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. (β = -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.

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.

A four-year, open-label, multi-center, randomized, two-arm study of Genotropin® in patients with idiopathic short stature: comparison of an individualized, target-driven treatment regimen to standard dosing of Genotropin® - analysis of two-year data

BACKGROUND

Several models have been developed to predict growth response to growth hormone (GH) based on auxological and biochemical parameters for children with non-GH-deficient, idiopathic short stature (ISS).

OBJECTIVE

To demonstrate if an individualized, formula-based, target-driven GH regimen for children with ISS would lead to a height (Ht) gain to -1.3 SDS during the first 24 months of treatment of this 4-year study, with less variability than with standard weight-based dosing.

METHODS

A 4-year, open-label, multi-center, randomized, two-arm study comparing formula-based dosing of Genotropin® GH from 0.18 to 0.7 mg/kg/week versus standard FDA-approved ISS dosing of Genotropin® (0.37 mg/kg/week). Subjects (n = 316, 89 females) were prepubertal, 3-14 years of age, bone age 3-10 years (m) and 3-9 years (f), naive to GH treatment, Ht SDS -3 to -2.25, Ht velocity <25th percentile for bone age, and peak GH >10 ng/ml.

RESULTS

The majority (83%) of subjects had Ht SDS within the normal range by 2 years. All subjects displayed catch-up growth consistent with other studies of GH treatment of ISS.

CONCLUSION

The formula-based therapy did not meet the primary endpoint achieving targeted gain with lower variability. No new safety concerns were found.

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.

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.

Effect of protease inhibitors combined with standard antiretroviral therapy on linear growth and weight gain in human immunodeficiency virus type 1-infected children

Children with HIV-1 infection and poor growth have a significant increase in the risk of death. We studied the effects of protease inhibitors on the height and weight of 27 HIV-1-infected children and found that in our small pilot study, protease inhibitor therapy had a positive effect on the heights of HIV-1-infected children. Accelerated height velocity was sustained for at least 18 to 20 months.

Trans-sphenoidal and sphenoethmoidal encephalocele: report of two cases and review of the literature

Basal encephaloceles are the least common form of encephalocele. Due to the critical position of the bony defect, visual and endocrinological abnormalities are frequently associated with basal encephaloceles. There is significant confusion in the classification of basal encephaloceles, particularly among trans-sphenoidal, sphenoethmoidal and intrasphenoidal subtypes. Two cases of basal encephaloceles are presented (one trans-sphenoidal and one sphenoethmoidal), along with a review of the literature. The relationship between the basal encephaloceles and endocrinological abnormalities is also emphasized.

Near-normal linear growth in the setting of markedly reduced growth hormone and IGF-1. A case report

A 14.2-year-old prepubertal boy diagnosed with complete-type growth hormone deficiency and tertiary hypothyroidism, keeps growing in the height range between -1 and -2 SD. He has been treated with levothyroxine only. To understand the growth mechanism of this boy, we analyzed the serum growth hormone (GH) with a radioimmunoassay (RIA), serum GH bioactivity with Nb2 and erythroid progenitor cell bioassays, and growth hormone-binding protein (GHBP) with a ligand-mediated immunofunctional assay (LIFA). In addition, IGF-1 and free IGF-1 were analyzed by immunoradiometric assay (IRMA) and insulin-like growth factor-binding protein-3 (IGFBP-3) by Western immunoblot. Peak GH-RIA responses to insulin, arginine and GH-releasing factor, and nocturnal GH secretion, were low (0.5-2.3 ng/ml); bioactive GH was low (0.313 ng/ml), and GHBP was elevated (84 ng/ml). The serum levels of IGF-1 and free IGF-1 were continuously low, 17.1-39.3 and 0.17-0.26 ng/ml, respectively. Moreover, serum IGFBP-3 levels were low (1.68- 1.39 mg/l) and IGFBP-3 protease activity was negative. Prolactin and insulin were in the normal range. The result of the assay for growth-promoting activity showed that the patient's serum stimulated normal erythroid progenitor cells twice as potently as did healthy thin adult control serum. These results suggest that GH and IGF-1 are not indispensable for maintaining physical growth in this boy. Thus, it appears that circulating GH and IGF-1 are not mandatory requirements for maintaining normal physical growth, and other, as yet uncharacterized, pathways or growth factors might be sufficiently compensatory under certain conditions.

