A novel mutation at the donor splice site of intron 3 of the GH-I gene in a patient with isolated growth hormone deficiency

A G - C transversion at the fifth nucleotide of intron 3 of GH-I gene was identified in a sporadic case of isolated growth hormone deficiency (IGHD). The mutation was absent in both of the parents, indicating that the mutation occurred de novo. An abnormal hGH mRNA lacking a region encoded by exon 3 was spliced when the mutant GH-I gene was expressed in cultured cells. Since skipping of exon 3 is a common feature for four different mutant GH-I genes identified in patients with autosomal dominantly inherited IGHD, we conclude that the mutation causes IGHD in this case.     

A patient with pseudohypoaldosteronism type II caused by a novel mutation in WNK4 gene

Pseudohypoaldosteronism Type II (PHAII) is a very rare disorder characterized by hyperkalemia, hypertension, and slight hyper-chloremic metabolic acidosis. The index patient showed typical features of PHAII, including elevated blood pressure (140–150/90–100 mmHg), hyperkalemia in the range of 5.30–5.60 mmol/l (normal range is 3.50–5.10 mmol/l), accompanied by hyperchloremia of 109.5–112.0 mmol/l (normal 95.0–108.0 mmol/l) and acidosis with bicarbonate levels of 19.5–20.1 mmol/l (normal 22.0–27.0), GFR was 98.95 ml/min (normal > 90). However, these features were absent in his parents. Sequencing analysis found the patient with a WNK4 gene mutation, 1682 C > T in Exon 7, which resulted a missense mutation at codon 561 (P561L). The variation in codon 561 was not found in his parents and 100 unrelated control subjects. The identified WNK4 mutation which has not been described previously is the probable cause of PHAII.     

Reduced serum insulin-like growth factor-1 (IGF-1) and IGF-binding protein-3 levels in adults with inflammatory bowel disease

In the present study, the changes in circulating IGF-1 and its binding protein IGFBP-3 were determined in adult patients with active inflammatory bowel disease (IBD) in order to assess the effect of this inflammatory condition on the IGF system. IGF-1 and IGFBP-3, as well as interleukin-6 (IL-6) were measured in serum obtained from 22 consecutive newly diagnosed patients (mean age 41.3 years) with active IBD, including 10 patients with Crohn's disease (CD), and 12 with ulcerative colitis (UC). For comparison the same parameters were determined in 30 healthy volunteers matched for age, sex and Body Mass Index (BMI). Serum IGF-1 and IGFBP-3 levels were similar in the two subgroups of patients and the values from all patients were combined for comparison with those from the control group. The mean (+/- SD) serum IGF-1 concentration (178 +/- 91 ng/ml) in the patients with IBD was lower compared with that in the controls (227 +/- 79 ng/ml, P<0.035). Similarly, the mean IGFBP-3 concentration in the patients was lower than in the controls (1.6 +/- 0.6 ng/ml vs 3.2 +/- 0.7 ng/ml respectively, P<0.001), Serum IL-6 levels were higher in the patients compared with the controls (5.5 +/- 4.2 vs 0.65 +/- 0.11 pg/ml, P<0.0001). The reduced IGF-1 and IGFBP-3 levels in patients with active IBD suggest that this systemic inflammatory condition is associated with a degree of acquired GH resistance, possibly induced by inflammatory cytokines.     

A novel variant in Serpina7 gene in a family with thyroxine-binding globulin deficiency

Thyroxine-binding globulin (TBG) carries approximately 75% of serum T4 and T3. This protein is encoded by serpina7 gene, formerly known as TBG gene, localized on X-chromosome (Xq22.2). A deficiency in TBG is suspected when abnormally low serum total T4 and T3 are encountered in clinically euthyroid subjects in the presence of normal serum TSH. This condition has been associated with different serpina7 gene mutations resulting in amino acid substitutions or truncations in the mature protein. Herein, we report a new serpina7 gene variant in three members of the same family. It results in the replacement of the normal asparagine 233 by isoleucine and, subsequently, in disruption of a glycosylation site. Co-segregation of this new variant with undetectable levels of TBG in the hemizygous man studied and failure to recognize the same variant in 100 alleles at random, made us to consider it as the underlying cause of the TBG deficiency.     

