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Biomedical subjects

G Becker

Publications and source records attributed to G Becker.

At least 289 records · Page 16Linked to original sources
PubMed1979

Capacity of the mucosal transfer system and absorption of iron after oral administration in rats.

1. The dose dependence of the iron absorption shows a saturation characteristic if iron (0.25--5 mumoles Fe/kg body weight) is administered in tied-off intestinal segments of normal and iron-deficient rats. 2. If the iron doses (2.1--570 mumoles Fe/kg body weight) are administered by stomach tube only in normal rats a similar dose dependence curve has been obtained as after administration in tied-off intestinal segments. In iron-deficient rats the shape of the dose dependence curve is changed and shows no clear-cut saturation characteristic. 3. The differences of these dose dependence curves are discussed with respect to the differences of the methodological conditions. A saturation type kinetic for absorption cannot be expected under all experimental conditions despite of the existence of a transfer system with limited capacity for the transport of iron.

Animals↗
PubMed1979

Intestinal absorption of cobalt and iron: mode of interaction and subcellular distribution.

1. The absorption kinetic of 59Fe-(FeCl3) and 60CO-(CoCl2) 10 min after administration of increasing doses (0.5--1,000 nmoles metal) into tied-off duodenal segments of normal and iron-deficient rats shows saturation characteristic for both metals; in iron-deficient rats the absorption of both metals was enhanced. 2. The addition of increasing amounts of cobalt to the 59Fe-containing test solutions caused a decrease of the absorption of iron. 3. The study of the time dependence of this interaction in iron-deficient rats revealed, that cobalt inhibits the release of iron from mucosal cells into the blood, whereas the uptake of iron from the lumen into the mucosal cells did not differ from the controls without administration of cobalt. 4. The subcellular distribution of 59Fe and 60 Co in mucosal cell homogenates of iron-deficient rats after ultracentrifugation on a polyvinylpyrrolidone-CsCl solution shows a similar pattern for both metals; in the presence of cobalt the subcellular distribution of 59Fe is not changed. 5. From these results the conclusion is drawn that cobalt inhibits iron absorption not by an interference with iron binding sites on or in the luminal membranes of the mucosal cells but by an interaction with the releasing process at the contraluminal side.

Animals↗
PubMed1978

Reflux nephropathy and chronic atrophic pyelonephritis: a review.

Chronic atrophic pyelonephritis is associated with vesicoureteric reflux in infancy. Reflux disappears during childhood in 50% of cases. It is more commonly detected in infants (49%) and children (26%) with infection than in adults (4.4%). Severe reflux may persist in adults and is usually (94%) associated with scarring. Patients with end-stage renal failure due to pyelonephritis are much younger than patients with end-stage renal failure due to other causes. The incidence of reflux according to sex is equal in infancy, but after infancy both pyelonephritic scarring and reflux are far more common in females. Infection is the likely cause of progressive scarring in females. Hypertension is associated with chronic atrophic pyelonephritis. Proteinuria is the worst prognostic feature in patients with reflux nephropathy and pyelonephritic scarring. Intrarenal reflux determines the site of scarring. The role of surgical correction of vesicoureteric reflux remains uncertain, but meticulous control of infection appears to prevent progressive scarring.

Adolescent↗
PubMed1978

[Diffuse segmental lipomatosis of the ileum (author's transl)].

Case of unusual diffuse segmental lipomatosis of a part of the small bowel is reported. Other cases from the literature are compared to various pathological deposits of fat in the intestine. Aetiology, clinical signs, diagnosis and differential diagnosis, as well as surgical treatment, are discussed.

Adult↗
PubMed1977

An improved percutaneous jetting system for use during microlaryngeal operations.

