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Biomedical subjects

D K Snyder

Publications and source records attributed to D K Snyder.

At least 37 records · Page 2Linked to original sources
PubMed1988

Treatment of obese, diet-restricted subjects with growth hormone for 11 weeks: effects on anabolism, lipolysis, and body composition.

We found in a previous study that injections of GH for 3 weeks caused nitrogen conservation despite restriction of intake to 24 Cal (100 kJ)/kg ideal BW (IBW). To determine the effects of longer periods of treatment and further caloric restriction on nitrogen balance, lipolysis, and body composition, 20 obese (30-67% over IBW) subjects (16 women and 4 men; 20-54 yr old) were fed a diet of 18 Cal (75 kJ)/kg IBW with 1.2 g protein/kg IBW daily for 13 weeks. During weeks 2-12, 10 subjects received injections of recombinant methionyl GH (0.1 mg/kg IBW every other day), and the other 10 sex-, age-, and weight-matched subjects were given injections of saline. There were no significant differences between the two groups in total weight loss [GH, 13.9 +/- 3.0 (+/- SD) kg; saline, 15.2 +/- 3.8 kg ) or the percentage of body fat lost (GH, 8.1 +/- 2.4%; saline, 7.5 +/- 1.5%), although GH injection caused a significant acute increment in serum FFA concentrations (GH, 0.53 +/- 0.37 mmol/L; saline, 0.08 +/- 0.22 mmol/L; P less than 0.001) throughout the study. This acute lipolytic response to GH decreased significantly, from 0.86 +/- 0.32 mmol/L on day 1 of GH treatment to 0.35 +/- 0.41 mmol/L by day 35 of GH injection (P less than 0.01). Nitrogen balance was significantly more positive in the group receiving GH during the first 33 days of the GH injection period [GH, +0.07 +/- 1.82 g/day (+5.0 +/- 130.0 mmol/day); saline, -1.91 +/- 1.10 g/day (-136.3 +/- 78.5 mmol/day); P less than 0.001]. During the last 44 days of GH injection, however, the nitrogen balance in the two groups was similar [GH, -0.90 +/- 1.65 g/day (-64.2 +/- 117.8 mmol/day); saline, -1.08 +/- 0.95 g/day (-77.1 +/- 67.8 mmol/day); P = NS]. Mean plasma insulin-like growth factor I (IGF-I) concentrations rose from a basal value of 1.6 +/- 0.8 to 2.9 +/- 1.2 U/mL by 48 h after the first GH injection and ranged subsequently from 3.2 +/- 1.3 to 4.9 +/- 3.3 U/mL during GH injection (P less than 0.001). In contrast, the mean IGF-I concentration did not change in the group that received saline. Dietary restriction during the first week of study caused serum T3 concentrations to decline in both groups.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1988

Radioimmunoassay of a 26,000-dalton plasma insulin-like growth factor-binding protein: control by nutritional variables.

Insulin-like growth factor I (IGF-I) is a peptide growth factor that circulates bound to carrier proteins. One form of carrier protein (mol wt, approximately 26K) is not believed to be GH dependent, is relatively unsaturated, and modulates the cellular response to IGF-I. This study was undertaken to determine the variables that control the plasma concentration of this protein, which was measured using a specific RIA. The mean plasma 26K IGF-binding protein (IGF-BP) concentration in 15 normal fasting subjects at 0800 h was 9.4 +/- 4.4 (+/- SD) micrograms/L. The mean value in GH-deficient patients was increased to 19.5 +/- 10.1 micrograms/L (n = 60; P less than 0.05), and it was 7.3 +/- 4.3 micrograms/L in patients with acromegaly (n = 31). The GH dependency of these changes is further supported by the observation that subjects who received GH injections had a 51% reduction in their fasting values. Nutritional intake appeared to be a more important controlling variable than GH. During an overnight fast plasma 26K IGF-BP values increased approximately 4-fold in 6 normal subjects. After 2 days of fasting, the mean value in 7 obese subjects rose progressively from 6.5 +/- 2.3 to 11.7 +/- 5.4 micrograms/L (P less than 0.001), and it increased further to 19.2 +/- 5.9 micrograms/L by day 4 of fasting; after 2 days of refeeding it returned to the prefasting level of 6.8 +/- 1.9 micrograms/L. Likewise, ingestion of a standard test meal resulted in a significant decrease in mean plasma 26K IGF-BP from a fasting value of 8.4 +/- 2.9 to 5.6 +/- 2.8 micrograms/L 4 h postprandially (P less than 0.05). In summary, the plasma concentrations of the 26K IGF-I-BP fluctuate widely in response to dietary manipulation, whereas GH status appears to be a secondary controlling variable.

