RESUMEN
Despite ongoing research and recent discoveries, there remains a paucity of data regarding COVID-19 and its implications for pregnant women, particularly its effects on the developing fetus. To date, there are a limited number of articles available regarding the utility of Extra Corporeal Membrane Oxygenation (ECMO) for cardio-respiratory support of pregnant women during the perinatal period. Additionally, there are only a few case reports detailing the delivery management of a baby born to a mother on ECMO support. Here, we report a case of a premature, low birth weight neonate delivered by a 32-year-old woman while on ECMO due to severe acute respiratory distress syndrome resulting from COVID-19 infection.
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COVID-19 , Oxigenación por Membrana Extracorpórea , Complicaciones Infecciosas del Embarazo , Adulto , COVID-19/terapia , Femenino , Humanos , Recién Nacido , Madres , Embarazo , Complicaciones Infecciosas del Embarazo/terapia , SARS-CoV-2RESUMEN
One of Saturn's largest moons, Enceladus, possesses a vast extraterrestrial ocean (i.e., exo-ocean) that is increasingly becoming the hotspot of future research initiatives dedicated to the exploration of putative life. Here, a new bio-exploration concept design for Enceladus' exo-ocean is proposed, focusing on the potential presence of organisms across a wide range of sizes (i.e., from uni- to multicellular and animal-like), according to state-of-the-art sensor and robotic platform technologies used in terrestrial deep-sea research. In particular, we focus on combined direct and indirect life-detection capabilities, based on optoacoustic imaging and passive acoustics, as well as molecular approaches. Such biologically oriented sampling can be accompanied by concomitant geochemical and oceanographic measurements to provide data relevant to exo-ocean exploration and understanding. Finally, we describe how this multidisciplinary monitoring approach is currently enabled in terrestrial oceans through cabled (fixed) observatories and their related mobile multiparametric platforms (i.e., Autonomous Underwater and Remotely Operated Vehicles, as well as crawlers, rovers, and biomimetic robots) and how their modified design can be used for exo-ocean exploration.
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Exobiología/instrumentación , Medio Ambiente Extraterrestre , Técnicas Fotoacústicas/instrumentación , Saturno , Diseño de Equipo , Exobiología/métodos , Océanos y Mares , Robótica/instrumentaciónRESUMEN
To conduct surveillance and determine the safety profile of new hepatitis C virus treatments in real-world clinical practice. Hepatic decompensation and other serious adverse events were investigated in an observational cohort study of 511 patients treated with regimens containing sofosbuvir, December 2013-June 2014. Among 499 previously stable patients (no history of hepatic decompensation during the previous 12 months), a nested case-control study was performed to identify predictors of decompensation/serious adverse event. Cases and controls were matched 1:5 based on treatment regimen and duration. Matched conditional logistic regression was used for analysis. Providers scored the likelihood that events were treatment-related (scale = 0-4). The cumulative incidence of decompensation/events was 6.4% for the total cohort. Among 499 previously stable patients, the incidence of decompensation/events was 4.5%; the mortality rate was 0.6%. Sixteen of the 499 experienced one or more serious complications considered to be at least potentially treatment-related, and the sustained virological response rate was 7/16 (44%). Two cases, both on sofosbuvir/simeprevir (without interferon or ribavirin), had complications consistent with autoimmune events (score 3, 'likely treatment-related'), and one experienced a flare of autoimmune hepatitis. Compared to controls, cases had higher baseline median model for end-stage liver disease scores (14 vs 8, P < 0.01). Decompensation/events was independently associated with lower baseline albumin (OR = 0.12/g/dL, P = 0.01) and higher total bilirubin (OR = 4.31/mg/dL, P = 0.01). Reduced hepatic function at baseline increased the risk of liver decompensation/events.
