Evaluation of hydroxyurea genotoxicity in patients with sickle cell disease / Avaliação da indução de genotoxicidade pela hidroxiureia em pacientes com doença falciforme

ABSTRACT Objective To evaluate the induction of DNA damage in peripheral blood mononuclear cells of patients with sickle cell disease, SS and SC genotypes, treated with hydroxyurea. Methods The study subjects were divided into two groups: one group of 22 patients with sickle cell disease, SS and SC genotypes, treated with hydroxyurea, and a Control Group composed of 24 patients with sickle cell disease who were not treated with hydroxyurea. Peripheral blood samples were submitted to peripheral blood mononuclear cell isolation to assess genotoxicity by the cytokinesis-block micronucleus cytome assay, in which DNA damage biomarkers - micronuclei, nucleoplasmic bridges and nuclear buds - were counted. Results Patients with sickle cell disease treated with hydroxyurea had a mean age of 25.4 years, whereas patients with sickle cell disease not treated with hydroxyurea had a mean age of 17.6 years. The mean dose of hydroxyurea used by the patients was 12.8mg/kg/day, for a mean period of 44 months. The mean micronucleus frequency per 1,000 cells of 8.591±1.568 was observed in the Hydroxyurea Group and 10.040±1.003 in the Control Group. The mean frequency of nucleoplasmic bridges per 1,000 cells and nuclear buds per 1,000 cells for the hydroxyurea and Control Groups were 0.4545±0.1707 versus 0.5833±0.2078, and 0.8182±0.2430 versus 0.9583±0.1853, respectively. There was no statistically significant difference between groups. Conclusion In the study population, patients with sickle cell disease treated with the standard dose of hydroxyurea treatment did not show evidence of DNA damage induction.

RESUMO Objetivo Avaliar o efeito da indução de danos ao DNA em células monocelulares do sangue periférico de pacientes com doença falciforme, genótipos SS e SC, tratados com hidroxiureia. Métodos Os sujeitos da pesquisa foram divididos em dois grupos: um de 22 pacientes com doença falciforme genótipos SS e SC tratados com hidroxiureia, e o outro controle, composto por 24 pacientes com doença falciforme que não eram tratados com o fármaco. As amostras de sangue periférico foram submetidas ao isolamento de células mononucleares do sangue periférico para avaliação da genotoxicidade pelo ensaio de micronúcleo citoma com bloqueio da citocinese, tendo sido quantificados os biomarcadores de danos ao DNA - micronúcleos, pontes nucleoplasmáticas e brotamento nuclear. Resultados Os pacientes com doença falciforme tratados com hidroxiureia apresentaram média de idade de 25,4 anos, enquanto aqueles com doença falciforme não tratados com hidroxiureia tiveram média de idade de 17,6 anos. A dose média de hidroxiureia utilizada pelos pacientes foi de 12,8mg/kg/dia, por período médio de 44 meses. A frequência média de micronúcleos por 1.000 células de 8,591±1,568 foi observada no Grupo Hidroxiureia e de 10,040±1,003 no Grupo Controle. Adicionalmente, a frequência média de pontes nucleoplasmáticas por 1.000 células e brotamento nuclear por 1.000 células para o Grupo Hidroxiureia e Controle foi de 0,4545±0,1707 versus 0,5833±0,2078, e de 0,8182±0,2430 versus 0,9583±0,1853, respectivamente. Não houve diferença estatisticamente significativa entre os grupos. Conclusão Na população estudada de pacientes com doença falciforme com tratamento em dose padrão de hidroxiureia, não houve evidência de indução de danos ao DNA.

