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1.
Phys Rev Lett ; 132(12): 122701, 2024 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-38579210

RESUMO

^{140}Ce(n,γ) is a key reaction for slow neutron-capture (s-process) nucleosynthesis due to being a bottleneck in the reaction flow. For this reason, it was measured with high accuracy (uncertainty ≈5%) at the n_TOF facility, with an unprecedented combination of a high purity sample and low neutron-sensitivity detectors. The measured Maxwellian averaged cross section is up to 40% higher than previously accepted values. Stellar model calculations indicate a reduction around 20% of the s-process contribution to the Galactic cerium abundance and smaller sizeable differences for most of the heavier elements. No variations are found in the nucleosynthesis from massive stars.

2.
J Chromatogr A ; 1652: 462377, 2021 Aug 30.
Artigo em Inglês | MEDLINE | ID: mdl-34271255

RESUMO

Food testing is of great importance to the food industry and organizations to verify the authenticity claims, to prove the quality of raw materials and products, and to ensure food safety. The market prices of vanilla differed by a factor of about 20 in the last three decades. Therefore the risk of adulteration and counterfeiting of vanilla products is high. Instead of commonly used target analyses and sum parameter assays, a complementary non-target multi-imaging effect-directed screening was developed, which provided a new perspective on the wide range of vanilla product qualities on the market. Planar chromatography was combined with effect-directed assays, and the obtained biological and biochemical profiles of 32 vanilla products from nine different categories revealed a variety of active ingredients. Depending on the region, typical vanilla product profiles and activity patterns were obtained for pods, tinctures, paste (inner part), oleoresin and powders. However, some vanilla products showed additional active compounds and a different intensity pattern. The vanilla product profiles substantially differed from those of vanilla aroma or products containing synthetic vanillin or vanilla-flavored food products. Bioactive compounds of interest were online eluted and further characterized via HPTLC-HRMS, which allowed their tentative assignment. After purchase of the standards, these were successfully confirmed by co-chromatography. Quantification of vanillin across nine different product categories revealed levels ranging from 1 µg/g to 36 mg/g with a mean repeatability of 1.9%. The synthetic ethylvanillin was not detected in the investigated samples in significant concentrations. The assessment of differences in the activity patterns pointed to highly active compounds, which were not detected at UV/Vis/FLD but first via the biological and enzymatic assays. This effect-directed profiling bridges the gap from analytical food chemistry to food toxicology, and thus, makes an important contribution to consumer safety. In the same way, it would accelerate investigations for Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) according to Regulation (EC) No. 1907/2006.


Assuntos
Benzaldeídos/análise , Extratos Vegetais , Vanilla , Benzaldeídos/química , Cromatografia em Camada Fina , Extratos Vegetais/química , Extratos Vegetais/isolamento & purificação , Vanilla/química
3.
Phys Rev Lett ; 121(4): 042701, 2018 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-30095928

RESUMO

We report on the measurement of the ^{7}Be(n,p)^{7}Li cross section from thermal to approximately 325 keV neutron energy, performed in the high-flux experimental area (EAR2) of the n_TOF facility at CERN. This reaction plays a key role in the lithium yield of the big bang nucleosynthesis (BBN) for standard cosmology. The only two previous time-of-flight measurements performed on this reaction did not cover the energy window of interest for BBN, and they showed a large discrepancy between each other. The measurement was performed with a Si telescope and a high-purity sample produced by implantation of a ^{7}Be ion beam at the ISOLDE facility at CERN. While a significantly higher cross section is found at low energy, relative to current evaluations, in the region of BBN interest, the present results are consistent with the values inferred from the time-reversal ^{7}Li(p,n)^{7}Be reaction, thus yielding only a relatively minor improvement on the so-called cosmological lithium problem. The relevance of these results on the near-threshold neutron production in the p+^{7}Li reaction is also discussed.

