Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 15 de 15
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Artigo em Inglês | MEDLINE | ID: mdl-38762387

RESUMO

BACKGROUND: Quality improvement (QI) programs require significant financial investment. The authors evaluated the cost-effectiveness of a physician-led, performance-incentivized, QI intervention that increased appropriate peripherally inserted central catheter (PICC) use. METHODS: The authors used an economic evaluation from a health care sector perspective. Implementation costs included incentive payments to hospitals and costs for data abstractors and the coordinating center. Effectiveness was calculated from propensity score-matched observations across two time periods for complications (venous thromboembolism [VTE], central line-associated bloodstream infection [CLABSI], and catheter occlusion): preintervention period (January 2015 through December 2016) and intervention period (January 2017 through December 2021). Cost-effectiveness was presented as the cost-offset per averted complication, reflecting the health care costs avoided due to having lower complication rates. RESULTS: Across 35 hospitals, this study sampled 17,418 PICCs placed preintervention and 26,004 placed during the intervention period. PICC complications decreased significantly following the intervention. CLABSIs decreased from 2.1% to 1.5%, VTEs from 3.2% to 2.3%, and catheter occlusions from 10.8% to 7.0% (all p < 0.01). Estimated number of complications prevented included 871 CLABSIs, 2,535 VTEs, and 8,743 catheter occlusions. Project implementation costs were $31.8 million, and the cost-offset related to avoided complications was $64.4 million. Each participating hospital averaged $932,073 in cost-offset over seven years, and the average cost-offset per complication averted was $2,614 (95% CI [confidence interval] $2,314-$3,003). CONCLUSION: A large-scale, multihospital QI initiative to improve appropriate PICC use yielded substantial return on investment from cost-offset of prevented complications.

2.
PLoS One ; 19(3): e0285912, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38527020

RESUMO

Remote sensing of spectral reflectance is a crucial parameter in precision agriculture. In particular, the visual color produced from reflected light can be used to determine plant health (VIS-IR) or attract pollinators (Near-UV). However, the UV spectral reflectance studies largely focus on non-crop plants, even though they provide essential information for plant-pollinator interactions. This literature review presents an overview of UV-reflectance in crops, identifies gaps in the literature, and contributes new data based on strawberry cultivars. The study found that most crop spectral reflectance studies relied on lab-based methodologies and examined a wide spectral range (Near UV to IR). Moreover, the plant family distribution largely mirrored global food market trends. Through a spectral comparison of white flowering strawberry cultivars, this study discovered visual differences for pollinators in the Near UV and Blue ranges. The variation in pollinator visibility within strawberry cultivars underscores the importance of considering UV spectral reflectance when developing new crop breeding lines and managing pollinator preferences in agricultural fields.


Assuntos
Fragaria , Tecnologia de Sensoriamento Remoto , Melhoramento Vegetal , Produtos Agrícolas
3.
Chest ; 165(4): 847-857, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-37898185

RESUMO

BACKGROUND: Vasopressors traditionally are administered via central access, but newer data suggest that peripheral administration may be safe and may avoid delays and complications associated with central line placement. RESEARCH QUESTION: How commonly are vasopressors initiated through peripheral IV lines in routine practice? Is vasopressor initiation route associated with in-hospital mortality? STUDY DESIGN AND METHODS: This retrospective cohort study included adults hospitalized with sepsis (November 2020-September 2022) at 29 hospitals in the Michigan Hospital Medicine Safety Consortium, a Collaborative Quality Initiative sponsored by Blue Cross Blue Shield of Michigan. We assessed route of early vasopressor initiation, factors and outcomes associated with peripheral initiation, and timing of central line placement. RESULTS: Five hundred ninety-four patients received vasopressors within 6 h of hospital arrival and were included in this study. Peripheral vasopressor initiation was common (400/594 [67.3%]). Patients with peripheral vs central initiation were similar; BMI was the only patient factor associated independently with initiation route (adjusted OR [aOR] of peripheral initiation [per 1-kg/m2 increase], 0.98; 95% CI, 0.97-1.00; P = .015). The specific hospital showed a large impact on initiation route (median OR, 2.19; 95% CI, 1.31-3.07). Compared with central initiation, peripheral initiation was faster (median, 2.5 h vs 2.7 h from hospital arrival; P = .002), but was associated with less initial norepinephrine use (84.3% vs 96.8%; P = .001). We found no independent association between initiation route and in-hospital mortality (32.3% vs 42.2%; aOR, 0.66; 95% CI, 0.39-1.12). No tissue injury from peripheral vasopressors was documented. Of patients with peripheral initiation, 135 of 400 patients (33.8%) never received a central line. INTERPRETATION: Peripheral vasopressor initiation was common across Michigan hospitals and had practical benefits, including expedited vasopressor administration and avoidance of central line placement in one-third of patients. However, the findings of wide practice variation that was not explained by patient case mix and lower use of first-line norepinephrine with peripheral administration suggest that additional standardization may be needed.


