Randomized trial of benznidazole for chronic Chagas' cardiomyopathy

BACKGROUND:The role of trypanocidal therapy in patients with established Chagas' cardiomyopathy is unproven.METHODS:We conducted a prospective, multicenter, randomized study involving 2854 patients with Chagas' cardiomyopathy who received benznidazole or placebo for up to 80 days and were followed for a mean of 5.4 years. The primary outcome in the time-to-event analysis was the first event of any of the components of the composite outcome of death, resuscitated cardiac arrest, sustained ventricular tachycardia, insertion of a pacemaker or implantable cardioverter-defibrillator, cardiac transplantation, new heart failure, stroke, or other thromboembolic event.RESULTS:The primary outcome occurred in 394 patients (27.5%) in the benznidazole group and in 414 (29.1%) in the placebo group (hazard ratio, 0.93; 95% confidence interval [CI], 0.81 to 1.07; P=0.31). At baseline, a polymerase-chain-reaction (PCR) assay was performed on blood samples obtained from 1896 patients; 60.5% had positive results for Trypanosoma cruzi on PCR. The rates of conversion to negative PCR results (PCR conversion) were 66.2% in the benznidazole group and 33.5% in the placebo group at the end of treatment, 55.4% and 35.3%, respectively, at 2 years, and 46.7% and 33.1%, respectively, at 5 years or more (P<0.001 for all comparisons)...

Assessments of pharmacokinetic drug interactions and tolerability of albendazole, praziquantel and ivermectin combinations.

The pharmacokinetic interactions and tolerability of albendazole, praziquantel and ivermectin combinations were assessed in 23 healthy Thai volunteers (12 males and 11 females). The study was an open, randomised, three-way crossover design in which each subject attended the study on three separate occasions (Phases I, II and III), of 4 d or 8 d each, with at least 1 or 2 weeks (but not longer than 2 months) between each phase. All subjects received the three study drug regimens as follows: regimen I, oral praziquantel (40 mg/kg body weight); regimen II, oral ivermectin (200 microg/kg body weight) given concurrently with an oral dose of albendazole (400 mg); and regimen III, oral ivermectin given concurrently with albendazole and praziquantel. All treatment regimens showed acceptable tolerability profiles. The incidence of overall drug-related adverse events was significantly higher following regimens I (12/23) and III (7/23) compared with that following regimen II (0/23). Six statistically significant changes in the pharmacokinetic parameters of albendazole sulphoxide (Cmax, AUC0-infinity, Vz/F, CL/F), praziquantel (Vz/F) and ivermectin (AUC0-infinity) were observed when the three drugs were given concurrently. However, based on US Food and Drug Administration criteria, these changes were not considered of clinical relevance.

Macrofilaricides and onchocerciasis control, mathematical modelling of the prospects for elimination.

BACKGROUND: In most endemic parts of the world, onchocerciasis (river blindness) control relies, or will soon rely, exclusively on mass treatment with the microfilaricide ivermectin. Worldwide eradication of the parasite by means of this drug is unlikely. Macrofilaricidal drugs are currently being developed for human use. METHODS: We used ONCHOSIM, a microsimulation mathematical model of the dynamics of onchocerciasis transmission, to explore the potentials of a hypothetical macrofilaricidal drug for the elimination of onchocerciasis under different epidemiological conditions, as characterized by previous intervention strategies, vectorial capacity and levels of coverage. RESULTS: With a high vector biting rate and poor coverage, a very effective macrofilaricide would appear to have a substantially higher potential for achieving elimination of the parasite than does ivermectin. CONCLUSIONS: Macrofilaricides have a substantially higher potential for achieving onchocerciasis elimination than ivermectin, but high coverage levels are still key. When these drugs become available, onchocerciasis elimination strategies should be reconsidered. In view of the impact of control efforts preceding the introduction of macrofilaricides on the success of elimination, it is important to sustain current control efforts.

Anti-HIV-1 activity in vitro of ceftazidime degradation products.

