A paucity of liver disease in Canadian Inuit with chronic hepatitis B virus, subgenotype B6 infection.

Clinical observations suggest that chronic hepatitis B virus (HBV) infections in the Canadian Inuit are less often associated with serious adverse outcomes than has been described in other HBV-infected patient populations. The aim of this study was to document the clinical and biochemical features, liver-related morbidity and all-cause mortality in Canadian Inuit with chronic HBV infections. Administrative databases were reviewed for individuals identified as hepatitis B surface antigen (HBsAg) positive during a 1983-85 seroepidemiological survey of viral hepatitis in Baffin Island, Canada. An equal number of age- and gender-matched HBsAg-negative individuals from the same communities served as controls. Baseline HBV viral loads, genotypes and specific mutations were compared in HBsAg-positive survivors and nonsurvivors. A subset of surviving HBsAg-positive carriers were reassessed 25-30 years following their initial diagnosis for evidence of advanced liver disease and changes to their serological/virological findings. One hundred and forty four HBsAg-positive individuals were identified. All were Canadian Inuit. The mean age at diagnosis was 38 ± 17 years and 69 (61%) were male. Median follow-up was 23 years (range: 2-28 years). Viral quantitation from stored sera could be performed in 70 infected individuals. The median viral load was 4.3 log 10 IU/ml (range: 2.3-8.8 log 10 IU/ml), and all were genotype B, subgenotype B6. Liver biochemistry, morbidity and all-cause mortality rates were similar in HBsAg-positive carriers and controls. Following multivariate analyses, only age at diagnosis predicted mortality in HBsAg carriers. In a subset of 30 HBsAg-positive survivors who underwent follow-up assessments, clinical, biochemical and radiological examinations of the liver were essentially normal. 23/30 (77%) remained HBsAg positive and 17/19 (90%) HBV-DNA positive. The genotype and prevalence of genomic mutations in this cohort remained largely unchanged, but quantifiable viral loads were significantly lower (P < 0.003). The results of this study suggest that chronic HBV infections in the Canadian Inuit are infrequently associated with serious adverse outcomes. Whether this finding reflects unique features of the host, presence or absence of external factors that influence the course of HBV and/or intrinsic properties of the HBV B6 subgenotype remains to be determined.

Dietary sodium intake among Canadian adults with and without hypertension.

INTRODUCTION: Almost 30% of hypertension among Canadians may be attributed to excess dietary sodium. METHODS: We examined the average sodium intake of Canadians aged 30 years and over, with and without hypertension, by age, sex and diabetes status using 24-hour recall data from the 2004 Canadian Community Health Survey, Cycle 2.2, Nutrition. We compared absolute (crude) average sodium intake levels of those with and without hypertension to the 2009 Canadian Hypertension Education Program (CHEP) guidelines and adjusted average sodium intake between those with and without hypertension. RESULTS: Both those with and without diagnosed hypertension display average sodium intakes well above the 1500 mg/day recommended by the 2009 CHEP guidelines (2950 mg/day and 3175 mg/day, respectively). After confounding adjustment, those with hypertension have significantly higher average sodium intake (p = .0124). Stratified subgroup analyses found the average sodium intake among those with hypertension was higher for men between 30 and 49 years old (p = .0265), women between 50 and 69 years old (p = .0083) and those without diabetes (p = .0071) when compared to their counterparts without hypertension. CONCLUSION: Better approaches are needed to reduce sodium intake in hypertension patients, as well as the general population.

Viral hepatitis in a Canadian First Nations community.

Serological markers for hepatitis A (HAV), B (HBV) and C (HCV) were documented in 315 inhabitants (27%) of a central Manitoba First Nations community. Serologic evidence of HAV infection (anti-HAV positive) was almost universal (92%) by the age of 20 years. HBV infection (antibody to hepatitis B core antigen positive) had occurred in only 2.3% of the study population and no chronic carriers were identified. Serological evidence of HCV infection (anti-HCV positive) was documented in 2.2% of the population but ongoing viremia (HCV-RNA positive by polymerase chain reaction) was absent. The results of this study highlight the importance of universal HAV vaccination; likely reflect the efficacy of existing prenatal screening and immunoprophylaxis programs for HBV; and raise the possibility that First Nations peoples have an enhanced ability to spontaneously clear HCV.

