Acute ventilation-perfusion mismatching resulting from inhalative smoking of the first cigarette in the morning.

The effect of the first cigarette in the morning on the airway resistance (Raw) which can be measured by body-plethysmography was investigated in 70 inhaling cigarette smokers. The test population showed a significant (P less than 0.0005) fall in Raw 8 min after smoking. A further study (n = 16) showed that the fall in Raw was most likely to be attributable to a decrease in the trapped air. The effect of the first cigarette in the morning on the arterial blood gases and on the alveolar-arterial oxygen difference P(A-a)O2 and carbon dioxide difference P(A-a)CO2 was investigated in 12 inhaling cigarette smokers. Smoking gave rise to a significant (P less than 0.0005) fall in the partial pressure of oxygen (PaO2) with compensatory overventilation. At the same time, the P(A-a)O2 and the P(A-a)CO2 increased significantly (P less than 0.01 and P less than 0.05, respectively). This effect could be observed for up to 24 min after smoking. In addition, the flow of blood in the pulmonary capillaries was measured in 28 test subjects with the nitrous oxide method (QN2O) before, and 18-22 min after, smoking the first cigarette in the morning. After smoking, there was a significant (P less than 0.0005) fall in the QN2O by an average of 11.3%. The decrease in the Raw, the fall in the PaO2 with compensatory overventilation, the increase in P(A-a)O2 and P(A-a)CO2 and the decrease in the QN2O are interpreted as manifestations of pronounced acute ventilation-perfusion mismatching induced by smoking.


Smoking behaviour and increase in nicotine and carboxyhaemoglobin in venous blood.

The connection between smoking behaviour (number of puffs, puff volume, depth of inhalation, duration of inhalation) and the increase in both nicotine and carboxyhaemoglobin (COHb) in venous blood was investigated with methods developed especially for measurement of the puff volume, the depth of inhalation, and the duration of inhalation in 28 inhaling cigarette smokers. A significant correlation could be demonstrated between the smoking parameters and the nicotine and carboxyhaemoglobin increase. The weighting obtained shows that the number of puffs is the most important parameter affecting the increase in nicotine, whereas the depth of inhalation and the puff volume are of much less relevance. The duration of inhalation does not affect the nicotine level. A significant increase in nicotine cannot be attained in non-inhalative smoking of cigarettes with an acid mainstream smoke (n = 14). The increase in COHb is most affected by the puff volume, and slightly less by the number of puffs and the depth of inhalation. The duration of inhalation does not affect the COHb level.


Uptake of tobacco smoke constituents on exposure to environmental tobacco smoke (ETS).

For the purpose of risk evaluation, passive smoking is frequently regarded as low-dose cigarette smoking. However, since the physical, chemical and biological properties of mainstream smoke (MS), which is inhaled by the smoker and environmental tobacco smoke (ETS), which is breathed by the passive smoker are quite different, risk extrapolation from active smoking to passive smoking is of doubtful value. In a series of experimental exposure studies we compared the uptake of tobacco smoke constituents by active and passive smoking. The results show that biomarkers which were found to be elevated after experimental ETS exposure, such as nicotine and cotinine in plasma and urine as well as thioethers in urine, indicate gas-phase exposure in passive smokers, but particle-phase exposure in active smokers. Biomarkers which should indicate the uptake of particle-bound, genotoxic substances with ETS, such as urinary mutagenicity, metabolites of polycyclic aromatic hydrocarbons (PAH) and DNA adducts, were not found to be elevated even after extremely high ETS exposure. From these results we conclude that a risk evaluation for passive smoking on the basis of dosimetric data is currently not possible.


Long-term effects of cancer on children and their families.

An increasing number of children now survive malignancies, which has implications for nursing practice in caring for long-term survivors and their families. This article will examine the physical, psychological and social consequences of surviving childhood cancer and will suggest how nurses can meet the needs of long-term survivors.


The contributions of cigarette yield, consumption, inhalation and puffing behaviour to the prediction of smoke exposure.

The overall predictability of smoke exposure indicators and the importance of different influencing factors were assessed in a cross-sectional study (n = 144), using multiple linear regression and bivariate correlation analyses. Respiratory CO, and plasma nicotine and cotinine concentrations were measured before and after smoking, for lip or holder smoking, and natural or standardized (30 puffs) puffing. The prediction of smoke exposure measures varied considerably across sampling times, smoking conditions, and dependent variables. The variance of plasma cotinine and nicotine were predictable to a considerable extent (30%; 19-41%) by cigarette yield, consumption and self-reported inhalation, whereas respiratory CO was less predictable (15-27%). Generally, consumption was the most important predictor, surpassed by nicotine yield for post-smoking plasma nicotine. Smoke exposure from a single smoking period could be predicted to a variable degree (CO, 11-42%; nicotine, 33-54%) by a subset of smoker's sex, cigarette yield, self-reported inhalation and puffing characteristics. The highest prediction was found under standardized smoking conditions (30 puffs through a holder), the lowest under natural smoking conditions. The best subset of predictors, especially with respect to puffing parameters, was found to vary considerably across smoking conditions and dependent variables.


Using a monitored dosage system.

Traditional methods of administering medicines in nursing and residential homes have varied in standard throughout the UK. Monitored dosage systems have the potential to remedy this by making drug administration easier, safer, more hygienic and quicker. This article describes the use of one such system.


Management of lymphoedema: a community-based approach.

Lymphoedema causes considerable physical, emotional and social problems. This article describes the establishment of a community lymphoedema service in one district health authority. The proposal won the Queen's Nursing Institute Innovation Award in 1991. A second article will review the first year of the clinical service.


Safety from sharps.

Needlestick and sharps injuries are responsible for 35% of hospital injuries to staff. Despite this, there has been little effort in the past to reduce potential hazards. Nurses and other healthcare personnel must be made aware of the risks so that they can improve their practice.


Changes in the amphibian antibody repertoire are correlated with metamorphosis and not with age or size.

Tadpole and adult Xenopus, manipulated to be of comparable size, exhibited stage-specific antibody expression. The production of adult-type higher-affinity anti-DNP antibodies proved to be independent of the age and size of the individual and is concomitant with the completion of metamorphosis. The appearance of new antibody specificities at such a time suggests that their expression occurs with the cell turnover and renewal during a period of morphological changes.


Developmental regulation of sialoadhesin (sheep erythrocyte receptor), a macrophage-cell interaction molecule expressed in lymphohemopoietic tissues.

Stromal macrophages in lymphohemopoietic tissues express novel macrophage-restricted plasma membrane receptors involved in nonphagocytic interactions with other hemopoietic cells. One such receptor with lectinlike specificity for sialylated glycoconjugates on sheep erythrocytes and murine hemopoietic cells has been characterized immunochemically and termed sialoadhesin. We have examined sialoadhesin expression during mouse development to learn more about its regulation and function. Immunocytochemical, rosetting, and Western blot studies show that sialoadhesin is first detected on fetal liver macrophages on day 18 of development, 7 days after numerous F4/80+ macrophages are found within erythroblastic islands. In spleen and bone marrow, sialoadhesin appears between day 18 and birth, in parallel with myeloid development. Strongly labeled macrophages in the marginal zone of spleen, characteristic of adult lymphoid tissues, appeared gradually between 1-4 weeks after birth, as the white pulp became enlarged. Isolation of fetal liver macrophages at day 14 confirmed that sialoadhesin was not involved in the binding of erythroblasts, which is mediated by a distinct cation-dependent receptor (Morris et al., 1988, p. 649). Sialoadhesin could be expressed by isolated fetal liver macrophages after cultivation in adult mouse serum, a known source of inducer activity, but was not dependent on the presence of this inducer, unlike adult-derived macrophages. Fetal plasma contained inducing activity on day 13, but adult levels were not reached until 2 weeks postnatally. These studies show that sialoadhesin is differentially regulated compared with the erythroblast receptor and F4/80 antigen, that it is not required for fetal erythropoiesis, and that its induction on stromal macrophages is delayed until the onset of myeloid and lymphoid development. Sialoadhesin provides a marker to study maturation and functions of macrophages during ontogeny of the lymphohemopoietic system.


How to choose the right applicant: 2.

Deciding which candidate to appoint requires considerable discussion and skill. Giving feedback to the unsuccessful candidate should be carefully considered.


Interpersonal skills training in Brunei.

This article describes an interpersonal skills training workshop set up in Brunei, Darussalam. It identifies important issues in the facilitation of such workshops, which have relevance for interpersonal skills training in a range of cultures.


Nurse information systems: how to gain competitive advantage.

This article considers how nurse information systems can make provider units more competitive by supporting a quality-based strategy, and examines the organizational characteristics necessary for success.


A child's right to die: who should decide?

When deciding whether to treat children, quality of life is as important as quantity of life. There is some confusion over who has the right to make these treatment decisions. Healthcare professionals are often not the most appropriate decision-makers.


Unrelated donor marrow transplants for severe acquired aplastic anemia.

This report is divided into two parts. The first part is a retrospective analysis of 40 unrelated transplants [UD-BMT] for severe acquired aplastic anemia [SAA], performed at five transplant centers between 1981 and 1990. The second is an interim analysis of 15 UD-BMT for SAA compared with a matched cohort of 16 sibling transplants [ID-BMT] carried out since February 1989 using prospectively collected data provided by the IMUST Study Group. In the retrospective study the actuarial survival was 28% [+/- 15] with a median follow-up of 1485 [266-3890] days post BMT. Univariate analysis showed a considerable survival advantage for patients younger than 15 years at BMT [p = 0.03]. More recently patients entered in the IMUST Study showed an actuarial survival of 50% [+/- 27] for UD-BMT compared with 58% [+/- 31] for ID-BMT recipients. These data suggest that UD-BMT is a realistic option for paediatric patients with SAA. Although numbers are very small there is some indication from IMUST Study data that better patient selection and intensive BMT protocols may also improve the results of UD-BMT in young adult patients with SAA.


Cord blood transplants: potential utility and potential limitations.

Cord blood has been utilized successfully for the hematopoietic reconstitution of children with lethal disorders of hematopoiesis, as an alternative to marrow derived stem cells. The majority of the transplants performed to date have utilized umbilical cord blood from HLA-identical siblings, however, much of the interest in this modality is due to its potential as a source of readily available unrelated stem cells. Cord blood offers intriguing theoretical advantages over the use of unrelated bone marrow, but additionally suffers from several limitations as well. This review is intended to highlight a number of these issues, rather than to serve as a detailed review of the clinical experience with cord blood transplantation to date.


Cancer after bone marrow transplantation. IBMTR and EBMT/EULEP Study Group on Late Effects.

