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Biomedical subjects

T Johansen

Publications and source records attributed to T Johansen.

At least 127 records · Page 7Linked to original sources
PubMed1983

Plasma catecholamine and serum gastrin concentrations during sham feeding.

Plasma adrenaline, plasma noradrenaline and serum gastrin concentrations were measured before and after sham feeding in eight patients with duodenal ulcer and in four normal subjects. No significant change in the concentrations was observed after sham feeding. In three patients with duodenal ulcer an insulin test resulted in a 25-fold rise in plasma adrenaline. The ulcer patients showed significantly higher levels of plasma adrenaline and plasma noradrenaline than the normal subjects both before and after sham feeding, and this difference was probably not caused only by age difference in the two groups. It is concluded that sympathetic nervous activity and serum gastrin concentrations are not influenced by sham feeding in contrast to the influence of insulin hypoglycemia.

Adult↗
PubMed1983

Ouabain-binding and 86rubidium-uptake in lymphocytes of normal and borderline hypertensive subjects.

In borderline hypertensives cellular sodium concentration seems to be increased, indicating that cellular abnormalities are present in the early course of essential hypertension. In order to study the mechanisms underlying this finding the number of sodium/potassium pump sites and the cation pump activity were studied in lymphocytes of nine borderline hypertensives (27 (20-36) years) and nine controls (28 (20-36) years). Maximum 3H-ouabain binding and 86Rb-uptake were taken as measures of the number of pump sites and cation pump activity, respectively. The median number of sodium/potassium pump sites was 49.6 X 10(3) molecules/cell in the BH group compared to 32.4 X 10(3) in the control group (P less than 0.01). Median 90 min 86Rb-uptakes were 54.0 pmol/10(6) cells in BH subjects and 39.4 in controls (P less than 0.10). The increased number of sodium/potassium pump sites and the tendency to increased cation pump activity in lymphocytes of BH subjects in vitro may be interpreted as an adaptive change possibly induced by a circulating natriuretic substance.

Adult↗
PubMed1983

Utilization of adenosine triphosphate in rat mast cells during and after secretion of histamine in response to compound 48/80.

The adenosine triphosphate (ATP) content of rat mast cells and their lactate production were measured during and after secretion of histamine induced by compound 48/80. Antimycin A and oligomycin were used to block oxidative ATP synthesis, and 2-deoxyglucose (2-DG) was used to block glycolytic ATP synthesis. Histamine secretion was completed after 10 sec. exposure of the cells to compound 48/80. During that time period there was an increased ATP-utilization of 0.15 pmol/10(3) cells. After completion of the secretory process there seemed to be an enhanced utilization of ATP of 0.40 pmol/10(3) cells/min., which may be associated with recovery of the cells.

Adenosine Triphosphate↗
PubMed1983

Affinity of drugs for cytochrome P-450 determined by inhibition of p-nitrophenetole O-deethylation by rat liver microsomes.

The rate of conversion of p-nitrophenetole to p-nitrophenol by rat liver microsomes was studied. Inhibition of the reaction by CO and by SKF 525A and the absolute dependence on NADPH and oxygen indicate that cytochrome P-450 catalyzes the reaction. The apparent Km for oxygen was 0.07 microM. Furthermore, cytochrome b5 seemed to be involved in the formation of p-nitrophenol. The effect on p-nitrophenol formation of drugs known to be involved in drug interaction in clinical practice was studied. There was a competitive inhibition by phenytoin (inhibitor constant, Ki, 30 microM), disulfiram (Ki, 2 microM) and chloramphenicol (Ki, 20 microM), whereas a mixed-type inhibition by isoniazid was observed (Ki, 1,3 mM and Kii, 10,6 mM).

Animals↗
PubMed1983

Estimation of the rate of energy production of rat mast cells in vitro.

Rat mast cells were treated with glycolytic and respiratory inhibitors. The rate of adenosine triphosphate depletion of cells incubated with both types of inhibitors and the rate of lactate produced in presence of antimycin A and glucose were used to estimate the rate of oxidative and glycolytic ATP synthesis.

Adenosine Triphosphate↗
PubMed1981

Dependence of anaphylactic histamine release from rat mast cells on cellular energy metabolism.

The relation between anaphylactic histamine release and the adenosine triphosphate (ATP) content of the mast cells was studied. The cells were incubated with glycolytic (2-deoxyglucose) and respiratory inhibitors (antimycin A and oligomycin) in order to decrease the ATP content of the cells prior to initiation of the release process by the antigen-antibody reaction. The secretory capacity of mast cells was less related to the cellular level of ATP at the time of activation of the release process by the antigen-antibody reaction than to the rate of cellular energy supply. Furthermore, mast cells were pretreated with 2-deoxyglucose. The release of histamine from these cells was reduced when respiratory inhibitors were added to the cell suspension 5 to 20 sec after exposure of the cells to antigen. This may indicate that the secretory process requires energy, and it seems necessary that energy should be produced as the release of histamine takes place.

Adenosine Triphosphate↗
PubMed1981

Rifampin chemoprophylaxis for household contacts of patients with invasive infections due to Haemophilus influenzae type b.

To determine the efficacy of rifampin chemoprophylaxis in eradication of oropharyngeal carriage of Haemophilus influenzae type b, we conducted a multicenter, double-blind, placebo-controlled trial among household contacts of patients hospitalized for invasive HIB infection. Seventy-nine index patients and 400 close contacts were studied; 26.5% of contacts were colonized. The efficacy of rifampin (10 mg/kg/dose, 600 mg/dose maximum, twice daily for two days) in eradicating carriage was 52% and varied with age (75.6% in persons greater than or equal to 5 and 27% in those less than 5 years). Eradication rates in those less than 5 years were not significantly better than for placebo. No resistant isolates were encountered in sensitivity testing. The low efficacy of this rifampin regimen in young children precludes its routine use as a chemoprophylactic agent for family contacts. The occurrence of three cases of invasive HIB infection in individuals outside the defined contact group raises concern regarding the efficacy of any chemoprophylactic regimen.

