Prevalence of zoonotic (brugian) filariasis in Asia: A proportional meta-analysis

Lymphatic filariasis is a public health problem and targeted for global elimination. WHO recommends mass drug administration to interrupt transmission of the parasites involved. There are concerns that transmission interruption may be difficult in areas of zoonotic filarial infections. This study aimed to estimate the pooled prevalence of zoonotic brugian filariasis, and to compare the pooled prevalence of brugian filariasis in human and animal populations in the same area based on available studies. A comprehensive literature search was conducted in health-related electronic databases (PubMed, Ovid MEDLINE, Index Medicus, google scholar). A random-effect meta-analysis of the pooled overall prevalence of filariasis in animal populations was conducted. Sixteen studies from four different Asian countries were identified. Studies were conducted most frequently in Thailand (n = 7), followed by Malaysia (n = 5), India (n = 3), and Sri Lanka (n = 1). Regardless of animal group, the pooled overall prevalence of animal Brugia infections was 13% (95%CI: 7-21%, I2:98%, 16 studies). On stratification, the pooled overall prevalence in the animal population was 19% (95%CI: 1-50%, I2: 99%, 3 studies) in India, 8% (95%CI: 2-7%, I2: 97%, 5 studies) in Malaysia, and 13% (95%CI: 7-20%, I2: 94%, 7 studies) in Thailand. The prevalence in the animal population was 17% (95%CI: 13-21%, 1 study) in Sri Lanka. The pooled overall prevalence of Brugia malayi was 13% (95%CI: 7-21%, I2:98%, 12 studies), while for Brugia pahangi this was 12% (95%CI: 7-19%, I2:86%, 7 studies). Regardless of animal group, geographic area, or diagnostic test, the prevalence of B. malayi was consistently high. On stratification by animal category, the pooled overall prevalence was 10% (95%CI: 6-14%, I2:92%, 13 studies) in cats, 12% (95%CI: 2-28%, I2: 99%, 6 studies) in dogs, and 55% (95%CI: 47-63%, 1 study) in leaf-eating monkeys. The findings show the extent of zoonotic Brugiainfections in domestic cats and dogs, suggesting that these animals are potential reservoirs for human brugian filariasis in the study countries. To substantiate this with more accuracy, future well designed whole genomic sequencing of individual mf collected from humans and B. malayi infected animals in the same area are needed.

Loop-mediated isothermal amplification (LAMP) test in the detection of uncomplicated malaria in pregnancy: a meta-analysis of diagnostic accuracy

BACKGROUND

Due to relatively low malaria parasitaemia in pregnancy, an appropriate field test that can adequately detect infections in pregnant women presenting with illness or for malaria screening during antenatal care is crucially important. The objective was to evaluate the diagnostic accuracy of loop-mediated isothermal amplification (LAMP) for the detection of uncomplicated malaria in pregnancy.

METHODS

This was a meta-analysis of diagnostic accuracy. Relevant studies that assessed the diagnostic performance of LAMP for the detection of malaria in pregnancy were searched in health-related electronic databases including PubMed, Ovid, and Google Scholar. The methodological quality of the studies included was evaluated using the QUADAS-2 tool.

RESULTS

Of the 372 studies identified, eight studies involving 2999 pregnant women in five endemic countries that assessed the accuracy of LAMP were identified. With three types of PCR as reference tests, the pooled sensitivity of LAMP was 91% (95%CI 67-98%) and pooled specificity was 99% (95%CI 83-100%, 4 studies), and the negative likelihood ratio was 9% (2-40%). Caution is needed in the interpretation as there was substantial between-study heterogeneity (I²: 80%), and a low probability that a person without infection is tested negative. With microscopy as a reference, the pooled sensitivity of LAMP was 95% (95%CI 26-100%) and pooled specificity was 100% (95%CI 94-100%, 4 studies). There was a wide range of sensitivity and substantial between-study heterogeneity (I²: 83.5-98.4%). To investigate the source of heterogeneity, a meta-regression analysis was performed with covariates. Of these potential confounding factors, reference test (p: 0.03) and study design (p:0.03) had affected the diagnostic accuracy of LAMP in malaria in pregnancy. Overall, there was a low certainty of the evidence in accuracy estimates.

CONCLUSION

The findings suggest that LAMP is more sensitive than traditional tests used at facilities, but the utility of detecting and treating these low-density infections is not well understood. Due to the limited number of studies with bias in their methodological quality, variation in the study design, and different types of reference tests further research is likely to change the estimate. Well-conceived large prospective studies with blinding of the index test results are recommenced.

Dengue fever and insecticide resistance in Aedes mosquitoes in Southeast Asia: a review

Dengue fever is the most important mosquito-borne viral disease in Southeast Asia. Insecticides remain the most effective vector control approach for Aedes mosquitoes. Four main classes of insecticides are widely used for mosquito control: organochlorines, organophosphates, pyrethroids and carbamates. Here, we review the distribution of dengue fever from 2000 to 2020 and its associated mortality in Southeast Asian countries, and we gather evidence on the trend of insecticide resistance and its distribution in these countries since 2000, summarising the mechanisms involved. The prevalence of resistance to these insecticides is increasing in Southeast Asia, and the mechanisms of resistance are reported to be associated with target site mutations, metabolic detoxification, reduced penetration of insecticides via the mosquito cuticle and behavioural changes of mosquitoes. Continuous monitoring of the status of resistance and searching for alternative control measures will be critical for minimising any unpredicted outbreaks and improving public health. This review also provides improved insights into the specific use of insecticides for effective control of mosquitoes in these dengue endemic countries.

A25 THE RISING GLOBAL INCIDENCE OF PEDIATRIC INFLAMMATORY BOWEL DISEASE: A SYSTEMATIC REVIEW OF POPULATION-BASED STUDIES

Background

The incidence of inflammatory bowel disease (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), is increasing internationally, particularly in developing nations where rates were historically low. Previous reports of the incidence and prevalence of pediatric-onset IBD have identified a paucity of population-based studies.

Aims

We reviewed the global trends in incidence of pediatric IBD using evidence from population-based studies.

Methods

(PROSPERO CRD42019125193) We systematically reviewed studies indexed in MEDLINE, EMBASE, Airiti Library, and SciELO from 01/2010-02/2020 to identify population-based studies reporting the incidence of pediatric-onset IBD, CD, and UC. Included studies combined childhood and adolescent-onset IBD (onset <21y). Changes in incidence since 2000 were plotted by continent, with data from 2000–09 provided by our previous systematic review1. To depict trends, multiple times points reported in single studies were connected on graphs. When incidence was reported as an aggregated estimate over a range of years, data was plotted using the midpoint of the interval.

Results

Of 8096 abstracts screened, 74 studies described the incidence of IBD, CD, or UC in 33 countries (Figure panel A). The incidence of pediatric-onset IBD is highest in Northern Europe and North America, and lowest in Southern Europe, Asia, and the Middle East. This geographical distribution is similar in UC, while incidence of pediatric-onset CD is highest in North America and Northern Europe, followed by Australia. Trends in incidence over time, stratified by continent, are reported in Figure, panel B. Significantly increasing incidence of IBD, CD, and/or UC was reported in China, Bahrain, Canada, New Zealand, Australia, Singapore, Saudi Arabia, and most European countries. Very Early Onset (VEO) IBD significantly increased in Canada, however Saudi Arabia reported decreasing incidence of VEO-CD but stable incidence of VEO-UC.

Conclusions

Conclusion: Incidence of pediatric-onset IBD are highest in Northern Europe and North American and are increasing globally. There remains a paucity of studies from many parts of the world on the incidence pediatric IBD. Further research is needed to understand the pathogenesis of the rising incidence of pediatric IBD, including work to understand the genetic, environmental, immunological and microbiome alterations leading to the increasing rates in children.

References: 1Benchimol, Fortinsky et al. Inflamm Bowel Dis 2011;17:423–39.

Funding Agencies

None

Loop-mediated isothermal amplification (LAMP) test for diagnosis of uncomplicated malaria in endemic areas: a meta-analysis of diagnostic test accuracy

Background

The global malaria decline has stalled and only a few countries are pushing towards pre-elimination. The aim of the malaria elimination phase is interruption of local transmission of a specified malaria parasite in a defined geographical area. New and improved screening tools and strategies are required for detection and management of very low-density parasitaemia in the field. The objective of this study was to synthesize evidence on the diagnostic accuracy of loop-mediated isothermal amplification (LAMP) test for the detection of malaria parasites among people living in endemic areas.

Methods

This study adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis for Diagnostic Test Accuracy (PRISMA-DTA) guideline. Relevant studies in the health-related electronic databases were searched. According to the criteria set for this study, eligible studies were identified. The quality of included studies was evaluated with the use of a quality assessment checklist. A summary performance estimates such as pooled sensitivity and specificity were stratified by type of LAMP. Bivariate model for data analyses was applied. Summary receiver operating characteristics plots were created to display the results of individual studies in a receiver operating characteristics space. Meta-regression analysis was performed to investigate the sources of heterogeneity among individual studies.

Results

Twenty-seven studies across 17 endemic countries were identified. The vast majority of studies were with unclear risk of bias in the selection of index test. Overall, the pooled test performances were high for Pan LAMP (sensitivity: 0.95, 95% CI 0.91 to 0.97; specificity: 0.98, 95% CI 0.95 to 0.99), Plasmodium falciparum (Pf) LAMP (sensitivity: 0.96, 95% CI 0.94 to 0.98; specificity: 0.99, 95% CI 0.96 to 1.00) or for Plasmodium vivax (Pv) LAMP from 6 studies (sensitivity: 0.98, 95% CI 0.92 to 0.99; specificity: 0.99, 95% CI 0.72 to 1.00). The area under the curve for Pan LAMP (0.99, 95% CI 0.98–1.00), Pf LAMP (0.99, 95% CI 0.97–0.99) and Pv LAMP was (1.00, 95% CI 0.98–1.00) indicated that the diagnostic performance of these tests were within the excellent accuracy range. Meta-regression analysis showed that sample size had the greatest impact on test performance, among other factors.

Conclusions

The current findings suggest that LAMP-based assays are appropriate for detecting low-level malaria parasite infections in the field and would become valuable tools for malaria control and elimination programmes. Future well-designed larger sample studies on LAMP assessment in passive and active malaria surveillances that use PCR as the reference standard and provide sufficient data to construct 2 × 2 diagnostic table are needed.

Association between long-term exposure to ambient air pollution and prevalence of diabetes mellitus among Malaysian adults

Background

Malaysia has the highest rate of diabetes mellitus (DM) in the Southeast Asian region, and has ongoing air pollution and periodic haze exposure.

