Chemical structures and biological activities of rhamnolipids produced by Pseudomonas aeruginosa B189 isolated from milk factory waste

The aim of this work was to study chemical structures and biological activities of rhamnolipids produced by Pseudomonas aeruginosa B189 isolated from milk factory waste. The culture produced two biosurfactants, a and b, which showed strong activity and were identified as L-rhamnopyranosyl-L-rhamnopyranosyl-beta-hydroxydecanoyl-beta-hydroxydecanoate or Rha-Rha-C10-C10 and L-rhamnopyranosyl-L-rhamnopyranosyl-beta-hydroxydecanoyl-beta-hydroxydodecanoate or Rha-Rha-C10-C12, respectively. Both compounds exhibited higher surfactant activities tested by the drop collapse test than several artificial surfactants such as SDS and Tween 80. Rhamnolipid a showed significant antiproliferative activity against human breast cancer cell line (MCF-7) at minimum inhibitory concentration (MIC) at 6.25 microg/mL while rhamnolipid b showed MIC against insect cell line C6/36 at 50 microg/mL.     

Identification and cultivation of photosynthetic bacteria in wastewater from a concentrated latex processing factory

Ten strains of purple non-sulfur photosynthetic bacteria, isolated from wastewater produced by a concentrated latex processing factory, were cultivated in a wastewater medium without supplementation. After 40 h cultivation, one strain SS51, decreased the COD content of the wastewater by 34%. Optimal ratio of mixed-cultivation between SS51 and SY40 was 14:7 (ml/ml), and the COD content of the wastewater was decreased by 57%. Both strains were identified as Rubrivivax gelatinosus.     

Longitudinal in vitro surveillance of Plasmodium falciparum sensitivity to common anti-malarials in Thailand between 1994 and 2010

ABSTRACT: BACKGROUND: Drug and multidrug-resistant Plasmodium falciparum malaria has existed in Thailand for several decades. Furthermore, Thailand serves as a sentinel for drug-resistant malaria within the Greater Mekong sub-region. However, the drug resistance situation is highly dynamic, changing quickly over time. Here parasite in vitro drug sensitivity is reported for artemisinin derivatives, mefloquine, chloroquine and quinine, across Thailand. METHODS: Blood was drawn from patients infected with P. falciparum in seven sentinel provinces along Thai international borders with Cambodia, Myanmar, Laos, and Malaysia. In vitro parasite sensitivity was tested using the World Health Organization's microtest (mark III) (between 1994 and 2002) and the histidine-rich protein-2 (HRP2)-based enzyme-linked immunosorbent assay (in 2010). Following World Health Organization protocol, at least 30 isolates were collected for each province and year represented in this study. Where possible, t-tests were used to test for significant differences. RESULTS: There appears to be little variation across study sites with regard to parasite sensitivity to chloroquine. Quinine resistance appears to have been rising prior to 1997, but has subsequently decreased. Mefloquine sensitivity appears high across the provinces, especially along the north-western border with Myanmar and the eastern border with Cambodia. Finally, the data suggest that parasite sensitivity to artemisinin and its derivatives is significantly higher in provinces along the north-western border with Myanmar. CONCLUSIONS: Parasite sensitivity to anti-malarials in Thailand is highly variable over time and largely mirrors official drug use policy. The findings with regard to reduced sensitivity to artemisinin derivatives are supported by recent reports of reduced parasite clearance associated with artemisinin. This trend is alarming since artemisinin is considered the last defence against malaria. Continued surveillance in Thailand, along with increased collaboration and surveillance across the entire Greater Mekong sub-region, is clearly warranted.     

Assessment of Oral Fluid HIV Test Performance in an HIV Pre-Exposure Prophylaxis Trial in Bangkok,Thailand

Background

Rapid easy-to-use HIV tests offer opportunities to increase HIV testing among populations at risk of infection. We used the OraQuick Rapid HIV-1/2 antibody test (OraQuick) in the Bangkok Tenofovir Study, an HIV pre-exposure prophylaxis trial among people who inject drugs.

