Gestational diabetes in women living with HIV in Botswana: lower rates with dolutegravir- than with efavirenz-based antiretroviral therapy.

BACKGROUND: There are few data on the prevalence of gestational diabetes (GDM) in pregnant women living with HIV (WLHIV) in sub-Saharan Africa, particularly those using integrase strand transfer inhibitors such as dolutegravir (DTG). METHODS: We prospectively enrolled pregnant WLHIV and pregnant women without HIV ≥18 years old in Gaborone, Botswana, excluding those with pre-existing diabetes. We screened for GDM using a 75 g oral glucose tolerance test (OGTT) performed at 24-28 weeks' gestation or at the earliest prenatal visit for those presenting after 28 weeks. Logistic regression models were fitted to assess the association between maternal HIV infection and GDM. Subgroup analyses were performed among WLHIV to assess the association between maternal antiretroviral therapy (ART) in pregnancy [DTG vs. efavirenz (EFV) with tenofovir/emtricitabine] and GDM. RESULTS: Of 486 pregnant women, 66.5% were WLHIV, and they were older than women without HIV (median age 30 vs. 25 years, P < 0.01). Among WLHIV, 97.8% had an HIV-1 RNA level < 400 copies/mL at enrolment. Overall, 8.4% had GDM with similar rates between WLHIV and those without HIV (9.0% vs. 7.4%). The WLHIV receiving DTG-based ART had a 60% lower risk for GDM compared with those on EFV-based ART (adjusted odds ratio = 0.40, 95% CI: 0.18-0.92) after adjusting for confounders. CONCLUSIONS: Pregnant WLHIV on ART in Botswana were not at increased risk of GDM compared with women without HIV. Among WLHIV, the risk of GDM was lower with DTG- than with EFV-based ART. Further studies with larger cohorts are warranted to confirm these findings.

Improvement in lipids after switch to boosted atazanavir or darunavir in children/adolescents with perinatally acquired HIV on older protease inhibitors: results from the Pediatric HIV/AIDS Cohort Study.

OBJECTIVES: Dyslipidaemia is common in perinatally HIV-infected (PHIV) youth receiving protease inhibitors (PIs). Few studies have evaluated longitudinal lipid changes in PHIV youth after switch to newer PIs. METHODS: We compared longitudinal changes in fasting lipids [total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and TC:HDL-C ratio] in PHIV youth enrolled in the Pediatric HIV/AIDS Cohort Study (PHACS) Adolescent Master Protocol (AMP) study who switched to atazanavir/ritonavir (ATV/r)- or darunavir/ritonavir (DRV/r)-based antiretroviral therapy (ART) from an older PI-based ART and those remaining on an older PI. Generalized estimating equation models were fitted to assess the association of a switch to ATV/r- or DRV/r-based ART with the rate of change in lipids, adjusted for potential confounders. RESULTS: From 2007 to 2014, 47 PHIV children/adolescents switched to ATV/r or DRV/r, while 120 remained on an older PI [primarily lopinavir/r (72%) and nelfinavir (24%)]. Baseline age ranged from 7 to 21 years. After adjustment for age, Tanner stage, race/ethnicity, and HIV RNA level, a switch to ATV/r or DRV/r was associated with a more rapid annual rate of decline in the ratio of TC:HDL-C. (ß = -0.12; P = 0.039) than remaining on an older PI. On average, TC declined by 4.57 mg/dL/year (P = 0.057) more in the switch group. A switch to ATV/r or DRV/r was not associated with the rate of HDL-C, LDL-C, or TG change. CONCLUSIONS: A switch to ATV/r or DRV/r may result in more rapid reduction in TC and the TC:HDL-C ratio in PHIV youth, potentially impacting long-term cardiovascular disease risk.

Metabolic abnormalities and viral replication are associated with biomarkers of vascular dysfunction in HIV-infected children.

