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Biomedical subjects

S Levin

Publications and source records attributed to S Levin.

At least 235 records · Page 13Linked to original sources
PubMed1985

Ca2+ channel blockers stimulate ileal and colonic water absorption.

The effects of calcium channel blockers on water transport in the rat ileum and distal colon were studied in vivo using the single-pass perfusion technique. Parenteral but not intraluminal verapamil, and parenteral nifedipine increased ileal water absorption, with effects lasting at least 60 min. In contrast, i.p. verapamil had no effect on rat distal colonic water absorption, whereas intraluminal verapamil significantly stimulated colonic water absorption. Similarly, perfusing the rat descending colon with low-Ca2+ Ringer's-HCO3 stimulated colonic water absorption. Verapamil was not antisecretory because the theophylline-induced decrease in ileal water transport was similar in control animals and in animals pretreated with i.p. verapamil. In addition, nifedipine stimulated active Na and Cl absorption in rabbit ileum. These studies demonstrate that the Ca2+ channel blockers verapamil and nifedipine stimulate basal absorption of water in rat ileum and distal colon in vivo, and stimulate active Na and Cl absorption in rabbit ileum in vitro. The verapamil stimulation of colonic water absorption from the luminal surface was duplicated by perfusion with a low-Ca2+ bathing solution. This suggests the presence of apical membrane Ca2+ channels in rat colon, which appear to be involved in regulation of basal water transport, and that these Ca2+ channels are in a partially open state under basal conditions. Because verapamil stimulates absorption systemically (ileum) as well as intraluminally (colon), Ca2+ channel blockers have properties that might be useful in treatment of diarrheal diseases.

Animals↗
PubMed1985

Intraoral benign mesenchymoma.

Benign mesenchymoma is a tumor composed of two or more benign mesenchymal elements in addition to fibrous connective tissue. A case of benign mesenchymoma of the lip in a 38-year-old man is presented, and the literature is reviewed.

Adult↗
PubMed1985

Interferon modulates the leukotriene C4-induced non-adherence properties of leukocytes: acquisition of an asthmatic phenotype.

We have previously shown that peripheral blood leukocytes (PBL) of asthmatic patients acquire non-adherence properties after challenge with leukotriene C4 (LTC4), whereas PBL of normal individuals do not. Hence the use of the LTC4-induced leukocyte-adherence-inhibition (LAI) assay enables one to recognise an asthmatic phenotype on the basis of the ability of PBL to respond in vitro to LTC4. To examine the possibility that alpha interferon (IFN alpha) may have relevance to the pathogenesis of bronchial asthma, various concentrations of IFN were incubated with normal PBL and the acquisition of non-adhering properties was measured. We found that following 24 h incubation with 500 U/ml IFN, normal PBL were induced to respond to a standard dose of LTC4, and this reaction was abrogated by FPL 55712 and cyclohexamide.

Adult↗
PubMed1985

Activated interferon system in healthy homosexual men.

More than 50% of a group of healthy homosexuals in Israel were found to have an activated interferon (IFN) system as evidenced by markedly elevated blood IFN levels, increased in vitro production of IFN by unstimulated peripheral blood mononuclear cells and HuIFN-alpha and HuIFN-gamma production by appropriately stimulated cells, and a surprisingly high incidence of an antiviral state of cells. This pattern resembles that found in persons with acute viral illness, and is unlike that found in normal healthy controls. The type of IFN in the blood was found to be unusual in that it was mainly HuIFN-alpha, pH 2-labile, a type of IFN found in certain collagen diseases as well as in homosexual men suffering from Kaposi's sarcoma or lymphadenopathy. Natural killer (NK) cytotoxic activity was found to be somewhat lower than that found in normal controls, although no correlation was found between blood IFN levels and NK activity. Mean (2'-5')-oligoisoadenylate synthetase levels in cell extracts were intermediate between normal controls and patients with viral illness. Likewise no correlation was found between enzyme levels and blood IFN levels. The highly activated IFN system found in certain homosexuals, as well as the increased spontaneous production of IFN by unstimulated mononuclear cells, suggest the possibility of the presence of a virus, active or latent, in these individuals. This virus could be a retrovirus such as HTLV-III or LAV which have recently been isolated from AIDS patients. The special type of IFN present could be the response to a novel virus in an unusual situation. On the basis of recent reports, we speculate that homosexuals with highly activated IFN systems who produce pH 2-labile HuIFN-alpha could be at increased risk for developing AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1985

Results of a screening method used in a 12-month stool survey for Escherichia coli O157:H7.

