Biomedical subjects
Publications and source records attributed to S Levin.
This article examines available information concerning the use of antimicrobial agents to prevent prosthetic device infection at the time of surgical implantation. Additionally, the authors comment on the dearth of information concerning prophylactic antibiotics prior to elective surgical or dental procedures to prevent contamination of prosthetic devices already in place.
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Sampling and analysis of aerosols generated by plasma are cutting of stainless steel have qualitatively demonstrated particle penetration of sampler prefilters utilized in the National Institute for Occupational Safety and Health (NIOSH)-type and impinger sampler analytical procedures for measuring the presence of nickel carbonyl. These results illustrate that only a small mass of nickel-containing particles need penetrate the prefilters to exaggerate greatly the inferred concentration of nickel carbonyl. Strong evidence was obtained via the chemiluminescence method that nickel carbonyl concentrations in fact were very low (less than 1 ppb).
Eye movement dysfunctions (EMDs), detectable during smooth pursuit, occur in a majority of schizophrenics and in 45% of their first-degree relatives. Previous data suggest that they represent a biologic marker for schizophrenia. To determine the mode of transmission of the schizophrenia-EMD complex, the eye movements of offspring of monozygotic and dizygotic twins were recorded. One group of twins was discordant for schizophrenia; the other group for manic depression or reactive psychosis. The data suggest that EMDs and at least some schizophrenias can be considered expressions of a single underlying trait that is transmitted by an autosomal dominant gene.
Eye movements of five schizophrenic and five normal subjects were measured with the magnetic-field search-coil technique. Subjects followed targets moving smoothly at various speeds, either unpredictably in a step-ramp fashion or predictably in a triangular wave. The tracking stimulus was either a small dot or a large, richly-textured image that occupied a large portion of the visual field. Tracking by schizophrenics was abnormal; it was punctuated by catch-up saccades that corrected for smooth following movements of inadequate velocity. We did not, however, find saccadic intrusions, such as square wave jerks. Under all tracking conditions steady-state gains (eye velocity/target velocity) and, in the case of step-ramps, average acceleration in the first 120 ms were lower in patients than in normal subjects. The differences were most pronounced for tracking of the small target, moving at the highest speed tested (30 degree/s), in the nonpredictable, step-ramp waveform. With this stimulus mean steady-state gain was 0.36 (SD +/- 0.12) for the schizophrenic patients and 0.73 (SD +/- 0.11) for the normal subjects. When the target was changed to the large-field stimulus or moved in a predictable (triangular-wave) fashion, tracking improved in both patients and normal subjects, and even more so when these features were combined.
We studied an Arab family in which two infants died of severe combined immunodeficiency caused by adenosine deaminase (ADA) deficiency. One infant had purine nucleoside phosphorylase (PNP) activity in the leucocytes only half that of normal. Four other infant siblings had previously died from infections before the age of 2 months. Hyperpigmented skin lesions preceded death in three cases. The healthy parents and three healthy siblings aged 4-9 years had varying degrees of both ADA and PNP deficiencies in both white and red cells. ADA deficiency was pronounced in two siblings, and mild in the third and in the parents, and PNP activity was severely deficient in one sibling, and moderately deficient in the parents and other two siblings, who were all well. Complete absence of ADA from white cells lead to the development of severe combined immunodeficiency, but even minimal residual ADA and PNP activity allowed maturation of the immune system with normal immune function.
The authors used the Thought Disorder Index to measure thought disorder in 23 patients with unilateral right hemisphere cortical damage, 20 patients with bipolar mania, and 25 patients with schizophrenia. There were no differences in the total amount of thought disorder in these groups, but each showed a unique pattern of thought disorder. Patients with right hemisphere damage displayed fragmented thinking, manic patients displayed playful thinking, and schizophrenic patients displayed idiosyncratic thinking. These findings support the view that thought disorder is manifested in different forms that are relatively specific to psychiatric or neurological condition.
Prostaglandins of the E series, which have been proposed as therapeutic agents for the treatment of peptic ulcers and other gastrointestinal diseases, cause hyperplasia of the gastrointestinal mucosa in experimental animals. The changes are most evident in the stomach, especially the antrum, in which the wall is thickened by hyperplasia of surface mucous cells and/or submucosal edema. In rodents, the non-glandular forestomach becomes hyperplastic and hyperkeratotic. Affected stomachs are heavier and may have a larger surface area than control stomachs. Small intestines may be heavier and have a thicker mucosa, with elongation of villi and crypts. Colonic mucosa may exhibit mild hyperplasia at very high dosages. Conflicting data exist as to whether the gastrointestinal mucosal hyperplasia is more related to increased production or decreased loss of epithelial cells.
