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Biomedical subjects

S L Drop

Publications and source records attributed to S L Drop.

At least 73 records · Page 4Linked to original sources
PubMed1995

Children born small for gestational age: do they catch up?

Postnatal growth of 724 (423 premature, 301 full-term) small for gestational age infants (SGA, birth length less than the third length percentile (P3) for gestational age) was studied for the first 2 y of life. The study group consisted of all SGA infants who had been admitted over a period of 8 y at the Departments of Neonatology of three University Hospitals in The Netherlands with exclusion of infants with well defined causes for growth retardation, such as chromosomal disorders, syndromes, severe malformations, or complications during the neonatal period or later on. The aim of the study was to describe postnatal growth of SGA infants and to find predictive factors for catch-up growth > or = P3 during the first 2 y of life. The majority (around 85%) of the healthy SGA infants showed catch-up growth to a height > or = P3 during the first 2 y of life. The percentage of premature SGA infants with catch-up growth > or = P3 at 2 y of age (82.5%) was not significantly different from that of full-term SGA infants (87.5%). Birth length SDS was more sensitive than birth weight SDS in predicting catch-up > or = P3 in premature SGA infants. In contrast, birth weight SDS was the best predictor for catch-up > or = P3 in full-term SGA infants. Gestational age, multiple birth, and sex were not significantly associated with catch-up in height > or = P3.(ABSTRACT TRUNCATED AT 250 WORDS)

Birth Weight↗
PubMed1995

Idiopathic isosexual central precocious puberty: magnetic resonance findings in 30 patients.

The purpose of this prospective study was to define the incidence of magnetic resonance imaging (MRI) abnormalities in the brain in patients with idiopathic central precocious puberty without any additional neurological signs and symptoms, and to evaluate the routine use of gadolinium contrast in these patients. 30 patients (29 girls, one boy; age range 1.9-11.9 years) with idiopathic central precocious puberty were studied. MRI of the brain in axial, coronal and sagittal planes was performed before and after administration of gadopentetate dimeglumine, with special attention to the region of the third ventricle. There are three major findings: (1) the height of the pituitary gland is increased up to adult size compared with normal individuals; (2) in four patients (13%) major structural abnormalities were found; three hamartomas of the tuber cinereum and one gliomatous process extending from the chiasm to the optic tract; and (3) the routine use of gadopentetate dimeglumine did not reveal new abnormalities although the lack of enhancement made a positive contribution to diagnostic certainty. We conclude that contrast enhanced MR examination is a safe and reliable method for the exclusion of abnormalities in children with precocious puberty and for the follow-up of those patients in whom abnormalities are present.

Adolescent↗
PubMed1995

IGF, type I IGF receptor and IGF-binding protein mRNA expression in the developing mouse lung.

The IGFs are important mitogens involved in lung growth and development. The regulation of IGF action depends not only on the expression of IGFs and IGF receptors, but also on the modulation of IGF activity by IGF-binding proteins (IGFBPs). In this study, we describe the mRNA expression of IGF-I, IGF-II, type I IGF receptor, IGFBP-2, IGFBP-4 and IGFBP-5 during mouse lung development as studied by in situ hybridization techniques. The IGF, type I IGF receptor and IGFBP-2, -4 and -5 genes were expressed in developing lung as early as embryonal day 12.5. Expression of IGFBPs-1, -3 and -6 was below detection. IGF and IGFBP-2 mRNAs were expressed both in mesenchymal and epithelial cells. Type I IGF receptor transcripts were also observed throughout the developing lung, with the exception of the epithelial cells of the bronchi after embryonal day 15. Furthermore, mRNA expression of IGFBPs-4 and -5 was noted in neighbouring cell types, and after embryonal day 15, co-expression of the type I IGF receptor and IGFBP-4 transcripts was detected. The observed expression patterns imply that the IGFBP-2, -4 and -5 genes are differentially regulated during embryonic development and suggest that each may have a discrete function. A possible role for IGFBPs-2, -4 and -5 is to participate in the regulation of cell-specific IGF responses during mouse lung development.

