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Biomedical subjects

M Levin

Publications and source records attributed to M Levin.

At least 163 records · Page 9Linked to original sources

Epidermoid splenic cyst detected on a sports physical examination.

A 14-year-old female had a large, nontender abdominal mass on a routine sports physical examination. Following evaluation by ultrasound and computed tomography scan there was an initial attempt at drainage. The mass was subsequently removed. The diagnosis was epidermoid cyst of the spleen. In this report, we discuss the epidemiology and management of a splenic cyst, a rarely encountered diagnosis in adolescents, and emphasize the life-saving potential of the abdominal examination in sports medicine.

Adolescent

Hemorrhagic shock and encephalopathy: clinical, pathologic, and biochemical features.

To further define the clinical, pathologic, and biochemical features of hemorrhagic shock and encephalopathy syndrome, we studied 25 affected children (aged 3 months to 14 years) admitted to a single center between 1982 and 1985. A prodromal illness comprising vomiting, diarrhea, listlessness, and fever was present in 84% of the cases. Acute onset of shock, convulsions and coma, bleeding (or laboratory evidence of disseminated intravascular coagulation), elevated plasma activity of hepatic enzymes, acidosis, and impaired renal function was present in every case. Twenty patients died, and all the survivors are neurologically damaged. At postmortem examination, intravascular microthrombi coexisting with hemorrhages and petechiae were found in most organs. Centrilobular liver necrosis and cerebral edema were prominent features. No microbiologic cause for the disorder was identified, but decreased plasma levels of the protease inhibitors alpha 1-antitrypsin and alpha 2-macroglobulin, together with increased levels of circulating proteolytic enzymes, were frequently present. An overrepresentation of the uncommon variant phenotypes of alpha 1-antitrypsin was found in first-degree relatives of affected patients (four had the MZ phenotype, and one each the MS or MC phenotype, of 19 relatives studied). Abnormal accumulation of alpha 1-antitrypsin was detected immunohistochemically in the livers of six of the patients. Defective protease inhibitor production or release may be involved in the pathogenesis of the disorder.

Adolescent

A highly cationic protein in plasma and urine of children with steroid-responsive nephrotic syndrome.

We postulated that the reduction of surface negative charge on the glomerular capillary wall, which is believed to underlie the proteinuria of steroid-responsive nephrotic syndrome (SRNS), might be due to the presence of a cationic substance which binds to and neutralizes the negative charge on cells and membranes. Using a method to detect charge neutralizing substances based on inhibition of binding of the cationic dye Alcian blue 8GX to heparin, plasma and urine from children with SRNS were found to contain a protease-sensitive charge-neutralizing factor, which was not present in plasma or urine of healthy individuals. This factor has been partially purified from SRNS plasma and urine by ion exchange chromatography on QAE Sephadex, gel filtration on Sephadex G150, and FPLC on Mono-S. This cationic protein, which binds to and neutralizes the charge on heparin, may also neutralize the negative charge on the glomerular capillary wall and may thus be involved in the pathogenesis of SRNS.

Cations

Phenotype, cytotoxic, and helper functions of T cells from varicella zoster virus stimulated cultures of human lymphocytes.

Blood mononuclear cells (MNC) were stimulated with VZV in the form of live cell-associated virus, glutaraldehyde-fixed VZV-infected fibroblasts or an extracted VZV antigen. After 7 days of culture with live virus, IL2 receptors (IL2R) were found on CD4 and CD8 cells while cultures stimulated with fixed or extracted antigen had IL2R only on CD4 cells. Clones derived by limiting dilution from these cultures were tested for specificity by cytotoxicity to autologous VZV-superinfected B lymphoblasts, and by proliferation in the presence of antigen and antigen presenting cells. The CD8+ clones were not VZV specific in tests of cytotoxicity or proliferation. 50% of the CD4+ clones with specificity for VZV also proliferated in cultures stimulated with individual VZV glycoproteins gp I, II or III. Included amongst these were clones cytotoxic for lymphoblast targets prepared with live VZV. Most of the VZV-specific T cell clones which failed to lyse targets prepared with live VZV lysed targets prepared with heat killed VZV. Target cells were susceptible to lysis after VZV antigens were no longer demonstrable on the cell surface by immunofluorescence and monoclonal antibodies to VZV glycoproteins failed to block cytotoxicity. 5 of 8 VZV-specific CD4+ clones provided antigen-specific help to B cells for IgG antibody production. The data are consistent with the view that CD4+ T cells respond to processed VZV antigen fragments, and that these fragments include epitopes present on gp I, gp II and gp III. Additionally, some the cloned progeny of VZV specific T cells were bifunctional (expressing cytotoxicity and help for B cells) in tissue culture.

