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Biomedical subjects

R Schmid

Publications and source records attributed to R Schmid.

At least 109 records · Page 6Linked to original sources
PubMed1997

Inhibition of pteridine biosynthesis eliminates blue-light dependent stimulation of red-light saturated photosynthesis in Laminaria saccharina (L.) Lamouroux.

Blue-light stimulation of red light-saturated photosynthetic oxygen evolution in Laminaria saccharina (L.) Lamouroux could be abolished within 5 days by incubation in a solution of 2,4-diamino-6-hydroxypyrimidine (DAHP), an inhibitor of GTP-cyclohydrolase I (E.C.3.5.4.16) activity. Photosynthesis in red light was not detectably affected. GTP-cyclohydrolase I, which catalyses the first step in the biosynthetic pathway of pteridines, was shown to be active in Laminaria. Under conditions that lead to complete inhibition of the photosynthetic stimulation, DAHP reduced the content of the pteridines in the tissue considerably. The amount of pterin was about 14%, that of biopterin was about 45% and that of an unidentified pteridine was about 27% of those of the controls. By contrast, the total concentration of flavins (FAD + FMN - riboflavin) was not significantly affected. The results suggest that pterins may be involved in the response of photosynthesis to blue light, possibly participating in photoreception.

Chromatography, High Pressure Liquid↗
PubMed1997

Ultrastructure of the Corynebacterium glutamicum cell wall.

The cell wall structure of the Gram-positive Corynebacterium glutamicum was evaluated by electron microscopy of thin sections after freeze-substitution and conventional fixation with glutaraldehyde. For the cell wall an overall thickness of approximately 32 nm was determined, with 8.5 nm corresponding to an outer layer, 6.5 nm to an electron translucent region (ETR) as found in mycobacteria and 17 nm to the peptidoglycan. Knob-like surface structures previously observed in freeze-fracture experiments were detected when cells were conventionally processed with a fixation using glutaraldehyde. By mild treatment with detergents approximately 20 proteins were extracted from the cell wall. From seven of these N-terminal amino acid sequences were determined.

Amino Acid Sequence↗
PubMed1997

Mutation (677 C to T) in the methylenetetrahydrofolate reductase gene aggravates hyperhomocysteinemia in hemodialysis patients.

Hyperhomocysteinemia is frequent in hemodialysis patients and represents an independent risk factor for vascular disease in these patients. Elevated total homocysteine (tHcy) plasma levels can results from defective remethylation of Hcy to methionine due to decreased activity of the enzyme methylenetetrahydrofolate reductase (MTHFR). A genetic aberration in the MTHFR gene (677 C to T substitution) has been shown to result in reduced MTHFR activity. We tested the hypothesis that elevation of tHcy plasma levels in hemodialysis patients is influenced by the 677 C to T mutation of the MTHFR gene and examined the relation of the genotype with tHcy, folate and vitamin B12 plasma levels in these patients. The allelic frequency of the MTHFR mutation was evaluated in 203 patients maintained on chronic hemodialysis treatment. Total Hcy, folate, vitamin B12 levels and the MTHFR mutation were analyzed in 69 of the 203 patients and in 69 age- and sex-matched healthy control subjects. The allelic frequency of the 677 C to T transition in the MTHFR gene in hemodialysis patients was 34.7% versus 35.5% in healthy controls. Of 203 patients 26 (12.8%) were homozygous for the mutation (+/+) versus 10.2% in healthy subjects. The heterozygous (+/-) genotype was identified in 43.8% of patients versus 50.7% in controls. The mean tHcy level in hemodialysis patients was 28.7 +/- 11.0 mumol/liter versus 10.0 +/- 3.0 mumol/liter in control subjects. The mean tHcy levels were 36.4 +/- 13.4 mumol/liter in (+/+) patients and 12.2 +/- 4.5 mumol/liter in (+/+) controls, 28.7 +/- 10.8 mumol/liter in (+/-) patients and 9.9 +/- 2.7 mumol/liter in (+/-) controls and 25.4 +/- 8.5 mumol/liter in (-/-) hemodialysis patients versus 9.7 +/- 2.8 mumol/liter in (-/-) controls: There was no significant difference of folate and vitamin B12 concentrations in patients and controls with different MTHFR genotypes. Analysis of covariance including age, gender, folate concentrations, vitamin B12 levels, albumin and creatinine as covariables revealed a significant influence of the (+/+) genotype, albumin and folate status on tHcy levels in hemodialysis patients. Together, our data demonstrate that the extent of hyperhomocysteinemia in hemodialysis patients is not only the result of uremia or folate status, but is also genetically determined by the (+/+) MTHFR genotype. The presence of the 677 C to T mutation in the MTHFR gene does not appear to represent a risk factor for development of end-stage renal disease.

