Search PubMed⌕ Search

Biomedical subjects

A Weber

Publications and source records attributed to A Weber.

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

New ways of determining structural groups in brown coals and their bioconversion products by FT IR spectroscopy.

New methods of determining the structural groups -COOH and -CH2- have been developed. The investigation of carboxyl groups is possible both after derivatization with p-fluorophenacylbromide and by quantitative interpretation of the Fourier transform infrared (FT IR) spectra. There exists a linear relationship between the results of these two methods that is generally valid for the analysis of all brown coal components. The maximum extinction coefficient of the symmetric stretching vibration band of the CH2 groups has been determined using model substances. This allows quantification of this structural group directly from the FT IR spectrum. The results agree with the contents of methylene groups as determined by 13C-cross polarization-magic angle spinning nuclear magnetic resonance (13C CPMAS NMR) spectroscopy. Using these methods, the COOH and CH2 groups contained in brown coals of the North Rhine region and in their bioconversion products have been quantified.

Biodegradation, Environmental↗
PubMed2000

[Effect of portal branch ligation on liver regeneration in the rat].

GOAL: The aim of this study was to assess liver regeneration after partial portal ligation. METHODS: 70% partial portal occlusion was obtained by ligation of the left portal vein branch. Total liver weight ratio were measured 96 hours after partial portal occlusion and in sham operated animals. The kinetics of hepatocytes division was evaluated by measuring the incorporation of 5-bromo-21-deoxyuridine into replicating cells at various time points by immunohistochemistry. RESULTS: Partial portal occlusion did not alter the total liver weight 96 hours after surgery. It resulted in atrophy of the ligated lobes and hypertrophy of the lobes with preserved portal flow. Hypertrophy was associated to an increase of the percentage of replicating hepatocytes. The replication rate was maximum at 28 hours with a peak at 12.5% and was prolonged beyond the 48th hour. CONCLUSIONS: Partial portal occlusion results in major and prolonged regeneration process in the liver lobes with preserved portal flow.

Animals↗
PubMed2000

Investigation of human infections with verocytotoxin-producing strains of Escherichia coli (VTEC) belonging to serogroup O118 with evidence for zoonotic transmission.

Twenty verocytotoxigenic Escherichia coli (VTEC) O118 strains isolated between 1996 and 1998 from human patients in Germany were analysed for their serotypes, their virulence markers and their epidemiological relatedness. Three strains were typed as O118:H12, these carried only the VT2d-Ount variant gene and were not associated with diarrhoea or haemolytic uraemic syndrome (HUS). Seventeen strains were serotyped as O118:H16 or O118:non-motile (NM). These carried all the genes for VTI, eae and EHEC-haemolysin. The O118:H16/NM strains were from diarrhoea (13 cases) and HUS (2 cases). Sixteen of the patients were young infants and most infections were associated with a rural environment. Evidence for zoonotic transmission from cattle to humans was found in two cases. The epidemiological relationship between the human and bovine O118:H16/NM isolates was indicated by homogeneous plasmid patterns and by very similar XbaI restriction patterns obtained by pulsed-field gel electrophoresis. VTEC O118:H16/NM are emerging pathogens in Germany and should be classified as new enterohaemorrhagic E. coli (EHEC) types.

Adolescent↗
PubMed2000

Trend, seasonal and multivariate modelling study of wet precipitation data from the Austrian Monitoring Network (1990-1997).

