Evaluation of pooled screening for anti-HCV in two blood services set-ups.

OBJECTIVE: Screening blood donations for anti-HCV is only partially performed in many developing countries due to the relatively high costs of testing. The screening expenditures can be reduced by testing donations in pools. This study evaluates the accuracy and feasibility of pooled screening procedure for anti-HCV in blood banks in Israel and the Palestinian Authority. METHODS: The sensitivity and specificity of tests performed on pool sizes of 6-24 samples were compared to singleton immunoassay testing. All negative samples and those positive for anti-HCV were obtained from the routine work of Magen David Adom Blood Services in Israel and Shifa Hospital blood bank in Palestinian Authority. The experiments were run in parallel with different technologies. RESULTS: The sensitivity of pooled-testing for anti-HCV by Magen David Adom was 94-97% for verified samples. In the Shifa Hospital, the sensitivity was estimated as 96-97% for non-verified samples. Cost-analysis showed benefits up to $2 per donation screened for anti-HCV in Shifa Hospital. CONCLUSIONS: We recommend using manually created pools of up to 6 samples when testing for anti-HCV, but at the cost of 3% loss in sensitivity. Pooling can be considered, in countries which do not perform routine screening, due to their limited economic resources.

Accuracy of hepatitis C virus core antigen testing in pools among seroconverters.

BACKGROUND: Screening blood units for hepatitis C virus (HCV) with nucleic acid testing (NAT) reduces the risk associated with the long "window period" (8-9 weeks) after HCV infection. The feasibility of adding the HCV core antigen assay in pools to the existing anti-HCV individual screening was examined as an alternative of NAT, for early detection of HCV. STUDY DESIGN AND METHODS: Eighteen HCV seroconversion panels were tested for HCV antibodies, HCV antigen, and HCV RNA. Each sample was tested for HCV antigen individually and in pools of 3, 6, and 12. Statistical analyses included estimation of time until detection of the first positive HCV antigen bleed in each pool size, with a locally weighted regression (LOWESS) model. Sensitivity was calculated compared to NAT. RESULTS: Detection of HCV antigen in individual samples and in pools of 3 and 6 significantly preceded the detection of antibodies by 63, 53, and 46 days, respectively. Although the sensitivity of the HCV antigen test decreased with the increase in pool size, the estimated overall sensitivity of the "two-stage" antigen and antibody screening (where NAT of individual samples was the gold standard) was not significantly different between individual and the different pool sizes. CONCLUSION: Screening for HCV antigen in pools of 6 can be considered an efficient and easier-to-implement alternative to the costly NAT for identifying blood donors in the seroconversion period. It may offer a cost-effective approach in resource utilization in poor countries, that, after the implementation of HCV antibody testing, want to further improve blood safety.

Use of seroconversion panels to estimate delay in detection of anti-human immunodeficiency virus antibodies by enzyme-linked immunosorbent assay of pooled compared to singleton serum samples.

The transfusion of unsafe blood worldwide accounts for 5 to 15% of new human immunodeficiency virus (HIV) infections, most of which occur in sub-Saharan Africa. While developed countries now apply PCR testing of pooled samples, some developing countries still do not have universal screening policies. More efficient low-cost procedures for the screening of pooled samples have the potential to encourage mass screening efforts in resource-poor settings. The aim of this study was to estimate the delay in the detection of HIV antibodies in pooled serum samples compared to that in singleton serum samples by enzyme-linked immunosorbent assay (ELISA) and to evaluate the risk of transfusion-transmitted HIV infection during the window period. Serial blood samples obtained from five HIV seroconversion panels were mixed with HIV-seronegative blood samples to create pools of 6, 12, 16, 24, 32, and 48 samples. The delay in detection of the first anti-HIV antibody-positive sample in tests with pooled samples was calculated for each pool size and compared to that obtained by testing of singleton samples and statistically evaluated by a robust log-linear regression analysis. The risk of a false-negative (FN) result caused by dilution was estimated by use of the incidence risk/window period model. The additional risk of transmission related to ELISA screening of pooled samples for HIV did not exceed 9% of the current risk of an FN result (estimated to be 1/1,067,000). The countries with virus prevalence rates in donors of less than 15% are expected to save up to 30% in the number of tests. ELISA screening of pooled samples could be considered in settings where the testing of blood supplies for HIV is not routinely done.

Psammomys obesus (sand rat), a new animal model of non-alcoholic fatty liver disease.