OBJECTIVES: HIV-infected children may be at risk for premature cardiovascular disease. We compared levels of biomarkers of vascular dysfunction in HIV-infected children (with and without hyperlipidaemia) with those in HIV-exposed, uninfected (HEU) children enrolled in the Pediatric HIV/AIDS Cohort Study (PHACS), and determined factors associated with these biomarkers. METHODS: A prospective cohort study was carried out. Biomarkers of inflammation [C-reactive protein (CRP), interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP1)], coagulant dysfunction (fibrinogen and P-selectin), endothelial dysfunction [soluble intracellular cell adhesion molecule-1 (sICAM), soluble vascular cell adhesion molecule-1 (sVCAM) and E-selectin], and metabolic dysfunction (adiponectin) were measured in 226 HIV-infected and 140 HEU children. Anthropometry, body composition, lipids, glucose, insulin, HIV disease severity, and antiretroviral therapy were recorded. RESULTS: The median ages of the children were 12.3 years in the HIV-infected group and 10.1 years in the HEU group. Body mass index (BMI) z-scores, waist and hip circumferences, and percentage body fat were lower in the HIV-infected children. Total and non-high-density lipoprotein (HDL) cholesterol and triglycerides were higher in HIV-infected children. HIV-infected children also had higher MCP-1, fibrinogen, sICAM and sVCAM levels. In multivariable analyses in the HIV-infected children alone, BMI z-score was associated with higher CRP and fibrinogen, but lower MCP-1 and sVCAM. Unfavourable lipid profiles were positively associated with IL-6, MCP-1, fibrinogen, and P- and E-selectin, whereas increased HIV viral load was associated with markers of inflammation (MCP-1 and CRP) and endothelial dysfunction (sICAM and sVCAM). CONCLUSIONS: HIV-infected children have higher levels of biomarkers of vascular dysfunction than do HEU children. Risk factors associated with higher biomarkers include unfavourable lipid levels and active HIV replication.

Plasma C-type natriuretic peptide forms and thyroid status in prepubertal children with acquired thyroid disease.

OBJECTIVE: C-type natriuretic peptide (CNP) and thyroid hormone (TH) are essential for normal skeletal growth. Plasma CNP peptides correlate with growth velocity, but the relationship between thyroid status and CNP production is unknown. This study examined the impact of restoring normal TH levels on CNP and height velocity (HV) in children with acquired hypo- and hyperthyroidism. DESIGN: We performed a prospective, observational study in prepubertal children with acquired hypothyroidism (n = 15) and hyperthyroidism (n = 12). MEASUREMENTS: Blood levels of CNP, amino-terminal proCNP (NTproCNP), bone-specific alkaline phosphatase (BSAP), IGF-I and TH levels were measured before and during the first 6 months of standard treatment for hypo- and hyperthyroidism, and correlations were determined. RESULTS: At baseline, HV, CNP, NTproCNP and BSAP were significantly higher in hyper- than in hypothyroid subjects. Changes in TH after treatment were closely coupled to change in CNP and NTproCNP in hyperthyroid, but not in hypothyroid, children. In addition, a positive association of HV with CNP peptides was found during treatment of hyperthyroidism. Normalizing TH did not correlate with changes in BSAP or IGF-I in either group. CONCLUSIONS: Plasma CNP peptides are higher in children with hyperthyroidism than in those with hypothyroidism at diagnosis and, in hyperthyroid children, change concordantly with TH and HV during treatment. Differential responses of CNP in the two groups suggest CNP production is dependent on growth plate activity and not a direct effect of TH on CNP gene expression. Our findings suggest novel mechanisms underlying changes in skeletal response during treatment in children with acquired thyroid disease.

An arginine to histidine mutation in codon 311 of the C-erbA beta gene results in a mutant thyroid hormone receptor that does not mediate a dominant negative phenotype.

We have examined the c-erbA beta thyroid hormone receptor gene in a kindred, G.H., with a member, patient G.H., who had a severe form of selective pituitary resistance to thyroid hormones (PRTH). This patient manifested inappropriately normal thyrotropin-stimulating hormone, markedly elevated serum free thyroxine (T4) and total triiodothyronine (T3), and clinical hyperthyroidism. The complete c-erbA beta 1 coding sequence was examined by a combination of genomic and cDNA cloning for patient G.H. and her unaffected father. A single mutation, a guanine to adenine transition at nucleotide 1,232, was found in one allele of both these members, altering codon 311 from arginine to histidine. In addition, a half-sister of patient G.H. also harbored this mutant allele and, like the father, was clinically normal. The G.H. receptor, synthesized with reticulocyte lysate, had significantly defective T3-binding activity with a Ka of approximately 5 x 10(8) M-1. RNA phenotyping using leukocytes and fibroblasts demonstrated an equal level of expression of wild-type and mutant alleles in patient G.H. and her unaffected father. Finally, the G.H. receptor had no detectable dominant negative activity in a transfection assay. Thus, in contrast to the many other beta-receptor mutants responsible for the generalized form of thyroid hormone resistance, the G.H. receptor appeared unable to antagonize normal receptor function. These results suggest that the arginine at codon 311 in c-erbA beta is crucial for the structural integrity required for dominant negative function. The ARG-311-HIS mutation may contribute to PRTH in patient G.H. by inactivating a beta-receptor allele, but it cannot be the sole cause of the disease.

