Vascular endothelial growth factor (VEGF) levels in short, GH treated children: a distinct pattern of VEGF-C in Noonan syndrome.

CONTEXT: Noonan syndrome (NS) is characterized by short stature and elevated risk of lymphedema. The mechanism underlying lymphedema may be mediated by vascular endothelial growth factors (VEGFs). OBJECTIVE: To assess the effect of growth hormone (GH) treatment on plasma insulin-like growth factor (IGF)-1, VEGF-A and VEGF-C levels in patients with NS as compared to short GH-sufficient children. DESIGN: Retrospective, comparative. SETTING: Endocrinology department of a tertiary pediatric medical center. PATIENTS AND METHODS: Plasma IGF-1, VEGF-A and VEGF-C levels were measured before and during GH treatment in 6 patients with NS and 18 age-matched short subjects (Turner, idiopathic short stature and small for gestational age). MAIN OUTCOME MEASURES: Changes in plasma VEGF and IGF-1 levels. RESULTS: Baseline IGF-1 SDS levels were slightly lower in NS patients compared with controls; IGF-1 response to GH therapy was markedly lower in NS patients compared with controls (p = 0.017). Mean baseline VEGF-A levels were similar in NS patients and controls whilst mean baseline VEGF-C levels were significantly lower in the NS group as compared with controls (p = 0.022). Plasma VEGF-A and VEGF-C levels did not significantly change during GH treatment in the study cohort. No correlation was found between VEGF-C levels and levels of IGF-1, VEGF-A and auxological parameters, either before or during GH administration. CONCLUSION: Children with NS have a distinct growth factor profile including low basal VEGF-C and flattened IGF-1 response to GH. Further studies are needed to confirm our findings and to elucidate the interaction between VEGF-C levels and lymphedema.

A novel MKRN3 missense mutation causing familial precocious puberty.

Central precocious puberty may be familial in about a quarter of the idiopathic cases. However, little is known about the genetic causes responsible for the disorder. In this report we describe a family with central precocious puberty associated with a mutation in the makorin RING-finger protein 3 (MKRN3) gene. A novel missense mutation (p.H420Q) in the imprinted MKRN3 gene was identified in the four affected siblings, in their unaffected father and in his affected mother. An in silico mutant MKRN3 model predicts that the mutation p.H420Q leads to reduced zinc binding and, subsequently, impaired RNA binding. These findings support the fundamental role of the MKRN3 protein in determining pubertal timing.

A family with a novel termination mutation in hepatic nuclear factor 1α in maturity-onset diabetes of the young type 3 which is unresponsive to sulphonylurea therapy.

BACKGROUND: Maturity-onset diabetes of the young (MODY) is a monogenic form of diabetes mellitus. AIMS: To identify the genetic basis in a family with 3 generations of diabetes and to assess the concordance between the genotype and phenotype. METHODS: A molecular analysis was performed on genomic DNA using polymerase chain reaction, denaturing gradient gel electrophoresis, and sequencing. A mixed-meal tolerance test (MMTT) was performed with/without glibenclamide. Abdominal ultrasonography was performed on all family members with diabetes due to the location of the mutation. RESULTS: A novel c.618G>A, p.W206X termination mutation was identified in the hepatic nuclear factor 1α (HNF1α) gene. The mutation was identified in the proband and 8 of the 14 family members tested. An MMTT stimulus (±2.5 and 5 mg glibenclamide) produced a similar glucose profile and C-peptide graph in both the obese proband and her nonobese mother, showing no effect of the glibenclamide. No evidence of liver adenomas was found in the abdominal ultrasonography. CONCLUSIONS: We described a novel c.618G>A, p.W206X mutation in HNF1α associated with MODY 3 but not with hepatocellular adenoma. In contradistinction to most MODY 3 mutations, treatment with sulphonylurea was found to be a clinically ineffective alternative to insulin therapy.

Effects of a twelve-week randomized intervention of exercise and/or diet on weight loss and weight maintenance, and other metabolic parameters in obese preadolescent children.