Association of APOE-C1 gene cluster polymorphisms with gallstone disease

BACKGROUND: Genetic polymorphisms in apolipoprotein genes may be associated with alteration in lipid profile and susceptibility to gallstone disease. AIM: To find out the association of APOE HhaI and APOC1 HpaI polymorphisms with gallstone disease. SUBJECTS: HhaI polymorphism of APOE and HpaI polymorphism of APOC1 were analysed in DNA samples of 214 gallstone patients and 322 age- and sex-matched healthy controls. METHODS: For genotyping DNA samples of all study subjects were amplified using polymerase chain reaction, followed by restriction digestion. All statistical analyses were done using SPSS v11.5 and ARLEQUIN v2.0 softwares. RESULT: APOC1 HpaI polymorphism was found to be significantly associated with gallstone disease. Frequency of H2H2 was significantly higher (P = 0.017) in patients than in controls and it was imposing very high risk (OR 9.416, 95% CI 1.125-78.786) for gallstone disease. When data were stratified in male and female, H2H2 was associated (P = 0.011) with disease in females only. Analysis at allele level revealed no association. APOE HhaI polymorphism and APOE-C1 haplotypes showed no association with gallstone disease. CONCLUSION: APOC1 HpaI polymorphism is associated with gallstone disease and shows gender-specific differences. APOE HhaI polymorphism may not be associated with gallstone disease.     

A novel mutation in the G4.5 (TAZ) gene in a Greek patient with Barth syndrome

Barth Syndrome (BTHS) is a rare X-linked recessive inborn error of metabolism, which is characterized by dilated cardiomyopathy, neutropenia, skeletal myopathy and short stature. Barth Syndrome is associated with mutations in the tafazzin (TAZ) gene at Xq28 that result in cardiolipin deficiency and abnormal mitochondria. Here we report a 5.5-month old boy with BTHS phenotype who carries a novel missense T43P mutation in exon 2 of the TAZ gene.     

Maternal nutrition affects the ability of treatment with IGF-I and IGF-II to increase growth of the placenta and fetus, in guinea pigs

The aim of this study was to investigate how administration of IGF-I and IGF-II, during early to mid pregnancy, affects maternal growth and body composition as well as fetal and placental growth, in ad libitum fed, and in moderately, chronically food restricted guinea pigs. From day 20 of gestation, mothers (3-4 months old) were infused with IGF-I, IGF-II (565 microg/day) or vehicle for 17 days and then killed on day 40 of gestation. Maternal organ weights, fetal and placental weights were assessed. Treatment with IGFs did not alter body weight gain and had small effects on body composition in the mothers. Both IGF-I and IGF-II increased fetal and placental weights in ad libitum fed dams and IGF-I increased placental weight in food restricted dams. In conclusion, treatment with IGF-I during the first half of pregnancy stimulates placental growth in both ad libitum fed and food restricted guinea pigs without affecting maternal growth while fetal growth is stimulated by IGF treatment only in ad libitum fed animals.     

A novel germline mutation of the LKB1 gene in a patient with Peutz-Jeghers syndrome with early-onset gastric cancer

The gene responsible for Peutz-Jeghers syndrome (PJS), LKB1 (also called STK11) was mapped to chromosome 19p13.3 and was found to encode a putative serine/threonine protein kinase, LKB1. As only a limited number (100) of germline mutations of the gene have been reported, and because the protein function is still unclear, information about LKB1 mutations and their expression should be accumulated to understand the phenotype-genotype correlation of this disease. Here we report a patient with sporadic PJS with early-onset gastric cancer. We found a novel germline frameshift mutation (757-758insT) in the LKB1 gene and a marked reduction in LKB1 protein expression in the carcinoma cells, suggesting that the loss of LKB1 function may have led to the carcinogenesis of the gastric cancer.     

