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Biomedical subjects

H Geyer

Publications and source records attributed to H Geyer.

At least 109 records · Page 6Linked to original sources
PubMed1983

Methylation analysis of complex carbohydrates in small amounts: capillary gas chromatography-mass fragmentography of methylalditol acetates obtained from N-glycosidically linked glycoprotein oligosaccharides.

A version of the methylation analysis of complex carbohydrates by gas chromatography-mass spectrometry of the methylalditol acetates (H. Björndal, C. G. Hellerquist, B. Lindberg, and S. Svensson (1970) Angew. Chem. 82, 643-674) is described. With this version 100- to 500-pmol samples of N-glycosidically linked glycoprotein oligosaccharides may be analyzed. The method is based on the use of capillary columns which allow the separation of all partially methylated alditol acetates potentially obtained from this group of oligosaccharides and on their selective and sensitive detection by mass fragmentography after chemical ionization with ammonia.

Chromatography, Gas↗
PubMed1983

[Estrogen and progesterone receptors in malignant ovarian neoplasms].

Estrogen receptors (ER) and progesterone receptors (PR) were evaluated in 173 primary ovarian cancers and in 6 ovarian metastases. In epithelial ovarian carcinomas 63% had ER and 46% PR. Almost all granulosa cell tumours were receptor-positive, while sarcomas, dysgerminomas, and teratomas lacked ER and PR. Both receptors were found less often in tumours of the histological grade I than in those of grade II and III. During the development of metastases and during chemotherapy there was a loss of PR in 27% and 53% of the cases, respectively, while the amount of ER remained more or less constant. In addition to ovarian cancers ER and PR were present in carcinomas of the fallopian tube as well. ER-negative and especially PR-negative tumours seemed to respond better to chemotherapy than receptor-positive carcinomas. The possible significance of ER and PR with regard to the success of an endocrine treatment is discussed.

Carcinoma↗
PubMed1982

Separation procedure and sugar composition of oligosaccharides in the surface glycoprotein of Friend murine leukemia virus.

The sugar composition of the surface glycoprotein from Friend murine leukemia virus was determined by gas-liquid chromatography of the alditol acetates and by the thiobarbituric acid method, respectively. N-Acetylglucosamine, mannose, galactose, sialic acid and fucose were found in a molar ratio around 15.2:11.6:7.4:3.3:1.0. Ten oligosaccharide fractions were obtained from glycoprotein preparations by a suitable sequence of degradation (with pronase, endo-beta-N-acetylglucosaminidase H, neuraminidase, and by hydrazinolysis) and separation procedures (concanavalin A-affinity chromatography and gel filtration). The qualitative sugar composition of these fractions was analyzed by in vivo labelling with D-[6-(3)H]glucosamine, D-[2-(3)H]mannose, D-[6-(3)H]galactose, or L-[6-(3)H]fucose, and their molecular weights were estimated from the gel elution volumina. Four fractions of N-glycosidically linked oligosaccharides of the oligomannosidic ('high mannose') type oligomannosidic7-oligomannosidic10, about seven to ten sugar residues), two of the mixed (M11 and M12), and four of the N-acetyllactosaminic ('complex') type (N-acetyllactosaminic9, probably nine sugar residues; N-acetyllactosaminica-N-acetyllactosaminic c, size unknown) were thus identified.

Chromatography, Affinity↗
PubMed1982

Immunochemical properties of oligosaccharide-protein conjugates with Klebsiella-K2-specificity. II. Protective capacity of the conjugates and anti-conjugate antibodies against infection with Klebsiella pneumoniae 01:K2 in mice.

Oligosaccharide subunits from Klebsiella pneumoniae B5055 capsular polysaccharide, covalently linked to protein carriers, the native polysaccharide, and killed whole bacteria, were compared with respect to their immunogenicity in mice and their capacity to protect mice against bacterial infection. The protection was studied (a) by active immunization and (b) by passive administration of antisera raised in rabbits using the different immunogens. The results were as follows: in the active protection experiments the octa- and dodecasaccharide conjugates were as effective as the polysaccharide in increasing the LD50 by a factor of 10(5) as compared to nonimmunized animals. Thus, these antigens were only slightly less effective than killed bacteria. In contrast the tetrasaccharide conjugate was at least 1000-fold less effective than all other antigens used. In the passive protection experiments these results were paralleled in that the antiserum against the tetrasaccharide conjugate also showed the lowest degree of protection, though, for methodical reasons, the differences in the LD50s were less pronounced. The drastically lower efficiency of the tetrasaccharide in comparision to its higher oligomers is in agreement with serological findings previously published (see first communication), which showed that two repeating units are the minimum requirement for a substantial representation of polysaccharide serological specificity.

Animals↗
PubMed1982

Comparison of the actions of trimethadione and chlordiazepoxide in animal models of anxiety and benzodiazepine receptor binding.

Trimethadione was compared with chlordiazepoxide for anti-anxiety activity in two behavioral tests known to predict the anxiolytic action of drugs. In the drug-discrimination test, male hooded rats were trained to discriminate the anxiogenic action of pentylenetetrazol from saline by responding for food reinforcement on one of two levers after treatment with pentylenetetrazol (1450 mumol/kg) and on the other lever after injection of saline. Pretreatment with either chlordiazepoxide (2.8-33 mumol kg) or trimethadione (559-2236 mumol/kg) prior to the injection of pentylenetetrazol, produced a dose-dependent antagonism of the anxiogenic stimulus. In the other test, male Wistar rats were trained to respond for milk reinforcement in a conflict procedure in which some of the reinforced responses resulted in the delivery of footshock. Treatment of these rats with chlordiazepoxide (17-67 mumol/kg) or trimethadione (1118-2236 mumol/kg) antagonized the footshock-induced suppression of responding. In a receptor binding study, trimethadione failed to inhibit flunitrazepam binding. These data suggest that trimethadione is an effective anxiolytic agent whose action does not directly involve benzodiazepine receptors.

Animals↗
PubMed1982

[Estrogen and progesterone receptors in corpus uteri carcinoma and their clinical significance].

In 49 carcinomas of the endometrium of varying clinical stages the estrogen and progesterone receptors were studied by charcoal absorption methods. The cases were studied between 1979 and 1981. 64% of the investigated cases were receptor positive, 35% were receptor negative. Estrogen receptors were detected in 61% and progesterone receptors in 49% of the cases. Both estrogen and progesterone receptors were detected in 45% of the cases. The receptor status was correlated with the clinical stage, the microscopic differentiation and the age of the patient. In 30 cases with a follow-up of more than 3 months it was attempted to determine the prognostic value of the steroid receptor status in endometrial carcinoma. The treatment possibilities with progestational agents and antiestrogens and with tamoxifen were discussed in view of the receptor status.

Age Factors↗
PubMed1982

Oestrogen and progesterone receptors in the involuting rat uterus.

The concentrations of cytoplasmic oestrogen and progesterone receptors were measured in rat myometrium during the post partum involution of the uterus. The concentration of the oestrogen receptor declined within 24 h post partum to about 20% of the value at delivery. A slight rise in the concentration occurred during the subsequent 24 h. The concentration of the progesterone receptor remained nearly constant the first day after delivery. Thereafter it decreased just as the concentration of the oestrogen receptor had fallen one day before. The results suggest that the post partum levels of oestrogen and progesterone receptors are regulated by the same mechanisms as those known for the non-pregnant state.

Animals↗