Biomedical subjects
J Schweitzer
Publications and source records attributed to J Schweitzer.
Summary of the workshop on Drug Development, Biological Diversity, and Economic Growth.
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An analysis of cerebral blood flow in acute closed-head injury using technetium-99m-HMPAO SPECT and computed tomography.
Technetium-99m-hexamethylpropyleneamine (HMPAO) SPECT and x-ray CT were compared in 15 patients with acute closed-head injury. There were 44 focal lesions in all. Fifteen (34%) lesions were seen on both x-ray and SPECT. Seventeen (39%) lesions were seen only on SPECT. Twelve (27%) of the lesions were seen on x-ray tomography only. Of the lesions seen on x-ray tomography but not on SPECT, two were subarachnoid hemorrhage, two were thin subdural hematomas, and eight were contusions. This study shows that SPECT can detect focal disturbances of cerebral blood flow that are not seen on x-ray tomography. It also suggests that there are two types of contusions: those with a decreased cerebral blood flow (i.e., detectable on SPECT) and those with a cerebral blood flow equal to that of the surrounding brain.
Measures of central tendency, variability, and relative standing in nonnormal distributions: alternatives to the mean and standard score.
There are two major disadvantages to reporting test results in standardized scores such as z-scores or t-scores when describing individuals with disabilities. (1) Raw scores on many tasks from disabled individuals are notoriously nonnormal. They are asymmetric, in that they are skewed toward poor scores. (2) Low z-scores give a false impression of dysfunction because able-bodied subjects are often grossly overqualified for the application in question; they may have levels of strength or quickness several orders of magnitude greater than what is needed to do the assessment task. A recommended alternative is to describe the performance of disabled individuals using nonparametric statistics, and to report scores in boxplots, showing the extremes, the median, and the quartiles. Such points are easy to calculate and to interpret, and they are robust against outliers.
Clinical and treatment effects on 3H-clonidine and 3H-imipramine binding in elderly depressed patients.
3H-clonidine and 3H-imipramine binding were measured in depressed patients, 55 years and older. There was no significant difference in either 3H-clonidine or 3H-imipramine binding between depressed patients and age- and sex-matched controls. There was no significant correlation between 3H-clonidine or 3H-imipramine binding and severity of depression before treatment. There was a significant negative correlation between the KD of 3H-imipramine binding sites and Hamilton score over seven weeks of antidepressant treatment. There was no significant difference between receptor data of responders and nonresponders to antidepressant treatment.
Lack of effect of carbidopa on plasma homovanillic acid in normal subjects.
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Functional organization of the electroreceptive midbrain in an elasmobranch (Platyrhinoidis triseriata). A single-unit study.
The response properties of 322 single units in the electroreceptive midbrain (lateral mesencephalic nucleus, LMN) of the thornback ray, Platyrhinoidis triseriata, were studied using uniform and local electric fields. Tactile, visual, or auditory stimuli were also presented to test for multimodality. Most LMN electrosensory units (81%) are silent in the absence of stimulation. Those with spontaneous activity fired irregularly at 0.5 to 5 impulses/s, the lower values being more common. Two units had firing rates greater than 10/s. Midbrain electrosensory units are largely phasic, responding with one or a few spikes per stimulus onset or offset or both, but the adaptation characteristics of some neurons are complex. The same neuron can exhibit phasic or phasic-tonic responses, depending upon orientation of the electric field. Tonic units without any initial phasic over-shoot were not recorded. Even the phasic-tonic units adapt to a step stimulus within several seconds. Unit thresholds are generally lower than 0.3 microV/cm, the weakest stimulus delivered, although thresholds as high as 5 microV/cm were recorded, Neuronal responses reach a maximum, with few exceptions, at 100 microV/cm and decrease rapidly at higher intensities. LMN neurons are highly sensitive to stimulus repetition rates: most responded to frequencies of 5 pulses/s or less; none responded to rates greater than 10/s. Three distinct response patterns are recognized. Best frequencies in response to sinusoidal stimuli range from 0.2 Hz (the lowest frequency delivered) to 4 Hz. Responses decrease rapidly at 8 Hz or greater, and no units responded to frequencies greater than 32 Hz. Most LMN neurons have small, well defined excitatory electroreceptive fields (RFs) exhibiting no surround inhibition, at least as detectable by methods employed here. Seventy-eight percent of units recorded had RFs restricted to the ventral surface: of these, 98% were contralateral. The remaining 22% of units had disjunct dorsal and ventral receptive fields. Electrosensory RFs on the ventral surface are somatotopically organized. Anterior, middle, and posterior body surfaces are mapped at the rostral, middle, and caudal levels, respectively, of the contralateral LMN. The lateral, middle, and medial body are mapped at medial, middle, and lateral levels of the nucleus. Moreover, the RFs of all units isolated in a given dorsoventral electrode track are nearly superimposable. About 40% of LMN, measured from the dorsal surface, is devoted to input from ventral electroreceptors located in a small region rostral and lateral to the mouth.(ABSTRACT TRUNCATED AT 400 WORDS)
Failure to thrive presenting with an unusual skin rash.