Aplasia of right internal carotid artery and hypopituitarism

BACKGROUND

The pathogenesis of congenital hypopituitarism is unknown in many cases.

OBJECTIVE

We report a case of congenital pan-anterior hypopituitarism in association with a complex vascular abnormality involving the central nervous system, nasal pyriform aperture stenosis, and a single central maxillary incisor.

MATERIALS AND METHODS

MRI and MRA were used to define this patient's complex vascular anomaly.

RESULTS

The vascular abnormality consists of absence of the right common carotid artery, the right internal carotid artery, the A1 segment of the right anterior cerebral artery, the anterior communicating artery, and partial absence of the M1 segment of the right middle cerebral artery.

CONCLUSION

This unusual vascular anomaly may contribute to the pathogenesis of some cases of congenital hypopituitarism and related midline abnormalities, or may result from a common defect that causes pituitary insufficiency.

Four contiguous amino acid substitutions, identified in patients with Laron syndrome, differently affect the binding affinity and intracellular trafficking of the growth hormone receptor

We have analyzed the GH receptor (GHR) gene in four individuals with Laron syndrome, and a missense mutation was identified for each patient in the extracellular domain of the GHR (D152H, I153T, Q154P, and V155G). The D152H mutation was previously reported. We have reproduced the three novel mutations in the GHR complementary DNA and analyzed their consequences in human 293 transfected cells. In cells expressing the I153T and V155G mutants, binding of [125I]human GH at the cell surface was very low, whereas binding to total membrane fractions was much less affected, suggesting impaired cell surface expression. Binding assays with cells expressing the Q154P mutant revealed severe defects both at the cell surface and in total particulate membrane fractions. Immunofluorescence experiments confirmed that cell surface expression of the three mutants was altered, and colocalization studies suggested that most of the mutant receptors are retained in the endoplasmic reticulum. Endoglycosidase H resistance tests also indicated that the majority of I153T and V155G GHRs are trapped in the endoplasmic reticulum. Thus, mutations on contiguous amino acids of the GHR result in various defects. The I153T, Q154P, and V155G mutations mainly affect intracellular trafficking and binding affinity of the receptor, whereas the D152H mutation affects receptor expression, dimerization, and signaling.

Minipuberty of infancy and adolescent pubertal function in adrenal hypoplasia congenita

An infant and his uncle, both with adrenal hypoplasia congenita, shared the same DAX1 mutation. The adolescent uncle had hypogonadotropic hypogonadism, but the infant had a normal minipuberty of infancy. These observations suggest differences in the physiologic mechanisms regulating the hypothalamic-pituitary-gonadal axis in infancy and adolescence.

Normal growth in a patient with septo-optic dysplasia despite both growth hormone and IGF-I deficiency

A 17 year-old female with septo-optic dysplasia (SOD) and hypopituitarism who has grown normally despite GH deficiency is presented. Her serum was examined to test current hypotheses to explain the phenomenon of growth without GH. The patient's serum possessed potent in vitro growth-promoting activity (GPA) in an erythroid progenitor-cell clonal proliferation assay consistent with the patient's normal growth performance. In contrast to previously reported cases of growth without GH, total IGF-I concentrations were very low in this patient, precluding IGF-I being responsible for the observed GPA and normal growth pattern. Furthermore, circulating free IGF-I was also low which is reported for the first time in such a case. A detailed picture of IGF-binding proteins is also presented. To test the hypothesis that hyperinsulinemia might be responsible for the observed GPA, in vitro GPA experiments were performed before and after removal of insulin by immunodepletion. Neither partial nor complete removal of insulin abolished the in vitro cell proliferation response. These data demonstrate that neither IGF-I nor insulin is the factor responsible for GPA in at least this patient with SOD and growth without GH.