Animals↗
PubMed1995

Stimulation of hepatic insulin-like growth factor-binding protein-1 and -3 gene expression by octreotide in rats.

It has recently been demonstrated in various clinical experiments that native somatostatin and its long-acting analogues increase circulating levels of insulin-like growth factor-binding protein-1 (IGFBP-1) within 1-2 h, independent of effects on circulating insulin or glucose levels. Using human hepatoma cells in vitro the somatostatin analogue, octreotide, has been shown to increase IGFBP-1 mRNA within 24 h indicative of a direct stimulatory effect of octreotide on IGFBP-1 synthesis. In order to ascertain whether octreotide acutely stimulates IGFBP-1 mRNA in vivo, placebo or two doses of octreotide were injected subcutaneously into three groups of rats. One hour after saline or octreotide administration, liver, kidney and serum were obtained for the measurement of IGFBPs-1 to -6 mRNA in tissue and IGFBPs and IGF-I in serum. Octreotide increased liver IGFBP-1 (562%) and IGFBP-3 (23%) mRNA expression with a concomitant rise in the circulating 30 kDa (106%) and 38-42 kDa (23%) IGFBPs. No detectable changes were seen in other liver IGFBP transcripts, other circulating IGFBPs or in any of the kidney IGFBP transcripts. Serum IGF-I increased by 37% in the animals receiving the high octreotide dose. No concomitant changes were observed in glucose or insulin levels. These data show that octreotide acutely stimulates hepatic IGFBP-1 and -3 mRNA in vivo in rats. The stimulating effect on IGFBP-3 presents a possible hitherto unknown form of regulation of IGFBP-3 whilst the effect on IGFBP-1 indicates that the stimulatory effect of octreotide on circulating IGFBP-1 described in clinical trials may be due to increased hepatic production. The present findings may be of importance in the clinical use of octreotide.

Animals↗
PubMed1994

Growth hormone treatment in growth-retarded adolescents after renal transplant.

Growth failure is a psychosocial problem for many patients who have undergone renal transplantation. 18 adolescents (mean age 15.6, range 11.3-19.5) with severe growth retardation after renal transplantation were treated with biosynthetic growth hormone (GH) for 2 years. All received prednisone, administered daily or on alternate days, with azathioprine and/or cyclosporin A. 16 were blindly assigned to one of two GH doses (4 vs 8 IU per m2 per day). Growth, bone maturation, renal graft function, plasma insulin-like growth factors, serum binding proteins, and other biochemical parameters were checked regularly. Glomerular filtration rate and effective renal plasma flow were tested with 125I-Thalamate and 131I-Hippuran. Data on growth and glomerular filtration rate during GH treatment were also compared with those of matched non-GH-treated controls. Mean (standard deviation) increment in height after 2 years of GH was 15.7 (5.1) cm, significantly greater (p < 0.0001) than in matched controls, 5.8 (3.4) cm. Results were similar for the two GH dosage groups. Bone maturation was not accelerated. Glomerular filtration rate and effective renal plasma flow did not change significantly. The incidence of a > 25% reduction in glomerular filtration rate over 2 years was not significantly higher in GH-treated patients than in non-GH-treated controls (39% vs 32%, p = 0.97). Although a few patients had deterioration of graft function, we could not find a relation with GH treatment. Our results show that sustained improvement of height can be achieved with GH in severely growth-retarded adolescents after renal transplantation.

Adolescent↗
PubMed1994

cDNA cloning and mRNA expression of the six mouse insulin-like growth factor binding proteins.