Adult↗
PubMed1987

Convergent validity of observational and self-report measures of marital interaction.

Previous research findings have challenged the validity of couple's self-reports of their communication effectiveness. In the present study, observational ratings of couples' communication and spouses' self-reports on a multidimensional measure of marital interaction were obtained for a sample of 30 clinic and 12 nonclinic couples. The convergent validity of these two approaches to marital assessment was evaluated by identifying significant correlations for the total sample and for clinic and nonclinic couples, separately. In contrast to previous investigations of this nature, substantial convergence was obtained between the Couples Interaction Scoring System (CISS) and the Marital Satisfaction Inventory (MSI). In general, convergence of the two approaches was stronger for couples in marital therapy. Implications of these findings for clinical assessment and research with nonclinic populations are discussed.

Adaptation, Psychological↗
PubMed1987

Growth hormone administration conserves lean body mass during dietary restriction in obese subjects.

Because weight-reducing diets result in loss of lean body tissue as well as fat, we sought to determine whether injections of GH might facilitate the preservation of nitrogen and accelerate the loss of body fat during dietary restriction. The dietary intake of 8 obese subjects was restricted to 24 Cal/kg ideal BW and 1 g protein/kg for 11 weeks. During weeks 3-5, 4 subjects were given a total of 10 im injections of recombinant methionyl human GH, 1 morning injection every 48 h in a dosage of 0.1 mg/kg ideal BW. The other 4 subjects were given injections of vehicle. During weeks 8-10, the subjects who had received GH previously were given vehicle and vice versa. While receiving GH injections the mean daily nitrogen deficit [0.35 +/- 2.14 (+/- SD) g/day] was significantly less than the loss during injection of vehicle (2.21 +/- 1.45 g/day; P less than 0.001). Although three of six subjects lost 190% more fat (as determined by hydrostatic weighing) while receiving GH, the difference in group mean fat loss during GH injection was not significantly greater than that during injection of vehicle (3.06 +/- 1.39 kg lost with GH vs. 2.64 +/- 1.08 kg lost with vehicle; P = NS). In parallel with the changes in nitrogen balance, GH produced a significant increase in the mean plasma somatomedin-C/insulin-like growth factor I concentration. From a mean pretreatment value of 1.06 +/- 0.28 U/mL, a maximal value of 3.20 +/- 1.60 U/mL was achieved after 12 days of GH injection (P less than 0.001). Somatomedin-C/insulin-like growth factor I concentrations did not change during injection of vehicle. During GH injection weight loss was attenuated because of fluid retention. If weight loss was determined 1 week after the end of GH administration, however, the total weight loss (3.42 +/- 1.73 kg) was not significantly different from that during the 3 weeks of vehicle administration and the following week (4.16 +/- 1.30 kg). Fasting blood glucose and serum insulin concentrations did not change during GH administration, and no glycosuria was detected in morning urine samples. Short term GH administration is effective in decreasing the loss of lean body mass in individuals ingesting restricted diets. However, fat loss was not accelerated.

Adipose Tissue↗
PubMed1984

Current controversies: exercising during pregnancy.

The current emphasis on physical fitness has motivated many women to participate in a variety of exercise programs. Increased participation by pregnant women is also occurring in the form of self-directed activities and/or as recommended by physicians in an effort to shorten labor and improve pregnancy outcome. Whether exercise improves or presents a potential hazard to the mother and fetus is a concern. The implications for the "trained" woman as well as the "untrained" exerciser are unclear and need definitive study.

Adolescent↗
PubMed1984

Altered pressor responses in long-term nitrendipine treatment.

The effect of long-term treatment with nitrendipine on systemic pressor responses to norepinephrine (NE) and angiotensin II (AII) was evaluated in 11 subjects with mild, uncomplicated hypertension. Pressor responses to NE and AII were measured at the end of a 4-wk placebo period and after 5 wk treatment with nitrendipine (final dose 16 mg twice daily; range 5 to 20 mg/day) or placebo. In subjects who received nitrendipine, clinic supine blood pressure was reduced from 152 +/- 12/96 +/- 4 mm Hg to 134 +/- 11/84 +/- 5 mm Hg and pressor responses to NE but not to AII were attenuated. Endogenous plasma levels of NE and renin activity were not changed by nitrendipine. Data suggest that noradrenergic blood pressure control mechanisms depend more on cellular calcium transport than do AII-mediated ones and may help explain the greater effectiveness of calcium entry blockers in the treatment of low-renin hypertension.