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Antivirales/uso terapéutico , Bilirrubina/sangre , Insuficiencia Hepática/epidemiología , Hepatitis C Crónica/complicaciones , Hepatitis C Crónica/tratamiento farmacológico , Albúmina Sérica/análisis , Sofosbuvir/uso terapéutico , Anciano , Estudios de Casos y Controles , Técnicas de Apoyo para la Decisión , Femenino , Hepatitis C Crónica/patología , Humanos , Incidencia , Masculino , Persona de Mediana Edad , Pronóstico , Albúmina Sérica Humana , Simeprevir/uso terapéutico , Análisis de SupervivenciaRESUMEN
Chronic hepatitis C virus (HCV) infection may cause kidney injury, particularly in the setting of cryoglobulinemia or cirrhosis; however, few studies have evaluated the epidemiology of acute kidney injury in patients with HCV. We aimed to describe national temporal trends of incidence and impact of severe acute kidney injury (AKI) requiring renal replacement 'dialysis-requiring AKI' in hospitalized adults with HCV. We extracted our study cohort from the Nationwide Inpatient Sample of the Healthcare Cost and Utilization Project using data from 2004 to 2012. We defined HCV and dialysis-requiring acute kidney injury based on previously validated ICD-9-CM codes. We analysed temporal changes in the proportion of hospitalizations complicated by dialysis-requiring AKI and utilized survey multivariable logistic regression models to estimate its impact on in-hospital mortality. We identified a total of 4,603,718 adult hospitalizations with an associated diagnosis of HCV from 2004 to 2012, of which 51,434 (1.12%) were complicated by dialysis-requiring acute kidney injury. The proportion of hospitalizations complicated by dialysis-requiring acute kidney injury increased significantly from 0.86% in 2004 to 1.28% in 2012. In-hospital mortality was significantly higher in hospitalizations complicated by dialysis-requiring acute kidney injury vs those without (27.38% vs 2.95%; adjusted odds ratio: 2.09; 95% confidence interval: 1.74-2.51). The proportion of HCV hospitalizations complicated by dialysis-requiring acute kidney injury increased significantly between 2004 and 2012. Similar to observations in the general population, dialysis-requiring acute kidney injury was associated with a twofold increase in odds of in-hospital mortality in adults with HCV. These results highlight the burden of acute kidney injury in hospitalized adults with HCV infection.
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Lesión Renal Aguda/terapia , Hepatitis C Crónica/virología , Hospitalización/estadística & datos numéricos , Diálisis Renal/estadística & datos numéricos , Adolescente , Adulto , Anciano , Niño , Preescolar , Estudios de Cohortes , Comorbilidad , Femenino , Hepacivirus/aislamiento & purificación , Mortalidad Hospitalaria , Humanos , Lactante , Recién Nacido , Pacientes Internos/estadística & datos numéricos , Masculino , Persona de Mediana Edad , Oportunidad Relativa , Índice de Severidad de la Enfermedad , Estados Unidos , Adulto JovenRESUMEN
BACKGROUND: Liver transplantation (LT) is a treatment option for select human immunodeficiency virus (HIV)-infected patients with advanced liver disease. The aim of this study was to describe LT evaluation outcomes in HIV-infected patients. METHODS: All HIV-infected patients referred for their first LT evaluation at the Mount Sinai Medical Center were included in this retrospective, descriptive cohort study. Multivariable logistic regression was used to identify factors independently associated with listing. RESULTS: Between February 2000 and April 2012, 366 patients were evaluated for LT, with 66 (18.0%) listed for LT and 300 (82.0%) not listed. Fifty-one patients (13.9%) died before completing evaluation and 85 (23.2%) were too early for listing. Reasons patients were declined for listing were psychosocial (15.8%), HIV-related (10.4%), loss to follow-up (9.6%), surgical/medical (6.0%), liver-related (4.4%), patient choice (3.4%), and financial (1.6%). Listed patients were more likely to have hepatocellular carcinoma (HCC) (43.1% vs. 17.1%; P < 0.0001) and less likely to have hepatitis B (6.2% vs. 15.7%; P = 0.04) or a psychiatric history (19.7% vs. 35.2%; P = 0.02) than those not listed. In multivariable analysis, HCC (odds ratio [OR] 5.79; 95% confidence interval [95% CI]: 2.97-11.28), model for end-stage liver disease (MELD) score at referral (OR 1.06; 95% CI 1.01-1.11), and hepatitis B (OR 0.26; 95% CI 0.08-0.79) were associated with listing. CONCLUSION: MELD score and HCC were positive predictors of listing in HIV-infected patients referred for LT evaluation and, therefore, timely referrals are vital in these patients. As MELD is a predictor for death while undergoing evaluation, rapid evaluation should be performed in HIV-infected patients with a higher MELD score.