Effects of exenatide on weight and appetite in overweight adolescents and young adults with Prader-Willi syndrome.

BACKGROUND: Prader-Willi syndrome (PWS) is associated with hyperphagia and hyperghrelinemia with major morbidity because of obesity without effective medical treatment targeting hyperphagia. Exenatide (Byetta [synthetic Exendin-4]; AstraZeneca, Wilmington DE) is a GLP-1 receptor agonist which reduces appetite and weight and may be an effective treatment in PWS. OBJECTIVE: The objective of this study is to determine the effect of a 6-month trial of exenatide on appetite, weight and gut hormones in youth with PWS. METHODS: Ten overweight and obese subjects with PWS (13-25 years) were recruited for a 6-month open-label, non-randomized, longitudinal study conducted at Children's Hospital Los Angeles. Exenatide was given using standard diabetes dosing without dietary modifications. Weight, body mass index (BMI), truncal fat, appetite and plasma acylated ghrelin were measured over 6 months. Mixed meal tolerance tests were performed at 0 and 6 months. RESULTS: Appetite scores significantly decreased from baseline (32.2 ± 8.7) after 1, 3 and 6 moths of treatment (27.5 ± 8.8, 25.4 ± 9.3, and 25.4 ± 7.2 respectively; p = 0.004). Hemoglobin A1c decreased significantly after treatment, but weight, BMI z-score and adiposity did not. There was no significant change in ghrelin. CONCLUSIONS: This is the first longitudinal investigation of the effects of exenatide in subjects with PWS. It was effective in decreasing appetite, without change in weight or BMI in the short term. Larger, controlled, longer-term trials in patients with PWS are needed to confirm the efficacy and safety of exenatide and to evaluate whether its use might induce weight loss when given in conjunction with behavioural modification.

Primary Care Provider Management of Congenital Hypothyroidism Identified Through Newborn Screening.

OBJECTIVE: To assess Primary Congenital Hypothyroidism (CH) management patterns and feasibility of providing long-term care for patients with CH identified through newborn screening by Primary Care Providers (PCPs) in California and Hawaii. STUDY DESIGN: A survey was mailed to all physicians (N=823) listed as the referral doctor for confirmed patients with CH identified through newborn screening programs in both states between 01/01/2009-12/31/2013. Information was collected on CH management patterns, barriers to providing care, and knowledge on CH treatment. Descriptive statistics and bivariate logistic regression results were reported. RESULTS: 206 PCPs completed the survey. Among these, 78% currently have patients with CH and 91% indicated willingness to provide long-term care to new patients with CH. Among PCPs currently caring for patients with CH, 17% managed CH by themselves with limited assistance from endocrinologists; 63% were involved in managing CH but endocrinologists played a larger role than PCPs; 19% were not involved in CH care. Only 49% of PCPs correctly answered questions regarding recommended follow-up frequencies and 23% knew the correct age for a trial off levothyroxine for suspected transient CH. Top two perceived barriers to providing long-term care included "need guidance or support from endocrinologists" (61%) and "not familiar with CH treatment guidelines" (28%). CONCLUSION: The majority of PCPs surveyed are willing to provide long-term care to patients with CH, but need support from endocrinologists and increased knowledge about current treatment guidelines.

Growth hormone induces resistance to the mitogenic action of insulin through local IGF-I. Studies in normal and Pygmy T-cell lines.