Methods

Diabetes data were derived from the Malaysian National Health and Morbidity Surveys conducted in 2006, 2011 and 2015. The air pollution data (NO_x, NO₂, SO₂, O₃ and PM₁₀) were obtained from the Department of Environment Malaysia. Using multiple logistic and linear regression models, the association between long-term exposure to these pollutants and prevalence of diabetes among Malaysian adults was evaluated.

Results

The PM₁₀ concentration decreased from 2006 to 2014, followed by an increase in 2015. Levels of NO_x decreased while O₃ increased annually. The air pollutant levels based on individual modelled air pollution exposure as measured by the nearest monitoring station were higher than the annual averages of the five pollutants present in the ambient air. The prevalence of overall diabetes increased from 11.4% in 2006 to 21.2% in 2015. The prevalence of known diabetes, underdiagnosed diabetes, overweight and obesity also increased over these years. There were significant positive effect estimates of known diabetes at 1.125 (95% CI, 1.042, 1.213) for PM₁₀, 1.553 (95% CI, 1.328, 1.816) for O₃, 1.271 (95% CI, 1.088, 1.486) for SO₂, 1.124 (95% CI, 1.048, 1.207) for NO₂, and 1.087 (95% CI, 1.024, 1.153) for NO_x for NHMS 2006. The adjusted annual average levels of PM₁₀ [1.187 (95% CI, 1.088, 1.294)], O₃ [1.701 (95% CI, 1.387, 2.086)], NO₂ [1.120 (95% CI, 1.026, 1.222)] and NO_x [1.110 (95% CI, 1.028, 1.199)] increased significantly from NHMS 2006 to NHMS 2011 for overall diabetes. This was followed by a significant decreasing trend from NHMS 2011 to 2015 [0.911 for NO₂, and 0.910 for NO_x].

Conclusion

The findings of this study suggest that long-term exposure to O₃ is an important associated factor of underdiagnosed DM risk in Malaysia. PM₁₀, NO₂ and NO_x may have mixed effect estimates towards the risk of DM, and their roles should be further investigated with other interaction models. Policy and intervention measures should be taken to reduce air pollution in Malaysia.

Gene expression changes in human bronchial epithelial cells (BEAS-2B) and human pulmonary alveolar epithelial cells (HPAEpiC) after interaction with Cladosporium sphaerospermum

Cladosporium is one of the most abundant spore. Fungi of this genus can cause respiratory allergy and intrabronchial lesion. We studied the differential expression of host genes after the interaction of Cladosporium sphaerospermum conidia with Human Bronchial Epithelial Cells (BEAS-2B) and Human Pulmonary Alveolar Epithelial Cells (HPAEpiC). C. sphaerospermum conidia were harvested and co-cultured with BEAS-2B cells or HPAEpiC cells for 48 hours respectively. This culture duration was chosen as it was associated with high germination rate. RNA was extracted from two biological replicates per treatment. RNA of BEAS-2B cells was used to assess changes in gene expression using AffymetrixGeneChip® Human Transcriptome Array 2.0. After co-culture with Cladosporium spores, 68 individual genes were found differentially expressed (P ≤ 0.05) and up-regulated ≥ 1.5 folds while 75 genes were found differentially expressed at ≤ -1.5 folds compared with controls. Reverse transcription and qPCR were performed on the RNA collected from both BEAS-2B cells and HPAEpiC cells to validate the microarray results with 7 genes. Based on the findings, infected pulmonary epithelial cells exhibited an increase in cell death-related genes and genes associated with innate immunity.

Efficacy of antimalarial drugs for treatment of uncomplicated falciparum malaria in Asian region: A network meta-analysis

BACKGROUND

The WHO recommends artemisinin-based combination therapies (ACTs) for the treatment of uncomplicated falciparum malaria. Hence, monitoring the efficacy of antimalarial drugs is a key component of malaria control and elimination. The published randomized trials that assessed comparisons of ACTs for treating uncomplicated falciparum malaria reported conflicting results in treatment efficacy. A network meta-analysis is an extension of pairwise meta-analysis that can synthesize evidence simultaneously from both direct and indirect treatment comparisons. The objective was to synthesize evidence on the comparative efficacy of antimalarial drugs for treatment of uncomplicated falciparum malaria in Asian region.

METHODS

Relevant randomized trials that assessed efficacy of antimalarial drugs for patients having uncomplicated falciparum malaria in Asian region were searched in health-related databases. We evaluated the methodological quality of the included studies with the Cochrane risk of bias tool. Main outcome was treatment success at day 28 as determined by the absence of parasiteamia. We performed network meta-analysis of the interventions in the trials, and assessed the overall quality of evidence using the GRADE approach.

RESULTS

Seventeen randomized trials (n = 5043) were included in this network meta-analysis study. A network geometry was formed with 14 antimalarial treatment options such as artemether-lumefantrine (AL), artemisinin-piperaquine, artesunate-amodiaquine, artesunate-mefloquine (ASMQ), artesunate-chloroquine, artesunate-mefloquine home treatment, artesunate-mefloquine 2-day course, artesunate plus sulfadoxine-pyrimethamine, chloroquine, dihydroartemisinin-piperaquine (DHP), dihydroartemisinin-piperaquine home treatment, dihydroartemisinin-piperaquine 4-day course, dihydroartemisinin-piperaquine and added artesunate, sulfadoxine-pyrimethamine. A maximum number of trials included was DHP compared to ASMQ (n = 5). In general, DHP had better efficacy than AL at day 28 (DHP vs AL: OR 2.5, 95%CI:1.08-5.8). There is low certainty evidence due to limited number of studies and small trials.

DISCUSSION/ CONCLUSIONS

The findings suggest the superiority of DHP (3-day course) to AL and other comparator ACTs are with the overall low/very low quality of evidence judgements. Moreover, one drug regimen is better than another is only if current drug-resistance patterns are at play. For example, the AL might be better than DHP in areas where both artemisinin and piperaquine resistance patterns are prevalent. For substantiation, well-designed larger trials from endemic countries are needed. In the light of benefit versus harm concept, future analysis with safety information is recommended.

Morphology of Glycycometus malaysiensis, a domestic mite in Malaysia

Glycycometus malaysiensis is an allergenic domestic mite found in houses. G. malaysiensis is known to be highly similar to and is often mistaken as Blomia tropicalis, one of the major house dust mite species that causes asthma and allergic diseases in many tropical and subtropical regions. It was also suggested that these mites cross-react with each other and that the prevalence of G. malaysiensis might be higher than previous reports. A review on the taxonomic keys as well as light and scanning electron micrographs of G. malaysiensis are presented to appreciate the fine morphological structures of G. malaysiensis. The mouth, setae, legs (trochanter, femur, genu, tibia and tarsus) and the sexual organs (genital openings, genital setae and genital suckers) of G. malaysiensis are outlined. The morphology of G. malaysiensis is also compared with that of B. tropicalis to delineate the key features for the differentiation between these two mite species.

Parasites in soil samples from Signy island, Antarctica

Studies on parasite populations in Antarctic soils are scarce and thus little is known about the threat of these parasites towards either the natural fauna or human visitors. However, human presence in Antarctica, mainly through research and tourism, keeps increasing over time, potentially exposing visitors to zoonotic infections from Antarctic wildlife and environment. Most available literature to date has focused on faecal samples from Antarctic vertebrates. Therefore, this study addressed the possible presence of parasites in Antarctic soil that may be infectious to humans. Soil samples were obtained from five locations on Signy Island (South Orkney Islands, maritime Antarctic), namely North Point and Gourlay Peninsula (penguin rookeries), Pumphouse (relic coal-powered pump house), Jane Col (barren high altitude fellfield) and Berntsen Point (low altitude vegetated fellfield close to current research station). Approximately 10% of the soil samples (14/135) from 3 out of the 5 study sites had parasites which included Diphyllobotridae spp. eggs, Cryptosporidium sp., an apicomplexan protozoa (gregarine), Toxoplasma gondii, helminths (a cestode, Tetrabothrius sp., and a nematode larva) and mites. The presence of parasites in the 3 sites are most likely due to the presence of animal and human activities as two of these sites are penguin rookeries (North Point and Gourlay Peninsula) while the third site (Pumphouse Lake) has human activity. While some of the parasite species found in the soil samples appear to be distinctive, there were also parasites such as Cryptosporidium and Toxoplasma gondii that have a global distribution and are potentially pathogenic.

Identification and ultrastructural characterization of Acanthamoeba bacterial endocytobionts belonging to the Alphaproteobacteria class

The detection and identification of two endocytobiotic bacterial strains, one affiliated to the “Candidatus Caedibacter acanthamoebae”/“Ca. Paracaedimonas acanthamoeba”, and another to the endosymbiont of Acanthamoeba UWC8 and “Ca. Jidaibacter acanthamoeba” are described. For endocytobiont screening, we developed a PCR method with a set of broad-range bacterial 16S rRNA primers to substitute the commonly used but technically demanding fluorescent in situ hybridization technique. Our PCR test alone without sequencing failed to discriminate the endocytobiont-containing and endocytobiont-free Acanthamoeba sp. due to the presence of mismatched primers to host mitochondrial DNA. We highlighted the need to perform bacterial primer checking against the Acanthamoeba genome to avoid false positive detection in PCR. Although the genetic aspect of “Ca. Caedibacter acanthamoebae”/“Ca. Paracaedimonas acanthamoeba” and the endosymbiont of Acanthamoeba UWC8/“Ca. Jidaibacter acanthamoeba” are well studied, knowledge pertaining to their morphologies are quite vague. Hence, we used transmission electron microscopy to examine our endocytobionts which are affiliated to previously described intracellular bacteria of Acanthamoeba sp. We used good-quality TEM images for the localization and the fate of the current endocytobionts inside different life stages of the hosts. Furthermore, to the best of our knowledge, our TEM findings are the first to provide morphological evidence for the clearance of defective Acanthamoeba endocytobionts via an autophagic-like process.