Cancer may be serious late effect of marrow transplantation. Radiation, chemotherapy, immunosuppression and the original disease for which transplantation was performed may predispose to the development of cancer. 116 of 9732 patients reported to the IBMTR (International Bone Marrow Transplant Registry) have developed a new malignancy. Late effects were evaluated by the EBMT-EULEP (European Bone Marrow Transplant-European Late Effect Project) Late Effect Study Group in 147 patients surviving 6 years and 79 patients surviving more than 10 years. New malignancies developed in 11 of these patients. Lymphomas and leukemia comprised 73 cases reported to the IBMTR and one case reported to the EBMT-EULEP study. Tumors of the skin, oropharynx, vulva vagina and cervix prevailed in 41 patients with solid tumors. The distribution of malignancies is similar to that observed in organ transplant patients not given radiation or chemotherapy and suggests immunosuppression as a major contributory factor. In dogs the incidence of malignancies was studied after either chemotherapy or total body radiation in various regimens and marrow transplantation. Both chemotherapy and radiation shortened tumor-free survival in comparison to untreated dogs. Higher doses, larger fractions and shorter treatment schedules enhanced earlier tumor development. Soft tissue sarcomas and thyroid carcinoma were most frequent in treated, mammary carcinoma in untreated dogs. In treated dogs deaths from cancer were observed starting at the age of 5 years as compared to untreated dogs at the age of 9 years. The data from animal experiments indicate that the incidence of solid tumors in marrow transplant patients may still rise in the coming decades.


Transplants in AML.

Three therapies are widely-used to treat acute myelogenous leukemia (AML): allogenic bone marrow transplants, autotransplants and chemotherapy. Which of these therapies is best is controversial. Analyzing and comparing results of these therapies is complex and controversial. Comparisons of published data are flawed by biased reporting and subject selection. Randomized trials are also reported but are limited by small numbers of subjects and the question of whether their conclusions apply to most persons with AML. Hypotheses being tested in randomized trials are often misunderstood or relevant to only a subset of persons with AML. Furthermore, in many trials a substantial proportion of subjects do not receive the intended treatment. Observational data bases are also used to compare results of different AML therapies. Although this is probably the most effective analytic approach, substantial differences in outcome-related variable between treatment groups make complex statistical adjustment necessary. Validity of these adjustments is controversial. Limitations of these diverse approaches to comparing results of different therapies of AML suggests that a precise answer to the question of how best to treat AML is unlikely to be forthcoming. This uncertainty is further confounded by the considerable subjectivity that influences how physicians choose between alternative therapies. The net result of these considerations is a consensus approach to treating AML is unlikely to develop, probably because results of diverse treatments are not very different.


T cell tolerance after bone marrow transplantation in mice.

This article provides a brief overview of T cell tolerance induction in the thymus, using parent----F1 bone marrow (BM) chimeras as a model. Although intrathymic tolerance is controlled largely by BM-derived cells, experiments with BM chimeras suggest that thymic epithelial cells can make a major contribution to tolerance induction, especially for high-affinity T cells. Whether extrathymic mechanisms contribute to tolerance induction remains controversial: evidence against this possibility is provided by the finding that transferring normal parental strain T cells to parent----F1 chimeras leads to immunogenicity rather than tolerogenicity. Breakdown of self tolerance is discussed in terms of the phenomenon of "auto-GVHD".


Is there a better way to deliver total body irradiation?

The available data suggest that the antileukemic, immunosuppressive and toxic effects of TBI are highly dose dependent and if TBI is given as single daily fractions at 5-10 cGy/minute, an optimal dose for the treatment of most leukemias is somewhere between 12 and 16 Gy. Giving radiation as a single dose rather than fractionating it increases both its immunosuppressive as well as its toxic effects. The relative anti-leukemic effects of single vs. fractionated irradiation are less clear, but available data support the view that fractionation does not substantially reduce the effects of TBI on myeloid tissue. Increasing the dose rate increases toxicities and, although data are not yet complete, likely increases both immunosuppressive and anti-tumor effects. The impact of total dose, dose fractionation and dose rate are highly interdependent and how best to manipulate these 3 factors to lead to an optimal combination is as yet unknown. Directing radiotherapy to sites of leukemia using monoclonal antibodies or other carriers such as growth factors is feasible and, although there are many aspects of this approach which have yet to be worked out, targeted radiotherapy may prove to be the best way to achieve the therapeutic goals of increased tumor ablation and immunosuppression without increased toxicities.


Who should get a second marrow transplant?

Second transplants need to be considered in two clinical situations after marrow transplantation. Firstly, failure of sustained engraftment; secondly, recurrence of the underlying malignancy. In patients with failure of sustained engraftment a trial of recombinant human GM-CSF is indicated first with a chance of improving blood counts in a significant proportion of patients. If this is unsuccessful a second transplant utilizing a preparative regime aimed primarily at further minimizing host immune competence such as a combination of antithymocyte globulin (ATG) and cyclophosphamide or ATG alone followed by a T-replete marrow infusion should be employed. A second marrow transplant can also be utilized for recurrence of the underlying haematological malignancy after first transplant. However, several large multi-institutional studies have now shown a striking difference in the long-term leukemia-free survival rate between those relapsing early (for example, less than six months) after the first transplant compared to those relapsing later after the first transplant. Leukemia-free survival post second transplant for those relapsing within six months of first transplant is less than 10%, whereas for those relapsing greater than six months from first transplant it is approximately 30%. Transplant-related mortality, particularly from complications influenced by chemotherapy, such as interstitial pneumonitis and hepatic veno-occlusive disease, are more common after second than after first transplant.(ABSTRACT TRUNCATED AT 250 WORDS)


Wolman's disease: a review of treatment with bone marrow transplantation and considerations for the future.

Wolman's disease is a fatal disorder characterized by absence of acid lipase and accumulation of cholesterol esters. Inanition due to malabsorption and intractable diarrhea has been the most prominent cause of early demise within the first year. Further complications have included cirrhosis and pulmonary failure due to cholesterol ester storage in respective cells. Although sustained caloric balance can be maintained by total parenteral nutrition, this has not altered the eventual course of disease. The acid lipase deficiency in leucocytes in Wolman's disease can be corrected subsequent to bone marrow transplantation. This has proven to be the case in two patients so transplanted. In two other patients, engraftment was not obtained following bone marrow transplantation. The concept of treatment of Wolman's disease by providing normalization of the acid lipase activity by allogeneic bone marrow transplantation remains valid. However, improvement of bone marrow transplant procedure needs to be implemented since pre-existing morbid pathology enhances toxicity and may prevent engraftment. Alternative modifications for accomplishing sustained engraftment without toxicity need to be examined. Other potential therapies need to be inspected in treatment of patients with Wolman's disease. The capability of reducing cellular cholesterol synthesis by use of lovastatin, an inhibitor of 3-hydroxy-3-methylglutaryl-CoA reductase, is now available. In the future, isolation and purification of acid lipase will allow for direct infusion of missing enzyme. The molecular biology now known concerning acid lipase gene holds promise for the future for recombinant manufacturing of acid lipase. And, gene therapy with its use of autologous bone marrow transplantation will be tried in future.(ABSTRACT TRUNCATED AT 250 WORDS)


Absence from school and mental health.

Severe school attendance problems, which once commanded a great deal of attention in child and adolescent psychiatry, have fallen from favour and are increasingly viewed as varieties of social impairment which may accompany disorders such as anxiety disturbances in the case of school refusal and conduct disturbances in the case of truancy. It is argued that this relegation of school attendance difficulties may have gone too far. As presenting complaints, albeit sometimes masked by apparent physical illness, they still have much to recommend them as indicators of a wide variety of present and future problems: educational, social, family, legal, medical, and, last but not least, psychiatric. Prevalence, features, causative factors, outcome, and management are discussed. Particular attention is paid to DSM and ICD classification. Gaps in present knowledge are indicated.


Anna O. had a severe depressive illness.

The information available on the illness of Anna O. is reviewed together with follow-up data from the literature. It is concluded that the diagnosis of a severe depressive illness with depressive delusions is well justified. Hysterical symptoms which appeared can be understood as part of the depressive state modified by the expectations of the period and by the intervention of physicians. The illness was a very protracted one, with fluctuations or exacerbations lasting from 1880 to 1887, and was complicated by dependence upon morphine and chloral hydrate. However, by 1888, the patient appears to have made a considerable recovery, and she went on to lead an effective and fruitful life, demonstrating high intelligence and the resilience of the cyclothymic temperament.


A comparison of academic and lay theories of schizophrenia.

This study investigated lay subjects' theories of schizophrenia. A questionnaire examining the five identified main academic theories of schizophrenia (medical, moral-behavioural, social, psychoanalytic, and conspiratorial) along various dimensions (aetiology, behaviour, treatment, function of the hospital, and the rights and duties of both patients and society) was constructed for use in the study. The results from 106 lay respondents showed that no single model was favoured exclusively but seemed to point to a synthesis of several academic theories. The lay subjects stressed the importance of patient environment in the aetiology of schizophrenia rather than a physiological malfunction, but tended to stress the personal rights of the schizophrenic. The differences between lay and the currently dominant psychiatric models are discussed in terms of the function these models serve for each group.


Women whose mental illnesses recur after childbirth and partners' levels of expressed emotion during late pregnancy.

Expressed emotion (EE) in the partners of 25 pregnant women with a history of psychosis or severe depression and in 13 pregnant control subjects without any previous psychiatric disorder was assessed in the ninth month of pregnancy. At this time, no patient presented as a case according to RDC. Eleven subjects with a history of psychiatric disorder experienced a further episode of illness in the six months following delivery. Partners of women who became ill had made fewer critical and positive comments about their wives during the pregnancy than the partners of women who remained well. Poor self-rated social adjustment in the partners was also predictive of recurrence of illness after delivery.


The influence of family expressed emotion on the course of schizophrenia in a sample of Spanish patients. A two-year follow-up study.

A sample of 60 Spanish schizophrenic patients was studied to ascertain the relationship between their relatives' expressed emotion (EE) and relapse at follow-up. The relatives' EE and patients' relapse were operationalised following Leff & Vaughn's criteria. At nine months a significant association was not found between the relatives' EE and relapse, but this association became significant on reclassifying the relatives' EE scores after decreasing to four points the cut-off point for critical comments. At 24 months no association was found between EE and relapse. There was a tendency for patients who interrupted their medication or who did not work to relapse more frequently, particularly among the high-EE group.


Alzheimer's disease, other dementias, depression and pseudodementia: prevalence, incidence and three-year outcome in Liverpool.

