Search

We describe a patient with pseudopseudohypoparathyroidism who had an osseous tubercle on the anterolateral margin of the foramen magnum causing compression of the spinal cord. This patient had no evidence for any endocrinopathies and had no other spinal canal anomalies. We suggest that the morphologic phenotype found in patients with pseudopseudohypoparathyroidism, also known as Albright's hereditary osteodystrophy, has an associated risk for spinal cord compression due to congenital vertebral anomalies. The poor recovery of neurologic function following spinal decompression mandates prompt recognition and therapy of this condition in patients with Albright's hereditary osteodystrophy. [ABSTRACT FROM AUTHOR]

The influence of chronically administered host-targeted drugs on the gut microbiome remains less understood compared to antibiotics. We investigated repetitive exposure effects of three common antiseizure medications [carbamazepine (CBZ), valproic acid, and levetiracetam] on the gut microbial composition, resistome, and metabolome using microcosms constructed from feces of young children. Microcosms were established by cultivating feces for 24 h (C0). These microcosms were daily transferred into fresh media for seven cycles (C1-C7) with antiseizure medications or carrier molecules, followed by four cycles without any drugs (C8-C11). The microbial dynamics and resistome of microcosms at C0, C1, C7, and C11 were assessed with 16S ribosomal ribonucleic acid gene sequencing or shotgun metagenome sequencing and real-time quantitative polymerase chain reaction analysis of the antimicrobial resistance genes, respectively. Metabolites of CBZ-treated and control microcosms at C0, C1, and C7 were evaluated using non-targeted metabolomics. Our findings revealed that the serial transfer approach longitudinally altered the microcosm composition. Among the medications, CBZ had the most substantial impact on the structure and metabolism of the feces-derived microcosms. The microbiome composition partially recovered during the drug-free period. Specifically, Bacteroides and Flavonifractor were depleted and Escherichia and Clostridium were enriched. Additionally, repetitive CBZ exposure increased the abundance and expression of genes related to various antibiotic resistance mechanisms, more specifically, efflux pumps and antibiotic target alteration. CBZ-induced changes in the microbiome were mirrored in the metabolome, with reductions in the citric acid cycle metabolites, glutamine, and spermidine, alongside increased levels of vitamin B6. Our study suggests that repetitive CBZ exposure may negatively impact gut microbial homeostasis and metabolism., Competing Interests: None declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of the International Society for Microbial Ecology.)

Recently, a unique Pro250Arg point mutation in fibroblast growth factor receptor 3 (FGFR3) was reported in 61 individuals with coronal craniosynostosis from 20 unrelated families [Muenke et al. (1997): Am J Hum Genet 60:555-564]. The discovery of this apparently common mutation has resulted in the definition of a recognizable syndrome, through analysis of subtle clinical findings in families who were previously thought to have a variety of other craniosynostosis syndromes. Previous diagnoses in some of these families have included Jackson-Weiss, Saethre-Chotzen, and Pfeiffer syndromes, as well as Adelaide-type craniosynostosis and brachydactyly-craniosynostosis syndrome [Adès et al. (1994): Am J Med Genet 51:121-130; von Gernet et al. (1996): Am J Med Genet 63:177-184; Reardon et al. (1997): J Med Genet 34:632-636; Bellus et al. (1996): Nat Genet 14:174-176; Hollaway et al. (1995): Hum Mol Genet 4:681-683; Glass et al. (1994): Clin Dysmorphol 3:215-223]. There appears to be a need to further delineate the phenotype associated with this common mutation in FGFR3. We compare the clinical characteristics of previously reported cases of this unique Pro250Arg mutation with those of two additional families and suggest that this syndrome with a unique mutational basis be designated coronal craniosynostosis with brachydactyly and carpal/tarsal coalition due to Pro250Arg mutation in FGFR3 gene, to emphasize the distinctive findings which may be present even in the absence of coronal craniosynostosis.

