Characterization of the third chitinase Chi18C of <Emphasis Type="Italic">Clostridium paraputrificum</Emphasis> M-21

A novel chitinase gene chiC of Clostridium paraputrificum M-21, a chitinolytic and hydrogen-gas-producing bacterium, was characterized along with its translated product. The chi18C gene encodes 683 amino acids (signal peptide included) with a deduced molecular weight of 74,651. Chi18C is a modular enzyme composed of a family-18 catalytic module of glycoside hydrolases, two reiterated modules of unknown function, and a family-12 carbohydrate-binding module. Recombinant Chi18C was active toward soluble and insoluble chitin preparations, and synthetic substrates such as 4-methylumbelliferyl-β-d-N-N′-N″-triacetylchitotriose, but not active toward 4-MU-N-acetylglucosamine or 4-MU-β-d-N-N′-diacetylchitobioside. Sodium dodecyl sulfate polyacrylamide gel electrophoresis and immunological analyses suggested that the expression of chi18C was inducible with chitinous substrates and that Chi18C was secreted into the culture medium. A possible role of Chi18C in the chitinolytic system of C. paraputrificum M-21 is discussed.     

Host genetics and viral load in primary HIV-1 infection: clear evidence for gene by sex interactions

Research in the past two decades has generated unequivocal evidence that host genetic variations substantially account for the heterogeneous outcomes following human immunodeficiency virus type 1 (HIV-1) infection. In particular, genes encoding human leukocyte antigens (HLA) have various alleles, haplotypes, or specific motifs that can dictate the set-point (a relatively steady state) of plasma viral load (VL), although rapid viral evolution driven by innate and acquired immune responses can obscure the long-term relationships between HLA genotypes and HIV-1-related outcomes. In our analyses of VL data from 521 recent HIV-1 seroconverters enrolled from eastern and southern Africa, HLA-A*03:01 was strongly and persistently associated with low VL in women (frequency = 11.3 %, P < 0.0001) but not in men (frequency = 7.7 %, P = 0.66). This novel sex by HLA interaction (P = 0.003, q = 0.090) did not extend to other frequent HLA class I alleles (n = 34), although HLA-C*18:01 also showed a weak association with low VL in women only (frequency = 9.3 %, P = 0.042, q > 0.50). In a reduced multivariable model, age, sex, geography (clinical sites), previously identified HLA factors (HLA-B*18, B*45, B*53, and B*57), and the interaction term for female sex and HLA-A*03:01 collectively explained 17.0 % of the overall variance in geometric mean VL over a 3-year follow-up period (P < 0.0001). Multiple sensitivity analyses of longitudinal and cross-sectional VL data yielded consistent results. These findings can serve as a proof of principle that the gap of “missing heritability” in quantitative genetics can be partially bridged by a systematic evaluation of sex-specific associations.     

Mechanism of Borrelia immune evasion by FhbA-related proteins

Immune evasion facilitates survival of Borrelia, leading to infections like relapsing fever and Lyme disease. Important mechanism for complement evasion is acquisition of the main host complement inhibitor, factor H (FH). By determining the 2.2 Å crystal structure of Factor H binding protein A (FhbA) from Borrelia hermsii in complex with FH domains 19–20, combined with extensive mutagenesis, we identified the structural mechanism by which B. hermsii utilizes FhbA in immune evasion. Moreover, structure-guided sequence database analysis identified a new family of FhbA-related immune evasion molecules from Lyme disease and relapsing fever Borrelia. Conserved FH-binding mechanism within the FhbA-family was verified by analysis of a novel FH-binding protein from B. duttonii. By sequence analysis, we were able to group FH-binding proteins of Borrelia into four distinct phyletic types and identified novel putative FH-binding proteins. The conserved FH-binding mechanism of the FhbA-related proteins could aid in developing new approaches to inhibit virulence and complement resistance in Borrelia.     

Complement factor H allotype 402H is associated with increased C3b opsonization and phagocytosis of Streptococcus pyogenes

The mechanisms driving bacterial chromosome segregation remain poorly characterized. While a number of factors influencing chromosome segregation have been described in recent years, none of them appeared to play an essential role in the process comparable to the eukaryotic centromere/spindle complex. The research community involved in bacterial chromosome was becoming familiar with the fact that bacteria have selected multiple redundant systems to ensure correct chromosome segregation. Over the past few years a new perspective came out that entropic forces generated by the confinement of the chromosome in the crowded nucleoid shell could be sufficient to segregate the chromosome. The segregating factors would only be required to create adequate conditions for entropy to do its job. In the article by Yazdi et al. ( 2012 ) in this issue of Molecular Microbiology, this model was challenged experimentally in live Escherichia coli cells. A Fis–GFP fusion was used to follow nucleoid choreography and analyse it from a polymer physics perspective. Their results suggest strongly that E. coli nucleoids behave as self‐adherent polymers. Such a structuring and the specific segregation patterns observed do not support an entropic like segregation model. Are we back to the pre‐entropic era?     

