RESUMEN
Classical mechanisms of volcanic eruptions mostly involve pressure buildup and magma ascent towards the surface1. Such processes produce geophysical and geochemical signals that may be detected and interpreted as eruption precursors1-3. On 22 May 2021, Mount Nyiragongo (Democratic Republic of the Congo), an open-vent volcano with a persistent lava lake perched within its summit crater, shook up this interpretation by producing an approximately six-hour-long flank eruption without apparent precursors, followed-rather than preceded-by lateral magma motion into the crust. Here we show that this reversed sequence was most likely initiated by a rupture of the edifice, producing deadly lava flows and triggering a voluminous 25-km-long dyke intrusion. The dyke propagated southwards at very shallow depth (less than 500 m) underneath the cities of Goma (Democratic Republic of the Congo) and Gisenyi (Rwanda), as well as Lake Kivu. This volcanic crisis raises new questions about the mechanisms controlling such eruptions and the possibility of facing substantially more hazardous events, such as effusions within densely urbanized areas, phreato-magmatism or a limnic eruption from the gas-rich Lake Kivu. It also more generally highlights the challenges faced with open-vent volcanoes for monitoring, early detection and risk management when a significant volume of magma is stored close to the surface.
RESUMEN
Em seres humanos, a adiponectinemia está associada à obesidade e ao risco aumentado a uma ampla variedade de cânceres. Embora o papel dessa adipocina esteja bem documentado na patogênese do câncer em humanos, tal associação permanece a ser determinada em cães. Nesses animais, a relação da adiponectina com a carcinogênese parece ser ainda meramente especulativa. Nesse contexto, buscou-se nesta investigação comparar os níveis séricos de adiponectina em fêmeas hígidas e em portadoras de carcinomas mamários com diagnóstico histopatológico de carcinoma mamário tubular simples estágio 4, com comprometimento de linfonodos, porém sem metástases a distância detectadas. Foi observado que as cadelas diagnosticadas com carcinoma mamário tiveram níveis séricos de adiponectina significativamente menores (média de 3,72±1,54µg/mL, P<0,05) em relação às fêmeas consideradas hígidas (média de 5,61±2,18µgl/mL), sugerindo associação entre câncer e hipoadiponectinemia similar à encontrada em humanos. Em relação à idade e ao peso corporal dos animais do estudo, não foi encontrada diferença significativa entre os grupos. Os resultados encontrados nas cadelas portadoras de carcinoma mamário do presente estudo corroboram a associação já descrita em humanos entre ocorrência de carcinogênese e baixos níveis de adiponectina.(AU)
Asunto(s)
Animales , Femenino , Perros , Adenocarcinoma/sangre , Adenocarcinoma/veterinaria , Adiponectina , Obesidad/complicaciones , Obesidad/veterinariaRESUMEN
Introducción y objetivo: El síndrome metabólico (SM) comprende un conjunto de factores de riesgo para las enfermedades cardiovasculares y la diabetes. Argentina cuenta con numerosos estudios epidemiológicos sobre SM y, sin embargo, no se ha realizado un análisis sistemático de la prevalencia de SM en nuestra población. Con el fin de estimar la prevalencia de SM en la República Argentina se realizó una revisión sistemática de los estudios observacionales publicados durante el período 1988-2014. Estrategia de búsqueda: Se realizó una búsqueda bibliográfica en las bases de datos MEDLINE (National Library of Medicine), SciELO (Scientific Electronic Library Online) y LILACS (Latin American and Caribbean Health Sciences Literature) sobre estudios realizados en Argentina entre enero de 1988 y diciembre de 2014. Se utilizaron los siguientes términos de búsqueda combinados en los idiomas inglés, castellano y portugués: «síndrome metabólico», «insulinorresistencia», «síndrome dismetabólico», «prevalencia», «epidemiología», «Argentina». Selección de estudios: Fueron incluidos en el análisis los estudios epidemiológicos basados en población adulta de la República Argentina con reporte de la prevalencia de SM (de acuerdo con los criterios de la OMS, ATPIII o IDF). Síntesis de resultados: En la búsqueda bibliográfica inicial se identificaron 400publicaciones. En la segunda fase de búsqueda, 296títulos y resúmenes fueron excluidos. En la tercera fase, se analizó el texto completo de 104estudios. Finalmente, se incluyeron 6 publicaciones en el análisis que reportaron la prevalencia de SM sobre un total de 10.191sujetos (39,6% varones). La edad media de la población fue de 45,2años. La prevalencia de SM (modelo de efectos aleatorios) fue del 27,5% (IC 95%: 21,3-34,1%). La prevalencia de SM fue más elevada en varones que en mujeres (29,4% vs. 27,4%, respectivamente; p=0,02). En orden de frecuencia, los componentes de SM más comunes fueron la dislipidemia (38,3%), la presión arterial elevada (33,4%), la obesidad (32,1%) y la diabetes (7,5%). Conclusiones: Nuestros datos muestran que la prevalencia de SM es alta, lo que representa un problema de salud pública muy importante en Argentina (AU)