While loss-of-function mutations in Gsalpha are invariably associated with the short stature and brachydactyly of Albright hereditary osteodystrophy (AHO), the association with hormone resistance (to parathyroid hormone and thyrotropin) typical of pseudohypoparathyroidism type Ia (PHP-Ia) is much more variable. Observational studies and DNA polymorphism analysis suggest that maternal transmission of the Gsalpha mutation may be required for full expression of clinical hormone resistance. To test this hypothesis, we studied transmission of a frameshift mutation in Gsalpha through three generations of a pedigree affected by AHO and PHP-Ia. While all family members carrying this loss-of-function mutation in one Gsalpha allele had AHO, neither the presence of the mutation nor the degree of reduction of erythrocyte Gsalpha bioactivity allowed prediction of phenotype (AHO alone versus AHO and PHP-Ia). Paternal transmission of the mutation (from the patriarch of the first generation to three members of the second generation) was not associated with concurrent PHP-Ia, but maternal transmission (from two women in the second generation to four children in the third generation) was invariably associated with PHP-Ia. No expansion of an upstream short CCG nucleotide repeat region was detected, nor was there evidence of uniparental disomy by polymorphism analysis. This report, the first to document the effects across three generations of both paternal and maternal transmission of a specific Gsalpha mutation, strongly supports the hypothesis that a maternal factor determines full expression of Gsalpha dysfunction as PHP-Ia.

The activation of cell-surface receptors usually produces a transient increase of the extracellular acidification rate in culture cells that can be detected with a biosensor-based instrument. We describe here the application of this method in monitoring hormonal response of Galphas-deficient fibroblasts from patients with pseudohypoparathyroidism type Ia (PHP-Ia). We found that following exposure to isoproterenol, the mean acidification response of fibroblasts from four PHP-Ia patients was only 18% of the response in normal cells. In contrast, these two groups of fibroblasts had similar levels of response to insulin and dibutyryl cAMP. This is the first reported experimental evidence correlating reduced Galphas activity with diminished cellular responsiveness to hormones in cultured living cells. Our results also indicate that this approach will be useful for rapid screening of other metabolic diseases caused by abnormal cellular signaling.

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.

Defects in the G (guanine nucleotide-binding)-protein subunit (G alpha s) which stimulates adenylyl cyclase may result in either loss or gain of endocrine function. Reduced G alpha s activity is found in the hormone resistance syndrome, pseudohypoparathyroidism type Ia (PHP-Ia), while constitutive activation of G alpha s is associated with endocrine organ overactivity, including the gonadotropin-independent sexual precocity seen in patients with McCune-Albright syndrome. We identified two unrelated boys presenting with concurrent PHP-Ia and gonadotropin-independent sexual precocity (testotoxicosis). Mutational screening by denaturing gradient gel electrophoresis and sequencing of PCR-amplified exons of the G alpha s gene revealed a point mutation which generates an alanine-to-serine substitution in codon 366 of one G alpha s allele (A366S), an alanine present at the homologous position in all G-proteins. We have previously shown in transfected testis cells that the A366S mutation activates G alpha s by decreasing affinity for GDP, thereby increasing the rate of nucleotide exchange in a receptor-independent fashion. In contrast to differential stability of the activated mutant G alpha s protein in Leydig cells, with stability at 32 degrees C but not at 37 degrees C, skin fibroblasts with the mutation had the same reduced G alpha s levels at both temperatures. Our findings explain the limitation of clinical manifestations of G alpha s overactivity to testis, without involvement of other body appendages which are generally at lower than core body temperature. This unique mutation at a critically conserved residue of G alpha s is the first mutant G-protein which affects guanine nucleotide affinity and is associated with human disease, producing widely divergent and tissue-specific effects.

The basis for this study is two children with primary hyperparathyroidism (PHPT) who radiographically manifested both marked subperiosteal resorption and prominent osteosclerosis. We hypothesize that the parathyroid hormone (PTH) elevation not only increased osteoclastic resorption of cortical bone but also simultaneously enhanced cancellous bone formation, giving rise to osteosclerosis. In this report, we describe the changes in trabecular and cortical bone density, as measured by quantitative computed tomography (QCT), in these two young patients with severe PHPT, before and after removal of a parathyroid adenoma. Before surgery, the radiographic findings of subperiosteal resorption and osteosclerosis were associated with low cortical and high cancellous bone density values in both children. Within 1 week of surgery, both cortical and cancellous bone density values increased and serum concentrations of calcium and, to a lesser degree, phosphorus decreased due to the "hungry bone syndrome." Twelve weeks after parathyroidectomy, QCT bone density values and skeletal radiographs were normal in both patients. The findings suggest that in patients with severe PHPT, the catabolic effect of PTH on cortical bone may be associated with a simultaneous anabolic effect on cancellous bone, and PTH may cause a significant redistribution of bone mineral from cortical to cancellous bone.