Studies carried out in the laboratory have shown that an S-shaped cannula for trans-laryngeal jet ventilation provides a distinct advantage over conventional straight ones. Tidal volumes are larger and the cannula is more stable in position. The tendency of perforate the posterior wall of the trachea during introduction is also minimal. Blood gas data obtained from patients being operated upon with this technique of anaesthesia show that it provides very adequate ventilation and can be effectively used with balanced anaesthesia if a nitrous oxide-oxygen blender is incorporated into the jetting system. It can be put in position before induction of anaesthesia to enable preoxygenation and assist ventilation and can be left in place at the end of the operation until the patient is breathing adequately. If necessary, a tracheostomy can be done with the cannula in situ. It is not proposed that this should be the standard mode of anaesthesia or ventilation for patients undergoing operations on the larynx, but in stituations where other methods are not adequate and when significant upper airway obstruction is present, this is an excellent alternative.

Aged↗
PubMed1977

Crucial role of the postnatal maternal environment in the expression of prenatal stress effects in the male rats.

Methodological and conceptual problems common in prenatal stress experiments were analyzed, and an experiment incorporating solutions to those problems were designed and executed. Rats were prenatally stressed or served as controls and then were cross-fostered within or between treatment groups. In adulthood, one male from each litter was tested over 20 trials in an open-field box and then tested over 20 successive discrimination reversals in a T-maze. A T-factor analysis was performed on each of the two sets of observations, and factors scores were subjected to elevational analyses. Major hypotheses generated from the results are the following: (a) Male rats subjected to prenatal stress acquire emotional reactivity levels in adulthood that are either elevated or reduced depending on the postnatal maternal environment. (b) Male rats subjected to prenatal stress acquire reversal learning sets in adulthood with a rapidity that parallels and indeed is produced by the pattern of emotional reactivity reflected in the above a and as mediated by cognitive processes. (c) T-factor analysis of trials is required in order to avoid construct validity problems as well as internal validity problems, both brought about by the confounding of trial variables, and in addition, it may generate valuable hypotheses giving further meaning to the dependent variables under observation.

Animals↗
PubMed1976

[Results of radiotherapy of bronchial carcinoma (author's transl)].

In a joint retrospective study by 17 radiotherapy clinics in German-speaking countries the results of treatment of bronchial carcinoma after radiotherapy were analysed in 7503 cases. The age peak was between the 60th and 70th year. Squamous-cell carcinoma was the most frequent histological type, followed by anaplastic carcinoma, with adenocarcinoma being rare. There was a high proportion of histologically not clearly identified cases (27% in central and 35% in peripheral carcinomas). Survival rate at one year was 31% for central (3662 patients) and peripheral (961 patients) tumours, but only 2% at five years. Prognostically there was no difference between histological types and kind of radiotherapy or technique, but total dose affected survival rate. At a total dose of less than 5000 rd the survival rate at five years was minimal. The prognosis of combined surgical and radiotherapeutic measures was slightly better than with a radiotherapy alone, but results were unpredictable for the individual case. It is concluded that radiotherapy aiming at cure should be used in imoperable bronchial carcinoma if the tumour state and general condition of the patient appear to make a cure possible. But if this is not the case, radiotherapy should be used only palliatively, i.e. only to ameliorate symptoms.

Adenocarcinoma↗
PubMed1976

The separation of partially modified lactate dehydrogenase by affinity chromatography. The specific activity of protomers?

Pig heart lactate dehydrogenase (L-lactate: NAD+ oxidoreductase, EC 1.1.1.27) was partially inactivated by reaction with phenylmaleimide. The resulting protein mixture was separated by affinity chromatography on a Sepharose-linked oxamate column yielding three distinct enzyme fractions with one, two and three out of four subunits being modified. The specific activities of these samples were lower than expected from the degree of modification, while the maximum binding capacity of NADH-oxamate related well to the number of catalytic centers modified. A possible cooperative effect in the native enzyme is discussed.

Animals↗
PubMed1976

Diagnostic value of gallium-67 in malignant lymphoma.

The results of lymphangiography and other radiologic procedures are compared with those obtained by 67Ga scintigraphy in staging of 27 patients with Hodgkin's disease and 31 patients with non-Hodgkin's lymphoma. A high degree of correlation was found between lymphangiography and 67Ga scintigraphy. Exact localization, however, was only possible by lymphangiography. In some cases, the extent of disease found on scanning appeared to be smaller compared to radiography. Within the chest 67Ga scintigraphy and conventional radiography give almost similar results. Differentiation between neoplastic and inflammatory lymph node involvement is impossible.