AIMS: To compare the short- and long-term effects of intervention programs on body weight and cardiometabolic risk factors. METHODS: 162 obese children (6-11 years) were randomly assigned to three 12-week interventions with a 9-month follow-up period: exercise (E): 90 min moderate exercise 3 days/week (n = 52); diet (D): balanced hypocaloric diet, weekly meetings with dietician (n = 55), and diet + exercise (D+E) (n = 55). Changes in anthropometric variables, cardiometabolic profile and psychological outcome were assessed. RESULTS: At 12 weeks BMI-SDS, cardiometabolic profiles, and psychological score improved in all groups. The decrease in BMI-SDS was greater in D and D+E compared with E (p < 0.001), without a significant difference between the first two groups. Waist circumference and LDL cholesterol decreased more in D+E compared with E (p = 0.026 and p = 0.038, respectively). The increase in adiponectin was greater in D and D+E compared with E (p = 0.004). Anthropometric and cardiometabolic variables regressed without significant differences between groups after 9 months. However, BMI-SDS, body fat percentage and LDL cholesterol were lower compared to baseline. CONCLUSIONS: Diet alone or combined with exercise are the most effective short-term interventions for weight loss and improved cardiometabolic profiles, without a difference between them. In the long term, obese children need the long-term support of maintenance approaches.

Growth without growth hormone and similar dysmorphic features in three patients with sporadic combined pituitary hormone deficiencies.

BACKGROUND/AIMS: Mutations in the HESX1 gene are associated with a broad spectrum of phenotypes: septo-optic dysplasia, midline defects, pituitary abnormalities with consequent hypopituitarism, isolated growth hormone (GH) deficiency or combined pituitary hormone deficiencies (CPHD). This study examined the prevalence of mutations in the HESX1 gene in patients with CPHD. PATIENTS/METHODS: Sixty patients with sporadic CPHD without septo-optic dysplasia were screened for mutations in HESX1. RESULTS: Three patients were found to be heterozygous for the same Asn125Ser variant in the HESX1 gene. In all 3, panhypopituitarism was presented in the neonatal period, manifested by severe hypoglycemia and neonatal jaundice in 2 patients and respiratory distress in 1. Remarkable findings from physical examination included coarse face; prominent, large, low-set ears; and skeletal abnormalities. Magnetic resonance imaging, performed in 2 patients, revealed a hypoplastic anterior and ectopic posterior pituitary without other midline anomalies. Despite persistent GH deficiency and undetectable levels of insulin-like growth factor 1, all patients had normal linear growth along the 10-25th percentile without GH therapy. CONCLUSION: The present study expands the clinical picture of HESX1 mutations by demonstrating that patients heterozygous for Asn125Ser may have a severe endocrinologic and neuroradiologic phenotype and similar dysmorphic features appearing very early in life.

Kisspeptin serum levels in girls with central precocious puberty.

OBJECTIVE: Central precocious puberty (CPP) causes early epiphyseal maturation, and early initiation of treatment improves final height. Unfortunately, there is no one parameter that can distinguish CPP from premature thelarche (PT), which is self-limited and requires no therapy. In animal models, kisspeptin, the ligand for the G-protein coupled receptor GPR54, was found to induce precocious activation of the gonadotrophic axis. Data on kisspeptin levels in girls with precocious puberty or in healthy prepubertal girls are lacking. We measured blood kisspeptin levels in girls with CPP and evaluated its potential as a clinical marker for CPP. Design This was a case-control study. PATIENTS: Thirty-one girls clinically diagnosed with CPP and 14 prepubertal age-matched healthy controls. Measurements Kisspeptin blood levels. RESULTS: Kisspeptin levels were significantly higher in the girls with CPP than in the controls: 14.62 +/- 10.2 pmol/l vs. 8.35 +/- 2.98 pmol/l, P < 0.05. Within the CPP group, there were no significant differences between the girls with a peak LH >5.0 IU/l and those with a peak LH

Nutrition-induced catch-up growth at the growth plate.