Impact of overnight dexamethasone suppression on the adrenal androgen response to an oral glucose tolerance test in women with and without polycystic ovary syndrome

In order to test the hypothesis that adrenocortical overactivity, possibly related to the stress of testing, may impact on the measurement of circulating androgen concentrations during glucose-induced hyperinsulinaemia, we prospectively screened 10 patients with the polycystic ovary syndrome (PCOS) and nine healthy control women with an oral glucose tolerance test (OGTT), before and after the administration of dexamethasone. Blood sampling was performed at 0, 30, 60, 90, and 120 min following the oral ingestion of 75 g of glucose, before and after the administration of 1.0 mg dexamethasone on the evening prior to testing. Total and free testosterone, androstenedione, dehydroepiandrosterone (DHEA), DHEA sulphate (DHEAS), cortisol, glucose and insulin were assessed during the 2 h OGTT. Women with PCOS had increased basal concentrations of free testosterone, total testosterone, androstenedione, and insulin compared to control women. In women with PCOS an acute decline in circulating concentrations of DHEAS occurred during the OGTT. In PCOS women there were no changes in other ovarian or adrenal androgens during OGTT before or following dexamethasone administration. In control women DHEA concentrations declined during the OGTT. Following overnight dexamethasone suppression in control women, circulating concentrations of DHEAS and testosterone also declined. It is concluded that: (i) in PCOS women only the concentration of circulating DHEAS decreased during glucose-induced hyperinsulinaemia and dexamethasone administration did not further alter androgen responses to an OGTT; (ii) it is possible that, in these hyperandrogenic patients, the insulin-related suppression of adrenocortical testosterone and DHEA is negated by their much greater ovarian secretion of these androgens; (iii) in control women DHEA concentrations acutely declined during the OGTT and the administration of dexamethasone resulted in the acute decline of DHEA, DHEAS, and testosterone; (iv) it appears that the stress related to testing impacts on the androgen response to OGTT, at least in healthy women.

IGF-I does not mediate T-lymphoblast colony formation in response to estradiol, testosterone, 1,25(OH)2 vitamin D3, and triiodothyronine: studies in control and pygmy T-cell lines

The mechanism by which estradiol, testosterone, 1,25(OH)2 vitamin D3, and triiodothyronine promote tissue growth is unknown, although, in some tissues, a role for local IGF-I has been suggested. We previously showed that HTLV-II-transformed T-cell lines from healthy adults augmented basal colony formation in response to peptide (growth hormone, parathormone, and adrenocorticotrophin) and glycoprotein (thyroid-stimulating hormone) hormones through stimulation of local IGF-I. T-cell lines from African Efe Pygmies, however, were resistant to the direct growth-promoting action of IGF-I, as well as to the growth-promoting action of growth hormone, parathormone, adrenocorticotrophin, and thyroid-stimulating hormone. We, therefore, used these cell lines to determine the mechanism of T-cell growth in response to steroid and thyroid hormones. We quantified colony formation of American control T-cell lines in the presence and absence of alpha IR-3 antibody against the type 1 IGF receptor and Pygmy T-cell lines in response to estradiol (36.7-1835 pmol/ liter), testosterone (34.7-17,350 pmol/liter), 1,25(OH)2 vitamin D3 (2.4-24,000 pmol/liter), and triiodothyronine (1536-192,000 pmol/liter). There were no statistically significant differences by ANOVA in overall response curves for any of the four hormones comparing control clonal responses in the presence or absence of alpha IR-3 and no statistically significant difference in overall responsiveness between control and Pygmy T-cell lines. From these data, we conclude that (i) normal T-cell lines grow in response to estradiol, testosterone, 1,25(OH)2 vitamin D3, and triiodothyronine; (ii) these responses are not mediated through local IGF-I since they are not blocked by pretreatment with antibody to the type 1 IGF receptor; and (iii) Pygmy T-cell lines, which are genetically resistant to IGF-I, grow equivalently to control T-cell lines in response to estradiol, testosterone, 1,25(OH)2 vitamin D3, and triiodothyronine, further underscoring the IGF-I independence of this stimulation in our system.

