Biomedical subjects
Publications and source records attributed to J Levy.
A 6-year-old girl suffering from idiopathic hypoparathyroidism and being treated with anticonvulsive drugs developed acute heart failure due to hypocalcemia. Acute heart failure is a rare complication of hypocalcemia. The probable role of anticonvulsive drugs in provoking this complication is discussed.
The light-ear mutation in the mouse may serve as a useful model for the human inherited oculocutaneous albinisms such as the Hermansky-Pudlak and Chédiak-Higashi syndromes. The authors have investigated the kidney lysosomes of le/le mutant mice by histochemical methods. A striking increase in the staining reaction for the lysosomal enzymes beta-galactosidase and acid-phosphatase was evident in kidney cortex of the mutant mice, in comparison with +/+ controls. The lysosomal protease, cathepsin C, is also found to be elevated in the mutant. By light microscopy, there appeared to be an increase in the number of lysosomes in mutant kidney. Electron microscopy revealed the presence of large, multilamellar granules in proximal tubule cells. Analysis of sedimentation through sucrose gradients demonstrated the presence of a low-density population of lysosomes in the mutant kidney. In addition, a striking accumulation of ceroidlike pigment was observed. The molecular lesions responsible for the melanolysosomal syndromes in mice and man are still unidentified.
Neonatal infections have been caused by Streptococcus bovis, a nonenterococcal group D Streptococcus. A recent case of neonatal meningitis caused by this organism prompted a literature review regarding appropriate antibiotic therapy. Although most reports suggested penicillin therapy alone for S bovis meningitis, isolates of this organism that were as resistant to the lethal effect of penicillin as the enterococcus have been recovered. Therefor, it was recommended that until the results of minimal inhibitory concentration and minimal bactericidal concentration tests are known both an aminoglycoside and a penicillin be used simultaneously. Proved susceptibility to the penicillin would justify discontinuation of the aminoglycoside therapy. Physicians caring for neonates with S bovis should be aware that some strains may be resistant to the lethal effect of penicillin.
The use of the diving reflex to terminate a case of paroxysmal supraventricular tachycardia (PST) is described in a 2-week-old infant who presented in severe congestive heart failure with supraventricular tachycardia at a rate of 300. The infant's face was placed in a basin of ice water at 5 degrees C. for 5 seconds with manual occlusion of the infant's nostrils to prevent aspiration. The PST converted to a sinus rhythm of 120 within 3 seconds of facial immersion. The physiology of the diving reflex is reviewed and the uses and hazards of this reflex in terminating attacks of PST in infants is discussed.
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N-acetylcysteine was employed as a therapeutic agent in a 1-year, parallel, double-blind, placebo-controlled, prospective study of 22 patients with progressive systemic sclerosis (PSS). Patients were closely followed-up and were extensively evaluated at baseline, 6 and 12 months. Most parameters remained unchanged during 1 year of study in both the NAC and placebo groups, which showed the need for prolonged studies of drugs in PSS if definitive results are to be obtained. Over the year of the study the diffusing capacity decreased in both groups, while several other parameters measured both increased and decreased. Several simple measures of function and skin distensibility were tested and two (oral aperature and handspread) were reproducible and sensitive enough to measure moderate changes of disease activity. They may be useful in future trials of drug effect in PSS.
Patients with acute glomerulonephritis often are seen with signs suggesting heart failure. Whether these signs are due to fluid overload secondary to kidney damage only, or whether there is associated myocardial damage has not been elucidated. Fourteen children with acute glomerulonephritis were studied by echocardiography during the edematous phase of the disease and five months later to evaluate cardiac function in this disease. Left ventricular size and function remained normal in all children throughout the study. The most consistent finding was enlargement of the left atrium during the edematous phase with a return toward normal values five months later. There was no correlation between blood pressure and the echocardiographic findings. This study suggests that signs of heart failure in acute glomerulonephritis are not due to myocardial damage but probably reflect fluid overload.
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A two and one-half year old boy with complex congenital heart disease had Howell-Jolly bodies in his blood raising the possibility of the asplenia syndrome. A 99mTc-sulfur colloid liver-spleen scan was reported normal, but the right lobe of the abnormally reversed liver was mistaken for the spleen. The diagnosis of visceral heterotaxy (Ivemark's syndrome) was established after scanning the patient with a new radiopharmaceutical, 99mTechnetium pyridoxylidene glutamate. The agent clearly demonstrated a left-sided gall bladder, and on comparison with the sulfur colloid scan it was established that asplenia was present. Radionuclide imaging with the new generation of hepatobiliary agents is a reliable method to document asplenia and is useful in studying patients with visceral heterotaxy.
