RESUMO
In estimating the crew exposures during an extra vehicular activity (EVA), the contribution of reentrant electrons has always been neglected. Although the flux of these electrons is small compared to the flux of trapped electrons, their energy spectrum extends to several GeV compared to about 7 MeV for trapped electrons. This is also true of splash electrons. Using the measured reentrant electron energy spectra, it is shown that the dose contribution of these electrons to the blood forming organs (BFO) is more that 10 times greater than that from the trapped electrons. The calculations also show that the dose-depth response is a very slowly changing function of depth, and thus adding reasonable amounts of additional shielding would not significantly lower the dose to BFO.
Assuntos
Elétrons , Atividade Extraespaçonave , Sistema Hematopoético/efeitos da radiação , Proteção Radiológica , Voo Espacial , Medicina Aeroespacial , Astronautas , Radiação Cósmica , Meio Ambiente Extraterreno , Olho/efeitos da radiação , Humanos , Fótons , Doses de Radiação , Monitoramento de Radiação , Pele/efeitos da radiação , Trajes EspaciaisRESUMO
A trial of a modified reverse passive haemagglutination test for HBsAg using a 0.1% cell suspension instead of the recommended 1% showed an approximately eight-fold increase in detection sensitivity. The test can be performed within 30 minutes and lends itself to mass screening techniques. Confirmation tests can be done using the 0.1% method. In addition, the same serological plates and cells used for HBsAg screening can then be used to screen for high-titre anti-HBs. This makes the overall screening for both HBsAg and high-titre anti-HBs donors cheap and convenient.
Assuntos
Anticorpos Antivirais/análise , Doadores de Sangue , Testes de Hemaglutinação , Anticorpos Anti-Hepatite B/análise , Antígenos de Superfície da Hepatite B/análise , Reações Falso-Positivas , Hepatite B/imunologia , Humanos , RadioimunoensaioRESUMO
Fifty-two British-born blood donors who were chronic carriers of hepatitis B surface antigen (HBsAg) were tested for the presence of hepatitis B e antigen (HBeAg) and antibody to HBeAg by an immunoradiometric assay. The presence of HBeAg was closely associated with a slight rise in serum liver enzyme concentrations, a high HBsAg titre, and male sex. We suggest that the finding of persistently raised serum liver enzyme concentrations in an asymptomatic HBsAg carrier might be useful as a likely indicator of HBeAg and high infectivity.
Assuntos
Portador Sadio/enzimologia , Hepatite B/transmissão , Fígado/enzimologia , Portador Sadio/imunologia , Feminino , Hepatite B/enzimologia , Hepatite B/imunologia , Anticorpos Anti-Hepatite B/análise , Antígenos da Hepatite B/análise , Antígenos de Superfície da Hepatite B/análise , Humanos , Masculino , Fatores SexuaisAssuntos
Doadores de Sangue , gama-Glutamiltransferase/sangue , Adolescente , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Valores de ReferênciaRESUMO
In a retrospective comparison between countermigration immunoelectrophoresis (CIEP) and reverse passive haemagglutination (RPHA) for screening 260,500 blood donations, the latter's 10-fold increase in sensitivity resulted in 36% more HBsAg detections. In a prospective comparison between RPHA and radioimmunoassay (RIA) the latter's 40-fold increase in sensitivity over RPHA resulted in 11% more detections than RPHA in 27,094 new donors. One in 500 new donors was HBsAg-positive by RPHA, compared with 1 in 11,000 established donors who had donated and been tested previously. Acute hepatitis B infections, though uncommon, accounted for a greater proportion of the HBsAg-positive found in "established" rather than new donors. Reported post-transfusion hepatitis cases have declined following the introduction of screening tests in 1971. The feasibility of RIA testing at a transfusion centre supplied simply with the two basic RIA reagents has been demonstrated.