ERG11 gene polymorphisms and susceptibility to fluconazole in candida isolates from diabetic and kidney transplant patients

Abstract INTRODUCTION: Candidiasis is the most frequent opportunistic mycosis in humans and can cause mortality, particularly in immunodeficient patients. One major concern is the increasing number of infections caused by drug-resistant Candidas trains, as these cannot be efficiently treated with standard therapeutics. The most common mechanism of fluconazole resistance in Candida is mutation of ERG11, a gene involved in the biosynthesis of ergosterol, a compound essential for cell integrity and membrane function. METHODS: Based on this knowledge, we investigated polymorphisms in the ERG11 gene of 3 Candida species isolated from immunocompromised and immunocompetent patients. In addition, we correlated the genetic data with the fluconazole susceptibility profile of the Candida isolates. RESULTS: A total of 80 Candida albicans, 8 Candida tropicalis and 6 Candida glabrata isolates were obtained from the saliva of diabetic, kidney transplant and immunocompetent patients. Isolates were considered susceptible to fluconazole if the minimum inhibitory concentration was lower than 8 μg/mL. The amino acid mutations F105L, D116E, K119N, S137L, and K128T were observed in C. albicans isolates, and T224C and G263A were found in C. tropicalis isolates. CONCLUSIONS: Despite the high number of polymorphisms observed, the mutations occurred in regions that are not predicted to interfere with ergosterol synthesis, and therefore are not related to fluconazole resistance.

Mechanistic effect of the human GJB6 gene and its mutations in HaCaT cell proliferation and apoptosis

We constructed lentiviral vectors containing the human wild-type GJB6 gene and the mutant variants A88V and G11R. The three proteins were stably expressed by the Tet-on system in the HaCaT cell line and used to study the functional effect of the variants. The CCK-8 assay and flow cytometric analyses were used to determine the levels of cell proliferation and apoptosis. Western blot analyses were performed to analyze the relevant clinical indicators of hidrotic ectodermal dysplasia and markers of apoptosis in transfected HaCaT cells. The CCK8 assay and the flow cytometry results showed a significant increase (P<0.05) in the apoptosis of HaCaT cells expressing the A88V and G11R mutants. In addition, we demonstrated that the A88V and G11R mutants induced the apoptosis of transfected HaCaT cells via the activation of caspase-3, -8, -9, and PARA. No change was observed in the activity of BAX compared with the control. This study provides further clarification on the mechanisms underlying the effect of the mutant variants A88V and G11R of the GJB6 gene on the induction of HaCaT cell apoptosis.

Análisis genético de las mutaciones presentes en las poblaciones virales en pacientes con infección por VIH-1 en Ecuador / Genetic analysis of the mutations in HIV-1 infected population in Ecuador

Resumen Introducción Las recomendaciones internacionales de tratamiento anti-retroviral incluyen pruebas de resistencia para orientar el régimen de tratamiento en cada paciente, lo que no está disponible de forma estable en Ecuador. Objetivo Describir las mutaciones que confieren resistencia a anti-retrovirales en una población de pacientes ecuatorianos. Metodología A partir de muestras de plasma de 101 pacientes con VIH-1 con fallo a la terapia anti-retroviral, 15 niños y 86 adultos, se realizó pirosecuenciación con el GS Junior (Roche) y se analizaron las secuencias con el programa DeepChek. Resultados Las mutaciones más frecuentes fueron M184V/I, K101E/P/H, K103N/S, D30N, M46L/I, I54L/M, V82T/F/A/S/L y L90M en adultos, y F77L, K103N/S, M46L/I, V82T/F/A/S/L y L90M en niños. Se encontró una elevada resistencia a los inhibidores de la transcriptasa reversa (TR) no análogos de nucleósidos en poblaciones minoritarias virales de adultos y niños (34,9 y 70%, respectivamente), en los niños, tanto las poblaciones virales mayoritarias como minoritarias, fueron resistente a inhibidores de proteasa (> 45%). Los pacientes que tuvieron un mayor número de esquemas terapéuticos presentaron mayores niveles de resistencia a los anti-retrovirales. La mayoría de las muestras fueron del subtipo B en la región de la TR y proteasa, y CRF25_cpx en integrasa. Conclusiones Se muestran las mutaciones y la resistencia a antiretrovirales en una población de pacientes ecuatorianos con infección por VIH-1, que permitirán realizar un llamado de alerta a las autoridades de salud sobre la necesidad de realizar estudios de resistencia.

