Development of a new ultra sensitive real-time PCR assay (ultra sensitive RTQ-PCR) for the quantification of HBV-DNA

<p>Abstract</p> <p>Background</p> <p>Improved sensitivity of HBV-DNA tests is of critical importance for the management of HBV infection. Our aim was to develop and assess a new ultra sensitive in-house real-time PCR assay for HBV-DNA quantification (ultra sensitive RTQ-PCR).</p> <p>Results</p> <p>Previously used HBV-DNA standards were calibrated against the WHO 1^stInternational Standard for HBV-DNA (OptiQuant^®HBV-DNA Quantification Panel, Accrometrix Europe B.V.). The 95% and 50% HBV-DNA detection end-point of the assay were 22.2 and 8.4 IU/mL. According to the calibration results, 1 IU/mL equals 2.8 copies/mL. Importantly the clinical performance of the ultra sensitive real-time PCR was tested similar (67%) to the Procleix Ultrio discriminatory HBV test (dHBV) (70%) in low-titer samples from patients with occult Hepatitis B. Finally, in the comparison of ultra sensitive RTQ-PCR with the commercially available COBAS TaqMan HBV Test, the in-house assay identified 94.7% of the 94 specimens as positive versus 90.4% identified by TaqMan, while the quantitative results that were positive by both assay were strongly correlated (<it>r </it>= 0.979).</p> <p>Conclusions</p> <p>We report a new ultra sensitive real time PCR molecular beacon based assay with remarkable analytical and clinical sensitivity, calibrated against the WHO 1^stInternational standard.</p

Limited cross-border infections in patients newly diagnosed with HIV in Europe

Matti Ristola ja Jussi Sutinen kuuluvat työryhmään SPREAD ProgrammePeer reviewe

Critical analysis of strength estimates from maturity functions

Strength estimates from the following maturity functions: Nurse-Saul, Rastrup, Weaver and Sadgrove, Freiesleben Hansen and Pedersen, and the Dutch Weighted Maturity have been compared with actual strengths of concretes cured with temperature histories of in-situ blocks, adiabatic and isothermal 50 °C curing. Three concrete mixes with a 28-day nominal cube compressive strength of 50 MPa have been investigated in this work. The first was a neat Portland cement mix whilst the other included partial cement replacement with fly ash (FA) and ground granulated blast furnace slag (GGBS) at 30 and 50% cement replacement levels respectively. High early age temperatures, such as those occurring in adiabatic or isothermal tests, appear to affect adversely the strength estimates and this is believed to be due to the detrimental effect of high curing temperatures on strength starting from a very early age. None of the maturity functions accounts for the detrimental effect of high curing temperatures on later age strength and thus all of them overestimate the later age strengths. It is believed that consideration of this detrimental effect in the maturity functions will improve the strength estimates for both early and later ages. Keywords: Maturity functions, Adiabatic curing, Isothermal curing, In-situ temperature, Strength estimates, Additions, Supplementary cementitious material

Effect of in situ temperature on the early age strength development of concretes with supplementary cementitious materials

A UK based project which involved casting of blocks, walls and slabs, during winter and summer, provided in situ temperature histories that could be simulated in the laboratory using a computer controlled temperature match curing tank. The concretes which were of 28-day target mean strengths of 50 and 30 MPa also had partial cement replacement with supplementary cementitious materials (SCMs) such as ground granulated blast-furnace slag (GGBS) and pulverised fuel ash (PFA). The SCMs were effective in reducing the peak temperature especially when there was heat dissipation. The contribution to early age strength by SCMs increased with the high in situ temperatures especially in blocks cast during summer. The accuracy of strength estimates obtained from maturity functions was examined. The temperature dependence of the Nurse–Saul function was not sufficient to account for the improvement in early age strengths resulting from the high temperatures in blocks cast during summer. The Arrhenius based function, was better at estimating the early age strengths as it assumes that the concrete strength gain rate varies exponentially with temperature

Compressive strength estimates of adiabatically cured concretes using maturity methods

The strength development of standard and adiabatically cured concretes was determined. The concrete mixes were of 28-day cube strengths of 50 and 30 MPa and also had Portland cement (PC) replaced partially with fly ash (FA) and ground granulated blast-furnace slag (GGBS) at 30% and 50%, respectively. The peak adiabatic temperature was effectively reduced with GGBS addition but was only reduced with FA addition for the lower w/b concrete. Considerable early age strength enhancements resulted from the adiabatic curing regime. The Nurse-Saul and Arrhenius based maturity functions were used to estimate the increases in early age adiabatic strength. The Nurse-Saul function underestimated the effect of high early age curing temperature for all concretes but to a greater extent for those with GGBS and FA whilst the Arrhenius based, which allows for the consideration of an “apparent” activation energy, gave more accurate estimates. Strength estimates for adiabatically cured concretes and isothermally (50 °C) cured mortars were also compared indicating that the latter might have been affected by the detrimental effect of high curing temperatures starting from early age