Alcohol's role in the deaths of BC children and youth

OBJECTIVE: To determine the prevalence and context of alcohol use in the deaths of children and youth reviewed by the BC Children's Commission. METHODS: In 489 case reviews of BC children and youth, we examined the role that alcohol may have had at the time of death or whether there was a history of alcohol use either by the deceased child or another person in the child's life. RESULTS: Alcohol is most prevalent in the lives of 15-18 year olds. It is present at the time of death in two fifths of Motor Vehicle Incidents (MVI) and one third of suicides and drownings. INTERPRETATION: Alcohol has a profound presence in the lives and deaths of children reviewed by the Children's Commission. Enhancing deterrence laws and alcohol control policies, and increasing public awareness are warranted.     

Genotype phenotype correlation in a pediatric population with antithrombin deficiency

Inherited antithrombin (AT) deficiency is a rare autosomal dominant disorder, caused by mutations in the AT gene (SERPINC1). Considering that the genotype phenotype relationship in AT deficiency patients remains unclear, especially in pediatric patients, the aim of our study was to evaluate genotype phenotype correlation in a Serbian pediatric population. A retrospective cohort study included 19 children younger than 18 years, from 15 Serbian families, with newly diagnosed AT deficiency. In 21% of the recruited families, mutations affecting exon 4, 5, and 6 of the SERPINC1 gene that causes type I AT deficiency were detected. In the remaining families, the mutation in exon 2 causing type II HBS (AT Budapest 3) was found. Thrombosis events were observed in 1 (33%) of those with type I, 11 (85%) of those with AT Budapest 3 in the homozygous respectively, and 1(33%) in the heterozygous form. Recurrent thrombosis was observed only in AT Budapest 3 in the homozygous form, in 27% during initial treatment of the first thrombotic event. Abdominal venous thrombosis and arterial ischemic stroke, observed in almost half of the children from the group with AT Budapest 3 in the homozygous form, were unprovoked in all cases.

Conclusion: Type II HBS (AT Budapest 3) in the homozygous form is a strong risk factor for arterial and venous thrombosis in pediatric patients.

Transmembrane proteins in the tight junction barrier.

Three types of transmembrane proteins have been identified within the tight junction, but it remains to be determined how they provide the molecular basis for regulating the paracellular permeability for water, solutes, and immune cells. Several of these proteins localize specifically within the continuous cell-to-cell contacts of the tight junction. One of these, occludin, is a cell adhesion molecule that has been demonstrated to influence ion and solute permeability. The claudins are a family of four-membrane spanning proteins; unexpectedly, other members of this family have already been characterized without recognizing their relationship to tight junctions. Junction adhesion molecule, the most recently identified tight junction component, is a member of the Ig superfamily and influences the paracellular transmigration of immune cells. A plaque of cytoplasmic proteins under the junction may be responsible for scaffolding the transmembrane proteins, creating a link to the perijunctional actin cytoskeleton and transducing regulatory signals that control the paracellular barrier.     

Gene‐environment interaction between the MMP9 C–1562T promoter variant and cigarette smoke in the pathogenesis of chronic obstructive pulmonary disease

The aetiology of chronic obstructive pulmonary disease (COPD) is complex. While cigarette smoking is a well‐established cause of COPD, a myriad of assessed genetic factors has given conflicting data. Since gene‐environment interactions are thought to be implicated in aetiopathogenesis of COPD, we aimed to examine the matrix metalloproteinase (MMP) 9 C–1562T (rs3918242) functional variant and cigarette smoke in the pathogenesis of this disease. The distribution of the MMP9 C–1562T variant was analyzed in COPD patients and controls with normal pulmonary function from Serbia. Interaction between the C–1562T genetic variant and cigarette smoking was assessed using a case‐control model. The response of the C–1562T promoter variant to cigarette smoke condensate (CSC) exposure was examined using a dual luciferase reporter assay. The frequency of T allele carriers was higher in the COPD group than in smoker controls (38.4% vs. 20%; OR = 2.7, P = 0.027). Interaction between the T allele and cigarette smoking was identified in COPD occurrence (OR = 4.38, P = 0.005) and severity (P = 0.001). A functional analysis of the C–1562T variant demonstrated a dose‐dependent and allele‐specific response (P < 0.01) to CSC. Significantly higher MMP9 promoter activity following CSC exposure was found for the promoter harboring the T allele compared to the promoter harboring the C allele (P < 0.05). Our study is the first to reveal an interaction between the MMP9–1562T allele and cigarette smoke in COPD, emphasising gene‐environment interactions as a possible cause of lung damage in the pathogenesis of COPD. Environ. Mol. Mutagen. 57:447–454, 2016. © 2016 Wiley Periodicals, Inc.     