Assuntos
Hipotensão Controlada , Hipotensão , Sepse , Choque Séptico , Humanos , Estudos Retrospectivos , Michigan/epidemiologia , Hipotensão Controlada/efeitos adversos , Vasoconstritores/uso terapêutico , Norepinefrina , Choque Séptico/complicações , Sepse/tratamento farmacológico , Sepse/complicações , Hipotensão/tratamento farmacológico , Hipotensão/etiologia
4.
Crit Care Explor ; 5(11): e1004, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37954901

RESUMO

OBJECTIVES: To identify opportunities for improving hospital-based sepsis care and to inform an ongoing statewide quality improvement initiative in Michigan. DESIGN: Surveys on hospital sepsis processes, including a self-assessment of practices using a 3-point Likert scale, were administered to 51 hospitals participating in the Michigan Hospital Medicine Safety Consortium, a Collaborative Quality Initiative sponsored by Blue Cross Blue Shield of Michigan, at two time points (2020, 2022). Forty-eight hospitals also submitted sepsis protocols for structured review. SETTING: Multicenter quality improvement consortium. SUBJECTS: Fifty-one hospitals in Michigan. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of the included hospitals, 92.2% (n = 47/51) were nonprofit, 88.2% (n = 45/51) urban, 11.8% (n = 6/51) rural, and 80.4% (n = 41/51) teaching hospitals. One hundred percent (n = 51/51) responded to the survey, and 94.1% (n = 48/51) provided a sepsis policy/protocol. All surveyed hospitals used at least one quality improvement approach, including audit/feedback (98.0%, n = 50/51) and/or clinician education (68.6%, n = 35/51). Protocols included the Sepsis-1 (18.8%, n = 9/48) or Sepsis-2 (31.3%, n = 15/48) definitions; none (n = 0/48) used Sepsis-3. All hospitals (n = 51/51) used at least one process to facilitate rapid sepsis treatment, including order sets (96.1%, n = 49/51) and/or stocking of commonly used antibiotics in at least one clinical setting (92.2%, n = 47/51). Treatment protocols included guidance on antimicrobial therapy (68.8%, n = 33/48), fluid resuscitation (70.8%, n = 34/48), and vasopressor administration (62.5%, n = 30/48). On self-assessment, hospitals reported the lowest scores for peridischarge practices, including screening for cognitive impairment (2.0%, n = 1/51 responded "we are good at this") and providing anticipatory guidance (3.9%, n = 2/51). There were no meaningful associations of the Centers for Medicare and Medicaid Services' Severe Sepsis and Septic Shock: Management Bundle performance with differences in hospital characteristics or sepsis policy document characteristics. CONCLUSIONS: Most hospitals used audit/feedback, order sets, and clinician education to facilitate sepsis care. Hospitals did not consistently incorporate organ dysfunction criteria into sepsis definitions. Existing processes focused on early recognition and treatment rather than recovery-based practices.

