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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
PubMed1994

Simultaneous occurrence of chronic myelogenous leukemia and signet-ringed adenocarcinoma of the rectum. A case report with a review of the literature.

Chronic myelogenous leukemia (CML) is a pluripotent stem cell malignancy with an incidence of 1.3 per 100,000. Occasionally this uncommon disease occurs concomitantly with other neoplasia including various lymphoproliferative disorders. Its association with solid tumors, especially in young people, is decidedly rare. We report the simultaneous occurrence of CML and signet-ringed adenocarcinoma of the rectum in a 20-year-old male. A review of the literature pertinent to this topic will be briefly discussed, emphasizing characteristics of rectal carcinomas in younger age-groups as well as the unexpected association of CML with solid tumors.

Adult↗
PubMed1994

Acute hypersplenism and thrombocytopenia: a new presentation of disseminated mycobacterial infection in patients with acquired immunodeficiency syndrome.

We describe 2 patients with acquired immunodeficiency syndrome who presented with acute or subacute splenomegaly and thrombocytopenia secondary to disseminated Mycobacterium avium complex (MAC). The patients were treated for immune thrombocytopenic purpura without success. Thrombocytopenia may be a prominent feature of MAC. Our experience suggests that disseminated MAC may present with acute splenomegaly and thrombocytopenia in these patients and that a high index of suspicion for disseminated tuberculosis is indispensable in order to avoid delay in diagnosis and treatment in patients presenting with rapidly progressive splenomegaly and thrombocytopenia.

AIDS-Related Opportunistic Infections↗
PubMed1994

Carcinoid tumor of the lung and type-1 multiple endocrine neoplasia associated with persistent hypercalcemia: a case report.

The clinical and laboratory data, and histologic, electron microscopic and immunocytochemical findings of a carcinoid tumor of the lung associated with parathyroid hyperplasia and persistent hypercalcemia are described. The carcinoid tumor consists of uniform cuboidal cells with regular round vesicular nuclei and eosinophilic granular cytoplasm. The tumor cells were chromogranin and neuron-specific enolase positive. The CAT scan of the abdomen revealed an adrenal mass, 3 cm in diameter, and an enlarged body in the pancreas. Our patient is still suffering from hypercalcemia and renal colic, despite repeated parathyroid gland removal, and enucleation of the lung mass. Recent parathyroid scintigraphy with Tc revealed an enlarged parathyroid gland. The thoracic CAT scan is normal. We believe that our patient is suffering from multiple endocrine neoplasia type-1 with persistent hypercalcemia due to hyperparathyroidism.

Carcinoid Tumor↗
PubMed1994

Bacteriophages as tools for vaccine development.

The construction of live recombinant bacterial vaccines requires a reasonably sophisticated genetic system for the introduction, stabilization and expression of foreign antigen genes. Bacteriophages offer a rich collection of tools that can be used for vaccine construction, including site-specific integration-proficient vectors, non-antibiotic selectable markers and signals for efficient transcription and translation of foreign genes. We describe the characterization of a temperate phage of the mycobacteria, mycobacteriophage L5, and application of these phage studies for the construction of recombinant BCG vaccines.

BCG Vaccine↗
PubMed1993

Glutathione levels and variability in breast tumors and normal tissue.

BACKGROUND: Glutathione (GSH) is important in in vitro models of radiation and drug resistance, but its clinical relevance is uncertain. GSH levels were measured prospectively in 35 patients with breast cancer to establish normal ranges and to determine whether differences exist between tumor, lymph node metastases (when present), and normal breast tissue. METHODS: Fresh tissue was obtained immediately from discarded surgical specimens, and total GSH levels were measured with the Tietze cyclic reduction assay. When possible, multiple sites were assayed in each tumor to assess intratumor variability. RESULTS: GSH levels in primary breast tumors were more than twice the levels found in normal breast tissue, and levels in lymph node metastases were more than four times the levels in normal breast tissue. The levels of GSH in normal lymph nodes were similar to levels in normal breast tissue. GSH levels in different areas of the same breast tumor ranged from below those of normal breast tissue up to 11 times normal tissue levels. No correlation was found between tumor GSH levels and common clinical parameters such as tumor size, nodal status, stage, estrogen receptor levels, or progesterone receptor levels. CONCLUSIONS: GSH appears to be a marker of breast malignancy that is independent of hormonal receptor status and stage and may be a marker of cells with increased potential for dissemination. Because of tumor heterogeneity, multiple sites should be sampled whenever possible. Long-term clinical follow-up will be necessary to ascertain the usefulness of tumor and lymph node GSH levels in predicting prognosis.