Drug Evaluation↗
PubMed1975

Differences and similarities between guanosine 3',5'-cyclic monophosphate phosphodiesterase and adenosine 3',5'-cyclic monophosphate phosphodiesterase activities in neuroblastoma cells in culture.

There are phosphodiesterase activities in both particulate and supernatant fractions which hydrolyze guanosine 3',5'-cyclic monophosphate (cGMP) and adenosine 3',5'-cyclic monophosphate (cAMP) with an apparent Km of 2-8 muM and with an apparent Km of 44-222 muM. 4-(3-Butoxy-4-methoxybenzyl-2-imidazolidinone (RO20-1724) did not inhibit cGMP phosphodiesterase activity in homogenates of mouse neuroblastoma cells, but markedly inhibited cAMP phosphodiesterase activity. Papaverine and theophylline inhibited both cGMP and cAMP phosphodiesterase activities to about the same extent. The former was more potent than the latter. The specific activity of cGMP phosphodiesterase as a function of protein concentrations first increased and then decreased. The specific activity of cAMP phosphodiesterase decreased under a similar experimental condition.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1975

[Case report: adenocarcinoma of the kidney developing metastzsizing to both lungs, with numerous microliths radiologically imitating Microlithiasis alveolaris pulmonum (author's transl)].

A 28 years old man developed a radiological pattern like Microlithiasis alveolaris pulmonum during the following five years after exstirpation of his right kidney due to an adenocarcinoma. Tests showed, in contrast to the x-ray pulmonary function, only a slight restriction of total lung capacity over a long time up to few months before he died. Autopsy showed a spread of miliary and submiliary metastases in the lower parts of both lungs. In all metastases psammomabodylike microliths were found microscopically, especially numerous and enlarged with both lungs. A second check of the slides of the primary tumour showed rare microliths too, not mentioned at that time. A microlith producing tumour of the kidney was first published with full details by Lubarsch in 1925. The radiological aspect of the lungs of the reported case reveals serious differential diagnostical problems to Microlithiasis alveolaris pulmonum.

Adenocarcinoma↗
PubMed1975

Effect of neurotransmitters, Guanosine triphosphate, and divalent ions on the regulation of adenylate cyclase activity in malignant and adenosine cyclic 3':5'-monophosphate-induced "differentiated" neuroblastoma cells.

The effect of acetylcholine, 3,4-dihydroxyphenylethylamine, prostaglandin (PGE1), guanosine triphosphate (GTP), and divalent ions on adenylate cyclase activity in homogenates of ""differentiated" and malignant mouse neuroblastoma cells was studied. The sensitivity of adenylate cyclase to acetylcholine and 3,4-dihydroxyphenylethylamine markedly increased in adenosine cyclic 3:5-monophosphate-induced differentiated neuroblastoma cells. Although 3,4-dihydroxyphenylethylamine stimulated adenylate cyclase activity in malignant neuroblastoma cells, it failed to do so in X-irradiation induced differentiated cells. PGE1 and GTP stimulated adenylate cyclase activity in malignant and adenosine cyclic 3:5-monophosphate induced differentiated neuroblastoma cells to about the same level. GTP protentiated the PGE1 effect in differentiated concentrations of magnesium and manganese inhibited adenylate cyclase activity; this effect was more pronounced in differentiated cells than in malignant cells. Calcium stimulated adenylate cyclase activity in malignant and differentiated cells to about the same level. There was no significant difference in the values of Km and Vmax of neuroblastoma cells. This study shows that the sensitivity of adenylate cyclase to neurotransmitters and divalent ions (magnesium and manganese) and the sensitivity of PGE1 stimulated enzyme activity to GTP increase in adenosine cyclic 3:5-monophosphate-induced differentiated neuroblastoma cells. Therefore, we suggest that the reverse may be true during malignant transformation of nerve cells.

Acetylcholine↗