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K Day

Publications and source records attributed to K Day.

44 records · Page 3Linked to original sources
PubMed1986

Insulin stimulation of cyclic AMP phosphodiesterase is independent from the G-protein pathways involved in adenylate cyclase regulation.

The intact rat adipocyte was used to investigate the possibility of common intermediates in the insulin stimulation of cyclic AMP phosphodiesterase and the beta-adrenergic/adenosine regulation of adenylate cyclase. A five minute incubation of the isolated adipocytes with insulin produced a 50-100% increase in the phosphodiesterase activity found in the particulate fraction of homogenates. The insulin stimulation was not impaired by the presence of either agonist or antagonists of the inhibitory adenosine receptor which acts on adenylate cyclase. Phosphodiesterase activation by insulin was also observable above the level of stimulation produced by the beta-adrenergic agent isoproterenol and forskolin. The validity of the enzyme activity measurements was supported by measurements of the hormonal actions on cyclic AMP levels within the cells. Possible crossover between the adenylate cyclase and phosphodiesterase regulation systems at a post-receptor site was investigated using adipocytes exposed to bacterial toxins specific for the modification of guanine nucleotide binding proteins. Both cholera toxin, which irreversibly activates Gs and pertussis toxin which inactivates Gi caused some stimulation of the phosphodiesterase activity and suppressed activation by isoproterenol, but neither toxin prevented the insulin stimulation of cyclic AMP phosphodiesterase. These results suggest, while common components may participate in the beta-adrenergic stimulation of both adenylate cyclase and phosphodiesterase, the mechanism of insulin activation of the phosphodiesterase does not involve the components of adenylate cyclase regulation.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1985

Comparison of stress digital ventriculography, stress thallium scintigraphy, and digital fluoroscopy in the diagnosis of coronary artery disease in subjects without prior myocardial infarction.

Exercise thallium scintigraphy is often used for the diagnosis of coronary artery disease (CAD). Exercise digital subtraction ventriculography and digital subtraction fluoroscopy are new diagnostic procedures with roles that have not been determined. To compare the relative accuracies of the digital techniques with thallium scintigraphy, 97 consecutive patients without myocardial infarction underwent all 3 tests on the day before their scheduled coronary angiograms. Forty-two patients had CAD (more than 50% diameter narrowing of 1 major artery). A fixed or reversible perfusion defect defined an abnormal thallium test response and a segmental wall motion abnormality at rest or with exercise defined an abnormal digital ventriculographic response. Any visualized coronary calcific deposit defined an abnormal digital fluorographic response. The sensitivities of digital fluoroscopy (86%) and digital ventriculography (79%) were significantly higher than the sensitivity of thallium (62%) (p less than 0.05). The specificity of thallium (82%) was not significantly higher than that of either digital ventriculography (72%) or fluoroscopy (67%). The diagnostic accuracies of digital fluoroscopy, digital ventriculography, and thallium were 75%, 75% and 73%, respectively. A logistic regression model showed that thallium and digital fluoroscopy were more accurate in younger patients, whereas digital ventriculography was more sensitive in hypertensive persons and in those not taking beta-blocking drugs. The choice of test depends on disease prevalence, clinical variables (such as age and hypertension) and the importance of functional information obtained from stress testing.

Age Factors↗
PubMed1985

Psychiatric disorder in the middle-aged and elderly mentally handicapped.

In a study of 357 long-stay hospital residents aged 40 years and over, 30% had significant psychiatric disorder, while a retrospective survey of 215 new admissions over a seven-year period to a psychiatric unit for the mentally handicapped revealed that 20% of patients were aged 40 years and over. Both similarities and differences were found in the overall pattern of disorders between the two groups and a non-handicapped population in a comparable age-range.

Adult↗
PubMedDate not supplied

Developmental expression of vitamin K-dependent gamma-carboxylase activity in zebrafish embryos: effect of warfarin.

Vitamin K-dependent gamma-carboxylation is an essential posttranslational modification required for the functional activity of coagulation proteins such as factors VII, IX, X, and prothrombin. Warfarin, an inhibitor of vitamin K-dependent gamma-carboxylation, was used in earlier work on adult zebrafish to provide evidence for the presence of vitamin K-dependent carboxylase in zebrafish. Here we demonstrate the presence of vitamin K-dependent carboxylase activity in zebrafish by directly assaying the microsomal fraction prepared from adult, unfertilized eggs, and embryos from different developmental stages. Gamma-carboxylase activity was detected both before and after fertilization of embryos and the activity levels remained relatively constant from 6 h postfertilization (hpf) through other advanced stages of development. The expression of activity in the early embryos (0-6 hpf) may be due to the presence of maternal protein since the activity was detected even in the unfertilized eggs. Gamma-carboxylase activity in the eggs as well as early embryos suggested that vitamin K-dependent carboxylase is important throughout development. The detection of vitamin K-dependent carboxylase mRNA by RT-PCR and inhibitor studies using warfarin confirmed these activity results. Further, these studies provide a basis for selecting warfarin-resistant zebrafish mutants in order to find genes regulating gamma-carboxylase activity including the yet unidentified vitamin K-epoxide reductase.

Amino Acid Sequence↗