Hepatitis B virus infection in chimpanzees: titration of subtypes.

Thirty-four chimpanzees were inoculated with sera containing the adw, ayw, adr, or ayr subtype of hepatitis B surface antigen (HBs Ag). Twenty-nine of the animals became infected with hepatitis B virus, and in every instance the subtype of HBs Ag in the infected animal was the same as the subtype in the inoculum. Infectivity titers were established for the adw and ayw inocula. The patterns of serologic events varied in the infected animals but included most of the typical patterns of serologic change seen in human cases of type B hepatitis. Mild disease, manifested by elevated concentrations of serum enzymes and changes detected by liver biopsy, occurred in 23 of the 29 infected animals.


Induction of congenital hydrocephalus in hamsters with attenuated and natural strains of mumps virus.

The abilities of a low-passage strain and of a live, attenuated vaccine strain of mumps virus to induce congenital hydrocephalus in hamsters were tested by intraamniotic inoculation on the 10th day of pregnancy. Examination of term fetuses and neonates, with cytoplasmic inclusions, cytopathic effects, and specific immunofluorescence used as indicators, demonstrated an oronasal portal of entry for both strains. The vaccine strain appeared to be more pathogenic; it spread primarily into the respiratory tract and hence to the central nervous system. Inclusions were observed as long as 21 days after inoculation. Hydrocephalus and ependymal involvement, potentially capable of producing aqueductal stenosis, were observed in 19 of 81 animals studied 11-29 days after inoculation.


Experimental osteomyelitis. IV. Therapeutic trials with rifampin alone and in combination with gentamicin, sisomicin, and cephalothin.

Levels of rifampin, gentamicin, sisomicin, and cephalothin in normal and osteomyelitic rabbit bones were measured, and the efficacy of these drugs in the treatment of osteomyelitis was evaluated. Single drug regimens, including rifampin for 14 days and gentamicin, sisomicin, and cephalothin each for 28 days, were relatively ineffective (5%-33% sterile bone cultures). Rifampin, administered for 28 days, sterilized the bones of 55% of treated animals. The combination of gentamicin and rifampin, given for either 14 or 28 days, sterilized the bones of 67% of treated animals. The combinations of rifampin plus sisomicin and of rifampin plus cephalothin, given for 28 days, were significantly more effective than these agents alone, sterilizing 90%-95% of bones. The combination of rifampin, sisomicin, and cephalothin, given for only 14 days, sterilized the bones of all treated rabbits. Staphylococci isolated from the bones of therapeutic failures that had received rifampin alone or in combination with other antibiotics were highly resistant to rifampin (minimal inhibitory concentration, greater than 250 mug/ml), whereas the organisms recovered from animals not receiving rifampin remained sensitive. Results of in vitro studies of synergy and/or bactericidal activity of antibiotic combinations correlated with in vivo results in some, but not all, instances.


Cytotoxicity of Vibrio parahaemolyticus in HeLa cell culture.

In an investigation of the effect of Vibrio parahaemolyticus on epithelial cells in vitro, HeLa cells in slide culture chambers were inoculated with washed bacteria and several bacterial preparations. Preparations tested included live and heat-killed whole cells, unconcentrated culture filtrates, whole-cell lysates and their supernatant fluids, and supernatant fluids taken from HeLa cell monolayers previously inoculated with live bacteria. Slide cultures were evaluated at 3 and 5 hr by light microscopy and, in a few instances, by electron microscopy (live preparations) or at 24 hr by light microscopy (nonviable preparations). Live V. parahaemolyticus had a rapid cytotoxic effect that did not appear to be due to cellular invasion. The nonviable preparations had no effect on HeLa cells. The results demonstrate that V. parahaemolyticus is rapidly cytotoxic to epithelial cells in vitro and suggest that the presence of live organisms may be required for its enteropathogenicity.


Bioassay of metronidazole with either anaerobic or aerobic incubation.

In a bioassay for metronidazole, a modified agar well diffusion technique was used. Two clostridial species were used as the test organisms, and, with minor variations, the method was as effective with aerobic as with anaerobic incubation. Serum and urine levels of 0.25-128 mug/ml were measurable by this method without dilution of the specimens being assayed. The principal acid and alcohol metabolites of metronidazole were found to possess only approximately 5% and 30%, respectively, of the activity of the parent compound.


T-mycoplasmas: Growth patterns and physical characteristics of some human strains.

Five T-mycoplasmas isolated from patients with nonspecific urethritis and five laboratory strains of T-mycoplasma were examined for differentiating biological properties. The strains differed by the presence or absence of a lag phase and the number of T-mycoplasmas constituting a colony-forming unit (cfu). Most T-mycoplasmas had no lag phase and a cfu consisting of single organisms. All had biphasic ultraviolet inactivation curves typical of suspensions containing both mononucleate and binucleate cells. Binucleate cells probably were in the process of division. They resisted sonication for 3 min. Sonication disrupted multicellular cfu in to single cells within 2 min. Stationary-phase organisms died more rapidly than exponential-phase cells. T-mycoplasmas replicated at 2 C; they grew more slowly in T-broth at 40 C and died in 2.5 min at 56 C. Inactivation curves at 45 C and 50 C differed but insufficiently to permit identification of individual strains. At pressures less than 5 psi, single-cell suspensions passed through filter membranes with 0.65-mum and 0.45-mum pores but were retained by membranes with 0.22-mum pores.


Sequential responses of the renin-angiotensin-aldosterone axis to acute postural change: effect of dietary sodium.

The simultaneous levels of plasma renin activity (PRA), angiotensin II (A II), and aldosterone (PA) were frequently assessed in 13 normal subjects following acute postural change (assumption of upright posture or returning to the supine position) on low (10 mEq.) and high (200 mEq.) sodium (Na+) intakes. The rate of response of aldosterone secretion was also correlated with changes in the metabolic clearance rate (MCR) of aldosterone. Significant increments of PRA and A II on either sodium intake occurred within 5 to 20 minutes; the peak values occurred within 90 minutes and tended to plateau until the end of the study (240 minutes). The mean absolute peak levels were approximately 2 to 3.5-fold greater than control. Increments of PA were initially delayed 20 to 30 minutes, but peak levels also were achieved by 90 minutes. The secretion rate of aldosterone increased 4-fold on the 10 mEq. Na+ and 2-fold on the 200 mEq. Na+ intake even though MCR declined 30 to 40 per cent in the upright posture. Sodium restriction enhanced the rate and magnitude of response of all parameters. Specifically, the slope of the regression relationship between PRA and PA was more than 4-fold steeper in the sodium-restricted than sodium-loaded subjects. From the rate of decline in PRA following resumption of supine posture, the half-life of PRA was estimated to be 14 to 15 minutes. The present study demonstrates that acute changes in posture are associated with closely correlated changes in PRA or A II. To varying degrees, it appeared that sympathetic activity, intravascular volume, diurnal secretion, and the sodium ion play a role in the sequential responses of these parameters to acute postural alterations.


Growth hormone secretion and sulfation factor activity in pseudohypoparathyroidism.

The role of growth hormone and serum sulfation factor in the pathogenesis of the short stature of pseudohypoparathyroidism was investigated in two adults with this syndrome. Growth hormone levels rose to 10.6 and 26.0 ng. per milliliter with insulin hypoglycemia, and reached 6.6 and 6.4 ng. per milliliter 120 minutes after 500 mg. of L-Dopa orally in these patients. Serum from both patients supported the incorporation of 35S-sulfate into chick embryo pelvic rudiments when incubated for 6 hours in a physiologic salt solution containing 13 amino acids. Pseudohypoparathyroid serum also stimulated the incorporation of radioactive sulfate into rat costal and xyphoid cartilage at a level similar to that observed with normal serum. It is concluded that growth hormone and sulfation factor deficiency are not implicated in the short statue of pseudohypoparathyroidism.


Subcellular distribution of nitroblue tetrazolium reductase (NBT-R) in human polymorphonuclear leukocytes (PMN).

Subcellular distribution study of cytoplasmic organelles was performed on human polymorphonuclear leukocytes after homogenization in 0.34 molar sucrose by differential centrifugation and sucrose density gradient centrifugation of the homogenate. The whole homogenate and each fraction was assayed for nitroblue tetrazolium (NBT)-reductase with and without 1 mM potassium cyanide, and the distribution of this enzyme was compared to the distribution of lysozyme, peroxidase, beta-glucuronidase, and acid and alkaline phosphatase. Enzyme recovery was 97 per cent and ranged between 74 and 124 per cent. Latent activity of all enzymes except NBT-reductase, acid, and alkaline phosphatase was demonstrated by observing a four- to sixfold increase in activity after the addition of Triton-X 100. Maximal relative specific activity using either DPNH or without cyanide for NBT-reductase was found in the 100,000 x g differential centrifugation fraction and was concentrated in the less dense top fraction of the sucrose density gradient. The distribution pattern was similar to acid and alkaline phosphatase. In contrast, the maximal concentration of beta-glucuronidase and peroxidase was found in the heavier 7,200 x g granule fraction and in the more dense bottom fractions of the sucrose density gradient. Maximal lysozyme activity was concentrated in the 30,000 x g granule fraction and in the fractions located between the heaviest and lightest fractions of the sucrose density gradient. The lack of latent activity and the similarity of subcellular distribution of NBT-reductase to acid and alkaline phosphatase, two enzymes associated with microsomes and plasmalemal membranes in human polymorphonuclear leukocytes (PMN), indicates that NBT-reductase is also a nonlysosomal enzyme located in microsomes or in plasmalemal membranes. These findings support the previously described histochemical observations that initial reduction of NBT to formazan occurs on the PMN plasmalemal surface membrane at the point of particle attachment. In addition, they suggest that alteration of the surface membrane of the PMN by particle attachment or other surface forces may activate NBT-reductase, leading to an accumulation of formazan in the region of the altered membrane as the phagocytic vacuole is formed.


Thiamine transport across the rat intestine. II. Effect of ethanol.