The effect of 40% food restriction (FR) and replenishment on the growth hormone (GH) and insulin-like growth factor-I (IGF-I) axis in the epiphyseal growth plate (EGP) was examined in a mouse model. Changes in RNA and protein levels were evaluated with real time PCR and immunohistochemistry, respectively, and serum levels of IGF-I and leptin were measured with radioimmunoassay. Dramatic changes in weight, tibial length and EGP height were observed following 10 days of 40% FR. The protein levels of IGF-I receptor (IGF-IR) and GH receptor (GHR), which were reduced during FR, increased during catch-up growth without an apparent change in the level of their RNA. The levels of type II and X collagens were unchanged. Serum IGF-I and leptin levels were reduced during FR and increased during catch-up growth. Following 40% FR, there was a significant decrease in the level of GHR and IGF-IR in the EGP which may explain the reduced effect of GH treatment in malnourished animals and children.

Nutrition-induced catch-up growth increases hypoxia inducible factor 1alpha RNA levels in the growth plate.

Although catch-up growth is a well-known phenomenon, the local pathways at the epiphyseal growth plate that govern this process remain poorly understood. To study the mechanisms governing catch-up growth in the growth plate, we subjected prepubertal rats to 10 days of 40% food restriction, followed by a renewal of the regular food supply to induce catch-up growth. The animals were weighed daily, and their humeral length was measured at sacrifice. The proximal tibial epiphyseal growth plates (EGPs) were studied, and findings were compared with EGPs from animals fed ad libitum and animals under food restriction. The gene expression profile in the growth plates was examined using DNA microarrays, and the expression levels of selected genes were validated by real-time polymerase chain reaction. To localize gene expression in different growth plate zones, microdissection was used. Protein levels and localization were examined using immunohistochemistry. We showed that the expression level of 550 genes decreased during food restriction and increased during catch-up growth, starting already one day after refeeding. HIF-1alpha, as well as several of its downstream targets, was found among these genes. Immunohistochemistry showed a similar pattern for HIF-1alpha protein abundance. Additionally, HIF-1alpha mRNA and protein levels were higher in the proliferating than in the hypertrophic zone, and this distribution was unaffected by nutritional status. These findings indicate that nutrition has a profound effect on gene expression level during growth plate growth, and suggest an important role for HIF-1alpha in the growth plate and its response to nutritional manipulation.

Four novel mutations, including the first gross deletion in TCF1, identified in HNF-4alpha, GCK and TCF1 in patients with MODY in Israel.

Maturity onset diabetes of the young (MODY) is characterized by a primary defect in insulin secretion with non-ketotic hyperglycemia, monogenic autosomal dominant mode of inheritance, age at onset less than 25 years, and lack of autoantibodies. The aim of this study was to characterize the genetic basis of MODY in different ethnic groups in the Israeli population. Fifty-nine unrelated Israeli patients with MODY were assessed for mutations in the three common MODY genes: hepatocyte nuclear factor (HNF)-4alpha, glucokinase (GCK), and transcription factor 1 (TCF1). Overall, 11 mutations in 12 unrelated families were found (20.3% of patients), for a relative frequency of 1.7% for MODY1, 8.5% for MODY2, and 10.1% for MODY3. Four mutations were novel, including the first gross deletion ever described in the TCF1 gene. The low overall mutation frequency found here may suggest the involvement of other, yet unidentified, genes in the etiology of MODY in Israel.

Leptin stimulates parathyroid hormone related peptide expression in the endochondral growth plate.

We have previously shown that growth plate chondrocytes expressed the long form of leptin receptor, and that within the growth plate, leptin stimulated cell proliferation and differentiation and epiphyseal growth in a balanced manner. These three cell processes are known to be regulated by the interactions of parathyroid hormone-related peptide (PTHrP) and Indian hedgehog (Ihh) protein. The aim of the present study was to examine the effect of leptin on the PTHrP/Ihh feedback loop. The effect of leptin was investigated in vivo in pair-fed experiments in ICR mice, and ex vivo in mandibular condyle explants incubated with leptin. Immunohistochemistry and in situ hybridization showed that in the pair-fed in vivo system as well as in the organ culture, leptin increased the level of PTHrP and reduced that of Ihh. Leptin may affect chondrocyte proliferation and differentiation by activating the PTHrP/Ihh growth-restraining feedback loop in the postnatal growth plate.

A new mutation in the growth hormone-releasing hormone receptor gene in two Israeli Arab families.