4.
Target Oncol ; 11(2): 157-66, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26315966

RESUMO

BACKGROUND: Recently, in advanced non-small cell lung cancer (NSCLC), standard chemotherapy was flanked by biological agents directed against genomic abnormalities, including EGFR and ALK alterations, that significantly improved patient outcome. Despite these achievements, tumour progression almost always occurs and a reassessment of the tumour genetic profile may contribute to modulating the therapeutic regimen. Resampling may provide tissue for additional tests to detect acquired resistance and/or new genetic alterations, but the currently available information is limited. PATIENTS AND METHODS: Histological and genetic reassessments of biopsy or surgical tissue samples from 50 non-squamous NSCLC patients before and after at least one systemic treatment were performed. EGFR, KRAS, BRAF, PIK3CA and HER2 mutations were sequenced, p.T790M was identified with real-time PCR, and ALK and MET genomic alterations by fluorescence in situ hybridization. RESULTS: Overall in baseline biopsies, 37/50 (74 %) tumours had genetic alterations, either single (52 %) or multiple (22 %). Among them, 16 were EGFR mutations and 6 ALK rearrangements. In the second tissue sampling, 54 % of cases had additional genomic changes, including newly acquired alterations (81 %) or losses (18 %). The commonest changes were MET amplification and p.T790M mutation. One case had a histological shift from adenocarcinoma to small cell carcinoma. CONCLUSIONS: The remarkable number of molecular changes following systemic therapy and the genetic complexity of some cases underline the value of histological and molecular re-evaluation of lung cancer to tailor the most appropriate therapy during disease progression.


Assuntos
Carcinoma Pulmonar de Células não Pequenas/patologia , Carcinoma Pulmonar de Células não Pequenas/terapia , Neoplasias Pulmonares/patologia , Neoplasias Pulmonares/terapia , Adulto , Idoso , Biópsia , Quimioterapia Adjuvante , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Radioterapia Adjuvante , Estudos Retrospectivos
5.
Radiol Med ; 117(7): 1139-51, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22430677

RESUMO

PURPOSE: The aim of this study was to review some prognostic factors for survival after radiofrequency ablation (RFA) of metastases from colorectal cancer (CRC). MATERIALS AND METHODS: From 1996 to 2009, 262 patients with metastases from CRC were treated with RFA. Fourteen were lost to follow-up. The following predictors were analysed in the remaining 248: synchronous/metachronous metastases, single/multiple metastases, diameter of largest metastasis and absence/presence of extrahepatic metastases. Survival was measured from the date of metastasis diagnosis and from the date of RFA. RESULTS: Survival at 1, 2, 3 and 5 years was 93%, 78%, 62% and 35% from metastasis diagnosis, and 84%, 59%, 43% and 23% from the date of RFA. Median survival was 41 months in patients with largest metastasis ≤3 cm and 21.7 months for those with metastases >3 cm (p=0.0001); survival increased to 45.2 months in patients with largest metastasis ≤2.5 cm and fell to 18.5 months in those with metastasis >3.5 cm. Median survival of patients with extrahepatic metastases was significantly lower than that of patients without extrahepatic disease (23.3 vs. 32.6 months, p=0.018). CONCLUSIONS: In light of our long-term results obtained with commonly used equipment, small lesion size (diameter of largest lesion ≤3 or 2.5 cm) proved to be the most favourable prognostic factor for survival in patients with CRC metastases to the liver treated with RFA. This conclusion is probably related to the possibility of obtaining radical ablation and points to the usefulness of devices allowing ablation of larger volumes. In the presence of extrahepatic metastases, RFA has less impact on survival, even though it is potentially useful in patients at a higher risk of death due to hepatic rather than extrahepatic metastases.


