching 10%. These three cases show triple the frequency of all hypoplasias and more than seven times the frequency of pitting hypoplasia present in the remainder of the series. The recognizable congenital syphilis cases account for much of the remarkably high frequency of hypoplasias in the series as a whole. We infer that syphilis contributed substantially to morbidity, infant mortality, and infertility in this population. Presence or absence of congenital syphilis may account for much of the variability in health and mortality seen among nineteenth century African-American populations.


Demography of the Hadza, an increasing and high density population of Savanna foragers.

This is a report on the demography of the Hadza, a population of East African hunter-gatherers. In it, we describe the results of a census, and our estimation of age structure, survivorship, mean age of women at childbearing, number of live children, total population size and density, and rate of change since 1967. We show that relevant measures fit closely the stable population model North 6 chosen by Dyson to represent Hadza demography in the 1960s. We compare aspects of Hadza demography with surrounding non-Hadza and with the !Kung. Among other things, we find that the Hadza have a higher population density, higher fertility, and a faster population growth rate than do the !Kung. These demographic differences are consistent with our expectations, which were based on differences in the costs and benefits of foraging in the two regions. We also show that Hadza demographic parameters display remarkable consistency over the past 20 years. Since neighboring populations have been encroaching on the area used by the Hadza, and Hadza foragers have been subject to interludes of externally imposed settlement, this consistency is surprising. We discuss some of the implications.


Evaluation of lead concentrations in 18th-century Omaha Indian skeletons using ICP-MS.

The analysis of skeletal remains of Omaha Indians buried between AD 1780 and 1820 indicated that lead was incorporated in cortical bone. The diagenetic or biogenetic origin of the lead was evaluated by examination of lead isotope ratios of the bones and artifacts, and comparison of lead concentrations in burial soils with those of the bones. The isotopic values of the lead artifacts demonstrate that the lead was mined in the Missouri region. Although the isotope ratios in the bones are not identical with that from the lead artifacts, there is a strong relationship between them. This finding indicates that the lead in the bone was at least partly derived from the artifacts. Because lead artifacts rarely accompanied the burials but lead was ubiquitous in the bones, we suggest a biogenetic origin for the lead. There is also the possibility that some of the lead may have been derived from pigments applied to the corpse during mortuary ritual.


Carbon and nitrogen stable isotopic signatures of human dietary change in the Georgia Bight.

Measurement of carbon and nitrogen stable isotope ratios (delta 13C and delta 15N) in samples of human bone collagen (n = 93) from a temporal series of four prehistoric (early preagricultural, late preagricultural, early agricultural, late agricultural) and two historic (early contact, late contact) periods from the Georgia Bight, a continental embayment on the southeastern U.S. Atlantic coast, reveals a general temporal trend for less negative delta 13C values and less positive delta 15N values. This trend reflects a concomitant decrease in emphasis on marine resources and increased reliance on C4-based resources, especially maize. This dietary reorientation is most apparent for the early agricultural sample (AD 1150-1300), coinciding with the Mississippian fluorescence in the eastern United States. There is, however, a shift toward the use of C3 (non-maize) foods during the last prehistoric period (AD 1300-1450), which is likely related to environmental stress and social disruption. A heavier use of maize and terrestrial resources in general after the establishment of mission centers on barrier islands is indicated. A reduced dietary breadth during the mission period may have contributed to the extinction of these populations in the eighteenth century.


New species of bushbaby from the middle Miocene of Maboko Island, Kenya.

A mandible recovered from ca. 15 million year old deposits of Maboko Island, Kenya, represents the first bushbaby known from the middle Miocene. The specimen is from a new species of Komba, a genus previously known from early Miocene occurrences in western Kenya and northeastern Uganda. Komba is revised, with emended diagnoses proposed for the genus, type-species, and referred species. Komba sp. nov. is distinguished by its larger size and differences of molar cusp acuity, buccal cingulum expression, and mental foramen configuration. Contrary to previous opinion, species of Komba probably diverged prior to the last common ancestor of extant Galaginae, and it is unlikely that they represent early stages of living bushbaby species lineages. Although contemporary Progalago is widely regarded as a galagine, aspects of upper molar, lower premolar, and mandibular corpus morphology indicate that it is more closely related to lorisines. Unlike the greater success currently enjoyed by bushbabies, lorisines were more diverse and almost as abundant as galagines in the early Miocene of eastern Africa.


Estimation of age structure in anthropological demography.

The past decade has produced considerable debate over the feasibility of paleodemographic research, with much attention focusing on the question of reliability of age estimates. We show here that in cases where age is estimated rather than known, the traditional method of assigning individuals to age classes will produce biased estimates of age structure. We demonstrate the effect of this bias both mathematically and by computer simulation, and show how a more appropriate method from the fisheries literature (the "iterated age length key") can be used to estimate age structure. Because it is often the case that ages are also estimated for extant groups, we suggest that our results are relevant to the general field of anthropological demography, and that it is time for us to improve the statistical basis for age structure estimation. We further suggest that the oft noted paucity of older individuals in skeletal collections is a simple result of the use of inappropriate methods of age estimation, and that this problem can be rectified in the future by using maximum likelihood estimates of life table or hazard functions incorporating the uncertainty of age estimates.


Association of phospholipase C-delta with a highly enriched preparation of canine sarcolemma.

Myocardial synthesis of phosphatidylinositol 4,5-bisphosphate (PIP2) is highly compartmentalized in the sarcolemmal membrane. Sarcolemmal vesicles contain endogenous phospholipase C (PLC), but the identity of sarcolemmal PLC and its relationship to soluble PLC have not been determined previously. Sarcolemmal and cytosolic PLC were prepared from canine myocardium and characterized by DEAE-cellulose chromatography and by immunoblotting with monoclonal and polyclonal antibodies to isoenzymes of PLC (PLC beta, PLC gamma, and PLC delta). DEAE-cellulose chromatography resolved two forms of cytosolic PLC that were identified as an 85-kDa form of PLC delta and a 145-kDa form of PLC gamma. In contrast, DEAE-cellulose chromatography resolved a single form of sarcolemmal PLC that was identified as an 85-kDa form of PLC delta. These data demonstrate that PLC gamma and PLC delta are expressed in canine myocardium and that an 85-kDa form of PLC delta is selectively associated with sites of PIP2 synthesis in a highly enriched preparation of sarcolemma. These data do not exclude the existence of additional isoenzymes of sarcolemmal PLC that may have been removed during isolation of sarcolemmal membranes.