We have previously investigated the normal characteristics of thiamine intestinal transport in rats and found that a very low concentrations (0.06 to 2.0 muM) thiamine transport is a saturable, carrier-mediated, active process while at high concentrations (greater than 2.0 muM) transport proceeds by simple diffusion. The present studies were undertaken to characterize the effect of ethanol on thiamine transport. Intact isolated loops were used to measure rates of 35S-thiamine hydrochloride absorption into the circulation in vivo, and everted jejunal segments to measure net transmural flux, unidirectional uptake, and cellular exit of 14C-thiamine hydrochloride in vitro. Intragastric administration of ethanol (50 to 750 mg. per 100 grams of weight) reduced absorption of low thiamine concentration in vivo to 65.44 per cent of control value. A similar inhibition was noted after intravenous ethanol. Once attained, the inhibition of thiamine absorption was not related to the ethanol dose or to ethanol concentration in the blood or in the intestinal lumen; this inhibition was reversible. In contrast, ethanol did not affect absorption of high concentrations of thiamine. These findings were confirmed by the in vitro results. In transmural flux studies, the movement of low, but not high, thiamine concentration against a concentration gradient was inhibited by ethanol, so that the normal serosal/mucosal ratio of 1.5 was reduced to 1.0. Ethanol did not affect unidirectional uptake into the mucosa of either low or high thiamine concentrations, but blocked cellular exit of low thiamine concentrations from the cells into the serosal compartment. Exit of high thiamine concentrations was not affected. Ouabain, like ethanol, markedly reduced cellular exit but did not influence uptake of low thiamine concentrations. The present studies suggest that ethanol adversely affects the active, but not the passive, component of thiamine transport. Moreover, ethanol appears to block thiamine exit from the cells but does not affect cellular uptake of thiamine. The similarity to ouabain action suggests that ethanol may impair active thiamine transport by inhibiting Na-K ATPase activity.


The effect of massive liver resection on platelet kinetics in the rat.

The effect of partial hepatectomy on platelet kinetics has been assessed in the rat. Four-fifths hepatectomy resulted in thrombocytopenia reaching 50 per cent of control platelet counts on the fifth postoperative day. Platelets were found to accumulate in the sinusoids of the liver remnant after partial hepatectomy. Once correction was made for changing blood volume, it was found that during the first two postoperative days 50 per cent of platelets had disappeared from the blood. After this, platelet numbers fell slowly for a further three days following which recovery commenced. Neither 51Chromium labeled platelet survival nor total organ pooling of platelets varied from the normal after four-fifths hepatectomy. Although platelets were shown to accumulate in the liver remnant the numbers involved did not contribute significantly to the thrombocytopenia. The mechanism responsible for the thrombocytopenia was suppression of entry of platelets into the peripheral blood. The observed effect was specific for platelets; erythropoiesis was not suppressed. Megakaryocytes showed a decrease in average diameter and ploidy value, a change seen also after physiologic suppression of platelet production; these findings raise the possibility that the liver is concerned in the elaboration of thrombopoietin. However, as four-fifths hepatectomy results in immediate cessation of entry of platelets into the peripheral circulation, a phase of platelet production in which the principal physiologic regulator has hitherto been considered to have no effect, a second mechanism must be invoked affecting the final step of platelet production.


Inhibition of the membrane transport of folates by anions retained in uremia.

Previous studies from this laboratory indicated that inorganic and organic anions inhibit the unidirectional influx and net transport of the folate analog methotrexate in mammalian cells. Studies were undertaken to establish whether anions retained in uremia might inhibit the membrane transport of folates. Methotrexate was utilized as a model folate compound and its transport was determined in the Ehrlich ascites tumor cell. Influx of methotrexate was inhibited when cells were suspended into sera or ultrafiltrates of sera (pH adjusted to 7.4 by regulation of PCO2) from uremic patients, an effect that was decreased after the patient underwent hemodialysis or peritoneal dialysis. The inhibitory effect of uremic sera correlated well with the level of retained anions as estimated from the "anion gap," but could not be related to changes in osmolality, blood urea nitrogen (BUN), sodium, potassium, calcium, or magnesium. While inhibiting the influx of methotrexate, inorganic anions did not displace methotrexate from albumin binding sites. Anionic inhibition of the membrane transport of 5-methyl [14C] tetrahydrofolate was also demonstrated and this was shown to be accompanied by a depression in the rate of incorporation of the labeled 14C moiety into nucleic acids and protein. The data suggested that transport of folates is impaired in uremia and raises the possibility that whatever the measured blood folate level in the uremic individual with retained anions, the rate of uptake of folates into folate-dependent tissues which this blood folate level will sustain may be reduced.


Alteration by immunosuppression of early mortality in a naturally occurring cardiomyopathy.

Turkeys from a highly inbred flock, which shows a 100 per cent incidence of naturally occurring cardiomyopathy, were treated daily for 3 weeks following hatching with cortisone acetate, or for 4 days following hatching with parenteral cyclophosphamide, or underwent surgical removal of the bursa of Fabricius at hatching. Mortality was significantly reduced during the first 10 days of age when each of the treated groups was compared with its own control group. By 5 weeks of age, the mortality rates in the bursectomized and cyclophosphamide-treated birds were not significantly different than their control groups. Five-week mortality in the cortisone acetate-treated group, however, was significantly lower than in its control group. Long-term morbidity, as reflected by the incidence of cardiac dilatation and hypertrophy in all birds during or killed through one year of age, was lower in the cortisone acetate-treated birds and significantly reduced in the bursectomized birds. These data suggest that the humoral immune system may function in the pathogenesis of this naturally occurring cardiomyopathy in the turkey.


Comparison of methodologies for thalassemia screening by Hb A2 quantitation.

An efficient, reliable, inexpensive screening test for beta-thalassemia triat is required before the National Cooley's Anemia Control Act can be carried out. Densitometry of hemoglobin samples separated by cellulose acetate has become a routine procedure to quantitate Hb A2 and thereby indicate beta-thalassemia trait carriers. To determine the utility of densitometry in quantitation of Hb A2, we evaluated three densitometers marketed in the United States. Individuals with genetically proved beta-thalassemia trait and normal Hb AA controls were studied. Two analytic procedures (elution and column chromatography) for Hb A2 quantitation were used as reference methods. Densitometry was shown to be unsatisfactory for detecting beta-thalassemia-trait carriers. We recommend that a unified approach to the detection of anemia, which would include thalassemia trait, be developed in the United States rather than free-standing thalassemia screening centers and clinics.


Method for extraction of glycoprotein hormones from plasma for use in radioimmunoassays.

Concanavalin-A covalently linked to Sepharose was used to extract the glycoproteins from a volume of human plasma about 10 times that volume usually added to conventional radioimmunoassay systems. Using a chorionic gonadoptropin (hCG) radioimmunoassay, hCG inhibition curves generated in the presence of the extracts were nearly identical to those generated by the conventional method; therefore, the sensitivity of the radioimmunoassays for glycoprotein hormones.


Radioimmunoassays for Ig classes G, A, M, D, and E in spinal fluids: normal values of different age groups.

Radioimmunoassay procedures of sufficient sensitivity (IgG, 0.5 mug per 100 mul; IgA, 25.0 ng. per 100 mul; IgM, 10.0 ng. per 100 mul; IgD, 0.5 U. per 100 mul; and IgE, 1.0 U. per 100 mul) were developed detect and quantitate all 5 immunoglobulin classes in the cerebrospinal fluid on small aliquots (1 ml.) of unconcentrated cerebrospinal fluid. All 5 immunoglobulin classes were routinely detected in normal individuals for the first time, the levels varying with different age groups for IgG and A but not for the remaining immunoglobulin classes. Race and sex had no effect. Standardization of techniques and establishment of normal values for different age groups sets the stage for determination of immunoglobulin changes related to central nervous system disease.


On the immunology of head and neck cancer--a prognostic index. Preliminary communication.

A pilot study on the immune response in patients with carcinoma of the head and neck has been made. The clinical behaviour of such neoplasia is reasoned as being partly determined by the immunological response. If prognosis is related to competence of the immune system then this parameter should be assessed. DNCB (di-nitro-chloro-benzene) skin sensitization and serial lymphocyte transformation studies were performed on all patients whose progress was studied for at least two years. On analysing the results of survival, patients could be divided into two groups--DNCB positive and DNCB negative. The negative patients could be further subdivided; those with a lymphocyte stimulation index of over fifteen; and those beneath this level--the former had a much better prognosis than the latter. Also, such cancer patients were shown to have both cellular and serum factors causing depression of lymphocyte transformation. In the light of all findings, a future programme of investigation is proposed.


Sudden deafness following cardio-pulmonary bypass surgery.

A case is presented of sudden deafness following cardio-pulmonary bypass surgery. Microembolism is believed to be the most likely cause as this is common following the use of pump oxygenator systems. There was no response to anticoagulants.


A cochlear implant electrode.

This study has shown that an electrode array can be passed along the hold length of the cochlea if it is inserted through and opening in the scala tympani of the apical turn. The electrode must have the appropriate mechanical properties and some of these were stiffness and extensibility. The electrode and operative approach should be helpful in stimulating the terminal auditory nerve fibres on a place basis, which is desirable if patients with severe sensorineural deafness are to be helped with a cochlear implant.


Experimental autogenous incus transposition.

Incus replacement or transposition was performed in 82 rats. Findings were similar in that a degree of vitality was retained or regained, though more slowly in boiled implants. Gelatin sponge induced fibrosis. Activity rapid at first ceased later. Generally replanted includes seemed stable.


Eustachian tuboplasty.

Until recently a practical method of reconstruction of the osseous Eustachian tube, stenosed by bony or connective tissue, was yet to be evolved. This paper recommends a new surgical procedure illustrating the possibility of reaching the isthmus of the Eustachian tube by way of a combined transcanal and preauricular approach. After initial cadaveric dissections the basic surgical anatomy was worked out in two rhesus monkeys. Subsequently within the duration of one-and-a-half years two cases of osseous Eustachian tube stenosis have been managed successfully with no post-operative complication.