Introduction and aim: Metabolic syndrome (MS) comprises a set of risk factors for cardiovascular disease and diabetes. Argentina has numerous epidemiological studies on MS, however, there has been no systematic analysis of the prevalence of MS in our population. To estimate the prevalence of MS in the Argentine Republic, a systematic review of observational studies published during the period 1988-2014 was carried out. Search strategy: A bibliographic search was conducted in the MEDLINE (National Library of Medicine), SciELO (Scientific Electronic Library Online) and LILACS (Latin American and Caribbean Health Sciences Literature) databases on studies conducted in Argentina between January 1989 and December 2014. The following search terms were combined in English, Spanish and Portuguese: 'metabolic syndrome', 'insulin resistance', 'dysmetabolic syndrome', 'prevalence', 'epidemiology', and 'Argentina'. Selection of studies: Epidemiological studies based on the adult population of Argentina with specific report of the prevalence of MS (according to the WHO, ATP III or IDF criteria) were included in the analysis. Synthesis results: In the initial bibliographic search, 400 publications were identified. In the second phase of search, 296 titles and abstracts were excluded. In the third phase, the full text of 104 studies was analyzed. Finally, 6 publications were included in the analysis that reported the prevalence of MS in a total of 10,191 subjects (39.6% male). The average age of the population was 45.2 years. The prevalence of MS (random effects model) was 27.5% (95% CI: 21.3%-34.1%). The prevalence of MS was higher in men than in women (29.4% vs. 27.4%, respectively, P=.02). In order of frequency, the most common components of MS were dyslipidaemia (38.3%), hypertension (33.4%), obesity (32.1%) and diabetes (7.5%). Conclusions: Our data show that the prevalence of MS is high, which represents a very important public health problem in Argentina (AU)
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Humanos , Masculino , Femenino , Síndrome Metabólico/epidemiología , Diagnóstico Precoz , Enfermedades Cardiovasculares/epidemiología , Enfermedades Cardiovasculares/prevención & control , Argentina/epidemiología , Indicadores de MorbimortalidadRESUMEN
INTRODUCTION AND AIM: Metabolic syndrome (MS) comprises a set of risk factors for cardiovascular disease and diabetes. Argentina has numerous epidemiological studies on MS, however, there has been no systematic analysis of the prevalence of MS in our population. To estimate the prevalence of MS in the Argentine Republic, a systematic review of observational studies published during the period 1988-2014 was carried out. SEARCH STRATEGY: A bibliographic search was conducted in the MEDLINE (National Library of Medicine), SciELO (Scientific Electronic Library Online) and LILACS (Latin American and Caribbean Health Sciences Literature) databases on studies conducted in Argentina between January 1989 and December 2014. The following search terms were combined in English, Spanish and Portuguese: 'metabolic syndrome', 'insulin resistance', 'dysmetabolic syndrome', 'prevalence', 'epidemiology', and 'Argentina'. SELECTION OF STUDIES: Epidemiological studies based on the adult population of Argentina with specific report of the prevalence of MS (according to the WHO, ATP III or IDF criteria) were included in the analysis. SYNTHESIS RESULTS: In the initial bibliographic search, 400 publications were identified. In the second phase of search, 296 titles and abstracts were excluded. In the third phase, the full text of 104 studies was analyzed. Finally, 6 publications were included in the analysis that reported the prevalence of MS in a total of 10,191 subjects (39.6% male). The average age of the population was 45.2 years. The prevalence of MS (random effects model) was 27.5% (95% CI: 21.3%-34.1%). The prevalence of MS was higher in men than in women (29.4% vs. 27.4%, respectively, P=.02). In order of frequency, the most common components of MS were dyslipidaemia (38.3%), hypertension (33.4%), obesity (32.1%) and diabetes (7.5%). CONCLUSIONS: Our data show that the prevalence of MS is high, which represents a very important public health problem in Argentina.