Oxygenation-activated K fluxes in trout red blood cells.

The effect of oxygenation on the dissipative fluxes of K in trout red blood cells has been determined. Unidirectional influx under low oxygen tension (PO2 = 1 kPa) was 0.56 +/- 0.07 mmol.l-1 packed cells.h-1. Within a few minutes of equilibration with high oxygen tension (PO2 = 120 kPa), influx was increased 14-fold, and this was associated with a progressive loss of KCl and a cell shrinkage. K influx progressively declined over the following 3 h to levels close to those characteristic of cells at low oxygen tension. Replacement of medium Cl by NO3- or methane sulfonate inhibited the stimulation due to high oxygen as did furosemide and low extracellular pH. The oxygenation-stimulated influx was highly volume sensitive, being increased by up to 100% by osmotic swelling and decreased by osmotic shrinkage. By contrast, the small influx under low oxygen tension was unaffected by either Cl replacement or by shrinkage and increased only with extreme swelling. Thus high oxygen tension activated a Cl-dependent and furosemide-sensitive K flux. Once activated, the mechanism was rapidly deactivated on transfer back to low oxygen tension but slowly deactivated when maintained at high PO2. The oxygenation-stimulated flux mechanism promotes a rapid and more complete volume regulatory decrease than in cells at low oxygen tension.


Effect of fatigue on rate of isometric force development in mouse fast- and slow-twitch muscles.

Changes in the rate of isometric force development with fatigue were measured in vitro (25 degrees C) using mouse soleus and extensor digitorum longus (EDL) muscles. Muscles were fatigued using 30 tetanic contractions. Rate of force development was determined from the rate constant of an exponential curve fitted to the rising force phase of a tetanus. For both muscles, when the intertetanus interval was 3 s, maximum isometric force and relaxation rate were significantly reduced in the final tetanus relative to the values in the first tetanus. Rate of force development in soleus muscles transiently increased and then decreased a small amount. The final rate was 92.7 +/- 3.3% (n = 4) of the initial rate. In contrast, the rate of force development in EDL muscles increased to 133.7 +/- 3.3% (n = 4) of the initial rate. This increased rate was evident from the second tetanus of the series, was fully established after 5 tetani, and the magnitude of the increase in rate was inversely proportional to intertetanus interval and was independent of presumed energy expenditure. The enhanced rate decayed with a time constant of 14.3 +/- 2.0 s and was independent of presumed energy expenditure. Most of these observations can be explained by the effects of P(i) on cross bridge kinetics. Other possible mechanisms, involving more rapid activation, are also suggested.


Effects of intracellular ions on interleukin-1 beta production by lipopolysaccharide-activated human monocytes.

Following the observation that interleukin 1 beta (IL-1 beta) production in lipopolysaccharide (LPS)activated monocytes increases in concert with a rise in intracellular pH (pHi), the role of ion transport in IL-1 beta production was investigated. The amiloride analogue 5-(N-ethyl-N-isopropyl)amiloride (EIPA), an inhibitor of the Na(+)-H+ antiporter, inhibited extracellular IL-1 beta. The replacement of Na+ in the culture medium with sucrose or choline chloride also prevented monocyte activation. The sodium ionophore monensin, in doses from 100 pM to 1 microM, potentiated LPS-stimulated extracellular IL-1 beta when compared with LPS alone. In the absence of LPS activation, monensin by itself at 10 nM stimulated IL-1 beta production to 63%. EIPA at 10 microM inhibited the Na+ influx, the rise in pHi, and intra- and extracellular IL-1 beta production in activated monocytes; this inhibition was reversed by 10 nM monensin. In the absence of bicarbonate, or in the presence of 10 microM 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, the pHi of activated monocytes and the total protein synthesis did not change, but the production of IL-1 beta was inhibited. The data suggest that the stimulated influx of Na+ via the Na(+)-H+ antiporter regulates both pHi and IL-1 beta production in LPS-activated monocytes. The requirement for bicarbonate indicates an additional mechanism(s), separate from the modulation of pHi and intracellular Na+.


Chemical modification of Ca(2+)-activated potassium channels of GH3 anterior pituitary cells.

The effects of amino group specific reagents were examined on single, large-conductance, Ca(2+)-activated, K+ channels in excised membrane patches from GH3 cells. The reagents used include trinitrobenzene sulfonic acid, 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid and its 4-acetamido derivative, and sulfophenyl-isothiocyanate. These reagents react covalently with peptide terminal amino groups and the epsilon amino groups of lysine residues, thereby removing positive charge. Internal application of 0.1-1.0 mM reagent to inside-out patches irreversibly increases channel open probability. Single-channel conductance and voltage sensitivity are not affected by modification. Analysis of channel openings and closures shows that the increase in open probability is predominantly due to the loss of long-duration closures of the channel; however, the lengths of long-duration openings are increased. After the modification in the presence of Ca2+ was performed, the channel open probability remains large, regardless of the internal Ca2+ concentration. Transitions among several open and closed states of the modified channel are present in the absence of Ca2+, suggesting that many state transitions are not directly dependent on Ca2+ binding or dissociation.


Delayed shortening and shrinkage of cochlear outer hair cells.

