Human MSH2 binds to trinucleotide repeat DNA structures associated with neurodegenerative diseases

The expansion of trinucleotide repeat sequences is associated with several neurodegenerative diseases. The mechanism of this expansion is unknown but may involve slipped-strand structures where adjacent rather than perfect complementary sequences of a trinucleotide repeat become paired. Here, we have studied the interaction of the human mismatch repair protein MSH2 with slipped-strand structures formed from a triplet repeat sequence in order to address the possible role of MSH2 in trinucleotide expansion. Genomic clones of the myotonic dystrophy locus containing disease-relevant lengths of (CTG)n x (CAG)n triplet repeats were examined. We have constructed two types of slipped-strand structures by annealing complementary strands of DNA containing: (i) equal numbers of trinucleotide repeats (homoduplex slipped structures or S-DNA) or (ii) different numbers of repeats (heteroduplex slipped intermediates or SI-DNA). SI-DNAs having an excess of either CTG or CAG repeats were structurally distinct and could be separated electrophoretically and studied individually. Using a band-shift assay, the MSH2 was shown to bind to both S-DNA and SI-DNA in a structure- specific manner. The affinity of MSH2 increased with the length of the repeat sequence. Furthermore, MSH2 bound preferentially to looped-out CAG repeat sequences, implicating a strand asymmetry in MSH2 recognition. Our results are consistent with the idea that MSH2 may participate in trinucleotide repeat expansion via its role in repair and/or recombination.      

Molecular analysis of isolates from influenza B outbreaks in the U.S. and Nepal, 2005

Summary. Currently circulating influenza B viruses can be divided into two antigenically and genetically distinct lineages referred to by their respective prototype strains, B/Yamagata/16/88 and B/Victoria/2/87, based on amino acid differences in the hemagglutinin surface glycoprotein. During May and July 2005, clinical specimens from two early season influenza B outbreaks in Arizona and southeastern Nepal were subjected to antigenic (hemagglutinin inhibition) and nucleotide sequence analysis of hemagglutinin (HA1), neuraminidase (NA), and NB genes. All isolates exhibited little reactivity with the B/Shanghai/361/2002 (B/Yamagata-like) vaccine strain and significantly reduced reactivity with the previous 2003/04 B/Hong Kong/330/2001 (B/Victoria-like) vaccine strain. The majority of isolates were antigenically similar to B/Hawaii/33/2004, a B/Victoria-like reference strain. Sequence analysis indicated that 33 of 34 isolates contained B/Victoria-like HA and B/Yamagata-like NA and NB proteins. Thus, these outbreak isolates are both antigenically and genetically distinct from the current Northern Hemisphere vaccine virus strain as well as the previous 2003–04 B/Hong Kong/330/2001 (B/Victoria lineage) vaccine virus strain but are genetically similar to B/Malaysia/2506/2004, the vaccine strain proposed for the coming seasons in the Northern and Southern Hemispheres. Since these influenza B outbreaks occurred in two very distant geographical locations, these viruses may continue to circulate during the 2006 season, underscoring the importance of rapid molecular monitoring of HA, NA and NB for drift and reassortment.     

Yeast Rev1 protein promotes complex formation of DNA polymerase ζ with Pol32 subunit of DNA polymerase δ

Yeast DNA polymerase (Pol) δ, essential for DNA replication, is comprised of 3 subunits, Pol3, Pol31, and Pol32. Of these, the catalytic subunit Pol3 and the second subunit Pol31 are essential, whereas the Pol32 subunit is not essential for DNA replication. Although Pol32 is an integral component of Polδ, it is also required for translesion synthesis (TLS) by Polζ. To begin to decipher the bases of Pol32 involvement in Polζ-mediated TLS, here we examine whether Pol32 physically interacts with Polζ or its associated proteins and provide evidence for the physical interaction of Pol32 with Rev1. Rev1 plays an indispensable structural role in Polζ-mediated TLS and it binds the Rev3 catalytic subunit of Polζ. Here, we show that although Pol32 does not directly bind Polζ, Pol32 can bind the Rev1–Polζ complex through its interaction with Rev1. We find that Pol32 binding has no stimulatory effect on DNA synthesis either by Rev1 in the Rev1–Pol32 complex or by Polζ in the Polζ–Rev1–Pol32 complex, irrespective of whether proliferating cell nuclear antigen has been loaded onto DNA or not. We discuss evidence for the biological significance of Rev1 binding to Pol32 for Polζ function in TLS and suggest a structural role for Rev1 in modulating the binding of Polζ with Pol32 in Polδ stalled at a lesion site.     