Association of tumour necrosis factor-α (TNF-α) gene polymorphisms (-308 G>A and -238 G>A) and the risk of severe dengue: A meta-analysis and trial sequential analysis

Individual studies have assessed the association between TNF-α-308G>A and TNF-α-238 G>A polymorphisms and severity of dengue infection. However, the results are inconclusive and most studies had small sample sizes. The objective of this study was to summarize the evidence of association between TNF-α-308 G>A and TNF-α-238 G>A and severity of dengue infection. This study follows the preferred reporting items for systematic reviews and meta- analyses of genetic association studies, recommended by PLOS One. We calculated pooled odds ratio and its 95% confidence interval (CI) to estimate the association between TNF-α-308 G>A or TNF-α-238 G>A and the risk of severe dengue infections. To determine the information size required for this meta-analysis study, a trial sequential analysis (TSA) was done. Eight studies (640 cases and 1275 controls), which assessed the association of TNF-α-308 G>A or TNF-α-238 G>A and the risk of DHF were included. Overall, we found no significant association between TNF-α-308 G>A and the DHF risk in the allelic model (OR, 0.91; 95% CI, 0.51-1.63), the recessive model (OR,1.32;95%CI,0.73-2.37), the dominant model (OR,0.93;95%CI:0.59-1.47) or the additive model (OR,1.43,95;95%CI:0.79-2.59). There was also no significant association between TNF-α-238 G>A and DHF risk under the allele contrast model (OR:1.51;95%CI:0.88-2.58), the recessive model (OR,1.48,95% CI:0.33-6.58), the dominant model (OR,1.48;95%CI:0.56-3.92), or the additive model (OR:1.5;95%CI:0.34-6.69). On subgroup analysis, neither the Asian population nor the non-Asian population showed significant association between TNF-α-308 G>A/TNF-α-238 G>A and the DHF risk under any genetic models. Leave-one-out meta-analysis showed stability of the results. TSA plots suggested that the sample size in this meta-analysis study was below the required information size. The findings suggest an inclusive evidence of the association between TNF-α-308/ TNF-α-238 G>A and the risk of developing severe dengue infection. Large studies with evidence of Hardy-Weinberg equilibrium, assessing gene-gene interactions are recommended.

Kytococcus sedentarius and Micrococcus luteus: highly prevalent in indoor air and potentially deadly to the immunocompromised - should standards be set?

The multifarious types of infections contracted from indoor environments show that buildings can serve as a reservoir for infectious bacteria. This study is an investigation into the type and concentrations of bacteria in the indoor and outdoor environments of an electronic factory, an office and a winery in Malaysia. Trypticase soy agar (TSA) (with ambient air incubation) and TSA supplemented with haemin and NADH (with CO₂ enhanced incubation) were used for the isolation of bacteria. The plates were incubated at 37ºC for 3 days. A random selection of bacterial isolates were Gram stained and identified using the BD BBL Crystal Identification Systems. Kytococcus sedentarius and Micrococcus luteus were the predominant bacterial species identified from indoor air. These bacteria were present at relatively high concentrations in indoor air, at times, above 800 colony forming units per cubic meter (CFU/m³) of air. This indicates that both K. sedentarius and M. luteus can survive a wide range of adverse conditions, including chemical contamination and ultraviolet exposure. M. luteus is a known cause of pneumonia in immunocompromised individuals and has also been implicated in skin infections. Recent reports suggest species of kytococci as emerging opportunistic pathogens of the immunocompromised, paediatrics and the elderly. We postulate that opportunistic bacteria, such as the kytococci and the micrococci, may also have a potential role in instigating subclinical, more subtle symptoms of disease in inmmunocompetent individuals.

Detection of dengue viruses and Wolbachia in Aedes aegypti and Aedes albopictus larvae from four urban localities in Kuala Lumpur, Malaysia

Dengue fever (DF) is currently one of the most important mosquito-borne diseases that affects humans. Dengue fever (DF) and dengue hemorrhagic fever (DHF) are caused by four serotypes of dengue viruses (DENV-1 to DENV-4). The main vector transmitting dengue is Aedes aegypti while Aedes albopictus acts as a secondary vector. As treatment is unavailable and the first dengue vaccine approved in Mexico, Dengvaxia® has yet to be accepted worldwide, prevention of the disease relies heavily on surveillance and control of mosquito vectors. A transgene driver, Wolbachia was found to limit the transmission of dengue virus in Aedes mosquitoes. Wolbachia alone was able to inhibit viral replication, dissemination and transmission in A. aeygpti mosquitoes in experimental studies. In A. albopictus, Wolbachia did not affect the replication of dengue virus but was able to reduce the viral infection of mosquito salivary glands and limit transmission. Studies on Wolbachia have all been carried out in adult Aedes mosquitoes, hence this study was conducted to determine the presence of dengue virus serotypes and Wolbachia in A. aegypti and A. albopictus larvae collected from ovitraps in four localities in Kuala Lumpur viz. Happy Gardens, IMU Bukit Jalil, Ampang and Taman Yarl. Another objective of this study was to determine the association between dengue virus serotypes and the presence of Wolbachia in A. aegypti and A. albopictus larvae. A total of 300 mosquito larvae was collected; 99 (Happy Gardens), 85 (Bukit Jalil), 73 (Ampang) and 43 (Taman Yarl). Out of 300 larvae collected, 284 were identified as A. albopictus and 16 others were identified as A. aegypti. Of the 284 A. albopictus larvae collected, 211 (74.3%) and 73 (25.7%) were found to be negative and positive for dengue virus respectively. The dengue serotypes detected were 2 DENV-2 (2.7%), 58 DENV-3 (79.5%) and 13 DENV-4 (17.8%). DENV-1 was not detected in any of the A. albopictus larvae. For A. aegypti, out of 16 A. aegypti larvae collected, 12 (75%) were found to be negative and 4 (25%) were positive for DENV-2. For the detection of Wolbachia in A. albopictus, 71 out of 284 (25%) and 213 (75%) larvae were found to be positive and negative for Wolbachia respectively. For A. aegypti, 4 (25%) and 12 (75%) out of 16 larvae were positive and negative for Wolbachia respectively. This is the first report of Wolbachia in A. albopictus and A. aegypti larvae in Malaysia. A chisquare test analysis to determine the association between dengue virus and Wolbachia in A. albopictus and A. aegypti larvae collected from the four localities in Kuala Lumpur showed that there was no association (χ² = 3.080; df = 1; P > 0.05).

The correlation of Acanthamoeba from the ventilation system with other environmental parameters in commercial buildings as possible indicator for indoor air quality

The free-living protozoan Acanthamoeba is an opportunistic pathogen that is ubiquitous in our environment. However, its role in affecting indoor air quality and ill-health of indoor occupants is relatively unknown. The present study investigated the presence of Acanthamoeba from the ventilation system and its correlation with other indoor air quality parameters, used in the industry code of practice and its potential as an indicator for indoor air quality. Indoor air quality assessments were carried out in nine commercial buildings with approval from the building management, and the parameters assessed were as recommended by the Department of Occupational Safety and Health. The presence of Acanthamoeba was determined through dust swabs from the ventilation system and indoor furniture. Logistic regression was performed to study the correlation between assessed parameters and occupants’ complaints. A total of 107 sampling points were assessed and 40.2% of the supplying air diffuser and blowing fan and 15% of the furniture were positive for cysts. There was a significant correlation between Acanthamoeba detected from the ventilation system with ambient total fungus count (r=0.327; p=0.01) and respirable particulates (r=0.276; p=0.01). Occupants’ sick building syndrome experience also correlated with the presence of Acanthamoeba in the ventilation system (r=0.361; p=0.01) and those detected on the furniture (r=0.290; p=0.01). Logistic regression showed that there was a five-fold probability of sick building syndrome among occupants when Acanthamoeba was detected in the ventilation system.

Salivary glucose in monitoring glycaemia in patients with type 1 diabetes mellitus: a systematic review

Background

Incidence of type 1 diabetes mellitus is increasing worldwide. Monitoring glycaemia is essential for control of diabetes mellitus. Conventional blood-based measurement of glucose requires venepuncture or needle prick, which is not free from pain and risk of infection. The non-invasiveness, ease and low-cost in collection made saliva an attractive alternative sample. The objective of this review was to systematically review the evidence on the relationship between salivary glucose level and blood glucose level in monitoring glycaemia in patients with type 1 diabetes mellitus.

Methods

We searched studies which evaluate salivary glucose levels and serum glycaemia in type 1 diabetes mellitus in electronic databases of MEDLINE, EMBASE, Ovid and Google Scholar. We selected the eligible studies, following the inclusion criteria set for this review. Due to heterogeneity of studies, we conducted qualitative synthesis of studies.

Results

Ten observational studies were included in this review, including a total of 321 cases and 323 controls with ages between 3 and 61 years and the majority were males (62%). Two studies were done exclusively on children below 17 years old. The significant difference between salivary glucose levels in type 1 diabetes mellitus and controls were reported in 6 studies with 8 data sets. Five studies with 7 datasets reported the correlation coefficient between salivary glucose and blood glucose in patients with diabetes.

Conclusions

Findings suggest that salivary glucose concentrations may be helpful in monitoring glycaemia in type 1 diabetes mellitus. However, the utility of using salivary glucose level to monitor glycaemia should be evaluated in future well designed, prospective studies with adequate number of participants with type 1 diabetes mellitus.

Electronic supplementary material

The online version of this article (doi:10.1186/s40200-017-0287-5) contains supplementary material, which is available to authorized users.

Association between telomere length and the risk of colorectal cancer: a meta-analysis of observational studies

BACKGROUND

Human chromosomes are capped and stabilized by telomeres. Telomere length regulates a 'cellular mitotic clock' that defines the number of cell divisions and hence, cellular life span. This study aimed to synthesize the evidence on the association between peripheral blood leucocytes (PBL) telomere length and the risk of colorectal cancer (CRC).

METHODS

We searched relevant studies in electronic databases. When two or more observational studies reported the same outcome measures, we performed pooled analysis. All the analyses were performed on PBL using PCR. The odds ratio (OR) and its 95% confidence interval (CI) were used to assess the strength of association.

RESULTS

Seven studies (with 8 datasets) were included in this meta-analysis; 3 prospective studies, 3 retrospective studies and 1 study with a separate prospective and retrospective designs. The pooled analysis of 4 prospective studies (summary OR 1.01, 95% CI: 0.77-1.34, I ²:30%) and 4 retrospective studies (summary OR 1.65, 95% CI: 0.96-2.83, I ²:96%) showed no relationship between PBL telomere length and the CRC risk. A subgroup analysis of 2 prospective studies exclusively on females also showed no association between PBL telomere length and the CRC risk (summary OR, 1.17, 95% CI:0.72-1.91, I ²:57%).

CONCLUSION

The current analysis is insufficient to provide evidence on the relationship between PBL telomere length and the risk of CRC. Findings suggest that there may be a complex relationship between PBL telomere length and the CRC risk or discrepancy between genetics, age of patients and clinical studies. Future well powered, large prospective studies on the relationship between telomere length and the risk of CRC, and the investigations of the biologic mechanisms are recommended.