Slow shortening of cochlear outer hair cells has been speculated to modify cochlear sensitivity. Tetanic electrical field stimulation of isolated outer hair cells from guinea pigs shortened the cells for 2-3 min. Electrical stimulation reduced cell length and volume (-13.5 +/- 1.5 and -37.3 +/- 3.0% of initial values, respectively, n = 16) and decreased the intracellular Cl- concentration. Cytochalasin B (100 microM) inhibited electrical stimulation-induced shortening but not volume reduction. The following chemicals or manipulations inhibited the responses: 10 microM furosemide, 0.1 mM 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), 1 mM anthracene-9-carboxylic acid (AC9), 25 mM tetraethylammonium, 2.3 microM charybdotoxin (ChTX), 250 nM omega-conotoxin, and Ca(2+)-free medium. These findings suggest that both electrical stimulation-induced shortening and shrinkage of outer hair cells result not only from an actin-mediated contractile force, but also from Cl- efflux through furosemide-, DIDS-, and AC9-sensitive Cl- channels, and K+ efflux through ChTX-sensitive K+ channels.


Interaction of TPA and ultraviolet B radiation in regulation of ODC gene expression in rat keratinocytes.

Ultraviolet B radiation (UVB) and phorbol esters are known to promote tumor formation in skin; however, the interaction between UVB and phorbol esters in the regulation of gene expression remains incompletely understood. To define the interaction of UVB and phorbol esters in the control of keratinocyte gene expression, we have studied the effects of the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) and UVB on the regulation of ornithine decarboxylase (ODC) gene expression in a rat keratinocyte cell line. Both UVB and TPA alone increased ODC activity and induced the expression of the ODC gene. The combination of UVB and TPA produced a further increment in ODC gene expression at 12 h, but UVB markedly attenuated the TPA induction of ODC mRNA transcripts at 3 h. Protein synthesis inhibition with cycloheximide also induced ODC mRNA transcripts, but did not eliminate the further induction of ODC gene expression by UVB or TPA. No changes in actin gene expression following exposure to TPA/UVB were detected in the same experiments. UVB and TPA alone or in combination had no effect on the transcriptional activity of an ODC-chloramphenicol acetyltransferase fusion gene in transfected rat keratinocytes. The results of these studies suggest a complex posttranscriptional interaction of phorbol esters and UVB in the control of keratinocyte gene expression.


Erythrocyte K-Cl cotransport: properties and regulation.

Erythrocytes possess a Cl-dependent, Na-independent K transport system cotransporting K and Cl in a 1:1 stoichiometry that is membrane potential independent. This K-Cl cotransporter is stimulated by cell swelling, acidification, Mg depletion, and thiol modification. Cell shrinkage, elevation of cellular divalent ions, thiol alkylation, phosphatase inhibitors, and derivatives of certain loop diuretics and stilbenes are inhibitory. Thus regulation of K-Cl cotransport at the membrane and cytoplasmic levels is highly complex. Basal K-Cl cotransport decreases with cellular maturation, whereas its modes of stimulation and inhibition are variable between species. The physiological inactivation appears to be prevented in low-K animal erythrocytes. In certain human hemoglobinopathies, K-Cl cotransport may be the cause of cellular dehydration and volume decrease. K-Cl cotransport occurs also in nonerythroid cells, such as in epithelial and liver cells of other species. At the threshold of molecular characterization, this comprehensive review places our present understanding of the mechanisms modulating K-Cl cotransport physiologically and pathophysiologically into kinetic and thermodynamic perspectives.


Potentiation of twitch contraction in guinea pig ureter by sodium vanadate.

The effect of sodium vanadate on action potential and twitch contraction of guinea pig ureter was studied and compared with that of ouabain, elevated K+, low temperature, and a Ca agonist (BAY K 8644), which can be expected to exert certain comparative effects. Sodium vanadate markedly potentiated twitch contraction. Potentiation by vanadate was associated with marked prolongation of relaxation time. Sodium vanadate caused only slight depolarization of the membrane but marked changes in action potential. The duration of action potential was prolonged and the number of oscillatory spike potentials increased. These effects were different from those of other treatments. It is concluded that prolongation of action potential and the increase in the number of spikes are the main cause of potentiation of twitch contraction by sodium vanadate. In addition, inhibition of Ca pump activity of the smooth muscle membrane system by vanadate might also be involved in potentiation of twitch contraction.


Kinetics of nucleocytoplasmic Ca2+ transients in DDT1 MF-2 smooth muscle cells.

The free calcium concentrations in the nucleus ([Ca2+]n) and in the cytoplasm ([Ca2+]c) of cultured DDT1 MF-2 smooth muscle cells were estimated using the fluorescent dye indo-1. With the use of confocal microscopy, line scans were made during the onset and the differential rise of the Ca2+ signal elicited by the agonists histamine and ATP. The results confirm our earlier findings that in these cells [Ca2+]n at rest was lower than [Ca2+]c. The present experiments show that this gradient over the nuclear envelope was also preserved in Ca(2+)-free solution containing 2 mM EGTA, underlining the selective barrier function of the nuclear envelope. During stimulation with histamine, an early Ca2+ rise in the vicinity of the nuclear envelope was found in contrast to the delayed Ca2+ rise 2 microns away on both sides of the envelope. This suggests the release of Ca2+ stored in the envelope and the perinuclear sarcoplasmic reticulum. The time course for reaching a uniform Ca2+ concentration ([Ca2+]u = [Ca2+]n = [Ca2+]c) in the nuclear and cytosolic compartment varied with the agonist used for stimulation and was dependent on the external Ca2+ concentration. The value of this uniform Ca2+ concentration itself was, however, independent of the type of stimulation. After reaching [Ca2+]u, a further rise occurred with [Ca2+]n becoming larger than [Ca2+]c. It is postulated that a critical Ca2+ concentration must be reached to induce this differential Ca2+ rise by releasing Ca2+ from an intranuclear Ca2+ store.


Membrane currents in a calcitonin-secreting human C cell line.

