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Biomedical subjects

H Hofmann

Publications and source records attributed to H Hofmann.

At least 181 records · Page 10Linked to original sources
PubMed1984

[Surface analysis of intramuscular bioglass ceramic implants using pro ton-induced x-ray emission].

The method of the proton induced x-ray emission ( PIXE ) was used for the investigation of ion exchange processes on the surface of intramuscularly implanted Bioglass-Ceramics. This method allows a simultaneous analysis free from destruction in concentrations ranges of ppm for several elements. The measurements were carried out with different proton energy, in that manner a relative quantity analysis was possible in different layers. A durable two-layered surface already originates in a short time after the implantation on the implant interface. This one consists of a layer rich in calcium and phosphorus as well as a second zone rich in silicon. The meaning of this two-layered surface for the bio-activity and the bio-stability of the material is discussed.

Animals↗
PubMed1984

Fetal insulin balance: gestational diabetes and postpartal screening.

It must be determined whether high neonatal birth weight (greater than or equal to 4000 g) is due to genetic factors or to a disorder of maternal carbohydrate metabolism. Oral glucose tolerance tests are known to be unreliable during the puerperium. If the mother's carbohydrate metabolism was disturbed during pregnancy, neonatal overweight may result from fetal hyperinsulinism. This can be diagnosed by determining the insulin in the umbilical cord blood. Mature neonates of metabolically healthy women show an insulin level of 9.2 +/- 4.4 microU/ml (N = 180) in the umbilical cord blood. The third, tenth, 50th, 90th, and 97th percentiles were calculated as 1.4, 4.3, 8.8, 15.4, and 17.7 microU/ml, respectively. With insulin values over 20 microU/ml in the umbilical cord blood, a disturbance of maternal carbohydrate metabolism during pregnancy is likely. Among 4560 births in one year, 335 neonates weighed 4000 g and more, corresponding to a proportion of 7.35%. In one quarter of the infants over 4000 g, high birth weight was associated with fetal hyperinsulinism. This corresponds to a frequency of 1.8% of all births.

Birth Weight↗
PubMed1984

Intensified conventional insulin therapy for the pregnant diabetic patient.

Thirty-three normoglycemic pregnant diabetic patients (White B-R) were studied in the course of one year during 732 weeks of therapy with 176 dose adjustments of insulin to determine patterns of insulin requirements. By means of an empirical formula, the insulin requirements within a 24-hour period can be calculated. Insulin requirement in the course of pregnancy decreases significantly between the tenth and the 16th week of gestation (-12%, P = less than .001). From the 17th to the 36th week it increases slightly at first and more markedly from the 28th week onward (+ 62%), decreasing again from the 36th week onward. Insulin distribution during the day depends on whether or not a residual function of beta cells and, consequently, basal insulin secretion exists. Either four doses of regular insulin are injected or three doses of regular insulin are combined with one to two doses of variously long-acting insulin. The ideal distribution regarding the type and amount of insulin follows certain patterns and can therefore be approximated.

Blood Glucose↗
PubMed1984

Anaerobic curved rods in genital samples of women. Performance of different selective media, comparison of detection by microscopy and culture studies, and recovery from different sampling sites.

Anaerobic curved rods (CR) frequently occur in the vaginal flora of women with non-specific vaginitis, more recently referred to as bacterial vaginosis (BV). The reasons for difficulties in culturing CR include their anaerobic nature, slow rate of growth and presence in a highly mixed flora. The present study concerns the efficiency of three culture media--blood agar, a gonococcal medium, and Columbia agar--for recovery of CR. The possibility of improving selectivity by adding various antibiotics (e.g. nalidixic acid, colistin and tinidazole) to the media was also explored. The MICs for 157 CR strains and for 80 strains of anaerobic or facultatively anaerobic bacteria isolated from vaginal samples from women with BV were therefore determined. Columbia agar containing 1 micrograms/ml tinidazole in combination with either colistin (10 micrograms/ml) or nalidixic acid (15 micrograms/ml) proved the most efficient medium for recovery of CR. These antibiotic combinations effectively suppressed growth of Gardnerella vaginalis, anaerobic cocci and species of Bacteroides.--In 291 women, comparison was made of the detection of CR morphotype bacteria in methylene-blue-stained smears and the results of vaginal cultures for CR. A long variant (2-4 micron) was found in 42% by direct microscopy and 43% by culture. A short variant (approx 1 micron), which, with two exceptions, was always concomitant with the long variant, was demonstrable in only 3% of vaginal smears and in 14% of the cultures.--Vaginal samples were approximately four times more often culture-positive for CR than were cervical samples from the same women.

