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T Knudsen

Publications and source records attributed to T Knudsen.

25 records · Page 2Linked to original sources
PubMed1989

The mode of inhibition of the Na+-K+ pump activity in mast cells by calcium.

1 The inhibition by calcium of the Na(+)-K+ pump in the plasma membrane of rat peritoneal mast cells was studied in pure populations of the cells by measuring the ouabain-sensitive uptake of the radioactive potassium analogue, 86rubidium (86Rb+). 2 Exposure of the cells to calcium induced a time- and concentration-dependent decrease in the ouabain-sensitive K+(86Rb+)-uptake of the cells without influencing the ouabain-resistant uptake. The development of the inhibition required the presence of potassium in the medium in the millimolar range (1.5-8.0 mM), and it did not occur at a concentration of potassium (0.24 mM) that is probably rate limiting for the pump activity. In the presence of 1 mM calcium full inhibition developed almost immediately and was not readily reversed. The inhibition was not significantly reduced by 15 min incubation with 1.2 mM EGTA. 3 The inhibitory action of calcium did not develop when the mast cells were incubated in a potassium-free medium, which is known to block Na(+)-K+ pump activity and allow accumulation of sodium inside the cells. Likewise, increasing the sodium permeability of the plasma membrane by monensin abolished the inhibition of the pump activity. In both cases, incubation of the cells with 4.7 mM potassium and tracer amounts of 86Rb+ resulted in a very large uptake of K+ (86Rb+) into the cells (up to 2 nmol per 10(6) cells min-1), indicating a high activity of the Na(+)-K+ pump. 4. These observations support the view that long-term incubation of rat peritoneal mast cells in a calcium-free medium increases the permeability of the plasma membrane to sodium, and the consequent increase in the intracellular concentration of sodium causes an increase in the activity of the pump. Addition of calcium to the cell suspension decreases the sodium permeability, and hence the pump activity. This hypothesis is supported by the stimulation of pump activity produced by monensin, which is not inhibited by calcium. The enhancement of pump activity after exposure of calcium-deprived cells to EGTA might be the result of a further increase in the sodium permeability of the plasma membrane.

Animals↗
PubMed1985

Rubidium uptake of mononuclear leukocytes from normotensive and borderline hypertensive first degree relatives to patients with essential hypertension.

Uptake of 86Rubidium of mononuclear leukocytes (MNL) was used as a measure of cellular sodium-potassium pump activity. 86Rb-uptake was determined with the pump stimulated mainly from inside the cells by sodium as well as with a combined stimulation from inside by sodium and from outside by Rb. In the first case there was an increased pump activity in MNL from borderline hypertensive offspring of hypertensive patients (BHO), and this may be related to an increased number of pump sites observed previously (10). Estimation of maximal pump activity (Vmax) of MNL suggested that Vmax of each pump site in MNL from BHO may be decreased compared to control value of MNL from healthy normotensive subjects.

Humans↗
PubMed1983

Improvement of physical capacity after long-term training in patients with chronic active hepatitis.

A training program was started in nine patients with chronic active hepatitis in clinical remission while receiving immunosuppressive therapy. The patients were examined before and after a training period of 4-5 weeks and 10-12 weeks, respectively. The calculated oxygen consumption increased by 19% and 29%, and the estimated work load capacity improved. No change occurred in alanine aminotransferase, aspartate aminotransferase, alkaline phosphatases, gamma-glutamyl-transpeptidase, serum bilirubin, or prealbumin, whereas creatine kinase and lactate dehydrogenase increased significantly. The clinical condition did not worsen in any patient, and most of the patients felt that their physical performance capacity had improved. We conclude that long-term regular physical training is well tolerated by patients with chronic active hepatitis in clinical remission and that training leads to improvement in the oxygen consumption and the estimated work load capacity in such patients.

Adolescent↗
PubMedDate not supplied

Community health workers in national programmes: the case of the family welfare educators of Botswana.

Community health worker programmes have become a prominent feature of many primary health care schemes in developing countries. This paper, which is based on a larger collaborative study undertaken in 3 countries, focuses on the experiences with such workers in Botswana, and concludes that many of the key issues that were highlighted in the Botswana study are similar to those in other countries. These can be summarized under four headings: unrealistic expectations, poor initial planning, problems of sustainability, and the difficulty of maintaining quality of care. The future success of these workers will depend on their being integrated more systematically into local services, with concomitant strengthening of management support and supervision.

Botswana↗