Membrane Fractionation of Liquors from Lignin-First Biorefining.

For the utilization of each lignin fraction in the lignin liquors, the development of separation strategies to fractionate the lignin streams by molecular weight ranges constitutes a timely challenge to be tackled. Herein, membrane filtration was applied to the refining of lignin streams obtained from a lignin-first biorefining process based on H-transfer reactions catalyzed by Raney Ni, by using 2-PrOH as a part of the lignin extraction liquor and as an H-donor. A two-stage membrane cascade was considered to separate and concentrate the monophenol-rich fraction from the liquor. Building on the results, an economic evaluation of the potential of membrane filtration for the refining of lignin streams was undertaken. In this proof-of-concept report, a detailed analysis is presented of future developments in the performance required for the utilization of membrane filtration for lignin refining and, more aspiringly, solvent reclamation.

Histological pattern of paediatric renal diseases in northern Pakistan.

OBJECTIVE: To determine histological spectrum of renal diseases among the paediatric population in the province Khyber Pukhtunkhwa, and to note any change in histological pattern with age and serum creatinine. METHODS: This is a retrospective analysis of 415 paediatric renal biopsies performed at the department of nephrology, Lady Reading Hospital Peshawar from 1998-2005. Children from 3 to 15 years of age, having renal disease and indications for biopsy, underwent ultrasound guided percutaneous renal biopsy. Indications included nephrotic syndrome, nephritic/nephrotic syndrome with renal insufficiency and nephrotic syndrome with steroid resistance. Patients with acute or chronic renal failure were not included. The specimens were examined without immunoflorescence, under light microscopy using different staining techniques, Results were analyzed for different age groups, serum creatinine levels and for both male and females with renal disease. RESULTS: The overall male to female ratio in the study was 1.6: 1. Nephrotic syndrome was most common indication for renal biopsy in 50% of the cases, followed by renal insufficiency (26%) and steroid resistance (24%). In children with primary glomerulonephritis, minimal change disease (MCD) was found to be the most common histological pattern (24.09%), followed by focal segmental glomerulosclerosis (FSGS), 18.30%; mesangioproliferative glomerulonephritis (GN) (MsePGN), 17.83%; mesangiocapillary GN (MPGN), 11.08%; post streptococcal proliferative GN (Post. strep GN), 10.60%; membranous GN (MGN), 4.82%; crescentic GN (Cres.GN), 4.34%. Among children with secondary GN, chronic sclerosing GN was found to be most common (1.93%), followed by chronic tubulo interstitial nephritis (Chr.TIN), 1.69% and hypertensive nephropathy (H.Neph), 1.69%; Renal Amyloidosis, 0.96% and Lupus Nephritis III, 0.96%; acute tubular necrosis (ATN), 0.72%; Alport's Syndrome (0.48%). Overall, MCD was the most common histological pattern in all age groups and among children with serum creatinine < 1.2 mg/dll. However, that with serum creatinine between 1.3 to 3 mg/dl, MsePGN was found to be more common. Age turned out to be significant factor, in contrast to serum creatinine, in determining various histological patterns. CONCLUSION: This study highlighted the histological patterns of renal disease among pediatric population from northern part of Pakistan. MCD was on the top followed by FSGS, but frequency of MCD was less than cited in earlier studies.

Studies on diarrheagenic Escherichia coli isolated from children with diarrhea in Myanmar.

Escherichia coli isolates from 217 children in Myanmar with diarrhea were investigated for the presence of virulence genes related to diarrhea by colony hybridization and PCR. The genes examined were lt, stI, stII, stx1, stx2, eae, bfp, pCVD (which is the representative gene of plasmid of pCVD of EAEC), and ial (which is invasion-associated locus of the invasion plasmid found in EIEC). Isolates from 47 of 217 children (21.7%) possessed virulence genes characteristic of diarrheagenic E. coli. No instance was found of co-existence of different E. coli strains with different virulence genes in the same patient. Diarrheagenic E. coli are currently classified into five categories based on their virulence markers: ETEC, EHEC, EPEC, EAEC, and EIEC. Of the 47 isolates examined, 30 were EAEC, 12 were EPEC and 5 were ETEC. Susceptibility tests for antimicrobial agents showed that almost all diarrheagenic isolates were resistant to penicillin, tetracycline and streptomycin. However, the majority of strains were sensitive to cephalexin, nalidixic acid and norfloxacin. In particular, 42 of the 47 isolates were sensitive to norfloxacin, which is a fluoroquinolone. This study shows EAEC and EPEC are responsible for sporadic diarrhea in Myanmar and fluoroquinolones appear to be effective in the treatment of these patients.

Presence of LuxS/AI-2 based quorum-sensing system in Vibrio mimicus : luxO controls protease activity.

Presence of the quorum-sensing regulation system in Vibrio mimicus was investigated. The culture supernatants of V. mimicus strains were found to possess AI-2 autoinducer like activity, and the strains were found to harbor the genes which are homologous to luxS, luxO, and luxR of V. harveyi. These genes of V. harveyi have been shown to be important components of V. harveyi-like quorum-sensing system. The luxO gene homologue known to encode LuxO, the central component of the regulation system, was disrupted, and effects on protease and hemolysin activity were studied. Disruption of luxO gene resulted in the increased protease activity, but the hemolysin activity did not vary considerably.

Sexually transmitted infections among brothel-based sex workers in bangladesh: high prevalence of asymptomatic infection.