The aim of the present study was to analyse the data structure of a large data set from rainwater samples collected during a long-term interval (1990-1997) by the Austrian Precipitation Monitoring Network. Eleven sampling sites from the network were chosen as data sources (chemical concentrations of major ions only) covering various location characteristics (height above sea level, rural and urban sampling positions, Alpine rim and Alpine valley disposition, etc.). The analytical results were treated by the application of already classical environmetric approaches, such as linear regression analysis, time-series analysis and principal components analysis (PCA). For most of the sampling sites, a distinct trend of acidity decrease of the wet precipitation was observed. An overall decrease in sulfate concentration for the whole period and all sites of 3.9% year(-1) (2.0 muequiv. L(-1) year(-1)) was found. The free acidity decrease for most of the sites was between 3.5 and 10.9% year(-1). No significant linear trends were found for nitrate. Base cations either decreased (mean percentage decrease for calcium was 5.4% year(-1) and for magnesium 4.4% year(-1)) or did not show any significant change (sodium, potassium). The overall decrease in ammonium concentration was 2.3% year(-1). Further, some typical "rural" (summer minima and winter maxima) and "urban" (winter minima and spring maxima) seasonal behaviour for the majority of the sites in consideration could be defined, indicating the influence of local emission sources. Several latent factors, named "anthropogenic", "crustal" and "mixed salt", were revealed by the multivariate modelling procedure (PCA) possessing a similar structure for most of the sites. The unavoidable exceptions observed were indications of the influence of sporadic local events (construction and agricultural activities, secondary emission sources, etc.), and an effort was made to explain these exceptions.

Acid Rain↗
PubMed2000

Plastidic metabolite transporters and their physiological functions in the inducible crassulacean acid metabolism plant Mesembryanthemum crystallinum.

The inducible crassulacean acid metabolism (CAM) plant Mesembryanthemum crystallinum accumulates malic acid during the night and converts it to starch during the day via a pathway that, because it is located in different subcellular compartments, depends on specific metabolite transport across membranes. The chloroplast glucose transporter (pGlcT) and three members of the phosphate translocator (PT) family were isolated. After induction of CAM, transcript amounts of the phosphoenolpyruvate (PEP) phosphate translocator (PPT) and the glucose-6-phosphate (Glc6P) phosphate translocator (GPT) genes were increased drastically, while triose phosphate (TP) phosphate translocator (TPT) and the pGlcT transcripts remained unchanged. PPT- and GPT-specific transcripts and transporter activities exhibited a pronounced diurnal variation, displaying the highest amplitude in the light. pGlcT transcripts were elevated towards the end of the light period and at the beginning of the dark period. These findings, combined with diurnal variations of enzyme activities and metabolite contents, helped to elucidate the roles of the PPT, GPT, TPT and pGlcT in CAM. The main function of the PPT is the daytime export from the stroma of PEP generated by pyruvate orthophosphate:dikinase (PPDK). The increased transport activity of GPT in the light suggests a higher requirement for Glc6P import for starch synthesis rather than starch mobilization. Most likely, Glc6P rather than 3-phosphoglycerate or triose phosphates is the main substrate for daytime starch biosynthesis in M. crystallinum plants in which CAM has been induced (CAM-induced), similar to non-green plastids. In the dark, starch is mobilized both phosphorylytically and amylolytically and the products are exported by the GPT, TPT and pGlcT. The transport activities of all three phosphate translocators and the transcript amounts of the pGlcT adapt to changing transport requirements in order to maintain high metabolic fluxes during the diurnal CAM cycle.

Biological Transport, Active↗
PubMed2000

'Microsmatic' primates revisited: olfactory sensitivity in the squirrel monkey.

Using a conditioning paradigm, the olfactory sensitivity of three squirrel monkeys to nine odorants representing different chemical classes as well as members of a homologous series of substances was investigated. The animals significantly discriminated dilutions as low as 1:10,000 n-propionic acid, 1:30,000 n-butanoic acid and n-pentanoic acid, 1:100,000 n-hexanoic acid, 1:1Mio n-heptanoic acid, 1:30, 000 1-pentanol, 1:300,000 1,8-cineole, 1:1Mio n-heptanal and 1:30Mio amyl acetate from the near-odorless solvent, with single individuals scoring even slightly better. The results showed (i) the squirrel monkey to have an unexpectedly high olfactory sensitivity, which for some substances matches or even is better than that of species such as the rat or the dog, and (ii) a significant negative correlation between perceptibility in terms of olfactory detection thresholds and carbon chain length of carboxylic acids. These findings support the assumptions that olfaction may play a significant and hitherto underestimated role in the regulation of primate behavior, and that the concept of primates as primarily visual and 'microsmatic' animals needs to be revised.