Masked diabetic mastoiditis.

Seven cases of elderly diabetics suffering from ths so-called 'malignant external otitis' are presented. Chandler (1968) and others consider that this disease is localized to the external ear canal. We do not agree and believe that it is due to a masked middle-ear infection extending through the tympano-mastoid cells to the mastoid process, sparing the antrum and bulging into the floor of the external meatus. In time, extension to petrous apex results in petrositis and a fatal end in many cases.


Recurrent laryngeal nerve palsy and endotracheal intubation.

Voice changes developing after endotracheal intubation have been found to be due to a recurrent laryngeal nerve palsy in four patients. In none of these patients was there any obvious cause and this posed the question whether endotracheal intubation itself could result in a paralysis of the nerve. Cadaver dissection has suggested a way in which which paralysis could occur and this and other possible aetiologies are discussed.


Bilateral symmetrical maldevelopment of external and middle-ear cleft with pharyngeal and soft palate defects.

An unusual combination of first and second arch anomlies is presented. This has resulted in absent middle and external ears with gross naso- and oropharyngeal defects. A brief reference is made to the embryology of this region to explain the anatomical and functional defects. Vascular abnormality during the peri-gestational period is suggested as a possible cause and a conservative line of treatment has been followed with good result.


Laryngeal giant cell tumour.

The surgical treatment of an exceedingly rare neoplasm, the laryngeal giant cell tumor, is reported. After removal of the grossly visible part of the growth and reconstruction of the larynx, the lumen of the latter could be preserved by insertion of metal and/or plastic dilator cannulas. Post-operative X-ray treatment has prevented recurrence of the growth throughout the two-year period which has elapsed since the operation.


Nasal glioma.

A case of nasal glioma is presented along with a brief review of the artiology, structure and diagnostic possibilities and published in earlier surveys. Considering the extremely benign nature of this type of tumour, we are of the opinion that the surgical measures may be relatively conservative and that mutilating, or grossly disfiguring, procedures should be avoided.


Mesenchymal derivatives of the neural crest: analysis of chimaeric quail and chick embryos.

Interspecific grafts of neural tube and associated neural crest (NC) have been made between quail and chick embryos. Structural differences of the interphase nucleus in the two species make it possible to identify quail from chick cells in the chimaeras after Feulgen-Rossenbeck's staining and at the electron microscope level. Owing to the stability of the natural quail nuclear maker labelling, migration pattern and developmental fate of the grafted NC cells could be followed in the host embryo. In previous work it has been demonstrated that the visceral skeleton derives entirely from NC mesenchyme and the various levels of the neural axis from which visceral cartilages and bones originate have been established. In the present work, the contribution to the lower jaw and pharynx of NC mesenchymal derivatives other than bones and cartilages has been studied. It is shown that the dermis in the face and ventrolateral side of the neck has a neural origin. The wall of the large arteries deriving from the branchial arches (systemic aorta, pulmonary arteries, branchiocephalic trunks and common carotid arteries) are entirely made up of mesectodermal cells except for the endothelial epithelium which is mesodermal in origin. The presence in the wall of the common carotid arteries of fluoregenic monoamines-containing cells is demonstrated using the formol-induced-fluorescence technique. Like the secretory cells of the carotid body, the fluorescent cells of the carotid artery wall originate from the rhombencephalic NC. Connective tissue of the lower jaw, tongue and ventrolateral part of the neck originate from the neural crest. Mesectoderm participate in the formation of the glands associated with the tongue and pharynx (lingual gland, thymus, thyroid, parathyroids) giving their mesenchymal component. On the other hand, as demonstrated previously by our group, NC cells are the main cellular component of the UB since they give rise to the calcitonin producing cells. The wall of the oesophagus and trachea is of mesodermal origin, but adipose tissue around the trachea and parasympathetic enteric ganglia of the digestive tube derives from NC. NC cells participate in the formation of striated muscles of the branchial arches and differentiate there into connective and muscle cells. It appears from this study that the differentiating capabilities are similar in mesenchymal and mesectodermal cells with the exception of blood vessel endothelia which in our experiments are always of host origin in mesectoderm-derived tissues. The capacity of the NC to give rise to mesen chymal derivatives is restricted to the cephalic neural axis down to the level of the 5th somite in both chick and quail embryos.


The function of the ectodermal apical ridge and distinctive characteristics of adjacent distal mesoderm in the avian wing-bud.

Blocks of mesoderm about 0-1 mm in diameter were isolated from various regions of chick wing-buds of stages 17 through 22 and cultured individually, or sometimes in pairs, in microtest plate wells. Cell deaths had occurred after 10 h of culture in those explants that had come from the region associated with the thickest part of the ectodermal ridge, and after 11-12 h in all other mesoderm. When the adjacent ectodermal ridge was left attached to the mesodermal block there were almost no cell deaths for up to 24 h of culture. When the dorsal ectoderm immediately proximal to the apical ridge was left attached, but no ridge was present, cell deaths occurred just as they did in mesoderm with no ectoderm. When a number (usually six) of complete ridges were suspended in a wire basket at the top of a well,  cell deaths did not occur in a test mesodermal block at the bottom of the well (six of eight cases). These experiments support previous evivence for a special function of the ectodermal apical ridge in limb morphogenesis, and indicate that there is a chemical messenger. The cells that migrated from distal mesodermal explants (the band up to 0-15 mm from the apical ridge) differed sharply in morphology and behavior from those coming from explants from any more proximal region. Within the proximal mesoderm there was a less striking variation alons the antero-posterior axis. These observations reveal that there is present even at early stages a detailed pattern within the mesoderm of the limb-bud. The particularly striking and distinctive characteristics of that mesoderm closest to the apical  ectodermal ridge provide new possibilities for the understanding of the function of the ridge in limb morphogenesis.


Mitochondrial and other ultrastructural changes in the developing Habrobracon embryo.

Cells of the wasp, Habrobracon juglandis, were studied by electron microscopy with the view to comparing ultrastructural changes, especially those found in mitochondria, that occur during the first two-thirds of the 29 h embryonic period. In 1- to 2-h embryos (the earliest studied) mitochondria are distributed principally in the periplasm and typically are arranged in clumps with their long axes parallel to each other. Based on a study of profiles occurring in thin sections, most appear to be elongate with poorly developed cristae, have dense matrices and are longer than those of later stages. At 3-4 h of age, in incipient blastoderm cells, the mitochondria are distributed throughout the cytoplasm with  40% located lateral to the nuclei and 42% concentrated in a subnuclear position. Most (81%) exhibit spherical profiles, with well-developed cristae and less dense matrices than those found at earlier ages. In fully formed blastodermal cells (7-8 h), mitochondria are similar morphologically except that a lower percentage (53%) are spherical; almost half (48%) have migrated to a supra-nuclear location. In early gastrula cells (11-12 h) no significant variations from the blastoderm condition were apparent. Mitochondria in the oldest cells studied (18-19 h) show somewhat greater structural complexity and variability. The number per cell section is drastically reduced compared to earlier ages, but this, at least in part, is related to a reduction in cell size. Changes observed in other cellular constituents are also described. Comparisons are made with similar variations reported in other developing organisms and their possible significance is discussed.


The development of animals homozygous for a mutation causing periodic albinism (ap) in Xenopus laevis.

This paper describes the development of a mutant strain associated with periodic albinism (ap) in the clawed toad Xenopus laevis. The most outstanding feature of this mutation is the instability of the albino state. In the course of the development there is a succession of three periods of pigment expression: (1) complete absence of melanin pigment, (2) appearance of melanin in the pigmented epithelium of the eyes and in small quantities in skin melanophores, (3) disappearance of most pigment granules. Repeated spawnings show that the mutant syndrome is inherited as a recessive trait. Possible ways of analysing pigment cell differentiation with the use of the mutation described are discussed.


Adult deficiencies and duplications of head and thoracic structures resulting from microcautery of blastoderm stage Drosophila embryos.

Drosophila embryos were damaged by microcautery at the cellular blastoderm stage at the sites of presumptive imaginal cells, identified from fate maps. The resulting adults were analyzed for abnormal structures. Cautery of any of the presumptive imaginal regions can lead to defects in the adult cuticle, though the majority of adults which hatch are morphologically normal. The abnormal adults had one or more discs either deleted, incompletely formed, or misarranged. Several of the structures which were incomplete had duplicated regions. The results suggest that, from the time fo their initial formation in the cellular blastoderm, a group of cells determined to be an 'adult' structure possesses a gradient of developmental capacity which is expressed by certain regions duplicating and other cells regenerating. The types of duplications found were similar to those resulting from other experimental treatments of imaginal discs at later stages in development, indicating that the presumptive imaginal disc cells, when they are first established in the cellular blastoderm, have a similar organization to mature imaginal discs.


A role for the eosinophil in acquired resistance to Schistosoma mansoni infection as determined by antieosinophil serum.

Partial immunity to schistosomiasis mansoni has been demonstrated in mice and has recently been transferred passively with serum, but not with cells. In vitro studies using human and rodent materials have demonstrated antibody-dependent cell-mediated damage to immature schistosomes (schistosomula); the cell involved in some of these in vitro systems appears to be the neutrophil and in others the eosinophil is suspected. In the present study the effect of antileukocyte sera on partial immunity to schistosomiasis was tested in vivo using quantitative assay systems for schistosomula in the lungs and adult worms in the portal venous system. Mice infected with 10 cercariae of Schistosoma mansoni 16 and 32 wk before challenge with 500 cercariae showed reductions in the recovery of schistosomula at 4 and 6 days of approximately 40%; adult worm recovery was reduced by 60%. Treatment with antilymphocyte, antimacrophage, or antineutrophil serum had no effect on the numbers of schistosomula recovered from the lungs of immune animals, but in the mice treated with antieosinophil serum the numbers of schistosomula and adult worms recovered increased to the levels seen in normal nonimmune animals. Furthermore, sera collected from the partially immune mice and passively transferred to uninfected mice conferred a marked resistance to infection as measured by recovery of schistosomula; this was also abrogated by treatment with antieosinophil serum. These studies suggest that antibody-dependent cell-mediated immunity to schistosomiasis occurs in vivo, and also establishes a role for the eosinophil in immune systems.