Assuntos
Ablação por Cateter/métodos , Neoplasias Colorretais/patologia , Neoplasias Hepáticas/secundário , Neoplasias Hepáticas/cirurgia , Adulto , Idoso , Idoso de 80 Anos ou mais , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Distribuição de Qui-Quadrado , Neoplasias Colorretais/tratamento farmacológico , Feminino , Hepatectomia , Humanos , Neoplasias Hepáticas/tratamento farmacológico , Masculino , Pessoa de Meia-Idade , Prognóstico , Taxa de Sobrevida , Resultado do Tratamento
6.
Radiol Med ; 117(3): 378-92, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-22095414

RESUMO

PURPOSE: Microwave thermal ablation (MWA) opens up a new scenario in the field of image-guided tumour ablation thanks to its potential advantages over validated radiofrequency ablation (RFA). In this pilot study, we assessed the technical success, safety and efficacy of MWA in treating hepatic malignancies. MATERIALS AND METHODS: After obtaining informed consent, we enrolled 15 inoperable patients, for a total of 19 lesions (ten metastases, nine hepatocellular carcinoma) with a mean diameter of 47 mm (range 14-78 mm). Mean follow-up was 8 (range 1-14) months. RESULTS: Technical success reached 100%. Complications (one major and one minor) occurred in two cases. Complete ablation, obtained in 68.4% of cases, showed no significant correlation with either cancer histological type or with lesion diameter. At follow-up, treatment failures occurred in 60% of cases; lesion diameter was the only prognostic factor for maintaining complete ablation. CONCLUSIONS: Our preliminary results should encourage further trials of this technique. MWA proved to be feasible and safe in treating advanced-stage liver tumours and represented an additional therapeutic attempt to be validated in further and larger efficacy studies.


Assuntos
Ablação por Cateter/métodos , Neoplasias Hepáticas/cirurgia , Micro-Ondas/uso terapêutico , Carcinoma Hepatocelular/cirurgia , Seguimentos , Humanos , Neoplasias Hepáticas/secundário , Projetos Piloto , Resultado do Tratamento
8.
Radiol Med ; 114(6): 871-89, 2009 Sep.
Artigo em Inglês, Italiano | MEDLINE | ID: mdl-19484354

RESUMO

The role of computed tomography (CT) in the diagnosis of the solitary pulmonary nodule (SPN) is constantly expanding. CT helps to detect a growing number of increasingly small lesions, but, as with chest radiography, the primary goal in the evaluation of small pulmonary nodules is to exclude malignancy. Despite the availability of numerous, variously invasive, diagnostic tests, diagnostic accuracy tends to decline as the size of the nodule decreases. The role of the radiologist is therefore to help the clinician determine the most appropriate management strategy by using all available modalities [CT, magnetic resonance (MR) imaging, positron emission tomography (PET)] and evaluating the patient's clinical history and the imaging features leading to a diagnosis of benignity or malignancy. Imaging features include nodule size, margins, calcifications and fatty component, internal features (cavitations, pseudocavitations, air bronchogram, halo sign), as well as advanced techniques for characterisation (growth rate, contrast enhancement) and management (computer-aided diagnosis, Bayesian analysis, neural networks). The aim of this paper is to summarise the approach to pulmonary nodules from the point of view of the radiologist, oncologist and thoracic surgeon.


Assuntos
Diagnóstico por Imagem , Neoplasias Pulmonares/diagnóstico , Nódulo Pulmonar Solitário/diagnóstico , Meios de Contraste , Humanos , Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Tomografia Computadorizada de Emissão/métodos , Tomografia Computadorizada por Raios X
9.
Radiol Med ; 111(4): 516-25, 2006 Jun.
Artigo em Inglês, Italiano | MEDLINE | ID: mdl-16779538

RESUMO

PURPOSE: The purpose of this study was to show the effectiveness of ultrasound (US) in the evaluation of pneumothorax by comparison with X-rays and computed tomography (CT). MATERIALS AND METHODS: A series of 184 patients (130 men and 54 women), aged 26 to 82 years, underwent chest US after percutaneous needle biopsy. US findings were compared with CT postbiopsy selective slices and to X-rays. RESULTS: Pneumothorax was identified in 46 patients (25%) by CT, in 44 by US, with no false positives, and in 19 by X-rays. US sensitivity was 95.65%, specificity 100% and diagnostic effectiveness 98.91%. CONCLUSIONS: Chest US was found to be a valuable diagnostic tool in pneumothorax diagnosis, with diagnostic effectiveness well beyond X-rays and similar to CT.