Asunto(s)
Síndrome Metabólico/epidemiología , Estudios Observacionales como Asunto , Argentina/epidemiología , Humanos , Resistencia a la Insulina , Morbilidad/tendencias , Vigilancia de la Población , PrevalenciaRESUMEN
O estresse oxidativo causa peroxidação lipídica e formação de substâncias reativas ao ácido tiobarbitúrico (TBARS), processo que está comprovadamente associado à progressão de neoplasias malignas em seres humanos. Por sua vez, espécies reativas de oxigênio (EROs) são produzidas no processo carcinogênico, de forma que a geração de EROs parece ser, ao mesmo tempo, causa e consequência dele. Em cães, a associação da peroxidação lipídica com a carcinogênese permanece ainda obscura, com estudos escassos, de resultados conflitantes, que, muitas vezes, incluem, dentro de um mesmo grupo amostral, animais portadores de tumores heterogêneos dos pontos de vista morfológico e comportamental, além de estes se apresentarem em estágios bastante distintos. Nesse contexto, buscou-se, na presente investigação, avaliar a concentração plasmática de TBARS em fêmeas hígidas e portadoras de carcinomas mamários com diagnóstico histopatológico de carcinoma mamário tubular simples estágio 4, com comprometimento de linfonodos, porém sem metástases detectadas. Foi observado que as cadelas diagnosticadas com carcinoma mamário tiveram níveis plasmáticos de TBARS significativamente maiores (média de 7,98 ± 1,43µmol/mL, p < 0,0001) em relação às fêmeas consideradas hígidas (média de 6,14 ± 0,53µmol/mL), o que sugere associação entre câncer e maior ocorrência de estresse oxidativo.(AU)
Asunto(s)
Animales , Femenino , Perros , Peroxidación de Lípido , Neoplasias Mamarias Animales/fisiopatología , Estrés Oxidativo , Sustancias Reactivas al Ácido Tiobarbitúrico/análisisRESUMEN
The calcified aortic stenosis is the dominating valve disease. Patients affected are most common elderly people in the 8 (th) or 9 (th) decade of their life who often show associated comorbidities like reduced left ventricular function, impaired renal function, pulmonary hypertension, and further diseases (Diabetes mellitus, stroke, COPD). In many cases perioperative morbidity and mortality are too high for surgical valve replacement and up to 30 % of patients are rejected. Nevertheless, prognosis of aortic stenosis is worse if the typical symptoms like dyspnea on exertion, syncope, and angina occur. The transcatheter aortic valve implantation is a new method treating this particular group of patients. The aortic valve bioprothesis consists of a balloon-expandable stent or a self-expandable frame, in which a valve of bovine or porcine pericardium is incorporated. The implantation is performed by retrograde access via the femoral or subclavian artery; the balloon-expandable prosthesis can also be implanted by transapical approach. Recently, the PARTNER trial and other studies demonstrate a high implantation success rate and better survival in comparison to standard therapy but exhibit also cerebral vascular and peripheral vascular complications. A further reduction of the available delivery systems and new types of valves which are under experimental tests and clinical evaluation contribute to this development.
