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Biomedical subjects

U Martin

Publications and source records attributed to U Martin.

At least 37 records · Page 2Linked to original sources
PubMed2002

Adjuvant treatment of patients with antineutrophil cytoplasmic antibody-associated vasculitis with vitamins E and C reduces superoxide production by neutrophils.

OBJECTIVES: Neutrophils when activated generate a respiratory burst which has been implicated in the pathogenesis of primary systemic vasculitis. Neutrophils from patients with vasculitis have a greater respiratory burst than normal healthy donors. The aim of this study was to assess the effects of antioxidant treatment (vitamins E and C) on the generation of a respiratory burst from neutrophils isolated from patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis. METHODS: Neutrophils were isolated from patients with systemic vasculitis and healthy donors. Spontaneous superoxide generation was measured by the reduction of ferricytochrome c. The patients were treated with antioxidants, vitamins E and C, and spontaneous superoxide generation, vitamin C and total antioxidant capacity were measured before and after treatment. RESULTS: The treatment of the patients with antioxidants resulted in a reduction in spontaneous superoxide generation (pre-treatment 8.41+/-0.7 nmol/10(6) cells; post-treatment 5.64+/-0.6 nmol/10(6) cells; P<0.05). There was no significant difference in the superoxide generation from normal controls who did not receive treatment, measured prior to commencement of the study and 10 days later (first reading 4.81+/-0.5 nmol/10(6) cells; second reading 5.32+/-0.4 nmol/10(6) cells; P>0.05). Total antioxidant capacity increased significantly following treatment with vitamins C and E (555.4+/-142 vs. 668.6+/-186 micromol/l trolox equivalent; P=0.01) as did vitamin C concentrations (56.5+/-27 vs. 137.7+/-64 micromol/l; P=0.002). CONCLUSIONS: In this preliminary study, the treatment of patients with antioxidants, vitamins E and C, reduced neutrophil generation of superoxide and suggests that antioxidants may have an important role as adjuvant therapy. The evidence presented should form the basis of a larger randomized placebo-controlled trial of vitamins E and C as adjuvant therapy in patients with ANCA-associated systemic vasculitis.

Adult↗
PubMed2002

Induction of long-term peripheral microchimerism in non-human primates in a model of xenogeneic peripheral tolerance induction.

Xenotransplantation represents a promising solution to the ever increasing shortage of donor organs in allotransplantation. However, due to different and stronger modes of rejection, successful xenotransplantation will require different organ-protective regimes from those used in allogeneic transplantation today. Since one can not simply increase the dosage of the drugs used, immunomodulation or tolerance induction of the recipient would be the most desirable approach. Transfusion of donor leukocytes has been shown to downregulate recipient responses or even induce peripheral tolerance in small animal models. Since the infusion of donor cells represents a relatively simple approach, as one can purify and compose the inoculum exactly before infusion, we studied whether this approach can be successfully employed in a preclinical swine to non-human primate model of peripheral tolerance induction/immunomodulation. In our model, baboons underwent sequential column adsorption and complement blockade. The animals received only initial immunosuppression with cyclophosphamide. No further immunosuppression was given. Subsequently all animals received 1-3 x 10(10) porcine splenocytes i.v. Development and maintenance of chimerism was analyzed by sequential flow cytometric and PCR analyses. Other parameters studied included effects of the preparatory induction protocol. We could show that a low level of chimerism is maintained in these animals for up to 1.5 years, despite the fact that they received no additional immunosuppression after the initial one. At no time of the experiment did any animal display symptoms of poor health. Thus we demonstrate that the concept of donor leukocyte transfusion is transferable into preclinical xenotransplantation. We are currently conducting organ transplantation experiments into animals thus treated to directly analyze the immunomodulatory effect of the donor cells.

Animals↗
PubMed2001

The apoptotic capability of coxsackievirus B3 is influenced by the efficient interaction between the capsid protein VP2 and the proapoptotic host protein Siva.