The insulin-like growth factor binding proteins (IGFBPs) comprise a family of six distinct proteins which modulate insulin-like growth factor action. We have isolated cDNAs encoding the six mouse IGFBPs (mIGFBPs). In addition, we studied the mRNA expression of the six mIGFBPs during development and in various adult tissues. Our results show that each of the six mIGFBPs is highly homologous to their human and rat counterparts, whereas only the N and C terminal ends are conserved between the six mIGFBPs. Northern blotting revealed that mIGFBP-2, -3, -4 and -5 genes are already expressed at gestational day 11.5, suggesting a role for these mIGFBPs in embryonal development. In liver, a peak of mIGFBP-1 mRNA expression was found around birth, suggesting a function for mIGFBP-1 in the newborn mouse. Finally, tissue-specific expression of the six mouse IGFBP genes was observed in adult tissues suggesting different roles or modes of actions in adult life.

Amino Acid Sequence↗
PubMed1994

Endogenous and stimulated GH secretion, urinary GH excretion, and plasma IGF-I and IGF-II levels in prepubertal children with short stature after intrauterine growth retardation. The Dutch Working Group on Growth Hormone.

OBJECTIVE: The pathophysiological mechanisms underlying the failure of catch up-growth in children with short stature after intrauterine growth retardation (IUGR) remain obscure. Since GH secretion disturbances might play a role in the growth retardation of these children we have investigated various aspects of the GH/IGF axis. DESIGN: Cross-sectional study in one group of patients. PATIENTS: Forty prepubertal children (15 girls/25 boys; mean age (range) 7.5 years (3.4-10.8)) with short stature (height below the third centile) after IUGR, defined as a birth length below the third centile for gestational age, were studied. MEASUREMENTS: GH secretion was determined by a 24-hour plasma GH profile (sampling every 20 minutes) and, on a separate occasion, by a standard arginine provocation test (ATT). Plasma IGF-I and IGF-II levels were measured at the start of the GH profile. Urine was collected to measure urinary GH levels. Plasma and urinary GH were determined by double antibody RIA. IGF-I and IGF-II were determined by specific RIA after acid chromatography. The 24-hour GH profiles were analysed using Pulsar. RESULTS: Endogenous GH secretion was similar for boys and girls. Boys had significantly lower mean GH levels compared to healthy controls. Forty per cent of the children met our criteria for a normal 24-hour GH profile (group A; n = 16) and 60% (n = 24) did not. We subdivided these 24 children into two groups: group B (n = 14) (children with either mean GH levels less than controls but with at least one spontaneous GH peak above 20 mU/l and children with normal mean GH levels but with no GH peak above 20 mU/l (subnormal 24-hour GH profile)) and group C (n = 10) (children with mean GH levels less than controls and no GH peak above 20 mU/l (low 24-hour GH profile)). The GH secretory abnormalities were due to a decrease in pulse amplitude, not in pulse frequency. Mean (SD) maximal GH response during ATT was 22.3 (12.1) mU/l. Nineteen children (47.5%) had a maximal GH value < 20 mU/l. Moderate, but significant, correlations were found between several 24-hour GH profile characteristics and the maximal GH response during ATT (r = 0.31-0.35; P < 0.05). Mean (SD) overnight urinary GH excretion was 3.8 (2.1) and 4.4 (3.5) microU/night for boys and girls, respectively. Compared to healthy schoolchildren, overnight urinary GH was lower in boys, but not in girls. Mean (SD) IGF-I and IGF-II SDS levels for chronological age were -0.88 (1.40) and -0.64 (1.48), respectively. Plasma IGF-I and IGF-II levels were significantly reduced compared to controls. Height SDSCA or height velocity SDSCA did not correlate with either spontaneous or stimulated GH secretion, urinary GH excretion or plasma IGF-I or IGF-II levels. CONCLUSIONS: Our study indicates that 50-60% of children with short stature after intrauterine growth retardation have 24-hour GH profile abnormalities and/or subnormal responses to arginine provocation, while mean plasma IGF-I and IGF-II levels are significantly reduced, indicating GH insufficiency. Urinary GH excretion is lower in boys, but not in girls. The precise mechanism of the failure to catch up growth needs further elucidation. It seems justified to start clinical trials in order to investigate whether treatment with exogenous GH might be beneficial for these children.