A group of 1070 community-living persons aged 65 and over was assessed using the GMS-AGECAT package and other interviews at years 0 and 3. Year 3 interviewers were 'blind' to the findings at year 0, and the prevalence of organic disorders and depression was very similar in both years. According to the results at year 3, minimum and maximum prevalence figures for dementia at year 0 were 2.4% and 3.8% for moderate to severe and 0.4% and 2.4% for mild or early cases, with a best estimate of 3.5% and 0.8%, or 4.3% overall, divided into: senile, Alzheimer's type 3.3%; vascular 0.7%; and alcohol-related 0.3%. The overall incidence of dementia, clinically confirmed by six-year follow-up, was 9.2/1000 per year (Alzheimer type 6.3, vascular 1.9, alcohol related 1.0). Three years later, 72.0% of those with depressive psychosis and 62.3% of those with depressive neurosis were either dead or had some kind of psychiatric illness. Nearly 60% of milder depressive cases (7.2% of the total sample) had either died or developed a chronic mental illness. The outcome of depressive pseudodementias is equivocal so far. Findings at year 3 provide validation of AGECAT computer diagnosis against outcome; organic and depression diagnoses are seen to have important implications for prognosis.


Alexithymia in women with anorexia nervosa. A preliminary investigation.

The prevalence of alexithymia in 48 female anorexia nervosa patients was 77.1% compared with a prevalence of 6.7% in 30 normal female subjects, matched by age and education. Alexithymia correlated negatively with education in the anorexic patient group, but was unrelated to duration of illness, amount of weight loss, and levels of depression and of general psychoneurotic pathology.


Neurosyphilis and schizophrenia.

Neurosyphilis continues to present in atypical forms, leading to erroneous diagnoses by physicians and psychiatrists. This patient, with a previous history of psychosis, presented in a catatonic state with rhabdomyolysis and renal failure. A subsequent breakdown was thought to be schizophrenic until unusual features led to a reassessment and discovery of neurosyphilis which was treated with penicillin and resulted in a remarkable clinical recovery.


Neuroleptic malignant syndrome presenting as hyperosmolar non-ketotic diabetic coma.

A 50-year-old man presented with hyperosmolar non-ketotic diabetic coma associated with the neuroleptic malignant syndrome (NMS) after intramuscular treatment with haloperidol. It is suggested that NMS may occur as a complication of uncontrolled diabetes mellitus with dehydration. Conversely, NMS might precipitate diabetic coma in patients with previously well controlled blood glucose.


Life-threatening allergic reaction to clozapine.

Clozapine, an 'atypical' antipsychotic drug, rarely induces allergic complications, which usually present as cutaneous reactions. We report the case of a 69-year-old woman, suffering from chronic schizophrenia, who developed an allergic asthmatic reaction following clozapine therapy. Intensive-care treatment was necessary. The reaction could be repeated by further exposure to the drug. Skin tests for hypersensitivity were negative.


Successful treatment of episodic dyscontrol with carbamazepine.

Following a road-traffic accident, an 18-year-old man developed episodic dyscontrol which brought him into conflict with the law. Two years after the accident, treatment with carbamazepine was initiated and further aggressive outbursts subsided. The efficacy and mode of action of carbamazepine is discussed and the literature reviewed.


Visual hallucinations as the presenting symptom of senile dementia.

A case of senile dementia that initially presented with complex visual hallucinations in the absence of clinical cognitive impairment or other psychopathology is described. Dementia must be added to the differential diagnosis of isolated visual hallucinations in the elderly.


Self-neglect in adult life.

Two cases of self-neglect in adult patients with no psychiatric diagnosis are reported. The presentation included domestic squalor and hoarding of rubbish, with the patients living alone and having a history of schizoid and paranoid personality traits. Both refused all recommended help. A move to more protected accommodation was the only practical measure that led to a degree of improvement.


Increases in extracellular dopamine levels and locomotor activity after direct infusion of phencyclidine into the nucleus accumbens.

Three studies were conducted to provide a further characterization of the neurochemical and behavioral effects of phencyclidine (PCP). The first experiment utilized in vivo microdialysis to measure extracellular levels of dopamine (DA), dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the nucleus accumbens. Administration of PCP (4.0 x 10(-4) M) in the dialysis perfusion medium produced large increases in extracellular DA, and biphasic changes in DOPAC. In the second experiment, chronic indwelling cannulae for drug infusion were implanted bilaterally into the nucleus accumbens. Local infusions of PCP (15.0, 30.0 or 60.0 micrograms per side) produced substantial increases in locomotor activity. Little or no headweaving, stereotypy or ataxia was observed after intra-accumbens injections of PCP. In the third experiment, systemic administration of 0.4 mg/kg haloperidol significantly reduced the locomotor activity induced by intra-accumbens injection of 15.0 micrograms PCP. These results indicate that PCP can increase extracellular levels of DA by direct actions in the DA terminal region, and that these effects are related to some of the behavioral stimulant properties of PCP.


Cholinergic and GABAergic neurons occur in both the distal and proximal turtle retina.

Turtle retinas were processed immunocytochemically and histochemically to detect the presence of choline acetyltransferase (ChAT), acetylcholinesterase (AChE), and glutamate decarboxylase (GAD). We observed cholinergic and gamma-aminobutyric acid (GABA)ergic neurons in the proximal retina, as expected, and in the distal retina as well. ChAT immunoreactivity in the distal retina was observed within the axons and pedicles of numerous cone photoreceptors, suggesting that a population of turtle cone photoreceptors uses ACh as a neurotransmitter. Type L2 horizontal cells were immunoreactive for GAD, and their dendrites invaginated into cone pedicles. AChE histochemistry revealed processes within the outer plexiform layer which formed a loosely organized lattice. In the proximal retina, labeling for ChAT and GAD was similar to that reported by previous investigators. Processes from ChAT-labeled amacrine cells in the inner nuclear layer formed a stratum within the distal inner plexiform layer (IPL) (at 16-21% relative IPL depth), and processes from ChAT-labeled amacrines in the ganglion cell layer formed a proximal ChAT stratum (at 55-58% relative IPL depth). In addition, six AChE-labeled bands and five GAD-labeled bands were observed within the IPL of stained retinas. Therefore, we determined that the two broadest AChE-labeled bands and the two broadest GAD-labeled bands overlapped the two labeled ChAT strata. The evidence for cholinergic and GABAergic processes in both the inner plexiform layer and the outer plexiform layer, combined with electrophysiological evidence from other investigators, raises the possibility that distal retinal neurons may be involved in the encoding of directional information.


Overlap between acetylcholinesterase-rich and choline acetyltransferase-positive (cholinergic) axons in human cerebral cortex.

The distribution of acetylcholinesterase-rich axons was compared to that of choline acetyltransferase-positive (cholinergic) axons in 28 major cytoarchitectonic divisions of the adult human cerebral cortex. Acetylcholinesterase-rich as well as choline acetyltransferase-positive cortical axons contained multiple varicosities. Each type of axon was more densely distributed in limbic-paralimbic regions of the brain. In all the cortical areas that were examined, the two markers displayed laminar and regional distribution patterns that were indistinguishable from each other. A method that allowed the concurrent visualization of both reaction products demonstrated that acetylcholinesterase and choline acetyltransferase were colocalized in the same axon. These observations show that there is probably a complete correspondence between choline acetyltransferase-positive and acetylcholinesterase-rich axons and that the acetylcholinesterase reaction can be used as a specific marker for cortical cholinergic axons in the adult human brain.


Somatotopic maps within the zona incerta relay parallel GABAergic somatosensory pathways to the neocortex, superior colliculus, and brainstem.

Neurons located in the zona incerta (ZI) of the ventral thalamus project to several regions of the central nervous system, including the neocortex, superior colliculus, and brainstem. However, whether these projections are functionally segregated remains unknown. This issue was addressed here by combining neuroanatomical tracers with immunohistochemical staining for gamma-aminobutyric acid (GABA) and/or parvalbumin, coupled with neurophysiological mapping. GABAergic projection neurons were found in four distinct subregions of the ZI including: (1) the rostral pole of the ZI, from which neurons project to the supragranular layers of the neocortex (especially layer I); (2) the dorsal subregion of the ZI, where both ascending projections to the neocortex and descending projections to the pretectal area were observed; (3) the ventral subregion of the ZI, whose neurons project to the superior colliculus; and 3) the caudal pole of the ZI, from which descending projections to the lower brainstem and spinal cord were observed. Somatotopic representations of the contralateral cutaneous periphery were also identified in the dorsal and ventral subregions of ZI, both of which were found to receive dense direct afferent projections from the trigeminal complex, and dorsal column nuclei. These results suggest that the rat ZI is a major somatosensory relay in the ventral thalamus, carrying feed-forward inhibitory signals to neocortical and subcortical targets, in parallel with the excitatory somatosensory pathways.


NPY-like immunoreactivity in sensory nerve fibers in rat sciatic neuroma.

Neuropeptide Y (NPY)-like immunoreactivity was examined by fluorescence immunohistochemistry in rat sciatic neuromas, L5 dorsal root ganglias (DRGs) and L5 dorsal roots 1-3 weeks after chronic nerve injury. Anterograde tracing demonstrated that a large number of NPY-positive neuroma fibers were sensory. These fibers were mostly large diameter axons, in line with the finding that a majority of NPY-immunoreactive neurons in the DRG were medium- to large-sized neurons which showed immunoreactivity to the neurofilament antibody RT 97. In dorsal roots NPY immunoreactivity was strong after sciatic neuroma formation. Dorsal rhizotomy and ligation, on the other hand, did not induce NPY immunoreactivity at any of the sites examined.


Inhibitory neuron produces heterosynaptic inhibition of the sensory-to-motor neuron synapse in Aplysia.

We have identified an inhibitory neuron (RPL4) in the right pleural ganglion of Aplysia, which produced hyperpolarization of the sensory and motor neurons involved in the tail withdrawal reflex. Activation of RPL4 significantly reduced the amplitude of excitatory postsynaptic potentials produced in tail motor neurons by action potentials triggered in sensory neurons. This example of heterosynaptic inhibition was due, at least in part, to an increase in membrane input conductance in the motor neuron. Since the synaptic strength of the sensory-to-motor neuron connection has been associated with the strength of the tail withdrawal reflex, RPL4 may contribute to modulation of that reflex.


Angiotensin II excites vasomotor neurons but not respiratory neurons in the rostral and caudal ventrolateral medulla.

We examined the vasomotor and respiratory effects of angiotensin II microinjection into the rabbit ventrolateral medulla (VLM). Angiotensin II in the rostral and caudal VLM increased and decreased arterial pressure, respectively, but had no effect on phrenic nerve activity. In contrast, L-glutamate injections in the same areas altered both arterial pressure and phrenic nerve activity. The results suggest that angiotensin II may activate specifically vasomotor neurons but not respiratory neurons in the VLM.


