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Biomedical subjects

J Barton

Publications and source records attributed to J Barton.

At least 91 records · Page 5Linked to original sources
PubMed1977

Unusual pulmonary vasodilator activity of 13,14-dehydroprostacyclin methyl ester: comparison with endoperoxides and other prostanoids.

Microsomes from stomach fundus and blood vessels transform the endoperoxide, PGH2, into a newly discovered unstable substance, PGI2, that relaxes arterial strips and inhibits platelet aggregation. 13,14-Dehydro-PGI2 methyl ester, a newly synthesized, stable PGI2 analog, was found to have potent vasodilator activity in the feline and simian pulmonary vascular bed. The PGI2 analog decreased lobar arterial perfusion pressure in the intact cat and monkey. Because pulmonary blood flow was held constant and left atrial pressure was unchanged, the decrease in perfusion pressure reflects a decrease in pulmonary vascular resistance. The dilator response was unusual in that it persisted for 10-12 min, whereas the response to PGE1, the only other vasodilator prostaglandin in the mature animal, persisted for only 1-2 min. The dilator response to the PGI2 analog was enhanced when pulmonary vascular resistance was increased. This substance had less effect on cardiac output and aortic pressure than PGE1, whereas it was a more potent pulmonary vasodilator. These data demonstrate that prostacyclin-like substances possess novel vasodilator activity in the pulmonary circulation and suggest a therapeutic use in the treatment of pulmonary hypertensive diseases.

Animals↗
PubMed1977

Synthesis of 13,14-dehydroprostacyclin methyl ester: a potent inhibitor of platelet aggregation.

The structure of the most recently discovered, biologically highly active prostaglandin, PGI2 or prostacyclin, is correctly predicted on biogenetic grounds, and a general synthesis starting with prostaglandins of the F2alpha series is reported. Starting with the biologically active 13,14-dehydro-PGF2alpha, the synthesis involves formation of a 5-bromo-6,9alpha-epoxy derivative, followed by esterification and dehydrobromination of the methyl ester to form the prostacyclin structure. The stereochemistry at C-5 and C-6 of all reported products is assigned on the basis of experimental findings and mechanistic reasoning. 13,14-Dehydroprostacyclin methyl ester is considerably more stable at pH 7.5 than prostacyclin. It inhibits platelet aggregation induced by a variety of agents and causes an increase in renal blood flow in the dog at nanomolar levels.

Animals↗
PubMed1976

Deliberate self-harm: a follow-up study of 279 patients.

Two-hundred-and-seventy-nine patients (103 men, 176 women) were followed-up 1-2 years after an act of non-fatal deliberate self-harm. Of 155 patients offered a psychiatric out-patient appointment at the time, only 68 completed the treatment. A further act of deliberate self-harm was committed by 26 men and 41 women within twelve months. The factors most highly associated with repetition were previous psychiatric treatment, a previous act of deliberate self-harm, and a criminal record. These factors held good for a separate series of patients. Significantly more repeaters received prolonged psychiatric care after the initial episode of deliberate self-harm. The implications of these findings for the clinical management of such patients are discussed.

Adult↗
PubMedDate not supplied

Purification and physical-chemical characterization of hepatic stimulator substance.

Hepatic stimulator substance is a liver growth stimulator derived from the hepatocyte cytosol of weanling or regenerating adult rat livers. The present paper reports the almost 9,000-fold purification of hepatic stimulator substance with an approximately 100,000-fold increase in specific growth stimulator activity. Purification steps included heating at 95 degrees C for 15 min, 40% cold ethanol precipitation, passage over Procion Red HE3B, DEAE cellulose and Sephadex G75 columns and gel filtration and reverse-phase fast protein liquid chromatography techniques. As little as 27 ng per ml of the purest material produced a 2-fold stimulation in the standard HTC cell activity assay. Further studies indicate that hepatic stimulator substance is a highly negatively charged protein and that disulfide bonds or a complex tertiary structure are not essential to its activity. Hepatic stimulator substance is stable over a wide range of pH's and temperatures. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis with silver stain revealed 1 major band at 12,400 daltons and 1 minor band at 17,500 daltons.

