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Biomedical subjects

R Baumann

Publications and source records attributed to R Baumann.

At least 181 records · Page 10Linked to original sources
PubMed1983

Assignment of the 1H nuclear magnetic resonance spectrum of the trypsin inhibitor homologue K from Dendroaspis polylepis polylepis. Two-dimensional nuclear magnetic resonance at 360 and 500 MHz.

The assignment of the 1H nuclear magnetic resonance (n.m.r.) spectrum of the trypsin inhibitor homologue K from the venom of Dendroaspis polylepis polylepis is described and documented. The assignments are based entirely on the amino acid sequence and on 2-dimensional n.m.r. experiments at 360 and 500 M Hz. Individual assignments were obtained for the backbone and C beta protons of all 57 residues of the inhibitor homologue K, with the exceptions of the N-terminal amino group, the amide protons of Arg16, Gly37 and Gly40 and the C beta protons of Arg16 and Pro19. The assignments for the non-labile protons of the amino acid side-chains are complete, with the exception of Gln29, Glu49 and all the proline, lysine and arginine residues. For Asn and Trp the labile side-chain protons have also been assigned. The chemical shifts for the assigned resonances are listed for an aqueous solution at 50 degrees C and pH 3.4.

Amino Acid Sequence↗
PubMed1983

Two patients with pancreatic apudomas secreting neurotensin and VIP.

Two patients have been studied with a two and a half and nine year history of metastatic pancreatic apudoma. In both patients the main feature was chronic watery diarrhoea with remissions after partial tumour resection and streptozotocin therapy. Plasma levels of circulating VIP and neurotensin were persistently raised in both patients. Chromatographic analysis of the plasma showed that a significant proportion of the raised immunoreactivity of both peptides eluted in an identical position to pure VIP and neurotensin. The extremely high concentrations of neurotensin did not appear to result in any feature which would allow distinction from the classical VIPoma syndrome.

Adult↗
PubMed1983

Effects of hypoxia on oxygen affinity, hemoglobin pattern, and blood volume of early chicken embryos.

We have investigated the influence of hypoxia (13.5% O2) on the oxygen affinity, hemoglobin pattern, and blood volume of chicken embryos. Data were collected between 4 and 9 days of incubation. It was found that the transition from embryonic to adult hemoglobin starts earlier in hypoxic embryos, due to a premature appearance of definitive red cells in the circulation. Blood oxygen capacity and total blood volume (related to embryonic weight) were not different from the controls. However, hypoxic embryos weighing more than 0.1-0.2 g have a significantly increased oxygen affinity (and decreased red cell adenosine 5'-triphosphate concentration). The higher O2 affinity partly compensates for the adverse effects of the lowered environmental PO2. In hypoxic embryos younger than 6 days, the Bohr effect is drastically increased, which allows a better oxygen extraction. Thus, the chicken embryo seems to be able to develop adaptive changes of blood O2 transport during hypoxia. The results support the view that the particular ontogenetic pattern of O2 affinity changes seen in avian or mammalian embryos arose from the need to adapt to the steadily changing conditions for O2 uptake.

Animals↗
PubMed1983

[Primary structures of the alpha and beta chains from the major hemoglobin component of the ostrich (Struthio camelus) and American rhea (Rhea americana) (Struthioformes). Aspects of respiratory physiology and taxonomy].

The primary structures of the alpha A- und beta-chains from the major hemoglobin component of the Ostrich (Struthio camelus) and American Rhea (Rhea americana) are given. The minor component with the alpha D-chains was detected in Ostrich in several concentrations, in American Rhea as in chicken and pheasant (about 40%). By homologous comparison, Greylag Goose (Anser anser) hemoglobin and Ostrich alpha A-chains differ by 15 amino acids or 16 nucleotide (1 two-point mutation) exchanges, beta-chains by 4 exchanges. Four substitutions modify alpha 1 beta 1-contacts and one phosphate contact. American Rhea and Greylag Goose hemoglobin alpha A-chains differ by 20 amino acids or 23 nucleotides (3 two-point mutations), beta-chains by 4 exchanges. Two substitutions modify alpha 1 beta 1-contacts, one phosphate contact and one heme contact. Oxygen affinity of three hemoglobin components of Ostrich are measured and the results are discussed. Systematic and evolution of Ostrich and American Rhea are discussed.

Amino Acid Sequence↗
PubMed1982

[Clinical aspects of typical changes in carbohydrate and lipid metabolism in essential hypertension].

Taking into consideration regulative aspects and perceptible interrelations with pressor and depressor systems some typical alterations of the carbohydrate and lipid metabolism in patients with essential arterial hypertension are summarized. An increased hormone-induced lipolysis is associated with impaired carbohydrate tolerance. Glucose-stimulated insulin response is enhanced in hypertensives, even if glucose tolerance is normal. In subjects with essential hypertension the percentage of linoleic acid in serum triglycerides is augmented, but decreased in subcutaneous adipose tissue. The fat cell volume is not different from that in normotensive probands. The mostly mild disturbances of carbohydrate and lipid metabolism are already evident in early stages of essential hypertension and indicate syndrome-like interrelations which should be analysed systematically and which are of fundamental significance for the causal proof of primarily preventive strategies for the reduction of the cardiovascular risk.

Adipose Tissue↗
PubMed1982

Functional properties of embryonic chicken hemoglobins.