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Enfermedad Hepática en Estado Terminal/cirugía , Infecciones por VIH/complicaciones , Trasplante de Hígado , Selección de Paciente , Listas de Espera , Adulto , Anciano , Enfermedad Hepática en Estado Terminal/complicaciones , Enfermedad Hepática en Estado Terminal/diagnóstico , Enfermedad Hepática en Estado Terminal/mortalidad , Femenino , Infecciones por VIH/mortalidad , Humanos , Modelos Logísticos , Masculino , Persona de Mediana Edad , Análisis Multivariante , Derivación y Consulta , Estudios Retrospectivos , Índice de Severidad de la Enfermedad , Listas de Espera/mortalidadAsunto(s)
Antivirales/efectos adversos , Hepatitis C Crónica/tratamiento farmacológico , Interferón-alfa/efectos adversos , Cirrosis Hepática/tratamiento farmacológico , Oligopéptidos/efectos adversos , Polietilenglicoles/efectos adversos , Ribavirina/efectos adversos , Femenino , Humanos , MasculinoRESUMEN
BACKGROUND: Data about adverse events are needed to optimise telaprevir-based therapy in a broad spectrum of patients. AIM: To investigate adverse events of telaprevir-based therapy in patients with and without advanced fibrosis or cirrhosis in a real-world setting. METHODS: Data on 174 hepatitis C-infected patients initiating telaprevir-based therapy at Mount Sinai and Montefiore medical centres were collected. Biopsy data and FIB-4 scores identified patients with advanced fibrosis. Multivariable fully adjusted models were built to assess the effect of advanced fibrosis on specific adverse events and discontinuation of treatment due to an adverse event. RESULTS: Patients with (n = 71) and without (n = 103) advanced fibrosis were similar in BMI, ribavirin exposure, gender, prior treatment history, haemoglobin and creatinine, but differed in race. Overall, 47% of patients completed treatment and 40% of patients achieved SVR. Treated patients with and without advanced fibrosis or cirrhosis had similar rates of adverse events; advanced fibrosis, however, was independently associated with ano-rectal discomfort (P = 0.03). Three patients decompensated and had advanced fibrosis. The discontinuation of all treatment medications due to an adverse event was significantly associated with older age (P = 0.01), female gender (P = 0.01) and lower platelets (P = 0.03). CONCLUSIONS: Adverse events were common, but were not significantly related to the presence of advanced fibrosis or cirrhosis. More critical monitoring in older and female patients with low platelets throughout treatment may reduce adverse event-related discontinuations.
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Antivirales/efectos adversos , Hepatitis C Crónica/tratamiento farmacológico , Interferón-alfa/efectos adversos , Cirrosis Hepática/tratamiento farmacológico , Oligopéptidos/efectos adversos , Polietilenglicoles/efectos adversos , Ribavirina/efectos adversos , Anemia/inducido químicamente , Antivirales/uso terapéutico , Quimioterapia Combinada , Femenino , Hepatitis C Crónica/sangre , Humanos , Interferón alfa-2 , Interferón-alfa/uso terapéutico , Cirrosis Hepática/sangre , Masculino , Persona de Mediana Edad , Oligopéptidos/uso terapéutico , Recuento de Plaquetas , Polietilenglicoles/uso terapéutico , Proteínas Recombinantes/efectos adversos , Proteínas Recombinantes/uso terapéutico , Ribavirina/uso terapéuticoRESUMEN
Oral chemotherapy agents provide patients with choice and home-based therapy but demand greater emphasis on patient support and education to minimise toxicities. To meet this demand, a nurse-/pharmacy-led clinic was established at the Beatson Oncology Centre in 2003 for the provision of oral capecitabine to metastatic colorectal cancer patients to provide a controlled and supportive environment. We conducted a prospective audit of 52 patients attending the clinic from March 2003 to June 2004 and a retrospective survey of patient experiences to assess clinic effectiveness. Of 52 patients, 79% completed at least 3 cycles of treatment (mean 3.5). Capecitabine was well tolerated. The dose was reduced on at least one occasion in 15 (29%) patients and 17 (30%) patients experienced at least one delay. Patient satisfaction, indicated by questionnaire responses (n=27), was high. Most patients (> or =85%) thought that the service provision was useful and well organised. The results indicate that a nurse-/pharmacy-led clinic for the provision of home-based oral capecitabine is safe, effective and acceptable to most patients. The success of this clinic can provide a model for use in other centres and in other types of cancer, such as breast cancer, where oral chemotherapy is a treatment option.