Methods

The Bangkok Tenofovir Study was a randomized, double-blind, placebo-controlled trial. We tested participants’ oral fluid for HIV using OraQuick monthly and blood using a nucleic-acid amplification test (NAAT) every 3 months. We used Kaplan-Meier methods to estimate the duration from a positive HIV NAAT until the mid-point between the last non-reactive and first reactive oral fluid test and proportional hazards to examine factors associated with the time until the test was reactive.

Results

We screened 3678 people for HIV using OraQuick. Among 447 with reactive results, 436 (97.5%) were confirmed HIV-infected, 10 (2.2%) HIV-uninfected, and one (0.2%) had indeterminate results. Two participants with non-reactive OraQuick results were, in fact, HIV-infected at screening yielding 99.5% sensitivity, 99.7% specificity, a 97.8% positive predictive value, and a 99.9% negative predictive value. Participants receiving tenofovir took longer to develop a reactive OraQuick (191.8 days) than participants receiving placebo (16.8 days) (p = 0.02) and participants infected with HIV CRF01_AE developed a reactive OraQuick earlier than participants infected with other subtypes (p = 0.04).

Discussion

The oral fluid HIV test performed well at screening, suggesting it can be used when rapid results and non-invasive tools are preferred. However, participants receiving tenofovir took longer to develop a reactive oral fluid test result than those receiving placebo. Thus, among people using pre-exposure prophylaxis, a blood-based HIV test may be an appropriate choice.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00119106","term_id":"NCT00119106"}}NCT00119106.     

Molecular cloning and expression analysis of the interferon-γ-inducible lysosomal thiol reductase gene from the shrimp <Emphasis Type="Italic">Penaeus monodon</Emphasis>

The interferon-γ-inducible lysosomal thiol reductase enzymes (GILT) have been shown to play an important role in the processing of exogenous antigens by catalyzing disulfide bond reduction, that facilitates unfolding of the native protein antigen to simplify further cleavage by cellular proteases. In this study a Penaeus monodon GILT (PmGILT) gene was isolated from an EST library of white spot syndrome virus (WSSV)-infected P. monodon. The full-length cDNA of the PmGILT gene was 780 bp and contained an open reading frame of 657 bp that encoded 218 amino acid residues with a predicted protein molecular weight of 24 kDa. The deduced amino acid sequence of PmGILT contains an active site CXXS motif, a GILT signature sequence (CQHGX₂ECX₂NX₄C) and 10 conserved cysteines together with other signature characteristics of GILT proteins. RT-PCR analysis showed that the PmGILT mRNA expression level was clearly up-regulated in the lymphoid organ of both the LPS-induced and WSSV-infected shrimp, compared to normal shrimp. In response to WSSV infection, the penaeid shrimp JAK/STAT pathway is reported to play an important role in the lymphoid organ. We hypothesize that this activated STAT may stimulate GILT expression so that it can be involved in the shrimp immune response system.     

Functional analysis of two polygalacturonase genes in Apolygus lucorum associated with eliciting plant injury using RNA interference

Salivary enzymes of many piercing–sucking insects lead to host plant injury. The salivary enzymes, polygalacturonase (PGs), act in insect feeding. PG family genes have been cloned from the mirid bug Apolygus lucorum, a pest of cotton and other host crops in China. We investigated the function of two PG genes that are highly expressed in A. lucorum nymphs (PG3‐4) and adults (PG3‐5), using siRNA injection‐based RNA interference (RNAi). Accumulation of mRNA encoding both genes and their cognate proteins was significantly reduced (>60%) in experimental compared control green fluorescent protein (GFP) siRNA‐treated mirids at 48 h post injection. Injury levels of cotton buds were also significantly reduced after injecting saliva isolated from PG3‐4 and PG3‐5 siRNA‐treated A. lucorum. These results demonstrate that these two PG act in A. lucorum elicitation of plant injury.     