Assuntos
Pneumotórax/diagnóstico por imagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Algoritmos , Biópsia por Agulha , Diagnóstico Diferencial , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Sensibilidade e Especificidade , Tomografia Computadorizada por Raios X , Ultrassonografia
10.
J Chem Phys ; 122(9): 094113, 2005 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-15836118

RESUMO

Rigorous methods for the post-HF (HF-Hartree-Fock) determination of correlation corrections for crystalline solids are currently being developed following different strategies. The CRYSTAL program developed in Torino and Daresbury provides accurate HF solutions for periodic systems in a basis set of Gaussian type functions; for insulators, the occupied HF manifold can be represented as an antisymmetrized product of well localized Wannier functions. This makes possible the extension to nonconducting crystals of local correlation linear scaling On techniques as successfully and efficiently implemented in Stuttgart's MOLPRO program. These methods exploit the fact that dynamic electron correlation effects between remote parts of a molecule (manifesting as dispersive interactions in intermolecular perturbation theory) decay as an inverse sixth power of the distance R between these fragments, that is, much more quickly than the Coulomb interactions that are treated already at the HF level. Translational symmetry then permits the crystalline problem to be reduced to one concerning a cluster around the reference zero cell. A periodic local correlation program (CRYSCOR) has been prepared along these lines, limited for the moment to the solution of second-order Moller-Plesset equations. Exploitation of point group symmetry is shown to be more important and useful than in the molecular case. The computational strategy adopted and preliminary results concerning five semiconductors with tetrahedral structure (C, Si, SiC, BN, and BeS) are presented and discussed.

11.
J Am Acad Dermatol ; 40(2 Pt 2): 315-7, 1999 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10025857

RESUMO

Bednar tumor is a rare pigmented variant of dermatofibrosarcoma protuberans (DFSP). Because of its rarity, information is lacking regarding the optimal therapy and potential utility of immunohistochemistry in diagnosis. We report a case of Bednar tumor in which the diagnosis was aided by immunohistochemistry for CD34, an antigen known to be expressed in DFSP but not previously reported in Bednar tumor. Our case was also striking because it represents the first reported appearance of a Bednar tumor at a site of prior immunization, a phenomenon previously noted in some cases of DFSP. The patient was treated effectively with Mohs surgery and is without recurrence at 9 months.


Assuntos
Antígenos CD34/análise , Biomarcadores Tumorais/análise , Dermatofibrossarcoma/imunologia , Neoplasias Cutâneas/imunologia , Vacinação/efeitos adversos , Adulto , Dermatofibrossarcoma/patologia , Dermatofibrossarcoma/cirurgia , Feminino , Humanos , Cirurgia de Mohs , Pele/imunologia , Pele/patologia , Neoplasias Cutâneas/patologia , Neoplasias Cutâneas/cirurgia
12.
Acta Odontol Latinoam ; 10(2): 71-9, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-11885240

RESUMO

We here in determined the histochemical and immunological changes that salivary glands experience as a result of the ageing process. Samples from the inferior lip of children, youngsters and young adults were analyzed by histochemical techniques, Periodic-acid-Schiff, (PAS) Alcian blue (AB) (pHs 1.0 and 2.5) and Toluidine blue for mucosubstances and immunohistochemical staining of S 100 protein and cytokeratin 20, avidin-biotin system (DAB). In children, the techniques used evidenced various reaction degrees in the acinar cells, even within a single acinous. They displayed a slight metachromasia and were alcianophilic at pH 2.5. In youngsters, and especially in adults, glands showed a notable PAS positivity and alcianophilia at both pH levels, and an intense metachromasia. PS 100 was positive in the basal area of the acini and serous demilunes of all groups, the reactivity being higher in adults. Cytokeratin 20 was better observed in ductal cells from children glands. These findings suggest modifications at cytological level and in the chemical composition of the secretory granules, indicating possible functional variations in lip salivary glands related to the ageing process.