Sero-prevalence study of IgE responses to allergens from Malaysian house dust (HDM) and storage mites (SM)

Allergens of Dermatophagoides and Blomia species are well-characterized but not for other species. This study was conducted to determine the prevalence of allergic sensitization to house dust (HDM) and storage mites (SM). One hundred adult subjects (aged ≥ 18) were recruited. The mite specific IgE of all allergic subjects were higher compared with healthy subjetcs despite being not statistically significant except for D. farinae and G. malaysiensis. The mean serum IgE levels against HDM and SM for allergic subjects were significantly higher compared with those in healthy subjects. They were mainly sensitized to Dermatophagoides farinae (35%) and Glycycometus malaysiensis (37%). Immunoblots revealed not all allergic subjects showed positive immuno-reactivity against the mites tested. Single or multiple bands were observed for different species. The subjects were commonly sensitized to Group 2 (9-12 kDa), 10 (38 kDa) and 18 (40-48 kDa) allergens. Twenty-one out of 60 allergic subjects were sensitized to either one or more species. The majority of them (71%) were sensitized to single species. The allergic subjects were mainly sensitized to D. pteronyssinus, followed by Tyrophagus putrecentiae and Aleuroglyphus ovatus. Seven were solely sensitized to HDM while 10 were solely sensitized to SM. Four subjects were sensitized to both. Pre-adsorption study revealed no cross-reactivity. There was difference between the prevalence and reactivity to allergens of HDM and SM in these subjects. Both ELISA and immunoblot did not correlate well but can complement each other in improving the detection of mite allergens to the species level.

Isolation and identification of mites associated with raw and commercial farm edible bird nests

The global demand for edible bird nests (EBNs) is high, especially from Hong Kong and Peoples Republic of China. Recently, this industry was greatly affected when China banned the import of all the EBNs from Malaysia (except for canned version) due to detection of high levels of nitrites. Several cases of anaphylaxis following ingestion of EBNs were reported. The source(s) of these allergens remain unknown. Mites have been reported to trigger allergic responses. Hence, this study was designed to quantify, isolate and identify the mites that are associated with EBNs. The raw EBNs were purchased from swiftlet farms in five locations in Peninsular Malaysia while the commercial nests were purchased from five different Chinese traditional medicinal shops. The average mite density of all the raw nests was 285 ± 603 mites per gram of EBN while the commercial nests had a much lower mean value of 21 ± 32 mites per gram of EBN (p = 0.082). Among the raw EBNs, the nests from Kajang had the highest average mite density (946 ± 1443 mites/g of EBN) whereas the nests from Kuala Sanglang had the lowest (54 ± 34 mites/g of EBN). Among the commercial EBNs, the nests from Company D had the highest average mite density (76 ± 18 mites/g of EBN) whereas the nests from Company A were free of mites. Overall, the average densities of mites in the raw nests obtained from southern regions of Malaysia (Selangor and Johor) were higher than those nests obtained from the northern regions (Kedah and Kelantan). Thirty types of mites were isolated from both the raw and commercial nests. Among these, some are probably feather mites (Eustathia cultrifer, Pteroherpus garrulacis, Pterodectes amaurochalinus, Laminalloptes sp., Berlesella alata and Neochauliacia sp.), house dust and storage mites (Suidasia sp., Austroglycyphagus sp., and Aleuroglyphus ovatus), mesostigmatid mites (Dermanyssus sp.), prostigmatid mites (Cheyletus sp., tarsonemid and cunaxid mites), astigmatid mites (Collocalidectes sp., Streetacarus sp. and Hemisarcoptes sp.) and oribatid mites. This study provides baseline information on the density and type of mites that are probably associated with EBNs. This study also heightens the importance of mites as a possible source of EBN-associated anaphylaxis.

Culture and molecular identification of fungal contaminants in edible bird nests

Widespread food poisoning due to microbial contamination has been a major concern for the food industry, consumers and governing authorities. This study is designed to determine the levels of fungal contamination in edible bird nests (EBNs) using culture and molecular techniques. Raw EBNs were collected from five house farms, and commercial EBNs were purchased from five Chinese traditional medicine shops (companies A-E) in Peninsular Malaysia. The fungal contents in the raw and commercial EBNs, and boiled and unboiled EBNs were determined. Culturable fungi were isolated and identified. In this study, the use of these methods revealed that all EBNs had fungal colony-forming units (CFUs) that exceeded the limit set by Standards and Industrial Research Institute of Malaysia (SIRIM) for yeast and moulds in EBNs. There was a significant difference (p < 0.05) in the number of types of fungi isolated from raw and commercial EBNs, but no significant difference in the reduction of the number of types of fungi after boiling the EBNs (p > 0.05). The types of fungi isolated from the unboiled raw EBNs were mainly soil, plant and environmental fungi, while the types of fungi isolated from the boiled raw EBNs, unboiled and boiled commercial EBNs were mainly environmental fungi. Aspergillus sp., Candida sp., Cladosporium sp., Neurospora sp. and Penicillum sp. were the most common fungi isolated from the unboiled and boiled raw and commercial EBNs. Some of these fungi are mycotoxin producers and cause opportunistic infections in humans. Further studies to determine the mycotoxin levels and methods to prevent or remove these contaminations from EBNs for safe consumption are necessary. The establishment and implementation of stringent regulations for the standards of EBNs should be regularly updated and monitored to improve the quality of the EBNs and consumer safety.

A systematic review of the efficacy of a single dose artemisinin-naphthoquine in treating uncomplicated malaria

Background

This study aimed to synthesize the existing evidence on the efficacy and safety of a single dose artemisinin–naphthoquine (ASNQ) for treatment of uncomplicated malaria in endemic countries.

Methods

A meta-analysis of randomized, controlled trials (RCT), assessing efficacy and safety of single dose ASNQ was carried out. Comparator drugs included artemether–lumefentrine (AL), chloroquine plus sulfadoxine-pyrimethamine (CQSP) and dihydroartemisinin–piperaquine (DHP). The efficacy and safety profile of non-comparator, single-arm studies on the single dose ASNQ was also assessed. The primary endpoint was efficacy defined as an absence of PCR-confirmed parasitaemia. The methodological quality of the included studies was assessed using the six domains for the risk of bias.

Results

Five RCTs and three single-arm studies were included in this review. As RCT studies did not compare the same anti-malarial drugs, it was difficult to do a pooled analysis. At day 28, a pooled analysis of two RCTs (n = 271) showed a comparable efficacy on PCR-confirmed parasitaemia between ASNQ and AL. Another RCT, which compared ASNQ and CQSP or ASNQ and DHP, also showed comparable efficacy. At day 42, one RCT comparing ASNQ and DHP and another RCT comparing ASNQ and AL reported comparable levels of efficacy. The proportion of parasite clearance was faster in the ASNQ groups than the comparators at day 1, and almost all parasites were cleared by day 3 in the ASNQ groups.

Conclusions

The present review provides some evidence to support that there is similar efficacy and safety of the single dose ASNQ compared to other anti-malarial drugs in treating uncomplicated malaria. Larger, adequately powered, well-designed studies are recommended to substantiate the efficacy and safety in different populations and in different epidemiological settings. As the potential evolution of drug resistance is a great concern and this cannot be addressed in a short-term study, the use of single dose ASNQ needs further evaluation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-015-0919-5) contains supplementary material, which is available to authorized users.

Field evaluation of a rapid diagnostic test to detect antibodies in human toxocariasis

Human toxocariasis which is caused mainly by the larvae of Toxocara canis and Toxocara cati, is a worldwide zoonotic disease that can be a potentially serious human infection. The enzyme-linked immunosorbent assay (ELISA) using T. canis excretory-secretory (TES) antigens harvested from T. canis larvae is currently the serological test for confirming toxocariasis. An alternative to producing large amounts of Toxocara TES and improved diagnosis for toxocariasis is through the development of highly specific recombinant antigens such as the T. canis second stage larva excretory-secretory 30 kDa protein (recTES-30). The aim of this study was to evaluate the sensitivity and specificity of a rapid diagnostic kit (RDT, named as iToxocara kit) in comparison to recTES-30 ELISA in Serendah Orang Asli village in Selangor, Malaysia. A total of 133 subjects were included in the study. The overall prevalence rates by ELISA and RDT were 29.3% and 33.1%, respectively, with more positive cases detected in males than females. However, no association was found between toxocariasis and gender or age. The percentage sensitivity, specificity, positive predictive value and negative predictive value of RDT were 85.7%, 90.1%, 80% and 93.2%, respectively. The prevalence for toxocariasis in this population using both ELISA and RDT was 27.1% (36/133) and the K-concordance test suggested good agreement of the two tests with a Cohen's kappa of 0.722, P<0.01. In addition, the followed-up Spearman rank correlation showed a moderately high correlation at R=0.704 and P<0.01. In conclusion, the RDT kit was faster and easier to use than an ELISA and is useful for the laboratory diagnosis of hospitalized cases of toxocariasis.

A Systematic Review and Meta-Analysis of Medical Students' Perspectives on the Engagement in Research

Engaging students in active learning lies at the center of effective higher education. In medical schools, students' engagement in learning and research has come under increasing attention. The objective of this study was to synthesize evidence on medical students' perspectives on the engagement in research. We performed a systematic review and meta-analysis. Relevant studies were searched in electronic databases. The methodological quality of the included studies was assessed. Overall, 14 observational studies (with 17 data sets) were included. In general, many studies did not use the same questionnaires and the outcome measurements were not consistently reported; these presented some difficulties in pooling the results. Whenever data permitted, we performed pooled analysis for the 4 education outcomes. A Bayesian meta-analytical approach was supplemented as a measure of uncertainty. A pooled analysis showed that 74% (95% confidence interval [CI]: 1.57%-11.07%; I2: 95.2%) of those students who engaged in research (while at the medical school) had positive attitudes toward their research experiences, whereas 49.5% (95% CI: 36.4%-62.7%; I2: 93.4%) had positive attitudes toward the study of medical sciences, 62.3% (95% CI: 46.7%-77.9%; I2: 96.3%) had self-reported changes in their practices, and 64% (95% CI: 30.8%-96.6%; I2: 98.5%) could have published their work. There was substantial heterogeneity among studies. We acknowledged the caveats and the merit of the current review. Findings showed that engagement in research resulted in favorable reactions toward research and academic learning. Future well-designed studies using standardized research tools on how to engage students in research are recommended.