UNLABELLED: OBJECTIVE AND GOAL: The goal of this study was to study the prevalence of sexually transmitted infections (STIs)/reproductive tract infections (RTIs) among brothel-based sex workers (SWs) in Bangladesh. STUDY: A cross-sectional study was conducted among SWs in 4 randomly selected brothels. A sociodemographic and behavioral survey and pelvic examination was conducted. Specimens including endocervical swab, high vaginal swab, and blood were collected and were examined for Neisseria gonorrhoeae, Chlamydia trachomatis, Trichomonas vaginalis, bacterial vaginosis candidiasis, and syphilis. RESULTS: A total of 439 SWs were enrolled and 49.6% had genital symptoms. Among all SWs, 17.5% were positive for N. gonorrhoeae; 15.5% for C. trachomatis; 7.5% for T. vaginalis, and 6.6% had active syphilis. A total of 67.4% SWs were positive for at least 1 cervical and/or vaginal infection. CONCLUSION: The prevalence of STIs/RTIs among SWs in brothels in Bangladesh is high. An intervention strategy addressing both symptomatic and asymptomatic infections and periodic screening of SWs for RTIs/STIs is essential for successful HIV and STIs prevention programs.

Regulation system for protease production in Vibrio vulnificus.

Vibrio vulnificus is a causative agent of serious food-borne diseases in humans related to consumption of raw seafoods. This human pathogen secretes a metalloprotease (VVP) that evokes enhancement of the vascular permeability and disruption of the capillaries. Production of microbial proteases is generally induced at early stationary phase of its growth. This cell density dependent regulation of VVP production in V. vulnificus known to be the quorum-sensing. When V. vulnificus was cultivated in Luria-Bertani (LB) medium, accumulation of the autoinducer, the signal molecule operating the quorum-sensing system, was detected. Moreover, expression of the vvp gene encoding VVP was found to be closely related with expression of the luxS gene that encode the synthase of the autoinducer precursor (luxS). These findings may indicate VVP production is controlled by the quorum-sensing system in LB medium. Furthermore, this system functioned more effectively at 26 degrees C than at 37 degrees C. When incubated at 37 degrees C in human serum supplemented with ferric chloride, production of VVP and expression of vvp increased in proportion to the concentration of ferric ion; whereas, expression of luxS was not increased. This suggests that VVP production in human serum containing ferric ion may be regulated mainly by the system other than the quorum-sensing system.

Comparison of mismatch amplification mutation assay with DNA sequencing for characterization of fluoroquinolone resistance in Neisseria gonorrhoeae.

A mismatch amplification mutation assay (MAMA) was developed for identification of point mutations in quinolone resistance-determining region (QRDR) of gyrA at codons 91 and 95. MAMA PCR was used to detect mutations at codons 91 and 95 of gyrA in 117 Neisseria gonorrhoeae isolates (with ciprofloxacin MICs of 0.004 to >32 microg/ml) from Bangladesh during 1997 to 2001. The QRDR regions of the gyrA genes from 31 randomly selected isolates were sequenced, and the results were compared with those of MAMA PCR. Using mismatch PCR, a mutation at Ser91 could be detected in all 27 (resistant and intermediate) isolates, and an Asp95-to-Gly95 mutation could be detected in all 15 isolates, as detected by sequencing. MAMA PCR offers a simple, inexpensive, rapid, and easier alternative for detection of point mutations in fluoroquinolone resistance in N. gonorrhoeae.

Epidemiology and etiology of sexually transmitted infection among hotel-based sex workers in Dhaka, Bangladesh.

The prevalence of sexually transmitted infections (STIs) and reproductive tract infections (RTIs) among hotel-based sex workers (HBSWs) in Dhaka, Bangladesh, was studied. A total of 400 HBSWs were enrolled in the study during April to July 2002. Endocervical swabs, high vaginal swabs, and blood samples from 400 HBSWs were examined for Neisseria gonorrhoeae (by culture), Chlamydia trachomatis (by PCR), Trichomonas vaginalis (by microscopy), antibody to Treponema pallidum (by both rapid plasma reagin and Treponema pallidum hemagglutination tests), and antibody to herpes simplex virus type 2 (HSV-2) (by enzyme-linked immunosorbent assay). Sociodemographic information as well as gynecological and obstetric information was collected. Among the HBSWs, 228 women (57%) were symptomatic and 172 (43%) were asymptomatic, 35.8% were positive for N. gonorrhoeae, 43.5% were positive for C. trachomatis, and 4.3% were positive for T. vaginalis. A total of 8.5% had syphilis, 34.5% were positive for HSV-2, and 86.8% were positive for at least one RTI or STI. There was no significant difference between the prevalences of STIs among the symptomatic and asymptomatic HBSWs. These data suggested a high prevalence of STIs, particularly gonorrhea and chlamydia, among HBSWs in Dhaka.

Antimicrobial susceptibility of Neisseria gonorrhoeae isolated in Bangladesh (1997 to 1999): rapid shift to fluoroquinolone resistance.

Periodic monitoring of antimicrobial susceptibility of Neisseria gonorrhoeae is essential for early detection of emergence of drug resistance. A total of 343 gonococcal strains isolated from high-risk and general populations in Bangladesh from 1997 to 1999 were studied. The MICs of penicillin, tetracycline, ciprofloxacin, ceftriaxone, and spectinomycin for the isolates were determined by the agar dilution method. Of the isolates from 1997, 9% were resistant (MIC >or= 1.0 microg/ml) to ciprofloxacin, while 41 and 49% of the isolates from 1998 and 1999, respectively, were resistant to ciprofloxacin. Of the N. gonorrhoeae isolates from 1998 and 1999, 1.2 and 3.6%, respectively, both were penicillinase producing and displayed plasmid-mediated tetracycline resistance.