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Estenosis de la Válvula Aórtica/cirugía , Calcinosis/cirugía , Cateterismo Cardíaco/métodos , Procedimientos Endovasculares/métodos , Implantación de Prótesis de Válvulas Cardíacas/métodos , Anciano de 80 o más Años , Estenosis de la Válvula Aórtica/diagnóstico , Aortografía , Bioprótesis , Calcinosis/diagnóstico , Cateterismo Cardíaco/instrumentación , Cateterismo , Conducta Cooperativa , Disnea/etiología , Ecocardiografía , Ecocardiografía Doppler , Ecocardiografía Transesofágica , Procedimientos Endovasculares/instrumentación , Femenino , Implantación de Prótesis de Válvulas Cardíacas/instrumentación , Humanos , Comunicación Interdisciplinaria , Cuidados Paliativos , Complicaciones Posoperatorias/diagnóstico , Diseño de PrótesisRESUMEN
Laboratories use pigmentation, antibiotic susceptibility, and biochemical tests to identify anaerobic organisms that play a role in bovine interdigital necrobacillosis (bovine foot rot). In this study, 16S rRNA gene sequencing was used to identify strains to the species level that were originally classified as Prevotella or Porphyromonas spp by conventional phenotype assessment methods. Of 264 qualified strains from ceftiofur clinical trials, 241 isolates were definitively identified by 16S rRNA sequencing as Porphyromonas levii. Similarly, of 275 qualified strains from tulathromycin clinical trials, 156 isolates were definitively identified by 16S rRNA sequencing as P. levii. The predominance of P. levii in this study supports the role of this organism as an associative agent of bovine foot rot and may have implications for routine laboratory diagnosis.
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Infecciones por Bacteroidaceae/veterinaria , Enfermedades de los Bovinos/microbiología , Enfermedades del Pie/veterinaria , Porphyromonas/genética , Porphyromonas/aislamiento & purificación , ARN Ribosómico 16S/genética , Animales , Infecciones por Bacteroidaceae/microbiología , Bovinos , Enfermedades del Pie/microbiologíaRESUMEN
TR-701 is the orally active prodrug of TR-700, a novel oxazolidinone that demonstrates four- to eightfold-greater activity than linezolid (LZD) against Staphylococcus and Enterococcus spp. In this study evaluating the in vitro sensitivity of LZD-resistant isolates, TR-700 demonstrated 8- to 16-fold-greater potency than LZD against all strains tested, including methicillin-resistant Staphylococcus aureus (MRSA), strains of MRSA carrying the mobile cfr methyltransferase gene, and vancomycin-resistant enterococci. The MIC(90) for TR-700 against LZD-resistant S. aureus was 2 microg/ml, demonstrating the utility of TR-700 against LZD-resistant strains. A model of TR-700 binding to 23S rRNA suggests that the increased potency of TR-700 is due to additional target site interactions and that TR-700 binding is less reliant on target residues associated with resistance to LZD.
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Acetamidas/farmacología , Antibacterianos/farmacología , Farmacorresistencia Bacteriana , Enterococcus/efectos de los fármacos , Oxazolidinonas/farmacología , Staphylococcus aureus/efectos de los fármacos , Antibacterianos/química , Antibacterianos/metabolismo , Sitios de Unión , Humanos , Linezolid , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Pruebas de Sensibilidad Microbiana/normas , Modelos Moleculares , Oxazolidinonas/química , Oxazolidinonas/metabolismo , Profármacos/química , Profármacos/farmacologíaRESUMEN
The manipulation of the antiferromagnetic interlayer coupling in epitaxial Fe/Cr/Fe(001) trilayers by 5 keV He ion beam irradiation has been investigated. It is shown that even for irradiation with low fluences a drastic change in strength of the coupling appears. For thin Cr spacers (below 0.6-0.7 nm) it decreases with fluence, becoming ferromagnetic for fluences above 2x10(14) ions/cm(2). The effect is connected with the creation of magnetic bridges in the layered system due to atomic exchange events caused by the bombardment. For thicker Cr spacers an enhancement of the antiferromagnetic coupling strength is found. A possible explanation of the enhancement effect is given.
