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Biomedical subjects

W Schneider

Publications and source records attributed to W Schneider.

At least 19 recordsLinked to original sources
PubMed1992

[Cholesterol--a marker for multiple risk factors? A comparison between coronary disease and coronary health].

Comparison was made in a cross-sectional study between 658 patients in whom coronary arteriography had shown (n = 304) or excluded coronary artery disease (CHD) (n = 354) and a clinically healthy group as controls (n = 1658), to assess possible risk factors. Patients aged 31-40 years with CHD had the highest total cholesterol levels (286 +/- 43 mg/dl) and the highest number of risk factors (3.6 +/- 0.9) compared to patients without CHD of the same age (204 +/- 30 mg/dl; 2.0 +/- 0.5) and healthy controls (216 +/- 45 mg/dl; 1.7 +/- 0.5) (P less than 0.001). In older patients with CHD, total cholesterol levels were lower (age group 61-70 years: 231 +/- 49 mg/dl), reaching about the same level as that of patients without CHD (232 +/- 54 mg/dl) or healthy controls of the same age (228 +/- 55 mg/dl). Furthermore, it was demonstrated that increased total cholesterol concentration can indicate the presence of other risk factors. It would thus appear that the level of total cholesterol in patients with CHD is decisively influenced by age and the presence of other risk factors.

Adult↗
PubMed1992

Peroxide-dependent amino acid oxidation and chemiluminescence catalysed by magnesium-pyridoxal phosphate-glutamate complex.

Magnesium-pyridoxal-5'-phosphate-glutamate (MPPG) has been shown to ameliorate atherosclerotic symptoms in rabbits. In vitro, MPPG in the presence of peroxides such as cholesterolhydroperoxide or cumene hydroperoxide and Mn2+ ions produces "excited states" measurable as chemiluminescence or ethylene release from 1-aminocyclopropane-1-carboxylic acid (ACC). The reactions are stimulated synergistically by unsaturated fatty acids. Pyridoxal phosphate exhibits similar properties, but can be differentiated from the activities of MPPG or the sum of the components present in MPPG.

Amino Acids↗
PubMed1992

Comparison of in vitro growth characteristics of blast cell progenitors (CFU-L) in patients with myelodysplastic syndromes and acute myeloid leukemia.

Current knowledge is inadequate to explain the different patterns of blast cell accumulation in myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). We compared the growth patterns of blast cell progenitors (CFU-L) in 23 patients with advanced MDS and 32 patients with de novo AML. Circulating blast progenitors were identified in 74% of MDS and 81% of AML samples. Primary plating efficiencies (PE1) were similar in both disorders, despite marked differences in peripheral blast cell concentrations. By cytological and cytochemical examination, colonies from MDS patients were indistinguishable from those obtained in AML. Cell cycle status was assessed by loss of colony formation following short-term exposure to cytosine arabinoside. CFU-L suicide rates (median, range) were 40% (12% to 77%) in MDS and 60.5% (27% to 98%) in AML. Actively proliferating blast cell progenitors are thus not confined to AML, but are also present in the majority of MDS patients. An important difference between MDS and AML was found when self-renewal capacity of CFU-L was examined by means of secondary plating efficiencies (PE2). Colonies could be successfully replated in 74% of AML cases. PE2 showed marked heterogeneity (2 to 730 colonies/10(5) mononuclear cells), with some values indicating excessive self-renewal capacity of CFU-L. In contrast, 62% of the MDS specimens failed to produce any secondary colony growth, and PE2 in the remaining cases was low (5 to 99/10(5) MNC). We conclude that a different balance between self-renewal and determination could be responsible for a slower pace of clonal expansion in MDS, even if the proliferative activity of clonogenic cells is similar to that in AML.

Acute Disease↗
PubMed1992

[Focal nodular hyperplasia of the liver].

