HIV-1-specific immune responses in subjects who temporarily contain virus replication after discontinuation of highly active antiretroviral therapy.

Therapeutic intervention with highly active antiretroviral therapy (HAART) can lead to suppression of HIV-1 plasma viremia to undetectable levels for 3 or more years. However, adherence to complex drug regimens can prove problematic, and subjects may temporarily discontinue HAART for variable periods. We studied 6 HIV-1-infected individuals who stopped therapy. Off HAART, levels of viremia were suppressed to fewer than 500 copies/mL in 2 subjects for more than 12 and more than 24 months, respectively, and in 1 subject for 4 months on 1 occasion. Three subjects failed to contain plasma viremia. Broad and strong HIV-1-specific immune responses were detected in subjects with prolonged suppression of viral replication. This longitudinal study suggests that containment of HIV-1 replication to low or undetectable levels after discontinuation of HAART is associated with strong virus-specific immune responses. Boosting of HIV-1-specific immune responses should be considered as an adjunctive treatment strategy for HIV-1-infected individuals on HAART.

Characterisation of the biosand filter for E. coli reductions from household drinking water under controlled laboratory and field use conditions.

More than a billion people in the developing world lack access to safe and reliable sources of drinking water. Point of use (POU) household water treatment technology allows people to improve the quality of their water by treating it in the home. One emerging POU technology is the biosand filter (BSF), a household-scale, intermittently operated slow sand filter. Laboratory and field studies examined Escherichia coli reductions achieved by the BSF. During two laboratory studies, mean E. coli reductions were 94% and they improved over the period of filter use, reaching a maximum of 99%. Field analysis conducted on 55 household filters near Bonao, Dominican Republic averaged E. coli reductions of 93%. E. coli reductions by the BSF in laboratory and field studies were less than those typically observed for traditional slow sand filters (SSFs), although as for SSFs microbial reductions improved over the period of filter use. Further study is needed to determine the factors contributing to microbial reductions in BSFs and why reductions are lower than those of conventional SSFs.

Risks and benefits of structured antiretroviral drug therapy interruptions in HIV-1 infection.

BACKGROUND: Structured interruptions of antiretroviral therapy of HIV-1 infected individuals are currently being tested in clinical trials to study the effect interruptions have on the immune responses and control of virus replication. OBJECTIVE: To investigate the potential risks and benefits of interrupted therapy using standard population dynamical models of HIV replication kinetics. METHODS: Standard population dynamical models were used to study the effect of structured therapy interruptions on the immune effector cells, the latent cell compartment and the emergence of drug resistance. CONCLUSIONS: The models suggest that structured therapy interruption only leads to transient or sustained virus control if the immune effector cells increase during therapy. This increase must more than counterbalance the increase in susceptible target cells induced by therapy. The risk of inducing drug resistance by therapy interruptions or the risk of repopulating the pool of latent cells during drug-free periods may be small if the virus population remains at levels considerably below baseline. However, if the virus load increases during drug-free periods to levels similar to or higher than baseline before therapy, both these risks increase dramatically.

The virological and immunological consequences of structured treatment interruptions in chronic HIV-1 infection.

BACKGROUND: Some individuals with chronic HIV-1 infection have discontinued their drug therapy with consequent plasma virus rebound. In a small number of patients, a delayed or absent rebound in plasma virus load has been noted after drug cessation, apparently associated with prior drug interruptions and autologous boosting of HIV-1 specific immune responses. We hypothesized that cyclic structured treatment interruptions structured treatment interruptions (STI) could augment HIV-1 specific immune responses in chronic HIV-1 infection, which might help to control HIV-1 replication off therapy. METHODS: We initiated an STI pilot study in 10 antiretroviral treatment-naive HIV-1 chronically infected subjects with baseline CD4 T-cell counts > 500 x 10(6) cells/l and plasma viral load > 5000 copies/ml who received highly active antiretroviral therapy (HAART) for 1 year with good response (plasma viral load < 20 copies/ml for at least 32 weeks). Three cycles of HAART interruption were performed. RESULTS: In all of the patients viral load rebounded, but doubling times increased significantly between the first and third stops (P = 0.008), and by the third stop, six out of nine subjects had a virological set-point after a median 12 months off therapy that was lower than baseline before starting HAART (ranging from 0.6 log(10) to 1.3 log(10) lower than baseline) and in four it remained stable below 5000 copies/ml. Those subjects who controlled viral replication developed significantly stronger HIV-1 specific cellular immune responses than subjects lacking spontaneous decline (P < 0.05). During viral rebounds no genotypic or phenotypic changes conferring resistance to reverse trancriptase inhibitors or protease inhibitors was detected, but mean absolute CD4 T-cell counts declined significantly, although never below 450 x 10(6)/l and the mean value at 12 months off therapy was significantly higher than the pre-treatment level (P = 0.004). CONCLUSIONS: Our findings suggest that STI in chronic HIV-1 infection might augment HIV-1-specific cellular immune responses associated with a spontaneous and sustained drop in plasma viral load in some subjects but at the potential cost of lower CD4 T-cell counts.

