Search PubMed⌕ Search

Biomedical subjects

J Jensen

Publications and source records attributed to J Jensen.

At least 541 records · Page 30Linked to original sources
PubMed1983

ATP binding to solubilized (Na+ + K+)-ATPase. The abolition of subunit-subunit interaction and the maximum weight of the nucleotide-binding unit.

Membrane-bound (Na+ + K+)-ATPase from pig kidney outer medulla shows apparent heterogeneity in its ATP-binding site population when assays are carried out in the presence of K+. This finding has been interpreted as being due to interaction between (at least) two subunits, each containing an ATP-binding site. Treating the membrane-bound enzyme with the detergent, C12E8, has been shown to solubilize enzymatically active alpha beta-protomers. We show that in the dissolved enzyme all ATP-binding sites in the population are identical both in the absence and in the presence of K+, which would be consistent with an abolition of identical both in the absence and in the presence of K+, which would be consistent with an abolition of subunit-subunit interaction. This supports previous suggestions that enzyme solubilized by C12E8 is monomeric and that the membrane-bound enzyme is not. Differential extraction of enzyme-containing membranes with C12E8 yielded preparations with an ATP-binding capacity of up to 5.8 nmol per mg protein, measured by the method of Lowry et al. (Lowry, O.H., Rosebrough, N.J., Farr, A.L. and Randall, R.J. (1951) J. Biol. Chem. 193, 265-275), with bovine serum albumin as standard. Evidence is presented that makes it likely that preparations with an ATP-binding capacity of 7.5 nmol per mg protein (as determined by the above-mentioned assay) will be obtainable. This corresponds to an alpha beta-protomer molecular weight of 133 000 which approximates closely to the minimum value found in the literature for an alpha beta-protomer (i.e., 126 000).

Adenosine Triphosphate↗
PubMed1983

The K+-induced apparent heterogeneity of high-affinity nucleotide-binding sites in (Na+ + K+)-ATPase can only be due to the oligomeric structure of the enzyme.

K+ induces an apparent heterogeneity among an otherwise homogeneous population of nucleotide-binding sites in (Na+ + K+)-ATPase preparations from pig kidney. With the help of ouabain we show that this heterogeneity cannot be due to a mixture of different and independent sites and conclude that each enzyme molecule must contain two nucleotide site-containing units that show interaction. Na+ induces an apparent heterogeneity among an otherwise homogeneous population of ouabain-binding sites. The argument is, therefore, extended to include one ouabain site on each of the structural units that bind nucleotide. All these structural units are shown to hydrolyse substrate at identical rates. Using the presently available molecular weight data, it is concluded that the enzyme is composed of two subunits each possessing one nucleotide-binding site, one ouabain-binding site, one alpha-peptide and the capacity for hydrolysing ATP and p-nitrophenyl phosphate.

Adenosine Diphosphate↗
PubMed1983

Age and immune response to a surgical stress.

We studied the effects of age and a relatively standardized stress (elective inguinal herniorrhaphy) on immune response. The patients included 20 men, ten at least 60 years old and ten younger, who were free of infection and illness and had not had prior surgery. Immune responses were measured one day before and five and 30 days after operation. We determined immunoglobulin levels, performed three delayed-hypersensitivity skin tests and a test for neutrophil chemotaxis, and measured lymphocyte responses to autologous cells, phytohemagglutinin-P (PHA), concanavalin A (Con A), and pokeweed. We also studied responses in 40 controls matched for age and sex. The responses to PHA and Con A were significantly lower in older patients than in controls at five days after operation; responses to Con A were still significantly lower at 30 days. Morbidity correlated with depressed immune responses in both age groups, even when there was no difference between older and younger patients.

Age Factors↗
PubMed1983

An in vitro study of the comparative effectiveness of obturating curved root canals with gutta-percha cones, silver cones, and stainless steel files.

The quality of apical seal obtained with gutta-percha cones, silver cones, and stainless steel files was assessed in 120 freshly extracted teeth with moderately or severely curved root canals. Teeth were coated with wax, except in the apical foramen area, and immersed in 2 percent methylene blue solution for 48 hours. Apical leakage was quantitated by a linear measurement of the distance that the dye penetrated along the root canal and by a volumetric measurement of the quantity of dye within the root. There was a highly significant (p less than 0.001) correlation between the two measurements. Root canals filled with silver cones showed significantly less apical leakage than those filled with gutta-percha or stainless steel files, regardless of degree of curvature. For both silver cones and stainless steel files, leakage was less in severely curved roots than in moderately curved roots.

Dental Bonding↗
PubMed1983

Stress and immune function in diabetes mellitus.

Type I diabetic men were found to have a greater number of stresses, more perceived stress per episode, greater anxiety, poorer immune function, and less metabolic control than Type II diabetic men. Degree of family support and compliance with the medical regimen did not differ. Correlation of perceived stress with immune function and metabolic control showed that Type I had more correlates than Type II, with more perceived stress associated with more depressed immune responses.

Adult↗
PubMed1983

Dose-response and withdrawal effects on climacteric symptoms after hormonal replacement therapy. A placebo-controlled therapeutic trial.

