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Biomedical subjects

H Weber

Publications and source records attributed to H Weber.

At least 307 records · Page 17Linked to original sources
PubMed1988

Protein malnutrition in the domestic fowl induces alterations in adrenocortical function.

Adrenocortical function was investigated in immature, dietary protein-restricted domestic fowl (Gallus gallus domesticus). White Leghorn cockerels (2 weeks old) were fed isocaloric semipurified diets containing either 8% [low (L)] or 20% [normal (N)] soy protein for 4 weeks ad libitum. Cockerels were quickly killed by decapitation and exsanguination. Trunk plasma corticosterone (B) and ACTH levels were measured by RIA. Maximal B-binding capacity (CBC) of plasma was also measured. In addition, in randomly selected cockerels, a rough index of the B clearance rate was determined. Finally, to determine the influence of protein malnutrition on adrenocortical cell function per se, we measured the acute (2-h) B responses of highly enriched adrenocortical cell populations to various ACTH analogs, 8-bromo-cAMP (8-Br-cAMP), and cellular B production maximally supported with 25-hydroxycholesterol. Plasma B and ACTH concentrations of L cockerels were, respectively, 160% greater and 32% less than those of N cockerels. In addition, plasma B clearance rate of L birds was 85% greater than that of N birds, thus suggesting a greater B secretion rate in L birds. However, maximal plasma CBC of L cockerels was 59% less than that of N cockerels. Thus, the free plasma B concentration of L birds was greater than that of N birds. The increase in the plasma B concentration of L cockerels is explained in part by the relative adrenal weight of these birds which was 88% greater than that of N cockerels. In addition, there were differences at the adrenocortical cell level. On an equal cell concentration basis, basal and maximal B production values (stimulated by ACTH analogs and 8-Br-cAMP, and supported by 25-hydroxycholesterol) of L cockerel adrenocortical cells were, respectively, 73% and 139% greater than those of N cockerel adrenocortical cells. In addition, maximal ACTH-induced aldosterone production of L bird cells was 104% greater than that of N bird cells, such that the ratio of aldosterone production to B production was not altered by protein deprivation. The data suggest that the greater steroidogenic capacity of L cockerel cells was due to an increase in intracellular steroidogenic enzyme content and/or activity and not to an alteration in the composition of adrenocortical cell types within the populations of isolated cells. Furthermore, ACTH analog ED50 values for B, aldosterone, and cAMP production by L bird cells were about one third to one fifth the values for N bird cells, thus indicating that L bird cells were about 3-5 times more sensitive to ACTH than were N bird cells.(ABSTRACT TRUNCATED AT 400 WORDS)

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1988

Protein malnutrition in the domestic fowl induces alterations in adrenocortical cell adrenocorticotropin receptors.

Our previous work suggests that persistent protein malnutrition in immature domestic fowl (Gallus gallus domesticus) alters ACTH-adrenocortical cell interaction, possibly including ACTH receptors. To investigate this possibility, we measured some ACTH receptor parameters in isolated adrenocortical cells from normal and dietary protein-restricted domestic fowl. White Leghorn cockerels (2 weeks old) were fed isocaloric semipurified diets containing either 8% [low (L)] or 20% [normal (N)] soy protein for 4 weeks ad libitum. Cockerels were quickly killed by decapitation and exsanguination, and adrenal glands were removed and prepared for cell isolation. Highly enriched (greater than 80% pure) adrenocortical cells (collagenase isolated, followed by separation on a Percoll continuous density gradient) were evaluated for ACTH receptors using pharmacological and radioligand approaches. In a pharmacological approach, we measured the influence of the complete, competitive antagonist, human (h) ACTH-(7-38) on hACTH-(7-39)-induced corticosterone production by adrenocortical cells from L and N cockerels. Inhibitor constants of hACTH-(7-38), calculated from Schild plots, were 3.16 X 10(-7) and 9.82 X 10(-7) M for L and N cockerel cells, respectively, thus suggesting differences in ACTH receptor function between the two treatment groups. To characterize ACTH receptors directly, we measured the binding of a monoiodinated ACTH analog [125I-Tyr23]hACTH-(1-39) to domestic fowl adrenocortical cells. Binding was linear with cell concentration, highly specific (only ACTH peptides caused significant displacement), rapid (maximal binding by 1 h), reversible (half-time of dissociation, approximately 40 min), and saturable. Curvilinear Scatchard plots were obtained, and vectorial analysis resolved both high and low affinity sites. The concentrations (femtomoles per 50 micrograms DNA) and dissociation constants (Kd) of both classes of sites were different between N and L bird cells. Values of these receptor parameters for N and L cockerel cells were, respectively, as follows: concentrations of low affinity sites, 7.45 and 11.60; concentrations of high affinity sites, 3.16 and 5.50; Kd of low affinity sites, 2.05 X 10(-8) and 2.58 X 10(-9) M; Kd of high affinity sites, 1.01 X 10(-9) and 1.27 X 10(-10) M. Thus, the overall binding capacity of L bird cells was 65% greater than that of N bird cells. In addition, the overall affinity (1/Kd) of sites of L bird cells was 9 times that of sites of N bird cells. These data indicate that persistent protein malnutrition in the domestic fowl increased both the number and affinity of adrenocortical cell ACTH receptors.