RESUMEN
Through computationally directed broad screening, a novel 1, 5-diphenylpyrazole (DPP) class of HIV-1 nonnucleoside reverse transcriptase inhibitors (NNRTIs) has been discovered. Compound 2 (PNU-32945) was found to have good activity versus wild-type (IC(50) = 2.3 microM) and delavirdine-resistant P236L (IC(50) = 1.1 microM) reverse transcriptase (RT). Also, PNU-32945 has an ED(50) for inhibition of viral replication in cell cultures of 0.1 microM and was shown to be noncytotoxic with a CC(50) > 10 microM. Structure-activity relationship studies on the 3- and 4-positions of PNU-32945 led to interesting selectivity and activity within the class. In particular, the 3-hydroxyethyl-4-ethyl congener 29 is a potent inhibitor of the P236L mutant (IC(50) = 0.65 microM), whereas it is essentially inactive versus the wild-type enzyme (IC(50) > 50 microM). Furthermore, this compound was significantly more active versus the P236L mutant than delavirdine. The synthesis and RT inhibitory activity of various 3- and 4-substituted analogues are discussed.
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Fármacos Anti-VIH/farmacología , Delavirdina/farmacología , Transcriptasa Inversa del VIH/antagonistas & inhibidores , Pirazoles/síntesis química , Inhibidores de la Transcriptasa Inversa/síntesis química , Farmacorresistencia Microbiana , Transcriptasa Inversa del VIH/genética , Mutación , Pirazoles/química , Pirazoles/farmacología , Inhibidores de la Transcriptasa Inversa/química , Inhibidores de la Transcriptasa Inversa/farmacología , Relación Estructura-ActividadRESUMEN
A series of pyrimidine thioethers was synthesized and evaluated for inhibitory properties against wild-type HIV-1 reverse transcriptase (RT) and an RT carrying the resistance-conferring mutation P236L. Modifications of both the pyrimidine and the functionality attached through the thioether yielded several analogues, which demonstrated activity against both enzyme types, with IC50 values as low as 190 nM against wild-type and 66 nM against P236L RT. Evaluation of a select number of pyrimidine thioethers in cell culture showed that these compounds have excellent activity against HIV-1IIIB-WT and retain good activity against a laboratory-derived HIV-1MF delavirdine-resistant variant.
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Fármacos Anti-VIH , Delavirdina/farmacología , Transcriptasa Inversa del VIH/antagonistas & inhibidores , Pirimidinas , Inhibidores de la Transcriptasa Inversa , Inhibidores de la Transcriptasa Inversa/síntesis química , Sulfuros , Sustitución de Aminoácidos , Animales , Fármacos Anti-VIH/síntesis química , Fármacos Anti-VIH/química , Fármacos Anti-VIH/farmacología , Línea Celular , Farmacorresistencia Microbiana , Transcriptasa Inversa del VIH/genética , VIH-1/efectos de los fármacos , VIH-1/enzimología , Leucina/genética , Ratones , Prolina/genética , Pirimidinas/síntesis química , Pirimidinas/química , Pirimidinas/farmacología , Inhibidores de la Transcriptasa Inversa/química , Inhibidores de la Transcriptasa Inversa/farmacología , Relación Estructura-Actividad , Sulfuros/síntesis química , Sulfuros/química , Sulfuros/farmacologíaAsunto(s)