Escherichia coli serotype O157:H7 has been epidemiologically linked to outbreaks of hemorrhagic colitis associated with fast-food restaurants and nursing homes. Sporadic cases now exceed those associated with outbreaks. The incidence of the organism in patients with common diarrhea syndromes and in asymptomatic persons is unknown. Routine serotyping of E. coli isolates is impractical for most clinical microbiology laboratories. We developed a screening plate by utilizing sorbitol fermentation as a biochemical marker to identify organisms for serotyping. A total of 2,552 stool samples were screened. In 106 (4.1%), sorbitol-negative E. coli were identified. Of these, two were serotype O157:H7, and both produced a Vero cell toxin. One patient had hemorrhagic colitis and the other a mild, febrile, self-limited diarrhea with no other bacterial pathogen identified. This plate provides an easy, effective method of screening for sorbitol-negative E. coli, a process facilitating the selection of organisms for serotyping and one that may help clarify this organism's role in human disease.

Canada↗
PubMed1985

Interferon system in acute transient synovitis.

The interferon system of 20 children aged 2 to 11 years (mean 5 years), diagnosed as having transient synovitis of the hip by clinical criteria, was studied. The mean blood interferon concentration was significantly higher than that of normal children, and the incidence of an antiviral state of cells (in 78% of patients) was also significantly higher than in the control group. These findings are compatible with the hypothesis that the aetiology of transient synovitis is an acute, possibly unusual, viral infection.

Acute Disease↗
PubMed1985

A urine preservative system to maintain bacterial counts. A laboratory and clinical evaluation.

The urinary tract is a common site of infection in the hospitalized, institutionalized, or ambulatory patient population. Ideally, urine should be cultured immediately or refrigerated up to 24 hours for quantitative examination for microorganisms. In the evaluation of patients at their homes or in long-term care facilities, rapid plating or refrigeration may not be practical. This is also true when evaluating small children in whom external collection devices are required to obtain a specimen. Because of these limitations, we evaluated a urine preservative and transport system, the Sage Products Urine Culture Tube, in a study of 1469 clinical specimens. This tube utilizes boric acid (1.1% final concentration) as a preservative. The Urine Culture Tube was easy to use and was as effective as refrigeration in maintaining bacterial counts. This system may be particularly useful where rapid transport or refrigeration is limited.

Bacteria↗
PubMed1985

Nicotine: a different approach to treatment of obstructive sleep apnea.

Reduced upper airway muscle activity may contribute to the occurrence of obstructive apneas during sleep. There is no uniformly successful treatment of these apneas, and it is possible that agents which increase upper airway muscle activity could reduce the occurrence of obstruction during sleep. Nicotine, a known stimulant of breathing, also increases the activity of muscles which dilate the upper airway proportionally more than it does ventilation. Hence, we evaluated the effect of nicotine on apneas during the first two hours of sleep in eight patients with sleep apnea syndrome. It was concluded that nicotine reduces apneas during the early hours of sleep, and this effect may be caused by its stimulating action on upper airway muscles.

Adolescent↗
PubMed1985

Antibodies to hepatitis B surface antigen as the sole hepatitis B marker in hospital personnel.

The epidemiologic and serologic differences between hospital employees with antibodies to hepatitis B surface antigen (anti-HBs) alone or in combination with antibodies to hepatitis B core antigen (anti-HBc) were evaluated. Of 105 employees with anti-HBs, 38 (36%) did not have anti-HBc. Sera from employees with anti-HBs alone had significantly lower mean sample ratio units of anti-HBs than sera with both antibodies (15.9 +/- 43.2 as compared to 110.3 +/- 73.9, p less than 0.0005) and more commonly had less than 10 sample ratio units of anti-HBs (32 [84%] of 38 as compared to 9 [13%] of 67, p = 0.0001). The anti-HBs in sera with anti-HBs alone was predominantly IgM as shown by inactivation with 2-mercaptoethanol and the presence of anti-HBs activity in serum IgM fractions. Failure of protection from hepatitis B virus infection in persons with anti-HBs alone and the presence of nonprotective IgM anti-HBs in chimpanzees has been reported. Our data suggest the use of anti-HBs as a single serologic screening test for hepatitis B virus immunization programs may not be reliable in identifying employees with protective antibodies.