Bacteria, Anaerobic↗
PubMed1984

[The concept of protein profile].

From their own experience of the simultaneous immunonephelometry of eight serum proteins, the authors propose a definition of protein profile from the point of view both of laboratory technique and interpretation. The assay should be performed quickly and the results expressed diagrammatically in normalised values, in such a way that the relative variation in protein levels can be easily visualised. A protein profile should thus comprise a minimum of proteins to be measured, chosen according to protein physiopathology and the type of abnormality under investigation. Interpretation is based on inter-protein correlations that may appear or disappear depending on the underlying physiopathology. This makes it possible to study inter-protein variation and thus avoid the probabilistic "interpretation" of single proteins taken in isolation. From this approach syndromes can be divided into two groups, elementary or complex. The authors provide examples of each, and propose an interpretation model based on this dichotomy.

Blood Protein Electrophoresis↗
PubMed1983

[Clinical aspects, diagnosis and pathology of non-aortic aneurysms].

On the basis of a large autoptic material (67,352 autopsies between 1948 and 1978), clinical symptoms, diagnosis and pathologic anatomy of 140 non-aortal aneurysms (except cerebral basal arterial aneurysms) are presented. There was an accumulation beyond the 5th decade of age, among the etiologic factors atherosclerosis was predominant. 65 percent of the cases were men, 35 percent were women. Diagnosis during life time was only achieved in 16 cases (11.5 percent): in 6 cases by palpation and/or auscultation, in 4 cases by angiography, in 3 cases by an incidental intraoperative finding, in 2 cases by the help of an X-ray survey and in one case by sonography. The main reason for this low percentage of intravitally diagnosed aneurysms has to be sought in the poverty or the complete lack of clinical symptoms. If there are clinical symptoms, these are most frequently caused by a thrombosis of the aneurysm with a consecutive disturbance of arterial perfusion, and less frequently by a rupture of the aneurysm with or without compression of adjacent organs. The prerequisite for a more frequent and earlier intravital diagnosis is the inclusion of an aneurysm into differential diagnostic thinking, especially in elderly patients and unclear clinical symptomatology.

Adult↗
PubMed1983

[Hepatitis B contamination of Viennese hospital personnel].

Blood samples of 975 Viennese hospital staff members were tested for the presence of hepatitis B antigen and antibodies; a prevalence of 26% was found. It is estimated at 20% for the entire hospital personnel in Vienna. The prevalence of hepatitis B antigen and antibodies indicates the risk of infection and varies markedly with the type of hospital department; it is, however, significantly higher in every department than in the ambient population. There were no substantial differences between occupational groups, e.g. doctors, nurses, cleaning personnel etc. However, a close correlation was found to on-job time and to age. Hepatitis B vaccination after virological-serological testing is recommended for the entire hospital personnel.

Adult↗
PubMed1983

Proximal left anterior descending coronary heart disease and complex ventricular arrhythmias.

In this study, 87 consecutive patients with angiographically proven coronary artery disease (CAD, stenosis greater than 75%) underwent 24-h Holter monitoring, 76 of them having had transmural myocardial infarction, a mean of five months before evaluation. Of the total, 51 patients showed single-vessel disease, in 31 (61%) of them with involvement of the left anterior descending (LAD) artery. In 26 patients with proximal LAD stenosis or occlusion and usually large aneurysms and subsequently impaired left ventricular function relatively low prevalence of significant ventricular premature contraction (VPC, Lown greater than or equal to III) was seen. On the contrary in 19 patients with multivessel disease and proximal LAD stenosis advanced forms of VPCs were present in 63% (p less than 0.01). Further both groups differed significantly in the frequency of postinfarction angina (30% vs. 100%; p less than 0.001) and their incidence in positive exercise stress tests (15% vs. 84%; p less than 0.001). Ejection fractions were comparable in both groups (mean 45% vs. 52%). Finally 17 patients with multivessel disease but without proximal LAD lesion did not differ in any of the above mentioned parameters, when compared to the patients with single-vessel disease and proximal LAD stenosis. We conclude that impaired left ventricular function does not sufficiently explain the high risk of sudden death in postmyocardial infarction patients. The coronary and functional status of the surviving myocardium has to be taken into consideration as well.