Improvement of long-term prognosis in patients with ovarian cancers by adjuvant sizofiran immunotherapy: a prospective randomized controlled study

The effect of immunotherapy using sizofiran (SPG) on the prognosis of patients with ovarian cancers was prospectively studied in a total of 68 patients, who were randomly assigned to either a cisplatin, adriamycin and cyclophosphamide (PAC) therapy group or a PAC plus SPG combination therapy group.The survival rate was significantly higher in patients with stage Ic, II or III cancers treated with the PAC plus SPG combination, compared with the patients treated with PAC alone. In the SPG-receiving patients with stage Ic or more advanced cancers who were treated with four cycles or more of PAC, the outcome was improved (Cox-Mantel, p=0.074; generalized Kruskal-Wallis, p=0.032). Similar improvement was also observed in the patients with non-serous adenocarcinomas (Cox-Mantel, p-0.076; generalized Krukal-Wallis, p=0.045). No side effects attributable to SPG were recorded.The present results suggest that the use of SPG in combination with long-term chemotherapy improves the postoperative prognosis in ovarian cancer patients.Abbreviations SPG sizofiran     

Genotype-Phenotype Correlations in CYP1B1-Associated Primary Congenital Glaucoma Patients Representing Two Large Cohorts from India and Brazil

BackgroundPrimary congenital glaucoma (PCG), occurs due to the developmental defects in the trabecular meshwork and anterior chamber angle in children. PCG exhibits genetic heterogeneity and the CYP1B1 gene has been widely implicated worldwide. Despite the diverse mutation spectra, the clinical implications of these mutations are yet unclear. The present study attempted to delineate the clinical profile of PCG in the background of CYP1B1 mutations from a large cohort of 901 subjects from India (n=601) and Brazil (n=300).MethodsGenotype-phenotype correlations was undertaken on clinically well characterized PCG cases from India (n=301) and Brazil (n=150) to assess the contributions of CYP1B1 mutation on a set of demographic and clinical parameters. The demographic (gender, and history of consanguinity) and quantitative clinical (presenting intraocular pressure [IOP] and corneal diameter [CD]) parameters were considered as binary and continuous variables, respectively, for PCG patients in the background of the overall mutation spectra and also with respect to the prevalent mutations in India (R368H) and Brazil (4340delG). All these variables were fitted in a multivariate logistic regression model using the Akaike Information Criterion (AIC) to estimate the adjusted odds ratio (OR) using the R software (version 2.14.1).ResultsThe overall mutation spectrum were similar across the Indian and Brazilian PCG cases, despite significantly higher number of homozygous mutations in the former (p=0.024) and compound heterozygous mutations in the later (p=0.012). A wide allelic heterogeneity was observed and only 6 mutations were infrequently shared between these two populations. The adjusted ORs for the binary (demographic) and continuous (clinical) variables did not indicate any susceptibility to the observed mutations (p>0.05).ConclusionsThe present study demonstrated a lack of genotype-phenotype correlation of the demographic and clinical traits to CYP1B1 mutations in PCG at presentation. However, the susceptibility of these mutations to the long-term progression of these traits are yet to be deciphered.     

Differences in HIV natural history among African and non-African seroconverters in Europe and seroconverters in sub-Saharan Africa

Introduction

It is unknown whether HIV treatment guidelines, based on resource-rich country cohorts, are applicable to African populations.

Methods

We estimated CD4 cell loss in ART-naïve, AIDS-free individuals using mixed models allowing for random intercept and slope, and time from seroconversion to clinical AIDS, death and antiretroviral therapy (ART) initiation by survival methods. Using CASCADE data from 20 European and 3 sub-Saharan African (SSA) cohorts of heterosexually-infected individuals, aged ≥15 years, infected ≥2000, we compared estimates between non-African Europeans, Africans in Europe, and Africans in SSA.

Results

Of 1,959 (913 non-Africans, 302 Europeans - African origin, 744 SSA), two-thirds were female; median age at seroconversion was 31 years. Individuals in SSA progressed faster to clinical AIDS but not to death or non-TB AIDS. They also initiated ART later than Europeans and at lower CD4 cell counts. In adjusted models, Africans (especially from Europe) had lower CD4 counts at seroconversion and slower CD4 decline than non-African Europeans. Median (95% CI) CD4 count at seroconversion for a 15–29 year old woman was 607 (588–627) (non-African European), 469 (442–497) (European - African origin) and 570 (551–589) (SSA) cells/µL with respective CD4 decline during the first 4 years of 259 (228–289), 155 (110–200), and 199 (174–224) cells/µL (p<0.01).

Discussion

Despite differences in CD4 cell count evolution, death and non-TB AIDS rates were similar across study groups. It is therefore prudent to apply current ART guidelines from resource-rich countries to African populations.     

Postoperative electron-beam irradiation therapy for keloids and hypertrophic scars: retrospective study of 147 cases followed for more than 18 months

Between 1988 and 2000, 378 cases of keloids were treated in the authors' department, and 147 keloids in 129 patients were selected for this study. Keloids that occurred at a different site in the same patient and keloids that recurred later at the same site were deemed to be different keloids. Those keloids were surgically removed, and the patients were treated postoperatively with 15-Gy electron-beam irradiation and followed for more than 18 months. The therapeutic outcomes were evaluated. Statistical analysis was performed using Fisher's exact probability test or chi-square test. Recurrence occurred in two sites on 14 earlobes (14.3 percent), in two sites on 12 necks (16.7 percent), in 22 sites on 51 anterior chest walls (43.1 percent), in 13 sites in 33 scapular regions (39.4 percent), in four sites on 15 upper limbs (26.7 percent), in four sites in 11 suprapubic regions (36.4 percent), and in one site on 11 lower limbs (9.1 percent). The overall recurrence rate was 32.7 percent. Analysis of the therapeutic outcomes showed that the recurrence rates in the sites with high stretch tension, such as the chest wall, and the scapular and suprapubic regions were statistically higher than in sites without high tension, such as the neck, earlobes, and lower limbs (41.1 percent versus 13.5 percent, p = 0.0017). The results suggested that keloid sites with a high risk of recurrence should be treated with escalated radiation doses and posttreatment self-management.