BACKGROUND: Mutations in the GHRH receptor gene (GHRH-R) are emerging as a common cause of familial isolated GH deficiency (IGHD). DESIGN: We searched for GHRH-R mutations in 10 patients with IGHD of Israeli-Arab origin, belonging to two highly consanguineous families. METHODS: Analysis of the 13 coding exons, the intron-exon boundaries, and the proximal promoter of the GHRH-R was performed by denaturing gradient gel electrophoresis. Abnormally migrating bands were sequenced. The newly found mutation was inserted into GHRH-R cDNA. Wild type and mutant receptor were expressed in Chinese hamster ovary (CHO) cells, and the cAMP response to GHRH was measured. RESULTS: All patients were homozygous for a novel GHRH-R missense mutation in exon 11 that replaces arginine with cysteine (R357C). Functional assay demonstrated complete inactivity of the mutant receptor in vitro. The prevalence of the mutant allele in the Israeli-Arab population was found to be 2%. All the patients had low but detectable GH reserve, proportionate short stature, and growth retardation since early childhood, with good growth response to GH treatment. Magnetic resonance imaging, performed in 3 patients, revealed a normal sized anterior pituitary in one patient evaluated at early childhood, and a borderline hypoplastic gland in the 2 patients evaluated at puberty. CONCLUSIONS: We describe a novel missense mutation in the GHRH-R. The high incidence of the mutant allele in Israeli Arabs suggests that the mutation may be a common cause of familial IGHD in this population.

Effect of sex hormone administration on circulating ghrelin levels in peripubertal children.

BACKGROUND: Ghrelin levels gradually decrease throughout childhood and with advancing pubertal stage. The change during puberty is more pronounced in boys than girls. OBJECTIVE: The objective of the study was to investigate whether the pubertal drop in ghrelin secretion is modified by the increase in sex hormones. PATIENTS AND METHODS: Ghrelin levels were measured in 34 short peripubertal children (17 boys and 17 girls) aged 8-12.5 yr before and after sex hormone priming for GH stimulation testing. RESULTS: In boys, priming with testosterone increased testosterone to pubertal levels (23.7 +/- 7.1 nmol/liter), which in turn induced a marked decrease in ghrelin (from 1615.8 +/- 418.6 to 1390.0 +/- 352.0 pg/ml) and leptin (from 8.0 +/- 4.5 to 5.8 +/- 3.2 ng/ml) and an increase in IGF-I (from 162.7 +/- 52.8 to 291.1 +/- 101.6 ng/ml) (P < 0.001 for all parameters). In girls, priming with estrogen led to a supraphysiological increase in estradiol levels (1313.8 +/- 438.0 pmol/liter), which had no effect on ghrelin, leptin, or IGF-I. There was no correlation between ghrelin levels and levels of sex hormones, leptin, or body mass index in either boys or girls. CONCLUSIONS: A pharmacological increase in sex hormones is associated with a marked decline in circulating levels of ghrelin in boys but not girls. Additional longitudinal studies through puberty are needed to elucidate the physiological interaction between sex hormones and ghrelin.

Three novel mutations in POU1F1 in Israeli patients with combined pituitary hormone deficiency.

BACKGROUND: POU1F1, a pituitary-specific transcription factor of the class 1 POU family, is crucial for the development and differentiation of the anterior pituitary gland. Mutations in the POU1F1 gene have been shown to be responsible for a syndrome of combined pituitary hormone deficiency (CPHD), including prolactin, growth hormone and thyroid-stimulating hormone deficiencies. METHODS: Five patients with CPHD from three families were evaluated. The clinical and biochemical data were taken from the medical records. DNA was analyzed by polymerase chain reaction (PCR), denaturing gradient gel electrophoresis (DGGE), and sequencing. RESULTS: Molecular analysis yielded three novel mutations in POU1F1: W193X, Q242R (-2 bp), and F262L. CONCLUSIONS: Three novel POU1F1 mutations were detected in Israeli patients with CPHD. Two of them, a W193X missense mutation and a deletion of two adenine bases at position 242Q, may lead to the production of a truncated protein that lacks the entire POU homeodomain or part of it, respectively. The third mutation, F262L, resides in the POU homeodomain and hence might change the activity of the protein.

