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Biomedical subjects

A Koch

Publications and source records attributed to A Koch.

At least 127 records · Page 7Linked to original sources
PubMed2000

Indoor viable mold spores--a comparison between two cities, Erfurt (eastern Germany) and Hamburg (western Germany).

BACKGROUND: In eastern Germany, the prevalence of allergies is lower than in western Germany for both children and adults. Several reasons for this fact have been discussed, although it is still not completely understood. One purpose of the epidemiologic study "Indoor and genetic factors in asthma and allergy" (INGA) is to compare exposure to mold spores in two German cities. Therefore, 405 homes in Erfurt (east) and Hamburg (west) were visited twice by trained investigators between June 1995 and May 1997. METHODS: Samples of settled dust were taken by vacuuming from the carpet in the living room. Sieved house dust was diluted and plated on DG18 agar. The analyses were carried out in duplicate in the same laboratory. RESULTS: No significant difference could be shown for the total and for single genera (Alternaria, Aspergillus, Cladosporium, and Penicillium) in concentration of spores of viable fungi in settled house dust between Erfurt and Hamburg. Seasonal variation of the mold picture, with highest values in August, could be identified both indoors and outdoors. CONCLUSIONS: Because outdoor concentration is the main influence on indoor concentration of mold spores from June to October, we recommend sampling from November to May to evaluate exposure to indoor mold spores.

Adult↗
PubMed2000

Extracellular signal-regulated kinase 1/2 control Ca(2+)-independent force development in histamine-stimulated bovine tracheal smooth muscle.

The role of extracellular signal-regulated kinase (ERK)-1 and ERK-2 in controlling histamine-induced tone in bovine trachealis was investigated. PD 098059, an inhibitor of mitogen-activated protein kinase kinase (MKK)-1, had no effect on the histamine concentration-response relationship that described contraction. However, in the presence of EGTA, PD 098059 produced a parallel 5 fold rightwards shift of the histamine concentration-response curve without reducing the maximum response. The beta(2)-adrenoceptor agonist, procaterol, also displaced the histamine-concentration response curve to the right but the effect was much greater than that evoked by PD 098059, non-competitive and seen in the absence and presence of EGTA. A low basal level of pERK-1 and pERK-2 was always detected in untreated trachealis, which was significantly higher in EGTA-treated tissues and inhibited by PD 098059 and procaterol. Histamine markedly enhanced the phosphorylation of ERK-1 and ERK-2 by a mechanism that was also enhanced by EGTA and significantly attenuated by procaterol and PD 098059. Neither cholera toxin nor SP:-8-Br-cAMPS mimicked the ability of procaterol to dephosphorylate ERK. Similarly, neither pertussis toxin (PTX) nor RP:-8-Br-cAMPS, an inhibitor of cyclic AMP-dependent protein kinase (PKA), affected basal pERK levels or antagonized the inhibitory effect of procaterol. These data implicate the MKK-1/ERK signalling cascade in Ca(2+)-independent, histamine-induced contraction of bovine trachealis. In addition, the ability of procaterol to dephosphorylate ERK in an RP:-8-Br-cAMPS- and PTX-insensitive manner suggests that this may contribute to the anti-spasmogenic activity of beta(2)-adrenoceptor agonists by activating a novel PKA-independent pathway.

Animals↗
PubMed2000

Balloon dilatation of critical left heart stenoses in low birthweight infants.

UNLABELLED: We describe the results of balloon angioplasty in 5 infants with body weights of 850-2400 g. Three patients with severe aortic valve stenosis and two patients with isthmic coarctation of the aorta experienced relief of stenosis. Two patients with aortic valve stenosis developed thrombosis of the femoral artery; however, complete resolution of the compromised pulse occurred following thrombolytic therapy. In both patients with isthmic coarctation, pulses on the right leg remained diminished. All patients are doing well 0.28 to 3.32 y after the procedure; none has required additional therapy. Our results in a limited number of consecutive low birthweight infants show that balloon dilatation is feasible and can be performed successfully even in neonates with body weights < 1500 g. According to our experience, balloon dilatation in infants with body weights > 2000 g does not differ significantly from standard procedures. In very small infants, however, balloon angioplasty requires special precautions to avoid temperature loss. Arterial access is the major problem in small children, and requires further improvement. CONCLUSION: Balloon dilatation is feasible even in neonates < 1500 g. However, special precautions to avoid temperature loss are required and arterial access is the major problem.

