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Biomedical subjects

H Geyer

Publications and source records attributed to H Geyer.

At least 55 records · Page 3Linked to original sources
PubMed1996

Urinary testosterone (T) to epitestosterone (E) ratios by GC/MS. I. Initial comparison of uncorrected T/E in six international laboratories.

Six laboratories in six countries collaborated to investigate the analytical method for estimating the testosterone to epitestosterone ratio (T/E) in urine by gas chromatography/mass spectrometry in the context of detecting the application of T as a doping agent in sport. The protocol specified many but not all details of reagents and instrument conditions. The design included the distribution and analysis of four urines with different T/E values, three replicates per value, and one standard. The ranges of mean T/E values for the four urines estimated by peak area (PA) were 0.32-0.42, 0.72-0.94, 0.91-1.14 and 3.19-5.48. The analyses of variance for these data and for the peak height (PH) data were significant for the laboratory factor (p < 0.0001). In addition there was a significant interaction between the urine factor and the laboratory factor which indicates the complexity of the analysis. T/E calculated using PA was not significantly different from that using PH. For within-laboratory precision all values for PH and PA were < 8.3%, and for between-laboratory precision all values were < 11.7% except for one (20.1%). The data represent a baseline for future experiments designed to elucidate the sources of within-and between-laboratory variance, and to harmonize estimates of T/E.

Analysis of Variance↗
PubMed1996

Elongation of the N-glycans of fowl plague virus hemagglutinin expressed in Spodoptera frugiperda (Sf9) cells by coexpression of human beta 1,2-N-acetylglucosaminyltransferase I.

Spodoptera frugiperda (Sf9)-cells differ markedly in their protein glycosylation capacities from vertebrate cells in that they are not able to generate complex type oligosaccharide side chains. In order to improve the oligosaccharide processing properties of these cells we have used baculovirus vectors for expression of human (beta 1,2-N-acetylglucosaminyltransferase I (hGNT-I), the enzyme catalysing the crucial step in the pathway leading to complex type N-glycans in vertebrate cells. One vector (Bac/GNT) was designed to express unmodified GNT-I protein, the second vector (Bac/tagGNT) to express GNT-I protein with a tag epitope fused to its N-terminus. In Sf9-cells infected with Bac/tagGNT-virus a protein of about 50 kDa representing hGNT-I was detected with an antiserum directed against the tag epitope. HGNT-I activity was increased at least threefold in lysates of infected cells when N-acetylglucosamine (GlcNAc)-free ovalbumine was used as substrate. To monitor hGNT-I activity in intact Sf9-cells, the glycosylation of coexpressed fowl plague virus hemagglutinin (HA) was investigated employing a galactosylation assay and chromatographic analysis of isolated HA N-glycans. Coexpression of hGNT-I resulted in an at least fourfold increase of HA carrying terminal GlcNAc-residues. The only structure detectable in this fraction was GlcNAcMan3GlcNAc2. These results show that hGNT-I is functionally active in Sf9-cells and that the N-glycans of proteins expressed in the baculovirus/insect cell system are elongated by coexpression of glycosyltransferases of vertebrate origin. Complete complex type oligosaccharide side chains were not observed when hGNT-I was overexpressed, thus supporting the concept that Sf9-cells do not contain glycosyltransferases acting after hGNT-I.

Animals↗
PubMed1996

Expanding the theoretical foundation of differential urbanization.

"Recently, the concept of differential urbanization was introduced. It conceptually links the processes of urbanization, polarization reversal, and counterurbanization across the development spectrum in the First and Third Worlds. Based on supporting evidence in developed and less developed countries, this study expands the theoretical foundation of the concept by first focusing on a graphical analysis of the processes of urbanization, polarization reversal, and counterurbanization. Secondly, it looks into the explanations given for counterurbanization. Thirdly, factors likely to influence post-counterurban migration trends are discussed, and finally, the relevance of certain causes of differential urbanization given in the literature are explored."

Demography↗
PubMed1996

N-acetyl-beta-glucosaminidase accounts for differences in glycosylation of influenza virus hemagglutinin expressed in insect cells from a baculovirus vector.