For several weeks a 27-year-old man had experienced a pressure sensation and noticed a spherical area of resistance in the epigastrium. On physical examination the firm, elastic tumour seemed most likely to be arising from the liver. Sonography recorded a 7.4 x 10.5 cm echo-poor structure. Computed tomography demonstrated in the tumour a central star-like, hypodense zone which filled with contrast medium, a finding typical of focal nodular hyperplasia. Functional hepatobiliary scintigraphy and histological examination of a fine-needle biopsy from the tumour (slightly enlarged hepatocytes, portal reticular fibrosis, ductular proliferation) confirmed the diagnosis. As there was no danger of rupture and no sign of local compression surgical intervention was not indicated, but regular ultrasound monitoring is planned.

Adult↗
PubMed1992

[A lethal course in pseudomembranous enterocolitis during the parenteral administration of vancomycin and imipenem].

A 48-year-old woman required mechanical ventilation after aortic valve replacement for decompensated aortic valve stenosis when bleeding complications developed and rethoracotomy had to be performed. Acute renal failure necessitated haemodialysis. Septic fever of unknown aetiology failed to respond to oxacillin, cefotaxim and tobramycin. The endotracheal cannula and central venous catheter were changed on the 24th postoperative day and the antibiotic treatment altered to 250 mg imipenem and 125 mg vancomycin three times daily intravenously. The fever soon subsided, but recurred on the 32nd postoperative day, accompanied by increasing leucocytosis. The patient was obstipated but had no intraabdominal signs. Four days later ultrasonography demonstrated thickening of the intestinal wall and coloscopy showed typical pseudomembranous colitis. Intestinal contents were positive for Clostridium difficile toxin. Despite immediate rectal and intragastric administration of 250 mg vancomycin four times daily the patient died of pseudomembranous colitis, confirmed at autopsy. The case demonstrates that vancomycin cannot always prevent the development of pseudomembranous colitis.

Colon↗
PubMed1992

Fibrinolytic mechanisms in tumor growth and spreading.

The high prevalence of hypercoagulative states in cancer patients has been known for more than a century. Venous thrombosis in gastric cancer was described by Trousseau in 1865 [55]. In 1878, Billroth observed intravascular thrombus formation in association with metastasis [4]. Thrombohemorrhagic complications regularly occur in patients with disseminated malignancy and are related to an increase in fibrinogen and fibrin turnover. During the past decade, clinicians have witnessed considerable advances in the understanding of fibrinolysis. Initially centered on the role as part of a dynamic, hemostatic balance, research began to unravel the pathophysiological contribution of fibrinolysis to tumor progression. The mechanisms of tumor invasion and metastasis formation in cancer are of critical importance, since metastasis is the major cause of treatment failure and death. It has been suggested that cell-associated proteolytic enzymes contribute to tumor aggressiveness [11, 22, 23]. Fibrinolytic mechanisms are involved in a number of physiological processes in which tissue degradation and remodeling occurs. These include disruption of the ovarian follicle during ovulation and blastocyst implantation. These events in part resemble the invasive growth of cancer [37, 47]. Inspired by this hypothesis, the role of fibrinolytic processes in tumor invasion is under intensive study.

Cell Division↗
PubMed1992

Male reduction mammoplasty in serious gynecomastias.

This article is a report on long-term followup of a total of 44 serious gynecomastia cases in the stages I-III (according to Deutinger). The treatment consisted of either a semicircular incision and subcutaneous mastectomy or a superiorly or an inferiorly based nipple transposition while performing male reduction mammoplasty. Aesthetically pleasing results could be obtained by a periareolar approach and mastectomy. This inconspicuous procedure is feasible even in massive gynecomastia cases (stage III) or in cases of male breast asymmetry. On the other hand, all cases with breast reduction plasty and nipple transposition resulted in wing-shaped, mainly broad scars, and subjectively unfavorable results. Consequently, we favor the semicircular approach in male reduction mammoplasty in treating serious gynecomastias. With regard to possible male breast cancer etiology, the histological specimen of the mammary gland in gynecomastia is excised prior to any additional liposuction for supplementary body contouring.

Follow-Up Studies↗
PubMed1992

Retinoic acid in the treatment of acute promyelocytic leukemia: inefficacy of the 13-cis isomer and induction of complete remission by the all-trans isomer complicated by thromboembolic events.