BACKGROUND/AIMS: Non-alcoholic fatty liver disease (NAFLD) is an increasingly recognized condition that includes a spectrum of clinicopathologic conditions ranging from steatotosis to cirrhosis and liver failure. NAFLD is usually associated with features of the metabolic syndrome. No established therapies can be offered to patients with NAFLD. An appropriate animal model of NAFLD would be of help in understanding the mechanisms of the disease and in testing novel therapeutic modalities. Available animal models, such as ob/ob and db/db mice, are unsatisfactory since they show only partial resemblance to human NAFLD. Psammomys obesus (sand rat) is a well-established model of type-2 diabetes and obesity, which shares most metabolic parameters of the human metabolic syndrome. In the present study, we hypothesized that P. obesus will also show features of non-alcoholic fatty liver disease. METHODS: Experimental and control animals were fed normal rat chow or either chow to which fiber (30% wheat straw) was added for 6-18 weeks. Body weight and capillary glucose were measured regularly. At sacrifice blood samples, liver and epididymal fat were obtained. Histology of the liver was blindly determined by a pathologist. RESULTS: The experimental group showed increased body weight, liver and abdominal fat pad mass, raised plasma glucose, insulin and lipids. Also, alanine-aminotransferase (189+/-76 IU versus 86+/-26 IU; p<0.0001) was significantly higher in the experimental than the control group. Microscopic examination of liver tissue demonstrated marked macrovesicular fat infiltration in the experimental group while it was histologicaly normal in the control animals (liver fat score 1.7+/-1.0 and 0.2+/-0.4; p<0.0001, respectively). CONCLUSIONS: Fed a calorie-rich diet P. obesus develops a syndrome, which shares metabolic, laboratory and histopathologic characteristics compatible with human NAFLD.

Academic stress, immunological reaction, and academic performance among students of nursing and physiotherapy.

The associations among health status, health behavior, and changes in human cytomegalovirus (HCMV) specific salivary antibodies during academic stress were investigated in relation to academic achievement among nursing and physiotherapy students. Fifty-four first year students donated saliva samples and completed a pencil and paper questionnaire before (t1), during two term examinations (t2 and t3), and after grades were posted (t4). An increase in the level of specific salivary HCMV IgG and IgA antibodies from t1 to t2, and a decrease from t2 to t4 were related to academic success. Health status and health behavior remained fairly stable during the stress period. The results are congruent with the inverted U-shape model of stress and learning suggested by Yerkes & Dodson (1908).

Late hemodynamic changes following controlled hemorrhage and volume restitution with blood or Haemaccel in anesthetized portal hypertensive rats.

BACKGROUND AND AIM: In portal hypertensive rats, hemorrhage and acute volume restitution with Haemaccel induced increased cardiac output and portal venous inflow. In the present study, the late hemodynamic effects of this procedure were explored. METHODS: Portal hypertension was induced by portal vein constriction. Blood was withdrawn 11.2 +/- 3.2 days later, at a rate of 0.3 mL/min, for 15 min, followed by 15 min of stabilization. Haemaccel or blood were infused at the same rate and volume used for withdrawal. Hemodynamic measurements were performed after 24 h, using radioactive microspheres. Viscosity was measured with an Ostwald viscometer. Vascular hindrance was calculated as resistance/viscosity ratio. RESULTS: Blood viscosity of the Haemaccel group (n = 11), was lower than in the blood group (n = 11): 2.7 +/- 0.2 versus 4.0 +/- 0.4 (P < 0.01). Arterial pressure, cardiac output, peripheral resistance, portal pressure, portal venous inflow and splanchnic arteriolar resistance were not significantly different. Splanchnic arteriolar and portocollateral hindrance were higher in the Haemaccel group (11.7 +/- 5.3 and 1.5 +/- 0.6 vs 7.7 +/- 3.0 and 0.9 +/- 0.4 mmHg x min x 100 gram body weight/mL, respectively, P < 0.05). CONCLUSION: In portal hypertensive rats, vital organs perfusion, 24 h after hemorrhage and isovolemic volume restitution with Haemaccel and blood, was similar. However, in Haemaccel-transfused animals, a reduction in vascular hindrance, indicating vasoconstriction, was observed in the splanchnic organs, which drain into the portal circulation. Vasoconstriction of the portocollateral vascular bed was observed as well. We suggest that slow-rate volume replacement during a portal-hypertensive-related bleeding episode enables hemodynamic adaptation to occur. Thus, undesirable hyperdynamic changes, which may aggravate secondary bleeding, are attenuated.