Adult↗
PubMed1983

Evaluation of antiarrhythmic activity of prostaglandin F2 alpha in man.

Since prostaglandin (PG) F2 alpha had been shown to act anti-arrhythmically in various animal models and also in preliminary investigations in man, further evaluation of this effect was made in 30 patients with cardiac extrasystoles and in 2 patients with tachycardias. PGF2 alpha was infused intravenously at individually adapted consecutive rates from 5 to 100 micrograms/min each for at least 5 min. In the incidence of extrasystoles a mean maximum decrease of 41% (P less than 0.001) was obtained. One patient showed repeated short interruptions of a ventricular tachycardia. A dose-dependent significant rise in blood pressure and no significant influences on heart rate, PQ interval and QRS interval of the ECG were found. It is concluded that PGF2 alpha has probably no practical importance for the therapy of cardiac arrhythmias.

Adult↗
PubMed1983

Blood coagulation induced by Bothrops atrox venom: identification and properties of a factor X activator.

The coagulating activity of Bothrops atrox venom was investigated in vitro with purified fibrinogen, with normal plasma and with plasma deficient in various factors of the coagulation cascade. This study indicated that Bothrops atrox venom possesses a thrombin-like action caused by one or several serine proteases sensitive to DFP treatment, but that its clotting action is in fact mainly due to components insensitive to DFP which activate prothrombin and factor X (Stuart factor). We partially purified the DFP insensitive activator of factor X from Bothrops atrox venom and found it to be a protein of molecular weight 77,000. Analysis of the purified fraction by electrophoresis on polyacrylamide gel in the presence of SDS showed that it is mainly composed of one heavy polypeptide chain (65,000) and one light doublet (12 - 13,000). This activator is calcium-dependent and catalyzes in vitro the conversion of purified factor X into factor X alpha. By its molecular properties, it resembles the factor X activator from Vipera russellii venom rather than physiological activators.

Blood Coagulation↗
PubMed1983

Dynamics and interactions of viroids.

Viroids are single stranded circular RNA molecules of 120,000 daltons which are pathogens of certain higher plants and replicate autonomously in the host cell. Virusoids are similar to viroids in respect to size and circularity but do replicate only as a part of a larger plant virus. The structure and structural transitions have been investigated by thermodynamic, kinetic and hydrodynamic methods and have been compared to results from calculations of the most favorable native structures and the denaturation process. The algorithm of Zuker et al. was modified for the application to circular nucleic acids. For viroids the calculations confirm our earlier theoretical and experimental results about the extended native structure and the highly cooperative transition into a branched structure. Virusoids, although described in the literature as viroid-like, show less base pairing, branching in the native secondary structure, and only low cooperativity during denaturation. They resemble more closely the properties of random sequences with length, G:C content, and circularity as in viroids but sequences generated by a computer. The comparison of viroids, virusoids and circular RNA of random sequences underlines the uniqueness of viroid structure. The interactions of viroids with dye and oligonucleotide-ligands and with RNA-polymerase II from wheat germ, which enzyme replicates viroids in vitro, has been studied in order to correlate viroid structure and its ability for specific interactions. Specificity of the interactions may be interpreted on the basis of the neighbourhood of double stranded and single stranded regions. In the host cell viroids are localized in the cell nucleus; they may be detected as free nucleic acids and in high molecular weight complexes together with other RNA and proteins.

Base Sequence↗
PubMed1983

ELISA for IgM and IgG antibodies against tick-borne encephalitis virus: quantification and standardization of results.

A method for standardizing specific antibody determination by ELISA is presented. Tick-borne encephalitis (TBE)-ELISA results are expressed in arbitrary units by comparing extinction values of test sera (tested in triplicate at a fixed dilution) with the extinction-curve of a standard serum run in the same test. The standard serum was given an arbitrary value of 1000 Vienna Units, and the corresponding units for the test serum are read from the standard curve. As a standard for IgM antibody determination, a pool of sera was taken from patients with recent TBE at about the time of maximal IgM antibody production. This IgM-standard was used for a three-layer as well as for a four-layer ELISA. The IgG standard for detection of IgG antibodies in the three-layer ELISA consisted of sera from persons with a past infection. To exclude low nonspecific results only values higher then 50 Vienna Units are regarded as undoubtedly positive. This method for standardizing ELISA gives reproducible results, even when plates coated on different days with different batches of antigen were used.

Antibodies, Viral↗