Aldehydes↗
PubMed2000

Burnout syndrome: a disease of modern societies?

In the light of social change and a transformation in the work situation, interest in the problem of burnout has grown over the past decade. There is a conspicuous discrepancy, however, between what is regarded as certain knowledge and what is published opinion. To date, there is no generally accepted definition of burnout, or binding diagnostic criteria. According to the most common description at present, burnout syndrome is characterized by exhaustion, depersonalization and reduced satisfaction in performance. Because of its aetiopathogenesis, burnout is today mainly regarded as the result of chronic stress which has not been successfully dealt with. This paper gives an overview of the current definition for burnout syndrome and states possible contemporary hypotheses for its aetiology. By examining diagnostic criteria and possible therapies, methods of prevention are discussed. There is an urgent need for further investigations to determine whether burnout syndrome is a work-related disease.

Antidepressive Agents↗
PubMed2000

A comparison of intrathecal analgesia with fentanyl or sufentanil after total hip replacement.

UNLABELLED: We designed this study to compare the postoperative analgesic effects of intrathecal fentanyl and sufentanil, the end points being onset, quality, and duration of action. A total of 42 geriatric patients, scheduled for elective total hip replacement under continuous spinal anesthesia, were randomized in two double-blinded groups as soon as they experienced a pain score higher than 3 of 10 on the visual analog scale in the recovery room. Either 7.5 microg sufentanil or 40 microg fentanyl in 2 mL normal saline were intrathecally administered. Pain scores, rescue analgesia (ketorolac and morphine), and adverse effects (respiratory depression, postoperative nausea and vomiting, and itching) were recorded for 24 h after surgery. In both groups, comparing sufentanil to fentanyl, the time to a pain score <3 (9 +/- 9 vs 11 +/- 8 min), the time to the lowest pain score (18 +/- 6 vs 20 +/- 15 min), and the time to the first systemic analgesic intervention for a pain score >3 (241 +/- 102 vs 214 +/- 120 min) were comparable as were the analgesic requirements during the first 24 h. We conclude that, after total hip replacement, both lipid soluble opioids produce excellent analgesia with comparable onset, duration of action, and low incidence of minor adverse effects. IMPLICATIONS: We compared the postoperative analgesic properties of 40 microg intrathecal fentanyl and 7.5 microg sufentanil after total hip replacement. Both opioids provided satisfactory analgesia, with comparable onset (11 +/- 8 vs 9 +/- 9 min) and duration of action (214 +/- 120 vs 241 +/- 102 min), as well as low incidence of minor side effects.

Aged↗
PubMed2000

Identification, purification, and molecular cloning of a putative plastidic glucose translocator.

During photosynthesis, part of the fixed carbon is directed into the synthesis of transitory starch, which serves as an intermediate carbon storage facility in chloroplasts. This transitory starch is mobilized during the night. Increasing evidence indicates that the main route of starch breakdown proceeds by way of hydrolytic enzymes and results in glucose formation. This pathway requires a glucose translocator to mediate the export of glucose from the chloroplasts. We have reexamined the kinetic properties of the plastidic glucose translocator and, using a differential labeling procedure, have identified the glucose translocator as a component of the inner envelope membrane. Peptide sequence information derived from this protein was used to isolate cDNA clones encoding a putative plastidic glucose translocator from spinach, potato, tobacco, Arabidopsis, and maize. We also present the molecular characterization of a candidate for a hexose transporter of the plastid envelope membrane. This transporter, initially characterized more than 20 years ago, is closely related to the mammalian glucose transporter GLUT family and differs from all other plant hexose transporters that have been characterized to date.

Amino Acid Sequence↗
PubMed2000

Pilus-mediated adherence of Haemophilus influenzae to human respiratory mucins.