Cephalosporins in aqueous solutions generate degradation products that inhibit in vitro HIV-1 replication in cell lines, as well as in primary cells (lymphocytes and macrophages). This effect is observed at concentrations that do not interfere with the normal functions of these cells. Upon chromatographic fractionation of an aqueous solution of hydrolysed ceftazidime, a high molecular weight fraction (MW 8000) with antiviral activity was isolated. The exact chemical nature of the active component responsible for the anti-HIV activity in vitro appears to be complex and is currently unknown. Inhibition of HIV-1 reverse transcriptase and RNase H activity was observed, however, higher concentrations than those needed to inhibit HIV replication were required. The inhibitory action of the hydrolysed ceftazidime was manifested during the early phase of the HIV-1 life-cycle. Despite a lack of a direct effect of the CD4/gp120 interaction, HIV-1 mediated cell fusion was inhibited by the hydrolysed ceftazidime, suggesting that the active principle acts in a very early stage of the viral life-cycle.

Call to consolidate achievements for onchocerciasis and lymphatic filariasis control.

The Bernhard Nocht Institute for Tropical Medicine and the UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases held an international conference to review recent achievements in research and control of onchocerciasis and lymphatic filariasis on 19-23 September 2001 in Hamburg, Germany.

Blocking HIV replication by targeting Tat protein.

BACKGROUND: A rapid development of viral drug resistance poses a serious limitation in the current drug development programs against HIV. In turn, this obstacle forms the basis for new efforts, which utilize alternative viral targets. RESULTS: By aiming at the Tat-driven process of HIV gene regulation, we discovered a new class of compounds as well as a novel target. The candidate compound acts on the one hand by classically inhibiting Tat/TAR complexation, however, without binding to nucleic acids. CONCLUSIONS: Structure and molecular modeling/dynamics suggest that the stilbene derivative CGA137053 directly binds to Tat protein but not TAR RNA. As a completely new, second property, the compound also antagonizes a TAR-independent activity of free Tat protein by preventing the recently described upregulation of the HIV coreceptor CXCR4. With the stilbene CGA137053, we have identified a potent, double-hitting and chemically feasible Tat antagonist. The compound possesses high target specificity and low cytotoxicity, is not restricted to the Tat/TAR axis of HIV inhibition and highly active on HIV-infected, primary human cells.

An analysis of the safety of the single dose, two drug regimens used in programmes to eliminate lymphatic filariasis.

This review of the safety of the co-administration regimens to be used in programmes to eliminate lymphatic filariasis (albendazole + ivermectin or albendazole + diethylcarbamazine [DEC]) is based on 17 studies conducted in Sri Lanka, India, Haiti, Ghana, Tanzania, Kenya, Ecuador, the Philippines, Gabon, Papua New Guinea, and Bangladesh. The total data set comprises 90,635 subject exposures and includes individuals of all ages and both genders. Results are presented for hospital-based studies, laboratory studies, active surveillance of microfilaria-positive and microfilaria-negative individuals, and passive monitoring in both community-based studies and mass treatment programmes of individuals treated with albendazole (n = 1538), ivermectin (9822), DEC (576), albendazole + ivermectin (7470), albendazole + DEC (69,020), or placebo (1144). The most rigorous monitoring, which includes haematological and biochemical laboratory parameters pre- and post-treatment, provides no evidence that consistent changes are induced by any treatment; the majority of abnormalities appear to be sporadic, and the addition of albendazole to either ivermectin or DEC does not increase the frequency of abnormalities. Both DEC and ivermectin show, as expected, an adverse event profile compatible with the destruction of microfilariae. The addition of albendazole to either single-drug treatment regimen does not appear to increase the frequency or intensity of events seen with these microfilaricidal drugs when used alone. Direct observations indicated that the level of adverse events, both frequency and intensity, was correlated with the level of microfilaraemia. In non microfilaraemic individuals, who form 80-90% of the 'at risk' populations to be treated in most national public health programmes to eliminate lymphatic filariasis (LF), the event profile with the compounds alone or in combination does not differ significantly from that of placebo. Data on the use of ivermectin + albendazole in areas either of double infection (onchocerciasis and LF), or of loiais (with or without concurrent LF) are still inadequate and further studies are needed. Additional data are also recommended for populations infected with Brugia malayi, since most data thus far derive from populations infected with Wuchereria bancrofti.

New aza-dipeptide analogues as potent and orally absorbed HIV-1 protease inhibitors: candidates for clinical development.

