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Biomedical subjects

K Christensen

Publications and source records attributed to K Christensen.

At least 217 records · Page 12Linked to original sources
PubMed1983

A contractile ring-like mechanism in wound healing and soluble factors affecting structural stability in the cortex of Xenopus eggs and oocytes.

Holes or tears have been made in the surface of unfertilized Xenopus eggs or oocytes in various buffered media and the surface response to the wound has been observed with the light microscope. In the presence of calcium ion in the medium, a pigmented ring appears around the wound and constricts in purse-string fashion until the hole is closed. A highly pigmented scar remains. We show that the surrounding pigmented cortex is moved over the denuded cytoplasm when wound healing closes a large excision wound in the pigmented surface. This movement of surface is consistent with a model of a purse string, closing the hole by pulling existing surface over the denuded cytoplasm. The presence of cytochalasin B in the medium inhibits wound healing completely. The sensitivity to the antibiotic is similar to that of the contractile ring in cytokinesis. Wounds made in the surface of ripe ovarian oocytes do not heal in the presence of calcium ion. The healing mechanisms, or their sensitivity to calcium, thus appear during meiotic maturation or ovulation. The egg cortex and membrane around wounds dissociate in the absence of calcium or in the presence of cytochalasin B. The cell cortex of oocytes also dissolves around wounds even in the presence of calcium. This cortical dissolution will not occur in the isolated cortex and thus requires soluble cytoplasmic factors. Models are proposed to explain these observations.

Animals↗
PubMed1982

Studies on growth, nitrogen and energy metabolism in rats.

Feed intake, growth, nitrogen retention and energy metabolism were measured in 12 male Wistar rats fed ad lib. for 14 weeks with non-purified diets. The feed intake increased rapidly in 4 weeks time from 16 g/d to 25 g/d, and then it was constant in the following 10 weeks. In relation to metabolic live weight the energy intake decreased from about 1400 to 800 kJ GE/kg0.75. With the high intake of energy the growth curve obtained is assumed to be near maximum level. The curve can be transformed to a linear one based on log days expressed as y, LW, g = -836 + 594 X log days with CV = 7.5% and r2 = 0.968. The nitrogen retention increased from 200 to 300 mg N/d in period III when the rats 60 days old, and then it decreased in the following 10 weeks to about 100 mg N/d. In relation to metabolic live weight nitrogen retention is assumed to be near maximum level, decreasing from 1100 to 200 mg N/kg0.75. In the live weight range from 100 to 350 g the total energy retention (RE) increased from about 65 to 125 kJ/d, corresponding to 36% of ME. The energy retained in "protein" increased from 30 to 45 kJ/d, and then it decreased to about 25 kJ/d, while the energy retained in "fat" increased steadily from about 30 to 100 kJ/d in the live weight range from 100 to 350 g. Thereby the ratio between energy retained in "protein" or "fat" decreased from 1:1 to 1:4.

Aging↗
PubMed1982

Yersinia enterocolitica infections and chronic connective tissue diseases.

The purpose of the investigation was to evaluate a possible relationship between infection with Yersinia enterocolitica and chronic connective tissue diseases. 258 patients with a positive faeces culture in the years 1972-75 were examined in 1978 with regard to the presence of chronic connective tissue diseases. The investigation, which was carried out primarily by a questionnaire followed up by a clinical examination of "the questionnaire-positive" patients, did not reveal any causative relationship between earlier Y. enterocolitica infections and chronic connective tissue diseases.

Adolescent↗
PubMed1982

The reflex dystrophy syndrome response to treatment with systemic corticosteroids.

Twenty-three patients with reflex dystrophy syndrome were randomly allocated to medication with oral prednisone, 10 mg thrice daily, or placebo, previous reports having indicated effect of systemic corticosteroids. The medication was continued until clinical remission, maximally 12 weeks. The diagnosis was based on fulfillment of at least four of seven criteria which included clinical, radiological and circulatory changes. All 13 patients in the prednisone-treated group showed more than 75% clinical improvement within the twelve-week period. Of the ten patients who received placebo, only two reported improvement. Prednisone appears to be superior to other treatment in reflex dystrophy syndrome, although the mode of action is not known.

Administration, Oral↗
PubMed1982

Insensitivity to cytochalasin B of surface contractions keyed to cleavage in the Xenopus egg.

