Aromatic antiepileptic drugs and mitochondrial toxicity: Effects on mitochondria isolated from rat liver

Idiosyncratic hepatotoxicity is a well-known complication associated with aromatic antiepileptic drugs (AAED), and it has been suggested to occur due to the accumulation of toxic arene oxide metabolites. Although there is clear evidence of the participation of an immune process, a direct toxic effect involving mitochondria dysfunction is also possible. The effects of AAED on mitochondrial function have not been studied yet. Therefore, we investigated, in vitro, the cytotoxic mechanism of carbamazepine (CB), phenytoin (PT) and phenobarbital (PB), unaltered and bioactivated, in the hepatic mitochondrial function. The murine hepatic microsomal system was used to produce the anticonvulsant metabolites. All the bioactivated drugs (CB-B, PB-B, PT-B) affected mitochondrial function causing decrease in state three respiration, RCR, ATP synthesis and membrane potential, increase in state four respiration as well as impairment of Ca(2+) uptake/release and inhibition of calcium-induced swelling. As an unaltered drug, only PB, was able to affect mitochondrial respiration (except state four respiration) ATP synthesis and membrane potential; however, Ca(2+) uptake/release as well as swelling induction were not affected. The potential to induce mitochondrial dysfunction was PT-B > PB-B > CB-B > PB. Results suggest the involvement of mitochondrial toxicity in the pathogenesis of AAED-induced hepatotoxicity. (C) 2008 Elsevier Ltd. All rights reserved.

Non-steroidal anti-inflammatory drugs may modulate the protease activity of Candida albicans

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Beef Carcass Contamination by Shiga Toxin-Producing Escherichia coli Strains in an Abattoir in Brazil: Characterization and Resistance to Antimicrobial Drugs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of non-steroidal anti-inflammatory drugs (NSAID) on the histamine release induced by compound 48/80 and cardiac anaphylaxis in guinea-pig isolated heart

Histamine release from guinea pig heart treated with compound 48/80 was potentiated by the cyclooxygenase inhibitors indomethacin and piroxicam but not by aspirin or phenylbutazone. This differential effect suggests that the potentiation is not merely due to an inhibition of prostaglandin synthesis. Piroxicam potentiated the histamine release induced by cardiac anaphylaxis whereas indomethacin reduced this effect. The SRS-A antagonist FPL 55712 inhibited histamine release induced by cardiac anaphylaxis, but not that evoked by compound 48/80, and also prevented the potentiation due to indomethacin and piroxicam. In total, these data suggest that the potentiation of histamine release by piroxicam and indomethacin is probably due to a diversion of arachidonic acid metabolism from the cyclooxygenase to the lipoxygenase pathways. The resulting lipoxygenase products may then regulate histamine release, with the secretion due to antigen being more sensitive to such modulation than that evoked by compound 48/80.

Probing the binding of the coumarin drugs using peptide fragments of DNA gyrase B protein

Bacterial DNA gyrase, has been identified as the target of several antibacterial agents, including the coumarin drugs. The coumarins inhibit the gyrase action by competitive binding to the ATP-binding site of DNA gyrase B (GyrB) protein. The high in vitro inhibitory potency of coumarins against DNA gyrase reactions has raised interest in studies on coumarin-gyrase interactions. In this context, a series of low-molecular weight peptides, including the coumarin resistance-determining region of subunit B of Escherichia coli gyrase, has been designed and synthesized. The first peptide model was built using the natural fragment 131-146 of GyrB and was able to bind to novobiocin (K a = 1.8 ± 0.2 × 105/M) and ATP (Ka = 1.9 ± 0.4 × 103/M). To build the other sequences, changes in the Arg136 residue were introduced so that the binding to the drug was progressively reduced with the hydrophobicity of this residue (Ka = 1.3 ± 0.1 × 105/M and 1.0 ± 0.2 × 105/M for Ser and His, respectively). No binding was observed for the change Arg136 to Leu. In contrast, the binding to ATP was not altered, independently of the changes promoted. On the contrary, for peptide-coumarin and peptide-ATP complexes, Mg2+ appears to modulate the binding process. Our results demonstrate the crucial role of Arg 136 residue for the stability of coumarin-gyrase complex as well as suggest a different binding site for ATP and in both cases the interactions are mediated by magnesium ions. Copyright Blackwell Munksgaard, 2005.

