Exclusion of the Locus for Autosomal Recessive Pseudohypoaldosteronism Type 1 from the Mineralocorticoid Receptor Gene Region on Human Chromosome 4q by Linkage Analysis.

Pseudohypoaldosteronism type 1 (PHA1) is an uncommon inherited disorder characterized by salt-wasting in infancy arising from target organ unresponsiveness to mineralocorticoids. Clinical expression of the disease varies from severely affected infants who may die to apparently asymptomatic individuals. Inheritance is Mendelian and may be either autosomal dominant or autosomal recessive. A defect in the mineralocorticoid receptor has been implicated as a likely cause of PHA1. The gene for human mineralocorticoid receptor (MLR) has been cloned and physically mapped to human chromosome 4q31.1-31.2. The etiological role of MLR in autosomal recessive PHA1 was investigated by performing linkage analysis between PHA1 and three simple sequence length polymorphisms (D4S192, D4S1548, and D4S413) on chromosome 4q in 10 consanguineous families. Linkage analysis was carried out assuming autosomal recessive inheritance with full penetrance and zero phenocopy rate using the MLINK program for two-point analysis and the HOMOZ program for multipoint analysis. Lod scores of less than -2 were obtained over the whole region from D4S192 to D4S413 encompassing MLR. This provdes evidence against MLR as the site of mutations causing PHA1 in the majority of autosomal recessive families

Could a defective epithelial sodium channel lead to bronchiectasis

<p>Abstract</p> <p>Background</p> <p>Bronchiectasis is defined as a permanent dilation of the airways arising from chronic bronchial inflammation/infection. In 50% of cases, no etiology can be identified. Recently, the role of the epithelial sodium channel ENaC has been pointed out in the pathophysiology of cystic fibrosis, a disease due to mutations in the <it>CFTR </it>gene and causing bronchiectasis in the airways. Moreover, it was found that transgenic mice overexpressing <it>ENaCβ </it>present cystic fibrosis-like lung disease symptoms. Our aim was to evaluate if a defective ENaC protein could be involved in the development of bronchiectasis.</p> <p>Methods</p> <p>We extensively analysed <it>ENaCβ </it>and <it>γ </it>genes in 55 patients with idiopathic bronchiectasis and without two mutations in the coding regions of <it>CFTR</it>. Thirty-eight patients presented functional abnormalities suggesting impaired sodium transport (abnormal sweat chloride concentration or nasal potential difference measurement), and 17 had no such evidence.</p> <p>Results</p> <p>Sequencing of the exons and flanking introns of the <it>ENaCβ </it>and <it>γ </it>gene identified five different amino-acid changes (p.Ser82Cys, p.Pro369Thr, p.Asn288Ser in <it>ENaCβ </it>; and p.Gly183Ser, p.Glu197Lys in <it>ENaCγ</it>) in heterozygous state in 8 patients. The p.Ser82Cys amino-acid change was found in 3 unrelated patients who were also heterozygous for a <it>CFTR </it>mutation or variant (1 p.F508del, 1 IVS8-5T, and 1 IVS8-5T:1716G>A (p.E528E)). The other mutations were found in patients without <it>CFTR </it>mutation, the p.Glu197Lys mutation in 2 patients and the other variants in single patients. Among the 8 patients bearing an <it>ENaC </it>mutation, 5 had functional abnormalities suggesting impaired sodium transport.</p> <p>Conclusion</p> <p>Our results suggest that several variants in <it>ENaCβ </it>and <it>γ </it>genes might be deleterious for ENaC function and lead to bronchiectasis, especially in patients who are trans-heterozygotes for <it>ENaCβ/CFTR </it>mutations or variants.</p

Oxidative stress and adrenocortical insufficiency

This work has been supported by the Wellcome Trust (Clinical Research Training Fellowship grant number WT095984AIA to R P) and the Medical Research Council UK (project grant number MR/K020455/1 to L A M

An epidemiological study on anemia among institutionalized people with intellectual and/or motor disability with special reference to its frequency, severity and predictors

BACKGROUND: To examine the type, frequency, severity, and predictors of anemia and its relationship with co-morbid conditions among institutionalized people with intellectual and/or motor disability. METHODS: We conducted a cross-sectional study at a public facility for people with intellectual and/or motor disability in Ibaraki prefecture, Japan. Health checkup data obtained in 2001 from 477 people with intellectual disability (male: 286, average age 40.6 ± 12.3; female: 191, average age 45.1 ± 11.6) were retrospectively reviewed. RESULTS: The prevalence of anemia among male participants was higher than in female participants for each disability category (intellectual disability, 41.1%, 4.2%; cerebral palsy, 37.5%, 4.8%; Down's syndrome, 15.0%, 0%; severe motor and intellectual disabilities, 61.9%, 16.7%). Most participants with anemia (93.8 – 100%) showed a normocytic normochromic anemia pattern. Multivariate analysis revealed that factors related to an increase in frequency included sex (male), low body mass index (BMI), use of anticonvulsants or major tranquilizers, and a high zinc sulfate turbidity test (ZTT) value. No clinically diagnosed co-morbid condition was found to be related to the presence of anemia. CONCLUSION: A high frequency of mild normocytic normochromic anemia in institutionalized people with intellectual and/or motor disability was observed, particularly among males. Medications and chronic inflammation may increase the risk of anemia

Autosomal dominant pseudohypoaldosteronism type 1 with a novel splice site mutation in MR gene