Inhibition of lymphocyte mitogenesis by immobilized antigen-antibody complexes.

Mouse spleen cells, cultured on surfaces coated with antigen-antibody complexes, are inhibited from responding to the B-cell mitogens, lipopolysaccharide, lipid A, Pneumococcal polysaccharide SIII, and poly I:C. The response to the T-cell mitogen, concanavalin A, is also substantially inhibited by immobilized antigen-antibody complexes, but specific inhibition of the response to phytohemagglutinin is minimal. Control experiments showed that immobilized complexes prepared from IgG F(ab')2 fragments and IgA antibodies (both of which fail to bind to Fc receptors when complexed to antigen) did not show significant inhibitory activity when compared with the inhibition observed with complexes prepared from whole IgG. Suspensions of antigen-antibody complexes prepared from the same antigen and intact IgG antibody did not inhibit mitogenesis. None of the mitogens used could be demonstrated to compete with the binding of aggregated immunoglobulin to the B-cell Fc receptor. It appears that the interaction of Fc receptor-bearing lymphocytes and/or macrophages with immobilized complexes prevents lymphocyte activation by mitogens. It is suggested that the mechanism(s) involved may be relevant to antibody feedback control of the humoral immune response.


Selective phagocytic paralysis induced by immobilized immune complexes.

The phagocytic recognition by peritoneal macrophages plated on glass- or plastic-bound immune complexes of bovine plasma albumin (BSA) and anti-BSA was examined. Ingestion but not the attachment of erythrocytes opsonized with an IgG rich antiserum (EA) was markedly inhibited. In contrast, macrophage interactions with complement-coated (EAC) red cells, or ingestion of latex particles, yeast cell walls or glutaraldehyde-treated erythrocytes was not inhibited. Complexes prepared with pepsin-treated anti-BSA IgG were ineffective indicating a requirement for the Fc region. Inhibition of ingestion of EA was not a consequence of macrophage spreading and did not appear to be mediated by solubilized complexes or by cell-derived inhibitors of phagocytosis. Significant restoration of the ability to ingest EA was obtained when macrophages on complex-coated substrates were incubated for 4-8 h in medium enriched with mouse or fetal bovine serum. Restoration was also attained by removing macrophages from complex-coated dishes and replating onto uncoated dishes. The selective inhibition of ingestion of EA may be due to blocking of Fc receptors by the complexes but depletion of receptors by endocytosis of complexes cannot be ruled out. Alternatively, the complexes may have induced selective failure of the interiorization mechanism.


Cellular immune responses to methylcholanthrene-induced fibrosarcoma in BALB/c mice.

Several in vitro parameters of cellular immunity were examined in BALB/c mice with an experimentally induced fibrosarcoma tumor. The results of capillary migration of spleen cells in high tumor cell dose inoculated mice show appearance of cellular immune response in the early stages of the tumor growth. As the tumor progresses, the cellular response declines and rapidly disappears, culminating in stimulation values near the time of the death of these mice. The blastogenic studies also show early cellular recognition of tumor antigen by mouse spleen cells and whole blood (Z24 h). After the 2nd day following tumor injection, no blast transformation is noted. However, the results obtained with a lower inoculating tumor cell dose demonstrate an initial cellular recognition on the 7th day. This response gradually disappears by the 19th day and remains negative up to the time of the death of these mice. This cellular immunity was confirmed by the cytotoxic experiments showing that the primary cells responsible for this cellular reactivity were the immune cells. An interesting finding was the presence of a factor(s) capable of blocking the cytotoxic effect. The nature and mechanism of this blocking factor(s) is now under investigation.


Properdin: binding to C3b and stabilization of the C3b-dependent C3 convertase.

A function of P in the alternative complement pathway is to prolong the first order decay of the hemolytic sites on EAC43B in a dose-dependent manner. As the number of initial convertase sites is not changed, even when activated  properdin (P) increases the t1/2 10-fold or more, P acts to stabilize rather than to uncover additional sites. P binds to EAC43 to generate EAC43P in a reaction that proceeds slightly more rapidly at 15 degrees C than at 0 degrees C, but reaches the same plateau and does not require divalent cations. The presence of P on EAC43P not only stabilizes the convertase subsequently formed on that cell, but, alternatively, permits transfer to convertase sites on other cells with the stability of the recipient intermediate being dependent on the P available for transfer. The capacity of P to bind to C3b and stabilize C3B contrasts with the inhibitory effect of the C3b inactivator on formation of this amplification convertase.


Immunological and physiological characteristics of the rapid immune hemolysis of neuraminidase-treated sheep red cells produced by fresh guinea pig serum.

The rapid hemolysis by fresh guinea pig serum known to occur with neuraminidase-treated sheep red cells has been investigated with respect to the immunological and physiological properties of the lytic process. The following observations were made: (a) The susceptibility to hemolysis is directly proportional to the amounts of neuraminic acid enzymatically released from the cell surface. Complement lysis is mediated through binding of an IgM antibody protein to membranes of neuraminidase-treated cells. (b) Hemolysis is relatively temperature-independent above about 28 degrees C but below which a decrease in the hemolysis rate occurs. Arrhenius activation energies above and below the transition temperature were therefore found to be different. (c) Colloid osmotic swelling of neuraminidase-treated high potassium sheep red cells with a chloride ion concentration ratio near unity suspended in high potassium medium could not be prevented by sucrose. Hence, colloid osmotic swelling before lysis must be due to the entrance of sucrose and water since sucrose was the only external solute not at equilibrium. (d) From the rate of swelling and the apparent flux of sucrose under nonsteady state conditions an experimental permeability coefficient (P) for sucrose of 3-10(-8) cm-s-1 was computed. Comparison with a theoretical P of 4-10(-6) cm-s-1 for sucrose freely permeating through a single, hypothetical membrane lesion per cell of 60 A effective diameter indicates a membrane lesion which permits the passage of solutes larger than cations, but clearly constrains the free diffusion of sucrose.


The role of small changes in the acoustic environment in modifying the startle reflex.

When either the intensity or frequency spectrum of an approximately 70-db. SPL narrow-band noise was abruptly changed by a small amount, the rat's response to a startle stimulus presented 64 msec later was inhibited. When similar small frequency changes preceded the startle stimulus by ony 5 msec, the latency of the startle response was reduced, but even relatively large changes in intensity of the antecedent stimulus had no effect on response latency. These findings provide added support for the generalization that the neural processes associated with startle are engaged by small changes in the auditory environment. They also point to a measure of separation between the processes responsible for inhibition and those responsible for latency shift.


"Pseudoconditioned" jaw movements of the rabbit reflect associations conditioned to contextual background cues.

Two experiments employing 180 rabbits and involving tone conditioned stimuli (CSs) and intraoral water unconditioned stimuli (UCSs) investigated pseudoconditioning of jaw movement. CS-alone, UCS-alone, paired CS-UCS, and four explicitly unpaired CS-UCS treatments were compared to no stimulus presentation. UCS-alone presentations were sufficient to produce pseudo-CR (conditioned response) acquisition. Pseudo-CRs were retained and gradually extinguished over 30 days of CS-alone presentations. Random sequences of unpaired CSc and UCSs produced higher pseudo-CR frequencies than fixed sequences. A pseudo-CR partial reinforcement extinction effect was observed. Background extinction, that is, simply confining the subject in the experimental environment without stimulation, was effective in extinguishing both pseudo-CRs and CRs. Pseudo-CR results could not be attributed to CS-UCS trace conditioning, sensory preconditioning, second-order conditioning, or intra-analyzer conditioning. Results indicate that the associative mechanisms underlying pseudoconditioning phenomena involve conditioning of associations to contextual background (apparatus, trace, temporal, and sequential aftereffect) cues by UCS-alone and unpaired UCS presentations.


Eye movements under different rehearsal strategies.

Eye movements were recorded while subjects studied lists of simultaneously presented words. The 24 subjects in the storage group studied for immediate recall, and the 24 subjects in the coding group studied primarily for a later, final recall. Those subjects in the coding group had longer eye fixations and fewer regressions than did subjects in the storage group. In addition, the subjects in the coding group recalled fewer words in immediate recall and more words in final recall than did the subjects in the storage group. These results were interpreted as supporting the elaboration hypothesis of coding in rehearsal, which states that coding into long-term store consists of rehearsing both old and new information in short-term store. The results did not support the concentration hypothesis, which states that coding into long-term store consists of intensively rehearsing a smaller number of items than rehearsed under a storage strategy. The eye movement data also indicate that subjects read about twice as many words as they overtly rehearse.


Recognition memory as a function of encoding strategy and stimulus codability.

The primary purpose of this research was to determine how imaginal and verbal encoding strategies intereact with various stimulus characteristics to either enhance or retard recognition; the secondary purpose of these studies was to test the conceptual coding hypothesis of Ellis, 1972. A between-groups multivariate factorial analysis of covariance experiment and a within-subjects multivariate factorial analysis of variance experiment were conducted. In Experiment 1 it was found that low-codability shapes were better recognized under the verbal encoding set rather than the imaginal encoding verbal encoding sets; and high-codability shapes were not better recognized than low-codability shapes. However, in Experiment 2, where instructional set was a within-subjects factor, it was found that low-codability shapes were not better recognized under the verbal encoding set than the imaginal encoding set.


Sensory and meaning features in stimulus recognition and associative retrieval.

Three experiments addressed the problem of isolating the effects of sensory similarity on subprocesses involved in coding paired associates. In the first, the standard recognition-recall procedure was used and stimulus similarity, concreteness, and frequency were varied. However, because of concern with the validity of this recognition procedure as a measure of functional stimulus contact, an alternative was developed. This alternative led to the second study in which only stimulus similarity was manipulated. In the third experiment, similarity was varied, and the pairs were either associatively compatible, unrelated, or incompatible. The results using the new procedure indicated that similarity consistently disrupted functional stimulus contact but not associative retrieval. By contrast, associative relatedness facilitated both subprocesses.


