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Omar N.,National Public Health Laboratory | Bakar J.,University Putra Malaysia | Muhammad K.,University Putra Malaysia
Food Control

Pacific white shrimp (Litopenaeus vannamei) collected during dry and rainy seasons from three different states in Malaysia were analyzed for nine organochlorine pesticides (OCPs) (α-HCH, β-HCH, γ-HCH, δ-HCH, trans-chlordane, cis-chlordane, p,p'-DDE, p,p'-DDD and p,p'-DDT) using QuEChERS sample preparation method and GC-MS SIM with split/splitless injection mode. The efficiency of combination of primary and secondary amine (PSA) and octadecyl (C18) at 25mg of PSA and 25mg of C18 per mL of shrimp extract as the clean-up sorbent to remove matrix interferences was evaluated. By combining PSA and C18, matrix interferences such as gamma-tocopherol and cholesterol were not able to be eliminated. Good separation and high recoveries which ranged from 90 to 105% with associated RSD<15% were obtained for all OCPs at 3-75ng/g. No significant difference in recoveries due to seasonal variation for studied OCPs, except for α-HCH, β-HCH, δ-HCH and p,p'-DDT were obtained. The limits of detection and quantification ranged from 0.3 to 4.5ng/g and 3 to 15ng/g, respectively. The linearity for matrix matched standard calibrations was >0.99. © 2013 Elsevier Ltd. Source

Tate M.D.,Monash Institute of Medical Research | Job E.R.,University of Melbourne | Deng Y.-M.,Peter Doherty Institute for Infection and Immunity | Gunalan V.,Agency for Science, Technology and Research Singapore | And 5 more authors.

Seasonal influenza A viruses (IAV) originate from pandemic IAV and have undergone changes in antigenic structure, including addition of glycans to the hemagglutinin (HA) glycoprotein. The viral HA is the major target recognized by neutralizing antibodies and glycans have been proposed to shield antigenic sites on HA, thereby promoting virus survival in the face of widespread vaccination and/or infection. However, addition of glycans can also interfere with the receptor binding properties of HA and this must be compensated for by additional mutations, creating a fitness barrier to accumulation of glycosylation sites. In addition, glycans on HA are also recognized by phylogenetically ancient lectins of the innate immune system and the benefit provided by evasion of humoral immunity is balanced by attenuation of infection. Therefore, a fine balance must exist regarding the optimal pattern of HA glycosylation to offset competing pressures associated with recognition by innate defenses, evasion of humoral immunity and maintenance of virus fitness. In this review, we examine HA glycosylation patterns of IAV associated with pandemic and seasonal influenza and discuss recent advancements in our understanding of interactions between IAV glycans and components of innate and adaptive immunity. © 2014 by the authors; licensee MDPI, Basel, Switzerland. Source

Thakur S.,National College NIST | Pokhrel N.,National College NIST | Sharma M.,National Public Health Laboratory
Research Journal of Pharmaceutical, Biological and Chemical Sciences

Urinary tract infection is major health problem in Nepal. Considering, the majority of infection cases caused by Enterobacteriaceae with Escherichia coli being a major pathogen, the present study was carried out to investigate and identify the Multidrug Resistant pattern of Enterobacteriaceae and Extended Spectrum β- lactamase producing Escherichia coli so that effective strategy for the urinary tract infection treatment can be achieved. A total of 650 specimens were processed at National Public health laboratory (NPHL), Kathmandu Nepal between November 2010 to April 2011. Extended Spectrum β- lactamase screening among multidrug resistant isolates was done using Ceftriaxone, Aztreonam, Cefotaxime, Ceftazidime and Cefpodoxime followed by confirmation using MASTDISCTMID D6. Data analysis was done by SPSS 16 software. Enterobacteriaceae remain predominant of the total isolates (78.7%) of which, Escherichia coli was the most common organism with (64.0%) followed by Klebsiella species (17.9%).Among the total 42 multidrug resistant Escherichia coli subjected for Extended Spectrum β-lactamase screening test 18(31.57%) were confirmed as Extended Spectrum β- lactamase producer by at least one combined disk assay. All the isolates were sensitive to Imipenem (100%) followed by Meropenem (94.44%). Source