Cardiac responsiveness to beta-adrenergic stimulation changes with age. Developmental changes in expression of guanine nucleotide-binding coupling protein (G protein) subunits may account for these physiologic changes. We measured steady-state levels of mRNA encoding the alpha-subunit of the specific G protein that stimulates adenylyl cyclase (Gs alpha) and three isoforms of beta-subunit of G proteins (G beta) in developing myocardium. Total RNA prepared from the right and left ventricles of fetal, neonatal, juvenile, and adult rabbits was size-fractionated, blotted, and probed with 32P-labeled cDNAs encoding rat Gs alpha, bovine G beta-1, human G beta-2, and human G beta-3. For standardization, these blots were subsequently hybridized with a 32P-labeled cDNA encoding glyceraldehyde 3-phosphate dehydrogenase (GAPD). Two-dimensional densitometric analysis of autoradiographs was used to quantify relative hybridization intensities. An age-dependent decrease in mRNAs encoding Gs alpha, G beta-1, and G beta-2 relative to mRNA encoding GAPD was observed in both ventricles, while G beta-3 mRNA was not detected. At all ages studied, levels of Gs alpha and G beta-1 mRNA were similar in the two ventricles. However, G beta-2 mRNA declined more in the left ventricle than in the right ventricle during maturation. Our results demonstrate developmental control in heart for mRNAs encoding several G protein subunits. In addition, differential declines in G beta-1 and G beta-2 mRNA in the right ventricle suggest that these G beta isoforms are regulated uniquely and may reflect functional roles for these G beta isoforms in different signaling cascades.

We investigated the effects of added beta gamma subunits of G proteins (G beta gamma) on beta-adrenergic responsiveness of transmembrane Ca2+ currents (ICa) in ventricular myocytes from neonatal rabbits. G beta 1 gamma 1 purified from retinal rods was dialyzed into cells via the voltage clamp micro-electrode. Stimulation of ICa by isoproterenol was not affected by added intracellular G beta 1 gamma 1 or by carbachol alone but was completely blocked by combined G beta 1 gamma 1 and carbachol. Pretreatment of cells with pertussis toxin or temporal separation of carbachol and isoproterenol allowed stimulation of ICa by isoproterenol in cells dialyzed with G beta 1 gamma 1. Carbachol and G beta 1 gamma 1 together also did not prevent stimulation of ICa by dibutyryl-cyclic AMP. Thus, rather than simply inactivating Gs alpha by mass action, G beta 1 gamma 1 acts in concert with carbachol to inhibit isoproterenol stimulation of ICa.

The HLA-B47,DR7 haplotype in congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency contains a deletion of most of the active CYP21 gene and the entire adjacent C4B gene. The C4A gene produces a protein which is electrophoretically C4A but antigenically C4B. In the Old Order Amish, the HLA-B47,DR7 haplotype contains no deletion, but is immunologically identical to the CAH haplotype in both areas flanking the crossover region. We compared some of the genes in the MHC Class II and Class III regions in the Amish and CAH-linked haplotypes to define further the relationships between the two. The complement factor B (Bf) proteins differed, but no Bf RFLPs were identified. The complement factor 2 genes exhibited different BamHI RFLPs. Analyses of the tumor necrosis factor-alpha genes revealed the same NcoI restriction patterns. The RD genes contained microsatellites of the same size. Portions of the MHC Class II DR and DQ, and Class III CYP21 and C4 alleles were sequenced. The exon 2 sequences of DQ2 and DR7 were identical in the two haplotypes. In the Amish haplotype, both CYP21 and C4 gene pairs were present and functionally normal. The CAH haplotype had two sequence crossovers: from CYP21P to CYP21 in the 7th intron, and from C4A to C4B between codons 1106 (exon 26) and 1157 (exon 28). A model is proposed which accounts for the CAH-linked mutant haplotype arising from a nonmutant homologue via three crossings-over.

The faster recovery of cardiac contractility in newborn rabbit hearts during acute acidosis compared to adult hearts correlates with greater cellular activity of the Na+/H+ exchanger. We quantified mRNA encoding Na+/H+ exchanger-1 (NHE-1) in rabbit ventricles of fetal (27 days gestation), newborn (2-5 days), and adult (> 6 months) New Zealand white rabbits using reverse transcription-polymerase chain reaction (RT-PCR) and RNase protection assay, with GAPD mRNA as standard. Both RT-PCR and RNase protection assay revealed similar (p > 0.05) cardiac levels of NHE-1 mRNA in fetal and newborn hearts, while NHE-1 mRNA in these hearts was 1.7x and 1.6x greater than in adult hearts by both RT-PCR and RNase protection assay. These developmental changes in NHE-1 mRNA correlate with the developmental changes in Na+/H+ activity in sarcolemmal vesicles purified from rabbit heart.