Propolis: anti-Staphylococcus aureus activity and synergism with antimicrobial drugs

Propolis is a natural resinous substance collected by bees from tree exudates and secretions. Its antimicrobial activity has been investigated and inhibitory action on Staphylococcus aureus growth was evaluated The in vitro synergism between ethanolic extract of propolis (EEP) and antimicrobial drugs by two susceptibility tests (Kirby and Bauer and E-Test) on 25 S. aureus strains was evaluated Petri dishes with sub-inhibitory concentrations of EEP were incubated with 13 drugs using Kirby and Bauer method and synergism between EEP and five drugs [choramphenicol (CLO), gentamicin (GEN), netilmicin (NET), tetracycline (TET), and vancomycin (VAN)] was observed. Nine drugs were assayed by the E-test method and five of them exhibited a synergism [CLO, GEN, NET, TET, and clindamycin (CLI)]. The results demonstrated the synergism between EEP and antimicrobial drugs, especially those agents that interfere on bacterial protein synthesis.

Horseradish peroxidase-catalyzed oxidation of rifampicin: Reaction rate enhancement by co-oxidation with anti-inflammatory drugs

The tuberculostatic drug rifampicin has been described as a scavenger of reactive species. Additionally, the recent demonstration that oral therapy with a complex of rifampicin and horseradish peroxidase (HRP) was more effective than rifampicin alone, in an animal model of experimental leprosy, suggested the importance of redox reactions involving rifampicin and their relevance to the mechanism of action. Hence, we studied the oxidation of rifampicin catalyzed by HRP, since this enzyme may represent the prototype of peroxidation-mediated reactions. We found that the antibiotic is efficiently oxidized and that rifampicin-quinone is the product, in a reaction dependent on both HRP and hydrogen peroxide. The steady-state kinetic constants Km app (101±23 mmol/l), Vmax app (0.78±0.09 μmol/l·s-1) and kcat (5.1±0.6 s-1) were measured (n=4). The reaction rate was increased by the addition of co-substrates such as tetramethylbenzidine, salicylic acid, 5-aminosalicylic acid and paracetamol. This effect was explained by invoking an electron-transfer mechanism by which these drugs acted as mediators of rifampicin oxidation. We suggested that this drug interaction might be important at the inflammatory site. © 2005 Pharmaceutical Society of Japan.

Immune reconstitution in HIV-1 infected patients treated for two years with highly active antiretroviral therapy

The aim of this paper was to evaluate the immune reconstitution of HIV-1 patients subjected to highly active antiretroviral therapy (HAART) for two years or more according to CD 45RA and CD 45RO cell count; determination of IL-2, IFN-γ, IL-4, IL-10 and TNF-α serum levels; CD 4 + T and CD 8 + T lymphocyte count; and plasma viral load (VL) determination. For this purpose, a cross sectional study was carried out in the Tropical Diseases Area, Botucatu School of Medicine, São Paulo State University, UNESP, Botucatu, São Paulo, Brazil. Between June 2001 and April 2002, 37 HIV-1 infected patients were evaluated, 13 with treatment indication but untreated (G1), 9 subjected to HAART for 5-7 months (G2), and 15 treated for two years or more (G3); both treated groups used medication regularly and without failure. Forty-nine normal individuals were studied as controls (GC-1 and GC-2). There was a tendency (p<0.10) for the predominance of two nucleoside reverse transcriptase inhibitors (NRTI) associated with one non-nucleoside reverse transcriptase inhibitor (NNRTI) regimen in G2; and two NRTI associated with a protease inhibitor (PI) in G3. Statistical differences between groups were seen for CD 45RA (G1<[G3=GC-2]; p<0.05) and CD 45RO (G1[G2=G3]; p<0.001), TNF-α serum determination ([G1>G3; G2=intermediate]>GC-1; p<0.001), IL-2 (G1<[G2=G3=GC-1]; p<0.01), IFN-γ ([G1=GC-1]>[GC-2=G3]; p<0.001), IL-4 and IL-10 ([G1=G2=G3]>GC-1; p<0.001), serum cytokine profiles, with a higher proportion of subtype 2 in G1 and mature subtype 0 in G2 and G3 (p<0.005). There was no statistical difference for CD 8 + T lymphocyte counts (G1=G2=G3; p<0.50). Consistency was seen between positive correlations of profile 1 definer cytokines (IL-2 and IFN-γ), CD 45RA and CD 45RO cells, and CD 4 + T lymphocyte counts and between positive correlations of profile 2 definer cytokines (IL-4 and IL-10) with TNF-α, and VL. The negative correlations were also consistent as they expressed the inverse of the positives. The variables with the highest number of correlations were IL-2, IFN-γ, and VL, followed by CD 45RA and CD 45RO cells, and IL-10. The variables with the lowest number of correlations were CD 4 + T and CD 8 + T lymphocytes. The results express the partial but important immune reconstitution in HIV-1 infected individuals with the interference of HAART and the importance of cytokines especially IL-2 and IFN-γ, and CD 45RA and CD 45RO cells as surrogate markers of this reconstitution.

