Bioactivity characterization of 45S5 bioglass using TL, OSL and EPR: Comparison with the case of 58S sol-gel bioactive glass.

The current work exploits the effective application of thermoluminescence (TL), optically stimulated luminescence (OSL) and the possibility of applying Electron Paramagnetic Resonance (EPR) for the discrimination between different bioactive responses in the case of the 45S5 bioactive glass (SiO2 45, Na2O 24.5, CaO 24.5, P2O5 6 in wt%), which was synthesized through melting process. These techniques are suggested mainly due to their low spectroscopic detection thresholds. The original 45S5 in grain size range of 20-40µm was immersed in the Simulated Body Fluid (SBF) for various different immersion times ranging over one week. In this work the 110°C TL peak, a specific OSL component and the EPR signal at g=2.013 ascribed to oxygen hole center (OHC) are used due to their sensitivity to the different bioactive responses. For all luminescence and EPR components, the intensity plot versus immersion time yields sharp discontinuities, resulting in effective probes regarding the timescale for both the beginning as well as the end of the procedure of the crystalline HCAp formation respectively. On the contrary to the smooth decreasing pattern of both luminescence entities, the peak to peak amplitude of the EPR signal indicates an initial increase for the initial 16min of immersion, followed by a further decrease throughout the immersion time duration. The discontinuities monitored for both sensitivity of TL, OSL and EPR, in conjunction with the discontinuities monitored for the sensitization of TL and OSL, when plotted versus immersion time, provide an individual time scale for each one of the chemical reactions involved in the five steps of the aforementioned procedure. According to the authors' best knowledge, scarce characterization techniques could provide this time scale frame, while it is the first time that such an application of OSL and EPR is attempted. Finally, the bioactive response of the 45S5 bioglass was compared with that of the 58S sol-gel bioactive glass, in terms of the timescale of these five stages required for the final formation of the HCAp. The techniques of luminescence and EPR which take advantage of trapped charges are proposed as alternative cheap and prompt effective techniques towards discrimination between different bioactive responses in bioactive glasses.

Hepatitis b surface antigen and alphafetoprotein levels in the serum of healthy women.

Serum alphafetoprotein (AFP) levels were determined by radioimmunoassay in 24 prostitutes and 16 other women positive for hepatitis B surface antigen (HBsAg), but clinically normal. For every positive woman an effort was made to choose 3 HBsAg-negative comparison women, matched for profession (prostitutes or other), age (+/- 2 years), and social class; however, in 5 instances matched triplets (rather than quadruplets) were formed. Among the 40 HBsAg-positive women 9 were AFP positive (23%), whereas among the 115 HBsAg-negative women 13 were AFP positive (11%). A matched analysis indicates that the difference is marginally significant (one-tailed p = 0.03). This finding is compatible with the view that the induction of AFP synthesis in apparently healthy HBsAg-positive individuals may be related with the oncogenic potential of the hepatitis B virus.

Hepatitis B serology in Greek prostitutes: significance of the different serum markers.

One hundred and ninety-eight prostitutes (mean age 41.8 years) and 117 control women of low socio-economic class (mean age 43.8 years) were tested by solid-phase radioimmunoassay for hepatitis B surface antigen (HBsAg), its antibody (anti-HBs) and antibody to hepatitis B core antigen (anti-HBc). The prevalence of HBsAg was higher among prostitutes (11% v. 4%, P approximately 0.06). This difference was accounted for by the higher infection rate of prostitutes to hepatitis B virus (HBV) 97% v. 45%, P less than 10(-6)), since the proportion of HBsAg carriers among those infected was practically the same between the two groups (11% v. 9%). Among the previously infected prostitutes who did not become carriers the majority (75%) were positive for both anti-HBc and anti-HBs, whereas among control women about half (52%) were positive only for anti-HBc.

Viral hepatitis: lack of transmission in an Athenian School.

In the 1975-76 school year, 3 cases of icteric hepatitis occurred almost simultaneously in 2 grades of an Athenian school. An initial survey of the 2 classes approximately one week later found that 88 of 94 children were susceptible to type A hepatitis. No further clinical cases occurred. A second survey at the end of the school year revealed only 2 subclinical hepatitis A virus infections: one coincident with the overt cases in November, and a second from extramural exposure in February. Two carriers of hepatitis B virus in class A were not associated with serologic evidence for communicability of that agent in this setting. Testing of faecal specimens for agents possibly responsible for epidemiological interference with the spread of hepatitis A virus was unsuccessful. Nevertheless, the hypothesis of Band that other agents may interfere with transmission of hepatitis A virus deserves further study.

Prevalence and epidemiologic significance of antibody to hepatitis B core antigen in Greece.

The diagnostic and epidemiologic significance of antibody to hepatitis B core antigen (anti-HBc) detected by complement fixation was studied in a sample of 412 healthy persons, 0-70 years old of both sexes living in the Athens area. The prevalence of hepatitis B virus (HBV) infections was found to be very high (26.5%) and the hepatitis B surface antigen (HBsAg) carrier rate (4.1%) among the highest in Europe. Anti-HBc was detected in 63 (15.3%) of the examined infection. The prevalence of anti-HBc (without HBsAg or anti-HBs) increased with age, while the HBsAg carrier rate declined in older age groups. It was also found that the frequency of anti-HBc persists for a shorter period than the anti-HBs after HBV infection. These data stress the importance of anti-HBc testing in increasing the sensitivity of the detection of potentially infective HBV carriers as well as in studying various epidemiologic aspects of HBV infection.

The effect of intradermal administration of Corynebacterium parvum on the immune response to hepatitis Bs antigen.

The immunopotentiating effect of the intradermal administration of a course of four doses (0.25 ml) of a standard suspension of killed C. parvum (2 mg/ml) was studied in a group of 10 asymptomatic chronic hepatitis B surface antigen (HBsAg) carriers, as well as in 11 persons with antibodies to HBsAg (anti-HBs) and six without HBsAg or anti-HBs. HBsAg, anti-HBs, and leukocyte migration inhibition (LMI) studies were performed in pre- and post-inoculation blood samples. C. parvum produced a substantial increase of anti-HBs titre in persons with preexisting anti-HBs. However, anti-HBs responses were not induced in carriers. HBsAg was not eliminated and its titre remained practically unchanged in carriers. These results support the hypothesis that in carriers the specific defect in the immune response to HBsAg possibly exists at the B cell level.

Seroepidemiological study of HBV infections in Athens, Greece.

A seroepidemiological survey of a sample-roughly representative by age and sex - of 2744 persons of the Greater Athens area revealed that hepatitis B virus (HBV) infections are highly endemic in Greece. Hepatitis B surface antigen (HBsAg) was detected in 72(2-6%) of them. The subtype was identified in 70 of the 72 carriers, and 69 were ay; the other was ad. Determinant w was present in all 61 that were capable of being typed further, and a23y(w) was twice as common as a11y(w). Antibody to HBsAg (anti-HBs) was found in 514 (18-7%) persons. The prevalence of the HBsAg rose rapidly with age, reaching peak values (5-3%) at 20-29 years, while anti-HBs reached its highest value (42-1%) in older age groups (50-59 years). The frequency of HBsAg was significantly higher in males (3-4%) than in females (1-5%). The percentage of infected persons who become chronic HBsAg carriers (12-3%) was found higher than in other developed populations. It was also found higher in children (25%) than in adults (5-5%) and in males (14-6%) than in females (8-1%). These data indicate that HBV infection in early life is a major risk factor in the development of HBsAg carriers and support the hypothesis that males are more likely to become HBsAg carriers than females.