Adult↗
PubMed1984

Increased serum and urinary N-acetyl-beta-D-glucosaminidase activity in human hypertension: early indicator of renal dysfunction.

The pathophysiologic significance of increased serum and urinary N-acetyl-beta-D-glucosaminidase (NAG) activity in hypertension was investigated. The subjects were 32 male patients, aged 40-65 years, with mild or borderline, uncomplicated hypertension and 26 age-matched, male normotensive volunteers. Compared to values in control subjects, NAG activity in the serum, spot and 24-hour urine samples of hypertensive subjects was increased (p less than 0.01). Serum NAG activity in hypertensive subjects was inversely correlated with glomerular filtration rate (r = -0.49, p less than 0.01, N = 31) and renal plasma flow (r = -0.56, p less than 0.02, N = 19) and positively correlated with mean arterial blood pressure (r = 0.40, p less than 0.05). The elevation of serum NAG activity in hypertension is a biochemical marker of the reduction in glomerular filtration rate and renal plasma flow.

Acetylglucosaminidase↗
PubMed1983

Determinants of sexual dissatisfaction in sexually distressed couples.

Forty-five couples seeking sex therapy were administered a 15-item symptom checklist regarding both specific sexual dysfunctions and more general interpersonal difficulties, along with an objective criterion measure of overall sexual dissatisfaction. For males, the most common complaint involved too infrequent intercourse, followed by failure of their partner to reach orgasm and concern with their own sexual adequacy. For women, five of the six most prevalent complaints involved difficulty with becoming sexually aroused or reaching orgasm. For both sexes, the incidence of specific sexual dysfunctions was considerably lower than for more general interpersonal difficulties. For both males and females, important determinants of sexual distress included the partner's lack of response to sexual requests, infrequent intercourse, lack of affection for the partner, and the absence of specific sexual dysfunctions in oneself. In addition, males' sexual dissatisfaction was strongly influenced by their wives' failure to reach orgasm, whereas wives were more responsive to concerns regarding their own sexual adequacy.

Adult↗
PubMed1983

Increased renal plasma flow in long-term enalapril treatment of hypertension.

The renal effects of long-term antihypertensive treatment with enalapril were evaluated in 34 subjects (age, 53 yr; range, 27 to 65) with mild, uncomplicated hypertension. After receiving placebo for 4 wk, subjects were randomly assigned to groups receiving incremental doses of enalapril (10, 20, or 40 mg/day for 4 wk each) in a single morning dose or two divided doses, or of placebo. One subject who received enalapril developed acute renal failure by the end of the study. There was no evidence of glomerular or tubular damage in the other subjects; as measured by 24-hr urinary protein excretion, urinary activity of N-acetyl-beta-D-glucosaminidase, and uric acid clearance. During treatment with enalapril, renal plasma flow (measured with 131I-iodohippurate sodium) and glomerular filtration rate increased by 12.1% and 6.8%. Changes in renal plasma flow correlated inversely with age and final mean arterial pressure and correlated positively with initial plasma renin activity of subjects. Except for an occasional idiosyncratic adverse reaction, enalapril is a safe and effective antihypertensive drug with the unique ability to increase renal function despite a fall in renal perfusion pressure.

Acute Kidney Injury↗
PubMed1983

Predicting couples' response to brief directive sex therapy.

Pretreatment Marital Satisfaction Inventory (MSI) scores for 26 couples entering brief directive sex therapy were correlated with posttreatment ratings of dissatisfaction with the frequency of intercourse and individuals' lack of affection for their partner. Six of 11 MSI scores obtained at intake predicted termination ratings of sexual distress, and five scales predicted posttreatment ratings of marital distress. Separate multiple regression analyses for both outcome criteria permitted the delineation of separate MSI predictors for these two distinct components of couples' therapeutic response. Results confirm previous implications of marital distress as a moderator of couples' response to sex therapy.

Adult↗
PubMed1981

Empirical descriptors of unelevated MMPI profiles among chronic pain patients: a typological approach.

The task of the clinician in evaluating the possible role of psychological factors in patients' pain disability is a most difficult one. This task becomes even more arduous when confronted with unelevated MMPI profiles from patients in whom physical findings are minimal or absent. The current study employs a multivariate, quantitative taxonomic procedure to delineate homogeneous subgroupings of chronic pain patients who meet this criterion. Subsequent analysis of base rate data for subgroups across a broad range of pain-related variables provide an actuarial basis of assessment of psychological factors within this population. Results indicate that of five subtypes identified, only one group of patients, who comprise 9% of the total sample, are likely to be free of significant psychological components in their pain behavior. Implications for clinical interpretation and future research are discussed.

Humans↗