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[Family therapy with divorce families: a review].
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Surface markers and size of lymphocytes in human umbilical cord blood stimulated into deoxyribonucleic acid synthesis by Epstein-Barr Virus.
We characterized subpopulations of lymphocytes in human umbilical cord blood which are stimulated into deoxyribonucleic acid synthesis by Epstein-Barr virus. Lymphocytes were examined simultaneously for deoxyribonucleic acid synthesis by autoradiography and for surface markers by rosette formation with sheep erythrocytes or erythrocytes coated with antibody and mouse complement (EAC). The subpopulation which incorporated [3H]thymidine after exposure to virus consisted mainly of cells which formed rosettes with EAC. Lymphocytes were enriched or depleted of thymus-derived lymphocytes (T cells), null cells, or cells forming rosettes with EAC. The extent of sensitivity of the cells to stimulation by Epstein-Barr virus correlated with the proportion of the population which formed rosettes with EAC. When mononuclear cell populations were depleted of T lymphocytes and then fractionated by size, small lymphocytes showed higher rates of deoxyribonucleic acid synthesis after virus exposure and higher transformation frequency than did larger cells or unfractionated cells. Thus, the cells which are stimulated into deoxyribonucleic acid synthesis by Epstein-Barr virus appear to be the same as cells which are ultimately transformed.
[Effect of high-dosage prednisolone administration on interstitial transplantation edema following allogeneic kidney transplantation in rats].
To measure subcapsular pressure of rat kidneys and kidney allografts, microcatheters were implanted in the subcapsular space and the pressure was continuously recorded with a transducer. Subcapsular pressure was found to increase significantly during allograft rejection. After single bolus injection of prednisolone 300 mg/kg on the day of transplantation or on the fourth postoperative day, considerably lower subcapsular pressures were recorded. This steroid effect together with other immunosuppressive measures could have an important influence on graft function and prognosis.
Narcotics and the hypothalamic-pituitary-gonadal axix: acute effects on luteinizing hormone, testosterone and androgen-dependent systems.
The effects of narcotics on several aspects of the hypothalamic-pituitary-gonadal axis were examined in the male rat. Our results indicate that a large number of narcotics acutely depress serum luteinizing hormone levels and that these reduced gonadotropin levels lead to a subsequent fall (1-2 hours later) in serum testosterone levels. The luteinizing hormone-depleting effect of the narcotics appears to represent a specific narcotic action since the (-)-isomers of the narcotics were much more effective than the ()-isomers, naloxone antagonized their effects and tolerance rapidly developed. Further, our studies indicate that the impairment of the functional and structural integrity of the secondary sex organs produced by chronic narcotic administration is not due to a direct effect of these drugs since they have no effect on the uptake of subcellular distribution of testosterone in the secondary sex organs or on the androgen-dependent accumulation of myo-inositol. Consequently, it appears that the testosterone depletion produced by the narcotics is solely responsible for their adverse effect on the secondary sex organs. The results of these studies suggest that the effects of the narcotics on the hypothalamic-pituitary-gonadal axis are confined to either the hypthalamus or the pituitary gland.
[Systemic concepts in residential placement: considerations for pedagogics, counseling and organization].
The paper starts from an analysis of typical problems in residential child care, which can be identified on different system levels (family, family and residential child care unit, family and larger systems, child care as a profession). More recent systems concepts (such as autopoiesis, role of the observer, "fitting", limits of planning in human systems) are used to develop suggestions for everyday practice of residential child care--from intake to dismissal, from crisis intervention to family education, from job satisfaction to management issues.
[Divorce as a family crisis and clinical problem--a review of recent North American literature].
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