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Biomedical subjects

G Schenk

Publications and source records attributed to G Schenk.

At least 37 records · Page 2Linked to original sources
PubMed1991

[MRT of orofacial tumors--initial clinical experiences with turbo-flash intensity studies].

We examined 36 patients with carcinomas of the tongue and the floor of the mouth. In 11 cases, a clear definition of the tumor extent was not possible using T2 w. spin echo sequences and T1 w. spin echo and gradient echo sequences after injection of contrast material. This delineation was attained with Turbo-FLASH intensity-vs-time studies (Gad-DTPA). The time of acquisition of each measurement was about 1 sec. At the end of injection of Gad-DTPA, 30 measurements with a delay of 1 sec between two measurements were performed. Using this technique, a marginal zone at the boundary of the tumor of very high signal intensity was visible within first minute after Gadolinium injection. This method is not required in the case of clearly hypointense (majority of the tumors) or hyperintense (minority) lesions on T1 w. Gadolinium-enhanced SE or GE images.

Aged↗
PubMed1989

Methotrexate serum-level determinations during low-dose therapy of rheumatoid and psoriatic arthritis.

In 29 patients, 21 suffering from psoriatic arthritis and eight patients suffering from rheumatoid arthritis, methotrexate serum-levels were determined by means of radioimmunoassay. The aim of the investigation was to recognize an eventual dependence of the serum level of methotrexate on the total cumulative dose and to test the possibility of a concomitant therapy control. Beside the determinations of the serum levels of methotrexate, clinical examinations and laboratory tests were done at regular intervals. The values obtained showed no significant increase during the course of therapy compared to the values at the beginning of the treatment. Likewise no correlation to the total cumulative dose, the clinical picture or to the occurrence of side-effects could be found. Nor could any relationship between the changing of laboratory parameters and the methotrexate serum-levels be observed. No differences appeared in the methotrexate serum-levels during therapy of either rheumatoid or psoriatic arthritis patients. In conclusion it seems impossible to monitor a low-dose methotrexate therapy by continuous determinations of the serum levels of the drug.

Arthritis, Rheumatoid↗
PubMed1989

Metabolism of the calcium antagonist gallopamil in man.

The metabolism of gallopamil (5-[(3,4-dimethoxyphenyl)methylamino]-2-(3,4,5-trimethoxyphenyl) -2- isopropylvaleronitrile hydrochloride, Procorum, G) was studied after single administration (2 mg i.v., 50 mg p.o.) of unlabelled and labelled G (14G, 2H). TLC, HPLC, GLC, MS and RIA were used for assessment of G and its metabolites in plasma, urine and faeces. G clearance is almost completely metabolic, with only minimal excretion of unchanged drug. Metabolites represent most of the plasma radioactivity after p.o. administration. They are formed by N-dealkylation and O-demethylation with subsequent N-formylation, or glucuronidation, respectively. Compound A, derived by loss of the 3,4-dimethoxyphenethyl moiety of G is the main metabolite in plasma and urine (about 20% of the dose). This metabolite is accompanied by its N-formyl derivative (C), by the N-demethylated compound (H) and the acid (F), formed by oxidative deamination of A. Only 3 unconjugated monphenoles from several O-demthylated products showed distinct plasma levels which were nevertheless lower than metabolite A. These metabolites had no relevance to the pharmacodynamic action. Conjugated monophenolic and diphenolic products represented the major part in plasma and were excreted predominantly via the bile: they represented almost the whole faecal metabolite fraction. Less than 1% of the dose was recovered unchanged in the urine. About 50% of the dose is excreted by urine and 40% by faeces.

Administration, Oral↗
PubMed1988

[Blood cell concentration of methotrexate in long-term therapy of inflammatory rheumatic diseases].

To verify the possibility of a concomitant therapy control in 31 patients (18 psoriatic arthritis [PA], 13 rheumatoid arthritis [RA]) the blood cell concentration of Methotrexate (MTX) was continuously measured over a period of 6 months. The determinations were carried out by using a RIA of the CIS Corp. At any time MTX was determined laboratory and clinical examinations were done and the P-III-P serum-level was measured by using a RIA of the Behringwerke. The cellular MTX showed to be statistically significantly elevated compared to baseline, whereas within ranges of total cumulative dosages only insignificant fluctuations could be noticed. Like in the treatment of Psoriasis a strict correlation between the weekly administered dose and the cellular MTX could be established, the total cumulative dose, however, had no influence on the cellular MTX-level. In the treatment of RA slightly higher weekly dosages were necessary, which caused significantly higher cellular MTX concentrations in RA patients. Some correlations between clinical as well as serological parameters of disease activity could be noticed, nevertheless they do not allow distinct interpretations. In both diseases a significant relationship between the cellular MTX-level and the P-III-P serum-level could be realized. A storage of MTX in blood cells, especially in erythrocytes, seems to be evident. To reach therapeutical benefit in RA slightly higher mean dosages may be necessary. A therapy monitoring by the means of continuous determinations of cellular MTX seems to be impossible. In contrast an approach to the early detection of liver fibrosis can be given by the correlation between cellular MTX and the P-III-P serum levels.

