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Biomedical subjects

G Schmidt

Publications and source records attributed to G Schmidt.

At least 145 records · Page 8Linked to original sources
PubMed1996

Variability of ventricular premature complexes and mortality risk.

A method using a parameter from the field of nonlinear dynamics to quantify the variability of ventricular premature complexes (VPCs) is presented. One hundred patients with coronary artery disease and > or = 10 VPCs/hour were included in the study. The RR intervals were plotted in a three-dimensional artificial phase space, and the structures in phase space were quantified by the local scaling indices, alpha. In the frequency distribution histogram, n(alpha), for each patient, the maximum of the ventricular ectopies alpha VPC, adjusted to the VPC frequency, was assessed; alpha VPC was used as the risk indicator. Endpoints were total mortality and sudden cardiac death. During follow-up (mean 3.1 years), 28 out of 100 patients died, 16 suddenly; alpha VPC had a significant prognostic impact and was independent from other risk indicators, such as left ventricular ejection fraction (LVEF). Patients who died during follow-up were characterized by a high alpha VPC. The optimal discrimination of high risk patients and low risk patients occurred at alpha VPC = 3.0. After 4 years, the survival rate of patients with a alpha VPC > 3.0 was 59%, in contrast to 97% in patients with alpha VPC < or = 0.3. As to the sudden death mortality, the survival rates were 74% and 97%, respectively. The difference between the groups were significant for both endpoints. Patients with an increased VPC variability (i.e., alpha VPC > 3.0) were at enhanced risk of sudden death and total mortality risk; alpha VPC was independent from other risk indicators such as the LVEF or heart rate variability parameters.

Adolescent↗
PubMed1996

Augmented immunological activities of recombinant lipopolysaccharide possessing the mannose homopolymer as the O-specific polysaccharide.

Recombinant lipopolysaccharide possessing the mannose homopolymer as the O-specific polysaccharide was manufactured genetically by transforming Escherichia coli K-12 with various rfb genes capable of synthesizing the mannose homopolymer. Recombinant lipopolysaccharide exhibited levels of anticomplement activity, adjuvant activity, and regional lymph node-enlarging activity much higher than those exhibited by the original rough-type lipopolysaccharide from E. coli K-12 or lipopolysaccharide possessing the heteropolysaccharide from E. coli O111. Immunological activities of recombinant lipopolysaccharide were as strong as those of wild-type lipopolysaccharide possessing the mannose homopolymer. Characteristic activities of wild-type lipolysaccharide possessing the mannose homopolymer were exhibited by recombinant lipopolysaccharide. The abilities of lipopolysaccharide to activate B cells polyclonally and to produce cytokines did not seem to be related to the presence of the mannose homopolymer. Therefore, it was suggested that the mannose homopolymer in the O-specific polysaccharide might exclusively enhance anticomplement activity, adjuvant activity, and regional lymph node-enlarging activity among various lipid A activities.

Adjuvants, Immunologic↗
PubMed1996

Changes in renal microcirculation induced by infusion of (Fe3+)-and (Fe2+)-myoglobin during hemorrhagic hypotension in the anesthetized rat: influence of L-NAME and 8-Br-cyclic GMP.

The effects of myoglobin on renal microcirculation were studied in anesthetized rats subjected to hemorrhagic hypotension. Capillary flow distribution was determined by allowing two dyes to circulate for 3 and 1 min, respectively, freezing the left kidney and quantifying the dye distribution in histological sections by analyzing the distances of regularly spaced test points to the next dye-labeled capillary. Control experiments showed 88% of distances to be < 12 microns in the cortex [medullary outer stripe (OS): 77%, inner stripe (IS): 93%] and no distance to be > 60 microns. Myoglobin induced disturbances in intrarenal perfusion with a significantly higher potency of (Fe2+)- as compared to (Fe3+)-myoglobin. With the reduced species, the fraction of distances > 60 microns increased to 54% in the cortex (OS: 69%; IS: 67%). L-NAME, an inhibitor of nitric oxide synthesis, induced similar defects of perfusion. The cGMP analogue 8-Br-cGMP was able to nearly completely prevent these effects. The results support the view that myoglobin when released during hemorrhagic hypotension impairs renal microcirculation supposedly by scavenging the endogenous relaxing factor nitric oxide.

Anesthesia, Intravenous↗
PubMed1996

[Late results of surgical treatment of capsular ligament injury of the thumb metacarpophalageal joint].