On the basis of previously described X-ray studies of an enzyme/aza-dipeptide complex,8 aza-dipeptide analogues carrying N-(bis-aryl-methyl) substituents on the (hydroxethyl)hydrazine moiety have been designed and synthesized as HIV-1 protease inhibitors. By using either equally (12) or orthogonally (13) protected dipeptide isosteres, symmetrically and asymmetrically acylated aza-dipeptides can be synthesized. This approach led to the discovery of very potent inhibitors with antiviral activities (ED50) in the subnanomolar range. Acylation of the (hydroxethyl)hydrazine dipeptide isostere with the L-tert-leucine derivative 29 increased the oral bioavailability significantly when compared to the corresponding L-valine or L-isoleucine derivatives. The bis(L-tert-leucine) derivatives CGP 75355, CGP 73547, CGP 75136, and CGP 75176 combine excellent antiviral activity with high blood concentration after oral administration. Furthermore, they show no cross-resistance with saquinavir-resistant strains and maintain activity against indinavir-resistant ones. Consequently they qualify for further profiling as potential clinical candidates.

In vitro effect of alpha1-acid glycoprotein on the anti-human immunodeficiency virus (HIV) activity of the protease inhibitor CGP 61755: a comparative study with other relevant HIV protease inhibitors.

Protein binding can impair the potency of human immunodeficiency virus (HIV) protease inhibitors. Therefore, the activity of a novel compound, CGP 61755, was studied in the absence or presence of alpha1-acid glycoprotein (alpha1AGP). In MT-2 cells, the activity loss was 4-fold (EC90 without alpha1AGP, 29 nM vs. 122 nM with alpha1AGP). In primary lymphocytes, the loss was 8-fold (EC90, 45 nM vs. 364 nM). In identical experiments, the activity loss in MT-2 cells and lymphocytes was 2- and 3-fold, respectively, for indinavir, 11- and 10-fold for saquinavir, and 11- and 48-fold for ritonavir. For SC-52151, a 17-fold loss was seen in MT-2 cells, whereas no EC90 with alpha1AGP was reached in lymphocytes. This study demonstrates that the impact of alpha1AGP on in vitro activity varies greatly among different HIV protease inhibitors. The magnitude of such differences is greater in human lymphocytes than in a standard cell line.

An inhibitor of the Tat/TAR RNA interaction that effectively suppresses HIV-1 replication.

One of the first steps in HIV gene expression is the recruitment of Tat protein to the transcription machinery after its binding to the RNA response element TAR. Starting from a pool of 3.2 x 10(6) individual chemical entities, we were able to select a hybrid peptoid/peptide oligomer of 9 residues (CGP64222) that was able to block the formation of the Tat/TAR RNA complex in vitro at nanomolar concentrations. NMR studies demonstrated that the compound binds similarly to polypeptides derived from the Tat protein and induces a conformational change in TAR RNA at the Tat-binding site. In addition, 10-30 microM CGP64222 specifically inhibited Tat activity in a cellular Tat-dependent transactivation assay [fusion-induced gene stimulation (FIGS) assay] and blocked HIV-1 replication in primary human lymphocytes. By contrast, peptides of a comparable size and side-chain composition inhibited cell fusion in the FIGS assay and only partially inhibited HIV-1 replication in primary human lymphocytes. Thus, we have discovered a compound, CGP64222, that specifically inhibits the Tat/TAR RNA interaction, both in vitro and in vivo.

Membrane tumor necrosis factor (TNF) induced cooperative signaling of TNFR60 and TNFR80 favors induction of cell death rather than virus production in HIV-infected T cells.

Tumor necrosis factor (TNF) and lymphotoxin (LT) are highly pleiotropic cytokines that play a central role in regulating HIV-1 replication. These cytokines express their activities through two membrane receptors, TNFR60 (p55-60) and TNFR80 (p75-80). In the present study we have demonstrated by means of antagonistic and agonistic receptor-specific antibodies that in latently infected lymphocytic (ACH-2) cells the TNFR60 plays a dominant role in signaling HIV production, although selective activation of TNFR80 by receptor-specific antibodies can also induce HIV production. Unexpectedly, when both TNFRs were activated simultaneously by agonistic antibodies or coculture with cells expressing a noncleavable membrane form of TNF, HIV production was downregulated and induction of cell death was enhanced in ACH-2 cells. More relevant, in vitro HIV-infected peripheral blood lymphocytes cocultured with cells expressing membrane TNF underwent rapid induction of apoptosis with a subsequent reduced HIV production of these lymphocytes cultures. This was not observed with HIV-infected lymphocytes treated with soluble TNF. These data provide evidence for the differential trigger potential of membrane versus soluble TNF and show that TNFR80 is an important modulator of TNF responsiveness of HIV-infected T cells via cooperative signaling with TNFR60.