Regulation of protein secretion into bile: Studies in mice with a disrupted mdr2 p-glycoprotein gene

Protein is secreted into bile via several independent pathways. The aim of this study was to investigate whether these pathways are influenced by secretion of biliary lipid. Protein secretion and biliary lipid output were studied in wildtype mice (+/+), heterozygotes (+/−), and homozygotes (−/−) for mdr2 gene disruption. Biliary lipid and protein output were varied by infusion with taurocholate (TC) and tauroursodeoxycholate (TUDC). Exocytosis and transcytosis were unaltered in (−/−) mice. Infusion with TC strongly induced secretion of alkaline phosphatase in (−/−) mice but had little effect in (+/−) and (+/+) mice. Infusion with TUDC had little effect on alkaline phosphatase output. In contrast, both TUDC and TC strongly stimulated secretion of aminopeptidase N and lysosomal enzymes in (+/+) mice but had no effect in (−/−) animals. Aminopeptidase N secretion correlated with phospholipid output, but only at high flux. At low flux, aminopeptidase N was secreted independently from both phospholipid and bile salts. The canalicular membrane enzymes alkaline phosphatase and aminopeptidase N are secreted via separate pathways. Part of alkaline phosphatase output is controlled by bile salt hydrophobicity, whereas at high lipid flux, aminopeptidase N secretion seems to be coupled to phospholipid output. Lysosomal enzymes follow the latter pathway.     

Hansenula anomala killer toxin induces secretion and severe acute injury in the rat intestine

The yeast Hansenula anomala has been associated with gastrointestinal symptomatology and damage to the intestinal wall in humans. In vitro and in vivo, H. anomala secretes a toxin, killer toxin, which is lethal to other microorganisms. In view of the very high rate of killer phenotype expression recorded for H. anomala strains in nature, this study aimed to investigate the hypothesis that H. anomala killer toxin plays a role in the pathogenesis of H. anomala-induced enteritis. Effects of active and heat-inactivated H. anomala killer toxin on intestinal fluid homeostasis and electrolyte balance were investigated in rat small intestine using a standard intestinal perfusion technique. Sections of the perfused jejunum tracts were examined histologically. H. anomala killer toxin induced a significant secretion of water and electrolytes. No significant change was observed when either heat-inactivated H. anomala killer toxin or control growth medium were tested. Histological analysis showed ischemic degeneration of villi and sloughing of surface epithelium in 50% of active H. anomala killer toxin-perfused jejuna. This paper presents original observations compatible with the hypothesis that H. anomala killer toxin plays a role in the pathogenesis of H. anomala-induced enteritis.     

Methylprednisolone does not inhibit the release of growth hormone after intravenous injection of a novel growth hormone secretagogue in rats

The present study was undertaken to study the growth hormone-releasing properties and growth-promoting effect of a GH secretagogue ipamorelin (IPA) in rats given the synthetic glucocorticoid methylprednisolone (MP).In a first experiment, rats received either saline or MP (5.0 mg/kg) for 8 days. Treatment with MP significantly (P< 0.001) decreased body weight gain, but the acute response to either IPA or growth hormone releasing hormone (GHRH) in terms of plasma GH was not changed.In a second experiment, venous catheters were surgically implanted. On the next day, rats were randomly allocated to receive saline alone, MP alone (5.0 mg/kg) or MP plus IPA in doses of 0.4 or 1.6 mg/kg/day for 10 days. IPA was administered intravenously four times a day.MP treatment significantly (P< 0.05) retarded recovery from surgery in terms of body weight. Thus, saline treated animals lost 4.0 +/- 3.5 g over the entire experimental period, whereas animals receiving MP lost 13. 6 +/- 2.9 g. When IPA was given together with MP, losses in body weight were significantly (P< 0.05) reduced to 2.3 +/- 2.0 and 1.6 +/- 2.0 g in animals given the high and low dose of IPA, respectively. In parallel with this IGF-I levels increased.In conclusion, this work shows that MP does not disrupt the response of the GH-IGF-I axis to an exogenous stimulus like IPA, and repeated stimulation leads to increases in IGF-I and of body weight gain.     