The clinical course of three patients with acute promyelocytic leukemia receiving all-trans retinoic acid (ATRA) as a single agent is reported. The first two patients were in first and second relapse of their leukemia that had occurred despite maintenance treatment with 13-cis retinoic acid after chemotherapy-induced complete remission (CR). A switch to ATRA was followed by achievement of a CR in two patients. The third patient received ATRA as first-line therapy. Two patients experienced thromboembolic complications during the phase of ATRA-induced leukocytosis. One of them died of pulmonary embolism on day 16 of treatment. The two responding patients who did not receive consolidation chemotherapy relapsed after 6 and 9 months, respectively. Increase of the ATRA dose failed to induce a new remission.

Adult↗
PubMed1992

Pediatric craniofacial surgery: comparison of milling and stereolithography for 3D model manufacturing.

To improve the planning phase for pediatric craniofacial surgery, 3D reconstructions of CT image series were performed on a personal computer. For construction of true models of the surgical site, two concepts were pursued. CT image data of six patients were used for model manufacturing by a conventional 2 1/2 axis milling system. The material used was polyurethane foam. Alternatively, in one patient a stereolithography was produced on the basis of the 3D reconstructed CT data. This new manufacturing device uses a photocurable monomer, hardened by a UV-laser. The spatial resolution of the system is about 0.1 mm. 3D-reconstructions were performed on a personal computer. Data were then transferred into a surface oriented structure to control a stereolithographic modeling device. Time for transfer was 70 min. The production of the modelled cranium took a total time of 59 h. Accuracy was found to be much higher in stereolithography than in milled models. The model served for surgical planning. The long time for production was caused by inadequate computer capacities, which are configured for much less complex objects in computer aided design. Furthermore the programs for the machine control are optimized for technical purposes. If these conditions are improved, stereolithography could be an attractive alternative to milling of medical models.

Child↗
PubMed1992

Bond strength of composites to etched and silica-coated porcelain fusing alloys.

In vitro bond strengths of two composite veneering materials to two porcelain fusing alloys were measured utilizing two storage conditions. The alloys were etched or treated with silica applied by blasted, thermal or pyrogenic techniques and then silanated. Bond strengths were higher for the Ni-Cr-Be than the Au-Pd alloy with most values greater than 18 MPa. Bond strengths to etched and silanated Au-Pd alloy were low (less than 6.5 MPa), whereas samples treated with silica and silanated had significantly higher values. Bond strengths to the Ni-Cr-Be alloy were highest with the thermal and pyrogenic silica treatments. After thermocycling, most bond strengths to the Au-Pd alloy decreased, but were the same or higher to the Ni-Cr-Be alloy. Cohesive failures of the opaquers were observed.

Analysis of Variance↗
PubMed1992

T-cell receptor gamma/delta expressing acute leukemia emerging from sideroblastic anemia: morphological, immunological, and cytogenetic features.

Striking numerical and structural chromosome abnormalities (-Y, +8, i(7q), del (10)(q24), and del (11)(q21)) were detected by cytogenetic analysis in a patient's bone marrow with morphological features of both acute lymphoblastic leukemia and myelodysplastic disorder. Surface marker analysis characterized blast cells to be CD2+ CD7+ CD3+ CD4- CD8- expressing gamma/delta-T-cell receptor antigen and coexpressing CD11b and CD16. Exhibiting an identical phenotype as the leukemic cells, a prominent gamma/delta-TCR+ lymphocyte population was found in the bone marrow as well as in the peripheral blood. Cells of the latter compartment coexpressed CD56 and HLA-DR antigens and exhibited nonspecific cytotoxic activity. In the bone marrow cells NSCA could be induced after stimulation with interleukin 2 in vitro. Morphological, immunological, and cytogenetic findings suggest that gamma/delta-T-ALL emerged from a myelodysplastic disorder after sequential steps of malignant transformation. Leukemic cells with "mixed lineage" character may provide evidence for a common progenitor cell in the bone marrow. Assuming that the leukemic cells represent the malignant counterpart of normal CD3+ gamma/delta-TCR+ cells the results may contribute to our understanding of the origin and differentiation as well as the possible steps of malignant transformation of a gamma/delta-TCR+ lymphocyte population.

Anemia, Sideroblastic↗