Profile of CGP 61755: a novel and potent HIV-1 protease inhibitor that shows enhanced anti-HIV activity when combined with other antiretroviral agents in vitro.

CGP 61755 is a novel hydroxyethylene derivative produced by a high yield 10 step chemical synthesis. It is highly specific for HIV-1 protease with an IC50 of 1 nM. The ED90 in MT-2, PBLs and macrophages is infected with laboratory strains of HIV-1 or clinical isolates is 30-100 nM. In chronically infected macrophages the ED90 is 1000 nM (1000 nM for saquinavir and 10 microM for indinavir). When the antiviral activity of CGP 61755 on HIV-1 infected lymphocytes was examined using serum free medium an ED99 of 60 nM was determined, while in the presence of 10% human serum the same activity was achieved with 120 nM. When examined in combination with RT inhibitors or protease inhibitors, either in a co-culture of CEM-SS and chronically infected H9IIIB cells or in a free virus lymphocyte infection, cooperativity of the antiviral activities was observed. Dog pharmacokinetic studies comparing p.o. and i.v. data indicate that CGP 61755 has a bioavailability between 50 and 80%. Following oral administration the area under the concentration curve (AUC) values increased in a dose proportional manner. The plasma levels of the drug at 6 hours after oral administration were above the ED90. Based on these properties we believe that CGP 61755 has an attractive profile that justifies further preclinical evaluation of the drug.

Synthesis of potent and orally active HIV-protease inhibitors.

A series of potent HIV-protease inhibitors has been prepared. Several of the newly synthesized compounds showed high plasma even after oral administration to animals. Based on the overall biological profile, CGP 61755 was chosen for further preclinical evaluation. For this compound, a 10 step synthesis potentially suitable for large scale production was developed.

Compact dielectric reflective elements. II. Multichannel filter of closely spaced spectral bands.

The optical design of an interference wedge filter providing the simultaneous separation of a number of closely spaced spectral bands is studied. Multiple reflections of the incident collimated beam within the wedge are initiated, each of them characterized by a different angle of incidence and consequently by specific spectral parameters of the transmitted band. Model calculations based on the measured angular dependences of filter transmission parameters have been performed. The design is proposed for applications in optical communications (wavelength division demultiplexing), analytical spectroscopy (minipolychromators), color analysis, and similar areas.

Both mannose and beta-glucan receptors are involved in phagocytosis of unopsonized, heat-killed Saccharomyces cerevisiae by murine macrophages.

We studied the involvement of lectin-like receptors in phagocytosis of unopsonized heat-killed yeast (Saccharomyces cerevisiae) by murine macrophage-like cell lines and murine peritoneal resident macrophages. For this purpose we used a technique that allowed us to discriminate ingested and adsorbed heat-killed yeast. The internalization can be partly inhibited by soluble polyosides such as laminarin (beta-glucan) or alpha-mannan. However, when they were used together (0.4 mg/ml alpha-mannan and 0.4 mg/ml laminarin), almost complete inhibition of phagocytosis was obtained. These observations suggest that phagocytosis of unopsonized heat-killed yeast by murine macrophage-like cell lines as well as murine peritoneal resident macrophages is mediated by both mannose and beta-glucan receptors. The respective activity of these two types of receptors is a function of in vitro cell differentiation. To achieve maximal phagocytosis of unopsonized heat-killed yeast, coexpression of both mannose and beta-glucan receptors is required.

CGP 53437, an orally bioavailable inhibitor of human immunodeficiency virus type 1 protease with potent antiviral activity.