To study the effects of triiodothyronine (T3) on responsiveness of L-type calcium currents to beta-adrenergic stimulation in neonatal hearts, ventricular myocytes were isolated from neonatal rabbits and cultured in medium containing 10% fetal bovine serum to which T3 had been added to achieve either hypothyroid, euthyroid, or hyperthyroid conditions, as assessed by measurement of free T3 concentrations. During a 24-h culture period, the striated rod-shaped myocardial cells progressively assumed a stellate shape with reduced surface area; however, the rate constants for diffusion of Na+ from a microelectrode pipette into the cells remained unchanged. Voltage-dependent characteristics of L-type calcium currents as assessed by whole-cell voltage clamp studies were also unchanged after culture with various concentrations of free T3. By contrast, the stimulation of voltage-gated transmembrane calcium current from baseline by isoproterenol was reduced (p < 0.05) in hypothyroid cells (15 +/- 8%; n = 14) compared with either euthyroid (86 +/- 15%; n = 18), hyperthyroid (54 +/- 16%; n = 12) or freshly isolated (50 +/- 12%; n = 10) myocytes. The differences in beta-adrenergic responsiveness of voltage-gated transmembrane calcium current to isoproterenol between euthyroid, hyperthyroid, and freshly isolated cells were not significant (p > 0.05). These results indicate that retention of beta-adrenergic responsiveness of voltage-gated transmembrane calcium current in neonatal cardiac myocytes depends on physiologic amounts of active thyroid hormone. Our culture method for neonatal cardiac myocytes will be useful for studying physiologic modulation of beta-adrenergic responsiveness.

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)

Luteinizing hormone stimulates testicular Leydig cells to produce testosterone by binding to a receptor that activates the G protein Gs and adenylyl cyclase. Testotoxicosis is a form of precocious puberty in which the Leydig cells secrete testosterone in the absence of luteinizing hormone, often due to constitutive activation of the luteinizing hormone receptor and (indirectly) Gs (refs 1-4). Here we study two unrelated boys suffering from a paradoxical combination of testotoxicosis and pseudohypoparathyroidism type Ia (PHP-Ia), a condition marked by resistance to hormones acting through cyclic AMP (parathyroid hormone and thyroid-stimulating hormone) as well as a 50% decrease in erythrocyte Gs activity (the remaining 50% is due to the normal Gs allele). In both patients, a mutation in the gene encoding the Gs alpha-subunit replace alanine at position 366 with serine. We show that this alpha s-A366S mutation constitutively activates adenylyl cyclase in vitro, causing hormone-independent cAMP accumulation when expressed in cultured cells, and accounting for the testotoxicosis phenotype (as cAMP stimulates testosterone secretion). Although alpha s-A366S is quite stable at testis temperature, it is rapidly degraded at 37 degrees C explaining the PHP-Ia phenotype caused by loss of Gs activity. In vitro experiments indicate that accelerated release of GDP causes both the constitutive activity and the thermolability of alpha s-A366S.

Eight children with growth failure following renal transplant have been selected for recombinant human growth hormone (rhGH) treatment at Children's Hospital using the following criteria: (1) a functioning allograft for at least one year; (2) height < third percentile; (3) growth velocity < 4 cm/year; (4) growth potential; and (5) low-dose alternate-day glucocorticoid dosing. The children were 7.4 to 17.7 years of age; had received transplants 2.6 to 12.3 years before rhGH treatment; and all had decreased allograft function. The growth velocity of these children increased from 1.7 +/- 0.7 to 7.1 +/- 2.1 cm/year during the first year of rhGH treatment (0.05 mg/kg s.c. daily). The mean height SD score improved -3.9 +/- 1.5 to -3.4 +/- 1.3 in the seven children who completed one year of treatment (P < 0.001). There was no change in glucose tolerance during rhGH treatment. The serum creatinine concentration increased in all patients with a concomitant decrease in creatinine clearance. The mean rate of change in the inverse creatinine (1/Cr) increased from -0.005 +/- 0.004 dl/mg/month in the two years prior to rhGH treatment to -0.023 +/- 0.015 dl/mg/month during rhGH treatment (P < 0.01). The relative risks and benefits of rhGH treatment must be carefully considered for each patient.