Animals↗
PubMedDate not supplied

Determination of non-bilayer phospholipid arrangements and their antibodies in placentae and sera of patients with hypertensive disorders of pregnancy.

Studies suggest that preeclampsia (PE) originates in the placenta and is associated with deficient trophoblast invasion of spiral arteries. The direct cause remains unknown, but preeclampsia is often associated with circulating factors that can induce generalized endothelial dysfunction. Antiphospholipid antibodies (APA) in circulation are also associated with vascular diseases. Although the quantification of APA is not currently used as a prognostic of the risk of PE, studies suggest that thrombophilias play a role in PE pathogenesis. In fact, the pathology of placentae from PE and Antiphospholipid syndrome patients is similar; atherosis, thrombosis and infarction, and endothelium activation represent the pathological mechanisms. We identified a new antibody which recognizes non-bilayer phospholipid arrangements (NPA) in membrane models and in cell membranes in vivo, and which triggered an autoimmune-like disease in mice. We evaluated the presence of NPA in the placentae and in sera, and whether NPA induced NPA antibodies in patients with hypertensive disorders of pregnancy (HDP). Results showed increased levels of NPA in the syncytiotrophoblast, extravillous cytotrophoblast, syncytial knots and the amnion epithelial cell membranes of the placenta, as well as increases in NPA and NPA antibodies in sera from HDP patients, when compared with controls. This suggests that NPA derived from placenta could be one of multiple factors associated with pregnancy pathologies.

Antibodies, Antiphospholipid↗
PubMedDate not supplied

Body image issues for children and adolescents with burns.

Body image is a far-reaching, multidimensional, dynamic concept. Because burn injuries threaten the integrity of both the physical and psychologic identity, body-image issues related to burn injuries appear to be a meaningful area of investigation. Little research has been done to directly assess body-image issues for children and adolescents with burns. We reviewed the general findings that body-image adaptation occurs and is influenced by gender, social support, burn severity, overall adjustment, and developmental stage. It is suggested that body-image revision, if it occurs, is largely successful, but body-image issues may not be directly related to psychosocial adjustment after a burn injury.

Adaptation, Psychological↗
PubMedDate not supplied

Advancing versus delaying shift systems.

Two hundred and sixty-one shiftworkers from a range of UK industrial and service organizations, took part in a study to determine the impact of the direction of shift rotation on the health and well-being of the individuals concerned. All the systems were continuous, rotating over three shifts. Systems were classified according to whether they delayed (i.e., rotated in a forward direction) or advanced (i.e., rotated in a backward direction). In addition, advancing systems were divided into those which incorporated a quick return (i.e., a break of only 8 h when changing from one shift to another) and those which did not. The results add some support for the use of delaying as opposed to advancing systems, and highlight the detrimental effects of incorporating a quick return into an advancing system.

Adult↗
PubMedDate not supplied

Does the 'forbidden zone' for sleep onset influence morning shift sleep duration?

Shiftwork researchers have concentrated on the problems on the night shift, and have tended to neglect the truncation of sleep that can occur before morning, or 'early', shifts. We examined the sleep timing and duration between morning shifts of shiftworkers on a variety of shift systems. The extent of morning shift sleep truncation depended very largely on the time at which individuals had to leave home. Further, there was some suggestive evidence that the failure of individuals to compensate by going to sleep earlier was not simply due to social pressures to stay up. Rather it would appear to have depended, at least in part, on the biological clock determined 'forbidden zone' for sleep that occurs shortly before habitual sleep onset.

Adult↗
PubMedDate not supplied

The relationship between coping strategies and GHQ-scores in nurses.

This paper discusses the development of a situation specific questionnaire for measuring coping with shiftwork. Previously, no standardized measure appears to have been developed, even though coping behaviour is considered to be an important factor in determining tolerance to shiftwork. The results from this study indicated that the present questionnaire may have some potential. Its psychometric qualities were relatively good. Coping scores were related to psychological health, measured by GHQ-12. Analysis of variance showed a main effect of only one of the subscales (disengagement strategies) on GHQ and also a reliable interaction between disengagement and engagement on GHQ-scores. Further research into the effect of coping strategies on shiftwork tolerance is suggested.

Adaptation, Psychological↗