The aromatase inhibitor letrozole increases epiphyseal growth plate height and tibial length in peripubertal male mice.

Sex hormones may influence longitudinal growth, either indirectly, by affecting the growth-hormone-insulin-like growth factor I (IGF-I) axis, or directly, by affecting changes within the epiphyseal growth plate (EGP). The aim of the present study was to investigate the effects of letrozole, an aromatase inhibitor, on longitudinal growth and changes in the EGP in vivo. Eighteen peripubertal male mice were divided into three groups. The first group was killed at baseline, the second was injected with letrozole (Femara) s.c., 2 mg/kg body weight/day, for 10 days, and the third was injected with the vehicle alone. Serum testosterone levels were found to be significantly higher in the treated group than in the controls. Letrozole induced a significant increase in body weight, tail length and serum growth hormone level, but had no significant effect on the level of serum IGF-I. On histomorphometric study, there was a significant increase (12%) in EGP height in the treated animals compared with controls. Immunohistochemistry showed a 3.4-fold letrozole-induced increase in the proliferation of the EGP chondrocytes, as estimated by the number of proliferation cell nuclear antigen-stained cells, and a decrease in the differentiation of the EGP chondrocytes, as estimated by type X collagen staining. Letrozole did not interfere with type II collagen levels. The study group also showed a twofold increase in the number of IGF-I receptor-positive cells compared with controls. In conclusion, the aromatase inhibitor, letrozole, appears to increase the linear growth potential of the EGP in mice.

Leptin reverses the inhibitory effect of caloric restriction on longitudinal growth.

Caloric imbalance, particularly in critical periods of growth and development, is often the underlying cause of growth abnormalities. Serum levels of leptin are elevated in obesity and are low in malnutrition and malabsorption. The aim of the present study was to determine whether leptin integrates energy levels and growth in vivo, as shown previously in our ex vivo experiments, even in the presence of caloric restriction. In the first part of the study, mice were divided into three groups. Two groups were fed ad libitum and received leptin or vehicle only, and the third group was pair-fed with the group injected with leptin to dissociate leptin's effect on growth from its effect on food consumption. Mice given leptin had a significantly greater tibial length than untreated pair-fed animals and a similar tibial length as control mice fed ad libitum despite their lower weight. In addition, leptin significantly increased the overall size of the epiphyseal growth plate by 11%. On immunohistochemistry and in situ hybridization studies, leptin stimulated both the proliferation and differentiation of tibial growth plate chondrocytes without affecting the overall organization of the plate. There was also a marked increase in the expression and level of IGF-IR. In the second part of the study, two groups of mice were fed only 60% of their normal chow; one was injected with leptin, and the other was injected with vehicle alone. Caloric deprivation by itself reduced serum levels of IGF-I by 70% and the length of the tibia by 5%. Leptin treatment corrected the fasting-induced growth deficiency, but further reduced the level of serum IGF-I. These results indicate that leptin stimulates growth even in the presence of caloric restriction independently of peripheral IGF-I.

PROP-1 gene mutation (R120C) causing combined pituitary hormone deficiencies with variable clinical course in eight siblings of one Jewish Moroccan family.

BACKGROUND: PROP-1 gene mutations have been described in patients with combined pituitary hormone deficiencies (CPHD). METHODS: Clinical follow-up and molecular analysis of the PROP-1 gene were performed in 4 affected sisters of one consanguineous family, in whom 8 members had CPHD. RESULTS: The 4 sisters were homozygous for the same R120C mutation. Growth hormone and thyroid-stimulating hormone deficiencies were diagnosed concomitantly in all subjects, but at different ages (5.5-10.8 years). All 8 subjects exhibited complete gonadotropin deficiency with failure of spontaneous sexual maturation. Adrenocorticotropic hormone deficiency developed in only 2 sisters in the 3rd and 4th decades of life. CONCLUSIONS: The CPHD in this family, caused by an R120C mutation, was characterized by clinical phenotypic variability in terms of the severity of hormonal deficiencies and the time of their development. Identifying the mutation does not predict the clinical course. Therefore, continuous follow-up with repeated endocrine evaluations is mandatory to provide proper hormone substitution therapy.