Adult↗
PubMed1997

Inhibition of paracrine angiotensin-converting enzyme in vivo: effects on interstitial glucose and lactate concentrations in human skeletal muscle.

Microdialysis was used to selectively assess the effect of the paracrine renin-angiotensin system (RAS) on interstitial glucose and lactate concentration profiles in skeletal muscle of healthy volunteers (n = 8) during basal and insulin-stimulated conditions. Paracrine RAS was selectively inhibited by local retrodialysis with enalaprilate. Under basal conditions, local administration of enalaprilate (2 micrograms mL-1) increased interstitial dialysate glucose concentration from 0.71 +/- 0.14 mmol L-1 to 0.84 +/- 0.14 mmol L-1 and decreased the serum interstitial gradient (SIGglu) compared with baseline (P < 0.02). Under clamp conditions, enalaprilate, even at the lowest concentration (0.02 microgram mL-1), increased interstitial dialysate glucose concentration from 0.77 +/- 0.11 mmol L-1 to 1.02 +/- 0.09 mmol L-1 and decreased SIGglu compared with baseline (P < 0.01). Interstitial lactate concentrations slightly increased during basal as well as during clamp conditions (P < 0.05 vs. baseline). Selective inhibition of paracrine muscle angiotensin-converting enzyme (ACE) increases interstitial glucose and lactate concentrations and decreases SIGglu in muscle by facilitating transcapillary glucose transport. This effect is more pronounced during hyperinsulinaemia and may be of clinical relevance in diabetic patients treated with therapeutic doses of enalapril.

Adult↗
PubMed1997

Caries and plaque inhibition in rats by five topically applied dentifrices.

The effectiveness of 5 different brands of dentifrices on caries and plaque were tested in rats in 2 experiments. 10 litters of rats each were infected with Streptococcus sobrinus OMZ-176 and Actinomyces viscosus Ny1. The rats were offered the diet 2000a containing either 40% of sucrose (study I) or 10% of sucrose (study II). The following products were tested topically: (1) H2O, (negative control); (2) chlorhexidine diacetate, (positive control); (3) Parodontax NF; (4) Meridol; (5) Colgate Total; (6) Mentadent C; (7) Dent Xpress. Comparisons with the water control in study I showed that plaque extent was decreased by chlorhexidine diacetate, Dent Xpress and by Mentadent C only. All fluoride-containing dentifrices tested reduced caries. In study II, comparisons with the water control showed that plaque extent was reduced by chlorhexidine diacetate, Parodontax, Meridol, Dent Xpress and by Mentadent C. All dentifrices reduced caries, however, the incidence was low. These 2 studies confirm that fluorides incorporated in dentifrices decrease dental caries in the rat. Differences in the effectiveness of caries inhibition between the 5 dentifrices could not be explained either by the form of fluoride utilized or by the antimicrobials added. Rather, the performance of a given dentifrice depended upon the concerted action of the particular ingredients. It appears that the effect of antiplaque agents should be evaluated in the rat model using a diet containing sucrose at a low level.

Actinomyces viscosus↗
PubMed1997

Testosterone-regulated expression of enzymes involved in steroid and aromatic hydrocarbon catabolism in Comamonas testosteroni.

The effect of testosterone as the sole carbon source on protein expression was analyzed in Comamonas testosteroni. Testosterone simultaneously induced the expression of steroid- and aromatic hydrocarbon-catabolizing enzymes and repressed one amino acid-degrading enzyme. It is suggested that steroids play a regulative role in catabolic enzyme synthesis during adaptive growth of C. testosteroni.