Fármacos Anti-VIH/farmacología , VIH-1 , Piridinas/farmacología , Pirimidinas/farmacología , Inhibidores de la Transcriptasa Inversa/farmacología , Animales , Fármacos Anti-VIH/síntesis química , Fármacos Anti-VIH/farmacocinética , Línea Celular , Farmacorresistencia Microbiana , Transcriptasa Inversa del VIH/antagonistas & inhibidores , Transcriptasa Inversa del VIH/genética , VIH-1/efectos de los fármacos , VIH-1/enzimología , Masculino , Mutación , Piridinas/síntesis química , Piridinas/farmacocinética , Pirimidinas/síntesis química , Pirimidinas/farmacocinética , Ratas , Ratas Sprague-Dawley , Inhibidores de la Transcriptasa Inversa/síntesis química , Inhibidores de la Transcriptasa Inversa/farmacocinética , EstereoisomerismoRESUMEN
PNU-140690 is a member of a new class of nonpeptidic human immunodeficiency virus (HIV) protease inhibitors (sulfonamide-containing 5,6-dihydro-4-hydroxy-2-pyrones) discovered by structure-based design. PNU-140690 has excellent potency against a variety of HIV type 1 (HIV-1) laboratory strains and clinical isolates, including those resistant to the reverse transcriptase inhibitors zidovudine or delavirdine. When combined with either zidovudine or delavirdine, PNU-140690 contributes to synergistic antiviral activity. PNU-140690 is also highly active against HIV-1 variants resistant to peptidomimetic protease inhibitors, underscoring the structural distinctions between PNU-140690 and substrate analog protease inhibitors. PNU-140690 retains good antiviral activity in vitro in the presence of human plasma proteins, and preclinical pharmacokinetic studies revealed good oral bioavailability. Accordingly, PNU-140690 is a candidate for clinical evaluation.
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Inhibidores de la Proteasa del VIH/farmacología , VIH-1/efectos de los fármacos , Piridinas/farmacología , Pironas/farmacología , Fármacos Anti-VIH/farmacología , Antivirales/farmacología , Células Cultivadas , Delavirdina , Combinación de Medicamentos , Evaluación Preclínica de Medicamentos , Sinergismo Farmacológico , Genotipo , VIH-1/genética , Humanos , Indoles/farmacología , Piperazinas/farmacología , Inhibidores de la Transcriptasa Inversa/farmacología , Sulfonamidas , Replicación Viral/efectos de los fármacos , Zidovudina/farmacologíaRESUMEN
Selection of the IIIB strain of human immunodeficiency virus type (HIV-1) resistant to the (alkylamino)piperidine-bis(heteroaryl)piperazine (AAP-BHAP) U-104489 results in substitution of a glycine to glutamate at residue 190 (G190E) of reverse transcriptase (RT). The AAP-BHAP resistant HIV-1 displays reduced in vitro replication capacity [Olmsted, R. A., et. al. (1966) J. Virol. 70, 3698-3705]. We report here that the G190E mutation in recombinant heterodimeric HIV-1 RT, compared to the wild-type RT (G190) or a G190A control mutant, results in a 40% and 80% reduction in the polymerase and RNase H specific enzymatic activities, respectively. A primer-extension assay that allowed determination of DNA elongation by the G190E mutant RT on a heteropolymeric HIV-1 gag-based RNA template showed an overall decrease in DNA polymerization. The size distribution of products generated by G190E RT-associated RNase H digestion of RNA from [35S]poly(rA).poly(dT) was markedly distinct from that of the G190A RT and was consistent with the observed reduction in RT-associated RNase H activity of the G190E RT. When challenged with unlabeled substrates, the G190E RT was relatively nonprocessive with respect to DNA synthesis and RNA degradation. It is concluded that the deleterious effect of the G190E resistance mutation on both of these RT functions is most likely involved in the observed retarded replication capacity of the AAP-BHAP-(U-104489-) resistant HIV-1.