Elduma A.H.,National Public Health Laboratory
Pan African Medical Journal

Background: This study was conducted to evaluate the biosafety precautions that applied by diagnostic laboratories in Khartoum state, 2009. Methods: A total number of 190 laboratories were surveyed about their compliance with standard biosafety precautions. These laboratories included 51 (27%) laboratories from government, 75 (39%) from private sectors and 64 (34%) laboratories belong to organization providing health care services. Results: The study found that 32 (16.8%) of laboratories appointed biosafety officers. Only, ten (5.2%) participated in training about response to fire emergency, and 28 (14.7%) reported the laboratory accident occurred during work. 45 (23.7%) laboratories had a written standard operation procedures (SOPs), and 35 (18.4%) had written procedures for the lean-up of spills. Moreover, biosafety cabinet was found in 11 (5.8%) laboratories, autoclave in 28 (14.7%) and incinerator in only two (1.1%) laboratories. Sharp disposable containers were found in 84 (44.2%). Fire alarm system was found in 2 (1.1%) laboratories, fire extinguisher in 39 (20.5%) laboratories, and fire emergency exit found in 14 (7.4%) laboratories. Furthermore, 19 (10%) laboratories had a hepatitis B virus vaccination programme, 5 (6.2%) applied BCG vaccine, and 2 (1.1%0) vaccinated the staff against influenza. Conclusion: The study concluded that the standards biosafety precautions adopted by the diagnostic laboratories in Khartoum state was very low. Further, the laboratory personnel awareness towards biosafety principles implementation was very low too. © Adel Hussein Elduma et al. Source

Moi M.L.,Japan National Institute of Infectious Diseases | Lim C.-K.,Japan National Institute of Infectious Diseases | Chua K.B.,National Public Health Laboratory | Takasaki T.,Japan National Institute of Infectious Diseases | Kurane I.,Japan National Institute of Infectious Diseases
PLoS Neglected Tropical Diseases

Background: Progress in dengue vaccine development has been hampered by limited understanding of protective immunity against dengue virus infection. Conventional neutralizing antibody titration assays that use FcγR-negative cells do not consider possible infection-enhancement activity. We reasoned that as FcγR-expressing cells are the major target cells of dengue virus, neutralizing antibody titration assays using FcγR-expressing cells that determine the sum of neutralizing and infection-enhancing activity, may better reflect the biological properties of antibodies in vivo. Methods and Findings: We evaluated serum samples from 80 residents of a dengue endemic country, Malaysia, for neutralizing activity, and infection-enhancing activity at 1:10 serum dilution by using FcγR-negative BHK cells and FcγR-expressing BHK cells. The serum samples consisted of a panel of patients with acute DENV infection (31%, 25/80) and a panel of donors without acute DENV infection (69%, 55/80). A high proportion of the tested serum samples (75%, 60/80) demonstrated DENV neutralizing activity (PRNT 50≥10) and infection-enhancing activity. Eleven of 18 serum samples from patients with acute secondary DENV infection demonstrated neutralizing activity to the infecting serotype determined by using FcγR-negative BHK cells (PRNT 50≥10), but not when determined by using FcγR-expressing cells. Conclusion: Human serum samples with low neutralizing activity determined by using FcγR-negative cells showed DENV infection-enhancing activity using FcγR-expressing cells, whereas those with high neutralizing activity determined by using FcγR-negative cells demonstrate low or no infection-enhancing activity using FcγR-expressing cells. The results suggest an inverse relationship between neutralizing antibody titer and infection-enhancing activity, and that neutralizing activity determined by using FcγR-expressing cells, and not the activity determined by using FcγR-negative cells, may better reflect protection to DENV infection in vivo. © 2012 Moi et al. Source

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