Malaria and soil-transmitted intestinal helminth co-infection and its effect on anemia: a meta-analysis

This study aimed to synthesize available evidence on the extent of malaria and soil-transmitted intestinal helminth (STH) co-infections in people living in endemic countries and to explore the effect of interactions between malaria and STHs on anemia. We searched relevant studies in electronic databases up to March 2013. Studies comparing malaria and STH co-infected patients with those not co-infected were included and the effect estimates were pooled using a random-effects model. We identified 30 studies for meta-analyses of which 17 were cross-sectional design. The majority of included studies (80%) were carried out in African countries. Among pregnant women, those infected with hookworm were found to have higher association with malaria infection compared with those without (summary OR: 1.36; 95% CI: 1.17-1.59; I(2): 0%). Among non-pregnant adults, the summary OR of the association between anemia and the combined malaria and STH was 2.91 (1.38-6.14). The summary OR of the association between anemia and malaria alone was 1.53 (0.97-2.42), while the association between anemia and STH alone was 0.28 (0.04-1.95). There is no good evidence to support a different effect of malaria and STH on anemia. A subgroup analysis showed a higher risk of malaria infection in the primigravidae (summary OR: 1.61; 95% CI: 1.3-1.99; I(2): 0%). In conclusion, the malaria-STH co-infection was variable with complex outcomes on anemia.

In vitro effect of important herbal active constituents on human cytochrome P450 1A2 (CYP1A2) activity

This study was designed to investigate eight herbal active constituents (andrographolide, asiaticoside, asiatic acid, madecassic acid, eupatorin, sinensetin, caffeic acid, and rosmarinic acid) on their potential inhibitory effects on human cytochrome P450 1A2 (CYP1A2) activity. A fluorescence-based enzyme assay was performed by co-incubating human cDNA-expressed CYP1A2 with its selective probe substrate, 3-cyano-7-ethoxycoumarin (CEC), in the absence or presence of various concentrations of herbal active constituents. The metabolite (cyano-hydroxycoumarin) formed was subsequently measured in order to obtain IC50 values. The results indicated that only eupatorin and sinensetin moderately inhibited CYP1A2 with IC50 values of 50.8 and 40.2 μM, while the other active compounds did not significantly affect CYP1A2 activity with IC50 values more than 100 μM. Ki values further determined for eupatorin and sinensetin were 46.4 and 35.2 μM, respectively. Our data indicated that most of the investigated herbal constituents have negligible CYP1A2 inhibitory effect. In vivo studies however may be warranted to ascertain the inhibitory effect of eupatorin and sinensetin on CYP1A2 activity in clinical situations.

Is Plasmodium vivax malaria a severe malaria?: a systematic review and meta-analysis

Background

Plasmodium vivax is one of the major species of malaria infecting humans. Although emphasis on P. falciparum is appropriate, the burden of vivax malaria should be given due attention. This study aimed to synthesize the evidence on severe malaria in P. vivax infection compared with that in P. falciparum infection.

Methods/Principal Findings

We searched relevant studies in electronic databases. The main outcomes required for inclusion in the review were mortality, severe malaria (SM) and severe anaemia (SA). The methodological quality of the included studies was assessed using the Newcastle-Ottawa Scale. Overall, 26 studies were included. The main meta-analysis was restricted to the high quality studies. Eight studies (n = 27490) compared the incidence of SM between P. vivax infection and P. falciparum mono-infection; a comparable incidence was found in infants (OR: 0.45, 95% CI:0.04–5.68, I²:98%), under 5 year age group (OR: 2.06, 95% CI: 0.83–5.1, I²:83%), the 5–15 year-age group (OR: 0.6, 95% CI: 0.31–1.16, I²:81%) and adults (OR: 0.83, 95% CI: 0.67–1.03, I²:25%). Six studies reported the incidences of SA in P. vivax infection and P. falciparum mono-infection; a comparable incidence of SA was found among infants (OR: 3.47, 95%:0.64–18.94, I²: 92%), the 5–15 year-age group (OR:0.71, 95% CI: 0.06–8.57, I²:82%). This was significantly lower in adults (OR:0.75, 95% CI: 0.62–0.92, I²:0%). Five studies (n = 71079) compared the mortality rate between vivax malaria and falciparum malaria. A lower rate of mortality was found in infants with vivax malaria (OR:0.61, 95% CI:0.5–0.76, I²:0%), while this was comparable in the 5–15 year- age group (OR: 0.43, 95% CI:0.06–2.91, I²:84%) and the children of unspecified-age group (OR: 0.77, 95% CI:0.59–1.01, I²:0%).

Conclusion

Overall, the present analysis identified that the incidence of SM in patients infected with P. vivax was considerable, indicating that P. vivax is a major cause of SM. Awareness of the clinical manifestations of vivax malaria should prompt early detection. Subsequent treatment and monitoring of complications can be life-saving.

Until recently, vivax malaria has received less attention than falciparum malaria and was deemed neglected. There has been a surge in studies that documented the contribution of Plasmodium vivax to severe malaria in some endemic countries such as Thailand, Brazil, Indonesia, Papua New Guinea and India. We aimed to synthesize the evidence on severe malaria in P. vivax infection compared with that in P. falciparum infection. We searched relevant studies in electronic databases. The combined results of the eight relatively high quality studies showed a comparable incidence between vivax malaria and falciparum malaria in infants, under 5 year age group, the 5–15 year age group and adults. The combined results of the six relatively high quality studies revealed a comparable incidence of severe anaemia between P. vivax infection and P. falciparum mono-infection in both the infants and the 5–15 year age group. Considering that severe malaria and deaths attributable to P. vivax is not a rare event, raised clinical awareness of the manifestations of vivax malaria in patients of any age should prompt early detection of malaria. It is likely that early detection, appropriate treatment commenced in a timely manner and close monitoring of any complications could be life-saving and contribute to the attainment of the global vision of no malaria deaths.

Structural analysis of raw and commercial farm edible bird nests

Edible bird nests (EBNs) are consumed worldwide for various health benefits. EBNs are nests built from the saliva of swiftlets of Aerodramus species. The global market for EBNs is on the rise, especially from Hong Kong and mainland China. In the past, EBNs were harvested mainly from natural caves; however in the recent years, there has been a rapid growth of swiftlet farming. Little is known about the actual composition of EBNs except for protein, carbohydrate, ash and lipid contents, amino acids, vitamins and macro/ micronutrients. Besides the biochemical components of EBNs, are there any other structures that are associated with EBNs? This paper reports on the structural analysis of raw unprocessed farm and processed commercial EBNs. The raw EBNs were purchased from swiftlet farms in five locations in Peninsula Malaysia: Kuala Sanglang (Perlis; 6° 16' 0"N, 100° 12' 0"E), Pantai Remis (Perak; 4º 27' 0" N, 100º 38' 0" E), Kluang (Johor; 02º 012 303N 103º 192 583E), Kajang (Selangor; 2º 59' 0"N, 101º 47' 0"E) and Kota Bharu (Kelantan; 6º 8' 0"N, 102º 15' 0"E). The commercial nests were purchased from five different Chinese traditional medicinal shops (Companies A-E). A portion of each EBN was randomly broken into small fragments, attached to carbon tape and coated with gold and palladium particles for examination and photography under a scanning electron microscope. Structural analysis revealed the presence of mites, fungi, bacteria and feather strands on both the raw and commercial nests. Mite eggshells and faecal pellets, and body parts of other arthropods were seen only in the raw nests. The commercial nests had a variety of unidentified structures and substances coated on the nests' surfaces that were not found on the raw nests. The presence of these contaminants may jeopardise the quality of EBNs and pose health risks to consumers. Further identification of the mites and their allergens, fungi and bacteria are on-going and will be reported separately.

Efficacy and safety of dihydroartemisinin-piperaquine for treatment of Plasmodium vivax malaria in endemic countries: meta-analysis of randomized controlled studies

BACKGROUND

This study aimed to synthesize available evidence on the efficacy of dihydroartemisinin-piperaquine (DHP) in treating uncomplicated Plasmodium vivax malaria in people living in endemic countries.

METHODOLOGY AND PRINCIPAL FINDINGS

This is a meta-analysis of randomized controlled trials (RCT). We searched relevant studies in electronic databases up to May 2013. RCTs comparing efficacy of (DHP) with other artemisinin-based combination therapy (ACT), non-ACT or placebo were selected. The primary endpoint was efficacy expressed as PCR-corrected parasitological failure. Efficacy was pooled by hazard ratio (HR) and 95% CI, if studies reported time-to-event outcomes by the Kaplan-Meier method or data available for calculation of HR Nine RCTs with 14 datasets were included in the quantitative analysis. Overall, most of the studies were of high quality. Only a few studies compared with the same antimalarial drugs and reported the outcomes of the same follow-up duration, which created some difficulties in pooling of outcome data. We found the superiority of DHP over chloroquine (CQ) (at day > 42-63, HR:2.33, 95% CI:1.86-2.93, I (2): 0%) or artemether-lumefentrine (AL) (at day 42, HR:2.07, 95% CI:1.38-3.09, I (2): 39%). On the basis of GRADE criteria, further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate.

DISCUSSION/CONCLUSION

Findings document that DHP is more efficacious than CQ and AL in treating uncomplicated P. vivax malaria. The better safety profile of DHP and the once-daily dosage improves adherence, and its fixed co-formulation ensures that both drugs (dihydroartemisinin and piperaquine) are taken together. However, DHP is not active against the hypnozoite stage of P. vivax. DHP has the potential to become an alternative antimalarial drug for the treatment uncomplicated P. vivax malaria. This should be substantiated by future RCTs with other ACTs. Additional work is required to establish how best to combine this treatment with appropriate antirelapse therapy (primaquine or other drugs under development).

Diabetes and infections-hepatitis C: is there type 2 diabetes excess in hepatitis C infection?

Individual epidemiologic studies as well as the pooled analysis of observational studies have indicated the association between type 2 diabetes (T2D) and hepatitis C virus infection (HCV). Whether HCV infection is the cause of diabetes or diabetic patients are more prone to get HCV infection is still in question. The objective of the present review was to provide answers to this issue, based on available evidence from epidemiologic, molecular, experimental and therapeutic studies. Our current understanding of how chronic HCV infection could induce T2D is incomplete, but it seems twofold based on both direct and indirect roles of the virus. HCV may directly induce insulin resistance (IR) through its proteins. HCV core protein was shown to stimulate suppressor of cytokine signaling, resulting in ubiquitination and degradation of tyrosine kinase phosphorylated insulin receptor substrates (IRS1/2) in proteasomes. HCV-nonstructural protein could increase protein phosphatase 2A which has been shown to inactivate the key enzyme Akt by dephosphorylating it. Insulin signaling defects in hepatic IRS-1 tyrosine phosphorylation and PI3-kinase association/activation may contribute to IR, which leads to the development of T2D in patients with HCV infection. The peroxisome proliferator-activated receptors (PPARs) are also implicated. PPARα/γ, together with their obligate partner RXR, are the main nuclear receptors expressed in the liver. PPARα upregulates glycerol-3-phosphate dehydrogenase, glycerol kinase, and glycerol transport proteins, which allows for glucose synthesis during fasting states. Decreased activity of PPARs could attribute to HCV-induced IR. Immune-mediated mechanisms may be involved in the indirect role of HCV in inducing IR. It is speculated that TNF-alpha plays a major role in the pathogenesis of IR through lowering IRS1/2. Furthermore, HCV infection- triggered ER stress could lead to the activation of PP2A, which inhibits both Akt and the AMP-activated kinase, the regulators of gluconeogenesis. In summary, we illustrate that HCV infection is accompanied by multiple defects in the upstream insulin signaling pathway in the liver that may contribute to the observed prevalence of IR and diabetes. Future studies are needed to resolve this issue.