The hemagglutinin of fowl plague virus has been expressed in Spodoptera frugiperda (Sf9) cells and in Estigmene acrea cells by using a baculovirus vector. Structural analysis revealed that the endo-H-resistant N-glycans of HA from Sf9 cells were predominantly trimannosyl core oligosaccharides, whereas in E. acrea cells most of these cores were elongated by at least one terminal N-acetylglucosamine residue. To understand the difference in carbohydrate structures, enzymes involved in N-glycan processing have been analyzed. The results revealed that the different glycosylation patterns observed are due to an N-acetyl-beta-glucosaminidase activity that was found in Sf9 cells but not in E. acrea cells. This enzyme specifically used the GlcNAcMan(3)GlcNAc(2) oligosaccharide as a substrate. When N-acetyl-beta-glucosaminidase or alpha-mannosidase II was inhibited by specific inhibitors, the amount of terminal N-acetylglucosamine in hemagglutinin from Sf9 cells was significantly enhanced. These results demonstrate that N glycosylation in both cell lines follows the classical pathway up to the stage of GlcNAcMan(3)GlcNAc(2) oligosaccharide side chains. Whereas these structures are the end product in E. acrea cells, they are degraded in Sf9 cells to Man(3)GlcNAc(2) cores by N-acetyl-beta-glucosaminidase.

Acetylglucosaminidase↗
PubMed1995

Hoof horn abnormalities in Lipizzaner horses and the effect of dietary biotin on macroscopic aspects of hoof horn quality.

This study involved a macroscopic evaluation of hoof quality in 152 Lipizzaner horses (130 from Austria and 22 from other countries) and a controlled double blind trial of the effects of biotin on hoof horn growth and quality over 19 months in 42 stallions from the Spanish Riding School (SRS) in Vienna. Using a grading system that incorporated evaluation of horn wall, white line, sole and frog, the macroscopic study revealed the following: 90% of the Austrian Lipizzaners had soft white lines and crumbling, fissured horn at the bearing border of the walls; 39% of the stallions of the SRS, > 4-years-old, had medium to severe hoof horn changes. Daily administration of 20 mg biotin to a test group of horses (n = 26) and a placebo to a control group (n = 16) showed that after 9 months the test group had significantly improved compared to the beginning of the trial and the placebo group (P < 0.01). In the test group, further improvement was observed during the following 5 months and, subsequently, the same good level of hoof condition was maintained over 3 further years of observation. Growth rate of the horn wall was equal in the biotin and placebo group, being 7 mm/28 days, giving a wall renewal period of 11 months. Mean plasma biotin level of untreated horses was 350 ng/l; plasma levels of biotin supplemented horses were > 1000 ng/l. It was concluded that continuous dietary supplementation with biotin at a daily dose of 20 mg is indicated to improve and maintain hoof horn quality in horses with less than optimum quality hoof.

Animals↗
PubMed1995

Histological and physical assessment of poor hoof horn quality in Lipizzaner horses and a therapeutic trial with biotin and a placebo.

This paper represents the second part of a study searching for factors which could be responsible for an inferior hoof horn quality of the Lipizzaner horses of the Viennese Spanish Riding School (SRS) noticed in the late 1980s. It includes an evaluation of a treatment with biotin and 42 Lipizzaner horses were tested in a double blind study. The following parameters were evaluated: 1) the histology of the hoof horn in samples from the bearing border 2) the tensile strength of the coronary horn in bearing border samples and 3) the influence of biotin upon the histological changes and the tensile strength after application of 20 mg/day of biotin during 38 months. The histological alterations of bearing border specimens were assessed by use of a grading system (Grade 0 = unchanged; Grade 1 = slight changes; Grade 2 = moderate changes; Grade 3 = severe changes). Initially more than two thirds of the horses showed moderate to severe changes: microcracks visible in the transition from the middle to the inner zone of the coronary horn; separation of the sole from the coronary horn in the region within the white zone. The tensile strength of the coronary horn, with a mean of 39 N/mm2, was 13 N/mm2 lower compared with the unchanged hooves of 10 Warmblood horses, which were investigated by Küng (1991). After 19 months of biotin treatment, the horn quality showed a small but significant improvement. This could be shown by comparing the histological tissue structure before and after treatment, as well as treated animals vs. a placebo group.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

[Erysipelas and elephantiasis of the scrotum. Surgical and drug therapy].