5.
J Hosp Med ; 18(11): 969-977, 2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-37771294

RESUMO

BACKGROUND: Midline catheters (midlines) are increasingly used in patients with advanced chronic kidney disease (CKD). OBJECTIVE: This study describes current practice and acute complications associated with midlines in CKD patients. DESIGNS, SETTING, AND PARTICIPANTS: Trained abstractors at 66 hospitals from the Michigan Hospital Medicine Safety (HMS) Consortium collected data on a sample of patients who received a midline during hospitalization. Patients were classified as having advanced CKD if their estimated glomerular filtration rate was <45 mL/min/1.73 m2 . MAIN OUTCOME AND MEASURES: Midline recipients with advanced CKD were compared to those without advanced CKD by patient, provider, and device characteristics, and by the occurrence of acute complications including major (e.g., upper extremity deep vein thrombosis [UE-DVT] and catheter-related bloodstream infection [CRBSI]) or minor (e.g., catheter occlusion, catheter dislodgement, infiltration, superficial thrombophlebitis, and leaking at insertion site) events. Multivariable mixed effects logistic regression was used to evaluate the association between catheter-related complications and stage of CKD. RESULTS: Of 21,415 midline recipients, 5272 (24.6%) had advanced CKD, while 16,143 (75.4%) did not. Most midlines were single lumen (90.5%) and remained in place for a median of 6 days. A major or minor midline complication occurred in 804 (15.3%) patients with and 2239 (14.4%) patients without advanced CKD (adjusted odds ratios = 1.04; 95% confidence interval: 0.94-1.14). Among patients with advanced CKD, CRBSI occurred in 13 patients (0.2%) and UE-DVT occurred in 65 patients (1.2%). The proportion of advanced CKD among midline recipients and the frequency of midline-related complications varied across hospitals (interquartile range [IQR] = 19.2% to 29.8% [median = 25.0%] and IQR = 11.0%-18.9% [median = 15.4%], respectively).


Assuntos
Cateterismo Venoso Central , Insuficiência Renal Crônica , Tromboflebite , Humanos , Cateterismo Venoso Central/efeitos adversos , Catéteres , Pacientes , Complicações Pós-Operatórias/etiologia
6.
Drug Discov Today ; 28(4): 103520, 2023 04.
Artigo em Inglês | MEDLINE | ID: mdl-36754144

RESUMO

There is increasing interest in clinical trials that use technologies and other innovative operational approaches to organise trial activities around trial participants instead of investigator sites. A range of terms has been introduced to refer to this operational clinical trial model, including virtual, digital, remote, and decentralised clinical trials (DCTs). However, this lack of standardised terminology can cause confusion over what a particular trial model entails and for what purposes it can be used, hampering discussions by stakeholders on its acceptability and suitability. Here, we review the different terms described in the scientific literature, advocate the consistent use of a unified term, 'decentralised clinical trial,' and provide a detailed definition of this term.


Assuntos
Assistência Centrada no Paciente , Humanos , Consenso
7.
Trials ; 23(1): 856, 2022 Oct 06.
Artigo em Inglês | MEDLINE | ID: mdl-36203202

RESUMO

BACKGROUND: The COVID-19 pandemic significantly impacted the conduct of clinical trials through delay, interruption or cancellation. Decentralised methods in clinical trials could help to continue trials during a pandemic. This paper presents the results of an exploratory study conducted early in the pandemic to gain insight into and describe the experiences of organisations involved in clinical trials, with regard to the impact of COVID-19 on the conduct of trials, and the adoption of decentralised methods prior to, and as mitigation for the impact, of COVID-19. METHODS: A survey with 11 open-ended and four multiple choice questions was conducted in June 2020 among member organisations of the public-private "Trials@Home" consortium. The survey investigated (1) the impact and challenges of COVID-19 on the continuation of ongoing clinical trials, (2) the adoption of decentralised methods in clinical trials prior to and as a mitigation strategy for COVID-19, (3) the challenges of conducting clinical trials during COVID-19, (4) the expected permanency of COVID-19-driven changes to the adoption of decentralised methods in clinical trials, and (5) lessons learned from conducting clinical trials during the COVID-19 pandemic. A thematic, inductive analysis of open survey questions was performed, complemented with descriptive statistics (frequencies and distributions). RESULTS: The survey had a response rate of 81%. All organisations included in the analysis (n = 18) implemented (some) decentralised methods in their clinical trials prior to COVID-19, and 15 (83%) implemented decentralised methods as mitigation for COVID-19. Decentralised methods for IMP supply, patient-health care provider interaction and communication, clinic visits and source document verification were used more often as mitigation strategies than they were used prior to COVID-19. Many respondents expect to maintain those decentralised methods they implemented during COVID-19 in ongoing trials, as well as implement them in future trials. CONCLUSIONS: Decentralised methods are a widely implemented mitigation strategy for trial conduct in the face of the COVID-19 pandemic. The results of this survey show that there is an interest to continue the use of decentralised methods in future trials, but important points of attention have been identified that need solutions to help guide the transition from the traditional trial model to a more decentralised trial model.