Background The international recommendations of antiretroviral treatment include resistance tests to guide the treatment regimen in each patient, which is not available on a regular basis in Ecuador. Aim To describe mutations that confer resistance to antiretrovirals in a population of Ecuadorian patients. Methods Plasma samples from 101 HIV-1 patients with failure to antiretroviral therapy, divided into 15 children and 86 adults, were studied with the GS Junior (Roche) and the sequences were analyzed with the DeepChek program. Results The most frequent mutations were M184V/I, K101E/P/H, K103N/S, D30N, M46L/I, I54L/M, V82T/F/A/S/L and L90M in adults and F77L, K103N/S, M46L/I, V82T/F/A/S/L and L90M in children. High resistance to non-nucleoside reverse transcriptase (RT) inhibitors in minority viral populations of adults and children (34.9% and 70%) was detected; in children both viral populations (majority and minority viral populations) (> 45%) were protease inhibitor resistant. Patients who had a greater number of therapeutic regimens had higher levels of resistance to antiretrovirals. Most of the samples were subtype B in the TR and protease region, and CRF25_cpx in integrase. Conclusions Mutations and resistance to antiretrovirals are shown in a population of Ecuadorian patients with HIV-1. These results will make it possible to issue a warning to health authorities about the need for resistance studies.

Vernonanthura polyanthes leaves aqueous extract enhances doxorubicin genotoxicity in somatic cells of Drosophila melanogaster and presents no antifungal activity against Candida spp / O extrato aquoso das folhas de Vernonanthura polyanthes potencializa a genotoxicidade da doxorrubicina em células somáticas de Drosophila melanogaster e não apresenta atividade antifúngica contra Candida spp

Abstract Vernonanthura polyanthes (Spreng.) A.J. Vega & Dematt. (Asteraceae), known as “assa-peixe”, has been used in ethnomedicine for the treatment of various diseases such as bronchitis, pneumonia, hemoptysis, persistent cough, internal abscesses, gastric and kidney stone pain. Moreover, some studies demonstrated that species of Genus Vernonia present antifungal activity. Due to the biological relevance of this species, the aim of this study was to investigate the toxic, genotoxic, antigenotoxic and antifungal potential of V. polyanthes leaves aqueous extract in somatic cells of Drosophila melanogaster or against Candida spp. The aqueous extract of the plant showed no toxic, genotoxic and antigenotoxic activity in the experimental conditions tested using the wing somatic mutation and recombination test (SMART/wing). However, when the extract was associated with doxorubicin, used in this work as a positive control, the mutagenic potential of doxorubicin was enhanced, increasing the number of mutations in D. melanogaster somatic cells. In the other hand, no inhibitory activity against Candida spp. was observed for V. polyanthes leaves aqueous extract using agar-well diffusion assay. More studies are necessary to reveal the components present in the V. polyanthes leaves aqueous extract that could contribute to potentiate the doxorubicin genotoxicity.