In vitro approaches to investigate cytochrome P450 activities: update on current status and their applicability

INTRODUCTION

Cytochromes P450 (CYPs) play a central role in the Phase I metabolism of drugs and other xenobiotics. It is estimated that CYPs can metabolize up to two-thirds of drugs present in humans. Over the past two decades, there have been numerous advances in in vitro methodologies to characterize drug metabolism and interaction involving CYPs.

AREAS COVERED

This review focuses on the use of in vitro methodologies to examine CYPs' role in drug metabolism and interaction. There is an emphasis on their current development, applicability, advantages and limitations as well as the use of in silico approaches in complementing and supporting in vitro data. The article also highlights the challenges in extrapolating in vitro data to in vivo situations.

EXPERT OPINION

Advances in in vitro methodologies have been made such that data can be used for in vivo prediction with comfortable degree of confidence. Improved assay designs and analytical techniques have permitted development of miniaturized assay format and automated system with improved sensitivity and throughput capacity. High-quality experimental designs and scientifically rigorous assessment/validation protocols remain crucial in developing reliable and robust in vitro models. With continued progress made in the field, in vitro methodologies will continually be employed in evaluating CYP activities in pharmaceutical industries and laboratories.

Acanthamoeba genotype T4 detected in naturally-infected feline corneas found to be in homology with those causing human keratitis

A total of 10 out of 65 cornea swab samples from cats with eye symptoms showed Acanthamoeba-like morphology after cultivation. By PCR and DNA sequencing of Acanthamoeba diagnostic fragment 3 (DF3), all 10 isolates from the positive samples were categorized into two homologous groups of AfC1 (PM1, PM2, PM3, PF6, KM7, KF8, KMK9) and AfC2 (PM4, PM5, KFK10) due to the presence of bases A(354) and G(354), respectively. Furthermore, DF3 of AfC1 and AfC2 showed 100% similarity with Genbank reference isolates with the accession numbers DQ087314, EU146073 and U07401, GU808323, which were Acanthamoeba castellanii strains genotype T4 originating from human keratitis. This finding suggests that A. castellani strains have the capability to infect cats and human under favorable conditions.

Prevalence, predictors and clinical significance of Blastocystis sp. in Sebha, Libya

BACKGROUND

Blastocystis sp. has a worldwide distribution and is often the most common human intestinal protozoan reported in children and adults in developing countries. The clinical relevance of Blastocystis sp. remains controversial. This study was undertaken to determine the prevalence of Blastocystis infection and its association with gastrointestinal symptoms among outpatients in Sebha city, Libya.

METHODS

A total of 380 stool samples were collected from outpatients attending the Central Laboratory in Sebha, Libya for routine stool examination. The presence of Blastocystis sp. was screened comparing light microscopy of direct smears against in vitro cultivation. Demographic and socioeconomic information were collected with a standardized questionnaire.

RESULTS

The overall prevalence of Blastocystis infection was 22.1%. The prevalence was significantly higher among patients aged ≥18 years compared to those aged < 18 years (29.4% vs 9.9%; x² = 19.746; P < 0.001), and in males compared to females (26.4% vs 17.5%; x² = 4.374; P = 0.036). Univariate analysis showed significant associations between Blastocystis infection and the occupational status (P = 0.017), family size (P = 0.023) and educational level (P = 0.042) of the participants. Multiple logistic regression analysis confirmed that the age of ≥ 18 years (OR = 5.7; 95% CI = 2.21; 9.86) and occupational status (OR = 2.2; 95% CI = 1.02, 4.70) as significant predictors of Blastocystis infection among this population. In those who had only Blastocystis infection but no other gastrointestinal parasitic infections, the prevalence of gastrointestinal symptoms was higher compared to those without Blastocystis infection (35.3% vs 13.2%; x² = 25.8; P < 0.001). The most common symptoms among these patients were abdominal pain (76.4%), flatulence (41.1%) and diarrhoea (21.5%).

CONCLUSIONS

Blastocystis sp. is prevalent and associated with gastrointestinal symptoms among communities in Sebha city, Libya. Age and occupational status were the significant predictors of infection. However, more studies from different areas in Libya are needed in order to delineate the epidemiology and clinical significance of this infection.

Heterologous expression of human cytochrome P450 (CYP) 2C19 in Escherichia coli and establishment of RP-HPLC method to serve as activity marker

In this study, a simple and reliable reverse-phase high-performance liquid chromatography (RP-HPLC) method was established and validated to analyze S-mephenytoin 4-hydroxylase activity of a recombinant CYP2C19 system. This system was obtained by co-expressing CYP2C19 and NADPH-CYP oxidoreductase (OxR) proteins in Escherichia coli (E. coli) cells. In addition to RP-HPLC, the expressed proteins were evaluated by immunoblotting and reduced CO difference spectral scanning. The RP-HPLC assay showed good linearity (r(2) = 1.00) with 4-hydroxymephenytoin concentration from 0.100 to 50.0 μm and the limit of detection was 5.00 × 10(-2) μm. Intraday and interday precisions determined were from 1.90 to 8.19% and from 2.20 to 14.9%, respectively. Recovery and accuracy of the assay were from 83.5 to 85.8% and from 95.0 to 105%. Enzyme kinetic parameters (Km , Vmax and Ki ) were comparable to reported values. The presence of CYP2C19 in bacterial membranes was confirmed by immunoblotting and the characteristic absorbance peak at 450 nm was determined in the reduced CO difference spectral assay. Moreover, the activity level of co-expressed OxR was found to be comparable to that of the literature. As a conclusion, the procedures described here have generated catalytically active CYP2C19 and the RP-HPLC assay developed is able to serve as CYP2C19 activity marker for pharmacokinetic drug interaction study in vitro.

Efficacy and safety of dihydroartemisinin-piperaquine for treatment of uncomplicated Plasmodium falciparum malaria in endemic countries: meta-analysis of randomised controlled studies

The present review aimed to synthesise available evidence on the efficacy of dihydroartemisinin-piperaquine (DP) in treating uncomplicated Plasmodium falciparum malaria in people living in malaria-endemic countries by performing a meta-analysis of relevant studies. We searched relevant studies in electronic data bases up to December 2011. Published results from randomised controlled trials (RCTs) comparing efficacy of DP with other artemisinin-based combination therapies (ACTs), or non-ACTs, or placebo were selected. The primary endpoint was 28-day and 42-day treatment failure. We identified 26 RCTs. Many of the studies included in the present review were of high quality. Overall, DP, artesunate-mefloquine (MAS3) and artemether-lumefentrine (AL) were equally effective for reducing the risk of recurrent parasitaemia. The PCR confirmed efficacy of DP (99.5%) and MAS3 (97.7%) at day 28 exceeded 90%; both are efficacious. Comparable efficacy was also found for DP (95.6%) and AL (94.3%). The present review has documented that DP is comparable to other currently used ACTs such as MAS3 and AL in treating uncomplicated falciparum malaria. The better safety profile of DP and once-daily dosage improves adherence and its fixed co-formulation ensures that both drugs are taken together. Our conclusion is that DP has the potential to become a first-line antimalarial drug.

Meta-analysis: the association between HIV infection and extrapulmonary tuberculosis

BACKGROUND

Extrapulmonary tuberculosis has been an AIDS-defining condition. Individual studies that highlight the association between HIV and extrapulmonary TB are available. Our objectives were to synthesis evidence on the association between extrapulmonary tuberculosis and HIV and to explore the effective preventive measures of these two diseases.

METHODS

This is a meta-analysis of observational studies reporting effect estimates on how HIV is associated with extrapulmonary tuberculosis. We searched for the eligible studies in the electronic databases using search terms related to HIV and extrapulmonary tuberculosis. Where possible, we estimated the summary odds ratios using random effects meta-analysis. We stratified analysis by the type of study design. We assessed heterogeneity of effect estimates within each group of studies was assessed using I (2) test.

RESULTS

Nineteen studies (7 case control studies and 12 cohort studies) were identified for the present study. The pooled analysis shows a significant association between HIV and extrapulmonary tuberculosis (summary odds ratio: 1.3; 95 % confidence interval (CI) 1.05-1.6; I (2): 0 %). In a subgroup analysis with two studies, a significant association was found between CD4+ count less than 100 and the incidence of extrapulmonary tuberculosis (summary OR: 1.31; 95 % CI 1.02-1.68; I (2): 0 %).

CONCLUSIONS

Findings show evidence on the association between extrapulmonary tuberculosis and HIV, based on case control studies. Further studies to understand the mechanisms of interaction of the two pathogens are recommended.

Reporting 'number needed to treat' in meta-analyses: a cross-sectional study

AIM

In translating clinical research into practice, the summarization of data from randomized trials in terms of measures of effect to be readily appreciated by the point-of-care clinicians is important. In this context, the body of literature highlighted the 'number needed to treat' as a useful measure. The objectives of our study were to assess how meta-analyses described number needed to treat and corresponding 95% CI, and to explore issues related to reporting number needed to treat in the selected meta-analyses.

METHOD

For an illustration, we searched for the Cochrane systematic reviews and non-Cochrane systematic reviews. Two-stage selection was done to identify eligible studies. First, we fixed a date and then, we searched meta-analyses in PUBMED available on the date fixed. Secondly, we purposively selected five Cochrane systematic reviews and three non-Cochrane systematic reviews, according to our inclusion criteria. The critical appraisal of meta-analyses identified for the current study was done with the 5-item quality checklist introduced to the current analysis.

RESULTS

A total of 8 systematic reviews, 5 Cochrane systematic reviews and 3 non-Cochrane systematic reviews/meta-analyses, were identified for the present study. Of these 8 meta-analyses, some (50%; 4/8) described number needed to treat in the method session of the study. However, the majority (87.5%; 7/8) reported number needed to treat in the results. For the details, 80% in Cochrane reviews and 66.5% in non-Cochrane reviews reported number needed to treat in the results. Only two studies (25%; 2/8) reported susceptibility to publication bias, provided simplified interpretation or discussed number needed to treat.