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Antimetabolitos Antineoplásicos/uso terapéutico , Neoplasias Colorrectales/tratamiento farmacológico , Desoxicitidina/análogos & derivados , Fluorouracilo/análogos & derivados , Servicio Ambulatorio en Hospital/organización & administración , Satisfacción del Paciente , Servicio de Farmacia en Hospital/organización & administración , Administración Oral , Anciano , Anciano de 80 o más Años , Instituciones Oncológicas , Capecitabina , Neoplasias Colorrectales/enfermería , Neoplasias Colorrectales/psicología , Desoxicitidina/uso terapéutico , Monitoreo de Drogas , Femenino , Fluorouracilo/uso terapéutico , Servicios de Atención a Domicilio Provisto por Hospital/organización & administración , Humanos , Liderazgo , Masculino , Persona de Mediana Edad , Rol de la Enfermera , Auditoría de Enfermería , Investigación en Evaluación de Enfermería , Evaluación de Programas y Proyectos de Salud , Estudios Prospectivos , Estudios Retrospectivos , Escocia , Encuestas y CuestionariosRESUMEN
Gene expression profiling allows the level of activity of thousands of genes to be monitored simultaneously. Profiling is often carried out on specialized chips or slides, which have microarrays of gene targets at predetermined addresses. In the immediate future, microarrays promise to yield new insights into hepatitis C virus (HCV) pathogenesis and to produce 'signatures' that can be used in molecular diagnostics. In the longer-term, they may aid the development of serological tests by identifying genes encoding secretory proteins produced by HCV-infected livers, and they may suggest new avenues for disease intervention by detecting genes whose products are retained in the infected liver.
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Perfilación de la Expresión Génica , Hepatitis C/genética , Análisis de Secuencia por Matrices de Oligonucleótidos , Hepatitis C/diagnóstico , Hepatitis C/terapia , Hepatitis C/virología , Humanos , Hígado/metabolismoRESUMEN
Prohibitin is an evolutionary conserved protein that is associated with cellular differentiation, atresia, and luteolysis in the rat ovary. However, the specific cellular location and function of prohibitin in ovarian cells has not been clearly elucidated. To characterize the expression of prohibitin during cell proliferation, differentiation, and cell death, we have successfully established a temperature-sensitive granulosa cell line, designated RGA-1. At a permissive temperature of 33 C, RGA-1 cells proliferate, but revert to a differentiated phenotype at a nonpermissive temperature of 39 C. Significant inductions of prohibitin mRNA and protein expression were observed in the differentiated phenotype when compared with proliferating cells. Differentiated RGA-1 cells were found to express inhibin alpha- and beta-transcripts, as well as steroidogenic acute regulatory protein and peripheral-type benzodiazepine receptor proteins in a manner reminiscent of steroidogenic functional responses observed in primary differentiated granulosa cells. Prohibitin expression correlated well with the expression of these steroidogenic proteins. At 39 C, RGA-1 cells also displayed increases in p53 protein levels, indicative of growth arrest in the nonproliferating cells. Confocal and electron microscopic examinations revealed increased prohibitin localization to the mitochondria at 39 C, along with changes in mitochondrial size and shape. These changes were accompanied by marked reductions in cytochrome c oxidase subunit II levels and in unit mitochondrial transmembrane potential. In addition, cell fractionation studies demonstrated that the prohibitin protein was mainly localized to the mitochondrial membrane. Collectively, these findings suggest a role for prohibitin in mitochondrial structure and function during growth and differentiation in ovarian granulosa cells. Prohibitin expression may also be indicative of mitochondrial destabilization during apoptosis-related events.
