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C St Clair

Publications and source records attributed to C St Clair.

13 recordsLinked to original sources
PubMed2001

Cortisol and GH secretory dynamics, and their interrelationships, in healthy aged women and men.

We studied 130 healthy aged women (n = 57) and men (n = 73), age 65-88 yr, with age-related reductions in insulin-like growth factor I and gonadal steroid levels to assess the interrelationships between cortisol and growth hormone (GH) secretion and whether these relationships differ by sex. Blood was sampled every 20 min from 8:00 PM to 8:00 AM; cortisol was measured by RIA and GH by immunoradiometric assay, followed by deconvolution analyses of hormone secretory parameters and assessment of approximate entropy (ApEn) and cross-ApEn. Cortisol mass/burst, cortisol production rate, and mean and integrated serum cortisol concentrations (P < 0.0005), and overnight basal GH secretion (P < 0.05), were elevated in women vs. men. Integrated cortisol concentrations were directly related to most measures of GH secretion in women (P < 0.01) and with mean and integrated GH concentrations in men (P < 0.05). Integrated GH concentrations were directly related to mean and integrated cortisol levels in women (P < 0.005) and men (P < 0.05), with no sex differences. There were no sex differences in cortisol or GH ApEn values; however, the cross-ApEn score was greater in women (P < 0.05), indicating reduced GH-cortisol pattern synchrony in aged women vs. men. There were no significant relationships of integrated cortisol secretion with GH ApEn, or vice versa, in either sex. Thus postmenopausal women appear to maintain elevated cortisol production in patterns that are relatively uncoupled from those of GH, whereas mean hormone outputs remain correlated.

Aged↗
PubMed2001

Effects of GH and/or sex steroid administration on abdominal subcutaneous and visceral fat in healthy aged women and men.

Aging is associated with reduced GH, IGF-I, and sex steroid axis activity and with increased abdominal fat. We employed a randomized, double-masked, placebo-controlled, noncross-over design to study the effects of 6 months of administration of GH alone (20 microg/kg BW), sex hormone alone (hormone replacement therapy in women, testosterone enanthate in men), or GH + sex hormone on total abdominal area, abdominal sc fat, and visceral fat in 110 healthy women (n = 46) and men (n = 64), 65-88 yr old (mean, 72 yr). GH administration increased IGF-I levels in women (P = 0.05) and men (P = 0.0001), with the increment in IGF-I levels being higher in men (P = 0.05). Sex steroid administration increased levels of estrogen and testosterone in women and men, respectively (P = 0.05). In women, neither GH, hormone replacement therapy, nor GH + hormone replacement therapy altered total abdominal area, sc fat, or visceral fat significantly. In contrast, in men, administration of GH and GH + testosterone enanthate decreased total abdominal area by 3.9% and 3.8%, respectively, within group and vs. placebo (P = 0.05). Within-group comparisons revealed that sc fat decreased by 10% (P = 0.01) after GH, and by 14% (P = 0.0005) after GH + testosterone enanthate. Compared with placebo, sc fat decreased by 14% (P = 0.05) after GH, by 7% (P = 0.05) after testosterone enanthate, and by 16% (P = 0.0005) after GH + testosterone enanthate. Compared with placebo, visceral fat did not decrease significantly after administration of GH, testosterone enanthate, or GH + testosterone enanthate. These data suggest that in healthy older individuals, GH and/or sex hormone administration elicits a sexually dimorphic response on sc abdominal fat. The generally proportionate reductions we observed in sc and visceral fat, after 6 months of GH administration in healthy aged men, contrast with the disproportionate reduction of visceral fat reported after a similar period of GH treatment of nonelderly GH deficient men and women. Whether longer term administration of GH or testosterone enanthate, alone or in combination, will reduce abdominal fat distribution-related cardiovascular risk in healthy older men remains to be elucidated.

Abdomen↗
PubMed1999

Interrelationships of spontaneous growth hormone axis activity, body fat, and serum lipids in healthy elderly women and men.