Palatal changes associated with reverse smoking in Filipino women.

OBJECTIVE: To determine baseline data for the presence or absence of reverse-smoking and conventional smoking associated oral palatal mucosal changes in women. DESIGN: A cross-sectional evaluation of the clinical and cytological changes associated with the condition. SETTING: Nine rural barangays in Cabanatuan City, Philippines. SUBJECTS AND METHODS: Nine-one volunteer women smokers (61 reverse and 30 conventional) were examined clinically and photographically. Smears were also taken from three areas and the palate to investigate the cytology of palatal mucosal epithelium. MAIN OUTCOME MEASURES: Variations in colour, texture and topography of the palatal mucosa; determination of epithelial cell characteristics and inflammatory cell populations present in the lesions. RESULTS: Clinical findings showed that subjects could be grouped into three categories: Group A subjects showed pigmentation and some erythema only; Group B subjects included those with ulceration, marked erythema and non-descript mucosal roughening; Group C subjects (comprising the majority of reverse smokers) exhibited various combination of leukoplakia, fissuring, thickening and pigmentation of the palatal mucosa. Additional features, including nodularity, erythema, prominence and reddening of minor salivary gland duct openings were also occasionally observed in this group. Cytologic analysis revealed that, within each smoking group, there was a significant site-dependent difference in the predominant epithelial cell type present. CONCLUSIONS: This study reports the first systematic description of reverse smoking associated palatal mucosal changes in Filipino women. It also provides a basis for classification of the palatal mucosal changes among reverse smokers.

The relationship between T cell proliferative responses and plasma viremia during treatment of human immunodeficiency virus type 1 infection with combination antiretroviral therapy.

The relationship between human immunodeficiency virus (HIV) type 1 replication and CD4+ T cell function was examined. T lymphocyte proliferation in response to both HIV-1 antigens and recall antigens was measured in HIV-1-infected individuals before and after they received highly active antiretroviral therapy (HAART). No correlation was observed between baseline viral load or CD4+ T cell count and the T cell proliferative response to HIV-1 Gag. Suppression of viremia was not associated with an increase in T cell proliferative responses. Emergence of viral replication during short periods of intermittent therapy promoted generalized activation of T helper lymphocytes, manifested by increased T cell proliferative responses to HIV-1 Gag and recall antigens. Recovery of CD4+ T cell responses occurred in some individuals who initiated HAART years after infection and who were intermittently adherent to drug treatment. Thus, CD4+ T cell responses can sometimes be regenerated if viral load is suppressed to allow some immune recovery and if antigenic stimulation is later provided.

Partial purification and characterization of the interconvertible forms of trehalase from Saccharomyces cerevisiae.