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Replicación del ADN , ADN Viral/biosíntesis , Farmacorresistencia Microbiana , VIH-1/enzimología , Mutación Puntual , ARN Viral/metabolismo , ADN Polimerasa Dirigida por ARN/genética , ADN Polimerasa Dirigida por ARN/metabolismo , Secuencia de Bases , Clonación Molecular , Cartilla de ADN , Transcriptasa Inversa del VIH , VIH-1/genética , VIH-1/metabolismo , Humanos , Cinética , Sustancias Macromoleculares , Datos de Secuencia Molecular , Mutagénesis Sitio-Dirigida , Reacción en Cadena de la Polimerasa , Proteínas Recombinantes/metabolismo , Lugares Marcados de Secuencia , Especificidad por SustratoRESUMEN
The (alkylamino)piperidine bis(heteroaryl)piperizines (AAP-BHAPs) are a new class of human immunodeficiency virus type 1 (HIV-1)-specific inhibitors which were identified by targeted screening of recombinant reverse transcriptase (RT) enzymes carrying key nonnucleoside reverse transcriptase inhibitor (NNRTI) resistance-conferring mutations and NNRTI-resistant variants of HIV-1. Phenotypic profiling of the two most potent AAP-BHAPs, U-95133 and U-104489, against in vitro-selected drug-resistant HIV-1 variants carrying the NNRTI resistance-conferring mutation (Tyr->Cys) at position 181 of the HIV-1 RT revealed submicromolar 90% inhibitory concentration estimates for these compounds. Moreover, U-104489 demonstrated potent activity against BHA-P-resistant HIV-1MF harboring the Pro-236->Leu RT substitution and significantly suppressed the replication of clinical isolates of HIV-1 resistant to both delavirdine (BHAP U-90152T) and zidovudine. Biochemical and phenotypic characterization of AAP-BHAPresistant HIV-1IIIB variants revealed that high-level resistance to the AAP-BHAPs was mediated by a Gly-190->Glu substitution in RT, which had a deleterious effect on the integrity and enzymatic activity of virion-associated RT heterodimers, as well as the replication capacity of these resistant viruses.
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Antivirales/farmacología , VIH-1/efectos de los fármacos , Inhibidores de la Transcriptasa Inversa/farmacología , Replicación Viral/efectos de los fármacos , Western Blotting , Resistencia a Medicamentos , Transcriptasa Inversa del VIH , Humanos , ADN Polimerasa Dirigida por ARN/metabolismo , Relación Estructura-ActividadRESUMEN
Recently we demonstrated that the p58 subunit of p68/p58 HIV-2 reverse transcriptase (RT) heterodimer, produced by processing of p68/p68 homodimer with recombinant HIV-2 protease, terminates at Met484 [Fan, N., et al. (1995) J. Biol. Chem. 270, 13573-13579]. Here we describe purification and characterization of the p68/p58 heterodimer of recombinant HIV-2 RT. It exhibited both RT and RNase H activities, obeyed Michaelis-Menten kinetics, and was competitively inhibited by the DNA chain terminator ddTTP (Ki[app] = 305 +/- 20 nM). The HIV-2 RT-associated RNase H exhibited a marked preference for RNA hydrolysis from a HIV-1 gag-based heteropolymeric RNA/DNA hybrid in the presence of either Mg2+ or Mn2+, compared to the [3H]poly(rA).poly(dT) or [3H]poly(rG).poly(dC) homopolymeric substrates. Relative to HIV-1 RT, the RNase H activity of HIV-2 RT was only 5% toward the [3H]poly(rA).poly(dT) in the presence of Mg2+. The size distribution of products generated from [3H]poly(rA).poly(dT) by HIV-2 RT-associated RNase H was markedly distinct from that of HIV-1 RT in the presence of Mg2+ or Mn2+. The p68/p58 HIV-2 RT heterodimer, produced by specific cleavage using HIV-2 protease, should be useful for inhibition and biophysical studies aimed at discovering and designing drugs directed toward HIV-2.