Elephantiasis is the outcome of persistent lymphedema. It is refractory to different therapy modalities. The social approachability of patients with this disease is impaired by severe functional and cosmetic disturbances. The causal relationship between etiology and recurrent disease is demonstrated by two cases. Treatment options are discussed. Radical surgery is decisive for primary success since chronic inflammation and chronic edema support each other. Metabolic equilibrium, disinfecting skin areas and antibiotic prophylaxis are urgent steps in the successful treatment of Erysipelas disease.

Adult↗
PubMed1995

Detection of dihydrotestosterone (DHT) doping: alterations in the steroid profile and reference ranges for DHT and its 5 alpha-metabolites.

Dihydrotestosterone (DHT), a biologically active metabolite of testosterone, may be misused in sports to benefit from its anabolic and psychotropic effects. After DHT application, a significant increase of the glucuronides of DHT and its metabolites can be expected for a certain time period depending upon dose, formulation, route of administration, and in case of percutaneous administration the chainlength of the ester. DHT and its metabolites can be monitored by gas-chromatography/mass spectrometry (GC/MS) after enzymatic hydrolysis and trimethylsilylation. To investigate the extent of the alteration of the urinary steroid profile after DHT application, timely controlled experiments have been performed with: a) oral application of [16,16,17-2H3]-DHT, and b) sublingual application of a 25 mg dose of DHT. In the experiment with [16,16,17-2H3]-DHT within 24 hours about 44% of the applied dose was recovered after hydrolysis with beta-glucuronidase from E. coli as di- or tri-deuterated 5 alpha-androstane glucuronides: androsterone (33.2%), 5 alpha-androsta-ne-3 alpha,17 beta-diol (2.5%), 5 alpha-androstane-3 beta, 17 beta-diol (0.9%), DHT (7.2%). Hydrolysis with beta-glucuronidase/arylsulfatase from Helix Pomatia resulted in a about 10% higher yield except for DHT. In the study with sublingual application of 25 mg of DHT the extent of the recovery of DHT and its metabolites was in the same range as for the deuterated DHT. The urinary glucuronide concentrations of DHT, androsterone (AND), 5 alpha-androstane-3 alpha, 17 beta-diol (5 alpha A3 alpha D) and 5 alpha-androstane-3 beta,17 beta-diol (5 alpha A3 beta D) and their ratios to etiocholanolone (ETIO), 5 beta-androstane-3 alpha, 17 beta-diol (5 beta A3 alpha D) and epitestosterone (EPIT) were increased for up to 48 hours after application. For doping control purposes concentrations of DHT, 5 alpha A3 alpha D, 5 alpha A3 beta D and ratios of 5 alpha-metabolites to non 5 alpha-metabolites such as DHT/ETIO, DHT/EPIT, 5 alpha A3 alpha D/5 beta A3 alpha D, 5 alpha A3 beta D/5 beta A3 alpha D, and AND/ETIO outside the reference ranges are a proof for DHT application. Reference ranges for Asian and Caucasian male and female athletes are calculated from data bases of the Asian Games 1994, the previous Asian Games 1990 and the routine doping control samples of Caucasian athletes measured in Cologne 1994. At the occasion of the 1994 Asian Games in Hiroshima alterations in the concentrations and ratios of the DHT depending parameters for outside there reference ranges have been found and have been sanctioned on this basis by the Medical Commission of the Organisation of Olympic Council of Asia (OCA).

Adult↗
PubMed1994

Glycosylation of glycoprotein 55 encoded by the anaemia-inducing strain of Friend spleen focus-forming virus.

Normal rat kidney cells, non-productively infected with the anaemia-inducing variant of Friend spleen focus-forming virus (F-SFFVA), were metabolically labelled with [2-3H]mannose. The primary translation product of the viral envelope gene (env), representing a glycoprotein with an apparent molecular M(r) of 55,000 (gp55), was isolated from cell lysates by immunoaffinity chromatography and purified by preparative SDS/PAGE. Radiolabelled oligosaccharides, released from tryptic glycopeptides by treatment with endo-beta-N-acetylglucosaminidase H, were characterized chromatographically, by enzymic digestion and by acetolysis. The results revealed that F-SFFVA gp55 obtained from this source carried predominantly oligomannose type sugar chains with five to nine mannoses. As a characteristic feature, glycans with seven to nine mannoses contained, in part, an additional glucose residue. Although the amount of glucosylated species found was higher in F-SFFVA gp55 (about 25% of total endo-H-sensitive oligosaccharides) than in gp55 of the corresponding polycythaemia-inducing variant (F-SFFVP, 16.3%), the overall glycosylation pattern of the F-SFFVA env product closely resembled that of F-SFFVP gp55 [Strube et al. (1988) J Biol Chem 263:3762-71]. Hence, our results demonstrate that the different intracellular processing and transport of the primary F-SFFVA env product cannot be attributed to aberrant trimming of its oligomannose type glycans.