Resumo Vernonanthura polyanthes (Spreng.) A.J. Vega & Dematt. (Asteraceae), conhecida como “assa-peixe”, tem sido utilizada na medicina popular para o tratamento de várias doenças, como bronquite, pneumonia, hemoptise, tosse persistente, abcessos internos, afecções gástricas e cálculo renal. Além disso, alguns estudos já demonstraram que espécies do Gênero Vernonia apresentam atividade antifúngica. Devido à relevância biológica dessa espécie, o objetivo deste estudo foi investigar os efeitos citotóxico, genotóxico, antigenotóxico e antifúngico do extrato aquoso das folhas de V. polyanthes em células somáticas de Drosophila melanogaster ou contra Candida spp. O extrato aquoso da planta não apresentou atividade citotóxica, genotóxica e antigenotóxica nas condições experimentais testadas usando o teste de recombinação e mutação somática em asa (SMART-asa). No entanto, quando o extrato foi associado com a doxorrubicina, utilizada neste trabalho como controle positivo, o potencial mutagênico da doxorrubicina foi potencializado, aumentando o número de mutações em células somáticas de D. melanogaster. Por outro lado, nenhuma atividade inibitória contra Candida spp. foi observada utilizando o extrato aquoso das folhas de V. polyanthes por meio do método de difusão em ágar. Mais estudos são necessários para desvendar os componentes presentes no extrato aquoso das folhas de V. polyanthes que possam contribuir para potencializar a genotoxicidade da doxorrubicina.

Oseltamivir-resistant influenza A(H1N1)pdm2009 strains found in Brazil are endowed with permissive mutations, which compensate the loss of fitness imposed by antiviral resistance

The 2009 pandemic influenza A virus outbreak led to the systematic use of the neuraminidase (NA) inhibitor oseltamivir (OST). Consequently, OST-resistant strains, carrying the mutation H275Y, emerged in the years after the pandemics, with a prevalence of 1-2%. Currently, OST-resistant strains have been found in community settings, in untreated individuals. To spread in community settings, H275Y mutants must contain additional mutations, collectively called permissive mutations. We display the permissive mutations in NA of OST-resistant A(H1N1)pdm09 virus found in Brazilian community settings. The NAs from 2013 are phylogenetically distinct from those of 2012, indicating a tendency of positive selection of NAs with better fitness. Some previously predicted permissive mutations, such as V241I and N369K, found in different countries, were also detected in Brazil. Importantly, the change D344N, also predicted to compensate loss of fitness imposed by H275Y mutation, was found in Brazil, but not in other countries in 2013. Our results reinforce the notion that OST-resistant A(H1N1)pdm09 strains with compensatory mutations may arise in an independent fashion, with samples being identified in different states of Brazil and in different countries. Systematic circulation of these viral strains may jeopardise the use of the first line of anti-influenza drugs in the future. (AU)

Antiviral therapy against chronic hepatitis B in Brazil: high rates of lamivudine resistance mutations and correlation with HBV genotypes

The effectiveness of antiviral treatments of chronic hepatitis B has been poorly studied in Brazil. Here, hepatitis B virus (HBV) DNA positivity, drug resistance mutations and their association with HBV genotypes were evaluated in chronically HBV-infected patients under different drug regimens in Brazil. The study involved 129 patients under interferon or nucleos(t)ide analogue therapy for a median treatment time of 12 months. One hundred and five (81%) of these patients were treated with lamivudine (LAM), either in monotherapy or in combination with newer drugs, such as entecavir (ETV) or tenofovir (TDF). High (37.5-100%) rates of HBV DNA positivity were observed with all but one drug regimen (LAM + ETV). However, patients that were treated with ETV alone, TDF alone or with LAM combination therapies had a mean viral load that was 3-4 log lower than patients treated with LAM monotherapy. Of the patients treated with LAM, 47% developed resistance mutations. HBV genotypes A (59.1%), D (30.3%) and F (9.1%) were found. There was no association between the presence of LAM resistance mutations and genotypes, HBeAg status or treatment duration. Nevertheless, the rtM204V mutation was observed more frequently (12/13, 92%) in genotype A than in the others (p = 0.023). Six out of nine isolates that contained the rtM204I mutation belonged to genotype D and half of them displayed a single mutation. Genotype D isolates with the rtM204V variant preferentially displayed a triple mutation, while genotype A preferentially displayed a double mutation (p = 0.04).