A novel mutation in PIT-1: phenotypic variability in familial combined pituitary hormone deficiencies.

Mutations in PIT-1 have been described in several cases of familial combined pituitary hormone deficiencies. This study describes a novel PIT-1 mutation that was found in two siblings of a highly consanguineous family of Israeli-Arab origin. The missense mutation (G688A) causes a lysine (K) to glutamic acid (E) substitution at codon 230. This codon resides in the first helix of the POU-homeodomain, which is directly involved in DNA binding. This amino acid is conserved in most homeodomain proteins, suggesting that the substitution disrupts the DNA-binding activity of the mutant protein. Two main observations are described: 1. The clinical presentation of the mutation involves intrauterine growth retardation. 2. One sibling had full deficency of growth hormone and thyroid stimulating hormone, whereas the other had only growth hormone deficiency. This is, to the best of our knowledge, a unique expression of a novel PIT-1 mutation.

Homocystinuria in the Arab population of Israel: identification of two novel mutations using DGGE analysis.

This study describes, for the first time, a thorough genetic investigation in Israeli Arab homocystinuric patients. By using a DGGE methodology and sequencing we were able to identify the disease causing mutation in all. Of the mutations that were detected, two are novel: a 785C>G transversion in exon 7 (T262R) and a 5-bp deletion in the 5' of IVS17 including the T in the +2 position that is crucial for correct splicing (g18327-18331del5). In spite of the highly consanguineous nature of this population several different mutations were found. This may suggest that the mutations arose only recently in the population. The results of our study would enable early prenatal diagnosis, genetic counseling and screening for the mutations in population at risk. Hum Mutat 16:372, 2000.

A missense mutation in ColA1 in Jewish Israeli patient with mild osteogenesis imperfecta, detected by DGGE.

Osteogenesis imperfecta (OI) underlies germline mutations in either Col1A1 or Col1A2. Here we describe, for the first time, the use of the denaturing gradient gel electrophoresis (DGGE) technique for mutation analysis of the Col1A1 gene. By employing this technique, we identified a point mutation in a young Jewish Israeli patient with mild OI. The missense mutation, a G to A alteration at position 888, result in a Gly to Arg substitution at codon 79. Furthermore, the patient's mother, who was clinically labeled as OI based solely on the fact that she has blue sclera, was found not to carry this mutation in two different tissues. We suggest that blue sclera alone should not be used as a parameter for the diagnosis of OI, and that DGGE can be effectively used for mutation analysis of the Col1A1 gene.

Differential down-regulation of protein kinase C selectively affects IgE-dependent exocytosis and inositol trisphosphate formation.

Short-term treatment of rat basophilic leukaemia (RBL-2H3) cells with the phorbol ester 12-O-tetradecanoylphorbol 13-acetate (TPA) activates protein kinase C (PKC) and results in the inhibition of the IgE-dependent formation of inositol phosphates, but in the potentiation of serotonin secretion. Long-term treatment with TPA, which depletes the cells of their endogenous PKC, eliminates both Ca2(+)-ionophore- and TPA- as well as IgE-dependent secretion, but it potentiates by 1.7-fold IgE-induced inositol phosphate formation. Taken together, these observations strongly suggest that the dual actions of TPA on IgE-dependent responses are both mediated by PKC. The opposing effects of TPA are differentially down-regulated. Following TPA treatment, the rate by which the cells lose their ability to undergo exocytosis is faster than the rate at which inhibition of inositol phosphates formation is relieved and their production potentiated. In addition, both processes show different sensitivities to inhibitors of PKC action. Whereas IgE-dependent secretion is completely blocked by the PKC inhibitors K252a, H-7 and sphingosine [concns. causing 50% inhibition (IC50 values) = 25 ng/ml 80 microns and 30 microns respectively], these inhibitors do not relieve inhibition of inositol phosphate formation by TPA, nor do they potentiate this response. These results may imply that the bidirectional control exerted by PKC on IgE-dependent responses is mediated by its different isoenzymes.