Haemophilus influenzae, especially the nontypeable strains, are among the most common pathogens encountered in patients with chronic lung disease and otitis media. We and others have demonstrated that respiratory isolates of nontypeable H. influenzae bind to human mucins, but the mechanism of binding is not entirely clear. We have therefore examined the role of pili in the adherence of both type b and nontypeable H. influenzae to human respiratory mucins. We used isogenic H. influenzae strains with a mutation in the structural gene for pilin (hifA), a laboratory H. influenzae strain transformed with a type b pilus gene cluster (from strain C54), antibodies raised against H. influenzae HifA, and Escherichia coli strains carrying a cloned type b pilus gene cluster (from strain AM30) in these studies. All bacteria lacking HifA or the pilus gene cluster had decreased adherence of piliated H. influenzae to mucins, and Fab fragments of anti-HifA antibodies inhibited the adherence. E. coli strains carrying the cloned type b pilus gene cluster were six to seven times more adhesive than strains carrying the vector. The role of other putative adhesins was not examined and thus cannot be excluded, but these studies support a role for pili in the binding of H. influenzae to human respiratory mucins.

Antibodies, Bacterial↗
PubMed2000

Enterohemorrhagic Escherichia coli (EHEC) strains of serogroup O118 display three distinctive clonal groups of EHEC pathogens.

A recent case report of a child infected with enterohemorrhagic Escherichia coli (EHEC) of serotype O118:H16 in Bavaria, in association with the isolation of a bovine O118 strain on the same farm (A. Weber, H. Klie, H. Richter, P. Gallien, M. Timm, and K. W. Perlberg, Berl. Muench. Tieraerztl. Wochenschr. 110:211-213, 1997), prompted us to investigate the relationship between bovine and human strains of serogroup O118. A total of 29 human O118 E. coli strains from Europe (21), Canada (4), and Peru (4) were compared by virulence typing and macrorestriction analysis with 7 bovine O118 EHEC strains isolated in Bavaria. Twenty-five of the human strains were characterized as EHEC. By serotyping and determination of the virulence-associated factors Shiga toxin (stx1 stx2 stx2 variants), intimin (eae), and EHEC hemolysin (Hly(EHEC)), three distinctive groups of O118 human pathogens were identified. Most of the strains belonged to serotype O118:H16, displaying the virulence traits Stx1, intimin, Hly(EHEC), and EspP/PssA (group 1). In addition, we identified strains of serotype O118:H12 (Stx2d only; group 2) and of serotype O118:H30 (Stx2 and intimin; group 3). Macrorestriction analysis with BlnI and XbaI revealed that all strains with a single O118 serotype profile (O118:H12, O118:H16, and O118:H30) belonged to one clonal cluster, irrespective of their origin. Group 1 strains clustered in the same clonal group as the bovine O118:H16 strains. Moreover, four pairs of strains of different origins and indistinguishable by all other methods applied were identified as group 1 strains. Our data support the direct transmission of an EHEC O118:H16 strain from a calf to a 2-year-old boy in the above-mentioned case report. Since bovine and human O118:H16 strains represent the same clones, they must be considered zoonotic EHEC pathogens. In contrast, EHEC strains of serotypes O118:H12 and O118:H30 have been isolated only from humans, indicating a reservoir for certain human O118 EHEC strains other than bovines.

Adhesins, Bacterial↗
PubMed2000

Expression of human alpha-defensin 5 (HD5) mRNA in nasal and bronchial epithelial cells.

BACKGROUND/AIMS: Human defensins are antibiotic peptides expressed in myeloid and epithelial cells. Human alpha-defensin 5 (HD5) has been detected in Paneth cell granules in the crypts of Lieberkühn and has recently been identified in the female reproductive tract. The aim of this study was to investigate the presence of HD5 mRNA in nasal and bronchial epithelial cells. METHODS/RESULTS: Semiquantitative reverse transcription polymerase chain reaction (RT-PCR) analysis showed that HD5 mRNA was expressed infrequently and to varying degrees in bronchial and nasal epithelial cells. In situ hybridisation resulted in a positive signal in the epithelial layer of nasal polyps. HD5 mRNA was locally restricted to a specific area of epithelial cells and also occurred in submucosal glands. CONCLUSIONS: HD5 mRNA expression in nasal and bronchial epithelial cells is rare and seemed to be locally induced. The results indicate that HD5 might play a role in innate defence in nasal and bronchial epithelia.