The whole cell version of the patch-clamp technique was used to identify and characterize voltage-gated Ca2+, Na+, and K+ currents in the calcitonin-secreting human thyroid TT cell line. Ca2+ current consisted of a single low-voltage-activated rapidly inactivating component. The current was one-half maximally activated at a potential of -27 mV, while steady-state voltage-dependent inactivation was one-half complete at -51 mV. The Ca2+ current inactivated with a voltage-dependent time constant that reached a minimum of 16 ms at potentials positive to -15 mV. Deactivation kinetics could also be fit with a single voltage-dependent time constant of approximately 2 ms at -80 mV. Replacing Ca2+ with Ba2+ reduced the maximum current by 18 +/- 5% (n = 6). The dihydropyridine Ca2+ agonist (-)BAY K 8644 did not affect the Ca2+ current, but 50 microM Ni2+ reduced it by 81 +/- 0.8% (n = 5). TT cells also possessed tetrodotoxin-sensitive voltage-gated Na+ channels and tetraethylammonium-sensitive delayed rectifier type K+ currents. These results indicate that TT cells possess membrane currents necessary for the generation of action potentials. T-type Ca2+ channels are the sole pathway for voltage-dependent Ca2+ entry into these cells and may couple electrical activity to calcitonin secretion.


Effect of cytochalasin D on the actin cytoskeleton of the toad bladder epithelial cell.

Cytochalasins are widely used to determine the role of actin in cellular processes. Their actions include capping of the barbed end of actin filaments as well as dimer formation, nucleation, and polymerization. We determined the effect of cytochalasin D (CD) on F-actin in the toad urinary bladder, an epithelium in which vasopressin depolymerizes F-actin. At a low concentration (0.25 microM), CD depolymerized F-actin in the unstimulated cell; at higher concentrations, there was a progressive reduction of depolymerization until actual polymerization was seen. Vasopressin plus CD produced no greater depolymerization than vasopressin alone, suggesting that CD and vasopressin act to a large extent on the same pool of F-actin. CD plus vasopressin also enhanced the fusion rate of aggrephores compared with vasopressin alone, indicating that intact actin filaments retard aggrephore fusion. Despite the increase in aggrephore fusion, water flow was not enhanced by CD, confirming previous reports that intact actin filaments are required for water channel emergence or stabilization in the apical membrane. Vasopressin plus 1 microM CD produced a striking increase in microvillar length, direct evidence of the polymerizing action of CD in the cell.


In vivo estimation of lactose hydrolysis in premature infants using a dual stable tracer technique.

To investigate their putative capacity for lactose digestion, primed continuous orogastric infusions of [1-13C]glucose and D-[1-13C]lactose were administered on consecutive days to five premature infants (30-31 wk gestation, 15-32 days of age), who were fed by orogastric infusions of human milk or formula. By monitoring the plateau isotopic enrichment of plasma glucose using isotopomers containing the entire derivatized glucose molecule or C-2 through C-6, we were able to distinguish label appearing in the peripheral circulation deriving from unmetabolized glucose from that arising from recycled or fermented glucose (or lactose). Isotopic enrichment of the C-1 of glucose, corrected for recycling, was then calculated during each tracer infusion, and the fraction of dietary lactose subjected to in vivo hydrolysis was estimated from these values and the respective tracer infusion rates, assuming similar absorptive and metabolic fates of labeled glucose arising from either tracer. This fraction averaged 1.02 +/- 0.16 (SD), suggesting that lactose digestion is efficient by 34-wk postconceptional age.


Heated dorsal hand vein sampling for metabolic studies: a reappraisal.

The purpose of the current study was to determine the accuracy of a given heated dorsal hand vein (HDHV) measurement in predicting a simultaneous arterial measurement and to validate this technique for use in stable isotope studies. Twenty catheterizations of the femoral artery, femoral vein, and a dorsal hand vein were performed in 13 healthy male subjects. Simultaneous blood samples were obtained from all three sites during primed continuous infusions of L-[1-13C]leucine (Leu) and L-[ring-2H5]phenylalanine (Phe) in the postabsorptive state, with or without intravenous glucose infusion. Relationships were examined by linear regression analysis, with 95% prediction intervals for femoral arterial values determined using the HDHV-derived values as independent variable. Glucose concentrations and isotopic enrichments of ketoisocaproate (KIC), Leu, and Phe were similar in HDHV- and arterial-derived blood, with slopes between 0.9414 and 1.0008, intercepts not different from zero, and r2 values of 0.7613 or greater (P < 0.05). Intercepts for KIC, Leu, and Phe concentrations all were different from zero (P < 0.05), and slopes ranged between 0.7560 and 0.8625. For each analysis the HDHV sample correlated better with the femoral arterial sample than with the femoral venous sample. These data support the use of HDHV sampling as a surrogate for direct arterial sampling but document significant limitations in the technique.


Muscle glucose transport, GLUT-4 content, and degree of exercise training in obese Zucker rats.

The effects of high (HI)- and low (LI)-intensity exercise training were examined on insulin-stimulated 3-O-methyl-D-glucose (3-MG) transport and concentration of insulin-regulatable glucose transporter protein (GLUT-4) in the red (fast-twitch oxidative) and white (fast-twitch glycolytic) quadriceps of the obese Zucker rat. Sedentary obese (SED) and lean (LN) Zucker rats were used as controls. 3-MG transport was determined during hindlimb perfusion in the presence of 8 mM 3-MG, 2 mM mannitol, 0.3 mM pyruvate, and 0.5 mU/ml insulin. HI and LI rats displayed greater rates of red quadriceps 3-MG transport and GLUT-4 concentrations than SED rats. No significant differences in rates of 3-MG transport or GLUT-4 concentrations were observed in the red quadriceps of HI and LI rats. There were no differences found in the rates of 3-MG transport in the white quadriceps of HI, LI, and SED rats although the difference between the HI and SED rats approached significance (P < 0.07). The GLUT-4 concentration and citrate synthase activity of HI rats were significantly greater than SED rats. The 3-MG transport rates of LN rats were twofold greater than SED rats regardless of fiber type, but a difference in GLUT-4 content between the LN and SED rats was observed only in the white quadriceps. GLUT-4 content of the obese rats was significantly correlated with citrate synthase activity (r = 0.93) and 3-MG transport (r = 0.82).(ABSTRACT TRUNCATED AT 250 WORDS)


Sites of infusion and sampling for measurement of rates of production in steady state.