Effect of germfree state on the capacities of isolated rat colonocytes to metabolize n-Butyrate, glucose, and glutamine

Among substrates available to the colonic mucosa, n-butyrate from bacterial origin represents a major fuel. The present work investigated possible modifications of energy substrate metabolism in colonocytes isolated from germfree rats. Colonocytes isolated from germfree vs. conventional rats were incubated (30 minutes at 37°C) in the presence of ¹⁴C-labeled n-butyrate (10 mmol/L), glucose (5 mmol/L), or glutamine (5 mmol/L). ¹⁴CO₂ and metabolites generated were measured. Possible regulatory steps were also investigated. Glucose use rate was 25% lower in germfree rat colonocytes due to a reduced glycolytic capacity in these cells. Differences in 6-phosphofructo-1-kinase activity could account for this decrease. In contrast, glutamine use rate was 45% higher, and this was correlated with a higher maximum velocity of glutaminase in these cells. Nevertheless, the capacities to oxidize glucose and glutamine remained unchanged. Although the capacity to use n-butyrate was maintained in colonocytes of germfree rats, the ketogenic capacity was lower, whereas the capacity to oxidize n-butyrate was higher. The mitochondrial 3-hydroxy-3-methylglutaryl-coenzyme A synthase protein was identified in the colonic mucosa. Moreover, the messenger RNA and amount of protein were 75% lower in the germfree state. The absence of an intestinal microflora induces specific changes in the metabolic capacities of colonocytes.     

ABCB1 gene polymorphisms and haplotype analysis in colorectal cancer

Purpose  The aim of this study was to determine the significance of three most common single-nucleotide polymorphisms (SNPs) of ABCB1 gene in the development of colorectal cancer and to estimate the influence of these SNPs to surviving patients' treatment combination adjuvant therapy 5-fluorouracil/leucovorin. Haplotype structure of ABCB1 was analysed, and degree of linkage disequilibrium (LD) between SNPs of ABCB1 was estimated. Materials and methods  Tumour specimens of 95 patients with colorectal cancer and blood samples of 95 healthy cases were studied. Genotyping of ABCB1 gene was performed by automated sequencing or polymerase chain reaction-restriction fragment length polymorphism method. Comparison of frequencies of alleles/genotypes/haplotypes between the studied group (colorectal cancer samples) and the control group (blood samples) were analysed. These results were correlated with the surviving patients after treatment of adjuvant chemotherapy. Results  Significant differences in ABCB1 _1236C>T (p = 0.00043) and ABCB1 _2677G>T/A (p = 0.04) genotype distribution and T₁₂₃₆ allele distribution (CT₁₂₃₆ or TT₁₂₃₆ vs CC₁₂₃₆; p = 0.0499, OR = 0.55, Fi–Yule coefficient = 0.14) were found. A strong LD between ABCB1 _1236C>T and ABCB1 _2677G>T/A SNPs (D′ = 0.621, r ² = 0.318) was detected. All SNPs were located in one haplotype block. There were significant differences in haplotype distributions between colorectal cancer patients and healthy population (p = 0.03). Significant differences in survival probability of colorectal cancer patients' treatment chemotherapy according to allele of ABCB1 _3435C>T was observed. Survival probability of patients with wild-type C₃₄₃₅ allele were higher than among patients without this allele (p = 0.04572). Conclusions  These results suggested that three studied SNPs of ABCB1 were located in one haplotype block. Differences in ABCB1 _1236C>T and ABCB1 _2677G>T/A genotypes and T₁₂₃₆ allele distribution between investigated populations indicate significant impact of these SNPs on risk of development of colorectal cancer. Polymorphism ABCB1 _3435C>T may be a prediction marker of cancer chemotherapy effectiveness. Differences in haplotype distributions between colorectal cancer patients and healthy population suggested that other potential SNPs, especially in regulatory region of ABCB1 gene, may influence P-glycoprotein expression and function.     