Amino Acid Sequence↗
PubMed1997

Expression of a stress- and starvation-induced dps/pexB-homologous gene is controlled by the alternative sigma factor sigmaB in Bacillus subtilis.

SigmaB-dependent general stress proteins (Gsps) of Bacillus subtilis are essential for the development of glucose-starvation-induced cross-resistance to oxidative challenge. However, the proteins directly involved in this nonspecific resistance to oxidative stress have to be identified. We found that one prominent Gsp displayed strong sequence similarity to the previously characterized oxidative-stress-inducible MrgA protein of B. subtilis and to the starvation-induced Dps/PexB protein of Escherichia coli. We therefore designated this prominent Gsp Dps. While MrgA belongs to the peroxide-stress-inducible proteins needed for the H2O2-inducible adaptive response to oxidative stress, Dps belongs to the proteins induced by heat, salt, or ethanol stress and after starvation for glucose but not by a sublethal oxidative challenge. Primer extension experiments identified two overlapping promoters upstream of the coding region of dps, one being sigmaB dependent (PB) and the other being sigmaB independent (P1). Both promoters contribute to the basal level of dps during growth. After stress or during entry into the stationary phase, transcription from PB strongly increased whereas transcription from P1 decreased. Mutant strains lacking Dps completely failed to develop glucose-starvation-induced resistance to oxidative stress. These results confirm our suggestion that sigmaB-dependent general stress proteins of B. subtilis are absolutely required for the development of nonspecific resistance to oxidative stress.

Amino Acid Sequence↗
PubMed1997

Copurification of ribosomal protein S2 and DNA-dependent RNA polymerase from heat-shocked cells of Bacillus subtilis.

The DNA-dependent RNA polymerases from heat-shocked and vegetatively grown cells of Bacillus subtilis were isolated and compared. The RNA polymerase from non-stressed cells had the well known alpha, beta, beta' and sigma composition of eubacterial RNA polymerases. The RNA polymerase from heat-shocked cells exhibited one additional band shown by SDS-PAGE. N-terminal sequencing of the first 16 amino acids of the associated protein demonstrated its identity with the ribosomal protein S2.

Amino Acid Sequence↗
PubMed1997

Laparoscopic anterior extended seromyotomy with posterior truncal vagotomy: an experimental study.

We describe a new laparoscopic modification of parietal cell vagotomy. The laparoscopic anterior extended seromyotomy with posterior truncal vagotomy was performed in five pigs weighing 21 to 25 kg each. Congo-red and pH tests were undertaken 2 weeks later by open gastrotomy. The photographs of the stained gastric mucosa made at the 5-min interval after Congo-red administration were analyzed with a computer-driven area calculation program. Preoperative and postoperative weights were taken for all animals. The experimental parietal cell vagotomy group was compared with the sham group and showed a minimal amount of nondenervated parietal cell mass (0.9 +/- 0.4% versus 28.2 +/- 3.9%, p < 0.05). The pH values showed an inhibition of gastric acid secretion (7.8 +/- 0.7 versus 2.2 +/- 0.4, p < 0.05). During postoperative follow-up, no significant difference in the weight increase of the experimental and the sham control group was noticed (1.6 +/- 0.6 kg versus 2.0 +/- 0.1 kg, p < 0.27). The laparoscopic anterior extended seromyotomy with posterior truncal vagotomy efficiently suppresses gastric acid secretion, preserving the motility of the antrum and pylorus and diminishing the risk of residual areas of innervation. This procedure avoids dissection of the esophagus and can provide an easier but equally effective operative treatment of ulcer disease compared with other types of parietal cell vagotomy.

Animals↗
PubMed1997

Sensitive bioaffinity assays with individual microparticles and time-resolved fluorometry.

