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B Ek

Publications and source records attributed to B Ek.

At least 73 records · Page 4Linked to original sources
PubMed1987

Regulation of c-myc transcription and protein expression during activation of normal human B cells.

The close link between an actively expressed c-myc gene locus and cellular proliferation has been established in a variety of cell types. By using normal human peripheral blood B cells as a model for in vivo quiescence, we have assessed the expression pattern of the c-myc gene in terms of transcriptional activation and concurrent production of c-myc protein, following induction by antibodies directed against antigens on the cell membrane. Both the 1F5 monoclonal antibody, which reacts with the pan B cell antigen CD20, and the anti-mu could promote transcriptional activation of the c-myc gene roughly corresponding to the increased levels of cytoplasmic c-myc mRNAs. In addition, more than 80% of the B cells could be induced to express c-myc protein by either stimulus. Since treatment only with polyclonal anti-mu renders the B cells competent to proliferate in the presence of BCGF, c-myc protein expression is not per se sufficient for cell cycle progression into S phase.

B-Lymphocytes↗
PubMed1987

Coping and social activity patterns among relatives of cancer patients.

In this study we have examined how relatives of cancer patients change their social patterns when they are offered increased possibilities to take active part in the care of the patient. Relatives who were offered such an activation programme were compared with relatives who were offered the usual routine programme ('comparison group'). The instrument used for the present study was a modified version of the 'coping wheel' introduced by Shalit. Fifty relatives in the activation group and 45 in the comparison group were followed at repeated occasions approximately once a month during the patient's treatment. Twenty-two in the activation group and 19 in the comparison group were followed 1 and 2 month(s) after the patient's death. Relatives in the activation group reported a significantly higher proportion of activities concerning friends and relatives (P less than 0.04) during the treatment period. At the last observation occasion preceding death, relatives in the comparison group reported significantly more areas dealing with 'own feelings' (P less than 0.04). Relatives in the activation group reported a significantly greater increase in number of 'own activities' from the last observation preceding the patient's death to 1 month after death (P less than 0.04) compared to the comparison group.

Adaptation, Psychological↗
PubMed1987

Autoradiographic location of beta-adrenoceptor subtypes in cat colon smooth muscle.

In order to localize beta-adrenoceptors 125I-(-)pindolol (IPIN) was used in binding to sections from cat colon. The binding characteristics for IPIN to beta-adrenoceptors on colon sections were estimated by demonstrating reversible binding in the presence of isoprenaline and by steroselective binding to the isomers of propranolol. The binding of IPIN to both beta 1- and beta 2-adrenoceptors was shown by biphasic displacement curves in the presence of the selective beta-adrenoceptor compounds betaxolol, ICI 118.551 and procaterol. The colon sections were found to contain proportions of beta 1-adrenoceptors (30-50%) and beta 2-adrenoceptors (50-70%). In the autoradiographic studies, 100% of the developed grains after exposure of IPIN to the photographic emulsion were displaced by 50 microM of isoprenaline. By microscopic counting at autoradiographic grains, 30-40% of the grains were found in the circular smooth muscle, while 60-70% of the grains were found in the longitudinal smooth muscle. A concentration of 2 nM ICI 118.551 completely displaced all grains in the circular smooth muscle and partly displaced those found in the longitudinal smooth muscle. A high concentration of ICI 118.551 (1 microM) displaced all grains above background from the smooth muscle. It is concluded that the circular smooth muscle only contains beta 2-adrenoceptors, while longitudinal smooth muscle may contain a proportion of beta 1-adrenoceptors. Whether such a location of beta adrenoceptors can be related to the beta 1-adrenoceptor-mediated inhibition of colon motility can not be clarified from these studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Agonists↗
PubMed1987

The quantity of protein-bound [32P]phosphotyrosine in hepatocytes and fibroblasts. The effects of tyrosine protein kinase activating agents.