A categorically postcategorical interpretation of the modality effect: a reply to Nilsson.

Watkins found the modality effect undiminished when four-syllable rather than one-syllable words were used, and concluded that the effect has a post-categorical origin. Nilsson replicated this result, and also found that with entirely unfamiliar words the effect was greater with one-syllable words than with four-syllable words. Nilsson considered his findings to be in support of a precategorical origin of the effect. This reply argues that, to the contrary, Nilsson's findings are not only consistent with a postcategorical interpretation, but also inconsistent with a precategorical interpretation.


Effects of visual and tactual stimulus presentation on learning two-choice patterned and semirandom sequences.

Three experiments compared the effects of visual and tactual stimulus presentation in two-choice sequential learning situations requiring a predictive response. In Experiments 1 and 2, subjects received a five- or six-unit repeating pattern; in Experiment 3, they received a semirandom sequence. Tactual as compared to visual stimulus presentation resulted in less trials to criterion in predicting a repearing pattern and in earlier frequency matching in predicting a semirandom sequence. These results suggest an unusual tactual adeptness in binary serial learning. Additionally, a new method of analyzing conditional responding in th brobability learning paradigm is described and applied to the data in Experiment 3.


Preselection in short-term motor memory.

Recent studies by Jones (1974) have posited that accurate movements in short-term motor memory (STMM) are mediated by the subject's ability to preset effector mechanisms and monitor their efferent output. Three experiments were conducted to examine this hypothesis. Experiment 1 involved comparisons between the reproduction of the end-location and the reproduction of the distance of a preselected movement. The results revealed that preselected location was superior to preselected distance, indicating that the efference attached to movement extent was not primary. Experiment 2 examined whether location cues were primarily encoded independent of the movement presentation mode. The subjects recalled target locations under preselected, constrained, and passive movement conditions. Recall in the preselected condition was superior to that in the constrained and passive conditions, which showed no difference, suggesting that afferent location information per se was not totally responsible for recall accuracy. Experiment 3 examined the processing requirements of preselected, constrained, and passive location information by filling the retention interval with interpolated processing activity. While preselected location was clearly superior, the three conditions were not differentially affected by processing activity. These overall findings were interpreted as contrary to Jones (1974) and pointed to the importance of preselection in short-term motor memory.


Effect of subvocalization on memory for speech sounds.

Subjects in two groups were presented with sequences of 6 consonant-vowel syllables for ordered recall. Subjects in both groups were trained to suppress subvocalization. Only subjects in the feedback group were asked to suppress subvocalization during the experiment, while subjects in the no-feedback group were allowed to subvocalize during the memory task. Analysis of the electromyographic records showed a large decrease in subvocalization in the feedback condition, and results of the memory task revealed an increase in errors for this group. However, a comparison of errors within each group revealed an identical pattern of overall errors and intrusion errors on subvocalization and nonsubvocalization trials, and these results were identical in both groups. The results suggest that requiring subjects to simultaneously suppress subvocalization and remember syllables depresses performance slightly, but encoding of speech sounds in short-term memory occurs independently of subvocal activity during the memory task.


Extremely long-term persistence of the McCollough effect.

The question has been raised whether an associative mechanism is responsible for the persistence of the McCollough effect. Since current estimates of its rate of decay are derived from procedures in which subjects are repeatedly tested, it was hypothesized that the measured effects might be attenuated by the testing process. Accordingly, a comparison was made between repeated testing and time-elapse testing. A conventional group of 16 subjects had repeated testing at 0, 8, 24, 56, and 120 hr. after induction. Five other groups of 16 were run, each at one of the time delays, with no intervening tests; an additional measure was taken where appropriate at 120 hr. A magenta-green nulling procedure was used to assess the aftereffect. The repeated-test group showed a linear decrease of effect against the stated delays, reaching zero at 120 hr. In contrast, the time-elapse groups showed little decline up to 120 hr. Those groups retested at 120 hr. showed declines due to prior testing. When four more groups were subsequently tested at intervals up to 2,040 hr., the effect remained at better than half strength.


Familiarity affects visual processing of words.

While previous research has demonstrated that words can be processed more rapidly and/or more accurately than random strings of letters, it has not been convincingly demonstrated that the superior processing of words is a visual effect. In the present experiment, the cases of letters were manipulated in letter strings that were to be compared on the basis of physical identity. Mean response time was shorter for words than for nonwords even for pairs of letter strings that differed only in case (e.g., site-site). This finding implies that the advantage of words over nonwords (the familiarity effect) typically observed in the simultaneous matching task is not due solely to comparison of either the word names or the letter names and, thus, that at least part of the familiarity effect must be due to more rapid formation and/or comparison of visual representations of the two letter strings when they are words. Further analysis failed to reveal a significant involvement of phonemic or lexical codes in the comparison judgments.


Judging up and down.

In Experiment I subjects were asked to judge whether an arrow was pointing up or pointing down at various heights inside a surrounding rectangle. They were faster on an arrow pointing up the higher it was in the rectangle, and they were faster on an arrow pointing down the lower it was in the rectangle. Experiments 2, 3, and 4 were designed to test sources for this"congruity effect." The intrusive height information for each arrow was assumed to facilitate or interfere with (a) the activation of the correct motor response; (b) the maintenance of the implicit instruction "Is it pointing up, or is it pointing down?"; or (c) the selection of the criterial perceptual information as a basis for the response. All three experiments were consistent with c, but not with a or b. Indeed, the results contrasted with previous demonstrations of the Stroop effect in certain critical features.


Individual differences in adult foveal visual asymmetries.

The existence and nature of asymmetries in the recognition of elements of a visually presented array have been topics of dispute. In the present study, 32 adults responded to a single vertical or horizontal bar embedded in one circle of a 5 times 7 array of circles by touching a plate corresponding to the orientation of the bar. Two thirds of the subjects were left superior, while one third were right superior. Performance was in general top superior and decreased with increasing distance from the center. Possible explanations for these asymmetries are examined in terms of sequential processing, acuity dominance, hemispheric specialization, and selective attention.


Hemisphere differences in the effects of cuing in visual recognition tasks.

In Experiment 1 uncued recognition of single letters presented in left or right visual fields showed no hemispheric asymmetry, but cuing by alternatives produced a left-hemisphere advantage. Uncued recognition of words was better in the right visual field (left hemisphere), and this advantage was unchanged by cuing by alternatives or cuing by class. In Experiment 2 a mixed series of words, digits, and dots was presented. Uncued trials showed no asymmetry, but when a precue indicated which type or stimulus would appear next, a left-hemisphere advantage for words was evident. Cuing also produced a nonsignificant shift toward a left-hemisphere advantage for digits and a right-hemisphere advantage for dots. The asymmetrical effects of cuing can be explained by Kinsbourne's attentional model of lateralization, which suggests that cuing may selectively activate one hemisphere, and so bias attention toward the contralateral visual field. Repetition effects within and between visual fields were analyzed but no asymmetries were found.


Aging faces as viscal-elastic events: implications for a theory of nonrigid shape perception.

A theory for the perception of events is proposed using the concepts of transformational and structural invariants. This approach involves the application of a method of spatial coordinate transformation to characterize the remodeling of faces by growth. By construing growing faces to the viscal-elastic events, the perception of the relative age level faces in made amenable to the proposed event perception analysis. Shear and strain transformation are compared as alternative formulations of growth-produced changes in the shape of  human profiles. Thes studies indicate that profiles transformed by strain elicit more reliable rank-order age judgments than those transformed by shear, although shear had a small significant effect. It is also shown that subjects are highly sensitive to small changes in strain, and that perceived identity of a shape is preserved under the strain transformation. The explanatory adequacy of the event perception theory of age information is compared to that of more traditional feature analytic theories.


On the relation between time and space in the visual discrimination of velocity.

Is the perception of velocity determined by the prior discrimination of spatial and temporal distances? Two experiments sought to answer this question by comparing the discriminabilities of moving stimuli varied in spatial extent, temporal duration, or in redundant combinations of both variables. The subject's task was to identify which of two alternative stimuli was presented on each trial. A set of four stimuli was constructed from two values of spatial extent and two values of temporal duration. Separate conditions required discrimination of each of the six possible pairs of these stimuli. Experiment 1 examined continuous motion and Experiment 2 examined apparent motion for stimuli with short (50 versus 65 msec) and with long (500 versus 650 msec) interstimulus intervals. With continuous motion and with good apparent motion (short intervals), the discrimination between the different-velocity bivariate pairs was too accurate to be attributed only to discriminations of the spatial and temporal extents of the motion. This did not occur with poor apparent motion. Evidently, time and space are perceptually related.


Perception and extrapolation of velocity and acceleration.

A moving target disappeared behind a screen and subjects predicted when the target passed behind a marker on the screen. When the target moved with constant velocity, predictions were extremely accurate, regardless of the spatial and temporal exposure and concealment of the target and regardless of its rate of velocity. When the target accelerated, accuracy of prediction decreased with increasing acceleration and with increasing target concealment. Analyses of the results suggest that the perception of velocity and acceleration is direct and accurate and that extrapolation of velocity and acceleration incorporates concrete and abstract characteristics of the motion that was seen. It is proposed that the motion perception system is tuned to accelerated rather than to constant velocity movement.


Cardiac activity and information processing: the effects of stimulus significance, and detection and response requirements.

In two experiments, measures of heart rate and electromyographic activity were obtained from 40 male undergraduates while they performed two series of trials involving a sequential information processing task. Each trial consisted of a warning light, three successive tones, and a responded light, separated by 6-sec intervals. In Experiment 1, subjects responded only if the three tones were of different frequencies. Acclerative heart-rate responses to the last tone increased as a function of the significance of that tone. Subsequent cardiac decelerations were only observed if the subject was preparing to make a response. These results were replicated in Experiment 2, in which subjects responded only if two of the preceding tones were of the same frequency. Electromyographic activity was not significantly affected by stimulus significance or response anticipation. The data indicate that cardiac acceleration and deceleration reflect two independent psychological processes, associated with information-processing and decision-making activity on the one hand, and preparatory activity on the other.