CGP 53437 is a peptidomimetic inhibitor of human immunodeficiency virus type 1 (HIV-1) protease containing a hydroxyethylene isostere. The compound inhibited recombinant HIV-1 protease with a Ki of 0.2 nM. The inhibition constant versus human cathepsin D and human cathepsin E was 4 nM. Human pepsin and gastricsin were inhibited with Kis of 8 and 500 nM, respectively, and human renin was inhibited with a Ki of 190 microM. The replication of HIV-1/LAV, HIV-1/Z-84, and HIV-1/pLAI was inhibited with a 90% effective dose of 0.1 microM in acutely infected MT-2 cells. The 50% cytotoxic dose was 100 microM. Similar antiviral activity was observed when the compound was added up to 10 h after infection. At the effective concentration, processing of Gag precursor protein p55 was greatly reduced, confirming an action on the late stage of the virus life cycle, as expected. The efficacy of the inhibitor was also demonstrated by using primary human peripheral blood lymphocytes infected with the HIV-1/LAV strain, low-passage clinical isolates obtained from HIV-1-seropositive individuals (including a zidovudine-resistant strain), and HIV-2/ROD. In these cells, CGP 53437 delayed the onset of HIV replication in a dose-dependent fashion (substantial effects with concentrations of > or = 0.1 microM) as long as the inhibitor was maintained in the culture. CGP 53437 was orally bioavailable in mice. Concentrations in plasma 10-fold in excess of the in vitro antiviral 90% effective dose could be sustained for several hours after oral application of 120 mg/kg. Therefore, CGP 53437 has the potential to be a therapeutically useful anti-HIV agent for the treatment of AIDS.

The replicative restriction of lymphocytotropic isolates of HIV-1 in macrophages is overcome by TGF-beta.

In vitro exposure of human blood monocyte-derived macrophages to T-cell tropic human immunodeficiency virus (HIV) isolates fails to establish a productive viral infection. Several studies have shown that such preferential HIV-1 replication in T cells or in mononuclear phagocytes (HIV tropism) may be determined by distinct viral characteristics. In the present study it was demonstrated that transforming growth factor-beta (TGF-beta), a factor known to be produced by platelets, macrophages, and other cells present at a wound site, can act as a mediator in overcoming the lymphocytotropic restriction of several well-characterized viral isolates of HIV-1 (i.e., LAV, Z84, pLAI, NY5). Macrophages infected with these isolates show cytopathic changes comparable to those seen upon infection with the monocytotropic isolate ADA. To achieve this effect with TGF-beta, the factor must be present after the infection period. The emerging virus retains its original cellular tropism. Based on these observations the authors propose a role for TGF-beta in the establishment and progression of HIV infection and disease.

Recombinant human C5a induces transcription but not translation of interleukin 1 beta mRNA in human monocytes.

The effect of recombinant human C5a (rhC5a) on the synthesis of interleukin 1 beta (IL-1 beta) was investigated in human monocytes, isolated by leukapheresis and countercurrent elutriation. rhC5a induced IL-1 beta mRNA synthesis in a dose- and time-dependent manner. Maximal induction was achieved at 3 h with rhC5a concentrations of 200 to 500 ng/ml. The maximal rhC5a-stimulated mRNA induction was about 75% of that observed using LPS as the stimulus (300 ng/ml). The inducing activity of rhC5a could be neutralized by preincubation with a polyclonal anti-C5a antibody. On the other hand rhC5a in optimal concentrations only weakly stimulated IL-1 beta protein synthesis, as measured by a two-site directed enzyme-linked immunoassay. When compared on Northern blots, a slightly reduced mobility of C5a-stimulated IL-1 beta mRNA was observed relative to LPS-stimulated RNA. To exclude the possibility that structural defects in the IL-1 beta mRNA are responsible for the weak translational efficiency after C5a stimulation a primer extension experiment was performed. No difference in the length of the extended fragment was detected between LPS and C5a-stimulated RNA, suggesting that the 5'-regions of the RNAs are identical. When LPS- or C5a-stimulated RNA was used to program IL-1 beta synthesis in an in vitro translation system from rabbit reticulocytes, no difference in translational efficiency was observed. Our results indicate that in human monocytes two signals for IL-1 beta gene expression are necessary, a signal for transcriptional activation and another signal to induce translation of the mRNA.