Out of a sample of 162 early post-menopausal women, aged 45-54 yr, 131 completed a placebo-controlled study to investigate the effect of sex hormones on mild climacteric symptoms with special reference to the dose-response relationship and withdrawal effects. The women were followed up for 42 mth under four different study programmes. All the women were examined every 3 mth and a blind assessment made of the menopausal index estimated according to Kupperman et al. The data revealed a highly significant reduction in climacteric symptoms in the hormone-treated women as compared with the placebo group (P less than 0.001), a highly significant dose relationship between climacteric symptoms and treatment with 4, 2 and 1 mg oestradiol, respectively (P less than 0.001), a highly significant and dose-dependent rebound phenomenon after withdrawal of hormone treatment (P less than 0.001)--which levelled off after 6 mth following withdrawal--and complete relief of hot flushes with the two highest doses of oestradiol (4 and 2 mg oestradiol). It is concluded that sex hormones have a beneficial effect in post-menopausal women with even mild symptoms.

Climacteric↗
PubMed1983

Surgical stress in the healthy elderly.

Surgery has sometimes been studied as a stressful event. The aim here was to determine the relationship between degrees of anxiety before surgery and postoperative outcomes in healthy old and young men. Old and young men were selected if they had no illnesses or prior surgery and were scheduled for elective hernia repair. Levels of anxiety were measured preoperatively along with other physiologic, psychologic, and immunologic modalities. Operative data and follow-up data for 30 days were obtained. Old and young men did not differ significantly before surgery. When age groups were divided by preoperative anxiety and their postoperative outcomes compared, more anxiety was associated with more pain-relieving medications and more disability days in each age group. Furthermore, the old anxious had even more disability days and complications than did other groups. The study points to the need to prepare the old, even those essentially in very good health, for even a minor surgical stress in order to improve their overall health outcomes.

Adult↗
PubMed1983

Immune-mediated thrombocytopenia of malaria.

Thrombocytopenia frequently complicates malarial infections but the mechanism has not been elucidated. We studied 28 patients with malarial infections and noted that 16 of 17 thrombocytopenic patients had elevated levels of platelet-associated IgG (PAIgG). In all thrombocytopenic patients studied, the level of PAIgG returned to normal as the platelet count rose to normal levels. To study the mechanism of the elevated platelet-bound IgG, IgG and F(ab')2 from patients with recurrent Plasmodium falciparum infections was purified and radiolabeled. Labeled and unlabeled P. falciparum antigen was also prepared. IgG did not nonspecifically bind to malaria-damaged platelets. Binding studies with 3H-malarial antigen demonstrated platelets have saturable binding sites for malarial antigen. Increasing concentrations of malarial antigen displaced the 125I-IgG antimalarial antibody from the platelets. The binding of 125I-IgG and 125I-F(ab')2 was similar and this excluded significant immune complex binding. The thrombocytopenia that complicates at least some malarial infections is caused by immune mechanisms; specific IgG binds to platelet-bound malaria antigen through the Fab portion of the immunoglobulin molecule.

Binding Sites, Antibody↗
PubMed1983

Parturition and pelvic fracture. Follow-up of 34 obstetric patients with a history of pelvic fracture.

Thirty-four women with a history of pelvic fracture gave birth. Ten had experienced increasing or recurrent pain during the course of their pregnancy. Twenty-seven women gave birth without complications, including 13 patients with displaced pelvis. In only one patient was cesarean section carried out on suspicion of disproportion. Cesarean section was carried out in another case because of resymphysiolysis and in one because of other complications to the pregnancy. Two underwent vacuum extraction because of secondary inertia, but subsequently they gave birth by the vaginal route without complications. In connection with pregnancy and birth, 2 patients had resymphysiolysis. They were the only patients of 8 with symphysiolysis who had undergone osteosynthesis, and both had had the material removed before pregnancy. It is concluded that separation of the symphysis in a pelvic fracture is a more serious complication in subsequent parturition than is displacement of the bony birth canal.

Adult↗
PubMed1983

Efficacy of trimipramine and cimetidine in the treatment of duodenal ulcer. A double-blind comparison.

One hundred and fourteen consecutive outpatients with endoscopically proven duodenal ulcers were allocated in a double-blind study to treatment with either trimipramine (Surmontil), 50 mg at bedtime, or cimetidine (Tagamet), 200 + 200 + 200 + 400 mg/day, using identical-appearing active and placebo tablets to fill in the treatment scheme. One hundred and eight patients completed the study. Ulcer healing was assessed by endoscopy at 3, 6, and 9 weeks. Clinical symptoms and antacid consumption were recorded by means of interviews and a diary card system. The cumulated healing rate with cimetidine and trimipramine, respectively, was at 3 weeks 64% versus 40% (p less than 0.05), at 6 weeks 89% versus 65% (p less than 0.05), and 9 weeks 91% versus 78% (n.s.). We found no significant differences between the two groups with regard to pain relief, antacid consumption, or general symptomatic improvement.

Adolescent↗