Evaluation of six immunoassays for detection of dengue virus-specific immunoglobulin M and G antibodies

The performance of six commercially available immunoassay systems for the detection of dengue virus-specific immunoglobulin M (IgM) and IgG antibodies in serum was evaluated. These included two IgM and IgG enzyme immunoassays (EIA) from MRL Laboratories and PanBio, a rapid immunochromatographic test (RIT) from PanBio, immunofluorescence assays (IFA) from Progen, a dot blot assay from Genelabs, and a dipstick EIA from Integrated Diagnostics (INDX). For this study a panel of 132 serum samples, including 90 serum samples from patients with suspected dengue virus infection and 42 serum samples from patients with other viral infections, was used. In addition, serial serum samples from two monkeys experimentally immunized and challenged with dengue virus type 2 were used. Results were considered conclusive when concordant results were obtained with four of the six antibody-specific assays. Based on this definition, the calculated overall agreement for the human serum samples for the respective IgM immunoassays was 97% (128 of 132), with 34% (45 of 132) positive serum samples, 63% (83 of 132) negative samples, and 3% of samples (4 of 132) showing discordant results. The calculated overall agreement for the IgG assays was 94% (124 of 132), with 49% (65 of 132) positive, 45% (59 of 132) negative, and 6% (8 of 132) discordant results, respectively. The sensitivities of the dengue virus-specific assays evaluated varied between 71 and 100% for IgM and between 52 and 100% for IgG, with specificities of 86 to 96% and 8

An outbreak of West Nile fever among migrants in Kisangani, Democratic Republic of Congo.

In February 1998, an outbreak of acute febrile illness was reported from the Kapalata military camp in Kisangani, the Democratic Republic of Congo. The illness was characterized by an acute onset of fever associated with severe headache, arthralgia, backache, neurologic signs, abdominal pain, and coughing. In 1 individual, hemorrhagic manifestations were observed. The neurologic signs included an altered level of consciousness, convulsions, and coma. Malaria was initially suspected, but the patients showed negative blood films and failed to respond to antimicrobial drugs. A total of 35 sera collected from the military patients in the acute phase were tested for the presence of IgM against vector-borne agents. Serum IgM antibodies against West Nile fever virus were found in 23 patients (66%), against Chikungunya virus in 12 patients (34%), against dengue virus in 1 patient (3%), and against Rickettsia typhi in 1 patient (3%). All sera were negative for IgM antibody against Rift Valley fever virus, Crimean Congo hemorrhagic fever virus, and Sindbis virus. These data suggest that infections with West Nile fever virus have been the main cause of the outbreak

A New Indirect Spectrofluorimetric Method for Determination of Ascorbic Acid with 2,4,6-Tripyridyl-S-Triazine in Pharmaceutical Samples

Ascorbic acid (AA) is a water-soluble vitamin which shows no fluorescence. However, in reaction with iron(III), AA is oxidised to dehydroascorbic acid and iron(III) is reduced to iron(II) which forms a complex with 2,4,6-tripyridyl-S-triazine (TPTZ) in buffered medium. The relative fluorescence intensity of the resulting Fe(TPTZ)22+ complex can be measured at excitation and emission wavelengths of 393 and 790 nm, respectively. Based on this data, a new indirect spectrofluorimetric method for the determination of AA in pharmaceutical samples was proposed. Influence of the reaction conditions, such as acidity of acetic buffer, concentration of TPTZ and iron(III), reaction time and instrumental parameters were investigated in detail. The linear range was from 5.4 × 10−4 to 5.4 × 10−6 mol·L−1 (R = 0.9971). The LOD was 7.7 × 10−7 mol·L−1 and LOQ was 2.3 × 10−4 mol·L−1. Fourteen pharmaceutical samples containing various amounts of AA were analysed. Influences of potential interfering substances were also examined. Analysis of commercial pharmaceutical formulations showed good correlation with the nominal values given by the manufacturers and with the results obtained by a titration method. The proposed method can be applied in routine quality control in the pharmaceutical industry due to its sensitivity, simplicity, selectivity and low cost

CML – Simulation based software: an effective educational tool for distance learning

Information Technology (IT) education is disrupted by distance learning since it is primarily reliant on hands-on labs and practical experience. In the era of rapid technological change and innovation, the quality of the IT courses offered in higher education is crucial to developing the next generation of IT specialists. In this context, simulation-based software solutions must be adopted immediately to enhance the IT education learning process significantly

A new spectrofluorimetric method for the determination of ascorbic acid with bromocresol purple in pharmaceutical samples

Abstract Based on the interaction between ascorbic acid and bromocresol purple, a new simple, straightforward, and quick method for the quantification of ascorbic acid is proposed. The procedure is based on the determined quenching effect of ascorbic acid on the natural fluorescence signal of bromocresol purple in the reaction between ascorbic acid and bromocresol purple in phosphate buffer solution (pH 6). The reduction of bromocresol purple fluorescence intensity is detected at 641 nm, while excitation occurs at 318 nm. The linear relationship between the reduced fluorescence intensity of bromocresol purple and the concentration of ascorbic acid is in the range 4.65 × 10–5 to 4.65 × 10–6 mol L−1 (R2 = 0.9964), with the detection limit of 8.77 × 10–7 mol L−1 and quantification limit of 2.35 × 10–5 mol L−1. The findings in this study further show that the new method provides good precision and repeatability, as well as satisfactory recovery values in terms of accuracy. The new method is tested on fifteen samples with different amounts of ascorbic acid and additional components. The effects of interfering components such as citrus bioflavonoids, citric acid, folic acid, paracetamol, calcium, and magnesium carbonate on the intensity of fluorescence of bromocresol purple are also investigated. The effects of interfering components such as citrus bioflavonoids (routine and hesperidin), citric acid, folic acid, paracetamol, calcium, and magnesium carbonate on the intensity of fluorescence of bromocresol purple are also investigated. The results of iodometric titration point out that the new method is effective for the determination of ascorbic acid in pharmaceutical samples. Article Highlights A new spectrofluorimetric method for determination of ascorbic acid in pharmaceutical samples using bromocresol purple. Determination of optimal parameters for ascorbic acid determination in a variety of pharmaceutical samples. Examination of the influence of additional substances in the pharmaceutical samples on the analysis. </jats:sec