Biomedical subjects

Michael Schwarz

Publications and source records attributed to Michael Schwarz.

61 records · Page 4Linked to original sources

PubMed2002

[The severity and prolonged morbidity of community acquired pneumonia caused by group A Streptococcus].

We describe a case report of a sixteen year old patient who was admitted with severe group A streptococcal (GAS) pleuro-pneumonia, underwent pleurocentesis and recovered after two weeks of hospitalization, although complete recovery lasted for another three weeks. The present publication aims to highlight the severe, prolonged and complicated course of GAS pneumonia in children which has not yet been reported in Israel. Accurate diagnosis is crucial for appropriate therapy, which is a prolonged i.v. course of penicillin.

Adolescent↗

PubMed2001

Characteristics of infection with Candida species in patients with necrotizing pancreatitis.

This study focuses on the relevance of Candida infection (albicans and non-albicans) in patients with necrotizing pancreatitis. Altogether, 92 patients with infected pancreatic necrosis were reviewed for Candida infection. All patients underwent surgical necrosectomy for infected pancreatic necrosis. Data from patients with Candida growth in intraoperative smears were compared to those obtained from patients without Candida infection. There were 22 patients (24%) with Candida infection. Patients with or without Candida infection were comparable regarding age, gender, etiology, and severity scores at admission. Candida patients suffered a higher mortality (64% vs.19%, p = 0.0001) and experienced more systemic complications (3.2 +/- 1.6 vs. 2.1 +/- 1.4; p= 0.004) than patients without Candida. Preoperative antibiotics were given significantly longer prior to Candida infection (19.0 +/- 13.2 vs. 6.4 +/- 10.3 days; p < 0.0001). With regard to the concomitant spectrum of bacteria, solitary gram-negative infection was rare in Candida patients (5% vs. 43%, p =0.0006). The presence of Candida in patients with infected pancreatic necrosis is associated with increased mortality. Our data provide evidence that application of antibiotics contributes to the development of Candida infection and to changes in the bacterial spectrum of infected necrosis with an increase in the incidence of gram-positive infection.

Adult↗

PubMedDate not supplied

Complications and follow-up after unprotected carotid artery stenting.

PURPOSE: This prospective study was undertaken to determine the success rate, complications, and outcome of carotid artery stenting (CAS) without the use of cerebral protection devices. METHODS: During 12 months, 94 high-grade stenoses of the carotid artery in 91 consecutive patients were treated. Sixty-six (70%) of the stenoses were symptomatic and 28 (30%) were asymptomatic. RESULTS: In all 94 carotid stenoses CAS was successfully performed. During the procedure and within the 30 days afterwards, there were 2 deaths and 3 major strokes in the 66 symptomatic patients, resulting in a combined death and stroke rate of 5 of 66 (7%). Only one of these complications, a major stroke, occurred during the procedure. In the 6-month follow-up, one additional major stroke occurred in a originally symptomatic patient resulting in a combined death and stroke rate of 6 of 66 (10%) for symptomatic patients at 6 months. No major complications occurred in asymptomatic patients during the procedure or in the 6-month follow-up period. At 6 months angiographic follow-up the restenosis rate with a degree of >50% was 3 of 49 (6%) and the rate with a degree of >or=70% was 1 of 49 (2%). CONCLUSIONS: Cerebral embolization during CAS is not the only cause of the stroke and death rate associated with the procedure. The use of cerebral protection devices during the procedure may therefore not prevent all major complications following CAS.

Adult↗

PubMedDate not supplied

The integrated project ReProTect: a novel approach in reproductive toxicity hazard assessment.

Validated alternative test methods are urgently needed for safety testing of drugs, chemicals and cosmetics. Whereas some animal tests for topical toxicity have been successfully replaced by alternative methods, systemic toxicity testing requires new test strategies in order to achieve an adequate safety level for the consumer. Substantial numbers of animals are required for the current in vivo assays for drugs, chemicals and cosmetics and a broad range of pioneering alternative methods were already developed. These prerequisites motivate the development of a tiered testing strategy based on alternative tests for reproductive toxicity hazard. In the Integrated Project ReProTect, a consortium set up by the European Centre for the Validation of Alternative Methods (ECVAM) takes the lead to manage the development of a testing strategy in the area of reproductive toxicity. The reproductive cycle can be broken down into well-defined sub-elements, namely male and female fertility, implantation and pre/postnatal development. In this project, in vitro, in silico and sensor technologies will be developed, leading to testing strategies, that shall be implemented and disseminated.