Assuntos
COVID-19 , Humanos , Estudos Transversais , Pandemias , SARS-CoV-2
8.
Am J Emerg Med ; 59: 217.e5-217.e7, 2022 09.
Artigo em Inglês | MEDLINE | ID: mdl-35811188

RESUMO

Lithium is considered a mood stabilizer for bipolar affective disorders, but it has a narrow therapeutic index of 0.6-1.2 mEq/L. This can easily result in toxic levels after minimal changes in renal function or individual patient's pharmacokinetics. Lithium toxicity can arise with levels as low as 1.5 mEq, and there are limited therapeutic options to treat these patients presenting to the emergency department (ED). At therapeutic levels 95% of lithium is eliminated unchanged by the kidneys. However, previous literature has examined sodium polystyrene sulfonate (SPS) as an option to reduce lithium levels by binding the lithium cation and enhancing its excretion via the gastrointestinal tract. This suggests there may be an increased degree of non-renal clearance and altered toxicokinetics at supratherapeutic levels. However, SPS has been associated with intestinal necrosis and may cause treatment limiting hypokalemia, and is therefore not commonly recommended in treatment algorithms for lithium toxicity. A newer cation exchange resin, sodium zirconium cyclosilicate (SZC), may provide a safer alternative to SPS while also aiding in the clearance of lithium. We present a patient case where a patient with symptomatic acute-on-chronic lithium toxicity had increased clearance of lithium after a dose of SZC.


Assuntos
Hiperpotassemia , Hipopotassemia , Resinas de Troca de Cátion/uso terapêutico , Humanos , Hiperpotassemia/tratamento farmacológico , Hipopotassemia/complicações , Lítio/toxicidade , Potássio/uso terapêutico , Silicatos/uso terapêutico
9.
Am J Emerg Med ; 57: 149-152, 2022 07.
Artigo em Inglês | MEDLINE | ID: mdl-35580546

RESUMO

OBJECTIVE: Patients experiencing an intracranial hemorrhage (ICH) on oral anticoagulants often require rapid reversal. This study evaluated patients taking factor Xa inhibitors or warfarin that received reversal with 4-factor prothrombin complex concentrate (4F-PCC) for an ICH. The objective of the study was to determine if the efficacy of 4F-PCC for the reversal of factor Xa inhibitors is noninferior to its use in warfarin reversal in patients with ICH. METHODS: This was a retrospective, single center, noninferiority trial. Patients presenting to the emergency department with ICH were divided into two cohorts: those taking factor Xa inhibitors versus those taking warfarin. In each cohort, patients received anticoagulation reversal with weight-based 4F-PCC. The primary endpoint was hemostatic efficacy defined as ≤20% expansion in hematoma volume on repeat computed tomography imaging. A pre-specified noninferiority margin of -10% was selected to evaluate the difference between groups for the primary endpoint. RESULTS: A total of 221 patients were included in the study (factor Xa inhibitors, n = 87; warfarin, n = 134). Effective hemostasis was achieved in 70 patients (81%) on factor Xa inhibitors compared to 111 patients (83%) on warfarin, (-2.4% difference, [95% confidence interval, -12.87 to 8.12]; p = 0.654). There was no statistically significant difference between groups with regards to the primary outcome; however, the use of 4F-PCC in factor Xa inhibitor reversal was not noninferior when compared to 4F-PCC use for warfarin reversal. Hospital length of stay and discharge disposition were similar between cohorts. CONCLUSIONS: The efficacy of 4F-PCC in reversing factor Xa inhibitor-related ICH compared to warfarin-related ICH was not significantly different between groups; however, these results did not prove noninferiority. Further study is warranted to delineate 4F-PCC's role in reversing factor Xa inhibitors in patients with ICH.