When labeled and unlabeled (endogenously produced) substances enter an organism through different ports of entry, the anatomical location of these entry sites must be taken into account explicitly in calculating rates of appearance. All traditional formulas that are used for calculating rates of appearance are based on the assumption that labeled and unlabeled substances enter by means of the same port. These formulas are, therefore, not in general valid for metabolites such as lactate, where the entry ports differ. In such cases, specific activity will not be uniform throughout the organism even when the labeled and unlabeled substances are both in steady state. One cannot speak of the (unique) specific activity, because none exists. It is useful in these cases to define a distributed specific activity, which is the ratio of the concentration of labeled substance at one anatomical site to the concentration of unlabeled substance at another. We can then show that the rate of appearance for the double steady state (steady tracer infusion method) is given, approximately, as the ratio of the rate of infusion of the labeled substance to a particular distributed specific activity.


Suppression of central noradrenergic neuronal activity inhibits hyperglycemia.

Hypothalamic noradrenergic neuronal activity (NNA) and hepatic glucose output are stimulated by stress. The aim of the present investigation was to examine whether the blockade of noradrenergic responses to stress might suppress the associated hyperglycemia. Mass spectrometry was used for analysis of norepinephrine (NE) and its neuronal metabolite 3,4-dihydroxyphenylglycol (DHPG) in rat hypothalamus, and the ratio DHPG/NE was used as an index of NNA. Treatment of rats with 2-deoxy-D-glucose (500 mg/kg ip, -30 min), yohimbine (10 mg/kg ip, -20 min), or neostigmine (2 micrograms icv, -60 min) increased both NNA and serum glucose (P < 0.05). When rats were additionally pretreated with pentobarbital (60 mg/kg ip; -60 min), the NNA responses were blocked (P < 0.01). At the same time the hyperglycemic responses were also inhibited (P < 0.01). In rats that had reduced NNA due to 7 days "gentling," serum glucose levels were also significantly reduced (P < 0.001) compared with naive controls. The data demonstrate that inhibition of central noradrenergic activity is also associated with an inhibition of hyperglycemia, raising the concept that therapies aimed at reducing central NNA may have a role in the management of diseases with excessive hepatic glucose output such as non-insulin-dependent diabetes mellitus.


Selective expression of an arachidonate 12-lipoxygenase by pancreatic islet beta-cells.

The immunohistochemical distribution of arachidonate lipoxygenases in rat pancreas was characterized with specific polyclonal anti-5-lipoxygenase and anti-12-lipoxygenase antibodies. Immunohistochemical analysis of formaldehyde-fixed paraffin-embedded rat pancreas using anti-12-lipoxygenase antibody and biotin-avidin-peroxidase detection demonstrated specific staining of islets and no staining of pancreatic exocrine tissue. Less intense staining of pancreatic vascular myocytes and endothelial cells was also observed. Immunoblotting of isolated pancreatic islet extracts with the anti-12-lipoxygenase antibody demonstrated immunoperoxidase staining of a single protein band which comigrated with purified 12-lipoxygenase (relative molecular weight = 72,000) on sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. Dispersed cells prepared from isolated islets and then subjected to fluorescence-activated cell sorting and immunostaining exhibited 12-lipoxygenase antigen in beta-cell populations but not in non-beta-cell (predominantly alpha-cell) populations. Assays of enzymatic activity confirmed that the 12-lipoxygenase-catalyzed conversion of arachidonic acid to 12-hydroxyeicosatetraenoic acid methyl ester occurred only with purified beta-cells and not with islet non-beta-cells. No evidence of 5-lipoxygenase antigen or enzymatic activity was found in purified beta-cells or in islet non-beta-cells. We conclude that rat pancreatic islet beta-cells contain an arachidonate 12-lipoxygenase which shares antigenic epitopes with the homologous enzyme contained in tissues from other species. In addition, the selective localization of the 12-lipoxygenase to pancreatic beta-cells and its absence in pancreatic acinar cells and in islet non-beta-cells support observations suggesting that 12-lipoxygenase products may participate in glucose-induced insulin secretion from beta-cells.


Glucose kinetics following administration of an intravenous fat emulsion to low-birth-weight neonates.

To evaluate the mechanism(s) of the observed increase in plasma glucose concentration following the administration of an intravenous fat emulsion to the neonate, we measured glucose kinetics in eight low-birth-weight neonates by the prime constant rate infusion technique with D-[6,6-2H2]glucose at a rate of 0.22 +/- 0.01 mumol.kg-1 x min-1 (39.4 +/- 1.3 micrograms.kg-1 x min-1) while the neonates received 32 +/- 5 mumol.kg-1 x min-1 glucose (6.3 +/- 1.1 mg.kg-1 x min-1) plus an amino acid mixture (parenteral alimentation) alone and in combination with an intravenous fat emulsion (Intralipid). Following the latter combination, there were significant increases in plasma glucose concentration [4.07 +/- 0.11 (73 +/- 2 mg/dl) to 5.00 +/- 0.22 mmol/l (90 +/- 4 mg/dl); P < 0.01] and in plasma insulin concentration [72 +/- 14 (10 +/- 2 microU/ml) to 172 +/- 36 pmol/l (24 +/- 5 microU/ml); P < 0.05]. The parenteral alimentation and intravenous fat effusion combination did not affect the glucose production rate: 0.15 +/- 0.05 mumol.kg-1 x min-1 (0.03 +/- 0.01 mg.kg-1 x min-1) during the parenteral alimentation alone and 0.16 +/- 0.05 mumol.kg-1 x min-1 (0.03 +/- 0.01 mg.kg-1 x min-1) when parenteral alimentation was combined with an intravenous fat emulsion. We conclude that the increased plasma glucose concentration seen in association with administration of parenteral alimentation combined with an intravenous fat emulsion to the premature neonate is not due to enhanced glucose production but could be the result of alterations in glucose utilization.