Conserved Wat1/Pop3 WD-repeat protein of fission yeast secures genome stability through microtubule integrity and may be involved in mRNA maturation.

Accurate chromosome segregation is dependent upon the integrity of mitotic spindles, which pull each pair of sister chromatids towards opposite poles. In this study, we have characterised fission yeast pop3-5235, a diploidising mutant that is impaired in genome stability. Pop3 is the same as Wat1, a conserved protein containing 7 WD repeats. Pop3/Wat1 has also been isolated from a two-hybrid screen as a binding partner to Prp2, the large subunit of the essential splicing factor U2AF. In wat1 mutants, the cellular amount of alpha-tubulin is decreased to very low levels, which results in compromised microtubules and spindles, consequently leading to unequal chromosome separation. Further analysis shows that, in spite of the binding between Wat1 and Prp2, Wat1 may not be involved directly in splicing reactions per se. Instead, we find that Wat1 is required for the maintenance of alpha-tubulin mRNA levels; moreover, transcript levels of genes other than the alpha-tubulin gene are also equally decreased in this mutant. Wild-type Wat1, but not the mutant protein, forms a large complex in the cell with several other proteins, suggesting that Wat1 functions as a structural linker in the complex. The results suggest that Wat1 plays a role in mRNA maturation as a coupling protein between splicing and synthesis and/or stabilisation.

Fission yeast ch-TOG/XMAP215 homologue Alp14 connects mitotic spindles with the kinetochore and is a component of the Mad2-dependent spindle checkpoint.

The TOG/XMAP215-related proteins play a role in microtubule dynamics at its plus end. Fission yeast Alp14, a newly identified TOG/XMAP215 family protein, is essential for proper chromosome segregation in concert with a second homologue Dis1. We show that the alp14 mutant fails to progress towards normal bipolar spindle formation. Intriguingly, Alp14 itself is a component of the Mad2-dependent spindle checkpoint cascade, as upon addition of microtubule-destabilizing drugs the alp14 mutant is incapable of maintaining high H1 kinase activity, which results in securin destruction and premature chromosome separation. Live imaging of Alp14-green fluorescent protein shows that during mitosis, Alp14 is associated with the peripheral region of the kinetochores as well as with the spindle poles. This is supported by ChIP (chromatin immunoprecipitation) and overlapping localization with the kinetochore marker Mis6. An intact spindle is required for Alp14 localization to the kinetochore periphery, but not to the poles. These results indicate that the TOG/XMAP215 family may play a central role as a bridge between the kinetochores and the plus end of pole to chromosome microtubules.

The fission yeast gamma-tubulin complex is required in G(1) phase and is a component of the spindle assembly checkpoint.

Microtubule polymerization is initiated from the microtubule organizing centre (MTOC), which contains the gamma-tubulin complex. We have identified fission yeast Alp4 and Alp6, which are homologues of the gamma-tubulin-interacting proteins Sc.Spc97/Hs.Gcp2 and Sc. Spc98/Hs.Gcp3, respectively. The size of the fission yeast gamma-tubulin complex is large (>2000 kDa), comparable to that in metazoans. Both Alp4 and Alp6 localize to the spindle pole body (SPB) and also to the equatorial MTOC. Temperature-sensitive (ts) alp4 and alp6 mutants show two types of microtubular defects. First, monopolar mitotic spindles form. Secondly, abnormally long cytoplasmic microtubules appear that do not stop at the cell tips and are still associated with the SPB. Alp4 function is required in G(1) phase and ts mutants become lethal before S-phase. alp4 and alp6 mutants are hypersensitive to the microtubule- destabilizing drug thiabendazole (TBZ) and show a lethal 'cut' phenotype in its presence. Furthermore, alp4mad2 double mutants show an exaggerated multiple septation phenotype in TBZ. These results indicate that Alp4 and Alp6 may play a crucial role in the spindle pole-mediated checkpoint pathway.

A conserved small GTP-binding protein Alp41 is essential for the cofactor-dependent biogenesis of microtubules in fission yeast.