Adrenal Cortex↗
PubMed1988

Nonconventional yeasts: their genetics and biotechnological applications.

To date, more than 500 species of yeasts have been described. Most of the genetic and biochemical studies have, however, been carried out with Saccharomyces cerevisiae. Although a considerable amount of knowledge has been accumulated on fundamental processes and biotechnological applications of this industrially important yeast, the large variety of other yeast genera and species may offer various advantages for experimental study as well as for product formation in biotechnology. The genetic investigation of these so-called unconventional yeasts is poorly developed and information about corresponding data is dispersed. It is the aim of this review to summarize and discuss the main results of genetic studies and biotechnological applications of unconventional yeasts and to serve as a guide for scientists who wish to enter this field or are interested in only some aspects of these yeasts.

Biotechnology↗
PubMed1988

[Venous thrombectomy: indications, technic and results].

Venous thrombectomy is a promising approach to treating acute iliofemoral thrombosis with comparable results to those of thrombolysis. It is the treatment of choice in cases of thrombosis caused by pregnancy, delivery, surgery (early postoperative period) and trauma. The success depends on the age of the thrombus, skilled surgical techniques with atraumatic preparation and intra-operative endoscopic control. Creation of an adjunctive av-fistula is mandatory to protect against reocclusion. Followup includes X-ray and checkups. Reininterventions are possible.

Humans↗
PubMed1988

Pharmacokinetics of nisoldipine. I. Absorption, concentration in plasma, and excretion after single administration of [14C]nisoldipine in rats, dogs, monkey, and swine.

The absorption, disposition and excretion of (+/-) 3-isobutyl-5-methyl 1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-pyridine-3,5-dicarboxylate (nisoldipine, Bay k 5552) have been studied following a single administration of the 14C-labelled compound to rats, dogs, monkey and swine via different routes (intravenous, oral, intraduodenal) in the dose range of 0.05-10 mg.kg-1. [14C]nisoldipine was absorbed rapidly and almost completely. Peak concentrations of radioactivity in plasma were reached 0.9 h (rat), 1.4 h (dog), and 3.6 h (monkey) after oral administration with normalized maximum concentrations being in the same range for all three species (0.49-0.79). The radioactivity was eliminated from plasma with half-lives between 42 h and 54 h within an observation period up to 3 days. The contribution of unchanged [14C]nisoldipine to the concentration of total radioactivity in plasma was low after oral administration (between 0.5% (monkey) and 3.4% (dog) in the peak) indicating an extensive presystemic elimination of this compound. The bioavailability was estimated at 3.4% in rats and 11.7% in dogs. [14C]nisoldipine was highly bound to plasma proteins with free fractions of 0.9-2.9%. The excretion of the radioactivity via urine and feces/bile both after oral and intravenous administration of [14C]nisoldipine occurred rapidly and almost completely within 48 h in all species. Very small residues in the body were recovered at the end of the experiments in rats and dogs (less than 1.6% of the dose). The biliary/fecal route of excretion was preferred in rats, dogs and swine, whereas in monkey 76% of the dose was excreted renally.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1988

Pharmacokinetics of nisoldipine. II. Distribution to and elimination from tissues and organs following single or repeated administration of [14C]nisoldipine to rats and dogs.

