Biomedical subjects
K C Copeland
Publications and source records attributed to K C Copeland.
Secretion of prolactin and insulin-like growth factor I by decidual explant cultures from pregnancies complicated by intrauterine growth retardation.
OBJECTIVES: Prolactin and insulin-like growth factor I secretion elsewhere in the uterus have been shown to decrease when tissue-specific growth is limited. We investigated their secretion by decidual explant cultures from pregnancies complicated by fetal intrauterine growth retardation. STUDY DESIGN: Explant cultures from 13 pregnancies complicated by intrauterine growth retardation and 12 control pregnancies were established in minimal essential medium and media was harvested after 24 hours of culture. Prolactin and insulin-like growth factor I concentrations were determined by radioimmunoassay. Total protein in the media was also measured. Data were analyzed by analyses of variance and linear regression. RESULTS: Decidual prolactin secretion in the pregnancies with intrauterine growth retardation was reduced to 109 +/- 31 ng/100 mg tissue per 24 hours compared with 254 +/- 51 ng in the controls (p = 0.01). Insulin-like growth factor I secretion was reduced to 1.9 +/- 0.6 ng/100 mg tissue per 24 hours from 7.1 +/- 0.9 ng/100 mg in the controls (p < 0.0001). Total protein secretion did not differ between the two groups. Decidual prolactin and insulin-like growth factor I secretion had a highly significant positive correlation (r = 0.71, p = 0.0001). CONCLUSIONS: Our data show that two protein hormones secreted by the maternal decidua are dramatically reduced in intrauterine growth retardation and warrant further investigation into their roles in the intrauterine environment.
Heated dorsal hand vein sampling for metabolic studies: a reappraisal.
The purpose of the current study was to determine the accuracy of a given heated dorsal hand vein (HDHV) measurement in predicting a simultaneous arterial measurement and to validate this technique for use in stable isotope studies. Twenty catheterizations of the femoral artery, femoral vein, and a dorsal hand vein were performed in 13 healthy male subjects. Simultaneous blood samples were obtained from all three sites during primed continuous infusions of L-[1-13C]leucine (Leu) and L-[ring-2H5]phenylalanine (Phe) in the postabsorptive state, with or without intravenous glucose infusion. Relationships were examined by linear regression analysis, with 95% prediction intervals for femoral arterial values determined using the HDHV-derived values as independent variable. Glucose concentrations and isotopic enrichments of ketoisocaproate (KIC), Leu, and Phe were similar in HDHV- and arterial-derived blood, with slopes between 0.9414 and 1.0008, intercepts not different from zero, and r2 values of 0.7613 or greater (P < 0.05). Intercepts for KIC, Leu, and Phe concentrations all were different from zero (P < 0.05), and slopes ranged between 0.7560 and 0.8625. For each analysis the HDHV sample correlated better with the femoral arterial sample than with the femoral venous sample. These data support the use of HDHV sampling as a surrogate for direct arterial sampling but document significant limitations in the technique.
Recurrent ovarian cysts in childhood: diagnosis of McCune-Albright syndrome by bone scan.
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46,XX gonadal dysgenesis with epibulbar dermoid.
Pure gonadal dysgenesis with 46,XX genotype is a rare abnormality with unknown etiology. Although sensorineural deafness has been described with 46,XX gonadal dysgenesis, the majority of reported cases of 46,XX gonadal dysgenesis have no associated physical abnormalities. We report a patient with 46,XX gonadal dysgenesis associated with epibulbar dermoids and preauricular skin tags, the classic ocular and skin manifestations of Goldenhar sequence (oculoauricular vertebral dysplasia). We propose that our patient may represent a new and previously unreported syndrome.
Insulin-like growth factor I in substrate-deprived, growth-retarded fetal rats.