Future immunoassays and nucleic acid hybridization assays will be performed in miniaturized formats that utilize microchips or microparticles. This will require a sensitive detection technology that allows spatial resolution. By using fluorescent europium chelates and time-resolved microfluorometry, one can detect 11,000 europium molecules on individual microparticles. In a miniaturized noncompetitive immunoassay of prostate-specific antigen (PSA), we quantitatively detected 5 ng/L (0.05 amol per particle) of the analyte on an individual microparticle with excellent precision over the whole measurement range (CV <10%). Using a hybridization assay, we also could detect the deltaF508 mutation for cystic fibrosis on individual microparticles. Consequently, fluorescent lanthanide chelate labels and time-resolved microfluorometry qualify as the next generation of technology in this field.

Chelating Agents↗
PubMed1996

[Sudden vertigo--differential diagnosis and therapy in peripheral vestibular (inner ear-induced) forms].

The most important forms of inner ear disorders manifesting as sudden vertigo may be distinguished by the duration of the vertiginous spells: sudden vertigo, diminishing during days = acute peripheral vestibulopathy, recurrent spells lasting for hours = Ménière's disease, recurrent vertigo lasting for minutes = "vascular', recurrent positioning-induced vertigo lasting for seconds = benign paroxysmal positioning vertigo (BPPV). In the last years, major progress was made in the treatment of BPPV. Based on new ideas on the underlying pathomechanism, this most common form of vestibular vertigo now can be treated definitively in most patients within a few minutes by a simple maneuver (canalith reposition maneuver by Epley/Parnes). This procedure is presented in this paper.

Acute Disease↗
PubMed1996

[Cost reduction in long-term nursing thanks to a memory clinic--results of a case control study].

Between 1991 and 1995, 334 persons from the city of Zurich have been investigated at the gerontologic counselling facility of the memory clinic of the nursing home Entlisberg near Zurich. 49 (14.7%) of these persons suffered from a treatable disease (16 from depression, 13 from chronic intoxication, 20 from other treatable diseases), 10 from other disturbances (debility or postapoplectic state), and 275 from dementia. In 45% of the cases dementia was moderate, in 47% moderate to severe, and in 8% severe. In most cases dementia was of Alzheimer's type (60.7%), others were of multi-infarct type (17.5%), of mixed type (13.1%), or other types (8.7%). Until march 1996, 64 (19.4%) of these 334 on the average 74-year-old persons treated in the memory clinic have been admitted to a city nursing home. They have compared to a random sample, including 312 demented persons of similar ages and similar date of admittance to the same institutions. The proportion of demented persons cared before admittance by a spouse was about 28% in both groups. On an average, the mini mental state (Zurich variant) at admittance to a nursing home was 10.95 points in patients from the memory clinic, compared to 13.43 points in the control group. Thus, patients that have formerly been advised and trained entered the nursing home in a state of dementia more advanced by 2.48 points. Based on an average yearly demelioration by about 2.4 points, this means admittance to a nursing home is delayed by 376 days. Patients for whom admittance to a nursing home could be avoided completely by the treatment proposed by the counselling were not considered in this calculation.

Aged↗
PubMed1996

Purification and partial sequencing of high-affinity progesterone-binding site(s) from porcine liver membranes.

High-affinity progesterone-binding sites have been identified, characterized in and purified from porcine liver membranes. They were functionally solubilized by the non-denaturing zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid (Chaps, 20 mM. detergent/protein mass ratio 4:1) at a yield of 75-80%. Using [3H]progesterone as radioligand, binding studies showed high-affinity and low-affinity binding sites in microsomal preparations with an apparent Kd2 of 11 nM and an apparent Kd2 of 286 nM. In solubilized fractions the high-affinity binding sites were present at an apparent Kd2 of 69 nM. In both preparations, progesterone binding was time-dependent, saturable, reversible, and showed a similar hierachy of affinities for related steroids. A purification scheme was developed based on anion-exchanger procedures. The purified fraction as identified by maximum specific progester-one-binding activity contained two major polypeptides of apparent molecular masses (SDS/PAGE) of 28 kDa and 56 kDa, respectively. Sequencing of both polypeptides showed an identical amino terminus without significant identity in the amino acid sequence to any known protein primary structure.