Antigens, Viral

Effect of glucocorticoid deficiency on arterial pressure in conscious spontaneously hypertensive rats.

The effect of selective glucocorticoid or mineralocorticoid deficiency upon arterial pressure was evaluated in unanesthetized adult spontaneously hypertensive rats (SHR). Adrenalectomized SHR were replaced with 6 micrograms/24 h aldosterone (ALDO), 10 microgram/24 h dexamethasone (DEX), or both aldosterone and dexamethasone (ALDO + DEX) by IP osmotic mini-pumps. These were compared to sham-operated SHR (SHAM) and adrenalectomized SHR given no steroid replacement (ADX). Drinking fluid for all groups was 1% NaCl + 2.5% glucose. Six days after adrenalectomy, intra-arterial mean arterial pressure (MAP) fell from 174 +/- 2 to 149 +/- 6 mm Hg in ALDO (n = 8, P less than .01) and from 179 +/- 4 to 125 +/- 4 in ADX (n = 6, P less than .01). In contrast, MAP rose in SHAM from 171 +/- 4 to 179 +/- 5 mm Hg (n = 7, P less than .01), in ALDO + DEX from 161 +/- 3 to 184 +/- 4 mm Hg (n = 7, P less than .01), and in DEX from 162 +/- 2 to 181 +/- 4 mm Hg (n = 7, P less than .01). The results indicate that when diet salt intake is high, glucocorticoid action is necessary for the full expression of hypertension in adult SHR.

Adrenalectomy

Early markers of the renal complications of insulin dependent diabetes mellitus.

We investigated the associations between albuminuria, metabolic control, glomerular filtration, blood pressure, and platelet function in children with insulin dependent diabetes mellitus. The geometric mean (95% tolerance levels) albumin excretion (expressed as the geometric mean albumin to creatinine ratio on two overnight urine collections (UA/UC], in 60 diabetic children was 0.72 (0.80-6.9) mg/mmol, significantly greater than in 45 normal children (geometric mean 0.41 (0.14-1.17]. Mean (SD) glomerular filtration rate, measured by 51Cr edetic acid clearance during constant infusion, was significantly greater in diabetic children (129 (20) ml/min/1.73 m2) compared with normal controls (109 (13]. Mean (SD) renal length for height standard deviation score was +0.25 (1.1); systolic blood pressure standard deviation score was 0.15 (0.65), and diastolic blood pressure was 0.51 (0.82). Spontaneous platelet aggregation, expressed as percentage fall in platelet count in stirred whole blood after 2 minutes was 17.8 (9.2)% in the diabetic compared with 12.3 (7.9)% in normal children. UA/UC correlated with renal length and of the children with UA/UC above the normal range, 70% also had a glomerular filtration rate above the normal range. There was a weak correlation between UA/UC and glycated haemoglobin (HbA1c). All children with spontaneous platelet aggregation above normal had had diabetes for more than seven years. These cross sectional data define some of the early markers and inter-relationships that may be important in the development of nephropathy.

Adolescent

Effects of systemic alkalosis on urinary magnesium excretion in the rat.

Metabolic alkalosis has previously been shown to have an antimagnesiuric influence. To further clarify this phenomenon, short-term clearance studies were performed on intact anesthetized rats subjected to 0.9% saline infusion, 0.15 M NaHCO3 infusion or acute respiratory alkalosis. The experimental protocols resulted in a similar degree of natriuresis in each of the three groups. The increase in plasma pH value was similar both in animals treated with NaHCO3 and animals with respiratory alkalosis. Filtered loads of Mg did not differ in the three experimental groups. However, only acute metabolic alkalosis was associated with a reduction in the absolute rate of Mg excretion (saline: 0.49 +/- 0.05 mu Eq/min; 0.15 M NaHCO3: 0.29 +/- 0.04 mu Eq/min; acute respiratory alkalosis: 0.48 +/- 0.03 mu Eq/min) and fractional Mg excretion (saline: 40.3 +/- 5.3%; 0.15 NaHCO3: 18.7 +/- 1.4%; acute respiratory alkalosis: 37.2 +/- 6.9%). A similar decrease in urinary Mg excretion in animals treated with bicarbonate infusion was observed following removal of the parathyroid gland. Moreover, for any given rate of urinary Na excretion, Mg excretion was lower in bicarbonate-treated animals than in rats infused with saline solution. Intact animals treated with increasing doses of NaHCO3 revealed a statistically significant inverse correlation between the Mg to Na clearance ratio and urinary and plasma bicarbonate concentration. In contrast, such a correlation was not observed during respiratory alkalosis. The findings suggest that bicarbonate ion directly stimulates tubular magnesium reabsorption independent of the presence or absence of parathyroid hormone.