Simultaneously occurring placenta praevia and placenta percreta is a well known yet rare obstetric complication. Cases in which invasion of chorionic villi lead to asymptomatic perforation of the uterus or bladder, rarely occur. This paper describes two such cases.
Reports on the efficacy of the Minnesota Multiphasic Personality Inventory (MMPI) for selecting patients with valid complaints of pain have been equivocal. The Mensana Clinic Back Pain Test (MPT) was able to predict, with some degree of success, patients who had a definite organic pathologic condition. However, the MMPI measures personality traits, whereas the MPT measures the impact of pain on a patient's life. To determine which of the two tests would be a better predictor of actual physical abnormalities, and hence valid pain complaints, a comparison was undertaken between the two tests. The charts of 83 patients admitted to the Neurosurgery Service of Johns Hopkins Hospital with complaints of back pain were assessed. MMPI test results, as well as test results for the MPT, were compared to the presence or absence of pathologic conditions on electromyography, nerve conduction velocity studies, thermography, myelogram, or computerized axial tomography scan. The MPT had a correlation factor of -.59700, that was significant as P = .000005. Of the 52 patients scoring 17 points or less on the MPT, 85% had objective physical abnormalities, considered moderate or severe by blind review. Of the 31 patients scoring 18 points or greater on the MPT, only 26% had objective physical findings that were considered moderate or severe. Only the F scale (faking badly) of the MMPI correlated with objective physical abnormalities (r = .21340, P less than .033). However, 60% of the patients with T scores of less than 70 on the F scale had objective findings, whereas 75% of patients with T scores greater than 70 had objective physical findings.(ABSTRACT TRUNCATED AT 250 WORDS)
IgA, IgG, IgM, and IgE levels in healthy, non-atopic, Israeli-born children aged 20 days to 16 years were analyzed and showed similar age-related values and dynamics as those of white populations found in other countries. No significant effect of sex of the individual or ethnic origin of the parents was found on the IgE values at different ages. This may indicate that total IgE levels are strongly influenced by environmental factors. Establishing tolerance limits at 97.5, 95, 75, 25 and 5th percentiles and the geometric mean provides the practitioner with more complete reference values. The use of multivariate control charts with tolerance limits from normal IgA, IgG, IgM, and IgE levels is described and is offered as an additional tool for the diagnosis of an allergic individual.
A 6-year-old Jewish Iranian girl with familial hemophagocytic lymphohistiocytosis (FHLH) is described. The course of the disease fluctuated with partial initial response to antibiotics, steroids, and supportive treatment. Subsequent cytotoxic treatment, including VP-16, Velban (vinblastine sulfate), and methotrexate (MTX) controlled the disease for a few months but the child died with a clinical picture of meningocephalitis 1.5 years later. Benign-looking lymphohistiocytic infiltrates with varying degrees of hemophagocytosis were present in the bone marrow, pleural effusion, cerebrospinal fluid (CSF), liver, and brain. Clinical and laboratory evidence of immunologic dysregulation during the disease could be demonstrated. Frequent and intense viral and bacterial infectious diseases were encountered. The laboratory examination most consistently found was the absence of natural killer (NK) cell activity against K562 target cells. The impaired activity of NK cells persisted during all stages of the disease including remission, although NK cell numbers, determined morphologically and immunophenotypically (by Leu-11, Leu-7), were normal. Natural killer activity could not be restored by interferon. Moreover, the interferon system appeared to be intact. Impaired monokin interleukin 1 (IL-I) production by peripheral blood monocytes was found and could not be restored by indomethacin. Lymphopenia, a mild decrease in T4 numbers, and subsequently, decreased proliferative response to mitogens was noted. Elevated immunoglobulin levels were found during exacerbations and viral episodes, at times accompanied by the presence of auto-antibodies. The exaggerated fatal lymphohistiocytic response typical for FHLH could be attributed to a underlying genetic pathologic dysregulation of the various immunological response pathways.