The growth without growth hormone syndrome

The phenomenon of growth without GH has been recognized for over a quarter of a century in various physiologic or near-physiologic situations, including the fetal state and obesity, and in various obviously pathologic states, including postsurgical resection of suprasellar/hypothalamic tumors, most notably craniopharyngiomas, and in acromegaloidism. The mechanism or mechanisms responsible for this fascinating clinical syndrome are unknown. The available data implicate, at least in some of these subjects, a role for hypothalamic injury leading to obesity and insulin resistance which, in turn, leads to elevated circulating concentrations of insulin to which the body retains mitogenic sensitivity. Alternatively, in other subjects with this syndrome, evidence exists to support the presence of a circulating as yet incompletely characterized potent growth-promoting factor which appears in the serum. Further studies of this syndrome should help to enhance our knowledge of the mechanisms governing both normal and abnormal human growth.

IGF-I resistance in virus-transformed B-lymphocytes from African Efe Pygmies

To investigate IGF-I resistance in African Efe Pygmies, we examined clonal responsiveness to IGF-I in Epstein-Barr virus-transformed B-lymphocytes from three Efe Pygmies and three American control subjects. The Efe B-lymphoblasts did not increase clonal responsiveness when incubated with IGF-I (as high as 250 micrograms/liter) in contrast to the control B-lymphoblasts which showed a bimodal dose-response with a maximal stimulation of 50% above baseline. The proliferative response of Efe B-lymphoblasts was similar to that of control B-lymphoblasts when incubated with another growth factor, phorbol 12-myristate 13-acetate, which does not activate the IGF-I receptor. These findings indicate that Efe Pygmy B-lymphoblasts are resistant to IGF-I as measured by in vitro clonal proliferation assays. Coupled with our previous report of IGF-I unresponsiveness in Efe Pygmy HTLV-II-transformed T-lymphocytes, these data suggest that IGF-I resistance is generalized and may play a central role in the etiology of short stature in this population.

Decreased insulin-like growth factor I receptor expression and function in immortalized African Pygmy T cells

Efe Pygmies of northeast Zaire have the shortest mean adult stature of any population on earth. Although various alterations in the GH/insulin-like growth factor I (IGF-I) axis have been suggested, the basis for short stature in the Pygmy is unknown. We previously described IGF-I unresponsiveness in a T lymphoblast cell line derived from an Efe Pygmy, and studies in five additional lines have confirmed severe IGF-I resistance in these cells. We have now performed experiments to determine the molecular basis for the IGF-I resistance in these cells. We found markedly decreased cell surface expression of IGF-I receptors with normal ligand binding affinity. The Pygmy IGF-I receptors were not autophosphorylated and did not transmit a signal in response to physiological concentrations of IGF-I. There was a substantially decreased level of IGF-I receptor messenger ribonucleic acid in the Pygmy cells with a normal messenger ribonucleic acid half-life. The nucleotide sequence of the full-length IGF receptor complementary DNA in Pygmy 1 showed no significant variation. These results indicate decreased IGF-I receptor gene transcription and IGF-I receptor signaling as the primary variation in the Pygmy cell lines. The findings point to the IGF-I receptor as the locus governing short stature in the African Pygmy and suggest that human stature may be genetically controlled by expression of the IGF-I receptor.

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.