Thermogenic response to epinephrine in the forearm and abdominal subcutaneous adipose tissue.

Whole body energy expenditure, thermogenic and metabolic changes in the forearm, and intercellular glucose concentrations in subcutaneous adipose tissue on the abdomen determined by microdialysis were measured during epinephrine infusion in healthy subjects. After a control period, epinephrine was infused at rates of 0.2 and 0.4 nmol.kg-1 x min-1. Whole body resting energy expenditure was 4.36 +/- 0.56 (SD) kJ/min. Energy expenditure increased to 5.14 +/- 0.74 and 5.46 +/- 0.79 kJ/min, respectively (P < 0.001), during the epinephrine infusions. Respiratory exchange ratio was 0.80 +/- 0.04 in the resting state and did not change. Local forearm oxygen uptake was 3.9 +/- 1.3 mumol.100 g-1 x min-1 in the basal period. During epinephrine infusion, it increased to 5.8 +/- 2.1 (P < 0.03) and 7.5 +/- 2.3 mumol.100 g-1 x min-1 (P < 0.001). Local forearm glucose uptake was 0.160 +/- 0.105 mumol.100 g-1 x min-1 and increased to 0.586 +/- 0.445 and 0.760 +/- 0.534 mumol.100 g-1 x min-1 (P < 0.025). The intercellular glucose concentration in the subcutaneous adipose tissue on the abdomen was equal to the arterial concentration in the basal period but did not increase as much during infusion of epinephrine, indicating glucose uptake in adipose tissue in this condition. If it is assumed that forearm skeletal muscle is representative for the average skeletal muscle, it can be calculated that on average 40% of the enhanced whole body oxygen uptake induced by infusion of epinephrine is taking place in skeletal muscle. It is proposed that adipose tissue may contribute to epinephrine-induced thermogenesis.


Effects of streptozotocin-induced diabetes on rough endoplasmic reticulum and lysosomes of rat liver.

In the absence of amino acids and insulin, ribosome-free regions of the rough endoplasmic reticulum (RER) invaginate to form an autophagosome, which matures into an autolysosome (W. A. Dunn, Jr., J. Cell Biol. 110: 1923-1933, 1990). In this study, biochemical and morphological methods were used to examine the structure and integrity of the RER and the lysosome-vacuolar system in livers of untreated (normal serum insulin) and streptozotocin (STZ)-treated (depressed serum insulin) fed and fasted rats. Degradation of endogenous proteins was increased by 70% in STZ-treated animals. Proteolysis was further enhanced when these animals were deprived of food for 24 h. These alterations in protein turnover were accompanied by increases in the fractional volume of autophagic vacuoles and in the hepatic amounts of three lysosomal hydrolases. These effects of STZ were prevented on administration of insulin. In addition, there was an insulin-dependent 50% loss of RER surface area in livers from STZ-treated rats. This loss of structural RER was accompanied by comparable decreases in the cellular amounts of two RER membrane proteins and one luminal protein, suggesting that the RER was degraded as a unit. Additional losses of RER were observed when STZ-treated rats were fasted. Furthermore, the hepatic amounts of two serum proteins decreased, suggesting the functional capacity of the RER was reduced. Combined, the data suggest that in STZ-induced diabetes the losses in RER are related to enhanced autophagy.


Pharmacokinetics of ANF and urodilatin during cANF receptor blockade and neutral endopeptidase inhibition.

Urodilatin is a new member of the family of natriuretic peptides. It is of renal origin. Previous reports indicate that urodilatin is natriuretic in lower doses than atrial natriuretic factor (ANF)-(99-126) and that it might be more effective than ANF in the treatment of cardiovascular edema. The present study was designed to compare the pharmacokinetics of the hydrolysis and clearance of 125I-labeled urodilatin and 125I-ANF. In control rats, the volume of distribution (Vss), metabolic clearance rate (MCR), and distribution half-life (distribution t1/2) of urodilatin in plasma were not significantly different from those of ANF. Infusion of clearance (c)ANF-(4-23), a specific ligand for receptors that clear ANF in excess amounts (i.e., a bolus injection of 100 micrograms/kg followed by a continuous infusion of 10 micrograms.kg-1 x min-1), increased the amount of intact peptide in the plasma to the same extent for both urodilatin and ANF. In addition, cANF-(4-23) decreased the Vss and the MCR and increased the distribution t1/2 of both peptides to about the same degree. Prior treatment of rats with SQ-28,603, a specific neutral endopeptidase (NEP; EN 3.4.24.11) inhibitor, was without significant effect on the metabolic clearance of urodilatin, whereas it decreased the clearance of ANF by 65%. Furthermore, an infusion of SQ-28,603 suppressed the appearance of the hydrolytic products of ANF in blood but not of urodilatin. Moreover, the inhibitor increased the total amount of ANF recovered in the kidneys to five times the control values, whereas it did not alter the renal uptake of urodilatin.(ABSTRACT TRUNCATED AT 250 WORDS)


Reciprocal feedback regulation of kidney angiotensinogen and renin mRNA expressions by angiotensin II.