Aging is associated with decreased growth hormone (GH) secretion and plasma insulin-like growth factor-I (IGF-I) levels, increased total and abdominal fat, total and low-density lipoprotein (LDL) cholesterol, and triglycerides, and reduced high-density lipoprotein (HDL) cholesterol. Similar changes in lipids and body composition occur in nonelderly GH-deficient adults and are reversed with GH administration. To examine whether GH/IGF-I axis function in the elderly is related to the lipid profile independently of body fat, we evaluated GH secretion, serum IGF-I and IGF binding protein-3 (IGFBP-3) levels, adiposity via the body mass index (BMI), waist to hip ratio (WHR), dual-energy x-ray absorptiometry (DEXA), and magnetic resonance imaging (MRI), and circulating lipids in 101 healthy subjects older than 65 years. Integrated nocturnal GH secretion (log IAUPGH) was inversely related (P < .005) to DEXA total and abdominal fat and MRI visceral fat in both genders. Log IAUPGH was inversely related to visceral fat in women (P < .005) and men (P < .0001), but was not significantly related to total fat in either gender. In women, log IAUPGH was related inversely to total and LDL cholesterol and positively to HDL cholesterol (P < .008). In men, log IAUPGH was inversely related to total cholesterol and triglycerides (P < .005). In women, HDL cholesterol was inversely related to the WHR (P < .005). In men, triglycerides were positively related (P < .001) to the WHR and DEXA abdominal and MRI visceral fat. Multivariate regression revealed log IAUPGH, but not DEXA total body fat, to be an independent determinant of total (P < .001 for women and P = .01 for men) and LDL (P < .007 and P = .05) cholesterol in both sexes and of HDL cholesterol (P < .005) and triglycerides (P < .03) in women. Log IAUPGH, but not DEXA abdominal fat, was related to total (P < .005 and P < .03) and LDL (P < .03 and P = .05) cholesterol in both genders and to HDL in women (P < .05). Log IAUPGH, but not MRI visceral fat, was related to total cholesterol (P < .03 and P = .05) in women and men. Age, IGF-I, and IGFBP-3 were not significantly related to any body fat or lipid measures, except for a positive correlation of IGF-I with triglycerides in men. Thus, endogenous nocturnal GH secretion predicts total, LDL, and HDL cholesterol levels independently of total or abdominal fat, suggesting that it is an independent cardiometabolic risk factor in healthy elderly people.

Absorptiometry, Photon↗
PubMed1994

Prostacyclin production in acute, chronic, and long-term experimental portal hypertension.

BACKGROUND: Chronic portal hypertension (PHT) is characterized by a high portosystemic shunt (PSS) and increased splanchnic blood flow. It has been suggested that the splanchnic vasodilator, prostacyclin (PGI2), mediates this increased flow. We studied splanchnic PGI2 production both in normal rabbits and in three groups of rabbits after partial portal vein ligation (PVL-PHT): acute (within 30 minutes of ligation), chronic (3 weeks after ligation), and long-term (3 months after ligation) to determine whether increased splanchnic production is a mechanism for the elevated PGI2 in PHT. METHODS: Levels of 6-keto prostaglandin F1 alpha were determined by radioimmunoassay, and splanchnic hemodynamics were measured with Doppler flowmetry in four groups of rabbits: portal normotensive rabbits, and PVL-PHT rabbits 30 minutes, 3 weeks, or 3 months after partial PVL. Splanchnic PGI2 production (PGI2 PROD) was then calculated. RESULTS: Portal pressure and PSS in chronic and long-term groups were significantly elevated in all groups compared with normals (p < 0.001). Splanchnic blood flow initially fell from 84 +/- 4.8 to 37.4 +/- 7 ml/min/100 gm immediately and then rose to 144.7 +/- 9.6 ml/min/100 gm and 137 +/- 15 ml/min/100 gm at 3 weeks and 3 months after ligation, respectively. PGI2 production rose immediately after partial portal ligation from 62 +/- 10 to 164 +/- 4.1 ng/min/100 gm and remained elevated thereafter. CONCLUSIONS: The mechanism for elevated PGI2 in acute PHT is unclear, but in chronic and long-term PHT, it is probably due in part to increased splanchnic PGI2 production.