In-vitro assessment of probiotic potential of <Emphasis Type="Italic">Lactobacillus plantarum</Emphasis> WU-P19 isolated from a traditional fermented herb

Samples of fermented herbs were used to isolate lactic acid bacteria (LAB). Of a total of 19 isolates, eight were resistant both to gastric acid and bile salts (glycocholic acid, GCA; taurocholic acid, TCA; glycodeoxycholic acid, GDCA; and taurodeoxycholic acid, TDCA). Most isolates exhibited a pH-dependent surface hydrophobicity: a pH of 4 conferred a greater hydrophobicity compared to a pH of 7. Based on the hydrophobicity characteristics, the LAB isolate WU-P19 from the traditional fermented herb Oroxylum indicum was selected for further study. WU-P19 was identified as Lactobacillus plantarum WU-P19. The presence of bile salts GCA and GDCA in the culture medium induced production of the relevant bile salt hydrolase. Relative to controls, the presence of the bile salts in the culture medium affected the carbon and nitrogen contents of the cells and their hydrophobicity. Cells grown in a medium free of bile salts were morphologically different to cells grown in the presence of GCA and GDCA. WU-P19 was resistant to several antibiotics. It produced β-galactosidase and inhibited growth of the tested pathogenic bacteria at various levels. In vitro, L. plantarum WU-P19 adapted well to conditions typical of the various zones of the human gastrointestinal tract. In view of the promising results, in vivo evaluations are planned for the isolate WU-P19.     

Evolution of Genetic Polymorphisms of Plasmodium falciparum Merozoite Surface Protein (PfMSP) in Thailand

Plasmodium falciparum malaria is a major public health problem in Thailand due to the emergence of multidrug resistance. The understanding of genetic diversity of malaria parasites is essential for developing effective drugs and vaccines. The genetic diversity of the merozoite surface protein-1 (PfMSP-1) and merozoite surface protein-2 (PfMSP-2) genes was investigated in a total of 145 P. falciparum isolates collected from Mae Sot District, Tak Province, Thailand during 3 different periods (1997-1999, 2005-2007, and 2009-2010). Analysis of genetic polymorphisms was performed to track the evolution of genetic change of P. falciparum using PCR. Both individual genes and their combination patterns showed marked genetic diversity during the 3 study periods. The results strongly support that P. falciparum isolates in Thailand are markedly diverse and patterns changed with time. These 2 polymorphic genes could be used as molecular markers to detect multiple clone infections and differentiate recrudescence from reinfection in P. falciparum isolates in Thailand.     

Searching for Sharp Drops in the Incidence of Pandemic A/H1N1 Influenza by Single Year of Age

Background

During the 2009 H1N1 pandemic (pH1N1), morbidity and mortality sparing was observed among the elderly population; it was hypothesized that this age group benefited from immunity to pH1N1 due to cross-reactive antibodies generated from prior infection with antigenically similar influenza viruses. Evidence from serologic studies and genetic similarities between pH1N1 and historical influenza viruses suggest that the incidence of pH1N1 cases should drop markedly in age cohorts born prior to the disappearance of H1N1 in 1957, namely those at least 52–53 years old in 2009, but the precise range of ages affected has not been delineated.

Methods and Findings

To test for any age-associated discontinuities in pH1N1 incidence, we aggregated laboratory-confirmed pH1N1 case data from 8 jurisdictions in 7 countries, stratified by single year of age, sex (when available), and hospitalization status. Using single year of age population denominators, we generated smoothed curves of the weighted risk ratio of pH1N1 incidence, and looked for sharp drops at varying age bandwidths, defined as a significantly negative second derivative. Analyses stratified by hospitalization status and sex were used to test alternative explanations for observed discontinuities. We found that the risk of laboratory-confirmed infection with pH1N1 declines with age, but that there was a statistically significant leveling off or increase in risk from about 45 to 50 years of age, after which a sharp drop in risk occurs until the late fifties. This trend was more pronounced in hospitalized cases and in women and was independent of the choice in smoothing parameters. The age range at which the decline in risk accelerates corresponds to the cohort born between 1951–1959 (hospitalized) and 1953–1960 (not hospitalized).

Conclusions

The reduced incidence of pH1N1 disease in older individuals shows a detailed age-specific pattern consistent with protection conferred by exposure to influenza A/H1N1 viruses circulating before 1957.