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Sex differences in the pattern and maturation of lateral asymmetries of the human brain have been recently found by a number of investigators, suggesting that sex-related factors may differentially affect the two sides of the body. In this study, asymmetries in the size of the two feet were strongly related to sex and handedness, right-handed males having larger right feet and right-handed females having larger left feet, the reverse being seen in non-right-handed individuals. Since these differences were apparent even in children younger than 6 years, the fetal sex steroids may be critical in governing the maturation of both cerebral and pedal asymmetries.
The role of extracellular Ca2+ in the regulation of islet function is investigated. Decreasing extracellular Ca2+ concentrations cause a dose-related inhibition of glucose-induced insulin release. Whereas the efflux of 45Ca from perifused islets is transiently increased on exposure to Ca2+-deprived media, it is unaffected by a partial lowering of the extracellular Ca2+ concentration. Under the latter condition, therefore, the observed reduction in the size of the islets' exchangeable calcium pool(s) appears to be due to reduced Ca2+ entry. The proper effect of glucose on Ca handling by the islets is apparently not affected by a lowering in the extracellular Ca2+ concentration. Nevertheless, in islets exposed to glucose and incubated in Ca2+-deprived media, glucose uptake and oxidation and lactate output are decreased, whereas the islet ATP level is increased, as if extracellular Ca2+ shortage were to affect not only the cellular pool of Ca regulating insulin release, but also energy-consuming processes possibly located at the cell membrane.
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Glutaraldehyde polymerized in basic aqueous solutions was found to react with low molecular weight amines, immunoglobulins and hemoglobin. The polyglutaraldehyde was covalently bound to hypdrophilic microspheres. The rate of addition of proteins to the polyglutaraldehyde-derivatized microspheres was investigated spectrophotometrically as a function of pH and temperature. The reaction of polyglutaraldehyde was found to be faster than that of the monomer. The findings led to successful labeling of human lymphocyte subpopulations.
Iodoacetate inhibits glyceraldehyde-3-phosphate dehydrogenase activity in pancreatic islets and causes a time- and dose-related inhibition of glucose oxidation and lactate output by the islets. High concentrations of the drug (0.3 mM or more) fail to affect Ba2+-induced insulin secretion but inhibit glucose-stimulated proinsulin biosynthesis, 45Ca net uptake and insulin release. A mixture of fumarate, glutamate, and pyruvate, the oxidation of which is only partially reduced by iodoacetate, fails to protect the B-cell against the inhibitory effect of the drug. These findings are compatible with the view that glycolysis plays an essential role in the process of glucose-induced insulin release. At low concentrations of iodoacetate (up to 0.2 mM), the reduction in glucose metabolism coincides with a partial inhibition of proinsulin biosynthesis. However, the expected reduction in 45Ca net uptake and subsequent insulin release is masked by a concomitant facilitating action of iodoacetate, possibly due to interference with native ionophoretic processes. It is concluded that iodoacetate is not an adequate tool to dissociate, if they are dissociable, the fuel and secretory functions of glucose.
During the past century, it has become increasingly apparent that there is a great deal of variation in the direction and degree of cerebral lateralization, a plurality of people having language and related functions strongly specialized to the left hemisphere and visuospatial functions strongly specialized to the right, with substantial minorities manifesting various deviations from this pattern. In particular, in 35%-50% of sinistrals and 1%-10% of dextrals, the right hemisphere is specialized for linguistic skills, and in some unknown fraction of the two handedness groups, verbal and/or spatial abilities are, to varying extents, bilateralized. Levy (1973) suggested that the hand posture adopted during writing might be an index of the lateral relationship between the dominant writing hand and the language hemisphere, a normal posture indicating contralateral language specialization, and an inverted posture indicating ipsilateral language specialization. In the present investigation, two tachistoscopic tests of cerebral lateralization, one measuring spatial functions and one measuring verbal function, were administered to 73 subjects classified by handedness, hand posture during writing, and sex. Among both dextral and sinistral subjects with a normal writing posture, language and spatial functions were specialized to the contralateral and ipsilateral hemispheres, respectively, and lateral differentiation of the brain was strong. The reverse was seen in subjects having an inverted writing posture. In all groups, females were less laterally differentiated than males. In 70 out of 73 subjects, the direction of cerebral laterization was accurately predicted by handedness and hand posture. The 3 subjects (2 females and 1 male) who failed to manifest the predicted relations were all left-handers having an inverted hand posture . In this group, lateral differentiation was so weak that the reliability of the tachistoscopic tests was reduced, and we attribute these three predictive failures to this cause. Thus, almost all of the variation in the lateral organization of the brain was accounted for by handedness, hand posture, and sex.