A 17-year-old boy with Kallmann syndrome had complex congenital heart disease that included double-outlet right ventricle, d-mal-position of the great arteries, right aortic arch, and hypoplastic main pulmonary artery. He had neurosensory hearing loss and mental retardation. The 7 previously reported patients with Kallmann syndrome and cardiac abnormalities were short with height > or = 2 standard deviations below the mean for age (5/7), lacked a family history of Kallmann syndrome (6/6), and were mentally retarded (4/4). Patients presenting with Kallmann syndrome and congenital heart defects appear to represent a distinct subgroup of patients with Kallmann syndrome. The cause of this association is unclear, but may involve either autosomal recessive inheritance, sporadic dominant mutation, or a shared teratogenic event during the first trimester of gestation.

Pseudohypoparathyroidism type Ia (PHP-Ia), an inherited multi-hormone resistance syndrome, is associated with deficient cellular activity of the alpha-subunit of the guanine nucleotide-binding protein (Gs alpha) that stimulates adenylyl cyclase. We determined prevalence of three recently described mutations in exons 1 and 10 of the Gs alpha gene among 24 unrelated patients with PHP-Ia. Restriction analysis was used to detect two mutations that produce unique RFLPs, and allele-specific oligonucleotide hybridization was used to detect the other mutation. As none of these mutations were not found, genomic DNA was analyzed with denaturing gradient gel electrophoresis to screen for other mutations in exon 10. Mutations of the initiation codon and exon 10 in the Gs alpha gene thus rarely (< or = 4% each) cause PHP-Ia and the Gs alpha gene mutations causing PHP-Ia are heterogeneous and unique to each pedigree.

To determine the usefulness of growth hormone treatment among children with renal allografts, we treated nine children with functioning renal transplants who were less than 16 years of age and had poor growth. The nine children, who were aged 12.6 +/- 4.0 years, had (1) heights greater than 2.5 SD less than the mean for age, (2) growth rates less than or equal to 5 cm/yr, and (3) additional growth potential, as assessed by bone age (8.9 +/- 2.8 year). Insulin-like growth factor I, thyrotropin, and thyroid hormone levels were normal for age in all children. Growth hormone treatment increased growth rates from 1.9 +/- 1.1 cm/yr to 7.2 +/- 1.8 cm/yr without accelerating skeletal maturation and without advancing pubertal status. During growth hormone treatment, serum creatinine concentration rose from 140 +/- 50 to 190 +/- 80 mumol/L (1.6 +/- 0.6 to 2.1 +/- 0.9 mg/dl) (p less than 0.05), and creatinine clearances decreased from 0.79 +/- 0.37 to 0.58 +/- 0.30 ml/sec per 1.73 m2 (47 +/- 22 to 35 +/- 18 ml/min per 1.73 m2) (p less than 0.05) but then remained stable. Growth rates of two patients returned to pretreatment rates when growth hormone treatment was discontinued after 5 and 7 months because of increased serum creatinine values. Growth hormone treatment may be useful as adjunctive therapy for increasing growth rates in selected children with renal allografts who have poor growth; however, serum creatinine concentrations should be closely monitored during such treatment.

We performed oral glucose tolerance tests (oGTTs) on 15 children who had functioning renal allografts received greater than or equal to 18 months previously, had adequate renal function, and had heights greater than 2.5 SD below the mean height for age. Three of the children had impaired glucose tolerance; their mean glucose levels during the last 2 hours of the oGTT were higher (p less than 0.05) than published control values. Integrated glucose concentrations correlated inversely with the prednisone dose on the first day of an alternate-day dosage schedule (R2 = 0.383) and directly with adiposity (partial R2 = 0.322). The integrated insulin concentration correlated directly with the prednisone dose on day 1 of an alternate-day regimen (R2 = 0.355) and with age (partial R2 = 0.163). In 10 children with renal transplants who had been treated with growth hormone for greater than or equal to 6 months, the mean fasting glucose concentration, integrated glucose concentration, and integrated insulin concentration during the oGTTs obtained after 6 months or 12 months of growth hormone treatment were not significantly different (p greater than 0.05) from values measured before the treatment. We conclude that increased integrated concentrations of both glucose and insulin during oGTTs in children with renal allografts correlate with the dose of prednisone administered on the first day of an alternate-day schedule, with age, and with adiposity index. Growth hormone treatment of children with renal allografts who are growing poorly does not significantly affect glucose metabolism as assessed by oGTT.