(+/-) 3-Isobutyl-5-methyl 1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-pyridine-3,5-dicarboxylate (nisoldipine, Bay k 5552) labelled with 14C was administered to male rats, pregnant and lactating rats as well as female dogs with single intravenous (1.0 or 0.5 mg.kg-1) or oral doses (5 mg.kg-1) and with repeated oral doses of 5 mg.kg-1 to male rats for 3 weeks. The distribution to organs and tissues, the placental transfer and the secretion into milk was studied using whole body autoradiographic methods and/or quantitative determination of total radioactivity after autopsy, [14C]nisoldipine was distributed rapidly and heterogenously to organs and tissues. In the initial distribution phase following intravenous administration high concentrations compared to blood were found in heart muscle, brain, lung, adrenal cortex, kidney, and the intestinal mucosa. After single oral administration and at later time points after intravenous administration only liver and kidney contained higher radioactivity concentrations compared to plasma. Elimination from most of the organs occurred quite uniformly with half-lives of 40-70 h. There was no indication for distinct differences in the distribution pattern between rats and dogs. Following a 21-day oral treatment of male rats the equivalent concentrations in most of the tissues were increased by factors of 5 to 11. This factor was higher in the adrenal gland (15) and adipose tissue (19). The residues in the body after repeated administration were eliminated with a terminal half-life of about 10 days. No indication was found for a distinct retention of substance-associated radioactivity in organs and tissues.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1988

The pharmacokinetics of nitrendipine. I. Absorption, plasma concentrations, and excretion after single administration of [14C]nitrendipine to rats and dogs.

[14C]nitrendipine (3-ethyl 5-methyl 1,4-dihydro-2,6-dimethyl-4-(3-nitrophenyl)-3,5-pyridine dicarboxylate, Bay e 5009, Baypress, Bayotensin) was administered to rats and dogs (intravenously, orally, intraduodenally, 0.5-50 mg/kg) in order to investigate absorption, disposition, and excretion of parent compound and metabolites. The absorption of radioactivity following oral administration of [14C]nitrendipine was rapid and almost complete in both species. Maximum concentrations of total radioactivity in plasma were reached after 1.2 (rat) or 0.7 h (dog). The radioactivity was eliminated from plasma with terminal half-lives of 57 (rat) and 188 h (dog) during an observation period up to 10 and 9 days, respectively. Unchanged nitrendipine contributed to the AUC of total radioactivity only 8-9% after intravenous and 1-2% after oral administration. The bioavailability of nitrendipine after oral administration amounted to 12% in rats and 29% in dogs due to a strong first pass elimination process. About two thirds of the radioactivity administered were excreted via faeces, one third via urine. Distinct sex-differences in the excretion pattern could be found in rats but not in mice. They were attributed to well-known sex differences of the metabolic capacities in rat liver. In rats the radioactivity excreted via bile (about 75% of the dose) was subject to a marked entero-hepatic circulation, about 50% of the amount excreted being reabsorbed. The radioactive residues in the body were low (0.5% of the dose after 2 days in rats; less than or equal to 0.6% after 9 days in dogs).

Absorption↗
PubMed1988

[Possibilities for ambulatory pediatric surgery in the district hospital].

Primary surgical care for children generally comes under the responsibility of the hospital at district level. Selected surgical problems of children may be exclusively handled on an outpatient basis under certain conditions relating to personnel, space, and equipment. The recommendation of expansion of outpatient paediatric surgery seems to be justified by experience so far obtained from 485 cases. Shorter waiting periods, relief on hospital bed capacity, and prevention of possible damage due to hospitalisation are noteworthy advantages of the approach.

Adolescent↗