Field Evaluation of Xpert HPV Point-of-Care Test for Detection of Human Papillomavirus Infection by Use of Self-Collected Vaginal and Clinician-Collected Cervical Specimens.

The World Health Organization has recommended that testing for high-risk human papillomavirus (HPV) (hrHPV) infection be incorporated into cervical screening programs in all settings worldwide. In many high-burden, low-income countries, it will not be feasible to achieve high cervical screening coverage using hrHPV assays that require clinician-collected samples. We conducted the first evaluation of self-collected vaginal specimens compared with clinician-collected cervical specimens for the detection of hrHPV infection using the Xpert HPV test. Women aged 30 to 54 years attending two well-woman clinics in Papua New Guinea were invited to participate and provided self-collected vaginal and clinician-collected cervical cytobrush specimens. Both specimen types were tested at the point of care by using the Xpert HPV test. Women were given their cervical test result the same day. Those with a positive hrHPV test and positive examination upon visual inspection of the cervix with acetic acid were offered same-day cervical cryotherapy. A total of 1,005 women were enrolled, with 124 (12.3%; 95% confidence interval [CI], 10.3%, 14.4%) being positive for any hrHPV infection. There was a 99.4% overall percent agreement (OPA) between vaginal and cervical tests for HPV-16 (95% CI, 98.9%, 99.9%), a 98.5% OPA for HPV-18/45 (95% CI, 97.7%, 99.3%), a 94.4% OPA for other hrHPV infections (95% CI, 92.9%, 95.9%), and a 93.4% OPA for all hrHPV types combined (95% CI, 91.8%, 95.0%). Self-collected vaginal specimens had excellent agreement with clinician-collected cervical specimens for the detection of hrHPV infection using the Xpert HPV test. This approach provides for the first time an opportunity to incorporate point-of-care hrHPV testing into clinical cervical screening algorithms in high-burden, low-income settings.

A diagnostic evaluation of a molecular assay used for testing and treating anorectal chlamydia and gonorrhoea infections at the point-of-care in Papua New Guinea.

OBJECTIVES: Papua New Guinea has among the highest prevalences of sexually transmissible infections (STIs) globally with no services able to accurately test for anorectal Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) infections. Here we prospectively evaluated the diagnostic performance of a molecular CT/NG assay used at the point-of-care (POC) with the aim of enhancing anorectal STI screening and same-day treatment. METHODS: Men who have sex with men, transgender women and female sex workers taking part in Papua New Guinea's first large-scale biobehavioural study were enrolled and asked to provide a self-collected anorectal swab for POC GeneXpert CT/NG testing. Same-day treatment was offered if positive. A convenience sample of 396 unique and randomly selected samples were transported to Australia for comparison using the Cobas 4800 CT/NG test (Roche Molecular Diagnostics, Pleasanton, CA, USA). RESULTS: A total of 326 samples provided valid results by Cobas whereas 70 samples provided invalid results suggesting inhibition. The positive, negative and overall percentage agreements of GeneXpert CT/NG for the detection of C. trachomatis were 96.7% (95% CI 92.3%-98.9%), 95.5% (95% CI 91.3%-98.0%) and 96.0% (95% CI 93.3%-97.8%), and for N. gonorrhoeae were 93.0% (95% CI 86.1%-97.1%), 100.0% (95% CI 98.3%-100.0%) and 97.8% (95% CI 95.6%-99.1%), respectively. CONCLUSIONS: The overall rate of agreement between the GeneXpert and Cobas CT/NG assays was high with 96.0% for C. trachomatis and 97.8% for N. gonorrhoeae. Results from this study data suggest that the GeneXpert CT/NG assay is suitable for testing self-collected anorectal specimens at the POC and that same-day treatment was feasible.

Differential expression of three members of the AMT1 gene family encoding putative high-affinity NH4+ transporters in roots of Oryza sativa subspecies indica.