Assuntos
Envelhecimento/fisiologia , Glândulas Salivares Menores/química , Glândulas Salivares Menores/citologia , Adolescente , Adulto , Anticorpos Monoclonais , Criança , Histocitoquímica , Humanos , Queratinas/análise , Lábio , Proteínas S100/análise , Vesículas Secretórias
13.
Cutis ; 60(6): 289-90, 1997 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-9426968

RESUMO

We report a case of vitiligo that occurred during the second month of interferon alpha 2a therapy for chronic active hepatitis C. The patient received the interferon for four months.


Assuntos
Antivirais/efeitos adversos , Hepatite C Crônica/tratamento farmacológico , Interferon-alfa/efeitos adversos , Vitiligo/induzido quimicamente , Antivirais/uso terapêutico , Humanos , Interferon alfa-2 , Interferon-alfa/uso terapêutico , Masculino , Pessoa de Meia-Idade , Proteínas Recombinantes
14.
Biochem Pharmacol ; 51(6): 743-50, 1996 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-8602869

RESUMO

U-31,355, or 4-amino-2-(benzylthio)-6-chloropyrimidine is an inhibitor of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) and possesses anti-HIV activity in HIV-1-infected lymphocytes grown in tissue culture. The compound acts as a specific inhibitor of the RNA-directed DNA polymerase function of HIV-1RT and does not impair the functions of the DNA-catalyzed DNA polymerase or the Rnase H of the enzyme. Kinetic studies were carried out to elucidate the mechanism of RT inhibition by U-31,355. The data were analyzed using Briggs-Haldane kinetics, assuming that the reaction is ordered in that the template:primer binds to the enzyme first, followed by the addition of dNTP, and that the polymerase is a processive enzyme. Based on these assumptions, a velocity equation was derived that allows the calculation of all the essential forward and backward rate constants for the reactions occurring between the enzyme, its substrates, and the inhibitor. The results obtained indicate that U-31,355 acts as a mixed inhibitor with respect to the template:primer and dNTP binding sites associated with the RNA-directed DNA polymerase domain of the enzyme. The inhibitor possessed a significantly higher binding affinity for the enzyme-substrate complexes, than for the free enzyme and consequently did not directly affect the functions of the substrate binding sites. Therefore, U-31,355 appears to impair an event occurring after the formation of the enzyme-substrate complexes, which involves either inhibition of the phosphoester bond formation or translocation of the enzyme relative to its template:primer following the formation of the ester bond. Moreover, the potency of U-31,355 depends on the base composition of the template:primer in that the inhibitor showed a much higher binding affinity for the enzyme-poly (rC):(dG)10 complexes than for the poly (rA):(dT)10 complexes.


Assuntos
Antivirais/farmacologia , Inibidores Enzimáticos/farmacologia , Inibidores da Transcriptase Reversa/metabolismo , Animais , Infecções por HIV/tratamento farmacológico , Infecções por HIV/enzimologia , Transcriptase Reversa do HIV , HIV-1/efeitos dos fármacos , HIV-1/enzimologia , Humanos , Cinética , Linfócitos/virologia , Computação Matemática , Camundongos , Pirimidinas/farmacologia , DNA Polimerase Dirigida por RNA/metabolismo , Retroviridae/enzimologia , Ribonuclease H/antagonistas & inibidores , Ribonuclease H/metabolismo , Proteínas Virais/antagonistas & inibidores , Proteínas Virais/metabolismo
16.
J Med Chem ; 37(7): 999-1014, 1994 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-7512142