Arginine↗
PubMed1994

De novo deletion (2) (p11.2p13): clinical, cytogenetic, and immunological data.

We report a case of a boy with a de novo interstitial deletion of chromosome (2) (p11.2p13). Clinical features included dysmorphism of the face, genital region, and limbs, psychomotor retardation, and vitiligo. A reduced ratio of immunoglobulin (Ig) light chain expression (kappa/lambda ratio: 0.7) was found, compatible with deletion of one Ig kappa allele on chromosome 2p12. The patient had no clinical or laboratory signs of immunodeficiency.

Abnormalities, Multiple↗
PubMed1994

Growth after renal transplantation in prepubertal children: impact of various treatment modalities.

A retrospective study evaluated posttransplant growth of 70 prepubertal children during the first 2 y after renal transplantation (RTx). Immunosuppressive treatment consisted of prednisone administered either daily or on alternate days in combination with either azathioprine or cyclosporin A. The increment in height standard deviation score for chronologic age during the first 2 y after RTx was less than 0.5 SD for 70% of the study population. The predictive factors for posttransplant growth were determined by evaluating several factors and treatment modalities singly and simultaneously in a multiple regression analysis. Patients with the most severe growth retardation at RTx appeared to have the most pronounced growth spurt after RTx, but even they never had complete catch-up growth, and 2 y after RTx they were still shorter than those with less severe growth retardation at RTx. Alternate-day instead of daily prednisone administration had a significantly positive influence, whereas a high cumulative dose of prednisone, azathioprine instead of cyclosporin A therapy, and a persistently reduced GFR (GFR < 50 mL/min/1.73 m2) had a significantly negative influence on catch-up growth during the 2 y after RTx. Other factors, such as gender, chronologic and bone age at RTx, primary renal disease, duration of initial dialysis, repeat RTx, and target height SD score for chronologic age, whether evaluated singly or simultaneously with other significant factors, appeared to have no significant influence on post-RTx growth. Thus, 70% of the prepubertal children do not experience appreciable catch-up growth during the first 2 y after RTx. Optimization of pretransplant height appears very important. Immunosuppressive treatment with cyclosporin therapy in combination with a minimal dose of alternate-day prednisone would then result in optimal post-transplant growth, particularly if the GFR remains above 50 mL/min/1.73 m2).

Azathioprine↗
PubMed1994

A practical approach to the detection of androgen receptor gene mutations and pedigree analysis in families with x-linked androgen insensitivity.

Androgen insensitivity syndrome (AIS) is an X-linked disorder in which defects in the androgen receptor gene have prevented the normal development of both internal and external male structures in 46,XY individuals. This survey reports the analysis of 11 AIS subjects. The androgen receptor gene of these subjects was analyzed using polymerase chain reaction (PCR)-single-strand conformation polymorphism analysis and sequencing or sequencing of PCR-amplified androgen receptor gene fragments alone. In total, 10 single base changes and one partial gene deletion were detected. Seven single base changes resulted in an amino acid change, one resulted in the introduction of a premature stop codon, one event represented a single base insertion resulting in a frame-shift, and one single base change affected a donor splice site. The androgen receptor protein in genital skin fibroblasts from several patients was studied with respect to molecular mass after immunoprecipitation and SDS-PAGE. Two patients expressed a truncated receptor protein in agreement with the established genomic mutation. Pedigree analysis was performed to identify possible carriers for the syndrome in families of AIS patients using single-strand conformation polymorphism and restriction site analysis of PCR products. In one case, the polymorphic (CAG)n(CAA) repeat in exon 1 encoding a polyglutamine stretch was used to identify the mutant allele in a family with X-linked partial androgen insensitivity before the identification of the actual genomic mutation. PCR-single-strand conformation polymorphism analysis proved to be a fast and reliable technique to screen for androgen receptor gene mutations and to study the androgen receptor gene of family members of AIS-affected individuals.