Repeated stress enhances vasopressin synthesis in corticotropin releasing factor neurons in the paraventricular nucleus.

The effect of repeated stress on corticotropin-releasing factor (CRF) and vasopressin (AVP) synthesis in parvocellular neurons of the paraventricular nucleus (PVN) was studied by means of double label immunocytochemistry. Once daily immobilization of male rats for 16 days leads to a 75% increase in the number of CRF immunoreactive neurons, but a 5-fold elevation in the number of AVP containing CRF cell bodies. These results demonstrate that repeated stress activates AVP synthesis in CRF neurons.


Transient c-fos expression and dendritic spine plasticity in hippocampal granule cells.

A transient expression of Fos protein occurs in nuclei of partially deafferented dentate granule cells within 1 h of transecting perforant path and fornix inputs. This was followed within 24 h by widening of spine necks, elaboration of the spine apparatus, and appearance of coated vesicles, multivesicular bodies, and ribosomes in remaining spines. This study supports the hypothesis that immediate early genes such as c-fos activate late response genes for generating building blocks of plasticity in partially deafferented neurons of adult rats.


Fine structure and possible origins of nerve fibers with corticotropin-releasing factor-like immunoreactivity in the rat central amygdaloid nucleus.

The fine structure of nerve fibers with corticotropin-releasing factor (CRF)-like immunoreactivity in the central amygdaloid nucleus and CRF-containing afferents to the nucleus were investigated by pre-embedding immunoelectron microscopy and by the combination of fluoro-gold tracing and the indirect immunofluorescence method. Significant numbers of CRF nerve endings and dendrites formed synapses with non-immunoreactive dendrites and axon terminals, respectively. Axon terminals devoid of CRF frequently made synapses with the soma of immunoreactive and non-immunoreactive neurons; CRF nerve endings in contact with the soma were fewer in number. Occasionally, CRF was localized to both pre- and postsynaptic structures in the central amygdaloid nucleus. After fluoro-gold injection into the central amygdaloid nucleus and adjacent areas, double-labeled cells with the tracer and CRF were observed mainly in the lateral hypothalamic area and occasionally in the dorsal raphe nucleus, and they were less numerous than single-labeled cells. These findings suggest that part of the CRF axon terminals identified in the electron micrographs arises from neurons in the lateral hypothalamic area and the dorsal raphe nucleus and the others from intra-amygdaloid CRF neurons. The immunoreactive dendrites are likely to derive from neurons in the central amygdaloid nucleus, which are shown to send axons to the lower brainstem. Thus, this study demonstrates that CRF structures constitute a more complex neuronal network in the central amygdaloid nucleus than previously considered.


Low magnesium-induced epileptiform discharges in guinea pig hippocampal slices: depression by the organic calcium antagonist verapamil.

The antiepileptic effects of the organic calcium channel blocker verapamil were tested in non-drug-induced epileptiform activities. Low Mg2+ epileptic field potentials (EFP) were elicited in hippocampal slices of guinea pigs. Verapamil reduced frequency of occurrence and amplitude of EFP until EFP failed. The EFP reappeared if verapamil was withdrawn from low Mg2+ solution. Elevating the KCl concentration from 4 to 8 mM resulted in shortening of the latency of EFP abolition by verapamil and prolongation of the depressive effects of verapamil following its withdrawal. The findings indicate that transmembraneous calcium fluxes play also an essential role in low Mg(2+)-induced epileptiform activities.


Convulsive seizures in rats induced by N-methyl-D-aspartate injection into the massa intermedia.

The behavioral and electroencephalographic effects of N-methyl-D-aspartate (NMDA, 25 nmol/1 microliter) injection into the massa intermedia (MI) was examined in rats. The injection caused violent running/jumping and shrill vocalization without evidence of EEG seizure in the hippocampus (HP) and amygdala (AM). Animals with the injection site located in the reuniens nucleus subsequently developed generalized tonic and then clonic seizure, leading to fatal status epilepticus in some animals. Intermittent or continuous EEG discharge in the limbic system was found during clonic seizures. These findings suggest that the NMDA receptor in the reuniens nucleus in the MI participates in the generation and expression of convulsive seizure in rats.


Ischemia-induced irreversible deficit of memory function in gerbils.

Ischemia for 5 min temporarily increased locomotor activity in gerbils after 1 and 3 days. Temporary increases were also noted within 7 and 5 days after 20-min ischemia and repeated ischemia (three 2-min ischemia at 1-h intervals), respectively. In a passive avoidance task, gerbils were trained 2 or 14 days before the occlusion and then tested 1 day after it. Shortened step-through latency was observed in the retention test 3 days after 5-min ischemia, but not after 15 days (reversible deficit). In contrast, following 20-min ischemia, the step-through latency was significantly lower after 3 days and also after 15 days (irreversible deficit). Working memory was also tested with gerbils trained for an 8-arm radial maze task. A significantly higher working error was observed 1 day after 5-min ischemia but not after 5 days (reversible deficit). However, ischemia for 20-min and repeated ischemia led to markedly increase working error 1 day after the occlusion, with significant increases even after 14 and 28 days (irreversible deficit). In addition, while 5-min ischemia occurred the neuronal death in the hippocampal CA1 subfield, 20-min ischemia produced it not only in the CA1 subfield but also in the CA2-4 subfield and dorsal striatum. These results indicated that 5-min ischemia led to a reversible memory deficit, while 20-min and repeated ischemia produced an irreversible deficit.


Preferential uptake of rubidium from extracellular space by glial cells compared to neurons in leech ganglia.

Glial cells play a significant role in maintaining extracellular space (ECS) potassium (K) by temporarily buffering or accumulating excess ECS K and then returning that K to neurons. Yet, little is known about the relative affinity of neurons or glial cells for K when both cells are simultaneously exposed to the same ECS K, in situ. Also, the process by which glial cells return K to neurons remains unknown. Therefore, electron probe X-ray microanalysis was used to measure rubidium (Rb) uptake, as a K tracer, into leech packet neurons and glial cells, and to measure the distribution of cell water content, K, Na and Cl. When ECS Rb was increased from 4 mM to 20 mM, there was a clear preferential Rb uptake into glial cells compared to neurons. At 4 mM extracellular Rb there was only a small difference between uptake velocity of neurons and glial cells (maximum mean uptake velocity at 4 mM Rb was 1.09 for glia, and 0.41 mmol Rb/kg dry wt/s for neurons), whereas at 20 mM extracellular Rb, glial uptake velocity was dramatically greater than of neurons (max. mean Rb uptake velocity for glia was 4.3 compared to 1.47 mmol Rb/kg dry wt/s for neurons). Glial Rb uptake velocity was enhanced by low temperature (max. mean Rb uptake velocity at 20 mM ECS Rb at 6 degrees C was 6.04 for glia compared to 0.78 mmol Rb/kg dry wt/s for neurons) and by substitution of Cl with isethionate (max. mean Rb uptake velocity was 10.6 for glia compared to 1.33 mmol Rb/kg dry wt/s for neurons).(ABSTRACT TRUNCATED AT 250 WORDS)


Electroacupuncture modifies the expression of c-fos in the spinal cord induced by noxious stimulation.

The present study was designed to investigate the effect of 4 Hz vs. 100 Hz electroacupuncture (EA) on c-fos expression in the spinal cord induced by noxious stimulation (NS). A second objective was to evaluate the sensitivity of these two different frequencies of EA stimulation to the opiate antagonist, naloxone. Mechanical NS was applied to the right hindpaw following 30 min of either 4 Hz or 100 Hz EA treatment and the resulting c-fos expression in the spinal cord dorsal horn was compared to that obtained in rats exposed only to the noxious stimulation. The involvement of endogenous opioids in the EA response to 4 Hz or 100 Hz stimulation frequencies was evaluated by pretreating rats with naloxone (5 mg/kg, i.p.) 10 min prior to EA. Both 4 Hz and 100 Hz EA reduced the number of c-fos-immunoreactive neurons in the spinal dorsal horn induced by noxious stimulation by 58% and 50%, respectively. The suppression of c-fos expression induced by 4 Hz EA was completely reversed by prior treatment with naloxone. On the other hand, the suppression of c-fos induced by 100 Hz EA was only partially blocked by this opiate antagonist. These data indicate that both high- and low-frequency EA are capable of inhibiting the expression of c-fos in the dorsal horn induced by NS. Low-frequency EA appears to be mediated primarily by endogenous opioid systems, while non-opioid mechanisms may be involved in mediating the analgesic effect of high frequency EA. These results support the hypothesis that EA has a direct inhibitory effect on spinal cord dorsal horn neurons and extend the results of previous studies which indicate low frequency EA is mediated by opiate sensitive circuitry, while high frequency EA is predominantly mediated by non-opioid neurotransmitters.


Basic fibroblast growth factor-like immunoreactivity in the trigeminal proprioceptive and motor systems.

Basic fibroblast growth factor (bFGF) isolated from the brain and pituitary, has been shown to induce cell divisions in a variety of cell types. It also acts as a potent stimulator of angiogenesis, and it is important in the survival of several types of cultured neurons. Despite considerable information on the functions of bFGF, there is incomplete knowledge about the ways in which it reaches remote tissues and its subcellular localization in the adult brain. Here we report our findings that a certain population of neurons with free ribosomes and rough endoplasmic reticulum immunoreactive for bFGF in the mesencephalic nucleus of the trigeminal nerve sends proprioceptive fibers to muscle spindles in the masseter muscle, and immunoreactive axons to the trigeminal motor nucleus to form synapses with the bFGF-containing motoneurons whose axons further constitute myoneural junctions in the periphery. Moreover, some bFGF neurons contain electron dense immunoreaction deposits in the euchromatin but not in the heterochromatin of the nucleus. These findings suggest that endogenous bFGF is transported within nerve processes and functions in mature neuronal circuits subserving the masseteric reflex arcs, and that bFGF is produced in free ribosomes and/or rough endoplasmic reticulum and is transported into the genetically active euchromatin as well.


Comparison of the effects of chronic water deprivation and hypertonic saline ingestion on cerebral protein synthesis in rats.

The effects of 3 days water deprivation and 3 days with 2% (w/v) NaCl in drinking water on local rates of methionine incorporation into brain proteins were compared by means of a quantitative autoradiographic method with L-[35S]methionine. The two conditions of chronic dehydration resulted in large increases in the rate of methionine incorporation in the supraoptic (SON), magnocellular paraventricular (mPVN) and arcuate nuclei of the hypothalamus, and in the subfornical organ (SFO). Significant increases of lower amplitude occurred as a result of both treatments in the anteroventral third ventricle area, parvocellular paraventricular nucleus and locus coeruleus. Water deprivation caused larger increases of protein synthesis than hypertonic saline ingestion in the SON, mPVN and SFO. These results indicate that following chronic dehydration, increases in protein synthesis occur mainly in forebrain areas involved in the regulation of water balance, whereas no major changes in protein synthesis occur in brainstem areas involved in the control of blood volume and pressure.


