Poplar for the phytomanagement of boron contaminated sites.

Boron (B) is a widespread environmental contaminant that is mobile relative to other trace elements. We investigated the potential of hybrid poplar (Populus sp.) for B phytomanagement using a lysimeter experiment and a field trial on B-contaminated wood-waste. In both studies, poplars enhanced evapotranspiration from the wood-waste, reduced B leaching, and accumulated B in the aerial portions of the tree. When grown in a substrate containing 30 mg/kg B, poplar leaves had an average B concentration of 845 mg/kg, while the stems contained 21 mg/kg B. Leaf B concentrations increased linearly with leaf age. A decomposition experiment revealed that abscised leaves released 14% of their B during the winter months. Fertiliser application enhanced tree growth without decreasing the leaf B concentrations. Harvesting alternate rows of trees on a contaminated site would reduce leaching from the site while removing B. Harvested plant material may provide bioenergy, stock fodder, or an amendment for B-deficient soils.

Serological, epidemiological, and molecular differences between human T-cell lymphotropic virus Type 1 (HTLV-1)-seropositive healthy carriers and persons with HTLV-I Gag indeterminate Western blot patterns from the Caribbean.

To investigate the significance of serological human T-cell lymphotropic virus type 1 (HLTV-1) Gag indeterminate Western blot (WB) patterns in the Caribbean, a 6-year (1993 to 1998) cross-sectional study was conducted with 37,724 blood donors from Guadeloupe (French West Indies), whose sera were routinely screened by enzyme immunoassay (EIA) for the presence of HTLV-1 and -2 antibodies. By using stringent WB criteria, 77 donors (0.20%) were confirmed HTLV-1 seropositive, whereas 150 (0.40%; P < 0.001) were considered HTLV seroindeterminate. Among them, 41.3% (62) exhibited a typical HTLV-1 Gag indeterminate profile (HGIP). Furthermore 76 (50.7%) out of the 150 HTLV-seroindeterminate subjects were sequentially retested, with a mean duration of follow-up of 18.3 months (range, 1 to 70 months). Of these, 55 (72.4%) were still EIA positive and maintained the same WB profile whereas the others became EIA negative. This follow-up survey included 33 persons with an HGIP. Twenty-three of them (69.7%) had profiles that did not evolve over time. Moreover, no case of HTLV-1 seroconversion could be documented over time by studying such sequential samples. HTLV-1 seroprevalence was characterized by an age-dependent curve, a uniform excess in females, a significant relation with hepatitis B core (HBc) antibodies, and a microcluster distribution along the Atlantic coast of Guadeloupe. In contrast, the persons with an HGIP were significantly younger, had a 1:1 sex ratio, did not present any association with HBc antibodies, and were not clustered along the Atlantic façade. These divergent epidemiological features, together with discordant serological screening test results for subjects with HGIP and with the lack of HTLV-1 proviral sequences detected by PCR in their peripheral blood mononuclear cell DNA, strongly suggest that an HGIP does not reflect true HTLV-1 infection. In regard to these data, healthy blood donors with HGIP should be reassured that they are unlikely to be infected with HTLV-1 or HTLV-2.

Human T cell leukemia virus Type I (HTLV-I) infection induces greater expansions of CD8 T lymphocytes in persons with HTLV-I-associated myelopathy/tropical spastic paraparesis than in asymptomatic carriers.

A quantitative study of the T cell receptor repertoire was performed ex vivo on CD4 and CD8 T cell subsets of human T cell leukemia virus type I (HTLV-I)-infected asymptomatic carriers and patients with HTLV-I-associated myelopathy/tropical spastic paraparesis (HAM/TSP). Indexes of oligoclonality that compiled all repertoire modifications were calculated for peripheral blood mononuclear cells and for CD4 and CD8 T cell subsets. Both patients with HAM/TSP and asymptomatic carriers had greater T lymphocyte expansions than did uninfected donors, which was independent of age and at least twice higher in the CD8 than in the CD4 cell compartment. Some expanded CD8 T cells corresponded to cytotoxic T lymphocytes directed against various epitopes of the immunodominant Tax protein. Patients with HAM/TSP had significantly higher CD8 cell expansions than did asymptomatic carriers. These results highlight the prognostic value of measuring CD8 T cell expansions during follow-up of HTLV-I infection.

Evidence for the chronic in vivo production of human T cell leukemia virus type I Rof and Tof proteins from cytotoxic T lymphocytes directed against viral peptides.

