Extracellular β-1,6-glucanase activity during growth of seven strains of Saccharomyces cerevisiae

Two standard strains and five local isolates of Saccharomyces cerevisiae all produced extracellular -1,6-glucanases in a growth-associated manner. Glucose at 2% (w/v) enhanced enzyme production up to 0.8 U ml^-1. Optimum activity was at pH 5.0.The authors are with the Department of Microbiology. University of Dhaka, Dhaka 1000, Bangladesh     

Comparative Analysis of Serum Zinc, Copper, Manganese, Iron, Calcium, and Magnesium Level and Complexity of Interelement Relations in Generalized Anxiety Disorder Patients

The purpose of the study was to determine the concentration of serum trace and other essential elements of generalized anxiety disorder patients and to find out the relationship between element levels and nutritional status or socioeconomic factors. The study was conducted among 50 generalized anxiety disorder patients and 51 healthy volunteers. Patients were selected and recruited in the study with the help of a clinical psychologist by random sampling. The concentrations of serum trace elements (Zn, Cu, Mn, and Fe) and other two essential elements (Ca and Mg) were determined by graphite furnace and flame atomic absorption spectroscopy. Data were analyzed by independent t test, Pearson’s correlation analysis, regression analysis, and analysis of variance. The serum concentrations of Zn, Cu, Mn, Fe, Ca, and Mg in generalized anxiety disorder patients were 1.069?±?0.40, 1.738?±?0.544, 1.374?±?0.750, 3.203?±?2.065, 108.65?±?54.455, and 21?±?4.055 mg/L, while those were 1.292?±?0.621, 0.972?±?0.427, 0.704?±?0.527, 1.605?±?1.1855, 101.849?±?17.713, and 21.521?±?3.659 mg/L in control subjects. Significantly decreased (p?<?0.05) serum Zn concentration was found in the patient group compared to the control group while serum level of Cu, Mn, and Fe was significantly (p?<?0.05) higher, but the differences of the concentration of Ca and Mg between the patient and control groups were not significant (p?>?0.05). Socioeconomic data revealed that most of the patients were in the lower middle class group and middle-aged. Mean BMI of the control group (23.63?±?3.91 kg/m²) and the patient group (23.62?±?3.77 kg/m²) was within the normal range (18.5–25.0 kg/m²). The data obtained from different interelement relations in the generalized anxiety disorder patients and control group strongly suggest that there is a disturbance in the element homeostasis. So changes in the serum trace element level in generalized anxiety disorder patients occur independently and they may provide a prognostic tool for the diagnosis and treatment of this disease.     

Serological Cross-Reaction Between O-Antigens of Shigella dysenteriae Type 4 and an Environmental Escherichia albertii Isolate

An environmental freshwater bacterial isolate, DM104, appearing as Shigella-like colonies on selective agar plates was found to show strong and specific serological cross-reactivity with Shigella dysenteriae type 4. Biochemical identification according to the analytical profile index, molecular serotyping by restriction of the amplified O-antigen gene cluster (rfb-RFLP), together with phylogenetic analysis of the 16S rRNA gene and multi-locus sequence analysis, identified the isolate as Escherichia albertii. rfb-RFLP of DM104, revealed a profile different from that of S. dysenteriae type 4. However, western blot analysis of extracted lipopolysaccharides demonstrated strong cross-reactivity with S. dysenteriae type 4 using specific monovalent antisera and a lipopolysaccharide gel banding profile similar to that of S. dysenteriae type 4. The observed O-antigen cross-reaction between an E. albertii isolate and S. dysenteriae extends our knowledge of the extent of O-antigen cross-reaction within the Escherichia/Shigella group of organisms, and offers the possibility of using DM104 and similar cross-reacting strains as shigellosis vaccine candidates.     

Is Serum Zinc Level Associated with Prediabetes and Diabetes?: A Cross-Sectional Study from Bangladesh

Aims

To determine serum zinc level and other relevant biological markers in normal, prediabetic and diabetic individuals and their association with Homeostasis Model Assessment (HOMA) parameters.

Methods

This cross-sectional study was conducted between March and December 2009. Any patient aged ≥30 years attending the medicine outpatient department of a medical university hospital in Dhaka, Bangladesh and who had a blood glucose level ordered by a physician was eligible to participate.