We have investigated the O2-binding properties of the four embryonic hemoglobins (Hb P, Hb P', Hb M, and Hb E) under various conditions and compared the results with measurements on early embryonic chicken blood between 3 and 6 days of incubation. The O2-binding curve of embryonic blood is polyphasic. Hill's coefficient changes continuously from less than or equal to 1 at low O2 saturation to a value of approximately equal to 8 in the upper saturation range. The high cooperativity is coupled with a very low O2 affinity in the middle range of the O2-binding curve. Between 3 and 6 days of development the O2 affinity and cooperativity as well as the Bohr effect of embryonic blood change drastically, without corresponding alterations of the hemoglobin pattern or ATP concentration. The functional properties of the embryonic blood cannot be simulated with the isolated embryonic hemoglobins at physiological concentrations of ATP, hemoglobin, and protons. On the other hand, freshly prepared hemolysate shows the same functional pattern as the embryonic blood. The results suggest that embryonic red blood cells may contain other low-molecular-weight substances that reduce the O2 affinity and increase the cooperativity of the major embryonic hemoglobins, Hb P and Hb P', presumably by promoting tetramer-tetramer aggregation.

Adenosine Triphosphate↗
PubMed1981

[Stress-ulcer. Prevention and therapy by cimetidine (author's transl)].

Efficiency of cimetidine in therapy and prevention of stress ulcer has been tested in a double blind study with endoscopic examination at the time of inclusion and a week later. This study concerns forty patients with severe cerebral disorders and prolonged coma. In preventive group (20 subjects) we noticed 55 p. cent of success under placebo and 37 p. cent with cimetidine. In therapy group (20 subjects) cimetidine was not different from placebo (37,5 of success v. s. 41,25 p. cent). Two patients presented hematemesis. The relative failure of cimetidine in these patients is discussed and some explanations are envisaged.

Adolescent↗
PubMed1980

Ovulation inhibition by daily i.m. administration of a highly active LH-RH analog (d-ser(TBU)6-LH-RH-(1-9)-nonapeptide-ethylamide).

A highly active LH-RH-analog (D-Ser(TBU)6-LH-RH-(1-9)-nonapeptide-ethylamide = HOE 766) was administered to normally cyclic and ovulatory women in a double-blind study. Each woman received from day 1 through day 14 of the cycle according to a randomization plan either 10 microgram HOE 766 i.m. or a placebo. Ovulation was inhibited for at least two weeks in all subjects receiving HOE 766. The initially very marked release of LH measured 4 hourse after the injection decreased within 3 days by approximately 50%, and remained at this level for the remainder of the experiment while the initially high FSH response was abolished during further treatment. In 3 out of 5 women receiving the analog, serum estradiol was severely suppressed, in the remaining 2 slightly. Within 5 days after the discontinuation of treatment, the pituitary had regained the capacity to respond normally to LH-RH. It is postulated that follicular maturation is disturbed by the unphysiologic pattern of gonadotropin secretion during administration of HOE 766.

Adult↗
PubMed1980

Competition of various LH--RH analogs and fragments with 135I-LH--RH for specific binding sites on isolated pituitary plasma membranes.

The displacement by various LH--RH analogs and fragments of 125I-LH--RH specifically bound to plasma membranes isolated from rat anterior pituitaries was investigated. The addition of increasing amounts of unlabelled LH--RH resulted in an increasing displacement of bound 125I-LH--RH. When some fragments of LH--RH or of an analog with little biological activities were incubated, a much weaker affinity for LH--RH binding sites could be observed. No correlation between biological effectiveness and binding affinity was, however, found when several highly active LH--RH analogs were tested. The potent analogs competed much less efficiently for specific binding sites on isolated plasma membranes than LH--RH. Binding experiments with iodine-labelled (D-Ser(But)6-LH--RH(1--9)-nonapeptide-ethylamide indicated that the small binding affinity of the superactive analog may be due to a lower association rate while the dissociation rate is comparable to that of LH--RH. Contrary to LH--RH, no binding equilibrium was reached during 2 h of incubation of the analog with plasma membranes. The physiological role of LH--RH binding sites on isolated pituitary plasma membranes remains to be elucidated.

Animals↗
PubMed1980

Ligand-linked changes of ultrasound absorption of hemoglobin.

The acoustic absorption of hemoglobin solutions at 1.88 MHz has been studied in dependence of ligand binding and pH. In the physiological pH range the excess absorption of oxyhemoglobin is increased compared to deoxyhemoglobin. Evidence is presented that in human hemoglobin the additional absorption of oxyhemoglobin is caused by a proton transfer relaxation process involving the alpha chain N-terminal alpha-amino groups. This process cannot be observed in deoxyhemoglobin because of fixation of the N-terminal alpha-amino groups in a salt bridge. Further investigations of carbonmonoxy, nitrosyl, aquomethemoglobin and fluoromethemoglobin in the absence and presence of inositol hexakissulfate show that acoustic absorption measurements offer an additional tool to characterize in greater detail the different conformational states of hemoglobin.

Animals↗
PubMed1980

High postheparin lipolytic activity as a possible cause of hypotriglyceridemia in spontaneously hypertensive rats.

In male spontaneously hypertensive rats (SHR) and normotensive Wistar rats at 4, 8 and 20 weeks of age the postheparin lipolytic activity (PHLA) has been estimated. PHLA was significantly higher in all SHR than in age- and weight-matched controls, although it decreased with advancing age in both groups. The data are discussed with regard to hyperinsulinemia and hypotriglyceridemia in SHR ascertained by a previous study. It is assumed that in young SHR catecholamine-induced lipolysis provokes impaired glucose tolerance and higher insulin response after glucose load. Insulin enhancement can stimulate PHLA via increased synthesis of lipoprotein lipase. The resulting augmented uptake of triglycerides by adipose tissue is suggested to be a beneficial (adaptive?) mechanism to compensate a primary increase of lipolysis. The well-known lower adipose cell size and body weight in SHR in comparison to age-related normotensive control rats might indicate that this mechanism is insufficient to balance the triglyceride supply in these animals.

Animals↗