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Biomedical subjects

R Schubert

Publications and source records attributed to R Schubert.

At least 163 records · Page 9Linked to original sources
PubMed1983

Measurement of bile acid kinetics in human serum using stable isotope labeled chenodeoxycholic acid and capillary gas chromatography electron impact mass spectrometry.

A non invasive method for measurement of bile acid kinetics in serum using (24-13C)chenodeoxycholic acid has been developed. After oral administration of 50 mg (24-13C)chenodeoxycholic acid, the exponential decay of the 13C atom percent excess was measured in serum using capillary gas chromatography mass spectrometry. This required that isotope ratios were measured with high accuracy and coefficients of variation less than 1% by means of selected ion monitoring and scan averaging. The clinical applicability was tested by repeated determination of pool size, fractional turnover and synthesis rate of chenodeoxycholic acid in one healthy volunteer. This method permitted the determination of pool size, synthesis and conversion of chenodeoxycholic acid into lithocholic acid in man without the use of radioactive tracers and without repeated duodenal intubation.

Bile Acids and Salts↗
PubMed1983

Lung metastasis of a meningioma.

UNLABELLED: Case report of a 35-year-old male patient. 1976: operation for a falx-meningioma. 1981: meningioma recurrence and further intracranial meningiomas. HISTOLOGY: 1976 and 1981 endotheliomatous meningioma: no signs of malignancy. Prior to the 2nd operation in 1981 a lung tumor was diagnosed for the first time. HISTOLOGY of the lung tumor: endotheliomatous meningioma, same histology as in cerebral meningiomas.

Adult↗
PubMed1983

Studies on the mechanism of bile salt-induced liposomal membrane damage.

The damage of phosphatidylcholine membranes by bile salts such as cholate, deoxycholate (DC), chenodeoxycholate (CDC), ursodeoxycholate (UDC), as well as their glyco- and tauroconjugates, and lithocholate (LC) were studied. The permeabilities of liposomes differing in size (700 and 1,700 A in diameter) were determined at increasing bile salt concentrations. The release of entrapped raffinose (3H) (MW: 594) or inulin (3H) (MW: 5,000) was measured by pelleting of the liposomes and subsequent determination of the radioactivities in the supernatant. The release of these uncharged volume markers of different size points to a formation of membrane leaks increasing in size with increasing bile salt concentration. Determination of the membrane damaging threshold concentrations of bile salts demonstrated a higher stability of the smaller liposomes. Incubation of the smaller liposomes with increasing DC concentrations results in a successive substitution of lecithin by DC. The predominantly DC-containing vesicles are of remarkable stability against higher DC concentrations. The damaging properties of bile salts increase with decreasing number of hydroxy groups, with the exception of UDC and its conjugates which are much less membrane toxic than the other dihydroxy bile salts. Conjugation with glycine or taurine slightly enhances the membrane toxicity of bile salts with the exception of UDC. Sulfation of the 3-alpha-hydroxy group of LC reduces the damaging effect to about 10%.

Animals↗
PubMed1982

[A sensitive method for the analysis of the glycosaminoglycan distribution pattern, applied to 9 intervertebral discs of one human spine].

A method has been established for analysing the glycosaminoglycan distribution pattern in small specimens from intervertebral discs and other connective tissue materials. The procedure is based on the consecutive digestion by the specific enzymes hyaluronate lyase, chondroitin sulfate lyase AC and ABC. The quantitative determination of the resulting disaccharides was achieved by high performance liquid chromatography with a detection limit of less than 0.1 nmmol. The undigested heparan- and keratansulfate were separated from each other by thin layer chromatography and quantified by the colorimetric determination of uronic acid and hexosamine, respectively. Correlation of distribution patterns obtained by this method with those obtained by ion exchange chromatography (Dowex 1 X 2) is not possible without the additional enzymatic characterization of the ion exchange chromatographic fractions. The method was applied to 9 discs of one human spine (anulus fibrosus and nucleus pulposus separately) with the following results: 1) there were no systematic changes to be seen in the distribution patterns with respect to the location of the discs in the spine, and 2) the galactosaminoglycan/keratansulfate ratio was higher in the anulus fibrosus than in the nucleus pulposus.

Adult↗
PubMed1981

Effects of severe arterial hypocapnia on regional blood flow regulation, tissue PO2 and metabolism in the brain cortex of cats.

The effect of a stepwise decrease in PaCO2 from 3.9-1.6 kPa on rCBF, rCMRO2, tissue PO2 and concentrations of glucose, lactate, pyruvate, ATP, ADP, AMP and phosphocreatine in the brain cortex was studied in cats lightly anaesthetized with sodium pentobarbital. 1. Moderate lowering of PaCO2 to 2.5 kPa induced in all animals a homogeneous decrease of rCBF in corresponding areas of the right and left hemisphere. Mean rCBF fell from 129.2 to 103.1 ml X 100 g-1 X min-1, while rCMRO2 remained unchanged (12.7-12.9 ml X 100 g-1 X min-1). The tissue PO2 frequency histograms showed a shift to lower values without indicating the presence of brain tissue hypoxia. 2. Severe arterial hypocapnia (PaCO2 = 1.6 kPa) caused an inhomogeneous blood flow reaction. Both further decreased as well as increased rCBF values were measured simultaneously in the brain cortex of individual animals (mean rCBF = 97.6 ml X 100 g-1 X min-1). At the same time tissue PO2 measurements and metabolite assays indicated the presence of pronounced brain tissue hypoxia. The tissue concentrations of lactate and pyruvate and the lactate/pyruvate ratio were significantly increased, while the phosphocreatine concentration was significantly reduced. In addition, rCMRO2 decreased to 11.3 ml X 100 g-1 X min-1. The results provide conclusive evidence that severe arterial hypocapnia leads to an insufficient O2 supply of the brain cortex, which in turn seems to counteract the influence of hypocapnia on cortical blood flow regulation.

Adenine Nucleotides↗
PubMed1980

[On the reactivation of atrophic oral mucosa through topical application of 17 beta-estradiol (author's transl)].

Dental plastics are capable of absorbing therapeutically effective amounts of estrogens and giving them off continuously for a period of several months. Kallocryl C enriched with 17 beta-estradiol has the effect of triggering keratinization of atrophic oral mucosa of the dentural support. There is no fear of this form of application leading to hyperkeratosis. Subjective complaints such as, for example, oral mucosal burning are either alleviated or eliminated. Hormonal side effects have not been observed.

Aged↗