Growth hormone (GH) and insulin have both mitogenic and metabolic actions. The growth-promoting effects of GH in vivo are thought to be mediated by insulin-like growth factor-I (IGF-I), whereas the metabolic effects of GH are thought to be either direct or mediated by factors other than IGF-I. In previous studies using HTLV-II-transformed T-lymphoblast cell lines established from normal individuals, we have shown that GH preincubation induces resistance to the growth-promoting (mitogenic) action of insulin. In this study, using T-cell lines from 3 American control subjects, 1 African control subject, and 1 African Pygmy (the latter previously shown to be resistant to the growth-promoting actions of both IGF-I and GH), we examined the role of local IGF-I in the mediation of GH-induced resistance to the mitogenic action of insulin. In these studies, we quantified the stimulation of T-cell colony formation in response to insulin in the presence and absence of either GH or IGF-I.(ABSTRACT TRUNCATED AT 250 WORDS)

Use of in vitro clonogenic assays to differentiate acquired from genetic causes of insulin resistance.

Insulin resistance may be due directly to genetically programmed disorders of insulin action or acquired defects in which environmental factors influence insulin action. To address the issue of this distinction, we studied the ability of insulin to stimulate colony formation in primary cultures of erythroid progenitors (assumed to retain environmental influences) and immortalized T lymphocytes (presumed to reflect only genetic influences). Four patients with hyperinsulinemia and disturbed glucose metabolism were studied (2 patients with acanthosis nigricans, 1 of whom had circulating anti-insulin-receptor antibodies, 1 with partial lipodystrophy, and 1 with Cushing's syndrome). The mean colony-forming ability of their erythroid progenitor cells in response to insulin stimulation (less than or equal to 1.6 pM) was significantly blunted compared with control cells (P less than 0.05). The mean responsiveness of their immortalized T-lymphoblast cell lines to similar insulin concentrations was no different than that of control T-lymphocyte lines, consistent with an acquired cause for the observed insulin resistance in each case. A T-lymphocyte line from a patient with leprechaunism, however, showed no stimulation in response to physiological concentrations of insulin. With these same in vitro methodologies, there was normal T-lymphocyte line responsiveness to insulinlike growth factor I (IGF-I) or insulin concentrations greater than 8.6 pM; both of these responses could be completely blocked by preincubation with an antibody to the IGF-I receptor. These findings suggest that, despite resistance to physiological levels of insulin, the high circulating insulin concentrations present in the serum of these patients could mediate unwanted tissue-specific growth through an intact IGF-I receptor-effector mechanism.

Dominant and nondominant negative C-erbA beta 1 receptors associated with thyroid hormone resistance syndromes augment 12-O-tetradecanoyl-phorbol-13-acetate induction of the collagenase promoter and exhibit defective 3,5,3'-triiodothyronine-mediated repression.

C-erbA receptors and v-erbA have been shown to functionally interact with 12-O-tetradecanoyl-phorbol-13-acetate (TPA)-inducible gene expression. These proteins enhance trans-activation by c-jun, and the c-erbA receptors in the presence of thyroid hormone repress TPA and c-jun induction of transcription. Also, v-erbA can abrogate T3-mediated repression. We have examined how dominant negative (S and CL) and nondominant negative (G-H) receptors cloned from various patients with thyroid hormone resistance syndromes affect expression of the collagenase promoter induced with TPA. The CL receptor (ARG315HIS mutation) has a 2-fold reduction in T3-binding affinity compared with human c-erbA beta 1 wild-type (WT) receptor, whereas the G-H receptor (ARG311HIS) and S receptor (deletion, THR codon 332) have T3-binding affinities reduced by 100-fold and greater than 100-fold, respectively. These mutant receptors were cotransfected with a collagenase promoter (-1200 to +63 base pairs) chloramphenicol acetyltransferase reporter gene (Col-CAT) into COS-7 cells. Levels of CAT reporter gene expression after transient transfection were determined in the presence or absence of 3-10 nM T3 and the presence or absence of 100 nM TPA. Unoccupied CL receptor and G-H and S receptors stimulated TPA-induced Col-CAT expression 1.5- to 9-fold. The CL receptor with thyroid hormone totally repressed TPA induction of the collagenase receptor. In the presence of thyroid hormone, the enhancing effects by S and G-H receptors on TPA-induced Col-CAT expression were unaffected and minimally diminished, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Divergent dimerization properties of mutant beta 1 thyroid hormone receptors are associated with different dominant negative activities.