Effects of intra-ischemic blood pressure on outcome from 2-vessel occlusion forebrain ischemia in the rat.

Halothane anesthetized Sprague-Dawley rats underwent 10 min of bilateral carotid artery occlusion with mean arterial pressure (MAP) held at 30, 50 or 60 mmHg. Sham rats did not undergo ischemia. A 7-day recovery interval was allowed. Intra-ischemic electroencephalographic (EEG) changes, behavioral function (Days 5-7), and histologic injury (Day 7) were evaluated. Under similar conditions, cerebral blood flow was determined after 10 min ischemia by the [3H]nicotine indicator fractionation technique. EEG isoelectricity was observed in 11 of 11, 5 of 10, and 2 of 11 rats in the 30 mmHg, 50 mmHg, and 60 mmHg groups respectively. Neither passive avoidance cross-over latencies nor general motor scores were affected by intra-ischemic MAP and no differences from sham performance were observed. The per cent of CA1 neurons counted as dead (left and right hemispheres combined) was significantly affected by intra-ischemic MAP (72, 46 and 28% in the 30 mmHg, 50 mmHg, and 60 mmHg groups, respectively; P less than 0.001). A greater than 50% CA1 neuronal mortality rate was present only in those rats exhibiting EEG isoelectricity. However, the number of rats demonstrating greater than a 25% interhemispheric difference in CA1 neuronal loss was greatest in the 50 mmHg group (P less than 0.02). Hippocampal blood flow decreased in association with severity of hypotension (8 +/- 1, 35 +/- 8, and 48 +/- 2 ml/100 g/min (mean +/- S.E.M.) for 30, 50, and 60 mmHg, respectively; P less than 0.01). Again, however, the greatest variability in blood flow was observed at MAP = 50 mmHg.(ABSTRACT TRUNCATED AT 250 WORDS)


Rapid changes in ascorbate and dopamine release in rat nucleus accumbens after intracerebroventricular administration of NMDA.

In vivo voltammetry at electrochemically pretreated carbon fibre electrodes was used to investigate the effect of intracerebroventricular (i.c.v.) administration of N-methyl-D-aspartic acid (NMDA) on neuronal activity in rat nucleus accumbens. Infusion of a low dose of NMDA (1 nmol) was followed a few minutes later by rapid changes in both Peak 1 and Peak 2 heights indicating large but short-lived increases in the extracellular concentrations of ascorbate and catecholamines, respectively. These responses did not seem to be dependent on the dose infused since infusion of NMDA for a longer time period neither changed the amplitude nor the time-course of these effects. The increase in Peak 2 height was resistant to pargyline pretreatment indicating that this response mainly reflected the release of dopamine. The administration of NMDA was followed by behavioural activation in the animals but not convulsions. Co-administration of the competitive NMDA receptor antagonist, CPP (1 nmol), completely blocked these effects while the acetylcholine receptor antagonist, atropine (1.5 nmol), and the GABA receptor antagonist, picrotoxin (1 nmol), failed in this respect. The phenomenon spreading depression is discussed as a possible explanation of these results.


In vivo protection of striatum from MPP+ neurotoxicity by N-methyl-D-aspartate antagonists.

The present study was designed to assess by microdialysis whether N-methyl-D-aspartate (NMDA) non-competitive receptor antagonist, MK-801, is able to protect dopaminergic neurons against 1-methyl-4-phenylpyridinium ion (MPP+) neurotoxicity. An intraperitoneal injection of MK-801, 10 mumol/kg, half an hour before striatal MPP+, 10 mM, perfusion did not protect against its neurotoxicity. Afterwards, rats received an intraperitoneal injection of MK-801 every 4 h, during 24 h. Under these conditions, one day after MPP+ perfusion, DA basal extracellular levels were close to the detection limit of our HPLC equipment in both control and MK-801 treated rats. 3,4-Dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) basal output were lower in the former than in the latter rats. A second MPP+ perfusion statistically increased extracellular levels of DA and decreased DOPAC and HVA output in both groups of rats. However, the increase in extracellular DA overflow was higher in MK-801 treated rats than in the control group, indicating a higher number of surviving dopaminergic terminals. These results suggest that MK-801 is not able to protect against the primary direct neurotoxic action of MPP+, but a second MPP+ neurotoxic action mediated by excitatory amino acids could be partially prevented by MK-801.


Limited and selective adduction of carboxyl-terminal lysines in the high molecular weight neurofilament proteins by 2,5-hexanedione in vitro.

2,5-Hexanedione (2,5-HD) induces a toxic neuropathy characterized by massive, focal axonal neurofilament (NF) accumulation. Covalent interaction of 2,5-HD with NF protein amines, resulting in pyrrole adduct formation, has been proposed as a critical step in its mechanism. The present study was undertaken to evaluate the hypothesis of selective 2,5-HD/lysine modification, by quantitating in vitro adduction in the NF proteins and in specific polypeptide domains of each protein. Native rat spinal cord NFs were exposed to 0-212.5 mM [14C]2,5-HD for 2-16 h (37 degrees C under argon), followed by removal of non-covalently bound radioactivity. Incorporation of radioactivity and pyrrole formation in NFs increased linearly with 2,5-HD concentration and biphasically with time. SDS-PAGE and fluorography demonstrated prominent labeling of the three NF subunit proteins (H, M, and L), in addition to high-MW, crosslinked material derived from NF-H and -M. Mild chymotryptic cleavage was employed to isolate the carboxyl-terminal 'tail' domains of NF-H and -M, and the pooled amino-terminal NF 'rod' regions, all of which were radiolabeled. Specific activity (mol adduct/mol protein) of adducted NF proteins and polypeptide domains was determined by scintillation counting of electroeluted proteins. Stable binding in the NF-H and -M proteins was 4- to 6-fold higher than in the NF-L protein at all 2,5-HD concentrations, with specific activities of approximately 6.9, 4.7, and 1.3 mol/mol protein, respectively, at 212.5 mM. Approximately 70-80% of NF-H and -M binding was localized to the tail domains. In contrast, NF-L and pooled rod domain adduction did not substantially exceed 1 mol/mol protein. These findings provide the first direct evidence for limited and selective pyrrole adduction in the NF proteins following 2,5-HD exposure.


Effects of dihydroergotoxine on central cholinergic neuronal systems and discrimination learning test in aged rats.

We evaluated changes in the cholinergic neuronal system and learning ability with aging. Choline acetyltransferase (ChAT) activity, a presynaptic index of the cholinergic system, was decreased in the cerebral cortex, hippocampus, striatum, and hypothalamus in the brain of aged rats compared with young adults. Muscarinic cholinergic binding sites (receptors, MCR), a postsynaptic index of the cholinergic system, were markedly decreased in all areas of the brain. However, intraperitoneal injection of 1 mg/kg of dihydroergotoxine (DHET) for 14 days normalized both ChAT and MCR in the cerebral cortex and hippocampus. In the striatum, ChAT was normalized, but MCR did not recover. Aged rats showed marked learning impairment in a 30-day operant type brightness discrimination learning test. Daily DHET administration restored the discrimination ability in the aged rats to nearly the young adult level. DHET had no effects on central cholinergic indices or learning test results in young adult rats. These findings suggest that learning is impaired in aged rats due to impairment in the central cholinergic neuronal system, and that DHET normalizes the decreased function in this system, restoring the learning ability.


In vivo effects of beta-amyloid implants in rodents: lack of potentiation of damage associated with transient global forebrain ischemia.

Recent studies have shown that the principal component of the senile plaque in Alzheimer's disease (AD), beta-amyloid protein (beta AP) can exert direct and indirect neurotoxicity in vitro. Because of the studies that demonstrated potentiation of excitatory amino acid toxicity by beta AP, we decided to test whether beta AP was able to potentiate damage in an in vivo model where excitotoxic damage is thought to be important. The present study evaluated the in vivo effects of beta AP implants in the brain of rats before and after being subjected to 10 min of transient global forebrain ischemia by 4-vessel occlusion (4-VO). Implants of either synthetic beta AP or prolactin (PRL), which was used as a control protein, were made into the striatum and the hippocampus of either the left (beta AP) or the right (PRL) cerebral hemisphere. The implants were made in a lipophilic, non-toxic vehicle so as to try and achieve sustained beta AP exposure. One group of animals was evaluated for direct in vivo effects within 1 week following implantation; the other group was subjected to 4-VO 3-4 days post-implantation for evaluation of potential indirect effects. This latter group was compared to the histopathology of animals subjected to 4-VO without prior implantation. In the group of animals evaluated for direct effects, no evidence of neurotoxicity was observed. Bielschowsky silver staining and immunostaining for ubiquitin were unremarkable in all lesions. beta AP was detected by immunocytochemistry in the parenchymal tissue that received beta AP implants. Marked glial activation was observed to be associated with experimental and control implants. Under the experimental conditions employed in this study, significant protection from ischemia rather than potentiation of damage was observed. These results suggest that beta AP may not be neurotoxic in rodents in vivo and that the lesions and/or trauma produced by the implantation procedure 3-4 days prior to 4-VO may have induced factors that were protective against ischemia-induced damage.


In vivo intracellular correlates of hippocampal formation theta-on and theta-off cells.

Using urethane-anesthetized rat, intracellular recordings were made in hippocampal formation cells classified according to previously established criteria as either theta-on or theta-off, in order to further define the electrophysiological characteristics of these cells. Four cells classified as phasic theta-off cells had short duration spikes (less than 1 ms), high input resistances (54-61 M omega) and large fast afterhyperpolarizations (6-10 mV), thus sharing some of the properties of identified hippocampal interneurons. Phasic theta-off cells also exhibited rhythmic membrane potential oscillations (MPOs) ranging from 4 to 10 mV in amplitude during the simultaneous occurrence of extracellular theta field activity, but not during the occurrence of large amplitude irregular field activity (LIA). The MPOs of phasic theta-off cells were the same frequency as and were highly coherent with the extracellular theta field activity. In all four phasic theta-off cells the positive peak of the MPO was in phase with the positive peak of the local theta field activity. At the onset of extracellular theta field activity above 4-5 Hz, the membrane potentials of phasic theta-off cells showed a 5-10-mV hyperpolarizing shift, accompanied by MPOs without spike discharges. As theta frequency slowed down there was a return to baseline membrane potential levels and spike discharges occurred near the positive peak of the MPOs. The seven cells classified as phasic theta-on had longer duration spikes (greater than 1 ms), lower input resistances (22-36 M omega) and small (approx. 1.0 mV) fast afterhyperpolarizations, thus sharing some of the properties of hippocampal projection cells.(ABSTRACT TRUNCATED AT 250 WORDS)


Adrenalectomy or metyrapone-pretreatment abolishes cerebral metabolic responses to the serotonin agonist 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI) in the hippocampus.

