High-density antimicrobial peptide coating with broad activity and low cytotoxicity against human cells.

Medical device-associated infections are a multi-billion dollar burden for the worldwide healthcare systems. The modification of medical devices with non-leaching coatings capable of killing microorganisms on contact is one of the strategies being investigated to prevent microorganism colonization. Here we developed a robust antimicrobial coating based on the chemical immobilization of the antimicrobial peptide (AMP), cecropin-melittin (CM), on gold nanoparticles coated surfaces. The concentration of AMP immobilized (110 µg/cm(2)) was higher than most of the studies reported so far (<10 µg/cm(2)). This translated onto a coating with high antimicrobial activity against Gram positive and negative bacteria sp., as well as multi-drug resistant bacteria. Studies with E. coli reporter bacteria showed that these coatings induced the permeability of the outer membrane of bacteria in less than 5 min and the inner membrane in approximately 20 min. Importantly, the antimicrobial properties of the coating are maintained in the presence of 20% (v/v) human serum, and have low probability to induce bacteria resistance. We further show that coatings have low toxicity against human endothelial and fibroblast cells and is hemocompatible since it does not induce platelet and complement activation. The antimicrobial coating described here may be promising to prevent medical device-associated infections. STATEMENT OF SIGNIFICANCE: In recent years, antimicrobial peptides (AMPs) have been chemically immobilized on surfaces of medical devices to render them with antimicrobial properties. Surfaces having immobilized cationic peptides are susceptible to be adsorbed by plasma proteins with the subsequent loss of antimicrobial activity. Furthermore, with the exception of very few studies that have determined the cytotoxicity of surfaces in mammalian cells, the effect of the immobilized AMP on human cells is relatively unknown. Here we report a coating based on cecropin-melittin peptide (CM) that maintains its antimicrobial activity against Gram-positive and negative bacteria including multi-drugs resistance bacteria in the presence of serum and has relatively low cytotoxicity against human cells. The reported coatings may be translated on to variety of substrates (glass and titanium) and medical devices to prevent device-associated microbial infection.

A labor- and cost-effective non-optical semiconductor (Ion Torrent) next-generation sequencing of the SLC12A3 and CLCNKA/B genes in Gitelman's syndrome patients.

Gitelman's syndrome (GS) is a rare recessive disorder caused by mutations in the renal salt-handling genes SLC12A3 and CLCNKB. Our aim was to develop a next-generation sequencing (NGS) procedure for these genes based on two-tubes multiplex amplification of DNA pools and semiconductor sequencing with the Ion Torrent Personal Genome Machine (PGM). We created one pool with DNA from 20 GS patients previously Sanger sequenced for the coding exons of SLC12A3. A total of 13 mutations present in 11 of these patients were used as control variants to validate the NGS procedure. The full coding sequence of SLC12A3, CLCNKB and CLCNKA was amplified in only two Ampliseq tubes and processed and sequenced with the PGM. Large SLC12A3 and CLCNKB deletions were ascertained through multiplex ligation-dependent probe amplification in some patients. With the exception of the SLC12A3 exon 9, all the amplicons were successfully read and 12 of the 13 control variants were detected. The analysis of CLCNKB showed four putative mutations in the GS pool that were further assigned to specific patients. Two patients were heterozygous compounds for a single-nucleotide mutation and a large deletion at SLC12A3 or CLCNKB. We reported a NGS procedure that would facilitate the rapid and cost-effective large-scale screening of the three renal salt-handling genes. In addition to characterize the mutational spectrum of GS patients, the described procedure would facilitate the rapid and cost-effective screening of these genes at a population scale.

La acidosis tubular renal distal: una enfermedad hereditaria en la que no se pueden eliminar los hidrogeniones / Distal renal tubular acidosis: a hereditary disease with an inadequate urinary H+ excretion