Alkalosis

Clinical, radiographic, SEM evaluation and assessment of microleakage of Class II composite restorations.

The influence of incremental or bulk filling techniques, and reapplication of unfilled resin (impregnation) to the margins with an enamel bonding agent, on marginal adaptation was evaluated in Class II composite restorations by clinical, radiographic, scanning electron microscope (SEM) and dye penetration techniques. Cavities were prepared in 80 extracted permanent posterior teeth. All cavity walls were treated with polyacrylic acid for 10 seconds. The enamel was etched for 1 minute, rinsed, dried, and lined with Scotchbond. Forty cavities were filled by increments of P30 and 40 cavities in bulk. The margins of the restorations of 20 teeth in each group were re-etched for 30 seconds and Concise Enamel Bond reapplied. The clinical scores were excellent for all restorations. Radiographic examination showed twice as many bubbles in the incrementally filled restoration than in the group filled in bulk. In 53 teeth, a radiolucent area between the dentin and the restorative material was found. After sectioning, this area was found to correspond to a hard material. The SEM revealed excellent margins in the groups of teeth that were impregnated with an unfilled resin, whereas 13 teeth without impregnation showed defective margins. The dye penetration, as a test for marginal leakage, was minimal at the occlusal surface of all teeth. At the cervical surface, 10.5% of the impregnated teeth showed severe dye penetration compared to 18% of the nonimpregnated teeth. No correlation was found between dye penetration at the cervical surface and the thickness of the residual enamel in this area.(ABSTRACT TRUNCATED AT 250 WORDS)

Composite Resins

Hemolytic uremic syndrome.

HUS has now emerged as a common clinical and pathologic syndrome that may result from a variety of disease processes. On the basis of clinical and epidemiologic criteria, several distinct subgroups of the disorder have been distinguished, the most common of which are the result of infectious processes, whereas the rarer forms may be genetically determined or acquired defects in vascular homeostasis. A related group of bacterial toxins, verotoxins, and Shiga toxin, produced by a variety of species of enteric pathogens, have been implicated in the pathogenesis of typical childhood HUS. In the few years since verotoxin-producing organisms were first incriminated as the possible etiologic agents of HUS, there has been a remarkable growth in knowledge of the biology of verotoxin and its role, not only in HUS but in hemorrhagic colitis and childhood diarrhea. The availability of purified toxin and new tools for detection of verotoxin and verotoxin-producing organisms, such as monoclonal antibodies and probes for DNA hybridization, should enable definitive studies of the epidemiology and pathogenesis of verotoxin-associated HUS to be undertaken. The growing understanding of HUS should eventually lead to improved treatment and ultimately to prevention of this serious childhood disorder.

Child

Intravascular platelet activation in the hemolytic uremic syndrome.

We studied intravascular platelet activation in patients with typical (epidemic) and atypical (sporadic) HUS and found defective aggregation, decreased platelet and increased plasma serotonin in both groups. The findings were present not only on admission during the thrombocytopenic stage of the disease, but persisted for several weeks after recovery of the platelet count. Reduced endothelial PGI2 production was significantly more common in plasma from atypical than typical cases. Plasma from both typical and atypical HUS patients induced aggregation of normal platelets, but this phenomenon was unrelated to both the presence of thrombocytopenia or the stage of the disease. Serum platelet aggregating activity was higher in the atypical HUS patients, and was not associated with immune complexes detectable by polyethylene glycol precipitation. The data indicate that intravascular platelet activation is a feature of both forms of HUS, and may be initiated by different mechanisms in the two subgroups. While abnormal PGI2 synthesis appears to be important in the atypical cases, neither defective PGI2 production nor platelet aggregation by plasma factors adequately accounts for platelet activation in the majority of typical cases.

Adolescent

Acute mercury poisoning and mercurial pneumonitis from gold ore purification.

We describe four men who had symptoms of acute mercury poisoning following exposure to mercury vapor. They were attempting home gold ore purification using a gold-mercury amalgam and sulfuric acid. Three of the four patients required treatment with penicillamine. The clinical and laboratory data are presented along with pulmonary function test results. Long-term follow-up of one patient indicates residual morbidity, with continued reduction in pulmonary diffusing capacity. This suggests permanent impairment of pulmonary function despite prompt chelation therapy.

Acute Disease