Base Sequence↗
PubMed1994

Final height and its predictive factors after renal transplantation in childhood.

A retrospective study is reported assessing final height (FH) and its predictive factors in 52 patients (31 male, 21 female) who underwent renal transplantation (RTx) before the age of 15 y. They received prednisone daily or on alternate days as well as azathioprine. The study period covered 20 y. FH remained below the third height percentile [height standard deviation score for chronologic age (hSDSCA) < -1.88] for most of these patients (77% males, 71% females). Median (range) FH was 165.0 (143.0-176.8) cm in males and 153.0 (135.0-168.4) cm in females. Median difference between FH and target height was 15.0 and 15.4 cm for males and females, respectively. For both sexes, the median hSDSCA was already below -1.88 at the start of the first hemodialysis, after which it decreased significantly until the first RTx. After RTx, there was no significant improvement of hSDSCA. The predictive factors for FH were determined by evaluating various factors simultaneous in a multiple regression analysis. This analysis provided a regression equation for predicting FH. A higher hSDSCA at the time of the first RTx and alternate-day versus daily prednisone therapy both had a significantly positive influence on FH, whereas a longer duration of reduced GFR (< 50 mL/min/1.73 m2) had a significantly negative effect on FH. Other factors such as age or bone age at first RTx, primary renal disease, duration of initial dialysis, repeat RTx, and the cumulative dose of prednisone did not influence FH significantly. In conclusion, 71-77% of patients that received their first renal transplant before the age of 15 ended up with severely short adult stature. Optimization of the hSDSCA at first RTx appears very important. Long-term administration of prednisone on alternate days would then result in optimal FH, particularly if the GFR remains above 50 mL/min/1.73 m2.

Adolescent↗
PubMed1994

Double blind trial comparing the effects of two doses of growth hormone in prepubertal patients with chronic renal insufficiency.

Growth retardation is a major problem for children with chronic renal insufficiency (CRI). Recent studies have convincingly shown that recombinant human GH accelerates growth significantly, but the optimal GH dose with regard to long term growth response and safety has not yet been established. GH therapy was given to 23 prepubertal children (18 boys and 5 girls; mean +/- SD age, 7.1 +/- 3.6 yr; range, 1.6-14.1) with CRI and severe growth retardation in a double blind, dose-response trial. Patients were randomly assigned to either 2 or 4 IU GH/m2.day for 2.5 yr. During the first 6 months, there were comparable and significant increases in height velocity SD score for chronological age with both doses (P < 0.001). However, during the ensuing 2 yr, the higher GH dose induced a significantly greater improvement in height velocity SD score for chronological age than 2 IU GH. Catch-up growth was only sustained for 2.5 yr with 4 IU. In contrast, catch-up growth ceased after 6 months with 2 IU. Neither 2 nor 4 IU GH resulted in accelerated bone maturation during 2.5 yr of therapy. There was a significant increase in plasma insulin-like growth factor-I (IGF-I) levels with either dose, but significantly more so with 4 IU. Plasma IGF-II levels only increased significantly with 4 IU. The pretreatment elevation of IGF-binding protein-1 (IGFBP-1) levels decreased by 50% during the first study year with the higher GH dose, whereas there was no decrease with 2 IU. The elevated pretreatment IGFBP-3 levels increased comparably and significantly with either GH dose. Interestingly, only 4 IU resulted in a significantly greater increase in IGF-I than in IGFBP-3 levels. Regardless of GH dose, there was an insignificant decrease in fructosamine levels, whereas lipid and parathyroid concentrations remained constant. Renal function deterioration did not accelerate. GH therapy with 4 IU/m2.day induced and maintained catch-up growth during 2.5 yr in children with CRI without evidence of adverse effects. Bone maturation did not accelerate. This suggests that this higher GH dose may be beneficial for children with severe growth retardation secondary to CRI.