La acidosis tubular renal distal (ATRD) o ATR tipo I se caracteriza por una disminución en la excreción urinaria de los hidrogeniones H+ y del amonio. En los niños afectados por ATRD hay retraso en el crecimiento, vómito, estreñimiento, falta de apetito, polidipsia y poliuria, nefrocalcinosis, debilidad y hasta parálisis muscular por la hipopotasemia. En este trabajo se resumen los avances en el estudio genético de la ATRD en las poblaciones hasta ahora estudiadas. La ATRD es heterogénea, por lo que también se analizan los transportadores y canales iónicos que se han identificado hasta ahora en las células intercaladas alfa del túbulo colector, y que podrían explicar los casos de ATRD que no se asocian con los genes hasta ahora estudiados. La ATRD puede ser autosómica dominante o autosómica recesiva. La ATRD autosómica recesiva se manifiesta en los primeros meses de vida, cursa con nefrocalcinosis y sordera temprana o tardía. La ATRD autosómica dominante es menos severa y aparece en la adolescencia o en la etapa adulta, y puede o no presentar nefrocalcinosis. En las células intercaladas alfa de los túbulos colectores se lleva a cabo la excreción urinaria de la carga ácida: los ácidos titulables (fosfatos) y el amonio. La ATRD autosómica recesiva se asocia con mutaciones en los genes ATP6V1B1, ATP6V0A4 y SLC4A1, los cuales codifican las subunidades a4 y B1 de la V-ATPasa y el intercambiador de bicarbonato/cloruro AE1, respectivamente. En contraste, la ATRD autosómica dominante se relaciona con mutaciones solo en AE1 (AU)

Distal renal tubular acidosis (dRTA) or RTA type I is characterised by reduced H+ hydrogen ions and ammonium urinary excretion. In children affected by dRTA there is stunted growth, vomiting, constipation, loss of appetite, polydipsia and polyuria, nephrocalcinosis, weakness and muscle paralysis due to hypokalaemia. This work summarises progress made in dRTA genetic studies in populations studied so far. DRTA is heterogeneous and as such, transporters and ion channels are analysed which have been identified in alpha-intercalated cells of the collecting duct, which could explain cases of dRTA not associated with the hitherto studied genes. DRTA can be autosomal dominant or autosomal recessive. Autosomal recessive dRTA appears in the first months of life and progresses with nephrocalcinosis and early or late hearing loss. Autosomal dominant dRTA is less severe and appears during adolescence or adulthood and may or may not develop nephrocalcinosis. In alpha-intercalated cells of the collecting duct, the acid load is deposited into the urine as titratable acids (phosphates) and ammonium. Autosomal recessive dRTA is associated with mutations in genes ATP6V1B1, ATP6V0A4 and SLC4A1, which encode subunits a4 and B1 of V-ATPase and the AE1 bicarbonate/chloride exchanger respectively. By contrast, autosomal dominant dRTA is only related to mutations in AE1 (AU)

Distal renal tubular acidosis: a hereditary disease with an inadequate urinary H⁺ excretion.

Distal renal tubular acidosis (dRTA) or RTA type I is characterised by reduced H+ hydrogen ions and ammonium urinary excretion. In children affected by dRTA there is stunted growth, vomiting, constipation, loss of appetite, polydipsia and polyuria, nephrocalcinosis, weakness and muscle paralysis due to hypokalaemia. This work summarises progress made in dRTA genetic studies in populations studied so far. DRTA is heterogeneous and as such, transporters and ion channels are analysed which have been identified in alpha-intercalated cells of the collecting duct, which could explain cases of dRTA not associated with the hitherto studied genes. DRTA can be autosomal dominant or autosomal recessive. Autosomal recessive dRTA appears in the first months of life and progresses with nephrocalcinosis and early or late hearing loss. Autosomal dominant dRTA is less severe and appears during adolescence or adulthood and may or may not develop nephrocalcinosis. In alpha-intercalated cells of the collecting duct, the acid load is deposited into the urine as titratable acids (phosphates) and ammonium. Autosomal recessive dRTA is associated with mutations in genes ATP6V1B1, ATP6V0A4 and SLC4A1, which encode subunits a4 and B1 of V-ATPase and the AE1 bicarbonate/chloride exchanger respectively. By contrast, autosomal dominant dRTA is only related to mutations in AE1.

Relationships between vertical jump strength metrics and 5 meters sprint time.

The aim of this study was to examine the relationship between short sprint time (5 m) and strength metrics of the countermovement jump (CMJ) using a linear transducer in a group of trained athletes. Twenty-five male, trained subjects volunteered to participate in the study. Each volunteer performed 3 maximal CMJ trials on a Smith machine. Peak instantaneous power was calculated by the product of velocity taken with the linear transducer. For sprint testing, each subject performed three maximum 5 m sprints. Only the best attempt was considered in both tests. Pearson product-moment correlation coefficients between 5 m sprint performance and strength metrics of the CMJ were generally positive and of clear moderate to strong magnitude (r = -0.664 to -0.801). More noticeable was the significant predictive value of bar displacement time (r= ∼0.70) to sprint performance. Nevertheless, a non-significant predictive value of peak bar velocity and rate of force development measurements was found. These results underline the important relationship between 5 m sprint and maximal lower body strength, as assessed by the force, power and bar velocity displacement. It is suggested that sprinting time performance would benefit from training regimens aimed to improve these performance qualities.

