Highest Number Of Positive Samples Research Articles

Detection of adenovirus and enterovirus by PCR amplification in polluted waters

Several systems for virus recovery from environmental samples and extraction of nucleic acid were tested by adding adenovirus 2 and poliovirus 1 to different sewage samples. The most promising method involved: concentration of viruses by centrifugation, and elution of the pelleted viruses by treatment with 0.25 N glycine buffer pH 9.5. The nucleic acids were extracted by adsorption of RNA and DNA to silica particles. One aliquot was directly used for a two-step PCR in a nested fashion, with specific primers for all adenoviruses; the other aliquot was used to synthesize cDNA and a nested two-step PCR with specific primers for enteroviruses. The specificity and sensitivity of the selected primers were evaluated, the 47 human adenovirus serotypes were identified and 24 different enterovirus strains were recognized. The sensitivity of the nucleic acid extraction, cDNA synthesis and nested PCR amplification was estimated to be between 1 and 10 viral particles. Sewage and polluted river samples were analyzed showing, as expected, a much higher number of positive samples by the method described than by tissue culture analysis, a high prevalence of hepatitis A virus in sewage and the adenoviruses as the most commonly detected virus in the environmental samples analyzed.

Detection of adenovirus and enterovirus by PCR amplification in polluted waters

Several systems for virus recovery from environmental samples and extraction of nucleic acid were tested by adding adenovirus 2 and poliovirus 1 to different sewage samples. The most promising method involved: concentration of viruses by centrifugation, and elution of the pelleted viruses by treatment with 0.25 N glycine buffer pH 9.5. The nucleic acids were extracted by adsorption of RNA and DNA to silica particles. One aliquot was directly used for a two-step PCR m a nested fashion, with specific primers for all adenoviruses; the other aliquot was used to synthesize cDNA and a nested two-step PCR with specific primers for enteroviruses. The specificity and sensitivity of the selected primers were evaluated, the 47 human adenovirus serotypes were identified and 24 different enterovirus strains were recognized. The sensitivity of the nucleic acid extraction, cDNA synthesis and nested PCR amplification was estimated to be between 1 and 10 vital particles. Sewage and polluted river samples were analyzed showing, as expected, a much higher number of positive samples by the method desrnbed than by tissue culture analysis, a high prevalence of hepatitis A virus in sewage and the adenoviruses as the most commonly detected virus in the environmental samples analyzed.

A study of the microbial flora of the anterior vagina of normal sows during different stages of the reproductive cycle.

Sterile guarded swabs were used to sample the anterior vaginal and cervical area of 23 normal healthy sows during various stages of the reproductive cycle. The samples were collected one week before farrowing, within 24 hours of farrowing, weekly up to weaning, at mating and at 2 and 3 weeks after mating, and then plated and incubated aerobically and anaerobically. At least one positive sample was obtained from each sow and at each stage of the reproductive cycle. Most positive samples (78.3%) were obtained on the day of farrowing and the least 3 weeks after mating (19.0%). The second highest number of positive samples (45.5%) was found immediately after mating. Although there was no significant difference among sows of different parities, there was a trend for older sows to have more positive samples after farrowing (84.6%). There was a greater decrease in positive samples after farrowing and after mating among younger sows compared with older sows. A wide range of bacteria including aerobic and anaerobic species, were recovered from 142 isolates. The more representative bacteria were Streptococcus spp (23.2%); Escherichia coli (22.5%); Staphylococcus spp (19.0%) and Corynebacterium spp (13.4%). Of the cultures, 54.7% were pure and 45.3% were mixed. Both the percentage of bacterial isolates as well as the type of culture (pure or mixed) were similar to those frequently reported in clinical cases of vulval discharge syndrome. The results indicate that sows usually develop infections of the reproductive tract at farrowing and mating but these infections do not normally persist.