Phosphate forms an unusual tripodal complex with the Fe-Mn center of sweet potato purple acid phosphatase

Purple acid phosphatases (PAPs) are a family of binuclear metalloenzymes that catalyze the hydrolysis of phosphoric acid esters and anhydrides. A PAP in sweet potato has a unique, strongly antiferromagnetically coupled Fe(III)-Mn(II) center and is distinguished from other PAPs by its increased catalytic efficiency for a range of activated and unactivated phosphate esters, its strict requirement for Mn(II), and the presence of a mu-oxo bridge at pH 4.90. This enzyme displays maximum catalytic efficiency (k(cat)/K(m)) at pH 4.5, whereas its catalytic rate constant (k(cat)) is maximal at near-neutral pH, and, in contrast to other PAPs, its catalytic parameters are not dependent on the pK(a) of the leaving group. The crystal structure of the phosphate-bound Fe(III)-Mn(II) PAP has been determined to 2.5-A resolution (final R(free) value of 0.256). Structural comparisons of the active site of sweet potato, red kidney bean, and mammalian PAPs show several amino acid substitutions in the sweet potato enzyme that can account for its increased catalytic efficiency. The phosphate molecule binds in an unusual tripodal mode to the two metal ions, with two of the phosphate oxygen atoms binding to Fe(III) and Mn(II), a third oxygen atom bridging the two metal ions, and the fourth oxygen pointing toward the substrate binding pocket. This binding mode is unique among the known structures in this family but is reminiscent of phosphate binding to urease and of sulfate binding to lambda protein phosphatase. The structure and kinetics support the hypothesis that the bridging oxygen atom initiates hydrolysis.     

Heterogeneity in expression and subcellular localization of claudins 2, 3, 4, and 5 in the rat liver, pancreas, and gut

BACKGROUND & AIMS: Paracellular transport varies widely among epithelia of the gastrointestinal tract. We determined whether members of the claudin family of tight junction proteins are differentially expressed consistent with a potential role in creating these variable properties. METHODS: Rabbit polyclonal antibodies were produced against peptides from claudins 2 through 5. The distribution of individual claudins was detected by immunoblotting, and their cell type and subcellular localization were determined by immunofluorescence on cryosections of rat liver, pancreas, stomach, and small and large intestine. RESULTS: All antibodies detected single bands of the expected size on immunoblots and were monospecific based on peptide competition studies. Immunoblotting detected strong differences among tissues in the expression level of each claudin. Immunolocalization confirmed these differences and revealed striking variations in expression patterns. In the liver, claudin 2 shows a lobular gradient increasing from periportal to pericentral hepatocytes, claudin 3 is uniformly expressed, claudin 4 is absent, and claudin 5 is only expressed in endothelial junctions. In the pancreas, claudin 2 is only detected in junctions of the duct epithelia, claudin 5 only in junctions of acinar cells, whereas claudin 3 and 4 are in both. Among differences in the gut are a crypt-to-villus decrease in claudin 2, a highly restricted expression of claudin 4 to colonic surface cells, and the finding that some claudins can be junctional, lateral, or show a gradient in junctional vs. lateral localization along the crypt-to-villus surface axis. CONCLUSIONS: Claudins have very different expression patterns among and within gastrointestinal tissues. We propose these patterns underlie differences in paracellular permeability properties, such as electrical resistance and ion selectivity that would complement known differences in transcellular transport.