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VIH-2/enzimología , ADN Polimerasa Dirigida por ARN/química , Ácido Aspártico Endopeptidasas/metabolismo , Secuencia de Bases , Cationes Bivalentes/farmacología , Cartilla de ADN/genética , ADN Viral/genética , Didesoxinucleótidos , Genes gag , Proteasa del VIH , Transcriptasa Inversa del VIH , VIH-2/genética , Humanos , Técnicas In Vitro , Cinética , Datos de Secuencia Molecular , Poli A/metabolismo , Poli T/metabolismo , Conformación Proteica , Procesamiento Proteico-Postraduccional , ADN Polimerasa Dirigida por ARN/genética , ADN Polimerasa Dirigida por ARN/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Inhibidores de la Transcriptasa Inversa/farmacología , Ribonucleasa H/metabolismo , Especificidad por Sustrato , Nucleótidos de Timina/farmacologíaRESUMEN
A quantitative human immunodeficiency virus type 1 (HIV-1) RNA polymerase chain reaction assay has been validated analytically and clinically in > 13,000 samples. The assay is highly reproducible with intra- and inter-assay precision of 16% and 19%, respectively. In 1,542 of 1,548 subjects with CD4+ counts of 0-500 cells per mm3, viral RNA levels were quantifiable and ranged from approximately 3,000-52,200,000 copies per milliliter. Median plasma HIV-1 RNA values were inversely proportional to CD4+ counts from 0-400 cells per mm3. When patients were off antiretroviral therapies for approximately 14 days prior to the initial baseline RNA PCR evaluation, the mean variance between the two baseline values was 23% (0.1 log). Of these patients, 95% had a sufficient plasma viral load to quantitate a 10-fold (1 log) diminution in viral load caused by antiviral therapy. In contrast, only 20% and 45% of these subjects had sufficient p24 and ICD p24 levels to detect a 50% diminution in circulating virus. The high precision and reproducibility of this quantitative RNA PCR assay provide an enhanced means of evaluating therapeutic drug regimens for HIV-1.
Asunto(s)
VIH-1/genética , Reacción en Cadena de la Polimerasa , ARN Viral/sangre , Secuencia de Bases , Proteína p24 del Núcleo del VIH/sangre , Humanos , Datos de Secuencia MolecularRESUMEN
Active, recombinant p68 reverse transcriptase (RT) from human immunodeficiency virus type 2 (HIV-2), with an NH2-terminal extension containing a hexahistidine sequence was isolated from extracts of Escherichia coli by immobilized metal affinity chromatography. Treatment of the purified p68/p68 homodimer of HIV-2 RT with recombinant HIV-2 protease generates stable, active heterodimer (p68/p58) that is resistant to further hydrolysis. Analysis of this p68/p58 HIV-2 RT heterodimer revealed that while one subunit is intact p68, the p58 subunit is COOH-terminally truncated by cleavage, not at Phe440 as is seen in processing of the p66/p66 HIV-1 RT homodimer by HIV-1 protease, but at Met484. The expected COOH-terminal p10 fragment resulting from hydrolysis of p68 at Met484 is not released intact, but undergoes further cleavage at Asn494, Met503, and Tyr532. Processing of p68/p68 HIV-2 RT with the HIV-1 protease led to cleavage of the Phe440-Tyr441 bond, exactly as is seen with p66/p66 HIV-1 RT, to give the analogous p53 subunit. Studies of a peptide substrate modeled after residues 437-444 in HIV-2 RT showed that while the HIV-1 protease was able to cleave the Phe440 bond, this bond was resistant to cleavage by the HIV-2 enzyme. Our findings provide a rationale for the previous observation that the RT heterodimer isolated from HIV-2 lysates is larger than that from HIV-1. We conclude that the p68/p58 HIV-2 RT heterodimer, containing the Met484 truncated p58 subunit, is a biologically relevant form of the enzyme in vivo.
Asunto(s)
Proteasa del VIH/metabolismo , VIH-1/enzimología , VIH-2/enzimología , ADN Polimerasa Dirigida por ARN/metabolismo , Secuencia de Aminoácidos , Clonación Molecular , Transcriptasa Inversa del VIH , Hidrólisis , Datos de Secuencia Molecular , Péptidos/metabolismo , Procesamiento Proteico-Postraduccional , ADN Polimerasa Dirigida por ARN/genética , Homología de Secuencia de Aminoácido , Especificidad por SustratoRESUMEN
Se describen dos casos de micosis de uñas y piel producidas por Nattrassia mangiferae en dos pacientes que nunca salieron de Brasil. El uso de medios de cicloheximida, la cual inhibe el desarrollo de este hongo, puede explicar porque él es infrecuentemente diagnosticado