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Biomedical subjects

R Schmid

Publications and source records attributed to R Schmid.

At least 343 records · Page 19Linked to original sources
PubMed1977

[Contraceptive efficiency of triphasic inhibitors (author's transl)].

The effects of two newly developed triphasic preparations with a sequence of 6/5/10 and a reduced content of the total dose of oestrogen per cycle on the parameters of cycle function were studied in 10 young women with normal phasic cycles using a randomized trial design. Cervical function, spinnbarkeit and crystallisation of cervical secretion and the karyopyknotic index were monitored and LH,E2 and progesterone levels in serum radioimmunologically determined in a pretreatment control cycle, the immediately following 1st treatment cycle, the 3rd treatment cycle and a subsequent treatment-free cycle. Both preparations brought about suppression of ovulation already in the 1st treatment cycle with the periphery (cervical barrier) greatly reduced but still reactive. The results of the study show that by adapting the ratio of active substances to the phases of the normal cycle, not only good cycle control and tolerance are achieved but also inhibition of ovulation.

Adult↗
PubMed1977

Arginine modifiers as energy transfer inhibitors in photophosphorylation.

Photophosphorylation by spinach chloroplasts is inhibited after they have been incubated in the dark with either phenylglyoxal or butanedione. Inhibition by phenylglyoxal is strongest when N-ethylmorpholine is the buffer used during the incubation; that by butanedione requires the presence of borate as buffer. The inhibitions are not reversed by simply washing out the inhibitor, suggesting that a covalent modification of one or more arginine residues is responsible. This is supported by the reversibility of the butanedione inhibition if both the inhibitor and borate buffer are removed. ATPase of the chloroplasts, and of extracted protein, is inhibited, whether activated by trypsin or by heating. This indicates that arginine residues of the coupling factor are the probable major site(s) for attack by these modifiers, leading to the observed inhibitions.

Aldehydes↗
PubMed1977

Specific and sensitive method for the determination of gamma-aminobutyric acid using gas chromatography with electron-capture or mass fragmentographic detection.

A gas chromatographic method for the determination of gamma-aminobutyric acid (GABA) in brain tissue is described. After microwave fixation, the brains were dissected and homogenized in 0.1 N formic acid; delta-amino-n-valeric acid (AVA), a homologue of GABA, was then added as an internal standard. After centrifugation, aliquots of the supernatant were treated with cation-exchange paper to adsorb the amino acids. The eluates of this paper were dried and the residues subjected to reaction with trifluoroacetic anhydride and hexafluoroisopropanol. After removal of the derivatization reagents by evaporation, the residues were dissolved in ethyl acetate and an aliquot was analysed by gas chromatography with electron-capture or mass fragmentographic detection. Quantitation can be carried out by either peak-height or peak-area measurements. The specificity of this method has been demonstrated with brain tissue by simultaneous mass fragmentographic analysis. The sensitivity is comparable to that of mass fragmentographic methods and is in the femtomole range. The method is simple and readily automated.

Aminobutyrates↗
PubMed1977

[Central and peripheral actions of an oral contraceptive with reduced oestrogen content (author's transl)].

The action spectrum of an oral contraceptive which contained a reduced amount of the oestrogen component (0.04 mg ethinyl-oestradiol and 2.0 mg lynoestrenol) was investigated in 4 volunteer subjects. Serum levels of LH, 17 beta-oestradiol and progesterone were determined by radioimmunoassay and, in addition, the karyopyknotic index and cervical function were studied daily from the 8th day of the cycle. These parameters were determined in a control cycle, in the cycle during administration of the oral contraceptive and in the subsequent treatment-free cycle. Furthermore, the bleeding patterns were studied in 284 treatment cycles of 26 patients. Results of these studies indicate complete contraceptive protection by inhibition of ovulation and by an efficient cervical barrier action already during the first treatment cycle. Withdrawal bleeding was observed 3 to 4 days after ingestion of the last tablet. Spotting was recorded in 11 subjects during the first treatment cycle but was rarely observed during further treatment. Blood loss and bleeding control is comparable to that of other combined oral contraceptives with reduced oestrogen content.

Adolescent↗
PubMed1976

The coupling factor of photophosphorylation and the electric properties of the thylakoid membrane.

The rate of ATP synthesis of illuminated chloroplasts is correlated with the electric conductance of their inner membranes. In agreement with previous studies it is shown that ATP synthesis is paralleled by an increased conductance of the thylakoid membrane. This conductance together with the ability to form ATP is abolished if chloroplasts are treated with an antibody against the coupling factor CF1. It is not influenced by the fragmented monovalent antibody. This parallels the lack of influence of the fragmented antibody on ATP synthesis in contrast to its influence on hydrolysis and exchange reactions. We conclude that there are different sites for the interaction of the coupling factor with adenine nucleotides. Extraction of the coupling factor is shown to increase the membrane conductance by more than two orders of magnitude. Reincorporation of the crude coupling factor partially restores the net conductance of the membrane (increase in resistance by a factor of 2.5), while a higher degree of restoration was observed for ATP synthesis and the proton conductivity of the membrane. We conclude that the extraction procedure opens different conductive channels in the membrane; a proton specific one, possibly associated with the binding protein for the coupling factor, plus other channels for "non-protons" which in contrast to the proton channel cannot be plugged by reincorporation of the coupling factor.

Adenosine Triphosphate↗
PubMed1976

Haemocyanins in spiders, III. Chemical and physical properties of the proteins in Dugesiella and Cupiennius blood.

The haemolymph of the tarantulas, Dugesiella (Eurypelma) californica and Dugesiella (Eurypelma) helluo contains high molecular weight haemocyanin (80-82% of total blood proteins) and a second protein not related to haemocyanin (18-20%). In the Lycosid spider, Cupiennius salei, haemocyanin (75% of total blood protein) occurs in two states of association. The haemocyanins were isolated by ultracentrifugation, gel filtration, isoelectric focusing, or preparative gel electrophoresis. Their sedimentation constants are 36.7 S (both tarantulas), 23.4 S and 15.9 S (Cupiennius). After alkaline dissociation, polypeptides sedimenting at 5.8 S (D. californica) and 4.7 S (Cupiennius) were obtained. The molecular weight of the intact functional subunit is (by sedimentation equilibrium) 70 300 (D. californica) and 69 900 (Cupiennius). Copper analysis results in closely similar values. By sodium dodecylsulphate gel electrophoresis, molecular weights of 71 000 (D. californica), 72 000 (Cupiennius) and 74 000 (D. helluo) were obtained. Denaturation with various agents did not lead to smaller polypeptides. The amino acid composition of the haemocyanins was determined (Table 1). The amino end group is blocked. The haemocyanins contain 1.2-1.5% of neutral carbohydrates and 0.3-0.5% of glucosamine (possibly acetylated). The neutral carbohydrates were identified with glucose, mannose, fucose, and arabinose, glucose being the dominant species. Neuraminic acid was not detected. The haemocyanins of the three species cannot be distinguished by their carbohydrate moieties, while there is a significant difference in amino acid composition between tarantula and Cupiennius haemocyanins. The second, non-respiratory protein isolated from spider blood sediments with 16.1 S (Dugesiella) or 15.9 S (Cupiennius). Its isoelectric point is at pH 5.5 It is stable in weakly alkaline solutions but can be denatured to yield polypeptide chains with molecular weights of 95 000 and 110 000. The amino acid composition is reported. As in the haemocyanins, the N-terminus is blocked. The carbohydrate content is 0.9%, glucose being the only sugar identified.

Amino Acids↗