Animals↗
PubMed1994

Oligosaccharide profiles of HIV-2 external envelope glycoprotein: dependence on host cells and virus isolates.

The glycosylation pattern of the external envelope glycoprotein of human immunodeficiency virus type 2 (HIV-2) was studied in dependence on host cells and virus isolates. Strains HIV-2ALT, HIV-2ROD and HIV-2D194, differing in their biological properties and in the amino acid sequences of their env genes, were propagated in MOLT4, HUT78 and U937 cells, in human peripheral blood lymphocytes and monocytes/macrophages in the presence of [6-3H]glucosamine. Radiolabelled viral glycoproteins were isolated from the cell-free supernatants and digested with trypsin. Glycans were sequentially liberated by endo-beta-N-acetylglucosaminidase H and peptide-N4-(N-acetyl-beta-glucosaminyl) asparagine amidase F, and fractionated according to charge and size. Comparison of the oligosaccharide profiles revealed that the envelope glycoproteins of different virus isolates, propagated in the same host cells, yielded very similar glycan patterns, whereas cultivation of an isolate in different host cells resulted in markedly divergent oligosaccharide maps. Variations concerned the proportion of high-mannose-, hybrid- and complex-type substituents, as well as the state of charge and structural parameters of the complex-type species. As a characteristic feature, complex-type glycans of macrophage-derived viral glycoprotein were almost exclusively substituted by lactosamine repeats. Hence, glycosylation of the HIV-2 external envelope glycoprotein seems to be primarily governed by host cell-specific factors rather than by the amino acid sequence of the corresponding polypeptide backbone.

Carbohydrate Sequence↗
PubMed1994

The long-term influence of biotin supplementation on hoof horn quality in horses.

The influence of dietary biotin in horses with brittle hoof horn and chipped hooves was investigated in a long-term study, which was performed over a period from one to six years. 97 horses received 5 mg of biotin per 100 to 150 kg of body weight, per os, daily; 11 horses were not supplemented with biotin and served as controls. The hooves of all horses were evaluated macroscopically every three to four months. Hoof horn specimens of the proximal wall were examined histologically and physically in 25 and 15 horses, respectively. The tensile strength of normal coronary horn was 60 N/mm2 or greater; it was reduced in areas of histological alterations, the lowest value being 20 N/mm2. The hoof horn condition of the biotin-supplemented horses improved after eight to 15 months of supplementation as determined by macroscopic and histologic examinations. The hoof horn condition of most control horses remained constant throughout the study. The growth rate of the coronary horn of horses supplemented with biotin and of control horses was the same. The hoof horn condition deteriorated in 7 of 10 horses after biotin supplementation was reduced or terminated. It was concluded that biotin should be continuously supplemented at the full dosage in horses with severe hoof horn alterations.

Animals↗
PubMed1992

Carbohydrate structure of Marburg virus glycoprotein.

Marburg virus was propagated in E6 cells, a cloned cell line of Vero cells, in the presence of [6-3H]glucosamine. Radiolabelled viral glycoprotein was digested with trypsin, and oligosaccharides were liberated by sequential treatment with endo-beta-N-acetylglucosaminidase H, peptide-N4-(N-acetyl-beta-glucosaminyl)asparagine amidase F and O-glycosidase, by beta-elimination, and by alkaline hydrolysis. After fractionation by HPLC and gel filtration, glycans were characterized chromatographically, by digestion with exoglycosidases and, in part, by methylation analysis and liquid secondary ion mass spectrometry. The oligosaccharide structures thus established include oligomannosidic and hybrid-type N-glycans, as well as neutral fucosylated bi-, tri- and tetraantennary species, most of which carry an additional bisecting N-acetylglucosamine. In addition, high amounts of neutral mucin-type O-glycans with type-1 and type-2 core structures were detected. None of the glycans present in this viral glycoprotein carried sialic acid residues.