In order to investigate the molecular basis of high-affinity ammonium absorption by roots of rice plants (Oryza sativa subspecies indica) the expression patterns of three members of the AMT1 family of genes in rice seedling roots in response to altered nitrogen provision and diurnal changes in irradiance were examined. The 13NH4+ influx and transcript levels of OsAMT1.1 in roots decreased several fold within 48 h when plants acclimated to 10 micro m external NH4+ for 3 weeks were transferred to 10 mm NH4+. Likewise when plants acclimated in 10 mm NH4+ were transferred to 10 micro m NH4+, there was an equally rapid up-regulation of OsAMT1.1 and 13NH4+ influx in the roots. Changes in transcript abundance of OsAMT1.2 following these treatments were approximately 50% less than in OsAMT1.1, and changes of OsAMT1.3 expression were even less. By contrast, in response to the diurnal changes of irradiance, root transcript abundance of OsAMT1.3 and 15NH4+ influx increased approximately three-fold late in the photoperiod, whereas OsAMT1.1 and OsAMT1.2 exhibited only modest changes. The present results suggest that high-affinity NH4+ influx is differentially regulated at the transcriptional level through the expression of three members of the OsAMT1 family of genes in roots of rice seedlings in response to changes of N status and daily irradiance. In general, these findings are in agreement with earlier observations in Arabidopsis and tomato.

Plasticity in water-use efficiency of Picea sitchensis, P. glauca and their natural hybrids.

Plasticity in water-use efficiency (WUE) was examined in populations of Picea glauca (Moench) Voss and P. sitchensis (Bong.) Carr. and their natural hybrids from an ecocline along the Skeena Valley, British Columbia, which runs from the dry continental interior (P. glauca) to the wet maritime Pacific coast (P. sitchensis). Seedlings were grown in a growth chamber and kept well-watered or repeatedly droughted for 3 months. Mean population photosynthetic WUE and total tissue δ(13)C values were strongly correlated within and across treatments (r=0.95). There were also strong correlations (r=0.60-0.80) between individual seedling total tissue δ(13)C and dry mass, and δ(13)C and net photosynthesis (A), indicating that variation in A was primarily responsible for differences in δ(13)C. When kept well-watered, P. sitchensis and the hybrids had higher δ(13)C (-27.8‰ and -27.5‰, respectively) and higher dry mass (2.17 g and 1.99 g, respectively) than P. glauca (-28.2‰ and 1.68 g). Species ranking was reversed by repeated drought, with P. glauca and the hybrids having higher δ(13)C (-25.6‰ and -25.5‰, respectively) and dry mass (1.10 g and 1.08 g, respectively) than P. sitchensis (-26.4‰ and 0.98 g). P. glauca had a smaller decrease in dry mass (35%) and a bigger increase in δ(13)C (by 2.7‰) than P. sitchensis (55% and 1.4‰, respectively), with the hybrids in between (45% and 2.0‰, respectively). Drought also had a greater effect on A in P. sitchensis (36% reduction) than in P. glauca (14% reduction) or the hybrids (24% reduction). Thus P. glauca and, to a lesser extent, hybrid populations, performed better and were more plastic than P. sitchensis in response to water deficit. Under the well-watered treatment, the hybrids behaved more like P. sitchensis in growth and WUE. These patterns are consistent with the seasonal variation in moisture availability that occurs along the introgression zone.

AtAMT1 gene expression and NH4+ uptake in roots of Arabidopsis thaliana: evidence for regulation by root glutamine levels.

The mechanisms involved in regulating high-affinity ammonium (NH4+) uptake and the expression of the AtAMT1 gene encoding a putative high-affinity NH4+ transporter were investigated in the roots of Arabidopsis thaliana. Under conditions of steady-state nitrogen (N) supply, transcript levels of the AtAMT1 gene and Vmax values for high-affinity 13NH4+ influx were inversely correlated with levels of N provision. Following re-supply of NH4NO3 to N-starved plants, AtAMT1 mRNA levels and 13NH4+ influx declined rapidly but remained high when the conversion of NH4+ to glutamine (Gln) was blocked with methionine sulfoximine (MSX). This result demonstrates that end products of NH4+ assimilation, rather than NH4+ itself, are responsible for regulating AtAMT1 gene expression. Consistent with this hypothesis, AtAMT1 gene expression and NH4+ influx were suppressed by provision of Gln alone, or together with NH4NO3 plus MSX. Furthermore, AtAMT1 transcript levels and 13NH4+ influx were negatively correlated with root Gln concentrations, following re-supply of N to N-starved plants. In addition to this level of control, the data suggest that high cytoplasmic [NH4+] may inhibit NH4+ influx.