Missile injuries in head — neck and maxillo-facial region — an experience in eastern nepal

Ballistic injuries to head-neck and maxillofacial region is quite common problem nowadays. Most of the time the injuries seem to be dreadful but the mechanism of the injuries caused by ballistics and the anatomical conditions of maxillofacial and head-neck region mitigate the severity of the injuries. Proper primary management followed by reconstruction and management of associated injuries decreases the mortality and morbidity of missile injuries in head-neck and maxillofacial region. Eleven cases of missile injuries in head-neck and maxillofacial region are included in the present study. The mechanism of the injury and the ideal management strategy for the ballistics injuries in the region has been discussed in the article.     

Pharmacophore-based predictive model generation for potent antimalarials targeting haem detoxification pathway

Pharmacophore hypotheses were developed for molecules having antimalarial activities targeting the haem detoxification pathway of the malaria parasite. A training set consisting of 23 compounds was selected to generate these hypotheses, and their activities were evaluated for haem polymerization inhibition and against chloroquine-sensitive (3D7) as well as chloroquine-resistant (K1) strains of p. falciparum. The models were cross-validated by Fischer’s randomization test at a 95% confidence level. The model developed against chloroquine-resistant malaria parasites was found to yield the best predictions among the three models.     

Maternal and child health services in rural Nepal: does access or quality matter more?

This study seeks to establish the relative importance of service access and quality on utilization of preventive health services in the western and middle-western Hill region of Nepal. Access was measured in terms of travel time to the nearest health post and coverage by outreach workers. The quality of static services was defined in structural terms: physical infrastructure, number of staff, availability of drugs and holding of special maternal and child health clinics. The initial analysis showed that no single indicator of quality was of overriding importance and therefore an overall quality index was constructed. After adjustment for access and for socioeconomic characteristics of families and communities, a very pronounced relationship between overall structural quality of the nearest health post and service uptake persisted. The adjusted odds of using some form of antenatal service were 6.6 times higher in the catchment areas of high quality posts than in areas served by low quality posts. The corresponding figure for receipt of BCG vaccination is 8.1. By comparison, the effects of travel time to the nearest health post are modest. Uptake of services is about twice as high when there is a health post in the community. Regular monthly visits by outreach workers also had a marked effect on service utilization. These results suggest that investment in the quality of health posts is more important than further increases in their number and that a further expansion of outreach services is a priority.     

Global health goals: lessons from the worldwide effort to eradicate poliomyelitis

The Global Polio Eradication Initiative was launched in 1988. Assessment of the politics, production, financing, and economics of this international effort has suggested six lessons that might be pertinent to the pursuit of other global health goals. First, such goals should be based on technically sound strategies with proven operational feasibility in a large geographical area. Second, before launching an initiative, an informed collective decision must be negotiated and agreed in an appropriate international forum to keep to a minimum long-term risks in financing and implementation. Third, if substantial community engagement is envisaged, efficient deployment of sufficient resources at that level necessitates a defined, time-limited input by the community within a properly managed partnership. Fourth, although the so-called fair-share concept is arguably the best way to finance such goals, its limitations must be recognised early and alternative strategies developed for settings where it does not work. Fifth, international health goals must be designed and pursued within existing health systems if they are to secure and sustain broad support. Finally, countries, regions, or populations most likely to delay the achievement of a global health goal should be identified at the outset to ensure provision of sufficient resources and attention. The greatest threats to poliomyelitis eradication are a financing gap of US 210 million dollars and difficulties in strategy implementation in at most five countries.     

Avoidance of cyclosporine in renal transplantation: effects of daclizumab, mycophenolate mofetil, and steroids

Cyclosporine (CsA) has been implicated in both acute and chronic graft dysfunction. The addition of humanized IL-2 receptor antibody daclizumab (DZB) to CsA-based immunosuppression decreases the rate of acute renal transplant rejection. Therefore, 45 patients were evaluated in an immunosuppressive protocol that included DZB, mycophenolate mofetil (MMF), and steroids without CsA. This was a prospective, nonrandomized, open-label trial of the efficacy and safety of the treatment. DZB was given intravenously at 2 mg/kg before transplantation and then at 1 mg/kg every 2 wk for four doses, MMF was given orally at 3 g/d, and methylprednisolone/prednisone was given at 7 mg/kg per day and tapered to 15 mg/d at 6 mo. CsA was added to the regimen when patients developed acute rejection episodes or adverse effects to steroids or MMF; 49% of patients were spared CsA maintenance. Patients without CsA had lower serum creatinine at 6 mo and needed fewer medications to control BP. Incidence of biopsyproven rejections was 31% and occurred early (median, 10 d). These rejection episodes occurred earlier in cadaver transplants (median, 7 d) and later in living donor transplants (median, 62 days). Acute rejections occurred at a higher frequency (46% versus 34%) and earlier (6.5 versus 15 d) in patients with delayed graft function compared with patients without delayed graft function. Most of the rejections were moderate and easily reversible. The actuarial 1-yr graft survival was 95% with 100% patient survival.