Infections with coxsackievirus B3 (CVB3) are common causes of myocarditis in humans. One detail of CVB3-induced pathogenesis is apoptosis. The interaction between the capsid protein VP2 of the myocardial virus variant CVB3H3 and the proapoptotic host cell protein Siva has recently been observed. In order to characterize the interaction between both proteins more precisely, the binding activity of the CVB3H3 VP2 to Siva was compared to that of the mutant virus CVB3H310A1 VP2. We found that the asparagine at position 165 in VP2 is essential for a stable interaction with Siva influencing also the induction of apoptosis, viral spread, and inflammatory responses in vivo. Furthermore, the specific binding site of Siva to VP2 is located at amino acid positions 118-136. Together, these results show that the interaction between VP2 of CVB3H3 and Siva is a highly specific process involving distinct amino acids on both proteins that most likely influence the outcome of CVB3-caused disease.

Amino Acid Sequence↗
PubMed2001

[Fundamentals of hygiene in old-age and nursing homes. Recommendations for nursing personnel and for hygiene control by German public health offices].

New German legislative ordinances prescribe hygiene control in nursing homes and homes for the aged, e. g. the Law for Protection against Infectious Diseases and in North-Rhine Westphalia the Public Health Law. However, there are as yet no clearly defined standards of hygiene because the special features of nursing homes must be considered when applying the "Guidelines for Hospital Hygiene and Prevention of Infections" issued by the Robert Koch Institute. Hence, specific recommendations are given for hygiene of the hands, disinfection, hygienic treatment care, protective and professional clothing, washing of textiles, central kitchen, disposal of waste, house cleaning and handling of drugs and medicines.

Aged↗
PubMed2001

[How effective is the quality assurance as a result of external checking of nursing homes by the public health services].

This is a report on the external checking of nursing homes by the Public Health Services in Duisburg, Germany, focussing on hygienic problems. For a second time in the last three-and-a-half years a total of 41 such homes were inspected and a total of 4150 residents were covered. Data on the intensity of care and on the hygienic standards were evaluated and compared with the results of 1998. 70.73 % of the homes inspected employed a nurse specifically trained in hygiene-management (1998 15 %), 53.66 % used disinfectant textile cleaning and 34.39 % possessed written standards for management of infections relevant for nursing homes. 1.45 % of all residents had pressure sores III degrees and IV degrees classified according to Shea (1998: 3.37 %). In spite of significant improvements, deficits were still registered. To achieve further improvement attention should be focussed on the effectiveness of Public Health Services' activities. Increased co-operation with other institutions engaged in the external checkings as well as a closer focus on specific subjects in hygiene could be appropriate.

Communicable Disease Control↗
PubMed2001

Analysis of potential porcine endogenous retrovirus (PERV) transmission in a whole-organ xenotransplantation model without interfering microchimerism.

The question whether porcine xenografts can lead to porcine endogenous retrovirus (PERV) infection of recipients is critical for the evaluation of the safety of pig-to-man xenotransplantation. Unfortunately, polymerase chain reaction (PCR)-based analysis of potential PERV infections in nonhuman-primate whole-organ xenotransplantation models is hampered by false positive results due to chimeric porcine cells. To avoid the inherent analytical problem of xenomicrochimerism, we developed a non-life-supporting pig-to-primate kidney xenotransplantation model: porcine kidneys were transplanted, whereas the functioning recipient kidneys remained in situ. Subsequent to rejection (after 2 hours to 15 days), xenografts were removed, and recipients remained alive for up to 287 days. Immunosuppressive therapy based on cyclophosphamide, cyclosporine, and steroids was maintained for 28 days after transplantation. Using appropriate PCR assays, xenochimerism was found in tissue samples and partly even in peripheral blood leukocytes (PBLs) while the porcine kidneys were in situ. After graft removal, xenochimerism was no longer detectable, thus allowing analysis for possible PERV transmission.