Behavioral perspectives in coronary care.

Thirty-eight patients admitted to the Coronary Care Unit were interviewed to discover the natural history of their moods and to assess their level of understanding of their medical condition. A progression of moods from anxiety to denial to depression was noted. Only seven of 38 patients were found to have a good understanding of their illness. Several barriers to doctor-patient communication were identified, including patient's denial, patient's distractibility due to surroundings, patient's "wishfully hearing," doctor's unwarranted assumptions about the patient's understanding, doctor's overuse of medical terminology, and doctor's unawareness of patient's emotional state. Finally, four suggestions for improving total patient care in the Coronary Care Unit are proposed: (1) understand the natural history of patient mood and perceive where your patient is in the progression, (2) institute formal teaching on dealing with patients' moods for nursing and medical personnel, (3) be aware of, and deal with, the barriers to physician-patient communication, and (4) institute formal patient education programs to aid communication and understanding.


Runaways: a growing social and family problem.

The problem of the juvenile runaway is one of increasing magnitude, and it is causing considerable alarm among lay and professional people. As the age of the runaway becomes younger and the harmful consequences of being away from home increase, public attention has focused on the problem. Family physicians are in a unique position to provide both preventive and remedial help to runaways and their families. Some of the ways in which physicians may play a significant role in this serious problem include individual and family counseling to anticipate and prevent such episodes and counseling to strengthen the adolescent-parent relationship following a running away episode.


The management of ordinary grief.

Considerable experience with the problem of ordinary grief has led to the development of some basic management principles which are presented in this paper. The discussion is centered around a case history which originated in a family practice setting. A transcribed interview with the patient emphasizes technique. The working through of grief requires an early and open expression of the pain associated with loss of a loved one. After a discussion of the dynamics of anxiety, grief, and hostility that underlie a grief reaction, specific suggestions for means of helping the bereaved express their feelings and work out their grief are offered.


A computer-administered interview on life events: improving patient-doctor communication.

A computer-administered interview on life events (CAI-LEV) was developed for use by patients in the waiting room of the model family practice unit at the Medical University of South Carolina, Charleston, South Carolina. Computer printouts of CAI-LEV are immediately available for doctor/patient communication, so that CAI-LEV fits into ongoing patient flow and care. Throughout a three-month study, confidentiality of information was protected by the use of numbers for patient responses to questions in 16 areas covering a wide range of possible life events. The adept physician can utilize the printout to assess stress in the patient's current situation, to focus quickly on any particular area of concern, or to initiate a counseling session. Of some 250 completed interview, 93 have been reviewed by residents and faculty after in-depth utilization during patient care. Of these 93 physician-evaluated interviews, 40 percent yielded important new information, while in 22 percent of the cases, doctor/patient communication was improved.


Emergency room use by patients from a family practice. Patterns of illness and motivation.

Patient visits to hospital Emergency Rooms, often for non-urgent illnesses, have increased phenomenally. Yet, an Emergency Room cannot give satisfactory care for those non-urgent illnesses since its management is fragmented and episodic, the antithesis of family practice. This study of private patients from a family practice explores the total spectrum of illness taken to an Emergency Room over a six-month period and the motivation behind the patients' visits. Diagnoses were not distributed at random but fell into discrete patterns of illness of epidemiological interest and which suggest possibilities for prevention. Emergency Room visits were made at times of self-perceived crisis when the private physician was considered inaccessible, and the hospital came to mind as a convenient and reliable source. The family physician should be aware of the special characteristics of his patients who visit Emergency Rooms and alert to the possibility of prevention of traumatic episodes. He should also consider follow-up care on those patients who make Emergency Room visits, with particular reference to exploring those common psycho-social problems which may have loomed large in the motivation for the hospital visit and yet were not recognized or treated at that time.


A critical review of periodic health screening using specific screening criteria. Part 4: selected miscellaneous diseases.

Despite the increasing interest in recent years in prevention and early recognition of asymptomatic disease, an objectively based program for periodic health screening of asymptomatic adults has yet to be proposed for the primary care physician. This is the last in a series of four articles which have critically examined the feasibility of screening procedures for 36 selected diseases. Six basic criteria are adopted as necessary to justify periodic screening. Specific screening recommendations are made for each disease, and a longitudinal screening program for asymptomatic adults is proposed. Cost and patient education are two important factors in any viable screening program.


Limp in childhood.

A method is presented to assist the physician in diagnosing the cause of a limp in a child. This is based on how diseases alter locomotion. The normal gait can be affected in any one of five ways: shortened extremity, contracture, loss of supporting structures, pain, and paralysis. Each of these pathological states produces a characteristic limp which can be observed and recorded by noting the movements of the pelvis and the trunk, and the position of the joints of the lower extremities. Once the examiner has determined how the gait is affected, it becomes less difficult to determine the causative condition, based on the history, physical examination, and ancillary studies which would be ordered.


Simple wounds and simple incisions.

Wound healing without complications and with minimal scarring is facilitated in minor surgical procedures by careful attention to basic surgical principles as reviewed in this article. "Langer's lines" represent the natural creases of the skin and are helpful in locating incisions. Whenever possible, incisions should be made in the skin crease, particularly in the neck or across moving parts. Some incisions, such as those required for drainage of pilonidal or perirectal abscesses, must be carefully located with specific reference to underlying structures.


Characterization of Mycoplasmatales virus-laidlawii 3.

Purified preparations of Mycoplasmatales virus-laidlawii 3 were negatively stained and studied by electron microscopy. They were seen to consist of uniform sized particles having a polyhedral head, 57 nm by 61 nm, and a short tail, 25 nm long, joined to the head at one vertex by a collar. The particles were shown to have buoyant densities of 1-477 g/ml in CsC1, 1-32 g/ml and 1-26 g/ml in potassium tartrate and a sedimentation coefficient, S20,W, OF 290 +/- 13. They are composed of 35-2% double-stranded DNA and five structural polypeptides with approximate mol. wt. of 172000, 81000 73000, 68000 and 43000. The classification of the virus from its morphology and chemical properties is discussed.


Communicative behavior in schizophrenia. The relation of adaptive styles to kinetic and linguistic aspects of interview behavior.

Recent studies of formal kinetic and linguistic aspects of communication suggest that these may be important signposts of internal processes responsible for the regulation and organization of verbal thought. If so, the formal analysis of communication patterns of patients known to have difficulty in cognitive organization (chronic schizophrenics) should reveal kinetic and linguistic characteristics consistent with their level of adaptive cognitive functioning. In the present study, 16 chronic nonparanoid schizophrenic patients were video recorded during a clinical interview, and their kinetic and linguistic behavior was analyzed according to systems developed in our laboratory. Eight of these patients were chronic, isolated patients, classified by means of a scale for measuring proneness to future hospitalization, as extremely "prone" to rehospitalization, and eight were chronic, overtly oppositional patients, classified as "nonprone" to hospitalization. Prone patients are known to exhibit a relatively impoverished form of cognitive functioning, while nonprone patients exhibit more highly differentiated cognitive functioning. The major findings of this study revealed that the isolated prone patients could be distinguished from the nonprone patients, in their communicative behavior, by an increased utilization of the most repetitive and unpatterned stimulation of body parts, as well as the most simple form of linguistic narration of experience. The oppositional nonprone patients more often utilized circumscribed, patterned, and brief kinetic stimulation of body parts, as well as a form of language construction characterized by a complex conditional (i.e., causal, deductive, or purposive) framework for the expression of thought. In addition, social and affective components of the scale measuring hospital proneness were related to our formal kinetic and linguistic scoring categories. An explanation of these findings was offered based upon the well documented relationship observed in the literature between isolation and hyperarousal in chronic schizophrenia. That is, an attempt was made to integrate these findings with the notion that the schizophrenic disorder reflects an integrative deficit which is regulated by increasing the magnitude of proprioceptive feedback (and hence, arousal) through stereotyped repetitive motor activity.


Integration and sealing-over as recovery styles from acute psychosis.

Integration and sealing-over are terms frequently used to describe different types of recovery from acute psychosis. Metapsychological and dynamic propositions regarding integration and sealing-over as recovery styles are presented and illustrated with clinical case material. Particular emphasis is placed on the different modes of conflict resolution characteristic of integration and sealing-over. The ego operations underlying these modes of conflict resolution are discussed.


Daydream patterns and self-awareness in psychiatric patients.

This study investigates the daydream activity of psychiatric patients as measured by the standard retrospective questionnaire vs. a more immediate measure. It also compares the responses of psychiatric patients vs. college students to a daydreaming inventory. Factor analytic and correlative results show considerable consistency between the retrospective and more immediate measures of daydreaming. Psychiatric patients were observed to have less positive and less vivid daydreams than college students, with greater emphasis on fears of failure.


The psychiatric sick role and rejection.

One of the most generally accepted assumptions among mental health professionals is that if the mentally ill were accorded the rights and obligations of the sick role, they would be less rejected by the public. This is the first study that could be found in the literature which examines whether or not this assumption is valid. The data strongly suggest that conferring the sick role on the mentally ill does not lessen rejection, but may, in some instances, increase social rejection. A possible interpretation for this striking and unexpected finding is offered.


Individual differences and setting as determinants of acute adverse reactions to psychoactive drugs.

The relationship between setting and individual differences in determining acute adverse reactions to psychoactive drugs was examined using retrospective data from 483 drug users. Five dimensions of setting were identified. Although there were some small setting main effects, these effects failed to reach significance when shared variance with individual difference variables was considered. For acute adverse reactions to LSD, however, there were seven independent interaction effects between setting and individual difference variables. There were two interaction effects of smaller magnitude related to acute adverse reactions to marijuana. The significance of these results for the current controversy over the relative importance of situational vs. personality determinants of behavior was discussed.