Chicago↗
PubMed1985

Interferon deficiency syndrome.

Activation of the interferon (IFN) system is an early defence mechanism against viral infections. The virus stimulates production of IFN by nucleated cells including the peripheral blood mononuclear cells (PBMC), and this IFN in turn activates several IFN-dependent immune mechanisms including the induction of an anti-viral state in cells, which prevents or retards further intracellular viral replication. In an ongoing study of 1,500 individuals of all ages and with various illnesses, we found 15 cases (representing 5% of patients with acute viral disease) in whom the IFN system response during an acute viral illness was absent or grossly deficient. There was no detectable IFN in the blood, PBMC did not produce IFN-alpha and IFN-gamma or produced minimal amounts of one of them in vitro following appropriate stimulation, and the patients' PBMC were not in an anti-viral state. These patients had severe progressive or fulminant viral disease, often ending fatally. IFN therapy appears to be beneficial in these cases, as it rapidly induced a cellular antiviral state in most cases, stimulated in vitro IFN-alpha and IFN-gamma production by PBMC, and led to rapid recovery in seven of the nine patients who received treatment for at least 3 days. In our opinion IFN replacement therapy should be commenced as early as possible in such cases, and before irreversible cell and organ damage occur.

Adolescent↗
PubMed1985

Lymphoid cells and granulocyte progenitors in early human fetal livers: immunological parameters and in vitro cellular interactions.

Human fetal liver (HFL) transplantations have been performed in infants with severe combined immunodeficiency and in patients with aplastic anemia, but the success rates have been extremely low, partly due to insufficient cell doses in grafts from a single donor. In order to explore the possible use of combining several HFL grafts from multiple donors, we studied immunological parameters as well as the in vitro responses of HFL cells from 20 fetuses, at 6 to 11 weeks of gestation, to allogeneic HFL cells and to adult lymphocytes in the mixed lymphocyte reaction (MLR), and the granulocyte-macrophage colony-forming cells (GM-CFC) assay. HFL cells of 6 to 11 weeks of gestation were found to lack populations of cells bearing surface markers of T- and B-lymphocytes and were capable of proliferating into lymphoid colonies. Virtually no MLR was found to allogeneic HFL cells or to adult lymphocytes [stimulation index (SI) 0.63 to 1.94], whereas adult lymphocytes responded normally to HFL cells (SI 3.9 to 62.0). Coculturing mixtures of allogeneic HFL cells in agar did not lead to suppression of the GM-CFC capacity of each liver. It appears that HFL at 6 to 11 weeks of gestation lack immunocompetent cells capable of provoking positive MLR in response to allogeneic HFL cells or to adult lymphocytes, and also capable of inactivating HFL-derived hematopoietic stem cells. This model may represent an in vitro counterpart for the in vivo pooling of HFL cells from multiple donors performed in order to increase graft cell dosage in man.

Adult↗
PubMed1984

Selected aspects of nosocomial infections in the 1980s.

Unusual or rare pathogens and syndromes may become significant problems in nosocomial infection. Pathogens that usually produce community-onset disease, particularly respiratory viruses, Legionella, and atypical mycobacteria, also cause nosocomial infection. Conversely, nosocomial pathogens may also produce disease in the community, as has been seen with Clostridium difficile. Contamination of parenteral and antiseptic solutions continues to be a problem in hospitals. Hospital-acquired viral infections are receiving increasing recognition. Nosocomial gastrointestinal infections, although of low frequency, are of major import because of their epidemic potential. Airborne transmission of pathogens is becoming more apparent at the same time that recognition of the importance of hand transmission creates hope for infection control. Antibiotics influence the type of microorganisms that colonize patients, but the host determines superinfection.

Air Microbiology↗