Genetic studies in a family with distal renal tubular acidosis and sensorineural deafness.

Distal renal tubular acidosis (RTA) with sensorineural deafness is a rare entity, inherited in an autosomal recessive manner. It is caused by mutations in the ATP6V1B1 gene, leading to defective function of H+-ATPase pump in the distal nephron, cochlea and endolymphatic sac. We report two siblings with distal RTA and sensorineural deafness having mutation in the first coding exon of the gene, resulting in a non functional protein. The parents were found to be carriers for the mutation.

Differential gene expression induced by growth hormone treatment in the uremic rat growth plate.

OBJECTIVES: Treatment with growth hormone (GH) improves growth retardation of chronic renal failure. cDNA microarrays were used to investigate GH-induced modifications in gene expression in the tibial growth plate of young rats. DESIGN: RNA was extracted from the tibial growth plate from two groups, untreated and treated with GH, of young rats made uremic by subtotal nephrectomy (n=10). To validate changes shown by the Agilent oligo microarrays, some modulated genes known to play a physiological role in growth plate metabolism were analyzed by real-time quantitative polymerase chain reaction (qPCR). RESULTS: The microarrays showed that GH modified the expression of 224 genes, 195 being upregulated and 29 downregulated. qPCR results confirmed the sense of expression change found in the arrays for insulin-like growth factor I, insulin-like growth factor II, collagen V alpha 1, bone morphogenetic protein 3 and proteoglycan type II. CONCLUSIONS: This study shows for the first time the profile of growth plate gene expression modifications caused by GH treatment in experimental uremia and provides a basis to further investigate selected individual genes with potential implication in the stimulating effect on the growth of GH treatment in chronic renal failure.

Rapamycin retards growth and causes marked alterations in the growth plate of young rats.

Rapamycin is a potent immunosuppressant with antitumoral properties widely used in the field of renal transplantation. To test the hypothesis that the antiproliferative and antiangiogenic activity of rapamycin interferes with the normal structure and function of growth plate and impairs longitudinal growth, 4-week-old male rats (n = 10/group) receiving 2 mg/kg per day of intraperitoneal rapamycin (RAPA) or vehicle (C) for 14 days were compared. Rapamycin markedly decreased bone longitudinal growth rate (94 +/- 3 vs. 182 +/- 3 microm/day), body weight gain (60.2 +/- 1.4 vs. 113.6 +/- 1.9 g), food intake (227.8 +/- 2.6 vs. 287.5 +/- 3.4 g), and food efficiency (0.26 +/- 0.00 vs. 0.40 +/- 0.01 g/g). Signs of altered cartilage formation such as reduced chondrocyte proliferation (bromodeoxiuridine-labeled cells 32.9 +/- 1.4 vs. 45.2 +/- 1.1%), disturbed maturation and hypertrophy (height of terminal chondrocytes 26 +/- 0 vs. 29 +/- 0 microm), and decreased cartilage resorption (18.7 +/- 0.5 vs. 31.0 +/- 0.8 tartrate-resistant phosphatase alkaline reactive cells per 100 terminal chondrocytes), together with morphological evidence of altered vascular invasion, were seen in the growth plate of RAPA animals. This study indicates that rapamycin can severely impair body growth in fast-growing rats and distort growth-plate structure and dynamics. These undesirable effects must be kept in mind when rapamycin is administered to children.

Distal RTA with nerve deafness: clinical spectrum and mutational analysis in five children.

Distal renal tubular acidosis (RTA) with nerve deafness is caused by mutations in the ATP6V1B1 gene causing defective function of the H+ -ATPase proton pump. We report five acidotic children (four males) from four unrelated families: blood pH 7.21-7.33, serum bicarbonate 10.8-14.7 mEq/l, minimum urinary pH 6.5-7.1 and fractional excretion of bicarbonate in the presence of normal bicarbonatemia 1.1-5.7%. Growth retardation and nephrocalcinosis, but not hypercalciuria, were common presenting manifestations. Hearing was normally preserved in one of the patients whose sister was severely deaf. One child was homozygous for a known mutation in exon 1: C>T (R31X). Three children were homozygous for a splicing mutation, intron 6 + 1G>A. The other patient was a compound heterozygote, having this mutation and a previously unreported mutation in exon 10: G>A (E330K). Our report shows that hearing loss is not always present in the syndrome of distal renal tubular acidosis with nerve deafness and the absence of hypercalciuria at diagnosis and describes a new mutation responsible for the disease in the ATP6V1B1 gene.