Modeling reflection loss from an evacuated tube inside a compound parabolic concentrator with a cylindrical receiver.

Linear compound parabolic concentrators with cylindrical receivers are often combined with evacuated tubes along their focal length to suppress convective heat loss for use as thermal collectors. When investigating the optical efficiency of such collectors it is important to consider the reflection loss introduced by the evacuated tube particularly at large angles of incidence of light onto the CPC aperture. In this paper reflection losses are determined using ray-tracing as a function of the angle of incidence in both the longitudinal and transversal planes of a CPC. The reflection losses are found to be approximately constant except close to the maximum acceptance angle.

Incidence of human herpes virus-6 and human cytomegalovirus infections in donated bone marrow and umbilical cord blood hematopoietic stem cells.

This study examined the incidence of human herpes virus-6 (HHV-6) and human cytomegalovirus (HCMV) infections that are potentially transmitted to haematopoietic stem cells (HSC) transplant recipients via bone marrow (BM) or umbilical cord blood (UCB). Bone marrow progenitor cells were collected from 30 allogenic BM donors. UCB HSC were collected from 34 subjects. The extracted DNA was then processed using nested polymerase chain reaction (nPCR) technique. HCMV and HHV-6 serological status were determined by enzyme immunoassay (EIA). Nested PCR identified HCMV in 22 (73%) of 30 samples of BM progenitor cells but in only eight (23.5%) of 34 samples of UBC HSC ( P = 0.001). HHV-6 DNA was detected in 11 (36.6%) of 30 BM progenitor cells and in only one (2.9%) of 34 UBC cells ( P = 0.002). Both HHV-6 and HCMV infections were determined in nine (26.5%) of 34 bone marrow samples. The results indicate that, the risk of HCMV and HHV-6 via BM progenitor cells is higher than transmission by UCB cells ( P= 0.04).

Outcome of hepatitis B and C virus infection on graft function after renal transplantation.

INTRODUCTION: Chronic liver disease resulting from hepatitis B virus (HBV) and hepatitis C virus (HCV) infections is still a major concern in kidney recipients. It is unclear whether HCV antibody status and markers of HBV infection are associated with renal dysfunction. Thus, we designed a study to investigate the incidence of HBV and HCV infection after renal transplantation and whether these infections alter graft function. METHODS: Fifty-eight patients who underwent renal transplantation participated in the study. Serum creatinine and aminotransferase levels were measured with standard automated analyzers. Anti-HCV antibodies were detected with an enzyme immunoassay, and a reverse transcriptase-polymerase chain reaction (RT-PCR) technique was used to test for HCV-RNA. Serological markers for HBV (HBsAg and anti-HBc antibody) were detected by enzyme immunoassay. All samples from patients who were seropositive for HBsAg or anti-HBc antibody were PCR-tested for HBV-DNA. A serum sample collected from living donors was tested for anti-HCV antibodies and serological markers for HBV. Serum creatinine and aminotransferase levels were also measured in living donors. RESULTS: Anti-HCV was not detected in serum samples of any cases before transplantation. However, 10 (17.2%) tested positive after transplantation. HCV-RNA was detected in 2 of the 10 patients (3.4% of all patients). None of the pretransplantation serum samples tested positive for HBsAg. However, anti-HBc antibody was identified in 8 (13.8%) of the 58 patients.. No HBV DNA was detected in serum samples of the patients with anti-HBc or HBsAg-positive. HBsAg was only detected in 1 (1.7%) recipient after transplantation. None of the 58 patients showed clinical signs or symptoms of renal dysfunction during the study period. CONCLUSION: Our data suggest that, neither HBV nor HCV infection appears to cause or contribute to renal dysfunction in the early period (1 year) after renal transplantation. Nevertheless, a long-term consequence of chronic HBV or HCV liver disease or graft loss is not impossible in renal transplant recipients.

Risk of viral transmission via bone marrow progenitor cells versus umbilical cord blood hematopoietic stem cells in bone marrow transplantation.

Hematopoietic stem cell transplantation (HSCT) is the treatment of choice for children and certain adults with malignant and nonmalignant hematologic disease. Since viral infections are the major problem, this study examined those that might potentially be transmitted to HSCT recipients via bone marrow (BM) versus umbilical cord blood (UCB). BM progenitor cells, peripheral blood leukocytes, and plasma samples were collected from 30 allogenic BM donors. Umbilical cord blood hematopoietic stem cells and plasma samples were also collected from 34 UCB donors. Viral DNA extracted and purified from collected specimens was processed using nested polymerase chain reactions (PCR) to detect human parvovirus B19 (HPV B19), human herpesvirus-6 (HHV-6), varicella-zoster virus (VZV), human cytomegalovirus (HCMV), and Epstein-Barr virus (EBV). The prevalences of HCMV DNA in collected BM progenitor cells versus UCB hematopoietic stem cells were 73% versus 23%, respectively. Conversely, HHV-6 DNA was not detected in any collected specimen by simple PCR. Distribution of the other investigated virus DNAs except EBV DNA was similar in specimens collected from both groups. EBV DNA was not determined in UCB hematopoietic stem cells. The results indicate that the risk of viral transmission to BM transplant recipients via UCB hematopoietic stem cells is less than that with BM progenitor cells.