Tyrosine protein kinase activities have been demonstrated in transformed and normal cell systems. So far, few data on the quantity of protein-bound phosphotyrosine in intact cells have been published. A knowledge of the stoichiometric increase in phosphotyrosine in cells after hormonal induction could be of interest when evaluating the importance of the tyrosine protein kinase activities found. By the addition of a known amount of unlabeled phosphotyrosine to the precipitated protein of 32P-phosphate-labeled cells it was possible after alkaline hydrolysis to spectrophotometrically follow the phosphotyrosine during consecutive chromatographies of the material. From the specific radioactivity of the purified phosphotyrosine the initial concentration of [32P]phosphotyrosine could be calculated. The method proved to be useful for the determination of [32P]phosphotyrosine is small amounts of cells. The minimum detectable amount of [32P]phosphotyrosine was about 1 pmol, and as an example, only 2.5 X 10(6) fibroblasts were needed. By this method it was shown that platelet-derived growth factor increased protein-bound [32P]phosphotyrosine from 600 to 3,200 pmol/g of fibroblasts, while insulin only increased the [32P]phosphotyrosine from 110 to 120 pmol/g of hepatocytes.

Cells, Cultured↗
PubMed1986

Specific cleavage of the fibroblast receptor for platelet-derived growth factor by an endogenous Ca2+-dependent thiol protease.

Previous studies have shown that platelet-derived growth factor (PDGF) stimulates the phosphorylation of two components in membranes prepared from human fibroblasts in the presence of Ca2+. One of these represents the 185-kDa PDGF receptor, which undergoes autophosphorylation, and the other has an Mr of 130 000. We show in this communication that the 130-kDa component is derived from the 185-kDa receptor via proteolysis by an endogenous Ca2+-dependent protease, which is dependent on a reduced -SH group for its activity. The 130-kDa fragment contains several of the characteristics of the receptor, such as the PDGF-binding site and the major autophosphorylation sites. Furthermore, the cleaved receptor retains tyrosine kinase activity.

Calcium↗
PubMed1986

Increased beta I-adrenoceptor density after 6-hydroxydopamine pretreatment in rat colon and lung.

Estimation of beta-adrenoceptor-binding sites with 125I-(-)-pindolol in rat colon show a proportion of 30% beta I-adrenoceptors and 70% beta 2-adrenoceptors. Studies on the isolated colon strip have revealed a neuronal beta-adrenoceptor involved in the inhibitory response of colon motility to beta-adrenoceptor stimulation. In order to further characterize the beta-adrenoceptors in the colon, acute and chronic treatments with 6-hydroxydopamine were made. Both acute pretreatment of rats with 6-hydroxydopamine for 8 and 24 h (one intravenous injection) and chronic treatment for 3 days (implanted osmotic mini-pumps), reduced the noradrenaline tissue content by 90%, and successively increased the beta-adrenoceptor-binding sites from 14.2 to 21.7 fmol mg-I P-I in colon and from 158 to 240 fmol mg-I P-I in lung membranes. Displacement of the radiolabelled ligand by the selective beta-adrenoceptor antagonists, pafenolol and ICI 118.551 showed that the density of beta I-adrenoceptor binding sites was more than doubled, whereas the density of beta 2-adrenoceptor-binding sites was only marginally increased by chronic treatment with 6-hydroxydopamine. Thus sympathetic denervation by 6-hydroxydopamine treatment produced a selective increase in beta I-adrenoceptors in the rat colon. These results may indicate that stimulation of beta I-adrenoceptors in both colon and lung have a neuronal linkage.

Animals↗
PubMed1985

Plasma and skeletal muscle electrolytes in patients with Crohn's disease.

Plasma and skeletal muscle electrolytes were measured in 13 patients with Crohn's disease, and in an age- and sex-matched reference group. Patients with Crohn's disease demonstrated significantly lower muscle potassium content (p less than 0.01) than did controls. Patients with extensive involvement of the bowel tended to have lower muscle potassium content. The patient population did not differ significantly from the controls with regard to skeletal muscle magnesium content but displayed a far wider range of values. Our results indicate that potassium depletion is present in nonresected patients with Crohn's disease.

Adult↗
PubMed1985

Aggravation of thiamine deficiency by magnesium depletion. A case report.

A patient with Crohn's disease and long-standing diarrhea resulting in a combined thiamine and magnesium deficiency is presented. Despite massive doses of thiamine i.v., the symptoms of thiamine deficiency could not be suppressed until the magnesium deficiency was corrected as well. This case report emphasizes the dependence of thiamine on magnesium for an adequate function in the body.

Adult↗
PubMed1985

Platelet-derived growth factor: mechanism of action and relation to oncogenes.