Aortic Coarctation↗
PubMed2000

Capillary/myocyte mismatch in the heart in renal failure--a role for erythropoietin?

BACKGROUND: Chronic renal failure is characterized by remodeling of the heart with left ventricular hypertrophy (increasing oxygen demand) and capillary deficit leading to capillary/myocyte mismatch (decreasing oxygen supply). Erythropoietin (Epo) has known angiogenic properties causing endothelial cell activation, migration and sprouting, mediated at least in part via the JAK/STAT (Janus kinase/signal transducers and activators of transcription) pathway. In uraemic cardiac hypertrophy the presence of diminished capillary supply implies that capillary growth does not keep pace with development of hypertrophy. To investigate whether this was due to a deficit of the angiogenic hormone Epo we examined whether Epo levels are altered and whether an increase in haematocrit by administration of rhEpo influences capillary supply, i.e. capillary/myocyte mismatch in experimental renal failure. METHOD: Male Spraque-Dawley rats were either subjected to partial renal ablation or sham operation. Only modest amounts of renal tissue were removed so that the rats were not anemic. Subgroups of rats received either human (rh)Epo alone or in combination with unspecific antihypertensive treatment (dihydralazine plus furosemide) in order to control the Epo induced rise in blood pressure. Capillary supply was measured stereologically as capillary length per volume myocardium using the orientator method. RESULTS: Capillary length density was reduced by approximately 25% after partial renal ablation (3237+/-601 vs 4293+/-501 mm/mm(3) in controls). It was not statistically different in animals with partial renal ablation+rhEpo+antihypertensive treatment (3620+/-828 mm/mm(3)) compared to partial ablation alone. CONCLUSION: The study shows that lack of Epo does not cause, or contribute to, the deficit of capillary growth in the hypertrophied left ventricle of rats with renal failure. In addition, a rise in haematocrit is not accompanied by beneficial effects on alterations of cardiovascular structure in experimental renal failure.

Animals↗
PubMed2000

Prospective multicenter study of antibiotic prophylaxis in operative treatment of appendicitis.

BACKGROUND/AIMS: A prospective, multicenter observation study was conducted to investigate the effectiveness of antibiotic prophylaxis in the operative treatment of appendicitis. METHODS: Between June 1996 and May 1997, a total of 4,968 patients underwent an operation for appendicitis at 34 East German hospitals. 41.4% (n = 2,424) received perioperative antibiotic prophylaxis whereas in 58.9% of the cases this was not given. The patients who received antibiotic prophylaxis constituted a negative selection, both with regard to risk factors and to the stage of inflammation. RESULTS: In the total test group, the rate for septic disorders of wound healing amounted to 2.5% (n = 120). The use of antibiotic prophylaxis makes it possible to significant lower the incidence of postoperative septic disorders of wound healing (p < 0.001). In both conventional (0.7% with prophylaxis vs. 3.8% without) and in laparoscopic appendectomy (0 vs. 1.0%) the rate for septic disorders of wound healing can be reduced (p < 0.001). The global comparison irrespective of possible antibiotic prophylaxis shows a significant advantage for appendectomies which started with laparoscopy (p = 0.008), but in the subgroups with prophylaxis this advantage is completely neutralized (p = 0.78). CONCLUSION: From this one can deduce that conventional appendectomy with antibiotic prophylaxis comprises no higher risk of wound infection than laparoscopy, since the risk of conversion exists for every operation begun by laparoscopy. These results would lead to the conclusion that antibiotic prophylaxis should be given before every appendectomy, whether by laparoscopy or conventional methods.

Adolescent↗
PubMed2000

The electrical properties of the anterior stomach of the larval mosquito (Aedes aegypti).

The electrical properties of the anterior stomach of the larval mosquito (Aedes aegypti) were determined. At late times after cannulation, the intraluminal space constant was 936 microm, which is almost as long as the isolated tissue itself. At this time, the resistance of the apical cell membranes dominates the transcellular resistance; it is approximately 14 times the resistance of the basal cell membrane. Two physiologically distinct epithelial cell types were identified. One type has a stable basal potential of approximately 65 mV and responds to 5-hydroxytryptamine with hyperpolarization. The second cell type initially shows a basal potential of 100 mV. However, this basal potential decays in the first few minutes in parallel with the decay of the transintestinal potential. This latter cell type does not respond to 5-hydroxytryptamine.

Aedes↗
PubMed2000

[Testing, estimating, "significance"--concept and language of medical biometry].