Adult↗
PubMed1987

Apolipoproteins C-II and C-III in serum quantified by zone immunoelectrophoresis.

Zone immunoelectrophoresis assays specific for apolipoprotein C-II and C-III have been developed. These simple, accurate, reproducible, and sensitive methods present valid alternatives to conventional immunoassays. In fasting normolipidemic men and women the concentrations of apolipoprotein C-II and C-III were 49 (SD 25) mg/L and 124 (SD 60) mg/L, respectively, with no sex-related differences for either apolipoprotein. The frequency distribution of apolipoprotein C-II was skewed to the right, whereas apolipoprotein C-III was bimodally distributed. Concentrations of each apolipoprotein correlated well with one another and with that of serum triglycerides, but there was virtually no correlation between the apolipoprotein C-II to C-III mass ratio and the concentration of triglycerides. Apolipoprotein C-III, but not apolipoprotein C-II, was statistically associated with total cholesterol.

Apolipoprotein C-II↗
PubMed1981

[Physiological importance of microvilli-bound leucine arylamidase in the final digestion of proteins. 1. Purification and isolation of intestinal leucine arylamidase and aminotripeptidase of rats].

The membrane-bound leucine arylamidase of the microvilli of the rat small intestine was solubilized by Triton X-100 and purified by gel and ion-exchange chromatography. As compared to the mucosa homogenate, the purification factor was 135. The leucine arylamidase and aminotripeptidase of the microvilli cannot be separated by chromatography. The cytosomal portion of the aminopeptidase is devoid of leucine arylamidase activity.

Aminopeptidases↗
PubMed1980

[Physiological importance of the microvilli-bound leucine arylamidase in the final digestion of proteins. III. Exopeptidatic activities of purified microvilli against peptides mixtures in the presence and after the removal of free amino acids].

The exopeptidatic degradation of peptide mixtures by the aminopeptidase of the microvilli is inhibited by the presence of free amino acids. Further degradation occurs after the removal of the free amino acids from the peptide mixture. The amino-acid composition of the remaining residual peptides is a second factor that impedes the complete cleavage of the peptides.

Amino Acids↗
PubMed1980

[Physiological importance of microvilli-bound leucinarylamidase in the final digestion of proteins. 4. Inhibition of microvilli-bound leucinarylamidase by free amino acids].

The microvilli-bound leucine arylamidase is inhibited by certain amino acids. An inhibitory action is exerted by the branched-chain amino acids L-leucine and L-isoleucine and by the aromatic amino acids L-tyrosine and L-phenylalanine with Ki values of 4--6 . 10(-3) M. L-methionine (Ki = 2.5 . 10(-3) M) and its higher homologue L-ethionine (Ki = 1.1 . 10(-3) M) are the most potent inhibitors. Derivatization of L-methionine on the sulphur or the nitrogen atom or the carboxyl group prevents the inhibitory effect just as the D-isomer.

Amino Acids↗
PubMed1978

'Limbic spindles': a re-appraisal.

Respiration-linked spindles are frequently recorded from nasopharyngeal electrodes and these have been reported to represent neuronally generated limbic activity. Evidence is presented from sphenoidal and nasopharyngeal recordings suggesting that these spindles are artifactual, due to unstable electrode contacts that record palatal vibration during partial airway obstruction.

Adult↗
PubMed1978

[Studies on the disposition of meproscillarin in rat and dog (author's transl)].

The disposition of 14-hydroxy-3beta-[(4-O-methyl-alpha-L-rhamnopyranosyl)oxy]-14beta-bufa-4,20,22-trienolide (meproscillarin, Clift) formed by methylation of proscillaridin was tested in rats and dogs. Meproscillarin is better absorbed than proscillaridin. The drug is primarily eliminated via the bile. After oral administration 6% of the dose were excreted with urine by the rat and 3% by the dog. The main metabolite in the bile was shown to be a glucuronide of meproscillarin.

Administration, Oral↗
PubMed1975

[Spectral-analytical studies of the action of etifoxin on the human EEG].

Spectral analysis of EEG in healthy volunteers shows that Etifoxin, the hydrochloride of 6-chloro-4-methyl-4-phenyl-2-ethylamino-4H-3,1-benzoxazine (Hoe 36,801), in an oral dosage of 100 mg has a differential effect in function of the individual alpha organization. This differential effect appearing in the course of the quantitative evaluation can be interpreted, from a morphological point of view, as an expression of various partial phases and patterns of a process leading to reduced vigilance.

Alpha Rhythm↗