48 patients with 49 lesions of the ligamentous apparatus of the thumb metacarpophalangeal joint were followed-up on average 32.4 months after operative treatment. Using our own scoring and grading, we evaluated the operative results by subjective and objective criteria. In 47 (95.9%) of the operated first metacarpophalangeal joints we found "very good" and "good" results. Only one (2.0%) patient showed either a "fair" or "poor" result. The statistic analysis of the examined parameters range of motion, strength of grip, and stability did not show significant differences to the uninjured side. We recommend the use of Lengemann suture.

Adolescent↗
PubMed1995

ATP-dependent inactivation of the beta-Ser339Cys mutant F1-ATPase from Escherichia coli by N-ethylmaleimide.

We introduced mutations at the highly-conserved residue Ser-339 in subunit beta of Escherichia coli F1-ATPase. The mutations beta S339Y and beta S339F abolished ATPase activity and impaired enzyme assembly. In contrast beta S339C F1 retained function to a substantial degree. N-Ethylmaleimide (NEM) at 0.2-0.3 mM inactivated beta S339C F1-ATPase by 80-95% in the presence of MgATP or MgADP but did not inactivate appreciably in absence of nucleotide or presence of EDTA. In absence of nucleotide, 0.7 mol of [14C-NEM] was incorporated into beta-subunits of 1.0 mol F1: in presence of MgATP the amount was 1.7 mol/mol, i.e. the introduced Cys residue became more accessible to reaction in the presence of MgATP. In the X-ray structure of F1 (Abrahams et al. (1994) Nature 370, 621-628) one of the catalytic nucleotide-binding domains is empty (on the "beta E subunit") and contains a cleft. Residue beta-339 lies within this cleft; the cleft does not occur in the other two beta-subunits. Our data are consistent with the conclusion that in wild-type enzyme under physiological conditions, MgATP or MgADP induce an enzyme conformation in which residue beta-Ser-339 becomes more exposed, possibly similar to the situation seen in the "beta E-subunit" in the X-ray structure.

Adenosine Diphosphate↗
PubMed1995

Repression of lipopolysaccharide biosynthesis in Escherichia coli by an antisense RNA of Acetobacter methanolicus phage Acm1.

Lysogenic Acetobacter methanolicus strains carrying the prophage Acm1 were found to be unable to synthesize both the capsular polysaccharide (CPS) and the O-specific side-chain of lipopolysaccharide (LPS) and to represent rough variants of the host bacterium. A 262 bp DNA fragment of phage Acm1, obviously required for interference with LPS biosynthesis, was cloned and expressed in Escherichia coli. Independently of the O-type, transformation of various E. coli strains with the recombinant DNA resulted in a suppression of biosynthesis of the O-specific chains. The DNA fragment of phage Acm1 contained three very short open reading frames of 21, 24, and 36 bp. However, attempts to express phage-encoded peptides were not successful. Instead, the Acm1-derived DNA fragment was shown to code for the synthesis of a trans-acting RNA molecule of 97 nucleotides, designated lbi (LPS biosynthesis-interfering) RNA. This RNA contains sequence complementarity to E. coli target RNA sequences and appears to have the ability to form intracellularly RNA hybrid duplexes with mRNA. The data presented in this study support the hypothesis that the phenotypic effect of conversion to rough-type LPS is accompanied by the expression of an antisense RNA of phage Acm1.

Acetobacter↗
PubMed1995

S fimbriae of uropathogenic Escherichia coli bind to primary human renal proximal tubular epithelial cells but do not induce expression of intercellular adhesion molecule 1.

We have recently reported an increase of expression of the intercellular adhesion molecule 1 by renal carcinoma cells in response to S fimbriae of Escherichia coli. Now we demonstrate that E. coli expressing S and P fimbriae strongly binds to human proximal tubular epithelial cells. However, in primary and simian virus 40-transfected renal tubular epithelial cells S fimbriae do not enhance the expression of intercellular adhesion molecule 1.

Bacterial Adhesion↗
PubMed1995

Capillary perfusion pattern and microvascular geometry in heterogeneous hypoxic areas of hypoperfused rat myocardium.

The origin of heterogeneities in tissue oxygenation due to low-flow ischemia was studied in hypoperfused myocardium of anesthetized rats. In frozen sections of myocardial biopsies the localization of increases in NADH fluorescence, an indicator of tissue hypoxia, was compared with microvascular flow distribution and capillary geometry. The latter parameters were accomplished through capillary labeling with indicator dyes in vivo and enzyme-histochemical staining in vitro, respectively. Most NADH-fluorescent areas were found to have developed despite sustained capillary flow. When the fractions of arterial, venous, and intermediate capillary segments were analyzed within circumscribed hypoxic fields (< 200 microns diam), frequencies of 30.7 +/- 6.1, 35.3 +/- 5.3, and 30.8 +/- 5.0%, respectively, were found. In contrast, a significantly higher fraction of arterial segments (63.2 +/- 3.3%) and a lower percentage of venous segments (16.4 +/- 2.5%) were determined in nonhypoxic islands enclosed by hypoxic tissue. These results support the view that the latter zones are located near the arterial portion of the capillary bed where their oxygenation is favored during low-flow states. This effect appears to contribute to the supply heterogeneities in hypoperfused myocardium.