Adolescent↗
PubMed1994

Difference in biological effects between insulin-like growth factor binding protein 1 and 3.

Insulin-like growth factor binding proteins 1 and 3 are essentially known as regulators of IGF bioactivity. However, we previously showed that IGFBP-3 was able, in chick embryo fibroblast (CEF), to 100% inhibit DNA synthesis stimulated by calf serum, while the maximal inhibition found with IGFBP-1 was 60%, suggesting a difference between the two IGFBPs in their biological functions. Results of the present work agree with this assumption: (a) Recombinant human IGFBP-3, like rat IGFBP-3, was able to 100% inhibit DNA synthesis stimulation induced by human serum, while this stimulation was 75% decreased by IGFBP-1. However, the most striking difference was observed when the effects of the two IGFBPs were compared for stimulation induced by a serum growth factor (SGF) fraction depleted in IGFs. Stimulation induced by the SFG fraction was more significantly decreased (p < 0.001) by IGFBP-3 than by IGFBP-1. The mean percent inhibition +/- SEM was 67.1 +/- 2.5 in the presence of IGFBP-3 (200 ng/ml) and 29.3 +/- 2.7 and 34.2 +/- 4 in the presence of 200 and 400 ng/ml IGFBP-1 respectively. Inhibition by 200 ng/ml IGFBP-1 and inhibition by 6 ng/ml IGFBP-3 were additive. However, inhibition by IGFBP-3 and that by IGFBP-1 were no longer additive at high concentrations of IGFBP-3, which might thus replace IGFBP-1. (b) FGF stimulation of CEF was similarly inhibition (65% and 70%) by IGFBP-1 and IGFBP-3. (c) TGF beta stimulation of CEF was more strongly decreased by IGFBP-3 (90%) than by IGFB-1 (60%).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

[Growth, development and prediction of body height in children with central precocious puberty after 3 years of therapy with Decapeptyl-Depot, a slow-releasing GnRH agonist].

More than 100 patients with central precocious puberty are participating in this international multicenter study using monthly i.m. injections of the slow-release GnRH agonist Decapeptyl-Depot. In 15 patients, Decapeptyl-Depot treatment could be discontinued after 2 years of therapy. Gonadal suppression was promptly reversible in all of them, as shown by prepubertal low gonadotrophin and sex steroid levels. Of the remaining 90 patients, 40 have been treated for more than 3 years, including 33 girls and 7 boys. Plasma levels of LH, FSH, estradiol and testosterone dropped to the prepubertal range after one month of Decapeptyl-Depot and remained there for the whole period of therapy. At start of therapy, mean chronologic age of these 40 children was 6.6 +/- 1.4 (SD) years, mean bone age 10.2 +/- 1.9 years. Mean predicted adult height increased in the boys from 173.6 +/- 13.8 (SD) cm at start of therapy to 184.6 +/- 17.0 cm after 3 years. Predicted adult height increased in girls from 158.0 +/- 12.2 to 161.0 +/- 7.5 cm. Undue side effects were not seen, long term tolerance was good. It is concluded that Decapeptyl-Depot injected i.m. every 4 weeks suppresses the pituitary gonadal axis in children with central precocious puberty without clinical or biochemical escapes, and leads to an increase in predicted adult height by more than 3 cm in all boys and in 53% of the girls after three years of treatment.

Body Height↗
PubMed1993

Insulin-like growth factor binding protein-2, 28 kDa and 24 kDa insulin-like growth factor binding protein levels are decreased in fluid of dominant follicles, obtained from normal and polycystic ovaries.