Growth-promoting actions of parathyroid hormone, adrenocorticotrophic hormone, and thyroid-stimulating hormone: in vitro studies in normal and pygmy T-lymphoblast cell lines

We used an in vitro T-lymphoblast clonal proliferation assay to quantify human IGF-I (hIGF-I)-, human PTH (hPTH)-, human ACTH (hACTH)-, and human TSH (hTSH)-stimulated growth of human T-cell leukemia virus-II-transformed T-lymphoblast cell lines from normal individuals and to elucidate the role of IGF-I as the mediator of hPTH-, hACTH-, and hTSH-induced T-cell growth. Normal T-lymphoblast cell lines respond to hIGF-I in a bimodal fashion. The mean first peak response was 143 +/- 9.8% above baseline (defined as 100%) occurring at 8 micrograms/L, and the mean second peak response was 154 +/- 14.4% occurring at 100 micrograms/L. Both responses were completely blocked after incubation with alpha IR-3, an MAb to the IGF-I receptor (by analysis of variance, p = 0.015 between full response curves). After stimulation with hPTH, the mean peak clonal response of normal T-lymphoblast cell lines was 189 +/- 7.0%; after incubation with alpha IR-3, the mean peak clonal response was 108 +/- 7.9% (p = 0.0015 between full response curves). The mean peak clonal response of normal T-lymphoblast cell lines after hACTH stimulation was 192 +/- 8.6%; preincubation with alpha IR-3 reduced the mean peak clonal response to 94 +/- 1.2% (p < 0.0001 between full response curves). With hTSH stimulation, the mean peak clonal response of normal T-lymphoblast cell lines was 167 +/- 7.0%; after incubation with alpha IR-3, the mean peak clonal response was 94 +/- 8.2% (p = 0.003 between full response curves).(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of heterogeneous mutations causing constitutive activation of the luteinizing hormone receptor in familial male precocious puberty

Familial male precocious puberty (FMPP) is a gonadotropin-independent disorder that is inherited in an autosomal dominant, male-limited pattern. A heterozygous mutation encoding substitution of Asp578 with Gly in transmembrane helix 6 of the G protein-coupled receptor for luteinizing hormone (LHR) has been found in affected males from nine American FMPP families. Cells expressing the mutant LHR exhibit markedly increased cyclic adenosine monophosphate (cAMP) production in the absence of agonist, suggesting that autonomous Leydig cell activity in FMPP is caused by a constitutively activated LHR. We have now analyzed genomic DNA from affected males from six additional FMPP families. PCR was used to amplify a fragment of the LHR gene encoding amino acid residues 441-594. None of the six new samples contained the Asp578-->Gly mutation, as indicated by absence of digestion with MspI. PCR products were then screened for heterozygous mutations using temperature-gradient gel electrophoresis. DNA fragments from two of the patients migrated abnormally. Direct sequencing of PCR product from one affected German male revealed a heterozygous mutation (ATG-->ATA) encoding Met571-->Ile at the cytoplasmic end of helix 6, the same mutation that has been reported in another European FMPP kindred. Affected males in the second family had a novel Thr577-->Ile mutation (ACC-->ATC). Mutations in different portions of the LHR or in a different gene may be responsible for disease in the other FMPP kindreds. Agonist binding and functional coupling of the mutant receptors to the cAMP and inositol phosphate pathways were studied by transiently expressing them in COS-7 cells. Agonist affinity was unaffected by the mutations.(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.

Continuous insulin infusions in neonates: pharmacologic availability of insulin in intravenous solutions

Continuous insulin infusion is sometimes used in very low birth weight infants with glucose intolerance. We studied the availability of insulin to the neonate by means of a laboratory-simulated clinical infusion under both flushed and non-flushed conditions. Although loss of insulin was noted with both solutions (0.5 U/ml), under the nonflushed condition only 55.9% of the prescribed dose for the first 2 hours was delivered before the delivery rate of the flushed system, 71.4%, was approached. These findings have implications for neonatal insulin administration.

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)

The influence of luteinizing hormone and insulin on sex steroids and sex hormone-binding globulin in the polycystic ovarian syndrome

OBJECTIVE

To examine the relationship between hyperinsulinemia, sex hormone-binding globulin (SHBG), and body mass index (BMI) on LH-induced hyperandrogenemia in patients with polycystic ovarian syndrome (PCOS).

DESIGN

Insulin responses during an oral glucose tolerance test (OGTT) were assessed in 25 consecutive women with PCOS and 20 control women matched for BMI. Insulin responses and sensitivity (SI) were also determined using a frequently sampled intravenous glucose tolerance test (IVGTT).