Results

A total of 280 participants were analysed. On fasting blood sugar results, 51% were normal, 13% had prediabetes and 36% had diabetes. Mean serum zinc level was lowest in prediabetic compared to normal and diabetic participants (mean differences were approximately 65 ppb/L and 33 ppb/L, respectively). In multiple linear regression, serum zinc level was found to be significantly lower in prediabetes than in those with normoglycemia. Beta cell function was significantly lower in prediabetes than normal participants. Adjusted linear regression for HOMA parameters did not show a statistically significant association between serum zinc level, beta cell function (P = 0.07) and insulin resistance (P = 0.08). Low serum zinc accentuated the increase in insulin resistance seen with increasing BMI.

Conclusion

Participants with prediabetes have lower zinc levels than controls and zinc is significantly associated with beta cell function and insulin resistance. Further longitudinal population based studies are warranted and controlled trials would be valuable for establishing whether zinc supplementation in prediabetes could be a useful strategy in preventing progression to Type 2 diabetes.     

Differential type I interferon induction by respiratory syncytial virus and influenza a virus in vivo

Type I interferon (IFN) induction is an immediate response to virus infection, and very high levels of these cytokines are produced when the Toll-like receptors (TLRs) expressed at high levels by plasmacytoid dendritic cells (pDCs) are triggered by viral nucleic acids. Unlike many RNA viruses, respiratory syncytial virus (RSV) does not appear to activate pDCs through their TLRs and it is not clear how this difference affects IFN-alpha/beta induction in vivo. In this study, we investigated type I IFN production triggered by RSV or influenza A virus infection of BALB/c mice and found that while both viruses induced IFN-alpha/beta production by pDCs in vitro, only influenza virus infection could stimulate type I IFN synthesis by pDCs in vivo. In situ hybridization studies demonstrated that the infected respiratory epithelium was a major source of IFN-alpha/beta in response to either infection, but in pDC-depleted animals only type I IFN induction by influenza virus was impaired.     

Survival of escherichia coli in Water Microcosm Study and Rethinking its Use as Indicator

Microbiology - We investigated the fate of Escherichia coli in natural waters, addressing survival, viable but non-culturable (VBNC) state, changes in phenotype and genomic diversification under...     

Fluoroquinolone Resistance Mechanisms of Shigella flexneri Isolated in Bangladesh

Objective

To investigate the prevalence and mechanisms of fluoroquinolone resistance in Shigella species isolated in Bangladesh and to compare with similar strains isolated in China.

Methods

A total of 3789 Shigella isolates collected from Clinical Microbiology Laboratory of icddr,b, during 2004–2010 were analyzed for antibiotic susceptibility. Analysis of plasmids, plasmid-mediated quinolone-resistance genes, PFGE, and sequencing of genes of the quinolone-resistance-determining regions (QRDR) were conducted in representative strains isolated in Bangladesh and compared with strains isolated in Zhengding, China. In addition, the role of efflux-pump was studied by using the efflux-pump inhibitor carbonyl cyanide-m-chlorophenylhydrazone (CCCP).

Results

Resistance to ciprofloxacin in Shigella species increased from 0% in 2004 to 44% in 2010 and S. flexneri was the predominant species. Of Shigella spp, ciprofloxacin resistant (Cip^R) strains were mostly found among S. flexneri (8.3%), followed by S. sonnei (1.5%). Within S. flexneri (n = 2181), 14.5% were resistance to ciprofloxacin of which serotype 2a was predominant (96%). MIC of ciprofloxacin, norfloxacin, and ofloxacin were 6–32 mg/L, 8–32 mg/L, and 8–24 mg/L, respectively in S. flexneri 2a isolates. Sequencing of QRDR genes of resistant isolates showed double mutations in gyrA gene (Ser⁸³Leu, Asp⁸⁷Asn/Gly) and single mutation in parC gene (Ser⁸⁰Ile). A difference in amino acid substitution at position 87 was found between strains isolated in Bangladesh (Asp⁸⁷Asn) and China (Asp⁸⁷Gly) except for one. A novel mutation at position 211 (His→Tyr) in gyrA gene was detected only in the Bangladeshi strains. Susceptibility to ciprofloxacin was increased by the presence of CCCP indicating the involvement of energy dependent active efflux pumps. A single PFGE type was found in isolates from Bangladesh and China suggesting their genetic relatedness.

Conclusions

Emergence of fluoroquinolone resistance in Shigella undermines a major challenge in current treatment strategies which needs to be followed up by using empirical therapeutic strategies.