In order to investigate potential changes in insulin-like growth factor binding proteins (IGFBPs) during human follicle maturation, we examined the IGFBP profiles in follicular fluid from follicles in different stages of maturation. Samples were obtained from ovaries of women with regular menstrual cycles and of subjects with cycle abnormalities and polycystic ovaries (diagnosed as polycystic ovary syndrome (PCOS)) and analyzed by Western ligand blotting. IGFBPs of 43 kDa, 37 kDa, 31 kDa, a doublet around 28 kDa and a minor band of 24 kDa were detected in follicle fluid of normal non-dominant (size < 10 mm) and atretic (androstenedione/estradiol ratio > 4) follicles of both regularly menstruating women and PCOS patients. The 43 and 37 kDa IGFBPs could be identified as IGFBP-3 and the 31 kDa IGFBP as IGFBP-2, whereas the 28 kDa IGFBP could not be identified as IGFBP-1, all by immunoblotting techniques. A dramatic decrease in IGFBP-2, the 28 kDa and 24 kDa IGFBPs was observed in follicular fluid of dominant follicles (size > 10 mm) of both regular menstruating individuals and one PCOS patient as compared with follicular fluid of normal non-dominant or atretic follicles. These observations indicate that the PCOS follicle may not be different from normal with respect to IGFBP profiles. Furthermore, these results suggest that at least one of these IGFBPs might be involved in human folliculogenesis.

Adult↗
PubMed1993

Gene expression of the IGF binding proteins during post-implantation embryogenesis of the mouse; comparison with the expression of IGF-I and -II and their receptors in rodent and human.

The IGF binding proteins (IGFBPs) comprise at least six distinct species which may modulate the action of IGFs. IGFs are important regulators of fetal growth and differentiation. We have studied the mRNA expression of the six IGFBPs during post-implantation embryogenesis (day 11-18) by in situ hybridization techniques. Expression of IGFBP-1 was detected in mouse conceptuses after day 12 of gestation and seemed restricted to the liver. Transcripts for IGFBP-2, -4 and -5 were detected in various tissues and were found in all stages tested. In contrast, expression of IGFBP-3 and -6 could be detected only weakly in late gestational embryos. Comparison of the expression pattern of IGFBP-2, -4 and -5, which were found widely distributed in mouse conceptuses, revealed that IGFBP-2 was expressed mainly in the ectodermal layer and also in the mesoderm derived part of the tongue (day 13.5). Transcripts for IGFBP-4 however, only were detected in the mesoderm derived tissues, whereas expression of IGFBP-5 was restricted to the ectodermal layer. A similar distribution pattern was observed in the lung. In general, expression of IGFBP-2 and -5 was detected in the same cells, whereas IGFBP-4 and -5 were expressed mainly in different cell types. In rodents as in the human there is widespread expression of the genes coding IGFs, the IGFBPs and the receptors during pre- and postimplantation embryogenesis. These data support the assumption that the IGFs play an important role during embryogenesis.

Animals↗
PubMed1993

Cosegregation of missense mutations of the luteinizing hormone receptor gene with familial male-limited precocious puberty.

Familial male-limited precocious puberty is a male-limited autosomal dominant condition. It is characterized by increased testosterone synthesis in the absence of testicular stimulation by luteinizing hormone (LH). We hypothesised that an abnormal configuration of the LH receptor might autonomously activate G protein coupling, and thereby cause the overproduction of testosterone in this condition. To test this hypothesis, we screened for mutations in a part of the LH receptor gene that is important for G protein binding. DNA sequence variation was detected in 2 out of 5 families with male-limited precocious puberty by the single strand conformation polymorphism technique. Direct sequencing demonstrated different single nucleotide substitutions in the sixth transmembrane region of the LH receptor gene. The mutations cosegregated with the disorder in both families (lod score 5.76 without recombination). Both mutations cause an amino acid substitution in the sixth transmembrane domain, close to the C-terminal portion of the third cytoplasmatic loop, a region which is important for the binding of G proteins. We conclude that familial male-limited precocious puberty cosegregates with missense mutations in the LH receptor gene. These findings support the hypothesis that increased activity of the LH receptor is the pathogenetic mechanism that causes the abnormal pubertal development in this condition.

Amino Acid Sequence↗