Breast↗
PubMed1993

Disruption of sulphated glycosaminoglycans in intestinal inflammation.

We have studied the distribution and nature of sulphated glycosaminoglycans (GAGs) within normal and inflamed intestine. There is increasing evidence that these negatively charged polysaccharides, which both regulate the ability of albumin to leave the vasculature and inhibit thrombosis, may be affected by inflammatory cells and their products. We obtained samples of freshly resected intestinal tissue from eight controls, eleven patients with Crohn's disease, and six with ulcerative colitis. Sulphated GAGs were detected by means of a gold-conjugated poly-L-lysine probe, and the tissue density of anionic sites was assessed semiquantitatively by means of a Lennox graticule. In normal intestine there was staining in the vascular endothelium and the subepithelial basal lamina and throughout the extracellular matrix of the lamina propria and submucosa. Tissue from the patients with inflammatory bowel disease showed inflammation macroscopically and on histology. There were profound abnormalities of extracellular matrix GAGs, limited to the mucosa in ulcerative colitis and greatest in the submucosa in Crohn's disease. There was also substantial loss of GAGs from the subepithelial basal lamina in both disorders and from the vascular endothelium in submucosa in Crohn's disease. The extent of local GAG disruption was associated with the distribution of macrophages immunoreactive for tumour necrosis factor alpha and the activation marker RM 3/1. We suggest that inflammatory disruption of vascular and connective tissue GAGs may be an important pathogenetic mechanism, contributing to the leakage of protein and fluid, thrombosis, and tissue remodelling seen in inflammatory bowel disease.

Adolescent↗
PubMed1993

Detection of glycosaminoglycans on the surface of human umbilical vein endothelial cells using gold-conjugated poly-L-lysine with silver enhancement.

Endothelial glycosaminoglycans are important in a diverse range of vascular functions. In the course of a biochemical and histological study exploring the role of glycosaminoglycans in inflammation, we have investigated the use of gold-conjugated poly-L-lysine with silver enhancement to establish the nature and physical location of glycosaminoglycans on the surface of cultured human umbilical vein endothelial cells. Cationic gold was effective in locating anionic sites in both cultured endothelial cells and in paraffin-embedded renal tissue. By manipulating pH, and by using enzymes specific for degrading glycosaminoglycans, it was found that, at pH 1.2, staining was directed primarily at glycosaminoglycans. The surface of human umbilical vein endothelial cells was found to be extensively covered in heparan sulphate, the histological appearance of which was dependent upon the fixation procedure employed. Heparan sulphate was also seen to co-distribute with the extracellular matrix protein, fibronectin, when endothelial cultures were simultaneously stained with cationic gold and an antibody to cellular fibronectin.

Binding Sites↗
PubMed1993

Degradation of glycosaminoglycans and fibronectin on endotoxin-stimulated endothelium by adherent neutrophils: relationship to CD11b/CD18 and L-selectin expression.

Vascular endothelial injury observed in overwhelming sepsis may be caused by neutrophil-derived enzymes. Adherence to the endothelium, a prerequisite for this process, is mediated sequentially by the neutrophil adhesion molecules L-selectin and the beta 2 integrins including CD11b/CD18. The relationship between expression of these molecules, neutrophil adherence, endothelial activation, and consequent endothelial injury was assessed by changes in heparan sulfate and fibronectin matrices. Endothelial prestimulation with lipopolysaccharide caused both an increase in adherence and a generalized reduction in heparan sulfate; disruption of the fibronectin matrix occurred only on the further addition of FMLP. Although maximal disruption of these matrices was associated with elevation of neutrophil CD11b/CD18 and reduction in L-selectin expression, these changes did not determine either the nature or extent of endothelial damage. This model may provide further insights into the interrelationship between neutrophil activation and endothelial damage in gram-negative sepsis.

Antigens, CD↗
PubMed1993

Failure of tracheal aspirate cultures to define the cause of respiratory deteriorations in neonates.