Amino Acid Sequence↗
PubMed1996

Polycyclic aromatic hydrocarbons in Norwegian forest soils: impact of long range atmospheric transport.

Levels of nine selected polycyclic aromatic hydrocarbons, PAHs, in surface soils from areas in southern and central Norway are presented. Levels in central Norway are generally low, while the southern Norway soils are about ten-fold higher with respect to 4 and 5 ring PAHs. Comparison with air quality data indicates long-range atmospheric transport to be the major source of the excess 4 and 5 ring PAHs in the south. Analyses of peat cores from ombrotrophic bogs support this assumption, and these provide a potentially useful approach for temporal studies of atmospheric PAH deposition. Analytical data for naphthalene in soils depend very much on the sampling and storage of the samples before analysis.

Journal Article↗
PubMed1996

After antagonization of acute opiate overdose: a survey at hospitals in Vienna.

This study describes the clinical management and characteristics of people who, following acute opioid overdose, are taken to hospital after efficient antagonization by the pre-hospital emergency service. In addition, it defines areas of interest for further research. Over a 4-month period (September-December 1993) we collected data by a structured protocol sheet on patients' characteristics, anamnestic data on abuse and emergencies, clinical presentation, treatment by specific antidote and routine laboratory investigations. Outcome was verified by retrospective review of prehospital and forensic data. We studied 77 subjects, predominantly young males, who were involved in 83 emergencies, mostly occurring at weekends. In more than 60% of cases a single administration of specific antidote sufficed to stabilize the patients; 64% of patients left hospital against medical advice after an average stay of less than 6 hours; 46% denied daily opioid abuse and half the subjects, especially younger drug-users, seemed interested in counselling. This hospital-based study did not provide reliable data on the epidemiology of opioid overdose. Clinical management is determined by experience, pragmatism and beliefs. Efforts towards secondary prevention of drug problems at emergency departments might be warranted, and further research on pattern and management of opioid overdose is needed.

Adolescent↗
PubMed1996

Medical education in the former Soviet Union.

After World War I, medical education in the Soviet Union and medical education in the United States headed in strikingly divergent directions. In keeping with the recommendations of the Flexner report, medical education in the United States became a university-based academic discipline based in the natural sciences. In contrast, the Soviet Union created a series of free-standing medical institutes whose admission, curricular, and pedagogic policies were centrally controlled in strict conformity with political doctrine. Notable features of the Soviet system were narrowly defined professional education; early specialization, beginning in the first year of medical school; and emphasis on empirical clinical training at the expense of scientifically based education. Despite the historical differences between Soviet and American medical education, there are several issues that face present-day medical educators in both the United States and the Soviet successor states. These include an overabundance of specialists, the need to provide equitable professional opportunities for physicians of both sexes, and the need to provide access to medical education for qualified candidates from underrepresented social or ethnic groups or from geographically remote regions.

Academic Medical Centers↗
PubMed1996

Cold shock stress-induced proteins in Bacillus subtilis.

Bacteria respond to a decrease in temperature with the induction of proteins that are classified as cold-induced proteins (CIPs). Using two-dimensional gel electrophoresis, we analyzed the cold shock response in Bacillus subtilis. After a shift from 37 to 15 degrees C the synthesis of a majority of proteins was repressed; in contrast, 37 proteins were synthesized at rates higher than preshift rates. One hour after cold shock, the induction of CIPs decreased, and after 2 h, general protein synthesis resumed. The identified main CIPs were excised from two-dimensional gels and were subjected to microsequencing. Three small acidic proteins that showed the highest relative induction after cold shock were highly homologous and belonged to a protein family of which one member, the major cold shock protein, CspB, has previously been characterized. Two-dimensional gel analyses of a cspB null mutant revealed that CspB affects the level of induction of several CIPs. Other identified CIPs function at various levels of cellular physiology, such as chemotaxis (CheY), sugar uptake (Hpr), translation (ribosomal proteins S6 and L7/L12), protein folding (PPiB), and general metabolism (CysK, Ilvc, Gap, and triosephosphate isomerase).

Bacillus subtilis↗