SETTING

The clinical research center at a university medical center.

MAIN OUTCOME MEASURES

Serum LH, SI, and basal, peak, and area under the curve (AUC-insulin responses) were determined and correlated with SHBG, androstenedione (A), T, and free T concentrations.

RESULTS

Compared with controls, the AUC-insulin response during OGTT was greater in PCOS, with an average increase of 44%. During IVGTT, AUC-insulin response was also significantly higher in PCOS versus controls, with an average increase of 53%. In addition, SI was reduced in PCOS versus controls with an average decrease of 53%. The average differences in oral- and intravenous-glucose-induced hyperinsulinemia and in insulin sensitivity between PCOS and controls were relatively constant across the entire physiological range of BMI. In PCOS, baseline LH showed strong positive correlations with baseline A and T. However, there were no significant correlations between either basal, peak, or AUC-insulin response during OGTT and IVGTT with basal T or A concentrations or between insulin and androgen levels measured at 30-minute intervals throughout the OGTT. However, basal, peak, and AUC-insulin responses during OGTT were strongly correlated with fasting SHBG binding capacity.

CONCLUSIONS

These data are consistent with the hypothesis that hyperinsulinemia in PCOS influences the biologically active component of T by lowering SHBG concentrations while having little apparent impact on LH-induced secretion of androgens in vivo.

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)

In vitro insulin-like growth factor-I, growth hormone, and insulin resistance occurs in symptomatic human immunodeficiency virus-1-infected children

Poor growth is a common feature of symptomatic children (Centers for Disease Control stage P2) infected with human immunodeficiency virus-1 (HIV-1). However, several previous studies have failed to show any relationship between serum hormone levels and poor growth. To assess the roles of hormone deficiency and hormone resistance in the development of poor growth in HIV-1-infected children, we studied six asymptomatic Centers for Disease Control stage P1 [height SD score = 0.01 +/- 1.0 (mean +/- SD)], 10 P2 (height SD score = -2.0 +/- 1.0), and six short, normal children (height SD score = -2.4 +/- 1.2). Mean weight:height SD scores were similar in all three groups, suggesting that gross nutritional status did not differ between groups. There were no significant differences between groups with respect to mean plasma levels of IGF-I, thyroid hormones, TSH, and cortisol. As an index of hormone sensitivity, we quantified in vitro colony formation of erythroid progenitor cells, isolated from peripheral blood of study subjects, in response to IGF-I, growth hormone (GH), and insulin. P2 subjects had a quantitative mean reduction in erythroid progenitor cells colony formation in response to IGF-I of 32% compared with P1 subjects (p = 0.001 by analysis of variance) and 21% compared with controls (p = 0.006); in response to GH of 21% compared with controls (p = 0.015); and in response to insulin of 35% compared with P1 subjects (p = 0.038) and 34% compared with controls (p = 0.004).(ABSTRACT TRUNCATED AT 250 WORDS)

Insulin-like growth factor-I unresponsiveness in an Efe Pygmy

The cause of short stature in African Pygmies is unknown, but some evidence suggests that they are GH resistant. Since IGF-I mediates many actions of GH, we sought to determine if Pygmy tissue is responsive to IGF-I. We established HTLV-II-transformed cell lines from 1 Efe Pygmy, 1 African control, and 3 American controls, and quantified in vitro colony formation in response to IGF-I, GH, and insulin, and assessed IGF-I receptor binding. The Pygmy T-cell line showed no clonal responsiveness following stimulation with physiologic concentrations of IGF-I or any concentration of GH, but responded normally to insulin. IGF-I binding studies showed no binding to the Pygmy T-cell line with normal binding to control cells. The primary abnormality in this Pygmy T-cell line is IGF-I resistance at the receptor level with secondary GH resistance.

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.

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.