In fertilized eggs of Xenopus laevis a marked flattening of the pigmented animal hemisphere has been observed. The flattening begins 15-20 minutes before the appearance of the cleavage furrow. As the furrow develops, the pigmented surface relaxes and rounds up. The initial appearance of the furrow is thus shown to be a combination of furrow deepening and rounding up of adjacent pigmented surfaces. It is demonstrated that the flattening is not caused by gravity or osmotic mechanisms and that internal pressure is increased during the flattening. The flattening is interpreted to be an isodiametric contraction of the pigmented surface. The contraction is not inhibited by injected cytochalasin B in sufficient concentrations to completely inhibit cleavage furrow formation. These results are discussed with respect to the presence of two surface contractile systems, distinguishable on the basis of their differing sensitivity to cytochalasin B.

Animals↗
PubMed1982

Phantom breast syndrome in young women after mastectomy for breast cancer. Physical, social and psychological aspects.

Phantom breast syndrome (PBS) developed in 11 out of 31 (35.5%) consecutive young women, who had undergone mastectomy for breast cancer. Six to 21 months after operation the patients were asked to take part in a follow-up investigation in which physical sequelae, social condition, and psychological reactions were assessed and related to the presence of PBS. There was no correlation between PBS and postsurgical physical sequelae, those who had received adjuvant radiotherapy, or the side on which mastectomy was performed. Socially, the group with PBS was dominated by women with an occupation outside the home. The psychological examination showed that the group with PBS had a definite predominance of women with a severely damaged body image and impaired sexual function in comparison to the group without PBS. However, the predominance did not reach a statistically significant level. Sexual identity, anxiety, affective disorder or changes in close family relationships did not reveal any distinct pattern. In our opinion, the appearance of PBS should be seen in relation to complex psychological reactions to the mastectomy.

Adult↗
PubMed1981

In vitro evaluation of porcine lymphocyte response to phytohaemagglutinin using a modified "whole blood" technique.

The purpose of these investigations was to develop a modified whole blood technique for measuring quantitatively the responsiveness of pig peripheral blood lymphocytes to phytohemagglutinin (PHA) in vitro. Washed blood cells from a fixed volume of blood were suspended in culture medium supplemented with foetal calf serum and stimulated with a pure mitogenic PHA preparation. The stimulation was measured by the incorporation of 3H-thymidine. Data are presented to show the effect of different variables on the culture system. The transformation response was measured at different levels of PHA and the reproducibility of the different responses from repeated investigations was used to evaluate the usefulness of the test. The best reproducibilities of the stimulation response were found at the high PHA concentrations. Also the calculated PHA concentration giving maximum stimulation response had a relatively high reproducibility and indicates that this value is a convenient and reliable alternative measure of the functional capacity of the lymphocytes.

Animals↗
PubMed1981

Genetic studies on the in vitro PHA-transformation of porcine blood lymphocytes.

The response of pig peripheral blood lymphocytes to phytohaemagglutinin (PHA) was studied by a whole blood technique. The material for study comprised 441 offspring from one generation of a randomly mated Danish Landrace pig herd. The pigs were blood-sampled at a weight of 90 kg. After correlation for influence from other blood cells and for seasonal variation, the heritability of the PHA stimulation responses at different PHA concentrations were estimated. The heritability estimates ranged from 0.15 to 0.53. Also the PHA concentration giving maximum stimulation response, as calculated by a dose response function, was found to vary depending on genetic variation among the pigs with an estimated heritability of 0.38.

Animals↗
PubMed1981

Decreased insulin removal contributes to hyperinsulinemia in obesity.

Peripheral plasma insulin and C-peptide concentrations during oral glucose tolerance tests were measured in 7 severely obese and 12 normal weight nondiabetic subjects. The insulin and C-peptide levels as well as incremental areas under the plasma curves were 2--5 times higher in the obese subjects (P less than 0.05). The C-peptide to insulin molar ratios as well as the relation between incremental areas under the plasma curves of the two peptides were used as relative measures of the hepatic insulin extraction. They were both reduced in the obese subjects, which suggests that decreased insulin removal may contribute to the hyperinsulinemia of obesity. Sixty minutes after the oral glucose load, all of the obese patients had higher peripheral venous insulin concentrations compared with those found in normal subjects with similar C-peptide levels. This suggests that the reduced insulin extraction is not entirely explained by increased beta-cell secretory activity, but is also a specific consequence of obesity.

Blood Glucose↗