Human hearts with idiopathic dilated cardiomyopathy have diminished adenylate cyclase activity and increased amounts of the alpha-subunit of the inhibitory guanine nucleotide-binding regulatory protein (alpha Gi) as measured by pertussis toxin catalyzed ADP-ribosylation. We utilized specific antisera against synthetic peptides corresponding to amino sequences deduced from cDNA's encoding the three alpha Gi subspecies to compare the immunologic and bioactivity levels of Gi in failing and non-failing human hearts. The various antisera detected three peptides with Mr 42,000, 38,000, and 37,000. Only the Mr 42,000 peptide co-migrated with the pertussis toxin substrate. Although functional activity of alpha Gi was increased in the particulate fractions of the failing heart as measured by inhibition of guanine nucleotide-stimulated adenylate cyclase activity and the quantity of pertussis toxin substrate was also increased, there were not associated changes in the levels of immunodetectable Gi. Therefore, the increased functional activity of Gi in the failing human heart as assessed by adenylate cyclase measurements cannot be explained by a relative increase in the among of Gi protein.

Some children do not grow well following successful renal transplantation. We reviewed 25 children with renal allografts who receive regular medical care in the renal transplant program at The Children's Hospital, were less than or equal to 18 years of age, and had stable renal function. We compared children who were growing well (n = 14) with those who were growing poorly (n = 11). The children with poor growth more frequently had elevated serum creatinine concentrations (8/11 vs. 3/14). The mean age at transplantation was the same, although the duration of follow-up was shorter for the children growing well (3.3 +/- 0.5 years) than for those growing poorly (6.2 +/- 1.0 years, P less than 0.02). Eight of the children who were growing poorly underwent endocrinologic evaluation. Plasma growth hormone (GH) concentrations were measured during sleep, after arginine and L-DOPA administration, and during a 4-hr oral glucose tolerance test. In 4 patients, the maximum GH concentration was inadequate both following pharmacologic stimulation (4.0 +/- 2.6 ng/ml, n = 4) and during sleep (4.4 +/- 0.2 ng/ml, n = 3). In 2 additional patients, maximal GH concentrations were subnormal during sleep despite adequate responses during pharmacologic stimulation. In the final two patients, GH secretion was adequate both during sleep and after stimulation. All children studied had some degree of renal insufficiency with a mean creatinine clearance of 39 +/- 4 ml/min/1.73 m2. Plasma concentrations of thyroxine, thyrotropin, and IGF-I were normal for age in all eight patients. We conclude that abnormalities in GH secretion occur frequently among patients who grow poorly following successful renal transplantation. Evaluation of GH secretion may be useful in evaluating growth failure in this group of patients, and the usefulness of GH therapy should be investigated.

We have recently demonstrated that the activity of the inhibitory guanine nucleotide-binding regulatory protein Gi is increased in the hearts of patients with idiopathic dilated cardiomyopathy. We determined whether altered Gi protein levels in the failing human heart correlate with changes in steady state levels of the mRNA encoding one of the alpha Gi peptides. cDNAs encoding alpha Gs, alpha Go, and three subspecies of alpha Gi were used as hybridization probes to quantify steady state levels of mRNA encoding these alpha G peptides in failing and non-failing human heart. The lengths of the mRNAs that encode each alpha G peptide were the same in non-failing and failing hearts. Steady state levels of mRNA encoding both alpha Gi-3 and alpha Gs were significantly increased in the failing hearts when compared to non-failing hearts. By contrast, there was no significant change in the levels of mRNA encoding alpha Go or of rRNA. The relative abundance of the mRNA encoding each of the subspecies of alpha Gi was different in the human heart; alpha Gi-3 mRNA was abundant, alpha Gi-2 was barely detectable, and we were not able to detect alpha Gi-1 utilizing our hybridization conditions. These results suggest that alterations at the level of transcription as well as post-translational modifications can affect the activities of transmembrane signaling proteins in chronic congestive heart failure.

We found both renal resistance to endogenous and exogenous PTH and reduced activity of the stimulatory guanine nucleotide-binding regulatory protein (Ns) of adenylate cyclase in a man with clinical signs of pseudohypoparathyroidism type Ia (PHP-Ia). Both of his children also had reduced Ns levels and short stature. The girl, 11 yr old, had evidence of partial resistance to PTH, while the son, age 7 yr, had no apparent abnormalities in calcium metabolism or response to administered PTH. Variable expression of the metabolic abnormalities of PHP during childhood has been previously described. The occurrence of reduced Ns activity in father and son is consistent with autosomal dominant inheritance for the primary biochemical defect of PHP-Ia in this family.