Insulin and IGF-I stimulate normal and virally transformed T-lymphocyte cell growth in vitro

We used normal and HTLV-II-transformed T-lymphocytes as target cells to study clonal proliferative responses to physiologic and supraphysiologic concentrations of insulin and IGF-I. Responses of both growth factors were measured in the presence and absence of alpha IR-3, and IGF-I receptor-blocking antibody. A biphasic response to insulin was noted in all cell lines with the first peak [78 +/- 6.6% (mean +/- SE) above control] occurring at 1.4 or 1.6 nmol/liter and a second peak (84 +/- 4.9% above control) occurring at 18.0 nmol/liter. Following preincubation with alpha IR-3, the overall clonal profile in response to insulin was significantly reduced [F(7,56) = (10.4, p < .0001] as a result of blunting at high physiologic and supraphysiologic insulin concentrations, i.e., > or = 1.6 nmol/liter. As expected, the overall clonal profile in response to IGF-I was blocked by alpha IR-3 [F(4,32) = 11.6, p < .0001]. These data show that insulin at both physiologic and supraphysiologic concentrations, as well as IGF-I, stimulate virally transformed T-lymphoblast growth. The significant inhibition of growth responses to high concentrations of insulin and to IGF-I by alpha IR-3 suggests mediation of these effects through the IGF-I receptor. Similar studies were performed using freshly isolated, phytohemagglutinin (PHA)-stimulated T-lymphocytes. The overall response to insulin was significantly reduced compared to the profile of transformed T-lymphoblasts [F(7,70) = 4.9, p = .0002] as a result of blunting at physiologic insulin concentrations < 1.8 nmol/liter. In response to IGF-I, the clonal profile of PHA-stimulated T-lymphocytes was slightly reduced compared to that of virally transformed T-lymphoblasts [F(4,40) = 3.4, p = .0174]. Thus, both insulin and IGF-I receptor-effector mechanisms are involved in the growth of virally transformed T-lymphoblasts, whereas the IGF-I receptor-effector mechanism appears to play a more significant role in the growth of normal, mitogen-activated T-lymphocytes.

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.

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.

Insulin and insulin-like growth factor-I responsiveness in polycystic ovarian syndrome

OBJECTIVE

To assess insulin and insulin-like growth factor I (IGF-I) action in women with polycystic ovarian syndrome (PCOS).

DESIGN

Hyperinsulinemia was determined by measuring the insulin responses during a 2-hour oral glucose tolerance test (OGTT). Quantification of in vivo insulin action was determined by a frequently sampled intravenous (IV) OGTT with minimal modeling analysis. In vitro sensitivity to insulin at physiological and supraphysiological concentrations and to IGF-I was assessed by examining colony formation of two hematopoietic cell populations, burst-forming units of the erythroid line (BFU-E) and human leukemia virus immortalized T-cell lines. (The proliferative responses of BFU-E, a primary tissue explant, are presumably conditioned by factors in the immediate blood-borne environment, whereas proliferative responses of T-cell lines are presumed to reflect intrinsic target-cell hormone sensitivity.)

SETTING

Tertiary care research institution.

PATIENTS

Eight patients (4 obese and 4 nonobese) with PCOS and three healthy women for reference controls.

RESULTS

Nonobese (P less than 0.04) and obese patients with PCOS (P less than 0.01) both demonstrated significant hyperinsulinemia after OGTT. In vivo insulin resistance was observed in both nonobese (P less than 0.03) and obese PCOS subjects (P less than 0.01) using frequently sampled IV OGTT. Both nonobese (P less than 0.03) and obese patients with PCOS (P less than 0.01) had blunted in vitro clonal responses of BFU-E, with normal T-cell line clonal responsiveness to physiological levels of insulin and normal BFU-E and T-cell line clonal responses to IGF-I.

CONCLUSIONS

These findings demonstrate the following in both nonobese and obese patients with PCOS: (1) there is in vivo hyperinsulinemia and resistance to insulin action on glucose disposal; (2) with BFU-E, there is in vitro resistance to the mitogenic action of insulin but normal responsiveness to IGF-I; and (3) there is normal in vitro mitogenic responsiveness of T-cell lines to both insulin and IGF-I. The intrinsically normal mitogenic responsiveness to insulin and, especially to IGF-I, whether or not under the influence of the bloodborne milieu, provides a mechanism whereby hyperinsulinemia could directly contribute to the ovarian abnormalities that characterize PCOS.

