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Biomedical subjects

S Christensen

Publications and source records attributed to S Christensen.

At least 199 records · Page 11Linked to original sources
PubMed1978

Dissociation between antidiuretic response and renal medullary cyclic AMP levels in the rat.

In vivo experiments were performed in male Wistar rats to elucidate the probable relation between renal concentrating ability and medullary cyclic AMP content as influenced by changes of hydration and by administration of antidiuretic hormone (ADH). Cyclic AMP levels were 37% lower in water diuretic than in control animals (P less than 0.01), but were not significantly changed during prolonged antidiuresis induced by dehydration or ADH administration. Nor could any change of cyclic AMP levels be demonstrated between 2 and 20 min after ADH injection. Significant increases of medullary cyclic AMP content occurred following stress, anesthesia, and administration of isoproterenol and 3-isobutyl-1-methylxanthin. The results suggest that the level of cyclic AMP in the renal medulla may not be an important determinant of the antidiuretic response produced by ADH in rats.

Animals↗
PubMed1978

Uptake of labelled free and esterified cholesterol from plasma by the aortic intima--media tissue measured in vivo in three animal species.

Hyperlipemic stilboestrol-treated cockerels, cholesterol-fed rabbits and minipigs, as well as normolipemic cockerels and rabbits were injected intravenously with homologous plasma of corresponding lipid concentration labelled in vivo with radioactive cholesterol. The ratios between labelled free cholesterol and labelled esterified cholesterol in the intima--media from the thoracic aorta of these 5 groups of animals were respectively 1-, 2-, 8-, 2- and 20-fold greater than the corresponding average tracer ratio in plasma during the uptake period of 4--6 h. The intima--media tissue in the coronary arteries studied in one minipig contained 2--5 times more labelled cholesterol per mg wet weight than corresponding aortic tissue. This arterial uptake of labelled cholesterol in the minipigs was measured concomitantly with the uptake of phosphatidylcholine and plasma protein labelled in vivo. The uptake for these various tracers in the minipig suggested entry of labelled free and esterified cholesterol into the arterial wall, mainly as part of the plasma lipoproteins, with subsequent hydrolysis in the arterial wall of some of the cholesterol ester. In the stilboestrol-treated cockerels hydrolysis of cholesterol ester seems to be absent. The relatively higher uptake in the minipig of the labelled plasma protein (albumin) than of the lipoprotein (as traced by its lipids) suggests a molecular weight-dependent arterial entry of these plasma macromolecules.

Animals↗
PubMed1978

Factor VIII procoagulant activity in children with nephrotic syndrome and post-streptococcal glomerulonephritis.

Plasma factor VIII procoagulant activity has been shown to be significantly elevated in 32 children with the nephrotic syndrome. This increase is more marked in those with obvious glomerular lesions on histology than in patients with minimal change nephropathy. Fluctuations in factor VIII levels corresponded to changes in the clinical condition of the nephrotic syndrome. In 28 children with post-streptococcal glomerulonephritis, 4 patients with the highest factor VIII levels recovered between 7 and 60 days of onset of disease whereas the remainder did so in less than 7 days. Factor VIII levels may reflect the extent of immunopathological injury to glomerular capillaries and be useful in management of children with glomerular disease.

Blood Coagulation↗
PubMed1977

A simple and inexpensive protein binding assay for cyclic AMP in biological materials.

We have developed a simple and inexpensive method for largecapacity cAMP determination in biological materials. The assay is based on competitive binding of 3H-cAMP to proteins isolated from rabbit skeletal muscle. Bovine serum albumin is added to the incubate to reduce non-specific interference. Separation of free and bound radioactivity is performed by (NH4)2SO4 precipitation allowing determination of either free or bound fraction. In the latter case, all procedures are performed in the same tube, to which is finally added 1.2 ml of scintillation fluid for counting. By this only one fourth. The method has been applied to rat tissue extracts and urine with satisfactory sensitivity, precision and accuracy.

Ammonium Sulfate↗
PubMed1977

Antidiuretic and urinary cyclic AMP response of vasopressin in normal rats and in rats with lithium-polyuria.

The antidiuretic and urinary cyclic AMP response to supramaximal vasopressin infusion was studied in normal rats and in rats with lithium-polyuria. The animals were anaesthetized and then infused with a solution designed to produce excessive water diuresis and to lower basal cyclic AMP excretion. In 6 control animals not infused with vasopressin (1) urinary cyclic AMP excretion decreased during the infusion period. Vasopressin infusion (300 muU/min.) consistantly induced antidiuresis in all of 13 control rats (II); but the urinary cyclic AMP response varied individually from a significant increase in 6 animals to either no change or to a decrease in the remaining animals. The antidiuretic response to vasopressin was inhibited by 85% in 10 animals with marked polyuria induced by lithium administration (III). None of the animals in this group showed a significant increase of cyclic AMP excretion in response to vasopressin. The average rate of cyclic AMP excretion, which was equal in the two groups before vasopressin, was signifimantly lower in group III than in group II during vasopressin infusion. It is suggested that the increase in cyclic AMP excretion during vasopressin antidiuresis, although not consistant, most likely reflects hormone-induced changes of intracellular cyclic AMP levels in the renal medulla. Thus, the data suggest that the nephrogenic diabetes insipidus syndrome produced by lithium is associated with a defect in the renal formation of cyclic AMP in response to vasopressin.

Animals↗
PubMed1976

Lower extremity amputations in the county of Aalborg 1961-1971. Population study and follow-up.

All lower extremities amputations in the county of Aalborg, Denmark, during the period 1961-1971 were analysed. During this 10-year period the amputation rate did not increase. Those requiring amputation were predominantly arteriosclerotics followed by diabetics. The diabetics underwent amputation 3 years younger on average than the arteriosclerotics, but it was more often possible to preserve the knee in diabetics. There was a far higher rate of successful prosthetic fitting among patients in whom the knee had been preserved. Despite a high mortality, also beyond the first postoperative months, prosthetic fitting was of such psychological and social value, that every effort should be made to amr homes. This was the most positive finding in the present study.

Aged↗
PubMed1976

Variations in intra-oral stimulation and nutritive sucking.

Sucking records were made from 24 infants, aged 3-4 days, fed small amounts of their usual formula from nipples of different sizes (5/16-, 8/16-, and 11/16-inch diam). Polygraphic and observer measures showed that the large nipple elicited fewer sucks and a slower sucking rate; 5 infants seen on 2 successive days showed a more marked nipple preference on the second day. The results show that intra-oral stimuli control sucking for a nutriment in much the same way as they have already been shown to control nonnutritive sucking.

Bottle Feeding↗