Assuntos
Inibidores do Fator Xa , Hemostáticos , Anticoagulantes/uso terapêutico , Fatores de Coagulação Sanguínea/farmacologia , Fatores de Coagulação Sanguínea/uso terapêutico , Fator Xa/farmacologia , Fator Xa/uso terapêutico , Inibidores do Fator Xa/uso terapêutico , Fibrinolíticos , Hemostasia , Hemostáticos/uso terapêutico , Humanos , Hemorragias Intracranianas/diagnóstico por imagem , Hemorragias Intracranianas/tratamento farmacológico , Estudos Retrospectivos , Varfarina/uso terapêutico
10.
Neuropharmacology ; 133: 276-288, 2018 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-29378214

RESUMO

Neural stem cell-driven adult neurogenesis contributes to the integrity of the hippocampus. Excessive alcohol consumption in alcoholism results in hippocampal degeneration that may recover with abstinence. Reactive, increased adult neurogenesis during abstinence following alcohol dependence may contribute to recovery, but the mechanism driving reactive neurogenesis is not known. Therefore, adult, male rats were exposed to alcohol for four days and various markers were used to examine cell cycle dynamics, the percentage and number of neural progenitor cell subtypes, and the percentage of quiescent versus activated progenitors. Using a screen for cell cycle perturbation, we showed that the cell cycle is not likely altered at 7 days in abstinence. As the vast majority of Bromodeoxyuridine-positive (+) cells were co-labeled with progenitor cell marker, Sox2, we then developed a quadruple fluorescent labeling scheme to examine Type-1, -2a, -2b and -3 progenitor cells simultaneously. Prior alcohol dependence indiscriminately increased all subtypes at 7 days, the peak of the reactive proliferation. An evaluation of the time course of reactive cell proliferation revealed that cells begin proliferating at 5 days post alcohol, where only actively dividing Type 2 progenitors were increased by alcohol. Furthermore, prior alcohol increased the percentage of actively dividing Sox2+ progenitors, which supported that reactive neurogenesis is likely due to the activation of progenitors out of quiescence. These observations were associated with granule cell number returning to normal at 28 days. Therefore, activating stem and progenitor cells out of quiescence may be the mechanism underlying hippocampal recovery in abstinence following alcohol dependence.


Assuntos
Alcoolismo/fisiopatologia , Hipocampo/fisiopatologia , Células-Tronco Neurais/fisiologia , Neurogênese/fisiologia , Alcoolismo/patologia , Análise de Variância , Animais , Bromodesoxiuridina/metabolismo , Ciclo Celular/efeitos dos fármacos , Ciclo Celular/fisiologia , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/fisiologia , Depressores do Sistema Nervoso Central/administração & dosagem , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Etanol/administração & dosagem , Hipocampo/efeitos dos fármacos , Antígeno Ki-67/metabolismo , Masculino , Proteínas do Tecido Nervoso/metabolismo , Células-Tronco Neurais/efeitos dos fármacos , Neurogênese/efeitos dos fármacos , Ratos , Ratos Sprague-Dawley , Fatores de Transcrição SOXB1/metabolismo , Fatores de Tempo
11.
Vaccine ; 26(26): 3312-21, 2008 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-18486283

RESUMO

Protection afforded by HIV Tat-based vaccines has differed in Indian rhesus and Mauritian cynomolgus macaques. We evaluated native Tat and Ad-HIVtat priming/Tat-boosting regimens in both species. Both vaccines were immunogenic. Only the Ad-tat regimen modestly reduced acute viremia in rhesus macaques after SHIV(89.6P) challenge. Confounding variables uncovered in Mauritian macaques included significant associations of susceptibility to infection with MHC class IB and class II H2 and H5 haplotypes, and resistance to infection with class IB haplotypes H3 and H6. Although protection here was limited, Tat-based vaccines incorporating other HIV components have shown greater efficacy. Combination strategies should be further explored.