Feedback EEG reactivity and the social responsivity of psychiatric patients.

Social responsivity and spontaneous attentiveness to the environment were evaluated in a heterogeneous sample of psychiatric patients. Each of the 22 male inpatients was first seen in a nondirective, taped interview and then tested with a feedback electroencephalogram (EEG) measure of attention. It was predicted that those patients who were more responsive in the interview a) would initially be more reactive in terms of their EEG response to visual stimulation; and b) would maintain their attentiveness longer than would the less socially responsive group. The results indicated significant correlations (from +.49 to +.64) between the measures of interview responsivity and attentional reactivity for ranks across all Ss. In addition, when the sample was divided into two separate groups of high vs. low social responders, group differences were found with respect to both initial EEG reactivity and the measures of persistence of attentiveness. The results appear to have implications for the "trait" concept within personality theory, and less directly, for aspects of psychoanalytic theory. In addition, the clear group differences obtained on a variety of attentional parameters underline the potential usefulness of the method of feedback in the study of EEG and behavior.


A comment on critical flicker fusion as an objective measure of alcohol tolerance by alcoholics.

A previous paper reported that for alcoholics the threshold for critical flicker fusion is relatively unchanged by the ingestion of alcohol and concluded therefore that the technique could be used to indicate tolerance to alcohol. The present paper urges caution in this respect owing to the evidence that clinical subjects frequently adopt more cautious response strategies than normals with psychophysical procedures. Reports are also reviewed which indicate that alcoholics consume more tobacco than normals and that the stimulant effect of nicotine could antagonize the depressant effect of alcohol on CFF.


Learned helplessness, depression, and anxiety.

The learned helplessness model of depression predicts that depressives should tend to perceive reinforcement as response-independent in skill tasks. Depressed-anxious, nondepressed-anxious, and nondepressed-nonanxious college students estimated their chances for success in a skill or a chance task. (Virtually no depressed-nonanxious subjects could be obtained.) Depressed-anxious subjects showed less expectancy change in skill than nondepressed-anxious subjects, while these two groups exhibited similar expectancy change in chance. Nondepressed-anxious and nondepressed-nonanxious subjects did not differ in either skill or chance. The results for a discrimination learning problem were mixed. The groups did not differ in latency to shut off an aversive noise. So, depressed subjects perceptually distort the outcomes of skilled responding as being response-independent, and they may, under certain conditions, show deficits at learning the consequences of responses. These deficits may reflect learned helplessness and are specific to depression.


Serotonin uptake and release by biochemically characterized nerve endings isolated from rat brain by concomitant flotation and sedimentation centrifugation.

Crude synaptosomal preparations of rat brain were separated by concomitant flotation and sedimentation in a sucrose gradient into fractions containing myelin, nerve endings, and mitochondria, respectively. Two myelin-free nerve ending fractions were obtained which differ in the serotonin content and the activities of the enzymes 5-hydroxytryptophan decarboxylase, monoamine oxidase, choline acetylase, and acetylcholin-esterase. In glucose medium sodium ions stimulate serotonin uptake into the nerve endings while potassium ions in sucrose solution induce the release of this amine.


Acetylcholinesterase neurons in dopamine-containing regions of the brain.

A pharmaco-histochemical regimen was used to examine the morphology and internal organization of acetylcholinesterase (AChE, EC 3.1.1.7) neurons in brain areas--the caudate-putamen nucleus, nucleus accumbens, olfactory tubercule, and subtantia nigra--monoaminergically characterized in terms of their dopamine content. Intense, homogenous staining is produced in these neural regions by other histochemical protocols for AChE; individual AChE-containing neurons cannot be observed reliably or consistently. With the present technique, based on the differential regeneration of AChE in the separate subcellular compartments of the neuron (i.e., axon, dendrite, soma) after intramuscular injection of bis-(1-methylethyl)-phosphorofluoridate (di-isopropylfluorophosphate: DFP), it was shown that AChE was associated with neurons whose cell bodies lay within the brain areas studied. Although the significance of dopaminergic-cholinergic relationships in the caudate-putamen complex, nucleus accumbens, and olfactory tubercule could not be established on the basis of these new histochemical data, arguments were presented indicating that dopamine neurons in the zona compacta of the substantia nigra also contained AChE.


Further studies on the binding properties of cobra neurotoxin to cholinergic receptors in mouse skeletal muscle.

Preparations of 3H-monoacetylated derivatives of Naja naja siamensis neurotoxin siamensis 3 were found to be resistant to degradation and deacetylation during in vitro muscle incubation. A low rate of free 3H-acetate (less than 0.4%) was present in the preparations, but should not interfere with the binding of toxin to cholinergic receptors in mouse extensor digitorum longus muscles in vitro. The binding of toxin to cholinergic receptors in mouse extensor digitorum longus muscle was essentially irreversible. d-Tubocurarine antagonized the binding of toxin in both innervated and denervated muscles. Administration of actinomycin D one day after denervation prevented the appearance of new toxin binding sites in the muscles.


Responsibility of extrastriatal areas for the appearance of psychotic symptoms (clinical and biochemical human post-mortem findings).

1. A Dopa-medication leads sometimes in Parkinsonian patients to a psychosis. 2. The diminished capacity of striatal dopaminergic neurons to store DA leads to a storage of DA in serotoninergic or noradrenergic neurons. 3. Extrastriatal noradrenergic and/or serotoninergic neurons are involved. 4. Dopaminergic receptors of the striatium are not involved because of a lack of kinetic response after L-Dopa application in Parkinsonian patients with akinetic crises. 5. Extrastriatal dopaminergic receptors of DA as "false transmitter" at serotoninergic receptors seem to be responsible for the production of psychotic symptoms, whereas noradrenaline is not responsible. Psychotic symptoms can be imagined to be triggered by a contact of a transmitter to a nonspecific receptor.


Biochemical post-mortem findings in depressed patients.

Biochemical human post-mortem studies on depressed patients indicate an unspecific deficiency of neurotransmitters in several brain areas. The loss of drive of these patients could be correlated with a decrease of striatal dopamine concentration. Noradrenaline was significantly diminished in red nucleus, a fact which points to the characteristic posture of depressed patients. Serotonin was diminished in all brain areas. During remission all values trended to be normal. There also exists a circadian disrhythm in depressed patients resulting in lowered VMA- and HVA-levels in urines during the morning and a remission to normal values in the evening. This agrees with the findings of lowered blood tyrosine levels in the morning. The ratio of blood tyrosine and tryptophan is disturbed during depression and recovers during remission. Central and peripheral biochemical mechanisms seems to be involved in depression syndrom.


Monoaminergic neurotoxins: are they selective?

Introduction of 6-hydroxydopamine into the cerebrospinal fluid produces a selective destruction of adrenergic pathways. However, the selectivity of interstitial injections of 6-hydroxydopamine for catecholamine elements is critically dependent upon the dose and volume of injection must be evaluated by biochemical and cytochemical indices.


Degenerative processes after punctate intracerebral administration of 6-hydroxydopamine.

Various doses of the neurotoxin 6-hydroxydopamine (6-OHDA) were infused into the substantia nigra-ventromedial tegmental area, caudateputamen nucleus, and red nucleus. A maximum of four successively occurring zones of neuropathology could by detected at all injection sites: (1) A zone of complete absence of neural, glial, and vascular elements due to tissue displacement by the cannula, (2) an area of glial cells, developing over time, which surrounded the cannula tract, (3) a region exhibiting virtually complete loss of neuronal elements, and (4) a zone of selective neuropathological reaction or cellular loss in which some neurons were affected and others were not. All investigators who have histochemically and/or histologically evaluated the effects of intracerebrally administered 6-OHDA agree on the existence and genesis, some non-selective process, of the first three zones. Although some scientists maintain that the fourth zone is where 6-OHDA operates selectively, data are presented in this report that other, well-established processes can account for neuropathology beyond zone 3. Prominent among these are retrograde and anterograde degeneration, ischemia as a function of interruption of blood supply, and nonselective traumatization. In addition, the topography of the injected site (e.g., morphology of affected neurons, degree of myelination) was found to be as important a determinant of the locus of tissue damage as the presumed selectivity of 6-OHDA's action. Furthermore, monoamine oxidase inhibition by nialamide did not appear to increase the neurotoxicity of 6-OHDA. Similarly, 1-(2,5-dihydroxy-4-methylphenyl)-2-aminopropane was not a more potent cytotoxin than 6-OHDA even though this new neurotoxin has a propane side chain which renders it immune to monoamine oxidase. These observations, taken together, suggest that considerable cautioon should be exercised in interpreting data from experiments in which 6-OHDA, or related neurotoxins, are used to uncover catecholaminergic mechanisms of behavior and other functional processes.


Histopathologic changes associated with intracerebral injections of 6-hydroxydopamine (6-OHDA) and peroxide (H2O2) in the cat and the rat.

Several factors must be taken into consideration in order to establish whether or not 6-hydroxydopamine (6-OHDA) introduced in the CNS more or less selectively destroys monoaminergic and, more especially, catecholaminergic structures. These include an assessment of all elements possibly damaged following different sites of injection in various species, a comparison with the effects of known neurotoxic agents, the degree of diffusion and/or of dilution of the substance used, the assessment of associated behavioral, neurochemical and morphological changes in the light of the known topography of brain nervous structures etc. A comparison of the effects of 6-OHDA and of peroxide (H2O2) introduced in the CNS suggests  that both agents produced similar morphological changes in various sites of the brains of cats and rats. In the light of various data in the literature and of the results reported in this study it appears that 6-OHDA which may be used to induce a focal lesion cannot be regarded as a specific neurotoxic agent.


Partial selectivity of 6-OHDA induced neuronal degeneration after intraissular injection in the brain with special reference to the nigro-striatal dopamine system.