1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), a serotonin type 2 (5-HT2) agonist, elevates plasma corticosterone levels and reduces the cerebral metabolic rate for glucose (rCMRglc) in the hippocampus, a structure which possesses few 5-HT2 receptors but a large number of steroid receptors. To explore the hypothetical interaction between 5-HT and steroid mechanisms in the hippocampus, we measured rCMRglc in intact, adrenalectomized and metyrapone-pretreated rats after saline or DOI administration. Metyrapone pretreatment alone had no significant effect on rCMRglc, but adrenalectomy produced widespread rCMRglc increases in the cortex, hippocampus and monoaminergic brainstem nuclei. In intact rats, DOI 10 mg/kg reduced rCMRglc in limbic areas and increased it in the interanteromedial and paracentral thalamic nuclei. Metyrapone pretreatment and adrenalectomy abolished rCMRglc responses to DOI in hippocampal areas and enhanced those in thalamic nuclei. These results indicate that brain responses to DOI are dependent upon the functional state of the hypothalamus-pituitary-adrenal cortex axis.


Effects of anticonvulsant drugs on axonal conduction in mammalian corpus callosum.

The frequency-dependent effect of various anticonvulsant drugs on the conduction in central axons was studied in the corpus callosum of rat and guinea pig brain slices from the parietal region. Extracellularly recorded compound action potentials (CAPs) were evoked by either single stimulus or high frequency stimulation (40-80 Hz). The CAP in rats consisted of an early component (fast axons, 1.2-1.8 m/s) and a late component (slow axons, 0.5-0.7 m/s), while in the guinea pig only the slow phase was observed. Diphenylhydantoin increased the latency of a single response by 10%, and had no effect on the CAP amplitude. In contrast, both phenobarbital and pentobarbital reduced the amplitude of singly evoked CAPs. Stimulation at high frequency alone decreased the CAP amplitude by 10-20%. Identical stimulation in the presence of the drugs further suppressed the CAP amplitude by an additional 31%, with varying degree of drug efficacy. The depressant effect was significant for the slow axons but the fast axons were virtually unaffected by any of the drugs. The results are consistent with the hypothesis that the antiepileptic drugs DPH, Phe and Pnt may block axonal conduction from an epileptic focus into neighbouring areas of the brain.


Age-dependent changes in cat masseter nerve: an electrophysiological and morphological study.

The present study was undertaken to determine the manner in which aging affects the function and structure of the masseter nerve in old cats. Electrophysiological data demonstrated a significant decrease in the conduction velocity of the action potential in old cats compared with that observed in adult cats. Light microscopic analyses revealed an age-dependent decrease in axon diameter. Electron microscopic observations of the masseter nerve in the aged cats revealed a disruption of the myelin sheaths and a pronounced increase in collagen fibers in the endoneurium and perineurium. These morphological changes are discussed and then related to the decrease in conduction velocity which was observed in the electrophysiological portion of this study.


The role of angiotensin, AT1 and AT2 receptors in the pressor, drinking and vasopressin responses to central angiotensin.

Angiotensin II (Ang II) given centrally produces an increase in blood pressure and motivation to drink. The physiological mechanisms that mediate the pressor response include release of vasopressin (AVP) and activation of the sympathetic nervous system. Using 2 new Ang II receptor antagonists, we were able to investigate the role of AT1 or AT2 receptors in mediating these effects. Adult male Sprague-Dawley rats were cannulated in the lateral ventricle and 5 days later catheterized in the carotid artery for blood pressure measurements. All experiments were carried out in conscious rats. Three treatments were given intraventricularly (i.v.t.), in 2 microliters artificial cerebrospinal fluid (ACSF) at 30 min intervals: (1) 50 ng Ang II, (2) 0.7 micrograms AT1 antagonist Losartan or 7.0 micrograms AT2 antagonist PD123177, followed by 50 ng Ang II, and (3) 50 ng Ang II, to test for recovery. Blood pressure and drinking measurements were recorded. Also, blood samples for assay of AVP were drawn at 1 or 3 min post-injection in 2 separate groups of rats. We found that both Losartan and PD123177 significantly reduced release of AVP to Ang II 1 min post-injection. Losartan significantly blocked the pressor response (P less than 0.001), while PD123177 had no significant effect. Drinking was also antagonized by Losartan (P less than 0.05) and reduced (n.s.) by PD123177. The results suggest that the pressor response to Ang II (i.v.t.) is predominantly AT1 mediated, while the drinking and AVP responses may be mediated by both receptor subtypes.


Absence of early destructive changes of cytoskeletal proteins after transient ischemia in the rat.

We examined the changes in immunoreactivity of microtubuli-associated protein (MAP) 2 in dendrites by immunohistochemical analysis following 20 min of cerebral ischemia in the rat. A decrease of immunoreactivity of MAP 2 in dendrites in the CA1 subfield of the hippocampus was observed on days 3 and 7 but not on day 1 after ischemia. Early destructive changes of this protein were not observed, a finding which was confirmed by polyacrylamide gel electrophoresis analysis. We elucidated one factor which indicated that destruction of the dendrites of CA1 pyramidal neurons would not take place any earlier than the destruction of the neurons themselves after ischemia in rats.


Molecular cloning of two partial serotonin 5-HT1D receptor sequences in mouse and one in guinea pig.

The G protein coupled serotonin (5-HT) receptors, with seven membrane spanning domains, form a multigene family of which several members have been cloned and sequenced. The presence of 5-HT1D binding sites to our knowledge has not yet been reported in mouse. Here we describe the cloning and sequencing by the polymerase chain reaction (PCR) method of two 5-HT1D receptor sequences of the third cytoplasmic loop in mouse, strongly suggesting the existence of two 5-HT1D receptor genes, located on chromosome 4. A homologous sequence to one of them was cloned in guinea pig.


[Triiodothyronine is needed for the acclimatization of brown trout (Salmo trutta) or rainbow trout (Oncorhynchus mykiss) to seawater].

Brown and rainbow trout, held in freshwater at 13 +/- 1 degrees, were injected, every 3 days, with iopanoic acid (IOP: 5 mg/100 g body wt), an inhibitor of deiodination of thyroxine (T4) to triiodothyronine (T3). One group of IOP-treated rainbow trout was immersed in T3 (20 micrograms/l water). In IOP trout, plasma T3 fell to very low levels by day 7, while changes in T4 levels were less marked. In IOP + T3 trout plasma T3 increased fivefold, plasma T4 being unchanged. No mortality occurred and plasma osmolarity (OP) was not altered by any treatment. After direct transfer to seawater (30/1000), IOP trout were unable to acclimate to salinity: all died within 2 or 3 days, while the survival at day 3 was 100% in control brown trout and 45 and 74% in control and IOP + T3 rainbow trout respectively. OP increased more in IOP and less in IOP + T3 than in controls. There was a significant inverse correlation between T3, but not T4, plasma level, at the time of transfer and the OP 1 day later. In conclusion, although T3 does not play a significant role in osmoregulation in freshwater, T3 and therefore the deiodination of T4 into T3, were required for the development of hypo-osmoregulatory capacity involved in acclimation of trout to seawater.


[Demonstration of glutamate in primary sensory trigeminal neurons innervating dental pulp in rats].

Primary sensory trigeminal neurons supplying the dental pulp of incisors in rats were labelled by retrograde axonal transport. Using an auto-metallographic intensification procedure, 48 hrs. after injection of wheat-germ colloidal gold in the pulp, gold particles were detected in the cytoplasm of the neurons as black granulations. Glutamate was found in 45-60% of the neurons by submitting ganglion slices to an anti-glutamate immuno-serum revealed by immunocytochemistry. Among the neurons supplying the dental pulp of incisors by their peripheral process, 70% are Glu+, 30% Glu-. These observations suggest that the population of neurons supplying the dental pulp is not functionally homogeneous and that Glu- neurons use a different neurotransmitter. The coexistence of Glu+ and Glu- neurons could also indicate that glutamate expression is modulated during the life of these neurons.


[Specific induction by phorbol ester of the gene transcription and of the activity of ornithine decarboxylase in two control and transformed epithelial cell lines. Modulator effect of anti-inflammatory agents].

The mechanism of ornithine decarboxylase (ODC) induction by phorbol ester (TPA) has been studied in two permanent epithelial cell lines, a control (Ctr) and a Benzo (a) pyrene transformed line (BaP-tr); the degree of ODC gene expression (ODC-mRNA) was evaluated in comparison to the ODC activity. A small dose of TPA (4 x 10(-8) M) highly induced ODC activity in these cells. The induction levels differed however, corresponding respectively to 4:1 (induced: basal ODC) in Ctr cells and to 2:1 in BaP-tr cells. This difference reflected the variation of ODC gene expression; the ODC-mRNA induction was 6:1 in Ctr cells and 3:1 in BaP-tr cells. Repetitive TPA treatment decreased the ODC induction in these cells, as compared to that resulting from a single TPA treatment. Studies of ODC modulation were performed in presence of anti-inflammatory agents. In the two cell lines, Indomethacin (anti-cyclooxygenase) did not change the level of ODC induction by TPA. Nordihydroguaiaretic acid (NDGA, anti-lipoxygenase) inhibited this induced ODC. These results differed from that obtained in vivo in mouse skin. Dexamethasone (DXME, anti-phospholipase A2) showed different action according to treatment time. Used together with TPA (t0), DXME inhibited ODC induction by the carcinogen; with three hours delay after TPA (t3), DXME treatment stimulated ODC in the cells. This divergent action may be reproduced by Actinomycin D, while Cycloheximide only exhibited constant inhibition. Studies now in progress suggested that the inhibition of TPA induced ODC by DXME may reflect ODC gene repression, as for the stimulating effect it could be related to ODC post-transcriptional modulation, owing to the decrease of proteolytic action.


[Analysis of frequency of DR3 allele in rapidly evolutive forms of Crohn disease in adults; comparison with the occurrence of this allele in slowly evolutive forms and in the normal population].