The present study asks whether angiotensin II (ANG II), a potent inhibitor of renal renin synthesis and release, regulates renal angiotensinogen synthesis. ANG II (or vehicle) was intravenously infused into male Sprague-Dawley rats for 3 days (vehicle or 100, 300, and 1,000 ng.kg-1 x min-1, n = 8/group), significantly increasing mean plasma ANG II concentrations and raising mean arterial blood pressure (MAP). ANG II dose dependently suppressed plasma renin concentration, kidney renin concentration, and renal renin mRNA levels. In contrast, ANG II infusion increased renal angiotensinogen mRNA levels stepwise to 122, 136 (P < 0.05), and 150% (P < 0.05) of control and also increased both liver mRNA levels (P < 0.05) and plasma angiotensinogen concentration (P < 0.05). Three days of angiotensin-converting enzyme inhibition (10 mg.kg-1 x day-1 quinapril in drinking water, n = 8) significantly decreased MAP (P < 0.05) and increased both mean plasma renin concentration (P < 0.05) and renal renin mRNA levels (P < 0.005). Plasma ANG II concentration tended to decrease (not significant), and neither renal nor hepatic angiotensinogen mRNA levels displayed significant difference. However, when data from ANG II-infused and quinapril-treated rats were analyzed together, correlation between plasma ANG II concentrations and renal angiotensinogen mRNA levels was highly significant (P < 0.005, r = 0.585). Thus plasma ANG II upregulates renal angiotensinogen gene expression and downregulates renal renin gene expression, a reciprocal feedback regulation that may have important physiological consequences.


Fasting and postmeal phenylalanine metabolism in mild type 2 diabetes.

We have investigated postabsorptive and postprandial phenylalanine kinetics in non-obese type 2 diabetic patients [non-insulin-dependent diabetes mellitus (NIDDM)], using a double-isotope technique and the constant oral administration of a synthetic mixed meal. Fasting and postmeal glucose levels were increased (P < 0.01) in NIDDM (165 +/- 16 to 226 +/- 24 mg/dl), with respect to normal controls (85 +/- 3 to 102 +/- 6 mg/dl). Fasting insulin concentrations were comparable in NIDDM (13 +/- 2 microU/ml) and in normals (12 +/- 2 microU/ml), but after the meal it increased less (P < 0.07) in NIDDM vs. normals (to 36 +/- 5 vs. 56 +/- 12 microU/ml, respectively; P < 0.01 vs. basal for both). Postabsorptive phenylalanine rate of appearance (R(a)) in NIDDM (0.63 +/- 0.08 mumol.kg-1 x min-1) was comparable to that of controls (0.73 +/- 0.05 mumol.kg-1 x min-1, not significant). During the meal, total and endogenous phenylalanine R(a), splanchnic uptake, oxidation, and nonoxidative disposal of the ingested phenylalanine were also comparable in the two groups. These data indicate that fasting and postprandial kinetics of the essential amino acid phenylalanine are normal in NIDDM.


Adrenergic regulation of type II 5'-deiodinase circadian rhythm in rat harderian gland.

This paper reports on the regulation of the nyctohemeral profile of type II thyroxine 5'-deiodinase (T45'D) activity in the rat harderian gland. Harderian gland T45'D activity exhibits a nighttime increase with maximal values late in the dark period (0200-0400 h) and basal values during the daytime. The nocturnal rise of the deiodinating activity was prevented by either exposure of animals to light at night, injecting the animals with both alpha- and beta-adrenergic receptor blockers, or bilateral superior cervical ganglionectomy (SCGx). However, adrenalectomy did not affet the enzyme activity in the harderian gland. In brown adipose tissue (BAT), where thyroid hormone metabolism is extremely dependent on alpha 1-adrenergic stimulation by blood-circulating catecholamines, adrenalectomy significantly decreased T45'D activity. Deiodinating activities in brain frontal cortex (BFC) and pituitary gland were unaffected by adrenalectomy. Unlike in the harderian gland, SCGx did not modify the T45'D activity in either BAT, BFC, or the pituitary gland. The results suggest that elevated plasma catecholamines are not required for harderian gland T45'D activation and that the nyctohemeral profile of the enzyme activity in the harderian gland is dependent on the noradrenergic input from the superior cervical ganglia.


Glucose-induced insulin release in islets of young rats: time-dependent potentiation and effects of 2-bromostearate.

The development of glucose-stimulated insulin release and time-dependent potentiation (TDP) has been studied in isolated islets from 7-, 14-, and 21-day-old and 3-mo-old rats. Responses were small at 7 days and changed little at 14 days. At 21 days the amount of insulin released in response to glucose was two times that at 14 days but was still less than one-half that released by 3-mo islets. Glucose-induced TDP was absent at 7 days but was present at 21 days. The second phase response to glucose decreased with perifusion time in 7-, 14-, and 21-day islets. In 7- and 21-day islets, high glucose in the presence of 2-bromostearate, an inhibitor of fatty acid oxidation, prevented the time-dependent decrease in responses; in addition, it induced TDP and enhanced TDP in the 7-day and 21-day islets, respectively. The data suggest that, in the young islet, glucose metabolism fails to inhibit fatty acid oxidation as it does in the mature islet and that this leads to a diminished signal for stimulus-secretion coupling.


Inhibition of hepatic ketogenesis by tumor necrosis factor-alpha in rats.

Tumor necrosis factor-alpha (TNF-alpha) stimulates hepatic lipogenesis. Therefore, it could play a role in the control of ketogenesis. To test this hypothesis, we measured simultaneously free fatty acids (FFA; [1-13C]palmitate) and ketone body (KB; [3,4-13C2]acetoacetate) kinetics, before and after intraperitoneal injection of saline or TNF-alpha, in postabsorptive rats or rats starved for 24 h. In both groups of rats, TNF-alpha injection did not modify insulinemia and induced a moderate increase of FFA concentrations and appearance rates (P < 0.05). Despite increased FFA availability, ketogenesis was impaired after TNF-alpha injection, as shown by lower KB concentrations and appearance rates; this effect was more important in postabsorptive than in starved rats. The percentage of FFA flux used for ketogenesis was decreased by TNF-alpha in the postabsorptive group (P < 0.05) and starved (P < 0.05) rats. In both groups, maximal liver acetyl-coenzyme A carboxylase activity and estimated phosphorylation state were not modified by TNF-alpha injection, but hepatic concentrations of citrate were increased (P < 0.05). This increased citrate level could be related to a mobilization of glucose stored as glycogen since liver glycogen was decreased by TNF-alpha injection (P < 0.05). In conclusion, TNF-alpha injection in rats decreased hepatic ketogenesis. This action could be related to an increased mobilization and utilization of carbohydrate stores.