RESUMO

A variety of analogues of 1-[4-methoxy-3,5-dimethylbenzyl]-4-[3-(ethylamino)-2-pyridyl]piperazine hydrochloride (U-80493E) were synthesized and evaluated for their inhibition of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT). Replacement of the substituted aryl moiety with various substituted indoles provided bis(heteroaryl)piperazines (BHAPs) that were 10-100-fold more potent than U-80493E. The pyridyl portion of the lead molecule was found to be very sensitive to modifications. Extensive preclinical evaluations of several of these compounds led to the selection of 1-[(5-methoxyindol-2-yl)carbonyl]-4-[3-(ethylamino)-2- pyridyl]piperazine methanesulfonate (U-87201E, atevirdine mesylate) for clinical evaluation.


Assuntos
Antivirais/síntese química , HIV-1/enzimologia , Piperazinas/síntese química , Inibidores da Transcriptase Reversa , Aminopiridinas/química , Aminopiridinas/farmacologia , Antivirais/farmacologia , Células Cultivadas , Transcriptase Reversa do HIV , Humanos , Estrutura Molecular , Piperazinas/química , Piperazinas/farmacologia
17.
J Virol Methods ; 47(1-2): 129-39, 1994 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-7519626

RESUMO

To study the functional properties of HIV-1 reverse transcriptase (RT) from intact viral particles without the requirement for tissue culture expansion, a method that couples HIV-1 reverse transcription utilizing its endogenous RT (ERT) with polymerase chain reaction amplification (PCR) was developed. Detection of endogenous reverse transcripts from HIV particles by ERT-PCR was compared to HIV RNA PCR detection using avian myeloblastosis virus (AMV) RT from plasma samples from 45 HIV-1 infected patients. The HIV ERT-PCR method was capable of detecting plasma viremia with the same efficiency (29/29 patients) as the AMV RT HIV RNA PCR in patients with CD4 cell counts of less than 500/mm3. The determination of HIV-RT drug sensitivities using four well-characterized HIV-1 lab strains was assessed. The ERT-PCR method detected reduced sensitivity to TIBO R82150 (10 microM) in a TIBO resistant strain but not in the TIBO sensitive HTLV-IIIB viral mixture or an HTLV-IIIB clone. In summary, the HIV ERT-PCR method provides a useful approach for the detection of HIV and the characterization of RT sensitivities among HIV-1 strains.


Assuntos
HIV-1/isolamento & purificação , Reação em Cadeia da Polimerase/métodos , DNA Polimerase Dirigida por RNA/sangue , Antivirais/farmacologia , Benzodiazepinas/farmacologia , DNA Viral/genética , Didesoxinucleotídeos , Resistência Microbiana a Medicamentos , Transcriptase Reversa do HIV , HIV-1/enzimologia , Humanos , Imidazóis/farmacologia , DNA Polimerase Dirigida por RNA/genética , Inibidores da Transcriptase Reversa , Sensibilidade e Especificidade , Nucleotídeos de Timina/farmacologia , Zidovudina/análogos & derivados , Zidovudina/farmacologia
19.
J Biol Chem ; 268(20): 14875-80, 1993 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-7686907

RESUMO

The quinoline U-78036 represents a new class of non-nucleoside human immunodeficiency virus (HIV)-1 reverse transcriptase inhibitors. The agent possesses excellent antiviral activity at nontoxic doses in HIV-1-infected lymphocytes grown in tissue culture. Enzymatic kinetic studies of the HIV-1 reverse transcriptase (RT)-catalyzed RNA-directed DNA polymerase function were carried out in order to determine whether the inhibitor interacts with the template-primer or deoxyribonucleotide triphosphate (dNTP) binding sites of the polymerase. The data were analyzed using steady-state or Briggs-Haldane kinetics assuming that the template-primer binds to the enzyme first followed by the dNTP and that the polymerase functions processively. The calculated rate constants are in agreement with this model. The results show that the inhibitor acts as a mixed to noncompetitive inhibitor with respect to both the template-primer and the dNTP binding sites of the enzyme. Hence, U-78036 inhibits the RNA-directed DNA polymerase activity of RT by interacting with a site distinct from the template-primer and dNTP binding sites. Moreover, the potency of U-78036 is dependent on the base composition of the template-primer. The equilibrium constants for various enzyme-substrate-inhibitor complexes were at least seven times lower for the poly(rC).(dG)10-catalyzed system than the one catalyzed by poly(rA).(dT)10. In addition, the inhibitor does not impair the DNA-dependent DNA polymerase activity and the RNase H function of HIV-1 RT nor does it inhibit the RNA-directed DNA polymerase activity of the HIV-2, avian myoblastoma virus, and murine leukemia virus RT enzymes.