Bezafibrate for the treatment of hypertriglyceridemia in HIV1-infected patients on highly active antiretroviral therapy

The use of highly active antiretroviral therapy (HAART) in HIV-infected patients has been associated with the development of risk factors for cardiovascular diseases (CD) including dyslipidemia and insulin resistance, hypertriglyceridemia being the most frequent metabolic disturbance in these patients. Fibrates are indicated when hypertriglyceridemia is accentuated and persists for over six months. We evaluated the efficacy and safety of bezafibrate for the treatment of hypertriglyceridemia in HIV-infected individuals on HAART. All patients received 400mg/day of bezafibrate and were evaluated three times: Mo (pre-treatment), M1 (one month after treatment), and M2 (six months after treatment). Fifteen adult individuals, eight males and seven females with mean age = 41.2 ± 7.97 years and triglyceride serum levels ≥400mg/dL were included in the study. Smoking, alcohol ingestion and sedentarism rates were 50%, 6.66% and 60%, respectively. Family history of CD, hypertension and diabetes mellitus was reported in 33.3%, 40% and 46.7% of the cases, respectively, while dyslipidemia was reported by only 13.3%. More than half of the patients were using a protease inhibitor plus a nucleotide analog transcriptase inhibitor. Eutrophy and tendency toward overweight were observed at all three study time points. There were significant reductions in triglyceride serum levels from Mo to M1 and from Mo to M2. No significant changes were observed in the serum levels of creatine phosphokinase, hepatic enzymes, CD4 +, CD8 + and viral load. Therefore, bezafibrate seems to be safe and effective for the reduction of hypertriglyceridemia in HIV-infected patients on HAART. © 2006 by The Brazilian Journal of Infectious Diseases and Contexto Publishing. All rights reserved.

Vernonia polyanthes as a new source of antiulcer drugs

Methanolic (VPME) and chloroformic (VPCL) extracts, obtained from the aerial parts of Vernonia polyanthes, were investigated for its antiulcerogenic properties. Administration of VPME (250 mg/kg) and VPCL (50 mg/kg) significantly inhibited the gastric mucosa damage (64% and 90%, respectively) caused by absolute ethanol (p.o.). Otherwise, in NSAID-induced gastric damage, their gastroprotective effects have decreased. Since the VPCL extract resulted to be more effective than the VPME we focused our efforts over VPCL action mechanism of action. © 2007 Elsevier B.V. All rights reserved.

Surface-enhanced Raman scattering (SERS) applied to cancer diagnosis and detection of pesticides, explosives, and drugs

The inelastic scattering of light, Raman scattering, presents a very low cross section. However, the signal can be amplified by several orders of magnitude, leading to the so-called surface-enhanced Raman scattering (SERS) phenomenon. Basically, the SERS effect is achieved when the target molecule (analyte) is adsorbed onto metallic nanoparticles, usually noble metals. This article presents an overview of the applications of SERS to cancer diagnosis and the detection of pesticides, explosives, and drugs (illicit and pharmacological). SERS is routinely applied nowadays to detect and identify analytes at very low concentrations, including for single-molecule detection. However, the application of SERS as an analytical tool requires reliable and reproducible SERS substrates, in terms of enhancement factors, which depends on the size, shape, and aggregation of the metallic nanoparticles. Therefore, the production of reliable and reproducible SERS substrates is a challenge in the field. Besides, the metallic nanoparticles can also induce changes in the system by possible interactions with the analyte under investigation, which must be taken into account. This review will present work in which, under certain specific experimental conditions, SERS has been analytically applied.

In Vitro Susceptibility of Environmental Isolates of Exophiala dermatitidis to Five Antifungal Drugs

Several dematiaceous fungi frequently isolated from nature are involved in cases of superficial lesions to lethal cerebral infections. Antifungal susceptibility data on environmental and clinical isolates are still sparse despite the advances in testing methods. The objective of this study was to examine the activities of 5-flucytosine, amphotericin B, itraconazole, voriconazole and terbinafine against environmental isolates of Exophiala strains by minimum inhibition concentration (MIC) determination. The strains were obtained from hydrocarbon-contaminated soil, ant cuticle and fungal pellets from the infrabuccal pocket of attine gynes. Broth microdilution assay using M38-A2 reference methodology for the five antifungal drugs and DNA sequencing for fungal identification were applied. Terbinafine was the most active drug against the tested strains. It was observed that amphotericin B was less effective, notably against Exophiala spinifera, also studied. High MICs of 5-flucytosine against Exophiala dermatitidis occurred. This finding highlights the relevance of studies on the antifungal resistance of these potential opportunistic species. Our results also contribute to a future improvement of the standard methods to access the drug efficacy currently applied to black fungi. © 2012 Springer Science+Business Media Dordrecht.