Chronic ethanol consumption in mice does not induce DNA damage in somatic or germ cells, evaluated by the bone marrow micronucleous assay and the dominant lethal mutation assay

Although alcohol is known to be a carcinogen for humans, ethanol-genotoxicity studies are incomplete. Ethanol seems not to be a bacterial mutagen, but the results are conflicting in rodent assays. We investigate the genotoxicity in the bone marrow micronucleus (MN) test and in the dominant lethal mutation (DLM) assay using two long-term ethanol exposure protocols. In the MN test, mice consumed three doses (5, 10 and 15% v/v) for 32 weeks. MN induction was compared to two control groups of 5- and 38-week-old mice (the ages of the treated mice when the treatment was initiated and when they were killed, respectively). For the three groups treated with ethanol there was no significant increase in MN induction as compared to the first control group, but observed MN frequencies were significantly lower than in the 38-week-old control group. This suggests a protective effect against genotoxic damage caused by aging, probably due to ethanol action as a hydroxyl radical scavenger. In the DLM assay, male mice drank ethanol at 15% or 30% (v/v) for 20 weeks. In both groups the number of dead implants was similar to the control, but there was a significant reduction in total implants, indicating a pre-implantation loss.

QRDR mutations, efflux system & antimicrobial resistance genes in enterotoxigenic Escherichia coli isolated from an outbreak of diarrhoea in Ahmedabad, India.

Background & objectives: Diverse mechanisms have been identified in enteric bacteria for their adaptation and survival against multiple classes of antimicrobial agents. Resistance of bacteria to the most effective fluoroquinolones have increasingly been reported in many countries. We have identified that most of the enterotoxigenic Escherichia coli (ETEC) were resistant to several antimicrobials in a diarrhoea outbreak at Ahmedabad during 2000. The present study was done to identify several genes responsible for antimicrobial resistance and mobile genetic elements in the ETEC strains. Methods: Seventeen ETEC strains isolated from diarrhoeal patients were included in this study. The antimicrobial resistance was confirmed by conventional disc diffusion method. PCR and DNA sequencing were performed for the identification of mutation in the quinolone resistance-determining regions (QRDRs). Efflux pump was tested by inhibiting the proton-motive force. DNA hybridization assay was made for the detection of integrase genes and the resistance gene cassettes were identified by direct sequencing of the PCR amplicons. Results: Majority of the ETEC had GyrA mutations at codons 83 and 87 and in ParC at codon 80. Six strains had an additional mutation in ParC at codon 108 and two had at position 84. Plasmid-borne qnr gene alleles that encode quinolone resistance were not detected but the newly described aac(6’)-Ib-cr gene encoding a fluoroquinolne-modifying enzyme was detected in 64.7 per cent of the ETEC. Class 1 (intI1) and class 2 (intI2) integrons were detected in six (35.3%) and three (17.6%) strains, respectively. Four strains (23.5%) had both the classes of integrons. Sequence analysis revealed presence of dfrA17, aadA1, aadA5 in class 1, and dfrA1, sat1, aadA1 in class 2 integrons. In addition, the other resistance genes such as tet gene alleles (94.1%), catAI (70.6%), strA (58.8%), blaTEM-1(35.2%), and aphA1-Ia (29.4%) were detected in most of the strains. Interpretation & conclusions: Innate gene mutations and acquisition of multidrug resistance genes through mobile genetic elements might have contributed to the emergence of multidrug resistance (MDR) in ETEC. This study reinforces the necessity of utilizing molecular techniques in the epidemiological studies to understand the nature of resistance responsible for antimicrobial resistance in different species of pathogenic bacteria.