Syndromes of resistance to thyroid hormones are caused by mutations in the T3-binding domain of the c-erbA beta thyroid hormone receptor gene. The S receptor (deletion of THR332) is a potent dominant negative protein cloned from a kindred with generalized resistance to thyroid hormones. The G-H receptor (ARG311HIS) has compromised dominant negative function and was found in both normal individuals and in a patient with severe pituitary resistance to thyroid hormones. We have investigated the mechanism responsible for the difference in receptor phenotypes by analyzing the binding of S and G-H receptors to thyroid hormone response elements with electrophoretic mobility shift analysis. Wild-type human c-erbA beta 1 (WT), S, and G-H receptors were synthesized in reticulocyte lysate, reacted with a thyroid hormone response element consisting of a direct repeat with 4 base pairs (DR+4; AGGTCA CAGG AGGTCA), and the products analyzed by gel shift. G-H receptor homodimerization was greatly impaired; G-H formed predominantly monomeric complex compared with monomeric and homodimeric WT complexes. The G-H receptor was able to form heterodimeric complexes with cellular thyroid hormone receptor auxiliary protein (TRAP) factors including the human retinoid X receptor-alpha. When TRAP was limiting, the levels of G-H heterodimeric complex were 2- to 3-fold reduced compared with WT receptor. In contrast to the WT and G-H receptors, the S receptor formed almost exclusively homodimeric complex with DR+4; the approximate ratio of S:WT:G-H homodimeric complexes at equivalent concentrations of receptors was 60:20:1. A measurable increase (1.2- to 2.6-fold) in heterodimeric complex formation was observed with the S receptor relative to WT when TRAP was at limiting concentration. As reported previously by others, thyroid hormone significantly reduced the WT homodimeric complex with DR+4. There was no effect on the S homodimeric complex. Finally, the WT, S, and G-H receptors formed different complexes with the element consisting of an inverted repeat with 5 base pairs (IR+5; AGGTCA ACAGT TGACCT) and the IR element (AGGTCA TGACCT), which were differently regulated by thyroid hormone. The S receptor bound as a homodimer with IR+5, whereas the WT receptor bound as a homodimer only with thyroid hormone. No homodimeric complex formed with IR+5 and the G-H receptor. Qualitatively similar results were observed with the IR element. We conclude that the ARG311HIS mutation severely perturbs the homodimerization and, to a much less degree, heterodimerization functions of the c-erbA beta 1 receptor. Furthermore, the THR332 deletion mutation augments homodimerization of the c-erbA beta 1 receptor. These results indicate that different mutations in the c-erbA beta 1 thyroid hormone receptor have divergently affected dimerization activities which seem to influence the level of dominant negative activity in man.

Selective insulin action on skin, ovary, and heart in insulin-resistant states.

States of hyperinsulinemia with resistance to insulin action on glucose disposal are frequently associated with proliferative tissue abnormalities of the skin (acanthosis nigricans), ovary, and heart. That insulin may be involved in the pathogenesis of these growth-related abnormalities despite resistance to its metabolic effects mediated through the insulin receptor is suggested by the known ability of high concentrations of insulin to stimulate DNA synthesis and cell proliferation in vitro through the insulin-like growth factor I (IGF-I) receptor. IGF-I receptors are present in skin keratinocytes, some ovarian tissue compartments, and in the heart. Furthermore, ovarian tissue from hyperinsulinemic insulin-resistant women responds to supraphysiologic insulin concentrations in vitro by enhanced steroidogenesis. Cultured, transformed T-lymphocytes from an infant with leprechaunism fail to augment basal-colony formation in response to physiologic insulin concentrations in vitro (compared to a doubling seen in normal subjects), but respond normally to supraphysiologic insulin concentrations, the effect of which is competitively inhibited by a monoclonal antibody to the IGF-I receptor. Thus, insulin action mediated through the IGF-I receptor may initiate growth-promoting tissue effects in the face of limited insulin effect on glucose metabolism. Such spillover actions may add to the morbidity associated with states of clinical insulin resistance.

Early-morning hyperglycemia in diabetic individuals treated with continuous subcutaneous insulin infusion.

