Flow-cytometric analysis on cytotoxic effect of thimerosal, a preservative in vaccines, on lymphocytes dissociated from rat thymic glands.

There is a concern on the part of public health community that adverse health consequence by thimerosal, a preservative in vaccines for infants, may occur among infants during immunization schedule. Therefore, the cytotoxic action of thimerosal was examined on lymphocytes dissociated from thymic glands of young rats using a flow cytometer and respective fluorescent probes for monitoring changes in intracellular Ca2+ concentration ([Ca2+]i) and membrane potential, and for discriminating intact living cells, apoptotic living cells and dead cells. Incubation with thimerosal at 3 microM or more (up to 30 microM) for 60 min depolarized the membranes, associated with increasing the [Ca2+]i. Thimerosal at 30 microM induced an apoptotic change in membranes of almost all living cells. Furthermore, the prolonged incubation with 30 microM thimerosal induced a loss of membrane integrity, leading to cell death. Since the blood concentration of thimerosal after receiving vaccines is theoretically submicromolar, it may be unlikely that thimerosal affects lymphocytes of infants.

Property of thimerosal-induced decrease in cellular content of glutathione in rat thymocytes: a flow cytometric study with 5-chloromethylfluorescein diacetate.

There is a concern on the part of public health community that adverse health consequences by thimerosal, a preservative in vaccines for infants, may occur among infants during immunization schedule. Therefore, the effect of thimerosal on cellular content of glutathione was examined on thymocytes obtained from 4-week-old rats using a flow cytometer and 5-chloromethylfluorescein diacetate. Thimerosal at concentrations ranging from 1 to 10 microM reduced the cellular content of glutathione in a concentration-dependent manner, and the complete depletion of cellular glutathione was observed when the cells were treated with 30 microM thimerosal. L-Cysteine significantly attenuated the actions of thimerosal to reduce the glutathione content and to increase the intracellular Ca2+ concentration. Prolonged incubation (24 h) with 1-3 microM thimerosal induced the apoptosis. The cytotoxic action of thimerosal was greatly augmented when the cells suffered oxidative stress induced by H2O2. It may be unlikely that thimerosal exerts potent cytotoxic action under the in vivo condition because the blood concentration of thimerosal after receiving vaccines does not seem to reach micromolar range and nonprotein thiols at micromolar concentrations are present in the blood.

Survey of Florida green turtles for exposure to a disease-associated herpesvirus.

A recently developed enzyme-linked immunosorbent assay (ELISA) was used to assess exposure of Florida wild green turtles Chelonia mydas to LETV, the herpesvirus associated with lung-eye-trachea disease (LETD). Plasma samples from 329 wild juvenile green turtles netted in the Indian River lagoon, along the Sebastian reef, or in the Trident basin (Indian River and Brevard Counties, Florida) were tested by ELISA for the presence of antibodies to LETV. Plasma samples from 180 wild juvenile green turtles were tested from these study sites to compare the prevalence of anti-LETV antibodies. While some plasma samples from each site contained anti-LETV antibodies (confirmed by Western blot analysis), plasma samples collected from the Indian River lagoon had statistically higher optical density values measured in the ELISA. No statistical differences were observed when these same plasma samples were analyzed for changes in the level of anti-LETV antibodies over 3 years (1997, 1998, and 1999). To explore the relationship between anti-LETV antibodies and fibropapillomatosis (FP), plasma from 133 green turtles scored for fibropapilloma tumor severity were tested by ELISA. There was no correlation between tumor severity and the presence of antibodies against LETV. Additional plasma samples collected from 16 tagged green turtles captured and sampled more than once (recaptures) were also tested to monitor antibody levels to LETV relative to the FP status of individual turtles over time. Again there was no clear relationship between FP tumor status and the presence of antibodies to LETV. Finally, ELISA tests on plasma from 13 nesting female turtles (9 green and 4 loggerhead) revealed high levels of anti-LETV antibodies in 11 individuals, including 2 loggerhead turtles. These results provide strong evidence that wild Florida green turtle populations at these 3 study sites are exposed to LETV or a closely related virus and that loggerhead turtles may be exposed as well. Based on a cutoff optical density value of 0.310, 71 out of the 329 wild Florida green turtles tested were seropositive for LETV antibodies (seroprevalence = 21.6%). In addition, no relationship between FP tumor severity or status and the presence of anti-LETV antibodies was found, further supporting the hypothesis that LETV and the FP-associated herpesvirus (FPHV) are separate infections of marine turtles.

Epstein-Barr virus infection resembling autoimmune hepatitis with lactate dehydrogenase and alkaline phosphatase anomaly.