Animals↗
PubMed1995

Disturbances in renal microcirculation induced by myoglobin and hemorrhagic hypotension in anesthetized rat.

The question was studied of whether myoglobin (Mb), when released into the general circulation during hemorrhagic hypotension (HH), causes disturbances of renal blood flow. In anesthetized rats 250 mg/kg Mb was intravenously infused within 1 h; HH at 50 mmHg with subsequent retransfusion was induced for 30 min. By allowing two dyes to circulate for 1 and 3 min, respectively, and detecting their localization histologically after rapid freezing of the organ, intrarenal distribution of capillary blood flow was studied. In contrast to the results obtained with Mb or HH alone, when Mb was infused during HH, the development of large areas within cortex and medulla lacking any capillary perfusion was observed. In > 70% of the tissue, a distance > 60 microns to the next dye-labeled capillary was found (in controls 0%). At this time total renal flow had decreased from 5.3 to 0.20 ml/min (HH without Mb: 5.1 to 1.1 ml/min). It is concluded that the observed changes in renal blood flow contribute to the known direct nephrotoxic potential of Mb.

Animals↗
PubMed1995

Does peace prevent homosexuality?

This study attempted to replicate a series of investigations by Gunter Dörner and his associates that concluded that more homosexual men are born in wartime than in times of peace. That conclusion is based on Dörner's belief that war induces stress in pregnant women and that stress causes a drop in fetal androgen levels which in turn leads to the development of a homosexual "orientation". The replication not only failed to support the Dörner conclusion but also found that even those cities that suffered the most severe bombing during World War II showed no evidence of increased numbers of homosexuals. The authors conclude that homosexual men can go on loving peace and getting involved in the peace movement.

Adolescent↗
PubMed1995

[Experiences after 2 years observation of a chronic alcoholic].

Doctors of legal medicine often have to act as experts when it comes to determining the influence of alcohol or drugs. For this work it would be desirable to have many years of experience in dealing with alcoholics or occasional drinkers. Therefore, drinking experiments have always been part of the training of a doctor of legal medicine, as well as playing an important role in legal practice. It would be wrong if the experience in the legal sense were to be considered sufficient for standardising the judgement of legal responsibility. However, this is often attempted. Too much schematism should be avoided with the so called per mille graduation.

Adult↗
PubMed1995

[Arthur Biedl and the beginnings of modern endocrinology. On the 125th birthday of the Austrian pathophysiologist].

Modern endocrinology began to develop at the end of the nineteenth century in four stages: the recognition and localization of endocrine glands, the experimental proof of internal secretion by means of destruction and substitution in animals, their isolation and lastly the synthesis of pure hormones. Arthur Biedl (1869-1933), an assistant of Salomon Stricker (1834-1898), was essentially involved in the first two stages of this research process. This paper presents his work from 1895 to 1914.

Austria↗
PubMed1995

[Quantitative trauma mechanics in pelvic fracture].

Quasistatic loading of the isolated pelvis and of the pelvis in situ is reported; dynamic loading with an impactor and on 90 degrees car/car side impact are then considered. The isolated pelvis was loaded laterally at the ala of the ilium and the pelvis in situ in the anterior-posterior direction in the area of the symphysis with universal dynamometer; the loading profile was a rigid disk 150 mm in diameter. Some dynamic tests were performed with an impactor with rigid disk 80 mm in diameter as impact surface; the impact was applied against the trochanter major area at a velocity of 30-35 km/h. Otherwise, the pelvic area was stressed by impact through the intrusion of the car side or by impaction of the pelvis against a rigid wall. In the tests conducted with isolated pelves, forces of 850-4850 N were measured; pelvic fractures were observed, specifically fractures of the acetabular margin, pubic bone, and ischium, and comminuted fractures of the symphysis and the iliosacral. In the impactor tests, forces of 6.5-11 kN were enough to cause, pelvic fracture except in one case, and fractures of the femoral neck were found in some cases in addition. With quasistatic anterior-posterior loading of the pelvis in situ, forces of 4,700-10,000 N were measured in cases in which fractures were found.

Accidents, Traffic↗