Amidohydrolases↗
PubMed1991

Metabolism of metandienone in man: identification and synthesis of conjugated excreted urinary metabolites, determination of excretion rates and gas chromatographic-mass spectrometric identification of bis-hydroxylated metabolites.

After oral administration of metandienone (17 alpha-methyl-androsta-1,4-dien-17 beta-ol-3-one) to male volunteers conjugated metabolites are isolated from urine via XAD-2-adsorption, enzymatic hydrolysis and preparative high-performance liquid chromatography (HPLC). Four conjugated metabolites are identified by gas chromatography-mass spectrometry (GC/MS) with electron impact (EI)-ionization after derivatization with N-methyl-N-trimethyl-silyl-trifluoroacetamide/trimethylsilyl-imidazole (MSTFA/TMS-Imi) and comparison with synthesized reference compounds: 17 alpha-methyl-5 beta-androst-1-en-17 beta-ol-3-one (II), 17 alpha-methyl-5 beta-androst-1-ene-3 alpha,17 beta-diol (III), 17 beta-methyl-5 beta-androst-1-ene-3 alpha,17 alpha-diol (IV) and 17 alpha-methyl-5 beta-androstane-3 alpha,17 beta-diol (V). After administration of 40 mg of metandienone four bis-hydroxy-metabolites--6 beta,12-dihydroxy-metandienone (IX), 6 beta,16 beta-dihydroxy-metandienone (X), 6 beta,16 alpha-dihydroxy-metandienone (XI) and 6 beta,16 beta-dihydroxy-17-epimetandienone (XII)--were detected in the unconjugated fraction. The metabolites III, IV and V are excreted in a comparable amount to the unconjugated excreted metabolites 17-epimetandienone (VI), 6 beta-hydroxy-metandienone (VII) and 6 beta-hydroxy-17-epimetandienone (VIII). Whereas the unconjugated excreted metabolites show maximum excretion rates between 4 and 12 h after administration the conjugated metabolites III, IV and V are excreted with maximum rates between 12 and 34 h.

Administration, Oral↗
PubMed1991

[Fetomaternal transfusion in relation to mode of delivery. Comparison of data from the DFG multicenter study "Rhesus negative" (1965-70) with data from the Freiburg University Gynecologic Clinic (1989)].

Fetomaternal hemorrhage with transfusion of more than 10-25 ml fetal blood into the maternal circulation ("macrotransfusion") is one possible cause of the failure of combined pre- and postpartal anti-D prophylaxis. We analyzed the data from 391 patients who delivered at the UFK Freiburg in 1989. We evaluated the amount of fetomaternal bleeding in different modes of delivery. We observed fetomaternal hemorrhage of clinical relevance in 7.5% of spontaneous delivery, 11.1% of vacuum extraction, 17.7% of cesarean section (p less than 0.05). There was no difference concerning macrotransfusions in the above mentioned modes of delivery. Our data are compared with the data of the DFG multicenter trial "rhesus negative" (1965-79).

Cesarean Section↗
PubMed1991

[Involution and redevelopment of the mammary gland in goats. Histological-histochemical studies after a lactation time of 8-10 months].

7 chamois-coloured mountain goats were used to investigate histologically and histochemically the processes of involution and redevelopment of the mammary gland after a lactation period of 8 to 10 months. Tissue specimens were obtained by incision biopsy at drying-off two months prepartum and afterwards in intervals of 8-16 days up to parturition. The findings of this investigation were compared with results of two former investigations, in which involution and proliferation of the gland were studied separately, thus precluding an overlapping of the two processes. At drying-off, after an 8 to 10 month-lactation, sections indicative of active lactation occurred concomitantly with sections at various stages of involution, as well as early stages of redeveloping alveoli. At 16 days post drying-off, the sections indicating lactation at first examination were in a stage of maximum involution and transformation. Thus, the time required for involution was reduced by half compared to drying-off at peak lactation. At 32 days post drying-off, stages of proliferation predominated with only a few involuting glands. Specimens obtained thereafter contained only redeveloping glands. The histological and histochemical differentiation between areas of involution and those of proliferation may present difficulties during the mid-portion of the dry period. There appears to be an association between the length of the time interval from drying-off to parturition and the rate of tissue transformation in the caprine mammary gland; the rate is increased when the duration of the dry period is reduced.

Animals↗