The justification for the application of medical treatments and diagnostic methods has gained importance during the last decades. Together with scientific argumentations also the concepts of medical statistics have found a widespread use and are nowadays indispensible tools for clinical research. In publications of clinical trials, epidemiological investigations and animal experiments p-values, statistical tests and confidence intervals help the reader to evaluate the significance and relevance of the provided results. A prerequisite is a clear understanding of the concepts underlying these methodological terms. This paper presents the basic concepts of medical statistics and demonstrates the conclusions that can be drawn with the aid of these concepts.

Biometry↗
PubMed2000

[Statistical models and evaluation of observation studies].

Although randomized clinical trials can be regarded as the gold standard in many fields of clinical research, non-randomized (so called observational) studies are indispensable. Methodologic quality of such studies is at least as important as that of randomized trials but has been much less standardized. The analysis and interpretation of the results of observational studies is a very demanding job which needs a high level of knowledge and experience--medical as well as statistical. Basis for these analyses are complex statistical models the grounds and application of which are discussed in the following article.

Clinical Trials as Topic↗
PubMed2000

[Meta-analysis as a tool for gaining knowledge].

In these days, more than one clinical trial is mostly performed to evaluate a new treatment or therapeutic intervention. This necessitates a combined evaluation of their results. An integration of evidence from several trials is also helpful to determine the actual knowledge. These are the main goals of meta-analyses. Since the end of the 80s meta-analyses are widely used in clinical research. At the beginning of a meta-analysis, a protocol has to be developed. Similar to a protocol of a clinical trial, the inclusion and exclusion criteria for trials, the hypotheses and the planned analyses have to be fixed. After a careful localization of trials, a combined statistical analysis is performed. An investigation of heterogeneity, i.e., differences between study results, is indispensable. During the last years, the tool meta-analysis has been criticized. The criticism mainly results from poorly conducted meta-analyses which generated results without prespecifying hypotheses or which merely combined study results. Well-planned meta-analyses, on the contrary, have an increasing influence in clinical research.

Clinical Trials as Topic↗
PubMed2000

[CONSORT--what a proper scientific publication should supply].

The publication of the CONSORT Statement was aimed at the improvement of the quality of research reports of randomized controlled clinical trials. It contains the most important standards of high quality research. Although originally meant for randomized studies only most aspects of this statement can be applied to other kinds of clinical studies. The following--and last--article of this series on medical biostatistics presents and comments the most important criteria.

Data Interpretation, Statistical↗
PubMed2000

[Animal experiment study on pros and cons of laparoscopic interventions on the liver].

The safety of laparoscopic liver resections compared to open procedure was to be evaluated in an animal study. Besides it had to be examined, whether onco-surgical principles could be kept sufficiently. Therefore 8 one-year-old pigs underwent laparoscopic liver resections; in 2 pigs left-lateral segmental resections were performed, in 5 left-sided hemi-hepatectomies and in one right-sided hemihepatectomy. It became obvious that a control of the vessels around the v. cava inf., of the left branch of the portal vein and of the suprahepatic veins was not possible with sufficient safety. Extraction of the preparations was a further problem. According to these results laparoscopic hemihepatectomy cannot be recommended for clinical routine. Further indications for a laparoscopic operation like deroofing of liver cysts, wedge-resections or treatment of superficial liver injuries are to be accepted.

Animals↗
PubMed2000

[Quality assurance in appendicitis--what has changed? Analysis of 2 prospective multicenter quality assurance studies].

AIMS OF THE STUDY: The present study aims to determine the influence of introduction of laparoscopic techniques and of DRG (diagnosis related gains) on the quality of appendicitis therapy. PATIENTS AND METHODS: All consecutive patients admitted for suspected appendicitis were recruited into this prospective multicenter study. Two different periods of time were considered: from 1.7.1988 to 31.12.1989, 6,266 patients from 18 hospitals were included, and from 1.6.1996 to 31.5.1997, 7,398 patients from 34 institutions. RESULTS: In the first period (1988/89), 1,869 patients were treated conservatively (29.8%), 4,397 (70.2%) were operated. Histopathological analysis of the appendix documented no acute inflammation in 28.8%, the perforation rate was 8.3% and the wound infection rate 9.6%. In the second period (1996/97), 2,430 patients were treated conservatively (32.8%), in 24.9% of all operated cases, the histopathological examination shows no acute inflammation of the appendix, the perforation rate was 5.9% and the rate of wound infections 2.5%. During this second period, 33.2% of all appendectomies were performed using the laparoscope, the conversion rate was 7.2%. CONCLUSIONS: The introduction of laparoscopic techniques and of DRG did not modify the operative indications for treatment of appendicitis. An increase in the number of normal appendices removed was not observed. The number of perforations and the incidence of wound infections was significantly reduced in the second period.