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Células de la Granulosa/metabolismo , Proteínas/metabolismo , Proteínas Represoras , Animales , Apoptosis/fisiología , Diferenciación Celular , División Celular , Línea Celular , Femenino , Antagonistas de Receptores de GABA-A , Células de la Granulosa/citología , Células de la Granulosa/fisiología , Inhibinas/antagonistas & inhibidores , Mitocondrias/metabolismo , Mitocondrias/fisiología , Mitocondrias/ultraestructura , Fosfoproteínas/antagonistas & inhibidores , Prohibitinas , Ratas , Fracciones Subcelulares/metabolismo , Distribución TisularRESUMEN
Many viruses have overlapping genes and/or regions in which a nucleic acid signal is embedded in a coding sequence. To search for dual-use regions in the hepatitis C virus (HCV), we developed a facile computer-based sequence analysis method to map dual-use regions in coding sequences. Eight diverse full-length HCV RNA and polyprotein sequences were aligned and analyzed. A cluster of unusually conserved synonymous codons was found in the core-encoding region, indicating a potential overlapping open reading frame (ORF). Four peptides (A1, A2, A3, and A4) representing this alternate reading frame protein (ARFP), two others from the HCV core protein, and one from bovine serum albumin (BSA) were conjugated to BSA and used in western blots to test sera for specific antibodies from 100 chronic HCV patients, 44 healthy controls, and 60 patients with non-HCV liver disease. At a 1:20,000 dilution, specific IgGs to three of the four ARFP peptides were detected in chronic HCV sera. Reactivity to either the A1 or A3 peptides (both ARFP derived) was significantly associated with chronic HCV infection, when compared to non-HCV liver disease serum samples (10/100 versus 1/60; p < 0.025). Antibodies to A4 were not detected in any serum sample. Our western blot assays confirmed the presence of specific antibodies to a new HCV antigen encoded, at least in part, in an alternate reading frame (ARF) overlapping the core-encoding region. Because this novel HCV protein stimulates specific immune responses, it has potential value in diagnostic tests and as a component of vaccines. This protein is predicted to be highly basic and may play a role in HCV replication, pathogenesis, and carcinogenesis.
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Empalme Alternativo , Antígenos Virales/genética , Secuencia Conservada , Genes Sobrepuestos , Hepacivirus/genética , Sistemas de Lectura Abierta , Proteínas del Núcleo Viral/genética , Secuencia de Aminoácidos , Antígenos Virales/inmunología , Unión Competitiva , Western Blotting , Genes Virales , Hepacivirus/inmunología , Anticuerpos contra la Hepatitis C/sangre , Anticuerpos contra la Hepatitis C/inmunología , Hepatitis C Crónica/sangre , Hepatitis C Crónica/inmunología , Hepatitis C Crónica/virología , Humanos , Datos de Secuencia Molecular , Péptidos/genética , Péptidos/inmunología , Sensibilidad y EspecificidadRESUMEN
We have shown that IgA-class antimitochondrial autoantibodies (AMA) can be detected in the bile and saliva of patients with PBC, suggesting that AMA are secreted into the luminal fluid across bile ducts and salivary glands. These data prompted us to determine whether AMA of the IgA isotype may be transported across other epithelial mucosa. Therefore, we tested for the presence of AMA in the urine specimens of 83 patients with PBC and 58 non-PBC controls including healthy individuals and patients with other liver diseases. Patients enrolled in this study had no history of renal disease, and we confirmed there was less than 50 microgram/mL of protein in each of the urine specimens. Interestingly, we found that AMA were present in the urine of 71/83 (86%) of all patients with PBC and in 71/78 (91%) of patients with PBC that were serum AMA positive. In contrast, AMA were not detected in any of the 58 control urine specimens. Of particular interest, AMA of the IgA isotype was present in 57/83 (69%) of patients with PBC, and in 52 of these 57, we found secretory-type IgA. In a nested random subgroup of urine samples, the prevalence of the IgA2 AMA was 6/18 (33%), significantly lower than in matched serum samples, 13/16 (81%, P =.007). These data show that AMA of the IgA isotype is secreted into urine from the uroepithelium of patients with PBC, and support the thesis that PBC originated from either a mucosal challenge or a loss of mucosal tolerance.