Base Sequence↗
PubMed2000

[Mycozoonoses with special regard to ringworm of cattle].

Ringworm of cattle is nearly exclusively caused by Trichophyton verrucosum. This skin disease is worldwide present in cattle and is responsible for high economic losses in cattle farming. T. verrucosum may also be responsible for severe skin diseases in man. For economic and epidemiological causes a control of ringworm in cattle is still necessary. Preventive measures consist in hygiene and vaccination of cattle with live vaccines against ringworm in cattle.

Animals↗
PubMed1999

Tropomodulin increases the critical concentration of barbed end-capped actin filaments by converting ADP.P(i)-actin to ADP-actin at all pointed filament ends.

The pointed end capping protein, tropomodulin, increases the critical concentration of barbed end capped actin, i.e. it lowers the apparent affinity of pointed ends for actin monomers. We show here that this is due to the conversion of pointed end ADP. P(i)-actin (low critical concentration) to ADP-actin (high critical concentration) when 70-98% of the ends are capped by tropomodulin. We propose that this is due to the low affinity of tropomodulin for pointed ends (K(d) approximately 0.3 microM), which allows tropomodulin to rapidly exchange binding sites and transiently block access of actin monomers to all pointed ends. This leaves time for ATP hydrolysis and phosphate release to go to completion between successive monomer additions to the pointed end. When the affinity of tropomodulin for pointed ends was increased about 1000-fold by the presence of tropomyosin (K(d) < 0.05 nM), capping of 95% of the ends by tropomodulin did not alter the critical concentration. However, the critical concentration did increase when the tropomodulin concentration was raised to the high values effective in the absence of tropomyosin. This may reflect transient tropomodulin binding to tropomyosin-free actin molecules at the pointed ends of the tropomyosin-actin filaments without a high affinity tropomodulin cap, i.e. the ends that determine the value of the actin critical concentration.

Actins↗
PubMed1999

Spinach hexokinase I is located in the outer envelope membrane of plastids.

The subcellular localization of hexokinase activities in plant cells has been a matter of debate for a long time. We have isolated a hexokinase cDNA fragment from glucose-fed spinach leaves using a differential display reverse transcription-PCR approach. The corresponding cDNA was expressed in Escherichia coli and an antiserum, raised against the recombinant protein, was used in subcellular localization studies. The spinach hexokinase could be localized primarily to the outer envelope membrane of chloroplasts where it is inserted via its N-terminal membrane anchor. We suggest that the chloroplast envelope hexokinase is involved in the energization of glucose export from plastids rather than in the sugar-sensing pathway of the plant cell.

Base Sequence↗
PubMed1999

[Immunoglobulin subclass defects in patients with therapy refractor chronic rhinosinusitis].

In the present study 220 patients suffering from recurrent rhinosinusitis and not responding to antibiotic treatment were evaluated for a defect in IgG-immunoglobulin subclasses. Twenty-one of these patients were found to have an antibody deficiency. These included deficiencies of IgG-2 (n = 10), IgG-1 (n = 6), IgG-3 (n = 1) and IgG-4 (n = 1). A common variable immune disease was diagnosed in three patients that was characterized by an additional defect in the IgG main class. However, an IgG subclass deficiency can only be ascertained by an immunological evaluation. The significance of a deficiency can be identified by a reaction to vaccination using (for example) protein or polysaccharide antigens. Treatment consists of antibiotics, intravenous immunoglobulins and long-term follow-up. Endonasal microsurgery should only be performed in cases that do not respond to conservative treatment. It is particularly necessary to observe these patients because a deficiency of immunoglobulin subclass in certain cases is the first sign of an immunological impairment that can advance to a severe immunodeficiency and predispose to the development of malignancy.

Adolescent↗