Detection of anti-HIV-1 IgG antibodies in whole saliva by GACELISA and Western blot assays

The present study, based on 158 HIV seropositives and 167 HIV seronegatives, demonstrates that saliva collected with the Omni-SAL device and tested with GACELISA (an IgG antibody capture ELISA) is an effective non-invasive alternative to serum for anti-HIV IgG antibody screening. The study also shows that a conventional serum Western blot kit can be used, with slight modifications, for confirmatory testing of saliva specimens. Collecting saliva with the Omni-SAL device had a very good acceptance rate among Tanzanian subjects, and although this diagnostic method is not yet known by the general public, 65% of the study participants preferred to give saliva instead of blood for HIV testing.     

Degradation kinetics of ascorbic acid during ohmic heating with stainless steel electrodes

Ascorbic acid degradation experiments were performed in buffer solution at pH 3.5 using a batch ohmic heater with uncoated stainless steel electrodes. The electrical conductivity of the buffer solution was adjusted using sodium chloride. The concentration of ascorbic acid was found using an HPLC technique. Kinetics of degradation can be described adequately by a first order model for both conventional and ohmic treatments, but unlike conventional heating, the temperature dependence of degradation for some ohmic treatments cannot be represented by the Arrhenius relation. During ohmic heating, power, temperature and NaCl content affect the degradation rate. A number of reactions, including electrode reactions, electrolysis of the solution, as well as reactions between electrode materials and electrolysis products may influence the reaction mechanism as well as kinetic parameters. At the highest power and salt content, citrate complexation and a significant loss of buffering capacity were noted, resulting in an increase in pH. The results underline the importance of inert electrode coatings, or the use of high frequency power for control of electrochemical reactions.     

The effect of limited exposure to antimycotics on the relative cell-surface hydrophobicity and the adhesion of oral Candida albicans to buccal epithelial cells

Candida albicans is the major aetiological agent of oral candidosis. Adhesion to oral mucosal surfaces is considered a prerequisite for its successful colonization and subsequent infection, and its relative cell-surface hydrophobicity (CSH) is a contributory physical force. Thus, the main aim here was to determine the CSH of 10 isolates of oral C. albicans after a short exposure to sublethal concentrations of four antifungal agents and to correlate these findings with their adhesion to human buccal epithelial cells (BEC). The yeasts were exposed to sublethal concentrations of nystatin [x 6 minimal inhibitory concentration (MIC)], 5-fluorocytosine (x 8 MIC), ketoconazole (x 4 MIC) and fluconazole (x 4 MIC) for 1 h. The drug was then removed, and the CSH and BEC adhesion assessed by a biphasic aqueous-hydrocarbon assay and a microscopic method, respectively. The mean percentage reductions of CSH after exposure to nystatin, 5-fluorocytosine, ketoconazole and fluconazole were 27.14% (p = 0.01), 9.46% (p = 0.43), 19.47% (p = 0.04) and 6.16% (p = 0.59). Similarly, exposure to all the drugs except 5-fluorocytosine resulted in a significant inhibition of yeast adhesion to BEC, with nystatin eliciting the highest and fluconazole the least inhibition. Further, on regression analysis a strong positive correlation was observed between CSH and adhesion to BEC after limited exposure to 5-fluorocytosine (r = 0.48, p < 0.0001), ketoconazole (r = 0.48, p < 0.0001), fluconazole (r = 0.55, p < 0.0001) as well as in the unexposed controls (r = 0.41, p = 0.001), although nystatin was an exception (r = 0.09, p = 0.44). Taken together, these data elucidate further mechanisms by which antimycotics may operate in vivo to suppress candidal pathogenicity.     

Clinical predictors of HIV-1 infection among preschool children in Dar es Salaam, Tanzania