Cryptic trehalase from Saccharomyces cerevisiae was purified about 3000-fold. The recovery of 970% of the original "activity" indicated the removal of an inhibitor of the enzyme. Active trehalase, obtained through phosphorylation of cryptic trehalase by cAMP-dependent protein kinase, was isolated by chromatography on DEAE-cellulose. A major phosphorylated protein, with an apparent Mr of 86,000, was detected after SDS-polyacrylamide gel electrophoresis. This protein band correlated exactly with the elution profile of trehalase activity and 32Pi incorporation into the enzyme on DEAE-cellulose chromatography. Partially purified active trehalase showed absolute specificity towards trehalose with an apparent Km of 4.79 X 10(-3) M. Both forms of the enzyme showed an apparent molecular weight of 160,000, by gel filtration. Centrifugation on a glycerol density gradient indicated multiple forms of trehalase-c, with Mr of 320,000, 160,000, and 80,000. After activation of each of these forms by protein kinase, a single form of trehalase-a was observed, with a Mr of 160,000. Trehalase-c appears to be a totally inactive form of the enzyme. The only mechanism of activation seems to be phosphorylation by cAMP-dependent protein kinase. When the protein kinase concentration was varied, at a fixed trehalase-c concentration, a sigmoidal activation plot was obtained. This result suggests the occurrence of multiple forms of cryptic trehalase.

Activity and stability of a Rhizomucor miehei lipase in hydrophobic media.

The effects of detergents and organic solvents on a commercial lipase (Lipozyme) from Rhizomucor miehei were investigated. It was shown that the detergent sodium cholate is possibly an activator of the enzyme, increasing lipase activity 2.5 times (250% of the control) when the enzyme was preincubated with 7 mM cholate. Lipozyme activity was over twice as high (230% of the control) in the presence of 80 mM Tween 80 or 90 mM Tween 20 (polyoxyethylenesorbitan monolaurate), apparently through an additional emulsifying action on the substrate. Preincubation with Tween 80 (polyoxyethylenesorbitan mono-oleate) did not affect enzyme activity. In contrast, lipase activity was completely inhibited in the presence of an 8.9 mM concentration of another non-ionic detergent, Brij 58, whereas with a 16.4 mM concentration of the cationic detergent cetyltrimethylammonium bromide (CTAB), enzyme activity was reduced by 80%. Preincubation of Lipozyme with the same concentrations of Brij 58 [poly(oxyethylene)20 cetyl ether] and CTAB promoted total inactivation of the enzyme. Organic solvents had different effects on lipase activity and stability. Of the tested solvents, hexane was least deleterious to lipase activity and did not alter enzyme stability on preincubation. These results suggest that Lipozyme can be used in esterification reactions with hexane as solvent or in hydrolysis reactions with Tween 20 or Tween 80 as emulsifying agents, after pretreatment with sodium cholate.

Structured antiretroviral treatment interruptions in chronically HIV-1-infected subjects.

The risks and benefits of structured treatment interruption (STI) in HIV-1-infected subjects are not fully understood. A pilot study was performed to compare STI with continuous highly active antiretroviral therapy (HAART) in chronic HIV-1-infected subjects with HIV-1 plasma RNA levels (VL) <400 copies per ml and CD4(+) T cells >400 per microl. CD4(+) T cells, VL, HIV-1-specific neutralizing antibodies, and IFN-gamma-producing HIV-1-specific CD8(+) and CD4(+) T cells were measured in all subjects. STIs of 1-month duration separated by 1 month of HAART, before a final 3-month STI, resulted in augmented CD8(+) T cell responses in all eight STI subjects (P = 0.003), maintained while on HAART up to 22 weeks after STI, and augmented neutralization titers to autologous HIV-1 isolate in one of eight subjects. However, significant decline of CD4(+) T cell count from pre-STI level, and VL rebound to pre-HAART baseline, occurred during STI (P = 0.001 and 0.34, respectively). CD4(+) T cell counts were regained on return to HAART. Control subjects (n = 4) maintained VL <400 copies per ml and stable CD4(+) T cell counts, and showed no enhancement of antiviral CD8(+) T cell responses. Despite increases in antiviral immunity, no control of VL was observed. Future studies of STI should proceed with caution.

Enhancement of human immunodeficiency virus type 1-specific CD4 and CD8 T cell responses in chronically infected persons after temporary treatment interruption.