Long-term response to sulfonylurea in a patient with diabetes due to mutation in the KCNJ11 gene / Resposta a longo prazo com sulfonilureia em um paciente com diabetes associado à mutação no gene KCNJ11

OBJECTIVE: To report the long-term (30-month) effect of the switch from insulin to sulfonylurea in a patient carrying the p.G53D (c.158G>A) mutation in KCNJ11 gene. SUBJECT AND METHOD: A 29-year-old male patient was diagnosed with diabetes in the third month of life and after identification of a heterozygous p.G53D mutation in the KCNJ11 gene, the therapy was switched from insulin to sulfonylurea. RESULTS: Long-term follow-up (30 months) showed that good metabolic control was maintained (HbA1c: 6.6 percent) and the glibenclamide dose could be reduced. CONCLUSION: Long-term therapy with sulfonylureas in patients with neonatal diabetes due to mutation in the KCNJ11 gene is safe and promotes sustained improvement of glycemic control.

OBJETIVO: Reportar o efeito a longo prazo (30 meses) da substituição de insulina por sulfonilureia em um paciente com a mutação p.G53D (c.158G>A) no gene KCNJ11. SUJEITO E MÉTODO: Paciente do sexo masculino, atualmente com 29 anos de idade, foi diagnosticado com diabetes melito no terceiro mês de vida e, após identificação da mutação p.G53D (c.158G>A) em heterozigose no gene KCNJ11, a terapia foi substituída de insulina para sulfonilureia. RESULTADOS: Seguimento a longo prazo (30 meses) mostrou que o bom controle metabólico foi mantido (HbA1c: 6,6 por cento) e a dose de glibenclamida pode ser reduzida. CONCLUSÃO: A terapia com sulfonilureia a longo prazo em pacientes com diabetes neonatal decorrente de mutações no gene KCNJ11 é segura e promove uma melhora persistente no controle metabólico.

Analysis of resistance testing in South Trinidad / Análisis de prueba de resistencia en Trinidad Sur

The introduction of antiretroviral therapy in Trinidad and Tobago in the 1980s has resulted in a decrease in mortality of HIV-infected persons. Poor adherence to antiretroviral therapy (ART) has resulted in the development of multidrug resistant HIV. Resistance testing done on 40 samples showed that 64.8% of patients had K103 mutation, 75.6% of patients had M184 mutations and 62% of patients showed resistance to tenofovir suggesting that the K65R mutation was highly likely to be present. There was reduced activity to the protease inhibitors; no resistance was found to the protease inhibitor, darunavir. Thus, there is a need for salvage therapy to be introduced which will result in virologic suppression and potentially stop the spread of multidrug resistant HIV. Darunavir, a new generation protease inhibitor, is an essential part of salvage therapy and needs to be introduced into the national formulary.

La introducción de la terapia antiretroviral en Trinidad y Tobago en la década de 1980, ha producido una disminución en la mortalidad de personas infectadas por el VIH. La adhesión pobre a la terapia antiretroviral (TAR) ha conducido al desarrollo de una variedad de VIH resistente a las multidrogas. Las pruebas de resistencia realizadas a 40 muestras mostró que el 64.8% de los pacientes tenían mutación K103, 75.6% de los pacientes tenían mutaciones M184, y 62% de pacientes mostraron resistencia al tenofovir, lo que indica una alta probabilidad de mutación K65R. Había actividad reducida respecto a los inhibidores de la proteasa; mientras que no se halló ninguna resistencia en el inhibidor de la protease, darunavir. Así, hay necesidad de introducir una terapia de salvamento qué produzca una supresión virológica y potencialmente detenga la diseminación del VIH resistente a las multidrogas. El darunavir - inhibidor de nueva generación frente a la proteasa -es una parte fundamental de la terapia de salvamento y necesita ser introducido en el formulario nacional.

