This study showed that freeze-thaw processing can eliminate the HTLV-I infectivity of mothers' milk, and that HTLV-I carriers can indirectly feed their infants using frozen-thawed mothers' milk as a way to prevent HTLV-I infection.
We developed a polymerase chain reaction (PCR) method which has high sensitivity and simple technique in order to investigate the presence or absence of human T lymphotropic virus type I (HTLV‐I) provirus in cord blood mononuclear cells of neonates born to HTLV‐I carrier mothers. Out of 40, three subjects were found to contain the HTLV‐I provirus genome. These three subjects remained HTLV‐I sequence‐positive in follow‐up study. On the other hand, when examined by a conventional technique for detection of HTLV‐I‐associated antigen on peripheral mononuclear cells, all 40 neonates were HTLV‐I‐associated antigen‐negative. These results suggest that PCR is more sensitive than the conventional antigen detection method and is useful in early detection of HTLV‐I infection in neonates born to HTLV‐I carriers.
The effect of ristocetin on the platelet surface charge was examined. One part of citrated PRP or platelet suspensions was mixed with nine parts of lOμM Tris-buf f ered saline (pH 7.4) and the mixtures were incubated at 25°C with or without ristocetin. These mixtures were applied for a cell electrophoresis microscope to determine the electrophoretic mobility(EM), from which the platelet surface charge was estimated. A significant reduction in surface negative charge of platelets was observed when ristocetin was added to the mixtures. EM of non-treated and risto-cetin(lmg/ml)-treated platelets was −1.269±0.045 and −0.870±0.040 μ/sec/V/cm, respectively. A dose-response relationship was observed between platelet EM change and ristocetin concentra-tion(0.1~1.2mg/ml). The change in EM reached to the maximum within seconds. Similar reduction of EM was observed when formalin-fixed platelets were incubated with ristocetin. Heparin at concentrations(10u~100u/ml) inhibited, but protamine sulfate(0.05mg/ml) enhanced the change of EM and platelet aggregation by ristocetin. Both the ristocetin-induced aggregation and the reduction of EM were optimally observed at pH 7.3 and were inhibited at pH above 8.0. The presence of plasma component was found to be essential in the reaction mixture for this reduction of EM. EM was decreased in the presence of ristocetin proportionally with the increase in per cent of plasma in the mixture up to 10(v/v)%. The ristocetin-induced reduction in EM of platelets was not observed when normal platelets were suspended in plasma from a patient with Willebrands’ disease(EM= −1.278±0.070 μ/sec/V/cm, with ristocetin, 1mg/ml).These results strongly suggest the involvement of decreased surface negative charge in the mechanism of platelet aggregation induced by ristocetin.
Abstract:Objectives: Human T cell leukemia virus type-I (HTLV-I) is a causative agent of human T-cell leukemia and HTLV-I associated myelopathy (HAM/TSP). HTLV-I carriers are often infected vertically, especially via mother's milk. Since 1985, clinical measures have been adopted at a hospital in Okinawa to prevent vertical infections. Methods: We examined HTLV-I antibodies in all of the women (total 11,506) who gave birth after 24 gestational weeks at a hospital on the Okinawa main island from January 1985 to December 1999. Results: The positive rate among all pregnant women was always higher than that among primipara alone. Both figures decreased over the period studied, but the primiparity rate (36-39%) did not change significantly. The percentage of HTLV-I positive primipara pregnant women among the HTLV-I positive total was close to the primiparity rate from 1985 to 1988, but it was considerably lower than the overall primiparity rate thereafter (22-26%). Conclusions: Preventive measures against HTLV-I infection did not contribute to the decrease in HTLV-I positive mothers before 1999 because these measures were adopted from 1985, and so there must be other reasons for the decrease in HTLV-I positive rate. Further studies on social factors and by year of birth are needed to identify factors influencing HTLV-carrier ratios among pregnant women.
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