Seroprevalence of HIV-1 infection was determined in children aged between eighteen months and five years, attending maternal and child health (MCH) clinics in Dar es Salaam, Tanzania. A total of 889 children were eligible for the study, however seven children could not be enrolled because their mothers/guardians absconded and blood could not be drawn from 21 children due to refusal of mothers/guardians and from another 12 children due to technical reasons. Therefore, the participation rate was 95.5%. Of the 849 children screened, 14 (1.65%) were found to have IgG anti HIV-1 antibodies in their sera. The main clinical features found in children with symptomatic HIV-1 disease were weight loss, generalized lymphadenopathy, recurrent fevers, and prolonged diarrhoea. The utility of clinical features suggestive of HIV-1 infection (according to CDC classification) in identifying HIV-1 infection in children was evaluated and found to have high sensitivity (100%), specificity (96.9%) and negative predictive value (100%), but a low positive predictive value (35%). Marked variations in progression to symptomatic phase were noted, whereby some relatively young children had progressed to symptomatic phase (CDC class P-2A), while some older children were still in the asymptomatic stage (CDC class P-1 C). None of the symptomatic HIV-1 infected children presented with neurological disease, severe opportunistic infections, or malignancies. Although reduced mid-upper arm circumference and weight-for-age were associated with HIV seropositivity, these clinical parameters had low positive predictive values compared to the CDC classification.     

Oral endotoxin in healthy adults

A case is presented which is thought to be the first described example of rib fracture occurring as a result of airbag inflation. It would appear that the propellant cartridge came loose during deployment to form a missile, striking the patient on his chest and fracturing a rib.     

THE ASYMPTOTIC PROPERTIES OF THE SAMPLE AUTOCORRELATIONS FOR A MULTIPLE AUTOREGRESSIVE PROCESS WITH ONE UNIT ROOT

Abstract. In this paper the large sample behaviour of the sample autocorrelation matrix R _n( h ), ( h being the lag, n the sample size), of a multivariate autoregressive time series with one of its characteristic roots equal to unity and the rest of the roots lying inside the unit circle is studied. It is shown that R _n( h ) converges almost surely to a constant matrix. Further, the asymptotic distribution of R _n( h ) is characterized as that of a random matrix which is a function of jointly normal random variables.     

Oral Candida infections--a review

Candida species are the commonest agents of oral mycoses. They cause a variety of diseases including the new variant, erythematous candidosis, which is frequently described in HIV infection. Due to these and other reasons the classification of oral candidosis has been recently revised, and further more new therapeutic regimes have been described. Hence in this article an overview of oral Candida infections is presented with special emphasis on current concepts related to classification and treatment.     

Pulsed power production of ozone in O2/N2 ina coaxial reactor without dielectric layer

Very short duration pulsed streamer discharges have been used to produce ozone in a gas mixture of nitrogen and oxygen at atmospheric pressure. The ratio of nitrogen to oxygen in the mixture was varied in the range from 2.5/0.5 to 0.5/2.5, while maintaining a total flow rate of 3 l/min. The production of ozone was found to be higher for a specific mixture ratio of N₂/O₂ than that in oxygen or in dry air. The production of ozone in O₂ was higher than that in dry air. The production yield of ozone (g/kWh) increased with decreasing nitrogen in the O₂/N₂ mixture. It has been found that the peak of the streamer discharge current decreased with time after application of the pulsed power. This decrease in the current corresponded with the increase in the ozone production and is attributed to the loss of electrons in the discharge current due to their attachment to ozone to form negative ions     

Adhesion of oral Candida albicans isolates to denture acrylic following limited exposure to antifungal agents

Candidal adherence to denture acrylic surfaces is implicated as the first step in the pathogenesis of Candida-associated denture stomatitis, the most prevalent form of oral candidosis in the West. This condition is treated by topically administered antifungal agents, mainly belonging to the polyenes and azoles. As the intraoral concentrations of antifungals fluctuate considerably due to the dynamics of the oral environment, the effect of short exposure to sublethal concentrations of antifungals on the adhesion of Candida albicans to denture acrylic surfaces was investigated. Seven oral C. albicans isolates were exposed to four-eight times minimum inhibitory concentrations (MIC) of five antifungal drugs, nystatin, amphotericin B, 5-fluorocytosine, ketoconazole and fluconazole, for 1 h. After removing the drug (by repeated washing) the adhesion of these isolates to acrylic strips was assessed by an in vitro adhesion assay. Exposure to antifungal agents significantly reduced the adherence of all seven C. albicans isolates to denture acrylic. The mean percentage reductions of adhesion after limited exposure to nystatin, amphotericin B, 5-fluorocytosine, ketoconazole and fluconazole were 86.48, 90.85, 66.72, 65.88 and 47.42%, respectively. These findings indicate that subtherapeutic doses of antifungals may modulate oral candidal colonization. Further, these results may have an important bearing on dosage regimens currently employed in treating oral candidosis.