Clinical Trials as Topic↗
PubMed1980

Histamine release induced from rat mast cells by the ionophore A23187 in the absence of extracellular calcium.

Isolated rat mast cells were used to study whether ionophore A23187 could induce histamine release by mobilizing cellular calcium. The histamine release was a slow process which was completed after about 20 min incubation with A23187. The A23187-induced histamine release was inhibited after incubation of the cells with EDTA for 1 h in a 37 degrees C water bath in calcium-free medium. Reintroduction of calcium in excess of EDTA induced the release of histamine. The observations suggest that A23187 can induce histamine release by mobilizing a cellular pool of calcium.

Animals↗
PubMed1980

Further observations on the utilization of adenosine triphosphate in rat mast cells during histamine release induced by the ionophore A23187.

1 The relation between A23187-induced histamine release and the energy metabolism of the rat mast cells has been studied. 2 Ethacrynic acid was used as an inhibitor of calcium-induced histamine release from mast cells primed with the ionophore A23187, and to study calcium-induced changes in the adenosine triphosphate (ATP) content and the rate of lactate production of A23187-primed mast cells. 3 Ethacrynic acid by itself decreased the rate of glycolytic ATP production. 4 By measurement of the ATP content and the lactate production of mast cells with or without secretory activity, the increased demand of energy for exocytosis was estimated to be equivalent to 0.14 pmol of ATP pr 10(3) mast cells.

Adenosine Triphosphate↗
PubMed1979

Adenosine triphosphate levels during anaphylactic histamine release in rat mast cells in vitro. Effects of glycolytic and respiratory inhibitors.

The adenosine triphosphate (ATP) content of rat mast cells was studied during and after anaphylactic histamine release. The almost identical time course of ATP decrease from mast cells treated with either glycolytic or respiratory inhibitors supports the view that the ATP depletion was largely related to the histamine release process and not to an uncoupling of oxidative phosphorylation by an increased concentration of cytosol Ca2+. The ATP content of the cells was not restored within the 2 h of observation. No inhibition of lactate production from mast cells exposed to antigen in the presence of respiratory inhibitors and glucose was observed. Based on the lactate production from mast cells, the turnover time of ATP was calculated to be about 3/4 min.

Adenosine Triphosphate↗
PubMed1979

Utilization of adenosine triphosphate in rat mast cells during histamine release induced by the ionophore A23187.

The role of endogenous adenosine triphosphate (ATP) in histamine release from rat mast cells induced by the ionophore A23187 in vitro has been studied. 2 The amount of histamine released by calcium from rat mast cells primed with the ionophore A23187 was dependent on the ATP content of the mast cells. 3 In aerobic experiments a drastic reduction in mast cell ATP content was found during the time when histamine release induced by A23187 takes place. 4 Anaerobic experiments were performed with metabolic inhibitors (antimycin A, oligomycin, and carbonyl cyanide p-trifluorometroxyphenylnydrazone), which are known to block the energy-dependent calcium uptake by isolated mitochondria. The mast cell ATP content was reduced during A23187-induced histamine release under anaerobic conditions in the presence of glucose. This indicates an increased utilization of ATP during the release process. 5 The observations are consistent with the view that energy requiring processes are involved in ionophore-induced histamine release from rat mast cells although part of the ATP reduction in the aerobic experiments may be due to an uncoupling effect of calcium on the oxidative phosphorylation.

Adenosine Triphosphate↗
PubMed1978

Mechanism of histamine release from rat mast cells induced by the ionophore A23187: effects of calcium and temperature.

1 The mechanism of histamine release from a pure population of rat mast cells induced by the lipid soluble antibiotic, A23187, has been studied and compared with data for anaphylactic histamine release reported in the literature. 2 Histamine release induced by A23187 in the presence of calcium 10(-3) mol/l was completed in 10 minutes. By preincubation of the mast cells with A23187 for 10 min in the absence of calcium the histamine release induced by calcium, 10(-3) mol/l or 5 x 10(-3) mol/l, was completed in 90 s and 45 s, respectively. 3 A23187-induced histamine release was maximal with calcium 10(-3) mol/l when the cells were incubated at 33 to 39 degrees C for 10 minutes. 4 The cellular mechanism, which was stimulated by A23187 and calcium for the release of histamine, was irreversibly inactivated by incubation at 45 degrees C. 5 An inhibition of energy metabolism was excluded as the cause of the heat inactivation. 6 The dependence of A23187-induced histamine release on calcium and temperature, the time course of histamine release and the heat inactivation are consistent with the view that the same mechanism is involved in A23187-induced and anaphylactic histamine release.

Adenosine Triphosphate↗
PubMed1978

Hemipelvectomy. Postoperative rehabilitation assessed on the basis of 41 cases.

Rehabilitation was evaluated on the basis of 41 consecutive hemipelvectomies for malignant tumours. Owing to early metastasization and death, 11 patients were not supplied with prostheses, while prosthetic fitting was attempted in the remaining 30. Of this number 27 completed prosthetic training, with the result that 15 used their prosthesis, while 12 discarded it after some time, six because of poor general health owing to recurrence of the tumours and six because they felt that the prosthesis was too heavy and difficult to wear. Twenty-three returned to work. After elimination of the most severely tumour-affected patients, there were 19 one-year survivors without recurrence. Thirteen of them were using their prosthesis every day, and thirteen had gone back to work. Serious mental sequelae were found in five patients, including four with long-lasting exogenous depressions and one with anxiety neurosis.

Adult↗