Prevalencia de resistencia primaria en pacientes con infección reciente por VIH-1 en Chile / Prevalence of primary antiretroviral resistance among HIV infected patients in Chile

Background: The main cause of virological failure during AIDS treatment is the resistance to antiretroviral medications (ARV). Aim: To search for mutations associated with ARV resistance in recently HIV-1 infected patients naïve to treatment, in Chile. Material and Methods: Patients over 18 years old with HIV-1 infection, naïve to antiretroviral drugs before the study were included. Patients with CD4 cell counts less than 200 cells/mm³, viral load below 2.000 copies/mL or any condition indicative of advanced AIDS were excluded. Criteria for diagnosis of recent infection (< 18 months) were a previous negative test for HIV antibodies or a history of an acute retroviral syndrome in the past 18 months. Resistance to drugs was analyzed using the TRUGENEtm HIV-1 assay from Bayer and the OpenGene DNA sequencing system. Results: Ninety nine percent of patients had at least one mutation, 27 percent had 4 or more mutations, but high level resistance to ARV was found only in 2.7 percent of cases. Point mutations for non nucleoside reverse transcriptase inhibitors (NNRTI) were detected in 4.1 percent of cases (K103N in 1 patient, V179D in 2 patients), for nucleoside reverse transcriptase inhibitors (NRTI) in 8.1 percent of cases (T215S in 1 patient, V118I in 4 patients, M41L in 1 patient) and for protease inhibitors (PI) in 1.3 percent of cases. All mutations detected in the protease gene were secondary. Of these, the most common were L63P/T (38 patients), L10I/V (27 patients) and V77I (26 patients). Resistance to two or more antiretroviral classes was not detected. Conclusions: This study supports that, by now, primary resistance has a low prevalence in Chile. Therefore, a genotyping test before starting antiretroviral therapy is not necessary.

Characterisation of pvmdr1 and pvdhfr genes associated with chemoresistance in Brazilian Plasmodium vivax isolates

Plasmodium vivax control is now being hampered by drug resistance. Orthologous Plasmodium falciparum genes linked to chloroquine or sulfadoxine-pyrimethamine chemoresistance have been identified in P. vivax parasites, but few studies have been performed. The goal of the present work is to characterise pvmdr1 and pvdhfr genes in parasite isolates from a Brazilian endemic area where no molecular investigation had been previously conducted. The pvmdr1 analysis revealed the existence of single (85.7 percent) and double (14.3 percent) mutant haplotypes, while the pvdhfr examination showed the presence of double (57.2 percent) and triple (42.8 percent) mutant haplotypes. The implications of these findings are discussed.

Resistencia a metronidazol y claritromicina en aislamientos de Helicobacter pylori de pacientes dispépticos en Colombia / Antimicrobial susceptibility of Helicobacter pylori strains isolated in Colombia

Background: Helicobacter pylori antimicrobial resistance rates differ among countries and even between different areas of a country. In Colombia, the most commonly used antimicrobials for the treatment of H pylori infection are amoxicillin, clarithromycin and metronidazole. Aim: To determine antimicrobial susceptibility of H pylori strains isolated in Colombia. Materials and methods: Eighty eight strains of H pylori were isolated and identified by microbiological methods and confirmed with polymerase chain reaction (PCR). The detection of antimicrobial resistance to amoxicillin, clarithromycin, metronidazole and tetraclycline, was conducted by the Etest method. Mutations in the 23S rDNA, involved in resistance to clarithromycin, were detected using PCR and restriction fragment lenght polymorphism. Results: Eighty eight and 2.2 percent of the strains were resistant to metronidazole and clarithromycin, respectively. No isolate was simultaneously resistant to amoxicillin or tetracycline. The two clarithromycin resistant strains were homozygous for the A2143G mutation. No mutations were found in the remaining 86 susceptible strains. Conclusions: The high rate of metronidazole resistance in our population precludes the use of this drug for the empirical treatment of Hpylori infection.