CONCLUSION

Although the Cochrane handbook for systematic reviews of interventions suggests the reviewers to include number needed to treat in reporting effect estimations, there still is a need to improve.

Inhibitory effects of cytochrome P450 enzymes CYP2C8, CYP2C9, CYP2C19 and CYP3A4 by Labisia pumila extracts

ETHNOPHARMACOLOGICAL RELEVANCE

Labisa pumila (LP), popularly known with its local name, Kacip Fatimah, is a well known herb grown in Indochina and Southeast Asia and is traditionally used to regain energy after giving birth in women. The propensity of LP to cause drug-herb interaction via cytochrome P450 (CYP) enzyme system has not been investigated.

AIM OF THE STUDY

To evaluate the in vitro inhibitory effects of various LP extracts (aqueous, ethanol, dichloromethane (DCM) and hexane) on cytochrome P450 2C8 (CYP2C8), CYP2C9, CYP2C19 and CYP3A4 activities.

MATERIALS AND METHODS

Probe substrate-based high performance liquid chromatography (HPLC) methods were established for CYP2C9, CYP2C19 and CYP3A4 whereas a fluorescence-based enzyme assay was established for CYP2C8. The metabolite formations were examined after incubation of probe substrate with respective CYP isoform in the present or absent of LP extracts. The inhibitory effect of LP was characterized with kinetic parameters IC(50) and K(i) values.

RESULTS

LP extracts showed differential effect of CYP activities with the order of inhibitory potency as follows: dichloromethane>hexane>ethanol>aqueous. This differential effect was only observed in CYP2C isoforms but not CYP3A4. Both the hexane and DCM extracts exhibited moderate to potent inhibition towards CYP2C activities in different modes including non-competitive, competive and mixed-type. The DCM effect was notably strong for CYP2C8 and CYP2C9 showing K(i) values of below 1 μg/ml. The selectivity of LP for CYP2C isoforms rather than CYP3A4 may be attributed to the presence of relatively small, lipophilic yet slightly polar compounds within the LP extracts.

CONCLUSIONS

The results of our study revealed that phytoconstituents contained in LP, particularly in hexane and dichloromethane extracts, were able to selectively inhibit CYP2C isoforms. The inactivation was characterized by low K(i) values, in particular, in CYP2C8 and CYP2C9. These in vitro data indicate that LB preparations contain constituents that can potently inhibit CYP2C activities and suggest that this herb should be examined for potential pharmacokinetic drug interactions in vivo.

Signal detection to identify serious adverse events (neuropsychiatric events) in travelers taking mefloquine for chemoprophylaxis of malaria

BACKGROUND

For all medications, there is a trade-off between benefits and potential for harm. It is important for patient safety to detect drug-event combinations and analyze by appropriate statistical methods. Mefloquine is used as chemoprophylaxis for travelers going to regions with known chloroquine-resistant Plasmodium falciparum malaria. As such, there is a concern about serious adverse events associated with mefloquine chemoprophylaxis. The objective of the present study was to assess whether any signal would be detected for the serious adverse events of mefloquine, based on data in clinicoepidemiological studies.

MATERIALS AND METHODS

We extracted data on adverse events related to mefloquine chemoprophylaxis from the two published datasets. Disproportionality reporting of adverse events such as neuropsychiatric events and other adverse events was presented in the 2 × 2 contingency table. Reporting odds ratio and corresponding 95% confidence interval [CI] data-mining algorithm was applied for the signal detection. The safety signals are considered significant when the ROR estimates and the lower limits of the corresponding 95% CI are ≥2.

RESULTS

Two datasets addressing adverse events of mefloquine chemoprophylaxis (one from a published article and one from a Cochrane systematic review) were included for analyses. Reporting odds ratio 1.58, 95% CI: 1.49-1.68 based on published data in the selected article, and 1.195, 95% CI: 0.94-1.44 based on data in the selected Cochrane review. Overall, in both datasets, the reporting odds ratio values of lower 95% CI were less than 2.

CONCLUSION

Based on available data, findings suggested that signals for serious adverse events pertinent to neuropsychiatric event were not detected for mefloquine. Further studies are needed to substantiate this.

Relationship between hepatitis C virus infection and type 2 diabetes mellitus: meta-analysis

AIM

To investigate the association between hepatitis C infection and type 2 diabetes mellitus.

METHODS

Observational studies assessing the relationship between hepatitis C infection and type 2 diabetes mellitus were identified via electronic and hand searches. Studies published between 1988 to March 2011 were screened, according to the inclusion criteria set for the present analysis. Authors performed separate analyses for the comparisons between hepatitis C virus (HCV) infected and not infected, and HCV infected and hepatitis B virus infected. The included studies were further subgrouped according to the study design. Heterogenity was assessed using I(2) statistics. The summary odds ratios with their corresponding 95% CIs were calculated based on a random-effects model. The included studies were subgrouped according to the study design. To assess any factor that could potentially affect the outcome, results were further stratified by age group (proportion of ≥ 40 years), gender (proportion of male gender), body mass index (BMI) (proportion of BMI ≥ 27), and family history of diabetes (i.e., self reported). For stability of results, a sensitivity analysis was conducted including only prospective studies.

RESULTS

Combining the electronic database and hand searches, a total of 35 observational studies (in 31 articles) were identified for the final analysis. Based on random-effects model, 17 studies (n = 286,084) compared hepatitis C-infected patients with those who were uninfected [summary odds ratio (OR): 1.68, 95% CI: 1.15-2.45]. Of these 17 studies, 7 were both a cross-sectional design (41.2%) and cohort design (41.2%), while 3 were case-control studies (17.6%). Nineteen studies (n = 51,156) compared hepatitis C-infected participants with hepatitis B-infected (summary OR: 1.92, 95% CI: 1.41-2.62). Of these 19 studies, 4 (21.1%), 6 (31.6%) and 9 (47.4%) were cross-sectional, cohort and case-control studies, respectively. A sensitivity analysis with 3 prospective studies indicated that hepatitis C-infected patients had a higher risk of developing type 2 diabetes compared with uninfected controls (summary odds ratio: 1.41, 95% CI: 1.17-1.7; I(2) = 0%). Among hepatitis C-infected patients, male patients (OR: 1.26, 95% CI: 1.03-1.54) with age over 40 years (summary OR: 7.39, 95% CI: 3.82-9.38) had an increased frequency of type 2 diabetes. Some caution must be taken in the interpretation of these results because there may be unmeasured confounding factors which may introduce bias.

CONCLUSION

The findings support the association between hepatitis C infection and type 2 diabetes mellitus. The direction of association remains to be determined, however. Prospective studies with adequate sample sizes are recommended.

Morphological characteristics of developmental stages of Acanthamoeba and Naegleria species before and after staining by various techniques

Seven stains were studied to determine the best color and contrast for staining the developmental stages of free living pathogenic Acanthamoeba and Naegleria species. The acid-fast bacilli stain (AFB) produced a blue color without contrast; trichrome-eosin and modified Field's showed various color contrasts; Giemsa, iron-hematoxylin, modified AFB and Gram produced only one color which distinguished the nucleus, nucleolus, cytoplasm, food- and water-vacuoles. The motile organs (acanthopodia, pseudopodia, lobopodia and flagella) were also clearly differentiated but produced a similar color as the cytoplasm. These motile organelles were first induced by incubating at 37 degrees C for at least 15 minutes and then fixing with methanol in order to preserve the protruding morphology prior to staining. The trichrome-eosin and iron-hematoxylin stains showed good color contrast for detecting all three stages, the trophozoite, cyst and flagellate; Giemsa and Gram stained the trophozoite and flagellate stages; the modified Field's and modified AFB stains stained only the trophozoite stage. Depending on the purpose, all these stains (except the AFB stain) can be used to identify the developmental stages of Acanthamoeba and Naegleria for clinical, epidemiological or public health use.

In vitro modulatory effects of flavonoids on human cytochrome P450 2C8 (CYP2C8)

The inhibitory effects of five flavonoids with distinct chemical classes (flavones [luteolin], flavonols [quercetin and quercitrin], and flavanones [hesperetin and hespiridin]) on cDNA-expressed CYP2C8 were investigated. CYP2C8 was co-expressed with NADPH-cytochrome P450 reductase in Escherichia coli and used to characterise potency and mechanism of these flavonoids on the isoform. Tolbutamide 4-methylhydroxylase, a high-performance liquid chromatography-based assay, was selected as marker activity for CYP2C8. Our results indicated that the flavonoids inhibited CYP2C8 with different potency. The order of inhibitory activities was quercetin > luteolin > hesperetin > hesperidin > quercitrin. All of these compounds however exhibited mechanism-based inhibition. A number of structural factors were found to be important for inhibition; these include the molecular shape (volume to surface ratio), the number of hydroxyl groups as well as glycosylation of the hydroxyl group. Quercetin was the most potent inhibitor among the flavonoids examined in this study, and our data suggest that it should be examined for potential pharmacokinetic drug interactions pertaining to CYP2C8 substrates in vivo.

Antigenic profile of Blomia tropicalis, Aleuroglyphus ovatus and Glycycometus malaysiensis

House dust mites and storage mites are well-known causes for allergenic diseases. The aim of this study was to investigate the immunogenic sites of Blomia tropicalis, Aleurogyphus ovatus and Glycycometus malaysiensis. The mites were maintained in a culture medium at 25ºC and 75% relative humidity. Mites were harvested either with heat escape or floatation method, purified, homogenized, quantified and used for the production of polyclonal antibody and immunostaining. For each species of mites, five male mice and five male rats were randomly selected and immunized intraperitoneally with respective crude mite extract at two-weekly intervals. Blomia tropicalis, A. ovatus or G. malaysiensis whole mites and paraffin-embedded mite sections were immunostained with the respective polyclonal antibody. The faecal pellets of mites were intensely stained for all the three species in the present study. The legs of sectioned A. ovatus were not immunogenic as compared with those of G. malaysiensis and B. tropicalis. The outer layer (cuticle) of whole mites and the eggs for these species were very immunogenic. Hence, the polyclonal antibodies obtained in this study may serve as potential tools in detecting the eggs and immature mites in environmental samples. Future studies should focus on the antigenic components of eggs since they were relatively abundant in dust and highly antigenic as seen in the present study.