Adult↗

PubMedDate not supplied

Prevalidation of a rat liver foci bioassay (RLFB) based on results from 1600 rats: a study report.

A rat liver foci bioassay (RLFB) based on an initiation-promotion protocol employing preneoplastic foci of altered hepatocytes (FAH) as an endpoint, was prevalidated in 5 different laboratories. FAH were identified by immunohistochemical demonstration of glutathione-S-transferase (placental form, GSTP) and by staining with hematoxilin/eosin (H&E), and their area fraction was quantified morphometrically. The four model hepatocarcinogens N-nitrosomorpholine, 2-acetylaminofluoren, phenobarbital, and clofibrate were selected according to characteristic differences in their presumed mode of action, and tested in a total of 1,600 male and female rats at 2 different dose levels. The chemicals were found to differ characteristically in their potency and dose-response relationship to induce FAH when given alone or when administered following initiation with diethylnitrosamine. The interlaboratory variation was small for results obtained with the GSTP-stain and somewhat larger with respect to H&E. The assessment of the carcinogenic potential of the four chemicals by the different laboratories was in the same range and the nature of their dose-response relationships did not differ essentially between laboratories. Our results suggest that this RLFB is a sensitive bioassay, providing potentially valuable information for risk assessment including the classification of carcinogenic chemicals according to their mode of action.

2-Acetylaminofluorene↗

PubMedDate not supplied

Role of connexin32 and beta-catenin in tumor promotion in mouse liver.

Tumor promoters are nonmutagenic chemicals that increase the probability of cancer by accelerating the clonal expansion of cells transformed during tumor initiation. The molecular mechanisms underlying this process are only partly understood but interference with signaling pathways regulating cell division and/or cell death is likely to be important. Ras- and beta-Catenin-dependent signaling is important for both of these processes and ras and beta-catenin genes are known mutational targets in mouse hepatocarcinogenesis. About 80% of liver tumors generated in mice by a promotional regimen including phenobarbital (PB) as tumor promoter and N-nitrosodiethylamine (DEN) as initiator showed beta-catenin mutations whereas Ha-ras mutations were not detected. By contrast, tumors from mice treated with DEN alone showed a approximately 30% Ha-ras mutation prevalence but no beta-catenin mutations. This result suggests that PB-mediated promotion in mouse liver consists in a positive selection for hepatocytes harboring mutations in beta-catenin. The gap junction protein connexin 32 (Cx32) was also found to be involved in tumor promotion by PB because Cx32 gene knockout mice were almost entirely resistent to the promotional effects of the barbiturate. The link between beta-catenin-signaling and Cx32-dependent gap junctional intercellular communication, if existent, remains obscure.

Animals↗

PubMedDate not supplied

Immunohistochemical detection of activated caspases in apoptotic hepatocytes in rat liver.

In our study we tested the utility of antibodies that specifically recognize the cleaved large (active) subunits of caspase-3 and caspase-9 for immunohistochemical detection of apoptotic hepatocytes in rat liver sections using archival material from cyproterone acetate (CPA)-treated and control rats. CPA blocks apoptosis of hepatocytes and discontinuation of CPA treatment results in a syncronized wave of hepatocyte apoptosis. By comparing liver sections from CPA-treated and control rats with high and low rates of apoptosis we observed a close correlation between the occurrence of cleaved caspase-positive apoptotic figures and H&E-stained apoptotic bodies when evaluated in parallel sections. Caspase-stained figures were either immuno-positive apoptotic bodies or pre-apoptotic hepatocytes showing cytoplasmic and/or nuclear caspase-staining with otherwise normal cellular appearance. In extension of these observations we developed a double-immunohistochemical staining procedure which enables the detection of caspase-3-positive apoptotic hepatocytes within glutathione-S-transferase-P (GST-P)-positive preneoplastic liver foci. By use of this technique, inhibition of apoptosis by 2,3,7,8-tetrachlorodibenzo-p-dioxin as detected by counting of H&E-stained apoptotic bodies was found to correlate with a strong reduction of cleaved caspase-positive hepatocytes in GST-P-positive preneoplastic foci. In summary, this study demonstrates that cleaved caspase-positive apoptotic hepatocytes could be reliably identified and quantified both in normal and neoplastically transformed liver tissue.

Animals↗