The proper folding of tubulins and their incorporation into microtubules consist of a series of reactions, in which evolutionarily conserved proteins, cofactors A to E, play a vital role. We have cloned a fission yeast gene (alp41(+)) which encodes a highly conserved small GTP-binding protein homologous to budding yeast CIN4 and human ARF-like Arl2. alp41(+) is essential, disruption of which results in microtubule dysfunction and growth polarity defects. Genetic analysis indicates that Alp41 plays a crucial role in the cofactor-dependent pathway, in which it functions upstream of the cofactor D homologue Alp1(D) and possibly in concert with Alp21(E).

Functional dissection and hierarchy of tubulin-folding cofactor homologues in fission yeast.

We describe the isolation of fission yeast homologues of tubulin-folding cofactors B (Alp11) and E (Alp21), which are essential for cell viability and the maintenance of microtubules. Alp11(B) contains the glycine-rich motif (the CLIP-170 domain) involved in microtubular functions, whereas, unlike mammalian cofactor E, Alp21(E) does not. Both mammalian and yeast cofactor E, however, do contain leucine-rich repeats. Immunoprecipitation analysis shows that Alp11(B) interacts with both alpha-tubulin and Alp21(E), but not with the cofactor D homologue Alp1, whereas Alp21(E) also interacts with Alp1(D). The cellular amount of alpha-tubulin is decreased in both alp1 and alp11 mutants. Overproduction of Alp11(B) results in cell lethality and the disappearance of microtubules, which is rescued by co-overproduction of alpha-tubulin. Both full-length Alp11(B) and the C-terminal third containing the CLIP-170 domain localize in the cytoplasm, and this domain is required for efficient binding to alpha-tubulin. Deletion of alp11 is suppressed by multicopy plasmids containing either alp21(+) or alp1(+), whereas alp21 deletion is rescued by overexpression of alp1(+) but not alp11(+). Finally, the alp1 mutant is not complemented by either alp11(+) or alp21(+). The results suggest that cofactors operate in a linear pathway (Alp11(B)-Alp21(E)-Alp1(D)), each with distinct roles.

Identification of novel temperature-sensitive lethal alleles in essential beta-tubulin and nonessential alpha 2-tubulin genes as fission yeast polarity mutants.

We have screened for temperature-sensitive (ts) fission yeast mutants with altered polarity (alp1-15). Genetic analysis indicates that alp2 is allelic to atb2 (one of two alpha-tubulin genes) and alp12 to nda3 (the single beta-tubulin gene). atb2(+) is nonessential, and the ts atb2 mutations we have isolated are dominant as expected. We sequenced two alleles of ts atb2 and one allele of ts nda3. In the ts atb2 mutants, the mutated residues (G246D and C356Y) are found at the longitudinal interface between alpha/beta-heterodimers, whereas in ts nda3 the mutated residue (Y422H) is situated in the domain located on the outer surface of the microtubule. The ts nda3 mutant is highly sensitive to altered gene dosage of atb2(+); overexpression of atb2(+) lowers the restrictive temperature, and, conversely, deletion rescues ts. Phenotypic analysis shows that contrary to undergoing mitotic arrest with high viability via the spindle assembly checkpoint as expected, ts nda3 mutants execute cytokinesis and septation and lose viability. Therefore, it appears that the ts nda3 mutant becomes temperature lethal because of irreversible progression through the cell cycle in the absence of activating the spindle assembly checkpoint pathway.

Effects on mood of a life-styles program for the rehabilitation of injured workers.

This study reports an examination into the effects on daily mood of participation in a life-styles program by injured workers. In the current prospective study, 14 participants completed the Memorial University Mood Scale (MUMS) prior to starting the program, at 1 month, 2 months, and at 3 months. They also completed the Memorial University Scale of Happiness (MUNSH) prior to entry and after three months. There were significant improvements on the MUMS subscales of positive mood and vigor as well as overall mood. There were no changes in negative mood. Neither the positive nor the negative dispositional subscales of the MUNSH revealed any change. The results were interpreted as indicating strong psychologic benefits of the life-styles program for injured workers and are also consistent with a recently proposed two-factor state/trait model of well-being.