Heterologous expression of human cytochromes P450 2D6 and CYP3A4 in Escherichia coli and their functional characterization

This study aimed to express two major drug-metabolizing human hepatic cytochromes P450 (CYPs), CYP2D6 and CYP3A4, together with NADPH-cytochrome P450 oxidoreductase (OxR) in Escherichia coli and to evaluate their catalytic activities. Full length cDNA clones of both isoforms in which the N-terminus was modified to incorporate bovine CYP17α sequence were inserted into a pCWori(+) vector. The modified CYP cDNAs were subsequently expressed individually, each together with OxR by means of separate, compatible plasmids with different antibiotic selection markers. The expressed proteins were evaluated by immunoblotting and reduced CO difference spectral scanning. Enzyme activities were examined using high performance liquid chromatography (HPLC) assays with probe substrates dextromethorphan and testosterone for CYP2D6 and CYP3A4, respectively. Results from immunoblotting demonstrated the presence of both CYP proteins in bacterial membranes and reduced CO difference spectra of the cell preparations exhibited the characteristic absorbance peak at 450 nm. Co-expressed OxR also demonstrated an activity level comparable to literature values. Kinetic parameters, K(m) and V(max) values determined from the HPLC assays also agreed well with literature values. As a conclusion, the procedures described in this study provide a relatively convenient and reliable means of producing catalytically active CYP isoforms suitable for drug metabolism and interaction studies.

Detection of Naegleria species in environmental samples from Peninsular Malaysia

BACKGROUND

In Malaysia, researchers and medical practitioners are unfamiliar with Naegleria infections. Thus little is known about the existence of pathogenic Naegleria fowleri, and the resultant primary amoebic meningoencephalitis (PAM) is seldom included in the differential diagnosis of central nervous system infections. This study was conducted to detect the presence of Naegleria species in various environmental samples.

METHODS/FINDINGS

A total of 41 Naegleria-like isolates were isolated from water and dust samples. All these isolates were subjected to PCR using two primer sets designed from the ITS1-ITS2 regions. The N. fowleri species-specific primer set failed to produce the expected amplicon. The Naegleria genus-specific primers produced amplicons of 408 bp (35), 450 bp (2), 457 bp (2) or 381 bp (2) from all 41 isolates isolated from aquatic (33) and dust (8) samples. Analysis of the sequences from 10 representative isolates revealed that amplicons with fragments 408, 450 and 457 bp showed homology with non-pathogenic Naegleria species, and 381 bp showed homology with Vahlkampfia species. These results concurred with the morphological observation that all 39 isolates which exhibited flagella were Naegleria, while 2 isolates (AC7, JN034055 and AC8, JN034056) that did not exhibit flagella were Vahlkampfia species.

CONCLUSION

To date, pathogenic species of N. fowleri have not been isolated from Malaysia. All 39 isolates that produced amplicons (408, 450 and 457 bp) from the genus-specific primers were identified as being similar to nonpathogenic Naegleria. Amplicon 408 bp from 5 representative isolates showed 100% and 99.7% identity to Naegleria philippinensis isolate RJTM (AM167890) and is thus believed to be the most common species in our environment. Amplicons 450 bp and 457 bp were respectively believed to be from 2 new species of Naegleria, since representative isolates showed lower homology and had a longer base pair length when compared to the reference species in the Genbank, Naegleria schusteri (AJ566626) and Naegleria laresi (AJ566630), respectively.

Molecular identification of house dust mites and storage mites

Mites are known causes of allergic diseases. Currently, identification of mites based on morphology is difficult if only one mite is isolated from a (dust) sample, or when only one gender is found, or when the specimen is not intact especially with the loss of the legs. The purpose of this study was to use polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of the ITS2 gene, to complement the morphological data for the identification of mites to the species level. For this, six species were cultured: Dermatophagoides pteronyssinus, D. farinae, Blomia tropicalis, Tyrophagus putrescentiae, Aleuroglyphus ovatus and Glycycometus malaysiensis. Genomic DNA of the mites was extracted, quantified, amplified and digested individually with restriction enzymes. Hinf I and Ple I differentiated the restriction patterns of D. pteronyssinus and D. farinae. Bfa I and Alu I enzymes differentiated B. tropicalis and G. malaysiensis. Ple I enzyme was useful for the differentiation between T. putrescentiae and A. ovatus. Bfa I was useful for the differentiation of G. malaysiensis from the rest of the species. In conclusion, different species of mites can be differentiated using PCR-RFLP of ITS2 region. With the established PCR-RFLP method in this study, identification of these mites to the species level is possible even if complete and intact adult specimens of both sexes are not available. As no study to date has reported PCR-RFLP method for the identification of domestic mites, the established method should be validated for the identification of other species of mites that were not included in this study.

In vitro effects of active constituents and extracts of Orthosiphon stamineus on the activities of three major human cDNA-expressed cytochrome P450 enzymes

Orthosiphon stamineus (OS) has been traditionally used to treat diabetes, kidney and urinary disorders, high blood pressure and bone or muscular pain. To assess the possibility of drug-herb interaction via interference of metabolism, effects of four OS extracts of different polarity and three active constituents (sinensetin, eupatorin and rosmarinic acid) on major human cDNA-expressed cytochrome P450 (CYP) enzymes were investigated. Three substrate-probe based high-performance liquid chromatography (HPLC) assays were established to serve as activity markers for CYP2C9, CYP2D6 and CYP3A4. Our results indicate that OS extracts and constituents exhibited differential modulatory effects on different CYPs. While none of the OS components showed significant inhibition on CYP2C9, eupatorin strongly and uncompetitively inhibited CYP2D6 activity with a K(i) value of 10.2μM. CYP3A4 appeared to be the most susceptible enzyme to OS inhibitory effects. It was moderately inhibited by OS dichloromethane and petroleum ether extract with mixed-type and noncompetitive inhibitions (K(i)=93.7 and 44.9μg/mL), respectively. Correlation study indicated that the inhibition was accounted for by the presence of eupatorin in the extracts. When IC(50) values of these extracts were expressed in volume per dose unit to reflect inhibitory effect at recommended human doses from commercially available products, moderate inhibition was also observed. In addition, CYP3A4 was strongly and noncompetitively inhibited by eupatorin alone, with a K(i) value of 9.3μM. These findings suggest that co-administration of OS products, especially those with high eupatorin content, with conventional drugs may have the potential to cause drug-herb interactions involving inhibition of major CYP enzymes.

Candida parapsilosis-specific monoclonal antibodies and their use for detection of Candida antigens in experimental systemic candidiasis

Candida parapsilosis has emerged as one of the most common causes of bloodstream infection worldwide. The diagnosis of invasive candidiasis etiological agents to the species level remains a laboratory and clinical challenge. Thus, specific monoclonal antibodies to detect systemic candidiasis and to identify Candida virulence factors and associated pathogenesis through immunohistochemistry would be very useful. Inbred Balb/c mice were immunized with C. parapsilosis antigens, and blood was checked for the presence of reactive antibodies using ELISA. Fusion was performed using the harvested spleen cells and NS1 myeloma cells, and the clones were screened for the presence of antibody producing hybrid cells by dot-blot. The 1B11 clone secreted IgG2a monoclonal antibody that was reactive with the C. parapsilosis antigen at MW of 59 kDa and cross-reacted with C. tropicalis but not with other fungal and bacterial antigens tested. Another 3D1 clone secreted IgG1 monoclonal antibody that was reactive with C. parapsilosis antigen at MW of 30 kDa. The 3D1 monoclonal antibody was found to be species specific. Experimental systemic candidiasis in rats was induced through intravenous injection of C. parapsilosis, and all the vital organs were collected for immunohistochemistry study. These monoclonal antibodies were reactive against surface epitopes on the yeast cells, pseudohyphae, and immune complexes in tissue sections. Sandwich ELISAs using these antibodies were developed and were able to detect circulating antigens in experimental candidiasis in rats at 0.2 μg/μL. These monoclonal antibodies may have potential as primary capture antibodies for the development of rapid diagnostic test for human systemic fungal infection.

In vitro modulatory effects on three major human cytochrome P450 enzymes by multiple active constituents and extracts of Centella asiatica

ETHNOPHARMACOLOGICAL RELEVANCE

Centella asiatica (CA) has been widely cultivated as a vegetable or spice in China, Southeast Asia, India, Sri Lanka, Africa, and Oceanic countries and traditionally used for wound healing and maintaining normal blood pressure.

AIM OF THE STUDY

The present study was carried out to examine the potential modulatory effects of three commercially available active components (asiaticoside, asiatic acid and madecassic acid) and four extracts (aqueous, ethanol, dichloromethane and hexane) of CA on three major cDNA-expressed human cytochrome P450 (CYP) isoforms.

MATERIALS AND METHODS

High-performance liquid chromatography (HPLC)-based enzyme assays, namely tolbutamide 4-methyhydroxylase, dextromethorphan O-demethylase and testosterone 6beta-hydroxylase assays were developed to probe activities of CYP2C9, CYP2D6 and CYP3A4, respectively. Probe substrates were incubated with or without each active component and extract for each isoform, followed by examination of the kinetics parameters, IC(50) and K(i), to characterize modulatory effects.

RESULTS

CYP2C9 was more susceptible to inhibitory effects by CA extracts compared to CYP2D6 and CYP3A4. Moderate degree of inhibition was observed in ethanol (K(i)=39.1 microg/ml) and dichloromethane (K(i)=26.6 microg/ml) extracts implying potential risk of interaction when CYP2C9 substrates are consumed with CA products. The two extracts however showed negligible inhibition towards CYP2D6 and CYP3A4 (IC(50)'s of 123.3 microg/ml and above). Similarly CA aqueous and hexane extracts did not significantly inhibit all three isoforms investigated (IC(50)'s of 117.9 microg/ml and above). Among the active constituents investigated, asiatic acid and madecassic acid appeared to selectively inhibit CYP2C9 and CYP2D6 more than CYP3A4. Of particular interest is the potent inhibitory effect of asiatic acid on CYP2C9 (K(i)=9.1 microg/ml). This signifies potential risk of interaction when substrates for this isoform are taken together with CA products with high asiatic acid content. Inhibitions of asiatic acid with the other isoforms and that of madecassic acid with all isoforms were only moderate (K(i)'s ranged from 17.2 to 84.4 microg/ml). On the other hand, the IC(50) values for asiaticoside were high (1070.2 microg/ml or above) for all three isoforms, indicating negligible or low potential of this compound to modulate CYP enzymatic activity.

CONCLUSION

Centella asiatica extracts and active constituents inhibited CYP2C9, CYP2D6 and CYP3A4 activities with varying potency with CYP2C9 being the most susceptible isoform to inhibition. Significant inhibition was observed for asiatic acid and CA ethanol and dichloromethane extracts, implying involvement of semipolar constituents from CA in the effect. This study suggested that CA could cause drug-herb interactions through CYP2C9 inhibition.