Acute Disease↗
PubMed1987

Hemodynamic effects of intravenous digoxin in patients with severe heart failure initially treated with diuretics and vasodilators.

The purpose of this study was to assess the hemodynamic effects of intravenous digoxin in patients with New York Heart Association class IV heart failure, who had never previously been treated with digitalis drugs, and who were initially treated only with diuretics and systemic vasodilators to clinical end points of compensation. Eleven male patients, 5 with idiopathic and 6 with ischemic cardiomyopathy, had sinus rhythm and were hospitalized with congestive heart failure not precipitated by an acute ischemic event. All 11 patients were treated with intravenous furosemide and various vasodilators without invasive hemodynamic monitoring for a mean period of 4.3 +/- 2.1 days. This therapy resulted in subjective and objective improvement in all patients as reflected by a significant decrease in heart failure score from 9.5 +/- 2.2 to 2.7 +/- 2.3 (p less than 0.001). When compensation was achieved by clinical criteria, the patients were instrumented and hemodynamics obtained before and serially thereafter for 6 hours after the intravenous administration of digoxin given in two 0.5 mg doses 2 hours apart. In response to digoxin, cardiac index increased from 2.6 +/- 0.7 liters/min per m2 to a peak of 3.3 +/- 0.6 liters/min per m2 (p less than 0.005); left ventricular stroke work index (g X m/m2) increased from 27 +/- 16 to 43 +/- 23 (p less than 0.005) and the ejection fraction (eight patients) increased from 21 +/- 13% to 29 +/- 11% (p less than 0.04). Mean pulmonary capillary wedge pressure decreased from 24 +/- 7 to a minimum of 17 +/- 4 mm Hg (p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1985

Short- and long-term treatment of stable effort angina with nicardipine, a new calcium channel blocker: a double-blind, placebo-controlled, randomised, repeated cross-over study.

This study evaluated 1 year the efficacy of therapy with nicardipine in patients with chronic stable angina pectoris. Twenty-five male patients were entered. After a placebo run-in phase, the patients received nicardipine 30 mg, nicardipine 40 mg, and placebo, three times daily given in random, double-blind manner for 8 weeks. A double-blind, cross-over study comparing nicardipine with placebo was then undertaken. After 5 months of open treatment with nicardipine 90 or 120 mg day-1, patients received either placebo or nicardipine for 3 weeks, each followed by the alternative treatment for an additional 3 weeks and further open-label treatment with nicardipine for another 3-5 months. There were no significant changes in the PR, QRS or QT intervals, or in the QRS pattern during the short-term and long-term studies. There were no significant differences in mean heart rate after nicardipine compared with baseline. During treatment with nicardipine 120 mg day-1, patients reported significantly fewer anginal attacks compared with placebo, and nitroglycerin consumption also decreased. Nicardipine increased treadmill time, time to onset of angina, and time to one mm ST segment depression. These effects were maintained after 6 months of continued nicardipine therapy. Adverse effects were minor and well tolerated and included headache, dizziness, gastrointestinal upset, flushing paraesthesia and pedal oedema. Abrupt withdrawal of nicardipine at the end of the study resulted in a rapid return of the original symptoms but without further deterioration from the baseline measurements. Nicardipine was effective in the treatment of stable effort angina pectoris; this benefit was maintained for the entire year of treatment.

Adult↗
PubMedDate not supplied

Rural nurses as self-directed learners: overcoming obstacles to continuing education.

Evaluation of a fieldtest of a self-directed learning (SDL) program included assessing rural nurses' self-perceived competencies in this method and loci of control for motivation. A significant negative relationship occurred between high scores for learner skills and internal motivation ratings. Sixty-two percent rated themselves above the mean as self-directed learners regardless of perceived loci of control in the stressful rural practice environment. SDL can offer an alternative way to meet continuing education needs of rural nurses in their efforts to overcome the many obstacles to professional growth in rural practice.

Clinical Competence↗