Plasma, amniotic fluid, and tissue concentrations of IGF-I were examined in nutritionally deprived, growth-retarded fetal rats to determine whether IGF-I concentration serves as a marker for nutritional status. Growth retardation was induced by 72 h of maternal fasting. Twenty-three control and 17 growth-retarded fetuses were individually analyzed and compared. Plasma IGF-I concentrations were significantly lower in test compared with control animals (test 56.8 +/- 14.9, control 87.4 +/- 17.5 ng/mL, p less than 0.01). Amniotic fluid IGF-I concentrations were not different (test 14.0 +/- 8.7, control 12.2 +/- 2.6 ng/mL). IGF-I concentrations obtained from both placental and hepatic tissues were lower in test compared with control animals [placenta: test 293 +/- 25 versus control 655 +/- 114 ng/g (p less than 0.001); hepatic: test 173 +/- 38 versus control 230 +/- 51 ng/g (p less than 0.01)]. Reductions in fetal, placental, and hepatic weights in test animals were more closely related to changes in placental IGF-I concentration than to either plasma or hepatic IGF-I concentrations. We conclude that fetal plasma IGF-I is a valuable marker for intrauterine substrate deprivation and that the growth-retarded rat fetus is accurately identified and specifically characterized by a low placental concentration of extractable IGF-I.
Effect of obesity on plasma insulin-like growth factor-I in cancer patients.
Starvation and malnutrition are associated with low concentrations of plasma insulin-like growth factor I (IGF-I). To evaluate the utility of IGF-I as a screening test for malnutrition, we compared plasma IGF-I concentrations with anthropometric measurements of nutritional status in 99 cancer patients. Forty-three percent of patients were overweight and 4 percent were underweight. Log IGF-I correlated negatively with body weight (r = -0.31, P = 0.002), midarm muscle area (MAMA) (r = -0.31, P = 0.001), triceps skinfold thickness (TSF) (r = -0.24, P = 0.03) and body mass index (r = -0.31, P = 0.003). In males plasma IGF-I correlated with TSF but not MAMA; in females IGF-I correlated with MAMA but not TSF, suggestive of a sexual dimorphism between plasma IGF-I and indices of adiposity. We conclude that obesity was far more prevalent than undernutrition, and that plasma IGF-I correlated negatively with indices of adiposity in a gender specific fashion. Because IGF-I is significantly reduced in the obese as well as in the malnourished, measurements of plasma IGF-I are unlikely to be of adequate clinical specificity to serve as a useful screening test for subtle alterations in nutritional status.
Influence of gonadal steroids on rat pituitary growth hormone secretion.
Growth hormone (GH) secretion increases at the time of puberty, and both androgens and estrogens increase the GH response to provocative agents. Little is known, however, with regard to the mechanism or site of action of gonadal steroid-stimulated GH secretion. Using monolayer primary cell culture and radioimmunoassay techniques, insulin-like growth factor I (IGF-I), purified and biosynthetic human GH, 17 beta-estradiol (E2), and testosterone (T) effects on GH release from rat anterior pituitary cells were investigated. Media content of rat GH was measured, both basally and after growth hormone releasing factor (GRF) stimulation. IGF-I at 50 nM concentration inhibited basal rGH release but not in GRF-stimulated cells. E2 (10 pM) stimulated basal secretion of rGH, although higher concentrations did not. High concentrations of T (100,000 pM) caused an increase in GRF-stimulated rGH secretion. Neither purified nor biosynthetic hGH pretreatment influenced subsequent rGH release. These results suggest that IGF-I inhibits and E2 (low dose) and T (high dose) augment rGH release in part at the level of the anterior pituitary.
The relationship between insulin-like growth factor-I, adiposity, and aging.