Recent studies of platelet-derived growth factor (PDGF) have revealed several structural and functional similarities between this growth factor or components linked to its mechanism of action and certain oncogene products: PDGF itself has a structural homology with the transforming protein of simian sarcoma virus, the PDGF receptor has a functional homology (tyrosine kinase activity) with a family of oncogene products, and PDGF induces the expression of the cellular counterparts of myc and fos. In addition, several tumour cell lines have been found to produce PDGF-like growth factors, which may cause autocrine stimulation of growth. We interpret these findings as indicating that regulatory components along the PDGF-dependent mitogenic pathway may have oncogenic properties if they are inappropriately expressed or activated.

Cell Line↗
PubMed1985

Effect of felodipine on renal hemodynamics and excretion in the dog.

The effects of felodipine on renal hemodynamics and excretion were evaluated in the anesthetized dog. Unilateral renal arterial infusion of felodipine produced ipsilateral increases in the absolute and fractional excretion of sodium and water which were greater than those of potassium; these effects occurred in the absence of changes in mean arterial pressure, renal blood flow, or glomerular filtration rate. There were no significant effects on renal hemodynamic or excretory function in the contralateral kidney. The unilateral renal arterial infusion of isotonic saline or vehicle produced no significant effects on renal hemodynamic or excretory function in either ipsilateral or contralateral kidney. Felodipine, a calcium antagonist with vasodilator antihypertensive properties, in doses which do not affect systemic or renal hemodynamics in the dog, increased urinary flow rate and sodium excretion by decreasing renal tubular water and sodium reabsorption. As a vasodilator antihypertensive agent, felodipine possesses potentially advantageous diuretic and natriuretic properties.

Animals↗
PubMed1985

Studies on mechanisms for beta-adrenoceptor mediated inhibition of colon motility.

Radioligand binding studies show that both beta 1- and beta 2-adrenoceptors were present in the colon wall, but with a considerably higher concentration of the beta 2-subtype than of the beta 1-subtype. The effect of selective beta-adrenoceptor agonists on isometric force recordings of spontaneous contractile activity and electrically integrated activity were determined in isolated proximal cat and rat colon strips. The use of selective beta-adrenoceptor blocking agents revealed both beta 1- and beta 2-adrenoceptor inhibitory interaction by the beta-agonists employed. Comparison of qualitative effects of the selective beta-adrenoceptor agonists led to the hypothesis that the beta 1- and beta 2-adrenoceptors were separated on two functional levels within the colon organ. This hypothesis was confirmed by the reduced maximal inhibitory response of the partial beta-adrenoceptor agonist, prenalterol, induced by tetrodotoxin. Further confirmation was found in the decrease in affinity after tetrodotoxin treatment of the beta-adrenoceptor antagonist, metoprolol. Pretreatment with 6-hydroxy-dopamine induced an upregulation of the beta 1-adrenoceptor density but a decrease in the total efficacy of prenalterol. This may additionally indicate a beta 1-adrenoceptor-mediated effect of endogenously released noradrenaline and the requirement of sympathetic nerves for part of the beta-adrenoceptor mediated effect. Atropine and physostigmine influenced the basal contractile activity in a way suggesting that endogenous cholinergic tone existed in the isolated colon preparation. Furthermore, atropine shifted the concentration-effect curves for isoprenaline and terbutaline in a way suggesting that this tonus exerts functional antagonism for the beta-adrenoceptor stimulation. The efficacy of prenalterol was increased by atropine and was markedly reduced by extremely low concentrations of carbachol and bethanechol. This reveals that functional antagonism may be exerted at more than one effector level in the colon wall. Furthermore, it indicates that the nerves responsible for the propagation of the inhibitory effect to beta-adrenoceptor stimulation in the nervous plexa are not of the cholinergic type. It is concluded that the beta 1-adrenoceptor mediates the inhibitory sympathetic effect mainly in nervous plexa of the colon, whereas the beta 2-adrenoceptor mediates this effect at the smooth muscle cells.

Adrenergic beta-Agonists↗
PubMed1984

Use of an antiserum against phosphotyrosine for the identification of phosphorylated components in human fibroblasts stimulated by platelet-derived growth factor.