Animals↗
PubMed2001

Beta-blockers in the management of hypertension in patients with type 2 diabetes mellitus: is there a role?

It has been conclusively established that treatment of hypertension in patients with type 2 (non-insulin-dependent) diabetes mellitus will significantly reduce the incidence of stroke, heart failure and progression of diabetic complications. Beta-blockers are effective antihypertensive agents which, in long term studies, have proven beneficial in reducing important clinical end-points. However nonselective beta-blockers may have a negative effect on lipid profiles and contribute to hypoglycaemic unawareness, thus preventing their use in some patients with diabetes mellitus. The development of newer and more selective beta-blockers has overcome many of these problems. In addition, some of the newer agents have novel properties such as release of nitric oxide, which theoretically would make them more attractive in patients with diabetes mellitus. Overall, the adverse metabolic effects of beta-blockers do not appear to be important in clinical practice and these agents should no longer be contraindicated in patients with type 2 diabetes mellitus. Their proven cardiovascular benefits would seem to easily tip the balance in favour of their use.

Adrenergic beta-Antagonists↗
PubMed2001

Weaning from mechanical ventilation: an update.

Many patients admitted to the intensive care unit have respiratory failure and thus require mechanical ventilation. Weaning patients from mechanical ventilation after their primary disease process has been treated can be difficult in approximately 30% of patients. Inadequacies in pulmonary gas exchange and in the performance of the respiratory muscle pump are the most common causes for failure to wean. Assessing whether a patient can be weaned from mechanical ventilation involves two major factors: (1) examining the patient for evidence of an increase in the work of breathing, and (2) measuring spontaneous breathing variables. Although different modalities have been used in weaning patients from mechanical ventilation, none has been shown to be more successful than repeated trials of spontaneous breathing.

Humans↗
PubMed2000

TatC is a specificity determinant for protein secretion via the twin-arginine translocation pathway.

The recent discovery of a ubiquitous translocation pathway, specifically required for proteins with a twin-arginine motif in their signal peptide, has focused interest on its membrane-bound components, one of which is known as TatC. Unlike most organisms of which the genome has been sequenced completely, the Gram-positive eubacterium Bacillus subtilis contains two tatC-like genes denoted tatCd and tatCy. The corresponding TatCd and TatCy proteins have the potential to be involved in the translocation of 27 proteins with putative twin-arginine signal peptides of which approximately 6-14 are likely to be secreted into the growth medium. Using a proteomic approach, we show that PhoD of B. subtilis, a phosphodiesterase belonging to a novel protein family of which all known members are synthesized with typical twin-arginine signal peptides, is secreted via the twin-arginine translocation pathway. Strikingly, TatCd is of major importance for the secretion of PhoD, whereas TatCy is not required for this process. Thus, TatC appears to be a specificity determinant for protein secretion via the Tat pathway. Based on our observations, we hypothesize that the TatC-determined pathway specificity is based on specific interactions between TatC-like proteins and other pathway components, such as TatA, of which three paralogues are present in B. subtilis.

Amino Acid Sequence↗
PubMed2000

Cloning of the murine thymic stromal lymphopoietin (TSLP) receptor: Formation of a functional heteromeric complex requires interleukin 7 receptor.

The cellular receptor for murine thymic stromal lymphopoietin (TSLP) was detected in a variety of murine, but not human myelomonocytic cell lines by radioligand binding. cDNA clones encoding the receptor were isolated from a murine T helper cell cDNA library. TSLP receptor (TSLPR) is a member of the hematopoietin receptor family. Transfection of TSLPR cDNA resulted in only low affinity binding. Cotransfection of the interleukin 7 (IL-7)Ralpha chain cDNA resulted in conversion to high affinity binding. TSLP did not activate cells from IL-7Ralpha(-/)- mice, but did activate cells from gammac(-/)- mice. Thus, the functional TSLPR requires the IL-7Ralpha chain, but not the gammac chain for signaling.

Amino Acid Sequence↗