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Biomedical subjects

J Chipman

Publications and source records attributed to J Chipman.

6 recordsLinked to original sources
PubMed2000

Suppression and recovery of GH secretion after GH injection in non-GH deficient short children.

OBJECTIVE: To identify the effect of exogenous GH on endogenous GH secretion in 48 non-GH deficient short children participating in a placebo-controlled trial of GH therapy on final adult height. DESIGN: Night GH secretion (mean of levels every 20 min from 20.00 to 08.00 h) was evaluated at baseline, 6 months before starting placebo or GH (somatotropin, 0.222 mg/kg/ week, divided into 3 doses each week). At 6 months after starting injections, blood samples for GH were obtained hourly for 24 h after an injection, and every 20 min on each of the next two nights (with no additional placebo or GH injection). RESULTS: IGF-I levels in the treatment group were elevated at 12 and 24 h but not at 36 h compared to the placebo group. Mean GH levels in the placebo group did not vary significantly among the four sampling periods. In the treatment group, the mean serum GH rose to a supraphysiological peak at an average time of 4 h after injection. Subsequently, mean GH level was significantly suppressed compared to placebo on the second night following GH injection, but returned to normal by the third night. CONCLUSION: After 6 months of a thrice weekly GH treatment regimen in non-GH deficient short children, endogenous GH secretion was reduced from 24 to 36 h after injection compared to placebo and returned to control levels by 48 to 60 h after injection.

Child↗
PubMed1985

Restriction fragment length polymorphism of the gene encoding the alpha chain of the human T cell receptor.

Two allelic forms of the T cell antigen receptor alpha chain gene were discerned by restriction fragment length polymorphism (RFLP) employing the T cell antigen receptor alpha chain probe pGA5, and the restriction enzyme Bgl II. Analysis revealed that the polymorphic fragments are detected by a probe specific for the constant region exon of the T cell antigen receptor alpha chain gene. Furthermore, the polymorphic fragments were shown to segregate within families. The two allelic forms yield two homozygous states, 3.2/3.2 and 2.9/2.9, at a frequency of 76.5 and 2.9%, respectively, within the normal population. The heterozygous state was observed in 20.6% of the population. The discovery of allelic forms of both the alpha and beta chains of the T cell antigen receptor genes may provide a unique opportunity to study heritable markers of T cell function in several human diseases.

Bacterial Proteins↗
PubMed1978

Regulation of gonadotropin secretion in Turner's syndrome.

To determine the role of body fat in regulating secretion of luteinizing hormone and follicle-stimulating hormone, we measured both at 20-minute intervals for 24 hours in eight children with Turner's syndrome. The 24-hour mean luteinizing hormone levels varied from 20.2 to 70.5 mlU per milliliter. Total body weight, total body fat and percentage of body fat showed a significant negative correlation with the 24-hour mean luteinizing hormone concentrations (P less than 0.01). The 24-hour mean follicle-stimulating hormone concentrations ranged from 60.4 to 229 mlU per milliliter, with a significant negative correlation between total body fat and percentage body fat and the 24-hour mean concentrations (P less than 0.05). These negative correlations were not mediated by estrogens or androgens.

Adipose Tissue↗
PubMed1978

Luteinizing hormone and follicle-stimulating hormone secretory dynamics in Turner's syndrome.

In eight teenage patients with Turner's syndrome, LH and FSH were measured at 20-min intervals for 24 h. The 24-h mean LH and FSH levels ranged from 20.2-70.5 mIU/ml and 60.4-229 mIU/ml, respectively. There was a significant positive correlation between the individual LH and FSH levels in the eight patients; the common correlation coefficient was 0.449 (P less than 0.001). The 24-h mean estradiol level was measurable in only two of the patients and the 24-h mean testosterone level for the eight patients was 0.10 ng/ml. The mean LH concentration during sleep was significantly higher (P less than .01) than during waking. The mean FSH concentration during sleep was also significantly higher (P less than 0.05) than during waking. The LH and FSH peak levels after LRH were significantly correlated with the 24-h mean LH (r = 0.918; P less than 0.01) and FSH concentrations (r = 0.754; P less than 0.05), respectively.

Adolescent↗
PubMed1978

Studies of gonadotropin-gonadal dynamics in patients with androgen insensitivity.

Four patients with androgen insensitivity had plasma LH and FSH measured at 20-min intervals for 24 h and at 15- to 30-min intervals for 3 h after the injection of LRH. Twenty-four-hour mean testosterone (T), estradiol, and androstenedione (delta 4) levels were also measured. Patients with androgen insensitivity had significantly elevated LH levels (P less than 0.05) and an increase in the number of LH secretory episodes (P less than 0.001) compared to normal subjects. The amplitude of the LH secretory episodes, expressed as the absolute increment, was significantly higher than normal controls (P less than 0.005). The LH response to LRH (absolute increment) was twice that of normal, but was not significantly different from normal subjects. The 24-h mean FSH levels were normal in three of the patients and elevated in one. This patient had the mildest degree of androgen insensitivity on clinical exam and the greatest degree of testicular atrophy. The 24-h mean T, estradiol, and delta 4 levels were higher than normal, but only the delta 4 was significantly increased (P less than 0.05). To determine if the elevated LH levels were in response to a decrease in the free T level, we measured T-binding capacity (TBG), TBG was higher than normal controls but was not significantly different, suggesting that elevated LH levels were probably in response to a decrease in T action at the hypothalamic-pituitary level. This was further supported by the inability of prolonged dihydrotestosterone administration to affect LH secretion in one of the patients with the Reifenstein syndrome.

Adolescent↗