Assuntos
Vacinas contra a AIDS/imunologia , Suscetibilidade a Doenças , Haplótipos , Antígenos de Histocompatibilidade Classe II/genética , Antígenos de Histocompatibilidade Classe I/genética , Síndrome de Imunodeficiência Adquirida dos Símios/prevenção & controle , Produtos do Gene tat do Vírus da Imunodeficiência Humana/imunologia , Animais , Macaca fascicularis , Macaca mulatta , Carga Viral , Viremia
12.
J Virol ; 81(7): 3414-27, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17229693

RESUMO

We previously demonstrated that replication-competent adenovirus (Ad)-simian immunodeficiency virus (SIV) recombinant prime/protein boost regimens elicit potent immunogenicity and strong, durable protection of rhesus macaques against SIV(mac251). Additionally, native Tat vaccines have conferred strong protection against simian/human immunodeficiency virus SHIV(89.6P) challenge of cynomolgus monkeys, while native, inactivated, or vectored Tat vaccines have failed to elicit similar protective efficacy in rhesus macaques. Here we asked if priming rhesus macaques with replicating Ad-human immunodeficiency virus (HIV) tat and boosting with the Tat protein would elicit protection against SHIV(89.6P). We also evaluated a Tat/Env regimen, adding an Ad-HIV env recombinant and envelope protein boost to test whether envelope antibodies would augment acute-phase protection. Further, expecting cellular immunity to enhance chronic viremia control, we tested a multigenic group: Ad-HIV tat, -HIV env, -SIV gag, and -SIV nef recombinants and Tat, Env, and Nef proteins. All regimens were immunogenic. A hierarchy was observed in enzyme-linked immunospot responses (with the strongest response for Env, followed by Gag, followed by Nef, followed by Tat) and antibody titers (with the highest titer for Env, followed by Tat, followed by Nef, followed by Gag). Following intravenous SHIV(89.6P) challenge, all macaques became infected. Compared to controls, no protection was seen in the Tat-only group, confirming previous reports for rhesus macaques. However, the multigenic group blunted acute viremia by approximately 1 log (P = 0.017), and both the multigenic and Tat/Env groups reduced chronic viremia by 3 and 4 logs, respectively, compared to controls (multigenic, P = 0.0003; Tat/Env, P < 0.0001). The strikingly greater reduction in the Tat/Env group than in the multigenic group (P = 0.014) was correlated with Tat and Env binding antibodies. Since prechallenge anti-Env antibodies lacked SHIV(89.6P)-neutralizing activity, other functional anti-Env and anti-Tat activities are under investigation, as is a possible synergy between the Tat and Env immunogens.


Assuntos
Adenoviridae/genética , Produtos do Gene env/metabolismo , Produtos do Gene tat/metabolismo , HIV/imunologia , HIV/metabolismo , Vírus da Imunodeficiência Símia/fisiologia , Replicação Viral , Animais , Anticorpos Antivirais/imunologia , Anticorpos Antivirais/farmacologia , Produtos do Gene env/genética , Produtos do Gene env/imunologia , Produtos do Gene tat/genética , Produtos do Gene tat/imunologia , HIV/genética , Memória Imunológica/imunologia , Linfócitos/efeitos dos fármacos , Linfócitos/imunologia , Macaca mulatta , Produtos do Gene tat do Vírus da Imunodeficiência Humana
13.
Biochemistry ; 44(10): 3915-25, 2005 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-15751967

RESUMO

Enhancement of strand exchange by nucleocapsid protein (NC) is proposed to occur during retroviral recombination. The mechanism was examined using an RNA (donor)-DNA hybrid that mimicked a retrovirus replication intermediate. This consisted of a 25 base pair hybrid region flanked on each side by single-stranded RNA or DNA. A second set of acceptor RNAs that could bind to the 25-base hybrid region and to various lengths of additional bases on the DNA was used to displace the donor by hybridizing with the DNA. Displacement required a complementary single-stranded DNA region outside the donor-DNA 25-nucleotide hybrid region. NC enhanced displacement slightly when the acceptor could bind 10 nucleotides and significantly when binding 22 or more nucleotides in the single-stranded region. Two mutated acceptors that bound over 47 total nucleotides on the DNA (22 in the single-stranded region plus 25 in the hybrid region) were constructed. One had three mismatches in the hybrid region; the other, three in the single-stranded region and one in the hybrid region. Each acceptor bound the DNA with approximately equal thermodynamic stability, yet NC stimulated exchange with the former and actually inhibited with the latter. This emphasized the importance of the single-stranded region in NC stimulation. The results support a mechanism where NC enhances the docking of the acceptor to the single-stranded region and then the acceptor "zippers" through the hybrid and displaces the donor. Results with the mutated acceptors indicate that NC may actually inhibit strand exchange between genomes in nonhomologous regions.