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Autoanticuerpos/orina , Inmunidad , Cirrosis Hepática Biliar/inmunología , Cirrosis Hepática Biliar/orina , Mitocondrias/inmunología , Urotelio/inmunología , Autoanticuerpos/sangre , Autoanticuerpos/química , Autoanticuerpos/clasificación , Autoantígenos/orina , Mapeo Epitopo , Femenino , Humanos , Inmunoglobulina A/inmunología , Inmunoglobulina A/orina , Inmunoglobulina G/orina , Cirrosis Hepática Biliar/sangre , Isoformas de Proteínas/orina , Proteinuria/orinaRESUMEN
Hepatitis C virus (HCV) is a positive sense virus with a genomic RNA molecule roughly 9,600 nucleotides in length. The single-stranded genomic RNA has a nontranslated region (NTR) at each end and a long open reading frame (coding region) in between. The 5'NTR and portions of the 3'NTR are the most conserved parts of HCV RNA. These conserved regions contain signals for replication and translation. Much of the 5'NTR is folded into a structure that binds ribosomes. This structure, an internal ribosome entry site, promotes the initiation of protein synthesis and is critical for HCV gene expression. The ribosome binding site may extend into the coding region; its exact boundaries are not known. The open reading frame encodes the HCV polyprotein, which is slightly more than 3,000 amino acids in length. The 3'NTR plays a key role in HCV replication and may also influence the rate of HCV protein synthesis. During replication, the genomic RNA is copied by virally encoded enzymes into a complementary antigenomic RNA, which itself is a template for the synthesis of progeny RNAs. At steady state, genomic strands outnumber antigenomic strands about 10 to 1. HCV RNA replication is thought to take place in the cytoplasm and is an error-prone process. It generates a mixed population of RNA sequences (quasispecies), including mutants that may be more fit than the parental type, less fit, or equally fit (but distinct). Natural selection acts upon the progeny RNAs, causing the population to change and drift. Over time, mutation, selection, and population bottlenecks led to the evolution of varied genotypes. The HCV replication complex is a potential source of double-stranded RNA, a powerful inducer of interferon. Thus, HCV-specific double-stranded RNA may trigger the first steps of innate immunity; however, for unknown reasons, the immune system often fails to clear the infection. The plasticity of the HCV genome and the low level of HCV gene expression may counterbalance any immunostimulatory effects of HCV RNA and allow the virus to escape specific immune responses. Antisense drugs and ribozymes directed against HCV RNA are under investigation. Future interventions may include nucleic acid drugs (antisense and ribozymes) and smaller pharmaceuticals that bind to intricate structures in HCV RNA and HCV-specific double-stranded RNA. Infectious clones of HCV RNA are available. These clones and other systems for expressing HCV proteins pave the way for vaccine development.
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Hepacivirus/genética , Interferones/metabolismo , ARN Viral/metabolismo , Proteínas Virales/genética , Genes Virales , Genoma Viral , Hepacivirus/efectos de los fármacos , Humanos , Interferones/administración & dosificación , ARN Viral/efectos de los fármacos , Sensibilidad y Especificidad , Proteínas Virales/efectos de los fármacos , Proteínas Estructurales Virales/genética , Replicación Viral/fisiologíaRESUMEN
Many conditions must be satisfied for an antisense drug to function. It must colocalize with its target RNA at a sufficient concentration for a bimolecular reaction to occur, and it must have a structure that favors association with its target. In addition, if the antisense compound is to form Watson-Crick bonds with the target RNA, it must be complementary to sites that are amenable to binding. Unfortunately, the peculiarities that cause certain sites to be especially vulnerable to antisense compounds are undefined, as discussed previously (Branch, 1998). Because vulnerable target sites have no common properties allowing them to be identified by sequence analysis, most target sites and their antisense counterparts are found through a trial and error process in which oligomers--each complementary to a different site in the target RNA--are tested individually to find the one with the greatest specificity and lowest inhibitory concentration (IC50). However, testing antisense molecules one at a time can be a taxing process, and there is great interest in developing cell-free screening methods that can reduce the number of compounds that must be tested in cells and in whole animals. These cell-free screens are designed to generate short lists of target sites that include the ideal site--the site most vulnerable to antisense ablation in vivo. They are based on the unproven assumption that ideal sites have distinctive properties, such as susceptibility to RNase H-mediated cleavage, that allow them to be detected in cell-free assays. This is a review of data emerging from studies using RNase H-based screens and a summary of the challenges confronting these and any similar methods that use naked RNAs as surrogates for intracellular RNAs. It is not yet clear if cell-free screening methods will be effective.
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Evaluación Preclínica de Medicamentos/métodos , Oligonucleótidos Antisentido/farmacología , Humanos , Conformación de Ácido Nucleico , ARN/química , Ribonucleasa H/metabolismoRESUMEN
Antisense molecules and ribozymes capture the imagination with their promise of rational drug design and exquisite specificity. However, they are far more difficult to produce than was originally anticipated, and their ability to eliminate the function of a single gene has never been proven. Furthermore, a wide variety of unexpected non-antisense effects have come to light. Although some of these side effects will almost certainly have clinical value, they make it hard to produce drugs that act primarily through true antisense mechanisms and complicate the use of antisense compounds as research reagents. To minimize unwanted non-antisense effects, investigators are searching for antisense compounds and ribozymes whose target sites are particularly vulnerable to attack. This is a challenging quest.