Human T cell leukemia virus type I (HTLV-I) is a persistent virus that causes adult T cell leukemia and tropical spastic paraparesis/HTLV-I-associated myelopathy. Studies on rabbits have shown that viral proteins encoded by the open reading frames pX-I and pX-II are required for the establishment of the persistent infection. To examine the in vivo production of these proteins in humans, we have investigated whether cytotoxic T lymphocytes isolated from HTLV-I-infected individuals recognized pX-I and pX-II peptides. CD8(+) T lymphocytes to pX-I and pX-II peptides were detected in HTLV-I-infected individuals, whatever their clinical status, and even in the absence of any antigenic restimulation. These findings indicate that the HTLV-I pX-I and pX-II proteins are chronically synthesized in vivo, and are targets of the natural immune response to the virus.

Human T-lymphotropic virus type I among blood donors from Guadeloupe: donation, demographic, and biologic characteristics.

BACKGROUND: Epidemiologic data on human T-lymphotropic virus type I (HTLV-I) in Guadeloupe (French West Indies) are scant. STUDY DESIGN AND METHODS: From January 1989 to December 1996, 59,426 blood donors were screened by enzyme immunoassay for antibodies to HTLV-I. All repeatedly reactive samples were confirmed by Western blot. Temporal trends in HTLV-I seropositivity rates were examined during the study period. A multivariate analysis of donation, demographic, and biologic characteristics was performed. RESULTS: Of the screened blood donors, 195 were confirmed as seropositive, for an overall prevalence of 0.33 percent (95% CI 0.28-0.38). A marked decrease in overall HTLV-I prevalence with time (from 0.47% in 1989 to 0.13% in 1996) was observed, which can be explained mainly by the decreasing percentage of recruited new donors during the study period. Four independent risk factors for HTLV-I were identified: new donor status (odds ratio [OR] 12.5), female sex (OR 1.7), increasing age (30-39 years: OR, 2.4; 40-49 years: OR, 3.7; >50 years: OR 6.6), and positive antibodies to hepatitis B virus core antigen (OR, 1.7). Selection of specific locations for blood collection was inversely associated with HTLV-I (OR 0.5). CONCLUSION: New donor status, advancing age, female sex, and positivity for hepatitis B virus core antibodies were the major factors associated with HTLV-I infection in Guadeloupe.

Geographical clustering of human T-cell lymphotropic virus type I in Guadeloupe, an endemic Caribbean area.

Between January 1989 and December 1996, 59,426 blood donors from Guadeloupe (French West Indies) were screened for antibodies to human T-cell lymphotropic virus type I (HTLV-I). Of these, 195 were confirmed as being positive for HTLV-I, yielding an overall prevalence of 0.33% [95% confidence interval (CI) 0.28-0.38]. On multiple logistic regression analysis, risk factors for HTLV-I were female gender [odds ratio (OR) 1.8; CI 1.3-2.4], increasing age (30-39 years, OR 2.2, CI 1.4-3.4; 40-49 years, OR 3.1, CI 2.1-4.7; > or =50 years, OR 5.6, CI 3.6-8.6) and positive hepatitis B core antibodies (OR 2.0; CI 1.5-2.8). HTLV-I seropositivity was also significantly associated with current residence in certain areas, highlighting microgeographic clustering: individuals living along the Atlantic Facade of Guadeloupe, which is a traditional sugar cane plantation area where Africans were brought during slave trading, were at increased risk for HTLV-I infection (OR 1.9; CI 1.3-2.7) compared with other areas in Guadeloupe devoted to other activities. Our report of HTLV-I cluster identification in Guadeloupe probably reflects both its low spread and its highly intrafamilial restricted transmission within this endemic Caribbean population.

[Carriage of HBs antigen and infection by delta agent in Cameroon]. / Portage de l'antigène HBs et infection par l'agent delta au Cameroun.

Serum samples taken from 370 healthy individuals (aged 15-44) constituting a randomized sample representative of the adult population of the town of Nkongsamba, Cameroon, were tested for Hepatitis B virus surface antigen (HBs); positive samples were then tested for Hepatitis B virus [e] antigen (HBe) and anti-Delta antibody. The mean carrier rate of HBs was 8.4% +/- 2.8%; within HBs carriers, 29% exhibited HBe and 6.5% anti-Delta antibody.