Significantly early-morning hyperglycemia was observed in insulin-dependent diabetic individuals who were otherwise well controlled while receiving a continuous subcutaneous insulin infusion (CSII) at standard doses. We measured the levels of the five key counterregulatory hormones (CRH) throughout the night for a total of 10 patient-nights in four such patients. No abnormalities in the patterns of glucagon, cortisol, growth hormone, epinephrine, or norepinephrine secretion were observed. Stepping up the daytime basal infusion rate in six affected patients before bedtime by 37.0 +/- 7.5% and maintaining the increased infusion until breakfast significantly blunted this early-morning hyperglycemia without causing significant early nighttime hypoglycemia. Plasma glucose concentrations before breakfast averaged 106.8 +/- 13.0 mg/dl after increase of the overnight basal infusion rate as compared with 269.8 +/- 39.1 mg/dl while receiving a single basal rate over 24 h (P less than 0.02). Thus, the "dawn phenomenon" may occur in patients receiving CSII by an unmodified algorithm and may be obviated by a carefully determined step-up in nocturnal basal infusion rate. The mechanism responsible for this phenomenon of increased early-morning insulin need remains to be elucidate.

Permanent diabetes without serological evidence of autoimmunity after transient neonatal diabetes.

OBJECTIVE: To describe a probable association between TNDM and subsequent permanent IDDM. RESEARCH DESIGN AND METHODS: A longitudinal follow-up of a single case from birth to 12 yr of age was conducted analyzing sequential OGTTs, ICAs, AIAs, anti-GAD antibodies, and other organ-specific and nonspecific antibodies. RESULTS: A small-for-gestational-age infant developed hyperglycemia at 20 h of age and required insulin therapy for the 1st 14 wk of life (TNDM). Transient hyperglycemia and ketonuria were noted again at age 2 yr 10 mo during an intercurrent illness, but OGTT was normal; and ICA, AIA, anti-GAD65 and anti-GAD67 antibodies, antithyroid microsomal, anti-gastric parietal cell, antiadrenal, antisteroidal, and antinuclear antibodies were negative 3 wk later. At age 9 yr, hyperglycemia returned and persisted in the setting of hypoinsulinemia; ICA, AIA, anti-GAD65 and anti-GAD67 antibodies, and other organ-specific and nonspecific antibodies were again negative. Insulin therapy was initiated and has been maintained over 3 yr of follow-up. CONCLUSIONS: Our case is the fifth reported with permanent diabetes occurring after resolution of TNDM. The etiology of permanent diabetes in this setting is unknown but, unlike classical IDDM, appears unrelated to autoimmunity in our patient. The true frequency of this association remains unknown.

Growth hormone induces insulin resistance in Laron dwarf cells via lactogenic receptors.

GH is the hormone primarily responsible for regulating body size within the genetic program. While GH has pleiotropic actions on cellular growth and metabolism, most of its effects are believed to be mediated by a single GH receptor. This receptor is not functional in tissues from patients with Laron dwarfism. We used human T-cell leukemia virus-immortalized T-lymphoblast cell lines from Laron dwarfs and normal individuals to examine the mechanism of GH-induced insulin resistance at the cellular level. GH (5-500 micrograms/L) caused a profound decrease in the sensitivity of normal T-lymphoblasts in response to all insulin concentrations (P < 0.0001 vs. insulin alone); pretreatment with GH and GH receptor antibody significantly improved sensitivity to all concentrations of insulin (P = NS vs. insulin alone). Preincubation with GH and PRL receptor antibody was associated with partial improvement in insulin sensitivity (P = 0.004 vs. insulin alone). Thus, in normal T-cell lines, the major pathway of GH-induced insulin resistance appears to be directed by the GH receptor, with a smaller effect mediated through the PRL receptor. While T-cell lines from Laron dwarfs do not respond to GH in clonal proliferation assays, GH (50 and 100 micrograms/L) caused profound insulin resistance in these cells (P = 0.008 and P < 0.0001, respectively, vs. insulin alone). GH receptor antibody did not abrogate this effect at any insulin concentration (P = NS vs. insulin alone), but there was partial restoration of insulin sensitivity when GH and PRL receptor antibody were coincubated (P = 0.0069 vs. insulin alone). Thus, in Laron T-cell lines, PRL and perhaps other lactogenic receptors appear to mediate GH-induced insulin resistance. The kinetics of GH-induced insulin resistance in Laron T-cells were also distinct from the pattern seen in normal T-cells, and unlike in normal cells, GH had no effect on insulin-like growth factor-I-induced clonal expansion of Laron T-cell lines (P = NS vs. insulin-like growth factor-I alone). These results provide evidence for an alternative pathway of GH action revealed in cells lacking classical growth responses to GH.