The spectrum of organisms responsible for lower respiratory tract infection in chronically ventilated neonates is poorly defined. During an 18-month period 63 infants with a respiratory deterioration defined as an increase in fractional inspired O2 concentration > or = 20% and/or mean airway pressure > or = 3 cm H2O were evaluated for pulmonary infection. These infants were compared with 58 stable control ventilated infants. Tracheal aspirates for culture and Gram stain were taken from both groups and were cultured for bacteria, viruses, Chlamydia trachomatis, Ureaplasma urealyticum and Mycoplasma hominis. In addition each infant had complete blood counts with differential and chest roentgenograms evaluated. Positive tracheal aspirates defined as a heavy growth of a single or two bacterial organisms, and/or any growth of virus, Chlamydia and U. urealyticum were found in 23 of 63 study patients and 20 of 58 controls (P > 0.05). The most frequent isolate in both groups was U. urealyticum. Chest radiographs were positive (new changes, particularly atelectasis and infiltrates) more frequently in the study group than in controls, but complete blood count and tracheal aspirate Gram-stained smears were not helpful in discerning colonization from infection. We conclude that positive tracheal aspirates occur with equal frequency among infants with a clinical suspicion of lower respiratory tract infection and in "well" controls. Chest roentgenogram may be a useful adjunctive test to discriminate between colonization and lower respiratory tract infection.

Cytodiagnosis↗
PubMed1993

Kawasaki disease.

The cause of Kawasaki disease remains a mystery. Since its original description, many theories regarding the etiology of this serious childhood illness have been proposed, only to be refuted on closer scrutiny. The past year has seen important advances in our understanding of the pathophysiology of Kawasaki disease. Probably the most exciting advance has been the description of the mechanisms underlying the immunologic derangements seen in Kawasaki disease, together with evidence that this mysterious illness may be caused by a toxin that acts as a superantigen.

Child↗
PubMed1993

Deficient testicular and adrenal steroidogenesis in mutant cream (e/e) Syrian hamsters.

Coat color genes have been shown to be developmental genes with wide pleiotropic actions. The present study was undertaken to analyze the effects of mutations at the e locus of the Syrian hamster on testicular and adrenal steroidogenesis. Although no differences in body weight were detected, cream (e/e) hamsters had larger testes and smaller adrenals than wildtype (+/+) animals. Plasma testosterone levels were lower in e/e than in +/+ hamsters. However; testicular progesterone levels were higher, and 17-OH-progesterone and testosterone levels were lower in e/e when compared to +/+ hamsters. The efficiency of testicular 17-hydroxylase appear to be reduced in e/e hamsters. Adrenal progesterone levels were higher. 17-OH-progesterone, testosterone, dehydroepiandrosterone sulphate and aldosterone levels were similar, and cortisol levels were lower in e/e when compared to +/+ hamsters. The efficiencies of adrenal 17-hydroxylase and 17-hydroxysteroid dehydrogenase appear to be reduced in e/e hamsters. The present data indicate that steroidogenic deficiencies are present in the testes and adrenals of e/e hamsters, and that the gonadal alterations are more severe than the adrenal ones. The e locus, in the hamster, could be a developmental gene, or could be coding for a component in a signaling pathway under the control of such a gene.

Adrenal Cortex↗
PubMed1992

Reduction of the anticoagulant activity of glycosaminoglycans on the surface of the vascular endothelium by endotoxin and neutrophils: evaluation by an amidolytic assay.

The processes that underlie the coagulopathy observed in severe infection are not fully understood, but seem to be due to an imbalance in the antithrombotic, and prothrombotic properties of the vascular endothelium. Sulphated glycosaminoglycans (GAGs) present on the vessel wall represent an important component of the non-thrombogenic nature of the endothelium. We have modified an amidolytic assay to study the functional ability of GAGs on human umbilical vein endothelial cells (HUVECS), and investigate the effect of E. coli endotoxin and neutrophils on HUVEC surface anticoagulant activity (SAA). Neither endotoxin alone, nor separated neutrophils at lower concentrations (less than 10(6) neutrophils per ml), had major effects on endothelial SAA. When activated neutrophils were incubated with HUVECS pre-stimulated with endotoxin, a significant decrease in SAA was seen using either plasma (mean percentage of control 67.8% +/- sem 7.8; p < 0.02) or purified ATIII (mean percentage of control 69% +/- sem 4.6; p < 0.001). We suggest that alterations in endothelial surface GAGs may occur during sepsis and inflammation, and that this may have important consequences for vascular function. This system will allow the further study of the role of GAGs in the intravascular thrombosis of severe sepsis, and other inflammatory diseases.

Anticoagulants↗