Biomedical subjects

T Meister

Publications and source records attributed to T Meister.

7 recordsLinked to original sources

PubMed2003

Papillary mesothelioma of the peritoneum in the absence of asbestos exposure.

BACKGROUND: Malignant mesothelioma of the peritoneum is a very rare neoplasm, commonly associated with asbestos exposure and often rapidly fatal. Well Differentiated Papillary Mesothelioma of the Peritoneum (WDPMP) is regarded as a less aggressive variety of the tumor. Progressive ascites is often the only clinical manifestation of the disease and differentiation of WDPMP from benign mesothelial hyperplasia or adenocarcinoma is difficult. PATIENTS AND METHODS: Here we report the case of a 45-year-old patient who presented with ascites but without evidence of portal hypertension, liver disease or abdominal malignancy. On diagnostic laparoscopy small tumor nodules were found to cover the parietal peritoneum and the greater omentum and histopathologically corresponded to papillary mesothelial hyperplasia with minimal nuclear atypia. Histochemically biopsies were positive for Calretinin, Cytokeratins and Epithelial Membrane Antigen (EMA). Based on these findings the diagnosis of WDPMP was made and the patient was closely followed without primary cytostatic therapy. CONCLUSIONS: Progressive ascites was the only clinical symptom in this patient, while liver disease, portal hypertension and gastrointestinal malignancies were ruled out by clinical, laboratory and imaging techniques. Laparoscopic biopsy revealed WDPMP to be the underlying disease. Immunocytochemistry is required to establish the diagnosis of this rare malignant disorder which is even more uncommon in the absence of a history of asbestos exposure. Due to the indolent course of WDPMP therapy should only be initiated when signs of rapid tumor progression become apparent.

Asbestosis↗

PubMed2001

Overlapping functions of lysosomal acid phosphatase (LAP) and tartrate-resistant acid phosphatase (Acp5) revealed by doubly deficient mice.

To date, two lysosomal acid phosphatases are known to be expressed in cells of the monocyte/phagocyte lineage: the ubiquitously expressed lysosomal acid phosphatase (LAP) and the tartrate-resistant acid phosphatase-type 5 (Acp5). Deficiency of either acid phosphatase results in relatively mild phenotypes, suggesting that these enzymes may be capable of mutual complementation. This prompted us to generate LAP/Acp5 doubly deficient mice. LAP/Acp5 doubly deficient mice are viable and fertile but display marked alterations in soft and mineralised tissues. They are characterised by a progressive hepatosplenomegaly, gait disturbances and exaggerated foreshortening of long bones. Histologically, these animals are distinguished by an excessive lysosomal storage in macrophages of the liver, spleen, bone marrow, kidney and by altered growth plates. Microscopic analyses showed an accumulation of osteopontin adjacent to actively resorbing osteoclasts of Acp5- and LAP/Acp5-deficient mice. In osteoclasts of phosphatase-deficient mice, vacuoles were frequently found which contained fine filamentous material. The vacuoles in Acp5- and LAP/Acp5 doubly-deficient osteoclasts also contained crystallite-like features, as well as osteopontin, suggesting that Acp5 is important for processing of this protein. This is further supported by biochemical analyses that demonstrate strongly reduced dephosphorylation of osteopontin incubated with LAP/Acp5-deficient bone extracts. Fibroblasts derived from LAP/Acp5 deficient embryos were still able to dephosphorylate mannose 6-phosphate residues of endocytosed arylsulfatase A. We conclude that for several substrates LAP and Acp5 can substitute for each other and that these acid phosphatases are essential for processing of non-collagenous proteins, including osteopontin, by osteoclasts.

Acid Phosphatase↗

PubMed1999

Alternative mechanisms for trafficking of lysosomal enzymes in mannose 6-phosphate receptor-deficient mice are cell type-specific.

Viable mice nullizygous in genes encoding the 300 kDa and the 46 kDa mannose 6-phosphate receptors (MPR 300 and MPR 46) and the insulin like growth factor II (IGF II) were generated to study the trafficking of lysosomal enzymes in the absence of MPRs. The mice have an I-cell disease-like phenotype, with increase of lysosomal enzymes in serum and normal activities in tissues. Surprisingly, the ability of MPR-deficient cells to transport newly synthesized lysosomal enzymes to lysosomes and the underlying mechanisms were found to depend on the cell type. MPR-deficient thymocytes target newly synthesized cathepsin D to lysosomes via an intracellular route. In contrast, hepatocytes and fibroblasts secrete newly synthesized cathepsin D. In fibroblasts recapture of secreted lysosomal enzymes, including that of cathepsin D, is limited and results in lysosomal storage, both in vivo and in vitro, whereas recapture by hepatocytes is remarkably effective in vivo and can result in lysosomal enzyme levels even above normal.