Insulin-like growth factor I resistance in immortalized T cell lines from African Efe Pygmies.

Previous investigations suggested that resistance to GH was the cause of short stature of African Pygmies. Because many of the actions of GH are mediated by insulin-like growth factor I (IGF-I), we sought to determine whether Pygmy tissue was responsive to IGF-I. An initial effort to obtain HTLV-II-transformed T lymphoblast cell lines resulted in a single cell line that showed complete resistance to both IGF-I and GH in a clonal proliferation assay as well as decreased IGF-I binding. In the current study, we examined T cell lines from seven Efe Pygmy subjects, three neighboring Lese farmers, and six American controls and quantified clonal responses to IGF-I, GH, and insulin. The T cell lines from the Efe Pygmies were all completely resistant to the growth-promoting actions of IGF-I concentrations less than 250 micrograms/L and GH concentrations less than 500 micrograms/L. The Lese population, with whom there is admixture with the Efe population, showed heights and clonal responses to IGF-I and GH intermediate between those of Pygmies and American controls. The Pygmy T cell lines showed reduced clonal proliferation in response to high insulin concentrations known to act through the IGF-I receptor. These findings indicate that genetic IGF-I resistance is present in the T cell lines of Efe Pygmies and suggest that unresponsiveness to IGF-I may be responsible for their short stature.

T-lymphoblast cell lines from Laron dwarfs augment basal colony formation in response to extremely high concentrations of growth hormone.

The clinical entity of Laron dwarfism is characterized by resistance to both endogenous and exogenous GH and may be due to a deficiency or absence of functional GH receptors. We previously showed that two types of hematopoietic cells derived from these patients are resistant to the in vitro growth-promoting action of GH at concentrations below 500 micrograms/L. In the current study we found that Laron T-cell lines had a mean peak augmentation of basal colony formation of 22 +/- 3.4% above baseline in response to a GH concentration of 10,000 micrograms/L. Since cloned cDNAs for human and rabbit GH receptors and rat PRL receptors show a high degree of sequence homology, we undertook studies of PRL action in cells from patients with Laron dwarfism to determine if the Laron defect was also associated with PRL unresponsiveness. Quantitating the augmentation of colony formation by T-lymphoblast cell lines established from three Laron dwarfs, we found normal responsiveness to PRL at concentrations of 25-10,000 micrograms/L. It is, thus, possible that the responsiveness of Laron T-cell lines to very high concentrations of GH could be mediated through an intact PRL (or other lactogenic) receptor based on the known affinity of GH for these receptors in other systems. These data suggest that cells from patients with Laron dwarfism have normal in vitro responsiveness to PRL and that the defect in Laron dwarfism appears to be specific to the GH receptor-effector pathway. It remains to be determined whether intact alternative lactogenic receptor mechanisms subserve any clinical effects of GH in patients with Laron dwarfism.

Bromocriptine and Triac therapy for hyperthyroidism due to pituitary resistance to thyroid hormone.

Although a number of patients with generalized resistance to thyroid hormone have been treated with bromocriptine (Brc), only one previously reported patient with nontumoral TSH-mediated hyperthyroidism, presumably due to pituitary resistance to thyroid hormone (PRTH), has been successfully treated with bromocriptine (Brc). In addition, several studies suggested that the T3 analog 3,5,3'-triiodothyroacetic acid (Triac) may control hyperthyroidism in patients with PRTH. In the current study a patient with PRTH diagnosed at age 15 yr underwent separate therapeutic trials with Brc and Triac, during which time physical parameters, thyroid function tests, systolic time intervals (STI), and oxygen consumption (VO2) were measured. On Brc therapy (12.5 mg/day), heart rate decreased (108 to 72/min), TSH decreased (5.7 to 1.2 mU/L), T3 decreased (9.9 to 1.7 nmol/L), free T4 decreased (205 to 21 pmol/L), STI lengthened (left ventricular ejection time, 0.389 to 0.405 s), and VO2 did not change (164 to 162 mL/min). We found no significant clinical improvement with a maximal dose of Triac (2.1 mg/day), only minimal reduction in goiter size; mild decreases in T3 (9.9 to 6.7 nmol/L), free T4 (205 to 113 pmol/L), and TSH (5.7 to 5.4 mU/L); no change in STI (left ventricular ejection time, 0.389 to 0.401 sec); and an increase in O2 consumption (VO2, 164 to 209 mL/min). Thus, the results favor Brc as effective therapy for this patient with PRTH.