This communication reports 1. the frequency of the DR3 allele among 86 patients exhibiting various evolutive courses of Crohn's disease (CD), diagnosed in the same hospital in Alsace, France, hospitalized at least once between 1964 and 1986 and followed for at least 1 year, 2. the frequency of the DR3 allele among a control population in the same area: 126 volunteers donors of bone marrow. The definition of the evolutive course was similar to the one published by Binder et al.: slow course (including: intermittent: "occurrence of symptom-free period(s) of at least one month's duration excluding period where the patient was in steroid treatment"; and inactive: "completely free of bowel symptoms during the year") as opposed to continuous evolution: "without symptom-free periods". The DR3 allele determination was established by classical serologic analysis. 26 patients were found with the DR3 allele; 14 belonged to the slow course group, 12 to the continuous evolution group; 60 patients did not exhibit the DR3 allele: 50 in the slow course group, 10 in the continuous evolution group. chi 2 = 8.28; p = 0.004. Therefore the frequency of the DR3 allele was very significantly higher in the group with the continuous course (55%) than in the slow course group (22%). Similarly the frequency of the DR3 allele in the group with the continuous course (12/22: 55%) was significantly higher than in the group of control subjects (34/126: 28%) chi 2 = 6.64; p = 0.01.(ABSTRACT TRUNCATED AT 250 WORDS)


[Inhibition of the tumoral growth induced by the injection of histo-incompatible cells producing interleukin-2].

In murine models, we show that the growth of a transplanted tumor can be controlled when allogeneic or xenogeneic cells expressing high levels of interleukin-2 are co-injected with the syngeneic tumor cells. Thus, genetically modified allogeneic or xenogeneic cells could have some therapeutic potential as vectors for transient cytokine gene expression.


[Influence of the distribution of the dose on carcinogenic effects of ionizing radiations of low lineal energy transfer on the thyroid tissue].

The frequency of thyroid nodules has been studied among 396 children irradiated for a hemangioma, from 1946 to 1973. 226Ra, 192Ir, 90Y, 32P, 90Sr, as well as X-rays had been used for treatments. The doses of radiation received by the thyroid of each child have been estimated retrospectively. The irradiations have been classified in two categories based on their duration: less than 30 min., and more than 30 min. The doses received with each of these two types of irradiation were summed for each patient. The risk of thyroid nodule increased as a function of the dose to thyroid only for the dose delivered with the short duration. This study emphases the importance of the role of the dose rate in the risk of radio-induced tumour.


[Demonstration of dissociation between frontal and temporal lesions in man on two versions of delayed non-matching recognition tests used in monkeys].

11 patients with frontal lobe lesions (F group), 9 patients with temporal lobe lesions (T group) and 18 normal control subjects (C group) were tested on two versions of the delayed non matching-to-sample task using either different pairs (DNMTS) or the same pairs of objects (RECURRENT) on successive test trials. The results revealed that the DNMTS task was sensitive to memory impairment but did not differentiate the two experimental groups. In contrast, the recurrent version of the task showed a dissociation between the two pathologies. Thus, whereas patients of group T exhibited an accelerated rate of forgetting as a function of the retention interval, patients of group F were impaired whatever the retention interval.


Gram-scale enzymatic synthesis of a peptide bond.

The synthesis reaction of the peptide, N-Cbz-L-tryptophanyl-glycineamide, catalyzed by alpha-chymotrypsin was performed in a 20% water/80%, 1,4-butanediol mixture. The synthesis yield reached 90.9% at the end of the reaction and 72.3% after purification. The effects on the yield of both pH and the ratio between total initial concentrations of glycineamide and N-Cbz-L-tryptophan are examined. The high yield, specificity, simplicity and reproducibility of this method make it complementary of the chemical methods.


[Expression, isolation and purification of antibody fragments fused to maltose-binding protein in Escherichia coli].

We have fused the variable domains of a mouse antibody to the C-terminal end of the maltose-binding protein (malE), at the genetic level. The hybrid proteins were expressed in E. coli under control of the malEp promoter, and exported to the periplasm, at low temperature. They were purified by affinity chromatography on cross-linked amylose. When the two variable domains were fused together through a peptide link, the hybrid displayed similar affinity and specificity to the antigen as the native antibody.


[IgG autoantibodies against cellular p72 antigen crossing with (MLV) p15-gag antigen: presence in early HIV 1 infection, in HBV infection and in primary Gougerot-Sjögren].

IgG antibodies of autoimmune SLE (Systemic Lupus Erythematosus) serum S detected a HeLa hnRNP 72 kDa protein, cross-reacting with the retroviral (MLV) p15-gag polypeptide. Since serum S disclosed a ubiquitous 72 kDa antigen in HeLa cell fractions, was prepared the so-called cytoplasmic "X fraction", enriched for the 72 kDa protein, defined here as p72. This autoantigen was detected by antibodies of HIV 1+ patients, recently of seroconverted (RSC) asymptomatic subjects, of HBV+ sera, and of primary Gougerot-Sjögren (prGS) sera. The presence of these autoantibodies in different autoimmune and infectious pathologies raises the question of the involvement of p72 in the immune processes and in the early HIV1 infection.


[Excretion of urea and ammonia and its effect on the acid-base balance of water in the habitat of the anuran amphibian Xenopus laevis. Action of metabolic alkalosis].

We studied in Xenopus laevis the effect of changing the salinity and the acid-base status of the ambient water on the total nitrogen catabolism and the nature of the nitrogen end products, urea and ammonia. Increase of the ambient osmolarity by addition of NaCl led to a rise in protein catabolism and to a predominant ureotelism which can approach 95% of the excreted nitrogen. The osmolarity can reach 500 mosmol. L-1 without obvious harmful effects. NaCl can then be replaced by NaHCO3 without injury to the animal as long as water alkalosis is avoided by an appropriate increase of the ambient CO2 tension, PCO2. However, if PCO2 is kept low, the resulting water metabolic alkalosis causes death within a few hours.


[Behavioral asymmetry in BALB/cCF mice with corpus callosum abnormalities].

The possible homology between anomalies of the corpus callosum in mice and in humans remains questionable. The small number of existing behavioural studies in mice have not shown effects, at the behavioural level, of the absence or reduction in size of the corpus callosum. We therefore examined the development, during the first 3 weeks of postnatal life, of a number of simple reflex and integrative responses in the members of a sample of 101 BALB/cCF mice; at autopsy carried out at 50 days of age, 29 mice showed anomalies of the corpus callosum (total absence or an area less than 0.75 mm2). Asymmetry of the development of these responses was measured either as the proportion of animals showing asymmetrical appearance of responses on the left and right sides, and as the delay between appearances on the left and right sides in "asymmetrical" mice. Both measures decreased over the first 15 postnatal days, at the same rate in normal and abnormal mice; in each case the decrease is better described by a second-order, quadratic, function than by a simple linear function. We therefore conclude that the integrity of the corpus callosum is not necessary for the normal maturation of sensorimotor behaviour in mice, and suggest that this conclusion may possibly be explained by the relatively recent appearance of mice in the mammalian radiation.


Sympathoadrenal system in neuroendocrine control of glucose: mechanisms involved in the liver, pancreas, and adrenal gland under hemorrhagic and hypoglycemic stress.

Glucose homeostasis is maintained by complex neuroendocrine control mechanisms, involving three peripheral organs: the liver, pancreas, and adrenal gland, all of which are under control of the autonomic nervous system. During the past decade, abundant results from various studies on neuroendocrine control of glucose have been accumulated. The principal objective of this review is to provide overviews of basic adrenergic mechanisms closely related to glucose control in the three peripheral organs, and then to discuss the integrated glucoregulatory mechanisms in hemorrhage-induced hypotension and insulin-induced hypoglycemia with special reference to sympathoadrenal control mechanisms. The liver is richly innervated by sympathetic and parasympathetic nerves. The functional implication in glucoregulation of sympathetic nerves has been well-documented, while that of parasympathetic nerves remains less understood. More recently, hepatic glucoreceptors have been postulated to be coupled with capsaicin-sensitive afferent nerves, conveying sensory signals of blood glucose concentration to the central nervous system. The pancreas is also richly supplied by the autonomic nervous system. Besides the well documented adrenergic and cholinergic mechanisms, the potential implication of peptidergic neurotransmission by neuropeptide Y and neuromodulation by galanin has recently been postulated in the endocrine secretory function. Presynaptic interactions of these putative peptidergic neurotransmitters with the classic transmitters, noradrenaline and acetylcholine, in the pancreas remain to be clarified. It may be of particular interest that it was vagus nerve stimulation that caused a dominant release of neuropeptide Y over that caused by sympathetic nerve stimulation in the pig pancreas. The adrenal medulla receives its main nerve supply from the greater and lesser splanchnic nerves. Adrenal medullary catecholamine secretion appears to be regulated by three distinct local mechanisms: adrenoceptor-mediated, dihydropyridine-sensitive Ca2+ channel-mediated, and capsaicin-sensitive sensory nerve-mediated mechanisms. In response to hemorrhagic hypotension and insulin-induced hypoglycemia, the sympathoadrenal system is activated resulting in increases of adrenal catecholamine and pancreatic glucagon secretions, both of which are significantly implicated in glucoregulatory mechanisms. An increase in sympathetic nerve activity occurs in the liver during hemorrhagic hypotension and is also likely to occur in the pancreas in response to insulin-induced hypoglycemia. The functional implication of hepatic and central glucoreceptors has been suggested in the increased secretion of glucose counterregulatory hormones, particularly catecholamines and glucagon.


Disparate effects of fenfluramine on thermogenesis in brown adipose tissue in the rat.

It has been suggested that fenfluramine, a clinically used appetite suppressant, can also promote weight loss by augmenting energy expenditure, as indicated by increased whole-body O2 consumption (VO2) and mitochondrial GDP binding in brown adipose tissue (BAT) of fenfluramine-treated rats. To further investigate a possible involvement of BAT in the drug's metabolic effects, 113Sn-labelled microspheres were injected into the left cardiac ventricle of conscious rats 70-80 min after intraperitoneal delivery of 20 mg/kg fenfluramine (DL-mixture) or saline vehicle. At 28 degrees C ambient temperature, fenfluramine augmented resting whole-body VO2 and increased the microsphere entrapment in BAT, indicating enhanced blood flow and metabolism. At 20 degrees C ambient temperature, the expected increase in BAT blood flow associated with nonshivering thermogenesis was observed in control rats, but in fenfluramine-treated rats the increase in BAT blood flow was severely attenuated, and VO2 and body temperature were reduced. The stimulatory effect of fenfluramine on BAT metabolism was not prevented by urethane anesthesia but did not occur if the tissue was denervated. These blood flow measurements corroborate previous reports, based on GDP-binding assays, that fenfluramine treatment can augment thermogenesis in BAT by effects mediated through the innervation of the tissue. However, the data also indicate that this calorigenic effect is dependent on ambient temperature being near thermoneutrality and that in a cool environment the drug inhibits BAT thermogenesis.


Conopressin G, a molluscan vasopressin-like peptide, alters gill behaviors in Aplysia.

