Biomedical subjects

B O Jensen

Publications and source records attributed to B O Jensen.

5 recordsLinked to original sources

PubMed1999

Role of autocrine stimulation on the effects of cyclic AMP on protein and lipid phosphorylation in collagen-activated and thrombin-activated platelets.

We compared several responses in thrombin-stimulated and collagen (type I)-stimulated platelets with and without forskolin and inhibitors of autocrine stimulation (IAS: an ADP-removing system of creatine phosphate/creatine phosphokinase, Arg-Gly-Asp-Ser peptide to prevent fibrinogen/fibronectin binding to GPIIb/IIIa, SQ 29.548 as a thromboxane A2 receptor antagonist, cyproheptadine as a serotonin receptor antagonist, BN 52021 as a platelet-activating factor receptor antagonist). The pattern of tyrosine-phosphorylated proteins, the phosphorylation of lipids in the polyphosphoinositide cycle and phosphorylation of pleckstrin (P47) were studied as markers for signal-transducing responses, exposure of CD62 (P-selectin) and CD63 (Glycoprotein 53), as well as secretion of ADP + ATP and beta-N-acetyl-glycosaminidase were studied as final activation responses. Clear differences between thrombin-stimulated and collagen-stimulated platelets were observed. First, practically all protein-tyrosine phosphorylation induced by thrombin was inhibited by IAS, while a partial inhibition was observed for collagen; the phosphorylation due to collagen alone was apparently stimulated by elevation of cAMP. Secondly, the other responses to thrombin were inhibited by increased levels of cAMP, independent of autocrine stimulation. In contrast, only the autocrine part of the collagen-induced responses was inhibited by elevation of cAMP. Thus, the inhibition by elevated cAMP seen in collagen-stimulated platelets seems to be due to removal of the G-protein-mediated activation from secreted autocrine stimulators either by IAS or forskolin. The remaining activity is a pure collagen effect which is not affected by elevated levels of cAMP.

Antigens, CD↗

PubMed1997

A polarographic method for measuring dissolved nitric oxide.

A polarographic method for measuring the concentration of authentic nitric oxide (NO) in aqueous solutions is described. When solutions of NO were injected into aqueous solutions containing dissolved oxygen, NO reacted with oxygen to give nitrite. The amount of nitrite formed in this reaction (analyzed by capillary electrophoresis) was compared with the amount of oxygen consumed (measured by polarography). We observed a linear relationship between the amount of consumed oxygen and the amount of nitrite formed in the measured range (20-100 nmol NO-2) (R2 = 0.89). These results demonstrate that polarographic measurements of the amount of oxygen consumed in the reaction with NO could be used to estimate the concentration of dissolved NO in authentic NO solutions. There are several advantages to measuring consumed oxygen by polarographic methods: The method is simple and can be performed immediately prior to utilization of the NO solutions, it does not require any NO calibration standards and it fully discriminates between NO and oxidation products of NO. An additional advantage is, therefore, that stock solutions of NO can be stored for an indefinite period of time prior to measurement. Both the preparation of authentic NO solutions and the measurement of their NO content are therefore simplified. We also demonstrate that a slow infusion of authentic NO solution to cell suspensions in vitro makes it possible to study the rapid, reversible biological effects of NO.

Humans↗

PubMed1993

[Spinal analgesia for cesarean section].

Over a twelve-month period, 47 of a total of 127 women had spinal anaesthesia (SA) for caesarean section (SC). Data from the anaesthesia and the postoperative period were collected and a questionnaire was sent to the mothers after discharge. The analgesia was sufficient in 45 patients. Two had general anaesthesia (GA). One further patient had GA because of overwhelming anxiety. Despite crystalloid preloading, 45% had a significant decrease in systolic blood pressure. Hypotensive cases were treated with a bolus of ephedrine i.v. Forty-one of the new-born babies scored Apgar 10/1 and all scored 10/5. No postdural puncture headaches were observed during the patients' stay in hospital. Forty women answered the questionnaire, and of these, 38 said they would prefer SA in the event of future SC. Six out of eight women who had previously had epidural analgesia preferred SA. We find that SA is a safe, easy, and reliable method for SC, although supplementary analgetic and antiemetic may be needed, but it is mandatory to maintain the systolic blood pressure (cardiac output) close to the preanalgetic values.

Adult↗

PubMed1992

[From endothelium-derived relaxing factor to L-arginine and nitrogen monoxide].

Endothelium-derived relaxing factor has been identified as nitric oxide. It was originally found to be released from endothelial cells, mediating vascular relaxation and platelet inhibitory action. Nitric oxide is formed enzymatically from L-arginine by nitric oxide synthase, and this enzyme has up to the present been demonstrated in endothelial cells, platelets, neutrophils, macrophages, neurons and smooth muscle cells. Both a constitutive and an inducible nitric oxide synthase have been identified, which may serve different physiological/pathophysiological purposes. The biological implications of nitric oxide have now been manifested, and the number of reports on its physiological role is rapidly increasing. Compounds which inhibit the formation of nitric oxide have become available, and this expanding field has created great interest amongst clinicians.

Amino Acid Oxidoreductases↗

PubMed1991

[Working and living conditions of Danish medical assistant].

In spring 1988 almost 6,000 members of the Danish Association of Young Doctors answered a questionnaire containing 132 questions about their working and living conditions. The Danish study shows that many young doctors are worried by uncertain conditions of employment, lack of opportunities for further training, and demanding emergency duty. Traditional sex role patterns in the families afflict the women doctors who have difficulty in holding their own in the keen competition. Stress in different forms is regarded as a problem by about 25 per cent. Almost half of the respondents had wholly or partially regretted their choice of a career and one fifth had considered changing their profession. The physicians own occupational injuries are substantially (24 per cent) underreported. Swedish and Finnish studies indicate that the problems in the medical profession are similar in the Nordic countries.

Alcohol Drinking↗