The use of theophylline as an in vivo probe of adrenocortical function.

The first step in the stimulatory action of most polypeptide hormones, including ACTH, is interaction with a specific target organ plasma membrane receptor. Theophylline, a nonspecific stimulus of several endocrine processes, does so presumably by circumventing the receptor step and directly increasing cAMP by inhibiting phosphodiesterase-mediated hydrolysis. Five patients with adrenal insufficiency, documented by a lack of cortisol secretion in response to exogenous ACTH, underwent a 4-h iv infusion of theophylline. In three of the five individuals, a significant concentration of cortisol was measured in serum for the first time. The patients who responded included one patient with the syndrome of ACTH insensitivity, one with ACTH deficiency, and one with idiopathic primary adrenal failure. Two patients with autoimmune adrenalitis failed to respond to theophylline, although one was tested very early in the course of her disease. We also noted that theophylline stimulated renin secretion and, in one patient with an intact zona glomerulosa, evoked a secondary rise in aldosterone equal to that produced by diuresis and upright posture. These studies suggest that the preservation of cortisol responsiveness to theophylline, after the loss of sensitivity to ACTH, may be relate to either the duration of the adrenal insufficiency or to the etiological mechanism. Patients with autoimmune adrenalitis may undergo more rapid and complete adrenocortical destruction, therapy losing sensitivity to both ACTH and theophylline, whereas patients with insufficient or ineffective ACTH stimulation may have receptor failure before the loss of intracellular function. Thus, responsiveness to iv theophylline may serve not only as a probe of potential adrenocortical reserve, but also as an indicator of pathogenesis.

Absence of nonclassical congenital adrenal hyperplasia in patients with precocious adrenarche.

We studied 31 patients (28 girls and 3 boys), ranging in age from 3.2-7.9 yr, with precocious adrenarche defined by the presence of early sexual hair development, no signs of virilization, and bone age within +3 SD of the mean for chronological age. To determine if this symptom complex stemmed from any form of nonclassical (late-onset) congenital adrenal hyperplasia, an ACTH stimulation test was performed on each patient using a standard 0.25-mg dose of Cortrosyn, given as an iv bolus. Twelve pubertal children (7 girls and 5 boys) and 18 prepubertal children (11 girls and 7 boys) served as normal controls. Baseline and stimulated 17-hydroxypregnenolone (17-OHPreg), 17-hydroxyprogesterone, (17-OHP), 11-deoxycortisol, dehydroepiandrosterone, androstenedione, testosterone, and cortisol levels were measured. Using published nomogram standards for serum 17-OHP response to ACTH, no child with precocious adrenarche was diagnosed as having nonclassical 21-hydroxylase deficiency. Eight girls, however, had a stimulated 17-OHP value that exceeded the mean response for pubertal and prepubertal controls by more than +2 SD [range, 295-670 ng/dL (8.94-20.3 nmol/L)]. Stimulated 11-deoxycortisol values [less than 400 ng/dL (11.6 nmol/L)] ruled out any cases of nonclassical 11 beta-hydroxylase deficiency. No patient had nonclassical 3 beta-hydroxysteroid dehydrogenase deficiency, as defined by both the stimulated 17-OHPreg and the 17-OHPreg/17-OHP ratio to be more than +2 SD above the mean for pubertal children [1354 ng/dL (41.0 nmol/L) and 10.4, respectively]. In conclusion, we could not provide any biochemical evidence for nonclassical congenital adrenal hyperplasia in a large group of children with precocious adrenarche.