Adolescent↗
PubMed1999

The adhesive binding site of cadherins revisited.

Cadherins are single-pass transmembrane proteins that, through their homophilic specificity, function in selective cell adhesion and sorting. They have a modular structure that includes an ectodomain composed of tandem 'cadherin domains,' which have a beta-sandwich topology similar to that of immunoglobulin domains. Some early experiments suggest that, for the 'classical' cadherins, the adhesive specificity is encoded in the membrane-distal amino-terminal cadherin domain. Here, we review these data, and present new data that supports this idea.

Animals↗
PubMed1999

Respiratory pattern after wet and dry chamber dives to 0.6 MPa ambient pressure in healthy males.

The purpose of this study was to evaluate respiratory effects of wet and dry hyperbaric chamber dives to 0.6 MPa ambient pressure in healthy males. There were 19 and 22 subjects who participated in two series of dives with a bottom time of 15 min and decompression times of 28 and 17 min, respectively. Airways conductance, residual volume, forced vital capacity, forced expiratory volume in 1 sec, mid expiratory flow at 25, 50 and 75% of FVC, and diffusion capacity for CO were measured before the dives, after 3 h, and after 24 h. Multivariate analysis of covariance revealed no statistically significant effects of time or the interaction between time and dry or wet environment on the measured lung function parameters. These findings suggest first that even deep air dives may not necessarily affect pulmonary function, and second, that factors related to the particular wet environment do not seem to contribute to lung function changes after dives.

Adult↗
PubMed1999

FMIP, a novel Fms-interacting protein, affects granulocyte/macrophage differentiation.

Hematopoietic cell growth, differentiation, and commitment to a restricted lineage are guided by a set of cytokines acting exclusively on cells expressing the corresponding cytokine receptor. The macrophage colony stimulating factor (M-CSF, also termed CSF-1) and its cognate receptor, the tyrosine kinase c-Fms, are essential for monocyte and macrophage development. The underlying molecular mechanism, however, is poorly understood. Here we identified a novel Fms-interacting protein (FMIP, MW 78 kDa) which binds transiently via its N-terminal 144 residues to the cytoplasmic domain of activated Fms-molecules. Binding of FMIP was paralleled by rapid tyrosine phosphorylation within the binding domain which drastically reduced its ability to associate with Fms. Binding was specific as evidenced by co-immunoprecipitation and association with recombinant GST-Fms fusion proteins. No binding was observed with the tyrosine phosphorylated cytoplasmic domains of c-Kit, TrkA, c-Met, and the insulin receptor. The role of FMIP in hematopoietic differentiation was studied in the bipotential myeloid progenitor cell line, FDC-P1Mac11. Overexpression of FMIP prevented M-CSF induced macrophage differentiation. Instead, cells differentiated into granulocytes. Our data suggest that the level of FMIP expression could form a threshold that decides about differentiation either into macrophages or into granulocytes.

Amino Acid Sequence↗
PubMed1999

[Statistical models and analysis of observational studies].

Although randomized clinical trials can be regarded as the gold standard in many fields of clinical research, non-randomized (so called observational) studies are indispensable. Methodologic quality of such studies is at least as important as that of randomized trials but has been much less standardized. The analysis and interpretation of the results of observational studies is a very demanding job which needs a high level of knowledge and experience--medical as well as statistical. Basis for these analyses are complex statistical models the grounds and application of which are discussed in the following article.

Humans↗
PubMed1999

[Testing, estimating, "significance"--concepts and terminology of medical biometry].

The justification for the application of medical treatments and diagnostic methods has gained importance during the last decades. Together with scientific argumentations also the concepts of medical statistics have found a wide-spread use and are nowadays indispensible tools for clinical research. In publications of clinical trials, epidemiological investigations and animal experiments p-values, statistical tests and confidence intervals help the reader to evaluate the significance and relevance of the provided results. A prerequisite is a clear understanding of the concepts underlying these methodological terms. This paper presents the basic concepts of medical statistics and demonstrates the conclusions that can be drawn with the aid of these concepts.

Animals↗