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K F Petersen

Publications and source records attributed to K F Petersen.

At least 55 records · Page 3Linked to original sources
PubMed1990

Effect of dietary protein on the capacity of urea synthesis in rats.

The in vivo capacity of urea nitrogen synthesis (CUNS) during alanine stimulation was measured within the blood amino acid concentration interval 7.3-11.6 mmol/l, where urea synthesis is at maximum and independent of substrate concentration. Three groups of rats were fed for 14 days, either a low protein diet (8%), a normal diet (17%), or a high protein diet (53%). Diet protein modified both CUNS and plasma glucagon concentration. CUNS was 5.86 +/- 2.93, 7.43 +/- 2.16, and 19.31 +/- 4.32 mumol/(min.100 g BW) (mean +/- SD, N = 6), respectively. The corresponding plasma glucagon concentrations after alanine stimulation were 222 +/- 400, 633 +/- 229, and 1700 +/- 627 ng/l, respectively. The in vivo kinetics of urea production is regulated by dietary protein, possibly via glucagon. This implies that the liver plays an active part in adaptation of whole body nitrogen homeostasis to dietary changes.

Alanine↗
PubMed1987

Time dependent stimulating effect of glucagon on the capacity of urea-N synthesis in rats.

The effect of glucagon on the capacity of urea-N synthesis was examined in 24 rats as a function of time. First, the conditions for saturation of urea synthesis under glucagon influence were studied by the kinetics of urea-N synthesis rate in relation to arterial blood alpha-amino-N concentration between 5 and 17 mmol/l in 21 nephrectomized rats given zinc-glucagon (20 micrograms s.c. per day) for 14 days. Alanine was infused so that steady state concentrations of total alpha-amino-N was attained in each rat. The urea-N synthesis rate was calculated as accumulation in total body water corrected for intestinal hydrolysis. The relationship suggested a barrier limited substrate inhibition kinetics, as earlier found in control rats, and data were examined accordingly by non-linear regression analysis. The estimated kinetic constants were: Vmax = 71 mumol/(min X 100 g body wt), Km = 5.4 mmol/l, Ki = 2.4 mmol/l, and the barrier = 4.4 mmol/l. Vmax was increased three times compared with controls. The capacity of urea-N synthesis, i.e. the zenith of the relation, was attained in the concentration interval 7.5 to 12.0 mmol/l, as in controls. The capacity of urea-N synthesis was determined during i.v. infusion of zinc-glucagon (0.15 microgram per min) and after 2, 8, and 14 days of daily s.c. injections of 20 micrograms zinc-glucagon. Rats given zinc-protamine solution were controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Hepatic regeneration following glucagon treatment.

Liver regeneration was studied as a function of time after suppression of the normal glucagon response. Rats were given a daily subcutaneous injection of 20 micrograms zincglucagon for 14 days, whereafter a 70% hepatectomy was performed. In the glucagon treated rats the rise in plasma glucagon concentration was diminished after hepatectomy. At intervals from 12 to 384 hours after hepatectomy, the gain in liver weight, the hepatic DNA content, and the antipyrine clearance were measured. All 3 variables were found to be significantly higher in animals with diminished glucagon response. The results indicate that prevention of the normal increase in glucagon concentration leads to signs of increased liver regeneration after 70% hepatectomy.

Animals↗
PubMed1986

Increased capacity of urea synthesis in streptozotocin diabetes in rats.

Diabetes was induced in Wistar rats by intravenous streptozotocin, 75 mg/kg. Four and 14 days after streptozotocin, fasting insulin decreased to about one-third, and fasting glucagon increased three-fold. The urea-N synthesis rate, stimulated by infusion of alanine, was measured at different amino acid concentrations 14 days after streptozotocin in 24 rats. The relationship was compatible with a barrier limited substrate inhibition kinetics. Data were examined accordingly by non-linear regression analysis. Among the estimated kinetic constants, only the 70% increase in Vmax was different from control values. In control rats the capacity of urea nitrogen synthesis, as measured within the amino acid concentration interval 7.3-11.6 mmol/l, was 10.2 +/- 1.1 mumol . (min 100 g BW)-1 (mean +/- SEM). The capacity was not different in 4 day diabetic rats, whereas it doubled in 14 day diabetic rats, 20.9 +/- 1.7 mumol (min 100 g BW)-1. The alanine elimination rate was 35% higher in the 14 day diabetic rats compared both to 4 day diabetic and control rats. The increase of urea synthesis is suggested to be due to enzyme induction by glucagon. The net nitrogen balance was negative at amino acid concentrations up to 25 mmol/l, indicating that the urea synthesis was increased at the expense of amino nitrogen.

Animals↗
PubMed1983

Methods for internal quality control in the mycobacteriology laboratory.

A proposal is given for internal quality control in the mycobacteriology laboratory by continuously monitoring the yields of positive results in microscopy and culture as well as the contamination rates of the culture media. The figures thus obtained can be processed as is customary done in clinical chemistry in order not only to detect deviations, but also to discern whether they are due to chance or whether they indicate a change in the quality of performance. Some examples are given to illustrate the possibilities offered by this control system.

Culture Media↗
PubMed1983

[Mycobacteria].

Explore the source record for details and available documents.

Humans↗
PubMed1980

[Resistance of Haemophilus influenzae to antibiotics in the Federal Republic of Germany (author's transl)].

In a multi-center study 523 strains of H. influenzae and H. parainfluenzae isolated from patients in eight towns of the Federal Republic of Germany were tested for their sensitivity to 15 different chemotherapeutic agents. 1.7% of the strains were resistant to ampicillin, 1,5% to chloramphenicol and 2.5% to tetracycline. All ampicillin-resistant strains produced beta-lactamase. For the first time, multiple resistant strains were isolated: two against ampicillin, chloramphenicol and tetracycline; one in addition also against co-trimoxazole. It is likely that there will be a spread of such resistant strains.

Ampicillin↗
PubMed1978

[Pharmacokinetics of rifampicin in gastrectomized persons (author's transl)].

A laboratory method was developed whereby the presence of Rifampicin in the blood is determined microbiologically by means of a diffusion test. The organism used was Sarcina lutea. The tests established that the Rifampicin levels in the blood of pylorogastrectomized persons were significantly higher then they were in a normal control group. The daily changes in the Rifampicin levels were simulated and checked by analogue computer. The findings indicated that the increased absorption in gastrectomized persons cannot be due to accelerated passage and that it is presumably attributable to chemical and physical factors. The results are analysed statistically and summarized in graphs.

Gastrectomy↗