In search for possible intracellular mediators of the mitogenic signal induced by platelet-derived growth factor (PDGF), we have investigated tyrosine-specific phosphorylation stimulated by PDGF in intact human fibroblasts. Cells were metabolically labeled, either with [32P] orthophosphoric acid or with [35S]methionine, and thereafter treated with PDGF for various times. Lysates from the cell cultures were then immunoprecipitated with an antiserum specifically recognizing phosphotyrosine. Analysis of the precipitated radioactivity by sodium dodecyl sulfate-gel electrophoresis and autoradiography or fluorography showed the appearance of a 185-kDa protein in cells stimulated with PDGF; maximum yield was at about 5 min after the addition of PDGF. This component was found to have several characteristics in common with the PDGF receptor, including similar Mr, binding to immobilized wheat germ agglutinin, and incorporation of phosphate on tyrosine residues after exposure to PDGF. We conclude that the 185-kDa component probably represents the PDGF receptor proper. Phosphoamino acid analysis of the 185-kDa protein/PDGF receptor, precipitated with the antiphosphotyrosine immune serum, revealed that it, in addition to phosphotyrosine, also contained phosphoserine. PDGF also consistently stimulated the phosphorylation of components of Mr values of 300,000 to 200,000, 115,000, 72,000, 54,000, 45,000, and 35,000. Some of these components may be involved in the intracellular transmission of the PDGF-induced mitogenic signal.

Antigen-Antibody Complex↗
PubMed1984

Coexpression of a PDGF-like growth factor and PDGF receptors in a human osteosarcoma cell line: implications for autocrine receptor activation.

The expression of both a PDGF-like growth factor and functional PDGF receptors within a clonal human osteosarcoma cell line (U-2 OS Cl 6) is demonstrated. These molecules are able to interact and induce tyrosine-specific phosphorylation and early actin reorganization in the osteosarcoma cells, effects similar to those that PDGF induces in normal responsive cells. Furthermore, immunoprecipitation with an antiserum against phosphotyrosine revealed that a 115 kd protein was constitutively phosphorylated in U-2 OS Cl 6 cells. A phosphorylated protein of similar apparent molecular weight has been found in human fibroblasts, but only after stimulation with PDGF. These data indicate that the PDGF-receptor-dependent pathway is constitutively activated in this cell line. Extracellularly added PDGF antibodies did not, however, affect the transformed properties or growth rate of U-2 OS Cl 6 cells in vitro. This indicates that autocrine PDGF receptor activation may be insignificant for maintaining the transformed state of this tumor cell line, or that autocrine receptor activation occurs in a compartment where it is inaccessible to extracellularly added antibodies.

Antibodies↗
PubMed1984

Effect of long-term penicillamine therapy on erythrocyte CuZn superoxide dismutase activity.

The effect of long-term penicillamine therapy on erythrocyte CuZn superoxide dismutase activity was investigated. For comparison the serum ceruloplasmin and serum copper contents were also analysed. Seven of the 11 penicillamine-treated patients had CuZn superoxide dismutase activities below the reference interval of the parameter. Levels down to about 50% of the mean of controls were observed in several cases. In five and in four of the 11 patients respectively decreases in serum ceruloplasmin and serum copper were found. Whereas among the penicillamine-treated patients there was a good correlation between serum ceruloplasmin and serum copper, the correlation between these parameters and erythrocyte CuZn superoxide dismutase was only fair. Erythrocyte CuZn superoxide dismutase is probably a suitable parameter for monitoring intracellular copper availability during penicillamine therapy.

Adult↗
PubMed1983

Synthesis of a PDGF-like growth factor in human glioma and sarcoma cells suggests the expression of the cellular homologue to the transforming protein of simian sarcoma virus.

Several human normal and neoplastic cell lines were screened for production of PDGF receptor competing activity. Conditioned medium from two sarcomas and one glioma blocked 125I-PDGF binding to human foreskin fibroblasts in a dose-dependent manner. In each case this effect was abolished when the conditioned medium was pretreated with PDGF-antiserum, indicating that the receptor competing activity was immunologically related to PDGF. Direct evidence for de novo synthesis of a PDGF-like component in the cultures was afforded by 35S-cysteine labeling of the three cell lines, followed by immunoprecipitation with PDGF antiserum. This resulted in the specific precipitation of a 31,000 molecular weight labeled protein, which upon reduction was split into two polypeptides of molecular weights 17,000 and 16,500. The significance of these findings in view of the recently discovered structure homology between PDGF and the transforming gene product of simian sarcoma virus, p28sis, is discussed.

Binding, Competitive↗