Molecular analysis of hprt mutation in B6C3F1 mice exposed to ozone alone and combined treatment of 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone and/or dibutyl phthalate for 32 and 52 weeks

Potential toxicological interactions of 4-(N-methyl-N-nitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and/or dibuthyl phthalate (DBP) on ozone were investigated after 32- and 52-wk exposures using hprt mutation assay. Male and female B6C3F1 mice exposed to ozone (0.5 ppm), NNK (1.0 mg/kg), DBP (5,000 ppm), and two or three combinations of these toxicants 6 h per day for 32- and 52-wk showed increases in the frequencies of TG rlymphocytes compared to the control groups. Additive interactions were noted from two combination groups compared to the ozone alone in both sexes of 32- and 52-wk studies. The most common specific mutation type in the hprt genes of test materials-treated male and female mice was transversion with very few transition. The results indicate that such dominant transversion may be responsible for toxicity and combined exposure to ozone, NNK, and DBP induces additive genotoxicities compared to ozone alone.

Prevalence of primary and secondary resistant mutations to antiretroviral drug in a population of Puerto Rican infected with HIV

INTRODUCTION: Several studies have reported increasing number of therapeutic failures with HAART in HIV-infected individuals. In order to assess the impact HIV antiretroviral resistance could have on treatment, we decided to determine the prevalence of primary and secondary antiretroviral resistant genotypes in a population of HIV-infected Puerto Ricans and compare the mutational distribution pattern with that reported in Europe and US. METHOD: In a total of 80 plasma samples from patients with detectable viral load of over 1,000 RNA copies/ml, the Trugene Visible Genetics HIV sequencing method was used to detect antiretroviral resistance mutations. RESULTS: We found 55 subjects (69 per cent) with high level of resistance to ZDV in the reverse transcriptase gene and 46 subjects (58 per cent) with high level of resistance to NFV in the protease gene. Mutation frequencies to the NRTI ranged in appearance from as high as 54 per cent (i.e., M184V) in the studied subjects to a low of less than 5 per cent (i.e., M184I and V75T). For the NNRTI the most common mutation was K103N in 40 per cent of the subjects and found to confer cross resistance to NVP, DLV and EFV. Another concerning finding is the increasing trend of the frequency of primary and secondary resistant mutations from year 2000 to 20001. Nine (23 per cent) of the total detected primary mutations, to either RTI or PI, showed an increase of at least 5 per cent from one year to the other. Similarly, there were 6 (11 per cent) secondary resistant mutations showing an increase of at least 5 per cent during the two years studied. CONCLUSIONS: In two year period we detected a tendency to increase in primary and secondary HIV-resistant mutation in a population of HIV-infected Puerto Ricans.

Reversion mutation in dark variants of luminous bacteria and its application in gene toxicant monitoring / 华中科技大学学报（医学）（英德文版）

The luminous intensity of dark variant (S1) separated from photobacterium phosphoreum (A2) was 1/10,000 less than that of wild-type. Ethidium bromide (EB) (0.6 mg/L), Mytomycin C (MC, 0.05 mg/L), 2-amino fluorene (2-AF, 1.0 mg/L) all could strongly induce reversion mutation for S1 within 24 h and increase reversion ratio significantly. The results of experiments indicated that these revertants had stable genetic characteristic and the mutation may take place at gene levels. The mutagenesis to S1 caused by EB, MC and 2-AF was detected and it may be used as a new rapid, simple and sensitive method for gene toxicant monitoring.

Characterization and mapping of an informational suppressor in Aspergillus nidulans

The present work was undertaken to characterize a suppressor gene present in a mutant strain of A. nidulans obtained with NTG (N-Methyl-N'-Nitro-N-Nitrosoguanidine). Analyses of this mutant have shown that this suppressor, designated suO1, induces phenotypic co-reversion of several auxotrophic mutations and makes the strain sensitive to aminoglycoside antibiotics and lower temperatures. suO1 has shown to be on linkage group VIII. The vegetative growth of the mutant strain is very unstable because the suppressor gene induces the production of prototrophic mitotic sectors. The strains bearing the suO1 gene produce cleistothecia containing a reduced number of viable ascospores during the sexual cycle. The segregation of the genetic markers has also been observed in the mutant strain self crossed. From the above results it may be concluded that suO1 is an informational suppressor.