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Oligonucleótidos Antisentido , Animales , Secuencia de Bases , Diseño de Fármacos , Marcación de Gen , Humanos , Oligonucleótidos Antisentido/genética , Oligonucleótidos Antisentido/farmacología , ARN Catalítico/farmacologíaRESUMEN
Therapeutic ribozymes are created through a multistep process that requires trial and error. There are few established rules governing ribozyme design, but guidelines are emerging. It is not yet known whether hammerheads and hairpins, the two ribozymes most widely studied as potential gene therapy agents, have the inherent capability to ablate single genes. Their capacity for specificity and selectivity remains to be explored through rigorous experimentation. These experiments require a battery of control molecules, the characteristics of which are outlined here. Methods for completing the steps in the ribozyme development process, from the selection of a target gene to the quantitation of RNA levels, are also presented and discussed.
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Terapia Genética , ARN Catalítico , Animales , Secuencia de Bases , Ingeniería Genética , Humanos , Conformación de Ácido Nucleico , ARN/químicaRESUMEN
Antisense pharmaceutical research has sought to provide drugs that would yield effective therapies for diseases resulting from the production of deleterious proteins. The original concept was straightforward: eliminate production of unwanted proteins, such as oncogenic proteins, by blocking the function of their mRNAs; and block their mRNAs by adding "antisense" nucleic acids that bind them through complementary base pairing. However, it has proven difficult to develop clinically useful antisense strategies. Conventional antisense nucleic acids are large, highly charged, complex molecules that interact with a wide variety of unintended cellular and microbial components, often causing "nonantisense effects." It is now clear that a broad knowledge of nucleic acid biochemistry will be needed to optimize antisense molecules for use in patients. The efficacy of naturally occurring antisense molecules and the success of antisense agricultural strategies prove that antisense approaches can be powerful and specific. Pharmaceutical antisense research can be expected to yield many valuable products once sufficient information about antisense mechanisms has been gathered and applied. This article explains the biochemical events that give rise to both antisense and nonantisense effects and provides guidelines for designing and evaluating antisense experiments.
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Oligonucleótidos Antisentido/química , Oligonucleótidos Antisentido/uso terapéutico , Oligonucleótidos/química , Animales , Secuencia de Bases , ADN sin Sentido , Diseño de Fármacos , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Modelos Biológicos , Datos de Secuencia Molecular , Conformación de Ácido Nucleico , Oligonucleótidos Antisentido/farmacología , ARN Mensajero/antagonistas & inhibidores , Ribonucleasa H/metabolismoRESUMEN
Viroids and other circular subviral RNA pathogens, such as the hepatitis delta agent, use a rolling circle replication cycle requiring an intact circular RNA. However, many infectious RNAs have the potential to form self-cleavage structures, whose formation must be controlled in order to preserve the circular replication template. The native structure of delta RNA contains a highly conserved element of local tertiary structure which is composed of sequences partially overlapping those needed to form the self-cleavage motif. A bimolecular complex containing the tertiary structure can be made. We show that when it is part of this bimolecular complex the potential cleavage site is protected and is not cleaved by the delta ribozyme, demonstrating that the element of local tertiary structure can function as a ribozyme control element in vitro. Physical studies of the complex containing this element were carried out. The complex binds magnesium ions and is not readily dissociated by EDTA under the conditions tested; > 50% of the complexes remain following incubation in 1 mM EDTA at 60 degrees C for 81 min. The thermal stability of the complex is reduced in the presence of sodium ions. A DNA complex and a perfect RNA duplex studied in parallel showed a similar effect, but of lesser magnitude. The RNA complex melts at temperatures approximately 10 degrees C lower in buffers containing 0.5 mM MgCl2 and 100 mM NaCl than in buffers containing 0.5 mM MgCl2 with no NaCl (78.1 compared with 87.7 degrees C). The element of local tertiary structure in delta genomic RNA appears to be a molecular clamp whose stability is highly sensitive to ion concentration in the physiological range.