Visceral fat accumulation in obese subjects: relation to energy expenditure and response to weight loss.

Seventy-eight healthy obese subjects, 40 premenopausal women and 38 men aged 27-51 yr received a 4.2 MJ/day energy-deficit diet for 13 wk. Resting metabolic rate (RMR) and diet-induced thermogenesis (DIT) were measured by indirect calorimetry. Abdominal subcutaneous and visceral fat areas were calculated from magnetic resonance imaging scans before and after weight loss. Before weight loss, visceral fat accumulation was positively correlated with higher levels of RMR (P < 0.05) and DIT (P < 0.01) in women but not in men. The mean weight reduction was 12.2 +/- 3.5 (SD) kg. In men but not in women, an initially large visceral fat depot was associated with a reduced loss of weight and total fat mass (P < 0.05). Within each sex, an initial abundance of visceral fat was significantly related to a larger loss of visceral fat (P < 0.001) and in men to a smaller loss of subcutaneous fat (P < 0.05). These results suggest that there may be gender differences in the associations between visceral fat accumulation and components of energy expenditure (RMR and DIT) in obese subjects. Obese subjects with an initial abundance of visceral fat do not lose more body weight but more visceral fat than subjects with less visceral fat.


Early metabolic consequences of epidermal growth factor administration to neonatal rats.

Daily administration of epidermal growth factor (EGF) to neonatal rodents elicits a classic morphogenetic syndrome. In this study, we examined the early (minutes to hours) consequences of EGF treatment in the neonatal rat (age 0-72 h). Significant findings included a rapid reduction in resting heart rate 4 h after EGF treatment accompanied by a sensitive dose- and age-dependent decrease in systemic oxygen consumption (VO2). Midscapular skin temperature (MST) was measured as a putative noninvasive indicator of brown adipose tissue thermogenesis. As little as 10 ng EGF/g body wt elicited a significant reduction in MST. Both the decrease in VO2 evoked by EGF and the MST response were potentiated by environmental cold exposure. EGF treatment also resulted in rapid (90 min) reductions in circulating levels of glycerol, triglyceride, and cholesterol while increasing serum glucose and arachidonic acid. Other free fatty acids were unaffected. Serum lactate levels were increased by EGF with the same time course as the reduction in VO2. These results provide new biochemical data on the pharmacological actions of EGF and further characterize the EGF-treated neonatal rodent as an intriguing in vivo model of growth factor action.


Leucine as a regulator of whole body and skeletal muscle protein metabolism in humans.

Leucine has been proposed as an in vivo regulator of protein metabolism, although the evidence for this in humans remains inconclusive. To test this hypothesis, we infused either L-leucine (154 +/- 1 mumol.kg-1 x h-1) or saline intravenously in six healthy men in two separate studies. L-Leucine infusion increased plasma concentrations of leucine and alpha-ketoisocaproate from 112 +/- 6 and 38 +/- 3 mumol/l to 480 +/- 27 (P < 0.001) and 94 +/- 13 mumol/l (P < 0.001), respectively, without any significant change in circulating insulin or C peptide levels. Leucine infusion decreased plasma concentrations of several amino acids and decreased whole body valine flux and valine oxidation (using L-[1-13C]valine as a tracer) and phenylalanine flux (using [2H5]-phenylalanine as a tracer). According to arteriovenous differences across the leg, the net balance of phenylalanine, valine, and lysine shifted toward greater retention during leucine infusion, whereas alanine balance did not change. Valine release and phenylalanine release from the leg (estimated from the dilution of respective tracers) decreased, indicating inhibition of protein degradation by leucine infusion. We conclude that leucine decreases protein degradation in humans and that this decreased protein degradation during leucine infusion contributes to the decrease in plasma essential amino acids. This study suggests a potential role for leucine as a regulator of protein metabolism in humans.


Hypertension and insulin resistance: role of sympathetic nervous system activity.

The purpose of this study was to test the hypothesis that heightened sympathetic nervous system (SNS) activity contributes to the mechanism by which hypertension is associated with insulin resistance in humans. We performed frequently sampled intravenous glucose tolerance tests to determine tissue sensitivity to metabolic effects of insulin (SI) and measured plasma norepinephrine (NE) levels in 21 normotensive and 14 hypertensive Caucasian subjects. Compared with the normotensive subjects, hypertensive subjects had decreased SI (5.4 +/- 0.5 vs. 4.0 +/- 0.7 x 10(-5) x min-1 x pM-1; P = 0.03) but similar plasma NE levels (normotensive: 1.82 +/- 0.12 vs. hypertensive: 1.73 +/- 0.16 nM; P = 0.23). In a multiple regression model, only body mass index (BMI) and mean arterial blood pressure (MABP) were significant independent predictors of SI [SI = (-0.513)(BMI) + (-0.058)(MABP) + 23.6; r = 0.748; P = 0.0001]; age, plasma glucose, epinephrine, and NE level did not enter this model. As an additional test of this hypothesis, seven hypertensive subjects were restudied after 10 days of guanadrel therapy to determine whether SI would increase during suppression of SNS activity by guanadrel. Despite a significant reduction in plasma NE levels with guanadrel (baseline: 1.63 +/- 0.18 vs. guanadrel: 0.99 +/- 0.14 nM; P = 0.01), there was no significant change in SI (baseline: 2.97 +/- 0.78 vs. guanadrel: 2.41 +/- 0.54 x 10(-5).min-1 x pM-1; analysis of variance P = 0.57). We conclude that, in the Caucasian population we studied, heightened SNS activity is not essential for the insulin resistance observed in hypertensive humans.