Immunologic and virologic outcomes of treatment interruption were compared for 5 chronically human immunodeficiency virus (HIV)-infected persons who have maintained antiretroviral therapy-mediated virus suppression, as compared with 5 untreated controls. After a median interruption of 55 days of therapy accompanied by rebound of virus, reinitiated therapy in 4 of 5 subjects resulted in suppression of 98.86% of plasma virus load by 21-33 days and no significant decrease in CD4 T cell percentage from baseline. Increased T helper responses against HIV-1 p24 antigen (P=. 014) and interferon-gamma-secreting CD8 T cell responses against HIV-1 Env (P=.004) were present during interruption of therapy and after reinitiation of treatment. The remaining subject whose treatment was interrupted did not resume treatment and continued to have a low virus load (<1080 HIV-1 RNA copies/mL) and persistent antiviral cell-mediated responses. In summary, cellular immunity against autologous HIV-1 has the potential to be acutely augmented in association with temporary treatment interruption in chronically infected persons.

Avaliação fototóxica e screening mutagênico de extratos de propolis, Aloe spp. e Hamamelis virginiana / Evaluation of phototoxic and mutagenic activity of propolis, Aloe spp. and Hamamelis virginiana extracts

A utilização de extratos vegetais em produtos farmacêuticos e cosméticos tem mostrado ser uma tendência mundial e cresceu substancialmente nas duas últimas décadas. No entanto, há ainda poucos relatos na literatura com relação à atividade mutagênica ou fototóxica de extratos vegetais. No presente trabalho foi avaliada a atividade fototóxica e o screening mutagênico de extratos fuidos e secos de própolis, Aloe spp. e Hamamelis virginiana. Na investigação de fototoxicidade foram realizados ensaios microbiológicos, utilizando cepas de Candida albicans e Saccharomyces cerevisiae, bem como ensaios biológicos com cobaias albinos. Extratos etanólicos de Ruta graveolens e Citrus spp., além de 8-metoxipsoraleno (fármaco sintético padrão), foram usados como controles positivos de ambos os testes. A atividade mutagênica foi avaliada qualitativamente segundo o spot test descrito por Maron & Ames, com cepas de Salmonella typhimurium TA97, TA98, TA100 e TA102, empregando como controle positivo o óxido de 4-nitroquinolina. Não foi observada atividade fototóxica, em ambos os ensaios realizados, para qualquer dos extratos. O ensaio microbiológico demonstrou uma atividade fungistática ou fungicida nos extratos secos de hamamélis. Os resultados obtidos nos ensaios microbiológicos com a levedura S. cerevisiae indicam que este microrganismo apresentou eficiência no procedimento de screening de atividade fototóxica comparável à obtida com C. albicans. Os extratos vegetais não apresentaram atividade mutagênica nos ensaios preliminares realizados

Atividade fotoprotetora e estudos preliminares de fotodegradação dos extratos de Aloe spp. e Hamamelis virginiana / Photoprotective activity and prliminary studies on photodegradation of Aloe spp. and Hamamelis virginiana extracts

A radiação solar, especialmente a ultravioleta, é reconhecida como a principal responsável pelo aumento da incidência de câncer em grande parte do mundo, inclusive no Brasil. A busca de substâncias com potencial ação fotoprotetora é uma importante ferramenta no combate a esta neoplasia. O objetivo deste trabalho é avaliar a ação dos extratos vegetais de Aloe spp. e H. virginiana como filtro solar, assim como da associação destes extratos ao filtro sintético p-metoxicinamato de 2-etilhexila. Estudos preliminares de fotodegradação destes extratos, frente à radiação visível e UVB, também foram realizados. Os extratos foram obtidos por extração em forno de microondas e concentrados a extratos fluidos e secos. O fator de proteção solar (FPS) de soluções contendo 3 e 10 por cento (p/V) dos extratos foi determinado por método espectrofotométrico in vitro. Os extratos secos apresentaram valores de FPS maiores que os extratos fluidos. A associação destes extratos ao filtro sintético resultou em aumento nos valores de FPS, sugerindo um efeito sinérgico. Nos estudos de fotodegradação foi observado que o extrato de hamamélis não sofreu alteração no perfil de absorção, após exposição à radiação visível e a UVB. No extrato de Aloe, no entanto, foram observadas alterações no perfil de absorção, quando incidido pelas duas radiações, mas somente a exposição à radiação UVB levou à diminuição de 2 unidades no FPS.