Adaptive evolution, to a large extent, is a complex combinatorial optimization process. In this article we take beginning steps towards developing a general theory of adaptive "walks" via fitter variants in such optimization processes. We introduce the basic idea of a space of entities, each a 1-mutant neighbor of many other entities in the space, and the idea of a fitness ascribed to each entity. Adaptive walks proceed from an initial entity, via fitter neighbors, to locally or globally optimal entities that are fitter than their neighbors. We develop a general theory for the number of local optima, lengths of adaptive walks, and the number of alternative local optima accessible from any given initial entity, for the baseline case of an uncorrelated fitness landscape. Most fitness landscapes are correlated, however. Therefore we develop parts of a universal theory of adaptation on correlated landscapes by adaptive processes that have sufficient numbers of mutations per individual to "jump beyond" the correlation lengths in the underlying landscape. In addition, we explore the statistical character of adaptive walks in two independent complex combinatorial optimization problems, that of evolving a specific cell type in model genetic networks, and that of finding good solutions to the traveling salesman problem. Surprisingly, both show similar statistical features, encouraging the hope that a general theory for adaptive walks on correlated and uncorrelated landscapes can be found. In the final section we explore two limits to the efficacy of selection. The first is new, and surprising: for a wide class of systems, as the complexity of the entities under selection increases, the local optima that are attainable fall progressively closer to the mean properties of the underlying space of entities. This may imply that complex biological systems, such as genetic regulatory systems, are "close" to the mean properties of the ensemble of genomic regulatory systems explored by evolution. The second limit shows that with increasing complexity and a fixed mutation rate, selection often becomes unable to pull an adapting population to those local optima to which connected adaptive walks via fitter variants exist. These beginning steps in theory development are applied to maturation of the immune response, and to the problem of radiation and stasis. Despite the limitations of the adaptive landscape metaphor, we believe that further development along the lines begun here will prove useful.
We describe a pseudoepidemic due to atypical mycobacteria contaminating the water used by a pathology laboratory and bronchoscopy suite on two floors of the same hospital building. Inspection of laboratory procedures revealed that contamination occurred during specimen processing in pathology and while obtaining the bronchoscopic specimens. Mycobacterium gordonae, Mycobacterium avium complex, and Mycobacterium scrofulaceum were identified. During an eight-month period, a total of 22 (31%) of 70 patients with positive acid-fast smears had either an illness inconsistent with tuberculosis or a known alternate diagnosis. Control was easily obtained by insertion of a 0.2-micron polymer filter into the outflow tubing of our pathology tap water-deionizing unit and the tap water source in the bronchoscopy suite. The pseudoepidemic led to additional diagnostic-therapeutic intervention, but no patient experienced delay in appropriate diagnosis. Pseudoepidemics due to atypical mycobacteria will likely be of increased importance in institutions providing care to patients with acquired immunodeficiency syndrome.
The relationship between the presence of smooth-pursuit eye-movement dysfunctions and degree of thought disorder was assessed in four groups: schizophrenics, manics, atypical psychotic patients, and normal persons. A positive relationship, constant for all groups, was found to be significant but low. Impaired eye tracking accounted for 4.22% of the total variance of thought disorder. Diagnosis accounted for over 10% of the thought-disorder variance. Although there is a tendency for those persons with poor eye tracking to have higher amounts of thought disorder than those with unimpaired eye tracking, all psychotic patients, regardless of diagnostic class, tended to have thought disorder scores in the pathological range, as measured by the Thought Disorder Index. Although the data may be viewed as supporting similar hypothetical processes that underlie pursuit dysfunctions and thought disorder, the greater likelihood exists that the coupling of thought disorder and eye-tracking dysfunctions may be explained differently in the schizophrenia and in the major affective disorders.
We have studied 288 Israeli asymptomatic male homosexuals (MHS) to determine the prevalence of antibodies to HTLVI and HTLVIII and their correlation with impairments of the immune system and serum interferon (IFN). Seropositivity for HTLVI, HTLVIII, or both was found in 1.4, 8.3, and 0%, respectively. Significant decreases in the total peripheral T cells, TH cells, and TH/TS ratio as well as elevated alpha IFN serum levels were found in the MHS group in comparison with normal controls. Although no difference in the prevalence of either immune derangements or elevated serum IFN was observed between HTLVIII/LAV-seropositive and HTLVIII/LAV-seronegative MHS, the decreases in total T cells, TH cells, and TH/TS ratios were significantly greater in the seropositive MHS. These results indicate that (a) immune impairments and IFN system activation occur commonly in homosexuals, precede their exposure to HTLVIII/LAV, and probably reflect this group's increased risk for AIDS and (b) HTLVIII/LAV infection of MHS aggravates further their preexisting immune impairments.