Animals↗

PubMed1996

[Intestinal cryptosporidiosis in HIV infection: clinical features, course and therapy].

OBJECTIVE: To determine retrospectively the clinical features and course of HIV-associated intestinal Cryptosporidium infection and its response to paromomycin. PATIENTS AND METHODS: Case notes of all patients treated for cryptosporidiosis over a two-year period at an HIV out-patient clinic were analysed (26 men, four women; median CD4-lymphocyte count: 20/microliter). Median follow-up time was 6(1-22) months. RESULTS: 15 patients had persistent diarrhoea, two remained asymptomatic, seven had a remission and in five the disease took a fulminant course with severe diarrhoea ending in death within 4 months. 15 of the patients died during the period of observation, eight of them of cryptosporidiosis-associated cachexia. Mean survival time was about one year. Eight patients had multiple intestinal infections at the time the diagnosis was made and seven developed them later, which correlated with the poorer survival chances. Four patients had proven and 13 probably cryptosporidiosis-associated involvement of the biliary tract, but this did not affect the survival chances. 21 of 28 patients with diarrhoea were treated with paromomycin. In 13 of them there was for a time complete or partial response to treatment, but no response in eight. Those who responded well or partially to paromomycin had a significantly better survival chance than those without response. There was no correlation between the severity of immunosuppression and the severity of the cryptosporidiosis-associated diarrhoea, the response to paromomycin and the worse survival chance in the presence of multiple intestinal infections. CONCLUSIONS: The reasons for the different courses taken by HIV-associated cryptosporidiosis and the different therapeutic responses remain unclear. There is no known causal treatment, but 60% of patients improved temporarily on paromomycin.

Adult↗

PubMed1996

Factors influencing morbidity and mortality after cranial meningioma surgery--a multivariate analysis.

In a retrospective analysis 385 patients with a histologically defined cranial meningioma were studied to analyze the impact of characteristic factors on morbidity and mortality after modern cranial meningioma surgery. Mortality was 4.2% one month and 7.3% six months after operation. 15.6% of the patients stayed more than one month in the hospital (defined as criteria of operative morbidity). Age, poor preoperative clinical condition (ASA score), intra- and postoperative bleeding and CSF disturbances were significantly associated with a subsequent decrease of quality of life. First symptoms like intracranial hypertension, seizures, aphasia and hemiparesis were correlated with an increase of postoperative Karnowsky index. Postoperative quality of life decreased in patients with optic and other cranial nerve disturbances significantly. Tumour size, location (exception: medial sphenoid wing) and histological diagnosis did not influence surgical outcome. This information may be useful in management decisions regarding asymptomatic meningiomas in elderly and high risk patients.

Adolescent↗

PubMed1994

A new quantum chemical approach in QSAR-analysis. Parametrisation of conformational energies into molecular descriptors JMn (steric) and JSn (electronic).

Two new types of structure-related molecular descriptors, JMn and JSn, have been developed using conformational energies from quantum chemical calculations. For this purpose propipocaine (CAS 3670-68-6) was chosen as a model and 42 analogues were studied. The quantum chemical calculations were performed applying AM1 and PCILO approximation methods. Appropriate mathematical models were designed to calculate steric parameter log JM1 and electronic parameters JS1 to JS6. The values obtained for these parameters were used in multiple linear regression analysis for the evaluation of the structure-activity relationship. Furthermore, a comparison between electronic parameters JSn and sigma (Hammett) was made. The results show, that these parameters can be used successfully in predicting the biological activity of compounds in this model. Although, JS5 values are comparable to sigma-Hammett, the electronic parameter JS2 gives a better correlation in QSAR-analysis involving two parameters JS2 and log JM1.

Anesthetics, Local↗

PubMed1990

Thin-layer chromatographic screening program for commonly used beta-blockers.

This article reports thin-layer chromatographic data (corrected Rf-values; Rcf-values) of 20 commonly used beta-blockers which are regularly encountered in toxicological analysis. Silica gel was used as stationary phase and ten systems according to the proposals of the German Research Foundation (Deutsche Forschungsgemeinschaft; DFG) were chosen as solvents.

Adrenergic beta-Antagonists↗