A 73-year-old man had fever, lymphadenopathy, granulocytopenia, thrombocytopenia, ascites, pleural effusion, liver injury, and an allergic-like skin rash. Autoantibodies, such as anti-nuclear antibody, were shown, and there were lactate dehydrogenase and alkaline phosphatase anomalies and platelet-associated IgG. His liver injury resembled that in autoimmune hepatitis. He was diagnosed with Epstein-Barr virus (EBV) infection associated with autoimmunization because of his clinical course, fluctuation of anti EBV antibodies and positive EBV genome in circulating lymphocytes and serum. This case suggests a close relationship between EBV infection and autoimmunization or autoimmune-like hepatitis.

No difference in seroprevalences of Helicobacter pylori infection between patients with pulmonary tuberculosis and those without.

A previous article reported a possible relationship between a history of tuberculosis and Helicobacter pylori infection. Epidemiologic similarities exist between the two infections: Mycobacterium tuberculosis and H. pylori are transmitted from person to person and the risk of acquiring them is elevated in underprivileged environment. This study was conducted to investigate the relationship between the two infections. Serum concentrations of anti-H. pylori IgG antibody were measured in 40 tuberculosis inpatients on antituberculosis chemotherapy for no more than 3 months (group I; 52.4 +/- 21.4 years of age), 43 tuberculosis inpatients on it for more than 3 months (group II; 57.3 +/- 16.3 years), and 60 nontuberculosis outpatients (control subjects; 55.9 +/- 16.7 years). H. pylori seropositivities were similar among control subjects (73.3%), group I (65%), and group II (69.8%). The difference in the antibody concentrations was significant between control subjects and group I (353.7 +/- 321.2 vs. 176.5 +/- 197.9 U/ml) but was not significant between control subjects and group II (353.7 +/- 321.2 vs. 229.9 +/- 249.5 U/ml). The seroprevalences may not be different between patients with pulmonary tuberculosis and those without, and antituberculosis therapy may not decrease the antibody concentrations.

Spontaneous intramural hematoma localized in the proximal esophagus: truly "spontaneous"?

After a usual meal, a 57-year-old woman with normal hemostasis experienced a hematoemesis. She was then diagnosed endoscopically as having an intramural hematoma of the esophagus, which ranged from 18 cm to 24 cm from the incisors. The hematoma is considered to have developed not "spontaneously" but as a result of direct abrasive trauma by foodstuffs. The authors think it appropriate to use the term "spontaneous" only when the development of hematoma is unrelated to emetogenic events, impaired hemostasis, and food-induced injury.

A reliable and convenient parameter of the rate of paracetamol absorption to measure gastric emptying rate of liquids.

The rate of paracetamol absorption represents gastric emptying rate (GER) of liquids. Thus, the liquid GER is assessed by conventional pharmacokinetic parameters such as the maximum concentration and the time to maximum concentration after oral administration of paracetamol. However, the conventional parameters are subject not only to the rate but also to the extent of absorption. For the reliable assessment of GER we have proposed a new parameter, the C0.5/C0.25 ratio, for the rate of paracetamol absorption without being affected by the extent of absorption. Of 15 healthy male volunteers, 9 orally received 10 mg/kg of paracetamol with 200 ml of water as the "normal" GER group, and the other 6 took 10 mg/kg of paracetamol with 200 ml of a liquid nutrient (200 kcal/200 ml), which delays GER, as the "delayed" GER group. Blood samples were obtained at t = 0 (pre-dose), 0.25, 0.5, 0.75, 1.0, 1.5, 2.0, 3.0, 4.0, 6.0, and 8.0 hours (post-dose). In each subject, GER was assessed by the conventional parameters, the C0.5/C0.25 ratio, and the Wagner-Nelson method which provides an accurate estimate of the drug absorption rate. Using the C0.5/C0.25 ratio and the Wagner-Nelson method we could more clearly differentiate the delayed GER group from the normal GER group than by using the conventional parameters. This suggests that the C0.5/C0.25 ratio and the Wagner-Nelson method may be more reliable than the conventional parameters in detecting a delay in GER. Further, it should be noted that the C0.5/C0.25 ratio can be calculated from only 2 blood samples while the Wagner-Nelson method requires repeated blood sampling.

The influence of environmental temperature, thyroid status and a synthetic oestrogen on the induction of fatty livers in chicks.

1. Hepatic lipid content, lipogenic enzyme activity and plasma lipid concentration were measured in chicks reared at 21 degrees or 34 degrees C and after thyroxine (T4), thiouracil (TU), propylthiouracil (PTU), dienestrol diacetate (DD) or PTU with DD had been given for 14 d. 2. At 34 degrees C there was a significant increase in the total liver lipid and triglyceride content. 3. Injections of T4 decreased liver lipid content whereas it was increased by feeding PTU or DD. The effects of PTU were more pronounced at 21 degrees C while those of DD were more pronounced at 34 degrees C. 4. There were significant interactions between temperature, thyroid status and synthetic oestrogen treatments on total lipid and triglyceride content of the liver. Fatty liver with marked steatosis could be produced through synergic actions of PTU and DD in chicks maintained at 21 degrees C.