The selectivity of 6-OHDA induced neuronal degeneration after intra-tissular injection in the brain is discussed considering the morphological and biochemical events occurring in the substantia nigra and in the striatum--after intranigral or intrastriatal application of the drug. The data suggest that a critical intratissular concentration of 6-OHDA is required to induce an elective neuronal degeneration. The importance of the non-specific damage can not be neglected when high doses of the drug are administered in the brain tissue.


Effects of low doses of catecholamine receptor agonists on exploration in mice.

Female mice were given 0.025--0.8 mg/kg of the dopamine and noradrenaline receptor agonists apomorphine and clonidine, respectively, and the effect on explorative behaviour of these drugs was tested in a Y-shaped runway for three minutes. Saline-treated controls displayed a stable exploratory behaviour, declining during the time period measured. The decline probably reflects adaptation to the new environment. Apomorphine depressed the activity, but the configuration of the time curve was the same as in controls. Clonidine also depressed the exploratory activity and further appeared to break the pattern of adaptation, the activity in clonidine-treated mice being low from the beginning. The higher doses of the drugs, alone or in combination, caused a pronounced suppression of the exploration. These mice were observed for ten minutes, under which period their exploration of the runway was not increased, as compared with the first three minutes. The smaller doses used are not known to cause functionally measureable activation of postsynaptic catecholamine receptors. On the other hand these doses are known as cause inhibition of firing in the respective presynaptic neurons and also inhibition of synthesis of the respective transmitter. Thus the present findings are interpreted to be due to presynaptic inhibition of the respective neurons. Clonidine caused a more pronounced inhibition of the exploration than apomorphine, suggesting nordrenaline to be of particular importance for exploratory behaviour.


Effects of melatonin treatment and environmental lighting on the ultrastructural appearence, melatonin synthesis, norepinephrine turnover and microtubule protein content of the rat pineal gland.

Melatonin administration or exposure of rats to darkness for two weeks induced comparable changes in pineal ultrastructure, compatible with a generalized organ's activation. These include an increased number of ribosomes, procentrioles and microtubules, prominent nucleoli and Golgi apparatus, and annulate lamellae. Melatonin treatment resulted in a dose-dependent increase of hydroxyindole-O-methyl transferase and serotonin-N-acetyltransferase activities. In addition it increased by 85% the colchicine binding capacity of pineal homogenates, an estimation of the microtubule protein content of the gland. Pineal norepinephrine turnover was not affected by melatonin treatment. These data indicate that the pineal itself is a target organ for exogenously administered melatonin. Key words: Pineal gland, melatonin, norepinephrine, tubulin.


On the organization of memeory in the optomotor system of the crab Pachygrapsus crassipes.

Memory responses of the optomotor system to rotations of various stripe patterns were studied. The separate elements of the visual background are individually remembered in terms of the parts of the eye on which their images fell. A visual illusion resulting from this property is described. All parts of the retina have an equal capacity to contribute to memory. The memory response results from the summation of contributions from individual elements rather than the maintenance of a fixation upon any particular feature of the situation. Both the separation between background elements for angles from 6 degrees up to 60 degrees and the number of elements present affect the size of the memory evoked response.


Dorsal root recording relevant for mating reflexes in female rats: identification of receptive fields and effects of peripheral denervation.

Cutaneous receptive fields of dorsal roots T11 through S3 in rats were mapped by recording dorsal root multiple unit activity. The receptive fields, having the shape of transverse bands on the skin, are arranged in order according to their dorsal roots, and there are extensive overlaps between adjacent fields. Routes followed by peripheral sensory innervation of skin were also studied by observing effects of various methods of skin denervation on dorsal root responses to cutaneous stimulation. The results are discussed with respect to the somatosensory control of female rat mating reflexes.


Oculomotor areas in the rabbits midbrain and pretectum.

The role of some meso- and diencephalic structures in eye movements was investigated by ablation and stimulation experiments. Optokinetic nystagmus was abolished by small lesions in the lateral pretectum, but not by complete removal of the superior colliculi. Stimulation of the superior colliculus and other visual centers was effective in eliciting nystagmus (slow phase ipsilateral), but the most efficient trigger zones are found in the lateral pretectum and the midbrain tegmentum. Only from these areas could nystagmus still be elicited after degeneration of the primary optic fibers. The lateral pretectal trigger zone is probably identical with the nucleus of the optic tract. It is postulated that this nucleus is an essential station for horizontal optokinetic reactions. Saccades were obtained by stimulation of the mesencephalic central grey, but not for any visual centers such as the superior colliculus.


Gel filtration of myelin using 2,2,2-trichloroethanol as the solvent.

The use of 2,2,2-trichloroethanol as a solvent for myelin from both the central and peripheral nervous systems is described. Concentrated, optically clear solutions of lyophilized myelin in this solvent are stable for weeks. The preparation of highly concentrated myelin proteins by gel filtration in trichloroethanol is described.


Functional characterization of types of plasma membranes in cerebral cortex.

The cerebral cortex of normal oxygenated and of asphyxiated mice has been studied by freeze-fracturing technique with a twofold purpose. First, to investigate changes, if any, in the molecular organization of the plasma membrane of any specific cell type(s) that could be correlated with permeability changes thought to take place as a consequence of asphyxiation. Secondly, to attempt characterization of plasma membranes on the basis of the organization of their fractured faces. The decrease in the extracellular material in asphyxiated cerebral cortex seen in electron micrographs of thin sections could not be correlated with change(s), if any, in the molecular organization of the plasma membrane of any particular cell type. Plasma membranes of various types could be characterized on the basis of the arrangement of particles on the fractured faces. Some of these types correspond to identifiable cell processes, while others have not yet been identified with certainty. Fusion of synaptic vesicles with the presynaptic membrane is mediated through clustering of 100-150 A membrane-associated particles.


Electrolyte- and fluid-spaces of rat brain in situ after infusion with dinitrophenol.

Chemical distribution measurements of radioactive sodium-thiosulfate (35S) and of the brain water indicate that infusion of 2.4-dinitrophenol into  a carotid artery of rats caused a water uptake and fluid shifts from the extra- into the intracellular compartments in the central nervous system. The extracellular marker compound was administered to the brain via ventriculo-cisternal perfusion and intravenous injection yielding almost equal concentrations in plasma-water and perfusate. In order to prevent an active efflux of the label from the tissue, high concentrations were utilized in the perfusate to saturate potential outward transport mechanisms. The indicator space (based on total brain water) was 16% in controls and 12% in experimental animals when marker equilibrium had been attained, which is equivalent in reduction of the extracellular space of about 1/4. Intracellular water and Na+ rose after DNP, while K+ remained all but unchanged. The fluid shift into the intracellular compartment was found to relate closely with a cellular uptake of Na+. The Na+ concentration both in plasma and in the perfusion fluid leaving the ventricular system was consistently reduced in experimental animals. The K+ concentration was significantly elevated in the plasma of experimental animals but virtually unchanged in the cisternal effluate.


Habituation of mechanoreceptive interneurons in the crayfish.

The effect of repetition of sensory stimuli was studied on the responses of mechanoreceptive interneurons in the optic tract of the crayfish (Procambarus bouvieri (Ortmann)). The number of spikes recorded from a given unit gradually decreased during a train of stimuli. The decrease showed a negative exponential time course, with a curvature dependent upon the frequency of stimulation, the intensity of stimuli, and the hour of the day. Habituation is selective for the intensity and rate of stimulation, and the particular spot of receptive field stimulated. Locomotor excitation results in a dimminution of the rate of decay. The effect of a single train of stimuli when leading to pronounced habituation may persist for periods longer than 24 hr.


Viability of some metabolic processes in the isolated toad brain adapted to two osmotic environments.

The viability of the isolated toad brain in an aerated Ringer-like medium has been evaluated by the following criteria: 1) amino acid content before and after incubation; 2) accumulation of amino acids in the incubation medium; 3) a comparison of glucose utilization and [U-14C]glucose metabolism with that occurring in vivo; 4) tissue swelling; and 5) tissue lactate contents. On the basis of these criteria, the isolated toad brain, from toads adapted to a fresh-water or a salt-water environment, retains considerable metabolic integrity for at least 2 hr of incubation at 25 degrees C. Specifically, there was no swelling of the tissue, no apparent accumulation of lactate in the tissue, glucose appeared to be utilized at a rate not too different from that calculated for the toad brain in vivo, and the distribution of label from [U-14C]glucose had an overall pattern which resembled that observed in vivo. The tissue levels of amino acids were generally stable in vitro; however, there was a marked decline in the content of aspartate. The accumulation of amino acids in the medium varied considerably from one amino acid to another. Thus, there was very little net efflux of aspartate, GABA, and glutamate from the tissue but considerable net efflux of glutamine. This efflux of amino acids was greater from brains of hyperosmotically adapted toads than from the brains of toads adapted to fresh water by amounts proportional to their initial tissue contents.


Differences in some properties of newborn and adult brain glutamate decarboxylase.

Some properties of glutamate decarboxylase (EC 4.1.1.15) activity in brain of newborn and adult mouse were studied comparatively. It was found that glutamate decarboxylase of the newborn brain was strongly inactivated by homogenization in hypotonic medium, centrifugation of isotonic sucrose homogenates, preincubation at 37 degrees C or the addition of Triton-X-100, whereas the adult brain enzyme was practically unaffected by any of these conditions. It was also found that the newborn glutamate decarboxylase was less activated by pyridoxal 5'-phosphate and less inhibited by pyridoxal 5'-phosphate oxime-O-acetic acid, than the adult enzyme. These differences do not exist for brain dihydroxyphenylalanine decarboxylase (EC 4.1.1.26) and are not due to the release of inhibitors from the newborn brain. On the basis of the results obtained it is postulated that two forms of glutamate decarboxylase exist in brain: a newborn form, which is unstable and has high affinity for pyridoxal 5'-phosphate, and an adult form, which is much more stable and has low affinity for pyridoxal 5'-phosphate. The possible implications of these findings in the establishment of the gamma-aminobutyric acid dependent synaptic inhibitory mechanisms during development are discussed.