Superfusion of an invertebrate vasopressin structural analogue, conopressin G, over the abdominal ganglion of an in vitro preparation of Aplysia californica has significant neurophysiological and behavioral effects. Both the amplitude of the siphon-evoked gill withdrawal reflux and concomitant activity in gill motor neurons are reduced in the presence of conopressin G. Moreover, the frequency of spontaneous gill movements and their neural correlate, interneuron II activity, are increased. These behavioral modifications strongly resemble those that occur during the food-aroused behavioral state in intact Aplysia. In addition, conopressin G superfusion reduces both the excitability of gill motor neurons and the strength of gill contractions in response to gill motor neuron discharges elicited by direct depolarizing current. A role for conopressin G or a similar peptide in the modulation of gill behaviors associated with the food-aroused state is suggested.


Rat atrial muscle responses with caffeine: dose-response, force frequency, and postrest contractions.

Caffeine has been reported to have a positive and (or) a negative inotropic effect on cardiac muscle. In this study, the force-frequency and postrest characteristics of rat atrium were studied in the presence of caffeine (1.0-10 mM) to see if the interval between beats affected the response of cardiac muscle to caffeine. When stimulation frequency was 0.5 or 2.0 Hz, there was a positive followed by a negative inotropic response with 1, 5, or 10 mM caffeine. Incomplete relaxation occurred under these circumstances, giving rise to contracture. At low frequency of stimulation (0.1 Hz) caffeine had only a negative inotropic effect, and this effect was greater with 1 mM caffeine than with 5 mM caffeine. In the absence of caffeine, when stimulation at 0.5 or 3 Hz was interrupted, a pause of 2-20 s resulted in potentiation. When caffeine was present (2.0 mM), postrest potentiation was severely attenuated, but the steady-state contraction amplitude within the range 0.5-3.0 Hz was not different. These results are consistent with the hypothesis that caffeine induces a leak of Ca2+ from the sarcoplasmic reticulum, and this Ca2+ is extruded from the cell, possibly by Na+/Ca2+ exchange. Sarcoplasmic reticular uptake of Ca2+ and the translocation to release sites appear not to be affected by caffeine within 1-5 mM concentrations.


Excitability of canine colon circular muscle disconnected from the network of interstitial cells of Cajal.

The 6 cpm omnipresent slow waves recorded in the circular muscle (CM) layer of canine colon are generated at the submucosal surface of the CM layer. After removal of the submucosal network of interstitial cells of Cajal (ICC), 66% of the CM preparations (25 of 38) were quiescent in Krebs solution. In the presence of carbachol, seven of nine of these spontaneously quiescent CM preparations demonstrated slow wave-like activity with mean frequency, duration and amplitude of 5.9 +/- 0.4 cpm, 2.8 +/- 0.5 s, and 0.8 +/- 0.2 mV, respectively. Similar slow wave-like activities were induced by TEA (seven out of eight quiescent CM preparations) with frequency, duration and amplitude of 6.1 +/- 0.2 cpm, 2.7 +/- 0.5 s, and 1.0 +/- 0.2 mV, respectively, and by BaCl2 (eight of eight quiescent CM preparations) with frequency, duration, and amplitude of 6.3 +/- 0.3 cpm, 1.8 +/- 0.2 s, and 0.5 +/- 0.1 mV, respectively. All the induced activities were abolished in the presence of 1 microM D600. CM preparations with the submucosal ICC network intact (ICC-CM) showed slow wave activity in Krebs solution at a frequency of 6.2 +/- 0.2 cpm, a duration of 3.6 +/- 0.2 s, and an amplitude of 1.0 +/- 0.1 mV (n = 22). When ICC-CM preparations were stimulated by BaCl2, carbachol, or TEA, the slow wave frequency did not change significantly, but the duration increased as well as the amplitude. In the presence of D600, the upstroke of slow waves remained and the frequency was not affected.(ABSTRACT TRUNCATED AT 250 WORDS)


Effect of pressure on circumferential order of adventitial collagen in human brain arteries.

A key factor in the contribution of collagen fibres to tissue mechanics is the alignment of the fibres, which we studied in brain arteries, focussing on alignment changes with distending pressure. Arteries from autopsy were cannulated and fixed at different distending pressures from 0 to 200 mmHg (1 mmHg = 133.32 Pa), alcohol dehydrated, paraffin embedded, sectioned, and stained for birefringent enhancement. The polarized light microscope was set for extinction and fibre orientations were precisely determined at the rotational position of extinction for 200 positions around the artery wall. Results from 22 arterial cross sections revealed, with fixation pressure, a significant but incomplete straightening of collagen (even at 200 mmHg). The mean angular deviation of alignment of fibres was +/- 30 degrees for arteries fixed at zero transmural pressure, which in contrast was +/- 7 degrees for the inner and +/- 13 degrees for the mid-adventitia for arteries fixed at 200 mmHg transmural pressure. We verified on vessels fixed at low pressure, by using a full wave plate in conjunction with the specificity of the interference colours, that the measurements were correct and not confused with angles at 90 degrees to the morphological axis. Alternative tissue processing was done with two arteries fixed at 120 mmHg and processed for frozen sections; the results showed diminished variability in alignment but within the range of measurements for wax embedded tissue. We concluded that the collagen fabric could contribute to the mechanics of brain arteries but that it would be with sinusoidal rather than straightened fibres of collagen.


Glibenclamide depresses the slowly inactivating outward current (ID) in hippocampal neurons.

Sulphonylurea drugs, such as glibenclamide and tolbutamide, are widely used as selective blockers of adenosine triphosphate-sensitive K channels. In experiments on hippocampal slices (from Wistar rats) glibenclamide (and possibly gliquidone and tolbutamide) significantly reduced the highly voltage-dependent, 4-aminopyridine-sensitive D-type outward current of CA3 neurons. Judging by these observations, the sulphonylureas may not be as selective as generally believed.


Direct evidence for nitric oxide formation from glyceryl trinitrate during incubation with intact bovine pulmonary artery.

It has been proposed that the mechanism of the vasodilator action of glyceryl trinitrate (GTN) involves biotransformation to nitric oxide. A sensitive chemiluminescence method for nitric oxide determination was used to test this hypothesis. In four experiments, bovine pulmonary artery (BPA) was incubated with GTN (0.1 mM) in Krebs' solution (2 mL) containing 30 mM KCl, and in anaerobic conditions using 95% Ar - 5% CO2, in a sealed micro-Fernbach flask (6.2-mL volume). After incubation for 2, 5, 10, or 20 min at 37 degrees C, 400-microL aliquots of headspace gas were removed and injected into a redox chemiluminescence detector. Nitric oxide formation was first measurable at 5 min (76 +/- 53 pmol/g wet wt. BPA), and increased with incubation time (174 +/- 46 pmol/g wet wt. BPA after 10 min and 310 +/- 67 pmol/g wet wt. BPA after 20 min). This is the first direct chemical measurement of nitric oxide formation during interaction of GTN with vascular smooth muscle. These data support the concept that GTN is a nitrovasodilator prodrug acting via the formation of nitric oxide.


Epiphytic populations of Pseudomonas syringae on barley.

The epiphytic populations of Pseudomonas syringae were monitored on 23 barley entries planted in the field in four replications during the summer of 1986, and on six selected entries during the summer of 1987, from the second-leaf stage until senescence. Populations were initially low (0-3 log colony-forming units (cfu) per leaf) in all but one entry; they generally increased throughout the season, and at the end they reached 3-7 log cfu/leaf. Significant differences among the average epiphytic populations were found in the 1986 trial; only one entry, however, had a significantly different average population in the 1987 trial. The slopes of population increase were also compared: significant differences were observed in 1986 but not in 1987. In addition to epiphytic population counts, the percentage of ice nucleation active bacteria was determined in the population isolated from each leaf sample, and averaged throughout the season for each entry. Significant differences were observed in 1986 and in 1987. When the entries were ranked according to their average epiphytic population and compared between the two experiments, they were found to be very similar. The same was not true for the other parameters studied in the experiment.


Evaluation of filamentous fungi isolated from petals of bean and rapeseed for suppression of white mold.

The influence of filamentous fungi isolated from petals of bean and rapeseed on white mold caused by Sclerotinia sclerotiorum was evaluated. In laboratory trials, macerates of agar plugs containing hyphal fragments of the pathogen in combination with individual fungi were applied onto celery petioles, and subsequent lesion diameters were recorded. The efficacy of 10 fungi exhibiting a spectrum of lesion suppression on celery was correlated with the efficacy of the same fungi in growth-room (r = 0.78, P = 0.005) and greenhouse (r = 0.68, P = 0.032) trials. From 315 isolates of fungi evaluated in the laboratory trials, the 10 most suppressive isolates were selected and evaluated in growth-room trials. Spores of the test fungi were applied onto flowers simultaneously with, and up to 24 h after, inoculation with ascospores of S. sclerotiorum. The most suppressive fungi included isolates of Alternaria alternata, Drechslera sp., Epicoccum purpurascens, Fusarium graminearum, Fusarium heterosporum, and Myrothecium verrucaria. These fungi did not provide consistent control of white mold of bean in a field test repeated four times in 1988. However, Drechslera sp. and E. purpurascens significantly reduced the incidence of white mold in one and two trials, respectively. Combination treatments of A. alternata and Benlate (1.1 kg active ingredient ha-1) suppressed white mold significantly more than either treatment alone in one of four trials.


Effects of culture conditions on the in vitro infection of fibroblasts by Candida albicans.

The effects of yeast culture age, carbon source, growth temperature, and germ-tube inducers on adherence to primary fibroblast cultures was studied in conjunction with the determination of adherence-mediated mammalian cell damage by measuring chromium-51 release from fibroblast monolayers. The results indicated that yeast culture age affected adherence only when the yeasts were grown at 37 degrees C, not after growth at 28 degrees C. At 37 degrees C, quantitatively fewer exponential-phase, glucose- or galactose-grown yeasts adhered to fibroblasts than did yeasts that were in lag or stationary phases. The reduced adherence correlated with less chromium-51 release and reduced germ-tube formation. The addition of germ-tube inducers, such as N-acetyl-D-glucosamine or serum, to exponential-phase yeasts caused an increase in germ-tube formation with a concomitant increase in yeast adherence and release of chromium-51 from the monolayers. Exponential-phase galactose-grown yeasts were more responsive to serum-induced germ-tube formation, germ-tube elongation, and fibroblast adherence than were exponential-phase glucose-grown yeasts. In addition, exponential-phase galactose-grown yeasts caused more chromium-51 release from monolayers in the presence of serum than did glucose-grown yeasts. Overall, conditions that enhanced germ-tube formation and elongation resulted in greatest adherence-mediated damage to the monolayers.