Pediatric germ cell and human chorionic gonadotropin-producing tumors. Clinical and laboratory features

Germ cell tumors may cause various aberrations in pubertal development. In prepubertal boys, these tumors may secrete human chorionic gonadotropin, resulting in precocious puberty. Human chorionic gonadotropin and alpha-fetoprotein are both useful as germ cell tumor markers in the diagnosis and detection of recurrence. Pregnancy-specific beta 1-glycoprotein, another oncoplacental antigen, has been used as a tumor marker for trophoblastic neoplasms, but not previously for human chorionic gonadotropin-producing tumors associated with precocious puberty. Patients with germ cell tumors may also have abnormal karyotypes. Herein, we describe six male pediatric patients with germ cell tumors and pubertal derangements seen during an 8-year period. We confirm the high incidence of associated sexual precocity, the usefulness of alpha-fetoprotein, human chorionic gonadotropin, and pregnancy-specific beta 1-glycoprotein as tumor markers in the diagnosis and follow-up of these patients, and the occurrence of sex chromosomal abnormalities.

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.

Surgical management of islet cell dysmaturation syndrome in young children

Islet cell dysmaturation syndrome (ICDS) encompasses the causes of infantile hyperinsulinemic hypoglycemia histologically described as islet cell hyperplasia, pancreatic adenomatosis and nesidioblastosis. Eleven infants underwent 14 pancreatic resections for ICDS from 1965 to 1990 at the University of California at Los Angeles Medical Center for severe hypoglycemia unresponsive to medical therapy. Seizures were the presenting symptoms of hypoglycemia in eight infants. Six patients had nesidioblastosis, four had islet cell hyperplasia and one patient had an adenoma with histologically normal pancreatic islet cells. Four neonates underwent 80 per cent pancreatic resection; three with nesidioblastosis required reoperation (90 to 95 per cent resection). Four older infants underwent 80 per cent pancreatic resection but required diazoxide for less than six months postoperatively. Three infants underwent 90 to 95 per cent pancreatic resection. None have required reoperation or postoperative medications. All infants are normoglycemic without pancreatic exocrine insufficiency and none had postoperative complications. Five infants had preoperative neurologic impairment, with three having severe retardation; all showed some improvement postoperatively, but only one infant now has normal findings on neurologic examination. Early diagnosis and aggressive surgical resection should minimize neurologic complications of the ICDS.

Growth hormone mediates the growth of T-lymphoblast cell lines via locally generated insulin-like growth factor-I

It has become evident that locally produced insulin-like growth factors-I and -II (IGF-I and IGF-II) play an important role in the medication of GH action upon tissues. To explore this concept with respect to immunocompetent cells, we analyzed IGF production and clonogenic responsiveness of immortalized human T-cell lines established from seven normal controls and four Laron dwarfs. While the normal T-cell lines showed significant augmentation of basal colony formation in response to both IGF-I and GH, little increase in clonogenesis in response to GH was seen with the Laron T-cell lines. Assay of basal and GH-stimulated conditioned media demonstrated low, but measurable, levels of IGF-I and IGF-II from both normal and Laron T-cells. Under serum-free incubation conditions, GH stimulation of normal T-cell lines failed to generate significant increases in mean IGF-I or IGF-II concentration and no increase in the mean IGF-II concentration in conditioned medium were observed after GH stimulation of Laron T-cell lines. Nevertheless, the increased cloning efficiency of the normal T-cell lines in response to either GH or IGF-I was nearly completely abrogated by preincubation of cells with antibodies to either IGF-I or the type I IGF receptor. These studies, thus, support a role for locally generated IGF-I in the mediation of GH action on T-lymphocytes and indicate that this effect is mediated via the type I IGF receptor.