Identification of a novel splicing mutation in the growth hormone (GH)-releasing hormone receptor gene in a Chinese family with pituitary dwarfism

A Chinese family with autosomal recessive pituitary dwarfism was identified and the proband was evaluated by MRI and hormonal analysis, which revealed pituitary dwarfism with a complete growth hormone deficiency. MRI showed a pituitary gland with a small anterior pituitary of 2.2 mm and evidence of hypoplastic pituitary. Linkage analysis with markers spanning 17 known genes for dwarfism revealed linkage of the family to the growth hormone-releasing hormone receptor (GHRHR) gene. Mutational analysis of all exons and exon–intron boundaries of GHRHR was carried out using direct DNA sequence analysis. A novel homozygosis mutation, a G to A transition located in the splice donor site at the beginning of intron 8 (IVS8+1G>A), was identified in the proband. The two other patients in the family are homozygous, whereas the living mother of the proband is heterozygous for the IVS8+1G>A mutation. The mutation was not found in 100 normal chromosomes from healthy Chinese individuals of Han nationality. An in vitro splicing assay using HeLa cells transfected with expression vectors containing the normal or the mutant GHRHR minigenes consisting of genomic fragments spanning exons 7–9 showed that the IVS8+1G>A mutation caused abnormal splicing, which is predicted to give rise to truncation or frameshift, leading to severely truncated GHRHR proteins. These results provide strong evidence that the splicing mutation IVS8+1G>A of GHRHR is a cause of pituitary dwarfism in the Chinese family.     

Coexpression of 5-HT2A and 5-HT4 receptors coupled to distinct signaling pathways in human intestinal muscle cells

The type and function of 5-hydroxytryptamine (5-HT) receptors on intestinal muscle cells in humans are not known. 5-HT receptors were characterized pharmacologically and by radioligand binding. Contraction, relaxation, inositol 1,4,5-triphosphate (IP₃) and adenosine 3′,5′-cyclic monophosphate (cAMP) formation, and 5-HT binding were measured in dispersed muscle cells and in cells in which only one receptor type was preserved by selective receptor protection. 5-HT binding was completely inhibited by 5-HT and partially by 5-HT_2A (ketanserin), 5-HT₄ (SDZ-205,557), and 5-HT_1p (N-acetyl-5-hydroxytryptophyl-5-hydroxytryptophan amide; 5-HTP-DP) receptor antagonists. 5-HT caused contraction that was inhibited by ketanserin and augmented by SDZ-205,557 and 5-HTP-DP. In the presence of ketanserin, 5-HT caused relaxation of cholecystokinin-contracted cells that was inhibited by SDZ-205,557 and 5-HTP-DP. 5-HT increased IP₃, which was inhibited by ketanserin, and cAMP, which was inhibited by SDZ-205,557 and 5-HTP-DP. In cells with only 5-HT_2A receptors, 5-HT caused contraction only, and residual binding was inhibited by ketanserin. In cells with only receptors, 5-HT caused only relaxation and residual binding was inhibited by SDZ-205,557 and 5-HTP-DP. 5-HT_2A receptors mediating contraction and 5-HT₄ receptors mediating relaxation coexist on human intestinal muscle cells. The 5-HT₄ receptors are closely similar or identical to 5-HT_1p receptors.     

A novel KCNH2 mutation as a modifier for short QT interval

In a 34-year-old man showing short QT interval (QTc 329 ms), we identified a novel C-terminal KCNH2 mutation, R1135H. Using a heterologous expression system with CHO cells, the mutant channels were found to display a significantly slow deactivation, which resulted in a gain-of-function for reconstituted ‘I_Kr’ channels. This mutation could modify clinical phenotypes for this patient.     

Low-density lipoprotein receptor-related protein-associated protein (LRPAP1) gene IVS5 insertion/deletion polymorphism is not a risk factor for gallstone disease in a Polish population

BACKGROUND: There is growing evidence that gallstone formation may be genetically determined. It was recently presented that a common polymorphism in the LRPAP1 gene might be associated with gallstone disease. AIM: Since reproducibility of data is important in genetic association studies, a case control study was designed to find out whether LRPAP1 gene polymorphism is associated with gallstone disease in a Polish population. SUBJECTS: Two hundred eighty-nine Polish Caucasian gallstone disease patients and 251 healthy controls participated in the study. METHODS: A 37-bp insertion/deletion polymorphism in intron 5 of LRPAP1 (rs11267919) was determined by means of polymerase chain reaction assay. RESULTS: The frequencies and distribution of the insertion/deletion alleles did not differ significantly between gallstone disease patients and controls. No significant gender-related differences in allele frequencies or distributions were noted. CONCLUSION: The LRPAP1 insertion/deletion polymorphism is not associated with gallstone disease in a Polish population.