Assuntos
DNA de Cadeia Simples/química , DNA Viral/química , HIV-1/genética , Proteínas do Nucleocapsídeo/genética , RNA Viral/química , Recombinação Genética , Pareamento de Bases/genética , DNA Complementar/química , DNA Complementar/genética , DNA de Cadeia Simples/genética , DNA de Cadeia Simples/metabolismo , DNA Viral/genética , DNA Viral/metabolismo , HIV-1/química , Modelos Químicos , Hibridização de Ácido Nucleico , Proteínas do Nucleocapsídeo/química , Proteínas do Nucleocapsídeo/metabolismo , Mutação Puntual , RNA Viral/genética , RNA Viral/metabolismo , Termodinâmica
14.
J Biol Chem ; 278(33): 30755-63, 2003 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-12783894

RESUMO

The replication process of human immunodeficiency virus requires a number of nucleic acid annealing steps facilitated by the hybridization and helix-destabilizing activities of human immunodeficiency virus nucleocapsid (NC) protein. NC contains two CCHC zinc finger motifs numbered 1 and 2 from the N terminus. The amino acids surrounding the CCHC residues differ between the two zinc fingers. Assays were preformed to investigate the activities of the fingers by determining the effect of mutant and wild-type proteins on annealing of 42-nucleotide RNA and DNA complements. The mutants 1.1 NC and 2.2 NC had duplications of the N- and C-terminal zinc fingers in positions 1 and 2. The mutant 2.1 NC had the native zinc fingers with their positions switched. Annealing assays were completed with unstructured and highly structured oligonucleotide complements. 2.2 NC had a near wild-type level of annealing of unstructured nucleic acids, whereas it was completely unable to stimulate annealing of highly structured nucleic acids. In contrast, 1.1 NC was able to stimulate annealing of both unstructured and structured substrates, but to a lesser degree than the wild-type protein. Results suggest that finger 1 has a greater role in unfolding of strong secondary structures, whereas finger 2 serves an accessory role that leads to a further increase in the rate of annealing.


Assuntos
HIV-1/genética , Proteínas do Nucleocapsídeo/genética , Oligonucleotídeos/química , Dedos de Zinco/genética , DNA Complementar/química , DNA Complementar/genética , Transferência Ressonante de Energia de Fluorescência , HIV-1/crescimento & desenvolvimento , Mutação , Conformação de Ácido Nucleico , Proteínas do Nucleocapsídeo/química , Oligonucleotídeos/genética , Estrutura Terciária de Proteína , RNA/química , RNA/genética
15.
J Biol Chem ; 278(18): 15702-12, 2003 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-12595541

RESUMO

An in vitro strand transfer assay that mimicked recombinational events occurring during reverse transcription in HIV-1 was used to assess the role of nucleocapsid protein (NC) in strand transfer. Strand transfer in highly structured nucleic acid species from the U3 3' long terminal repeats, gag-pol frameshift region, and Rev response element were strongly enhanced by NC. In contrast, weakly structured templates from the env and pol-vif regions transferred well without NC and showed lower enhancement. The lack of strong polymerase pause sites in the latter regions demonstrated that non-pause driven mechanisms could also promote transfer. Assays conducted using NC zinc finger mutants supported a differential role for the two fingers in strand transfer with finger 1 (N-terminal) being more important on highly structured RNAs. Overall this report suggests a role for structural intricacies of RNA templates in determining the extent of influence of NC on recombination and illustrates that strand transfer may occur by several different mechanisms depending on the structural nature of the RNA.


Assuntos
Genoma Viral , HIV/genética , Proteínas do Nucleocapsídeo/fisiologia , RNA Viral/metabolismo , Sequência de Bases , Dados de Sequência Molecular , Proteínas do Nucleocapsídeo/química , RNA Viral/química , Recombinação Genética , Dedos de Zinco
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...