Aging is associated with both a relative accumulation of body fat and a reduction in growth hormone (GH) secretion. This study was devised to investigate the relationship between plasma insulin-like growth factor-I (IGF-I), an index of GH secretion, and anthropometric indices of body fat in normal subjects of various ages. Somatic and biochemical indices of nutrition were assessed in 107 subjects between the ages of 17 and 83 years who attended an outpatient clinic for general health supervision. Plasma IGF-I correlated negatively with age in both males (r = -.44, P = .001) and females (r = -.40, P = .005). In addition, plasma IGF-I correlated negatively with body mass index (BMI) (r = .35, P = .006), percentage of standard triceps skinfold (TSF) (r = -.26, P = .05), and percentage of standard weight (r = -.35, P = .006) in males, but not in females. Multiple regression analysis indicated that in males, BMI and percentage of standard weight correlated with plasma IGF-I independent of the effect of age. We conclude that adiposity and aging are independently associated with decreased plasma IGF-I concentrations. The negative correlations between indices of adiposity and IGF-I were observed only in males, whereas the age-associated decline in IGF-I was present in both males and females. We speculate that sex differences in the gonadal steroid milieu, combined with declining GH secretion in both sexes, may contribute to the age-associated development of obesity in males.
Influence of physical activity on insulin-like growth factor-I in healthy younger and older men.
To examine the hypothesis that a lower level of physical activity influences the age-related decline in insulin-like growth factor-I (IGF-I), we measured serum concentrations in healthy nonobese younger and older men, characterized for maximal aerobic capacity (VO2 max) and energy expended in leisure time physical activity. To examine the independent influence of physical activity on IGF-I relative to other lifestyle variables, we also determined fat-free weight, percent body fat, body fat distribution (waist to hip and waist to thigh ratios), and habitual caloric intake in our population. IGF-I was 33% lower (P less than 0.01) in older men than in younger men, inversely related to percent body fat (r = -0.55) and indices of upper body fat distribution (waist to hip ratio, r = -0.45; waist to thigh ratio, r = -0.47), and positively related to VO2 max (r = 0.64) and leisure time physical activity (r = 0.45; P less than 0.01). IGF-I was not related to fat-free weight or daily caloric intake. After controlling for the effects of age by multiple regression analysis, VO2 max (r = 0.29) and leisure time physical activity (r = 0.24) were the sole factors independently related to IGF-I (P less than 0.05). Our results suggest that multiple factors contribute to the age-related decline in IGF-I. Lower levels of IGF-I in aging men are related at least in part to diminished physical activity.
Too uptight about tight control?
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Effect of tamoxifen on plasma insulin-like growth factor I in patients with breast cancer.
Human breast cancer cells secrete and have membrane receptors for insulin-like growth factor I (IGF-I), a growth hormone-dependent peptide that stimulates cell replication. However, little is known about plasma concentrations of IGF-I in breast cancer patients. Plasma IGF-I levels are decreased in malnutrition, decline with advancing age, and are influenced by estrogen. We evaluated the effect of the antiestrogen agent tamoxifen on plasma IGF-I in 32 ambulatory breast cancer patients. Treatment with tamoxifen was associated with lower concentrations of plasma IGF-I (0.48 +/- 0.3 unit/ml in treated versus 1.03 +/- 0.6 units/ml in nontreated patients, P less than 0.01). However, patients treated with tamoxifen did not differ from nontreated patients in age, menopause, duration since diagnosis, metastatic disease, recent weight loss, or measures of nutritional status. We conclude that tamoxifen therapy results in a reduction of plasma IGF-I concentration. We speculate that the antitumor action of tamoxifen in breast cancer is due in part to suppression of IGF-I.
Congenital hypopituitarism. With free water intolerance and lack of thymic involution. Early recognition of clinical presentation.
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Bioengineered human growth hormone supports limb regeneration in the hypophysectomized newt Notophthalmus viridescens.