Assuntos
Antivirais/farmacologia , HIV-1/efeitos dos fármacos , Nitrilas/farmacologia , Quinolinas/farmacologia , Inibidores da Transcriptase Reversa , Células Cultivadas , Transcriptase Reversa do HIV , HIV-1/enzimologia , Cinética , Linfócitos/microbiologia , Estrutura Molecular , Nitrilas/química , Quinolinas/química , DNA Polimerase Dirigida por RNA/metabolismo , Retroviridae/enzimologia , Ribonuclease H/antagonistas & inibidores , Especificidade por Substrato , Moldes Genéticos
20.
Antimicrob Agents Chemother ; 37(5): 1127-31, 1993 May.
Artigo em Inglês | MEDLINE | ID: mdl-7685995

RESUMO

Bisheteroarylpiperazines are potent inhibitors of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT). We describe a novel bisheteroarylpiperazine, U-90152 [1-(5-methanesulfonamido-1H-indol-2-yl-carbonyl)-4-[3-(1-methyl eth yl-amino)pyridinyl]piperazine], which inhibited recombinant HIV-1 RT at a 50% inhibitory concentration (IC50) of 0.26 microM (compared with IC50s of > 440 microM for DNA polymerases alpha and delta). U-90152 blocked the replication in peripheral blood lymphocytes of 25 primary HIV-1 isolates, including variants that were highly resistant to 3'-azido-2',3'-dideoxythymidine (AZT) or 2',3'-dideoxyinosine, with a mean 50% effective dose of 0.066 +/- 0.137 microM. U-90152 had low cellular cytotoxicity, causing less than 8% reduction in peripheral blood lymphocyte viability at 100 microM. In experiments assessing inhibition of the spread of HIV-1IIIB in cell cultures, U-90152 was much more effective than AZT. When approximately 500 HIV-1IIIB-infected MT-4 cells were mixed 1:1,000 with uninfected cells, 3 microM AZT delayed the evidence of rapid viral growth for 7 days. In contrast, 3 microM U-90152 totally prevented the spread of HIV-1, and death and/or dilution of the original inoculum of infected cells prevented renewed viral growth after U-90152 was removed at day 24. The combination of U-90152 and AZT, each at 0.5 microM, also totally prevented viral spread. Finally, although the RT amino acid substitutions K103N (lysine 103 to asparagine) and Y181C (tyrosine 181 to cysteine), which confer cross-resistance to several nonnucleoside inhibitors, also decrease the potency of U-90152, this drug retains significant activity against these mutant RTs in vitro (IC50s, approximately 8 microgramM).


Assuntos
Antivirais/farmacologia , HIV-1/efeitos dos fármacos , Indóis/farmacologia , Piperazinas/farmacologia , Replicação Viral/efeitos dos fármacos , Linhagem Celular , Delavirdina , Resistência Microbiana a Medicamentos , Infecções por HIV/tratamento farmacológico , Infecções por HIV/microbiologia , Transcriptase Reversa do HIV , HIV-1/enzimologia , HIV-1/fisiologia , Humanos , Testes de Sensibilidade Microbiana , DNA Polimerase Dirigida por RNA/genética , Inibidores da Transcriptase Reversa , Linfócitos T/efeitos dos fármacos , Linfócitos T/microbiologia
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