Diagnostic Sensitivity of Polymerase Chain Reaction and Southern Blot Hybridization for the Detection df Human Papillomavirus DNA in Biopsy Specimens from Cervical Lesions

Human papillomaviruses (HPVs) are associated with benign and malignant neoplasms of the cervix. One of the criteria for their etiologic role requires an assessment of whether virtually all or only a small fraction of lesions contain viral genomes. DNA preparations from colposcopically directed punch biopsies of cervical lesions were analyzed by Southern blot hybridization and the polymerase chain reaction (PCR) for the presence of HPV DNA. The biopsy specimens represented different pathologic entities (koilocytosis, condyloma, cervical intraepithelial neoplasia, and invasive carcinoma). In Southern blot hybridization with radioactive probes for HPV 11, 16, 18, 31, and 33, HPV DNA was detected in 74% of the biopsy specimens (42 of 57 cases), with the predominant types being HPV 16 and HPV 18. In contrast, after PCR amplification with primers yielding fragments of characteristic size for HPV 11, 16, and 18, the analysis of the same 57 biopsy specimens revealed that all samples were positive for at least one HPV type. To exclude false-positive PCR results, controls without HPV DNA were interspersed at regular intervals, and results were evaluated only if these controls remained HPV negative. To exclude false-negative results due to failure of the reaction, a target sequence within the c-Ha-ras-1 gene was used as an internal control. All HPV typing results obtained by Southern blot hybridization were in agreement with HPV typing by PCR. The higher number of positive samples in the latter analysis stems from the increased sensitivity of PCR, which was which was effective in identifying as few as 10-100 HPV DNA molecules; in contrast, the sensitivity of Southern blot hybridization was 1 pg, or approximately 10(5) molecules of HPV DNA. The authors conclude that, with sufficiently sensitive diagnostic methods, HPV DNA can be detected in most, if not all, neoplastic cervical lesions.

Effect of prophylactic cyclosporin on the development of insulin-dependent diabetes mellitus and lymphocytic migration to target organs in autoimmunity in the bb rat

To determine the prevalence of Trichomonas vaginalis (T. vaginalis) in HIV/AIDS patients attending two different hospitals in southeast Nigeria.We collected 970 urine samples from HIV/AIDS patients attending two different hospitals in southeast Nigeria. Samples were processed by microscopy and cultural methods.Out of the 970 screened, 355 (36.60%) were positive for T. vaginalis. Subjects with the least CD4+ count in the range of 40-140 cells/mL had the highest number of positive samples (180, 50.70%), while those in the range of 480-580 cells/mL had the least value (2, 0.56%). Those in the rural areas had a higher number of positive samples (155, 38.75%) than their urban counterparts (200, 35.09%) with respect to the total number examined in each group but this was not statistically significant (P>0.05). Out of the 355 positive cases, the university undergraduate students’ group had the highest percentage incidence of 53.00% followed by the low-income group with 47.08%.It can be concluded that the occurrence of T. vaginalis increases with decrease in the CD4+ counts in HIV/AIDS patients in Nigeria. Since T. vaginalis may be an important cofactor in promoting the spread of HIV and, in some circumstances, may have a major impact on the epidemic dynamics of HIV, there is a need to take measures to check the spread of this parasitic infection.

Effects of Sampling Procedures on Salmonella Recovery from Fresh Water Catfish

To determine the effectiveness of different sampling procedures, 200 frozen catfish known to be contaminated with Salmonella were divided into 350 samples. Variables in sampling included anterior and posterior portions of fish, blending, immersion, swabbing, rinsing and incubation at elevated temperatures. The composite of blended anterior and posterior samples incubated at 43 C and immersion of whole fish incubated at 35 C showed the highest number of positive samples, 50% and 42%, respectively. The contact method of swabbing (14%) and rinsing (14%) were the least effective of the methods examined. The anterior (visceral cavity area) portions of the fish seemed to be more highly contaminated (38% positive) than the posterior portion (26% positive). These data show that the sampling procedure can greatly affect recovery of Salmonella from fresh water catfish. Overall levels of Salmonella were low and the hazards of cross-contamination with other foods seem remote.