It is well documented that growth hormone (GH) replacement therapy will restore normal limb regeneration to hypophysectomized adult newts. However, it is also known that the GH preparations used in previous reports were contaminated by other pituitary hormones shown to support regeneration when administered free of GH. The recent availability of bioengineered human GH was studied for its ability to restore the regenerative capacity to hypophysectomized newts. Five days posthypophysectomy adult newts were subject to forelimb amputation distal to the elbow. Animals were divided into three groups (n greater than 20). Each received one of three GH preparations: pituitary-derived bovine GH, pituitary-derived human GH, or bioengineered human GH. GH was administered via intraperitoneal injection (0.029 IU/50 microliters) on alternate days for either the first 5 days (total of 3 injections) or for 35 days (total of 18 injections). Pituitary-intact and hypophysectomized control newts were subjected to forelimb amputation and injected with hormone diluent. All newts that received GH demonstrated normal limb regeneration to the early digitiform stage by 35 days postamputation. None of the hypophysectomized control newts showed any evidence of regeneration. We conclude that GH alone can restore the ability to undergo normal limb regeneration to hypophysectomized newts.
Sweat tests in patients with diabetes insipidus.
Increased sweat chloride concentrations have been reported in patients with nephrogenic (NDI) but not central diabetes insipidus (CDI). To determine whether false-positive sweat tests also occur in CDI, six subjects with CDI had plasma electrolytes, osmolatities, and sweat tests performed before and after water deprivation. All subjects were hyperosmolar after dehydration (287 +/- 2.0 and 296 +/- 3.2 mosm/kg, plasma osmolality before and after dehydration, respectively; p = 0.02). Sweat chloride concentrations before and after dehydration were not different, and no positive sweat tests were observed. Sweat chloride concentrations after dehydration did not correlate with the degree of dehydration as assessed by either plasma sodium or plasma osmolality. We conclude that increased concentrations of chloride in sweat are not typically found in dehydrated subjects with CDI, although they have been reported in subjects with the nephrogenic form.
Effects of acute high dose and chronic low dose estrogen on plasma somatomedin-C and growth in patients with Turner's syndrome.
Previously reported data with regard to the effects of estrogen on plasma somatomedin-C (Sm-C) concentrations are contradictory. This study was designed to evaluate, in the same subjects with Turner's syndrome, the effects of both acute high dose and chronic low dose estrogen treatment on plasma Sm-C concentrations. Eight girls with Turner's syndrome, aged 10 8/12 to 14 9/12 yr, were admitted to the Clinical Research Center for 3 days. Each received an iv infusion of conjugated estrogens (1.25 or 2.5 mg) in 12 h. Plasma Sm-C and serum GH and estrone levels were measured before, during, and after the infusion. The mean serum concentrations in the girls who received 1.25 mg conjugated estrogen increased from less than 222 pmol/L to 1905 +/- 240 (+/- SE), 825 +/- 166, and 296 +/- 74 pmol/L immediately after, 12 h after, and 24 h after completion of the infusion, respectively. Serum GH concentrations were undetectable (less than 1 microgram/L) before, during, and after the infusion. The mean plasma Sm-C concentrations decreased significantly (P = 0.02) after the infusion was terminated, falling from a mean basal value of 1.3 +/- 0.2 (+/- SE) to a nadir of 0.6 +/- 0.1 U/mL 12 h after completion of the infusion. The same girls then were treated with low dose (5 micrograms ethinyl estradiol) estrogen therapy for 9-14 months. Seven of the eight girls had an increase in growth rate. The mean growth rate increased from 2.0 +/- 0.5 to 5.4 +/- 0.8 and 3.8 +/- 0.4 cm/yr from 3 to 6 (P less than 0.05) and from 9 to 14 months of treatment, respectively. Individual variability was great, however, and two of the eight girls never grew at a rate faster than 4.0 cm/yr during therapy. No consistent alteration in bone age relative to chronological age was found, and the growth response was not predicted by the bone age at the beginning of treatment. Mean plasma Sm-C concentrations did not change. These studies demonstrated a growth spurt in girls with Turner's syndrome during chronic low dose estrogen therapy, which was not associated with any change in plasma Sm-C concentrations. Acute high dose iv estrogen infusion resulted in a significant decline in plasma Sm-C concentrations. These results support the concept that in girls with Turner's syndrome the plasma Sm-C response to estrogen is influenced by multiple, as yet undefined, factors.
Mercury poisoning and acrodynia.
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Variations in normal sexual development.
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