Biomedical subjects
Publications and source records attributed to J Stewart.
Lectin-like receptors capable of binding the bacterium Staphylococcus albus have been demonstrated in the membranes of phagocytes including macrophages, neutrophils and eosinophils from various sources and species. Such receptors are likely to contribute to bacterial adherence and phagocytosis in the non-immune animal.
Effects of enkephalins on hippocampal pyramidal cell activity were studied in situ and in the in vitro hippocampal slice. Active enkephalin derivatives produced a dose-dependent naloxone-reversible excitation in both preparations whereas inactive enkephalin derivatives had no effect. Several different types of experiments, carried out in the slice, strongly suggest that this excitation is due to blockade of inhibitory pathways. First, when the pyramidal cell population spike is increased during enkephalin administration, no change is seen in the simultaneously recorded EPSP. Second, the magnitude of the enkephalin effect is highly correlated with the amount of inhibition, as judged by paired-pulse stimulation, initially present in the slice. Third, if inhibitory pathways are depressed by a brief period of hypoxia, enkephalin has little effect. Finally, enkephalin responses are mimicked by picrotoxin, which selectively antagonizes inhibitory input to the pyramidal neuron. Since enkephalins do not block the effects of GABA, the putative inhibitory transmitter, these data suggest that opioid peptides depress the inhibitory interneurons and disinhibit the pyramidal cells.
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The optimal treatment of pulmonary aspergillomas is not established. Surgical resection is often impossible because of severe, underlying pulmonary impairment, and medical treatment has given negative or inconclusive results. Six patients with symptomatic pulmonary aspergillomas were treated with percutaneous instillation of intracavitary amphotericin B. Four patients who received the full course of therapy showed improvement and stabilization or reversal of progressive roentgenographic changes. Also, follow-up serologic studies of Aspergillus spp. precipitins were obtained in three and were negative. One patient did not tolerate this treatment because of repeated systemic reactions. Another patient did not respond clinically or roentgenographically. Intracavitary amphotericin B therapy should be considered in patients with symptomatic pulmonary aspergilloma, particularly when surgical resection is not feasible.
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Previous reports have suggested that bilingual Native Americans differentiate cognitively in processing their sociologically dominant and non-dominant language. Specifically, there is some evidence that receptive speech functions may be lateralized to the right cerebral hemisphere. To test the notion that this differential specialization may be due to socio-cultural influences, receptive and expressive speech lateralization was examined in a population of acculturated bilingual Native Americans. An analysis of dichotic listening and time-sharing asymmetries indicated that despite evidence for an initial appositional tendency, the Native American subjects were lateralized to the left cerebral hemisphere for both receptive and expressive speech. It is proposed that shifts in the attended perceptual field occur as Native Americans mature perhaps due to an increasing familiarity with a second culture and more propositionally oriented language.
The genetics of human behavior, whether dealing with socio-biology, or with the heritability of schizophrenia or of IQ levels, is currently a controversial domain. The author briefly presents the relatively new methods of genetic pedigree examination utilizing likelihood calculation analyses, and compares this method to the more classical evaluations by family, twin, and adopted children studies. Illustrative examples are drawn from work on the genetics of schizophrenia.
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Methods are described for the systematic construction of genetic models of schizophrenia with one, two, and four loci. All models are constrained to fit the following three parameters: (1) frequency of schizophrenia in the general population = 0.9%; (2) frequency of schizophrenia in the sibs of schizophrenics = 8%; and (3) frequency of "schizophrenic spectrum" in the sibs of schizophrenics = 15%. In addition, a fourth parameter, the frequency of the allele predisposing to schizophrenia, is freely variable. The problems of correcting for ascertainment bias, and of comparing and testing these genetic models, are discussed.
Simulated pedigrees of schizophrenia generally show a clear peak in their likelihood surface corresponding to analysis by the genetic models, which served as the basis for the simulation. The likelihood surface obtained with real data permits determination of the allelic frequency and the selection of an optimal one-locus, two-locus, and four-locus model. These three models have certain features in common, notably, a relatively high frequency of the allele predisposing to schizophrenia (about 20%) and a relatively low index of genetic determination (23%--34%). However, direct likelihood comparisons do not permit distinctions between the one-locus, two-locus, and four-locus models. The most likely interpretation of this finding is that the etiology of schizophrenia is heterogeneous or even nongenetic. However, a simple model with a single completely recessive locus and incomplete penetrance in the homozygote also produces a flat likelihood surface closely resembling that obtained with the real data. With reservation, this single-locus model may be put forward as a potentially useful working hypothesis.
Histamine, at high concentrations, enhanced the uptake of isotopic histidine by guinea-pig basophils. The effect was partially reversed by H1-, but not H2-, histamine receptor antagonists. These data suggest that histamine has a bioregulatory role in its own synthesis.
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A recent case of primary osteosarcoma of the kidney prompted a review of the literature for this rare malignancy. Six cases have been recorded, and this case represents the seventh. The clinical and pathologic features of this lethal tumor are discussed. The presentation of flank pain, gross hematuria, a palpable mass, and a localized parenchymal calcification on x-ray film should alert the clinician to the possibility of renal osteosarcoma.
An interface pressure measuring device for the assessment of subject-cushion interface pressures at ten points has been described. Preliminary trials using 12 healthy subjects on four cushions and three spinal injury patients on six cushings, has been carried out. It was also found that the water and foam cushion distributed the pressure over a large area than the foam cushions.
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The likelihoods of observing 25 four-generational families of schizophrenics comprising 1,333 individuals have been calculated on the basis of 12 different genetic models and one control 'sporadic' model. The control model gave a log10 likelihood (L), of -240.92. Five of the genetic models were definitely excluded as incompatible with certain pedigrees. The three models with the highest likelihoods were: one locus, the heterozygote having a 10% probability of being classified schizophrenic (L: -220.05); two interacting loci (L:-219.46); and four polygenes (L:-216.87).