<p>Abstract</p> <p>Background</p> <p>Autosomal dominant pseudohypoaldosteronism type 1 (PHA1) is a rare inherited condition that is characterized by renal resistance to aldosterone as well as salt wasting, hyperkalemia, and metabolic acidosis. Renal PHA1 is caused by mutations of the human mineralcorticoid receptor gene (<it>MR</it>), but it is a matter of debate whether <it>MR </it>mutations cause mineralcorticoid resistance via haploinsufficiency or dominant negative mechanism. It was previously reported that in a case with nonsense mutation the mutant mRNA was absent in lymphocytes because of nonsense mediated mRNA decay (NMD) and therefore postulated that haploinsufficiency alone can give rise to the PHA1 phenotype in patients with truncated mutations.</p> <p>Methods and Results</p> <p>We conducted genomic DNA analysis and mRNA analysis for familial PHA1 patients extracted from lymphocytes and urinary sediments and could detect one novel splice site mutation which leads to exon skipping and frame shift result in premature termination at the transcript level. The mRNA analysis showed evidence of wild type and exon-skipped RT-PCR products.</p> <p>Conclusion</p> <p>mRNA analysis have been rarely conducted for PHA1 because kidney tissues are unavailable for this disease. However, we conducted RT-PCR analysis using mRNA extracted from urinary sediments. We could demonstrate that NMD does not fully function in kidney cells and that haploinsufficiency due to NMD with premature termination is not sufficient to give rise to the PHA1 phenotype at least in this mutation of our patient. Additional studies including mRNA analysis will be needed to identify the exact mechanism of the phenotype of PHA.</p

Pulmonary epithelial sodium-channel dysfunction and excess airway liquid in pseudohypoaldosteronism

Background: Active sodium absorption is the dominant mechanism of ion transport in airway epithelium, but its role in pulmonary physiology and airway host defense is unknown. To address this question, we studied the function of airway epithelial cells and determined the frequency of pulmonary symptoms in patients with systemic pseudohypoaldosteronism, a salt-losing disorder caused by loss-of-function mutations in the genes for the epithelial sodium channel. Methods: In nine patients 1.5 to 22 years of age who had systemic pseudohypoaldosteronism, we tested for mutations in the genes for the epithelial sodium channel, estimated the rate of sodium transport in the airway, determined the volume and ion composition of airway surface liquid, reviewed clinical features, collected laboratory data pertinent to pulmonary function, and, in three adults, measured mucociliary clearance. Results: The patients with systemic pseudohypoaldosteronism had loss-of-function mutations in the genes for the epithelial sodium-channel subunits, no sodium absorption from airway surfaces, and a volume of airway surface liquid that was more than twice the normal value. The mean (±SE) mucociliary transport rate was higher in the 3 adult patients than in 12 normal subjects (2.0 ± 0.7 vs. 0.5 ± 0.3 percent per minute, P = 0.009). Young patients (those five years of age or less) all had recurrent episodes of chest congestion, coughing, and wheezing, but no airway infections with Staphylococcus aureus or Pseudomonas aeruginosa. Older patients (those more than five years of age) had less frequent respiratory symptoms. Conclusions: Patients with systemic pseudohypoaldosteronism fail to absorb liquid from airway surfaces; the result is an increased volume of liquid in the airways. These results demonstrate that sodium transport has a role in regulating the volume of liquid on airway surfaces

Two Structures of a Thiazolinyl Imine Reductase from Yersinia enterocolitica Provide Insight into Catalysis and Binding to the Nonribosomal Peptide Synthetase Module of HMWP1

The thiazolinyl imine reductase from Yersinia enterocolitica (Irp3) catalyzes the NADPH-dependent reduction of a thiazoline ring in an intermediate for the formation of the siderophore yersiniabactin. Two structures of Irp3 were determined in the apo- (1.85 Å) and NADP+-bound (2.31 Å) forms. Irp3 shows structural homology to sugar oxidoreductases such as glucose-fructose oxidoreductase and 1,5-anhydro-D-fructose reductase, as well as to biliverdin reductase. A homology model of the thiazolinyl imine reductase from Pseudomonas aeruginosa (PchG) was generated. Extensive loop insertions are observed in the C-terminal domain that are unique to Irp3 and PchG and not found in the structural homologs that recognize small molecular substrates. These loops are hypothesized to be important for binding of the nonribosomal peptide synthetase modules (found in HMWP1 and PchF, respectively) to which the substrate of the reductase is covalently attached. A catalytic mechanism of proton donation from a general acid (either histidine-101 or tyrosine-128) and hydride donation from C4 of nicotinamide of the NADPH cofactor is proposed for reduction of the carbon-nitrogen double bond of the thiazoline

The monoclonal antibody EPR1614Y against the stem cell biomarker keratin K15 lacks specificity and reacts with other keratins

Keratin 15 (K15), a type I keratin, which pairs with K5 in epidermis, has been used extensively as a biomarker for stem cells. Two commercial antibodies, LHK15, a mouse monoclonal and EPR1614Y, a rabbit monoclonal, have been widely employed to study K15 expression. Here we report differential reactivity of these antibodies on epithelial cells and tissue sections. Although the two antibodies specifically recognised K15 on western blot, they reacted differently on skin sections and cell lines. LHK15 reacted in patches, whereas EPR1614Y reacted homogenously with the basal keratinocytes in skin sections. In cultured cells, LHK15 did not react with K15 deficient NEB-1, KEB-11, MCF-7 and SW13 cells expressing only exogenous K8 and K18 but reacted when these cells were transduced with K15. On the other hand, EPR1614Y reacted with these cells even though they were devoid of K15. Taken together these results suggest that EPR1614Y recognises a conformational epitope on keratin filaments which can be reconstituted by other keratins as well as by K15. In conclusion, this report highlights that all commercially available antibodies may not be equally specific in identifying the K15 positive stem cell