Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 16 de 16
Filtrar
1.
Palliat Med ; 38(1): 121-130, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38032069

RESUMO

BACKGROUND: Although prescribing and deprescribing practices in older people have been the subject of much research generally, there are limited data in older people at the end of life. This highlights the need for research to determine prescribing and deprescribing patterns, as a first step to facilitate guideline development for medicines optimisation in this vulnerable population. AIMS: To examine prescribing and deprescribing patterns in older people at the end of life and to determine the prevalence of potentially inappropriate medication use. DESIGN: A longitudinal, retrospective cohort study where medical records of eligible participants were reviewed, and data extracted. Medication appropriateness was assessed using two sets of consensus-based criteria; the STOPPFrail criteria and criteria developed by Morin et al. SETTING/PARTICIPANTS: Decedents aged 65 years and older admitted continuously for at least 14 days before death to three inpatient hospice units across Northern Ireland, who died between 1st January and 31st December 2018, and who had a known diagnosis, known cause of death and prescription data. Unexpected/sudden deaths were excluded. RESULTS: Polypharmacy was reported to be continued until death in 96.2% of 106 decedents (mean age of 75.6 years). Most patients received at least one potentially inappropriate medication at the end of life according to the STOPPFrail and the criteria developed by Morin et al. (57.5 and 69.8% respectively). Limited prevalence of proactive deprescribing interventions was observed. CONCLUSIONS: In the absence of systematic rationalisation of drug treatments, a substantial proportion of older patients continued to receive potentially inappropriate medication until death.


Assuntos
Desprescrições , Cuidados Paliativos na Terminalidade da Vida , Hospitais para Doentes Terminais , Humanos , Idoso , Prescrição Inadequada/prevenção & controle , Estudos Retrospectivos , Lista de Medicamentos Potencialmente Inapropriados , Morte
2.
Disabil Rehabil ; 44(4): 542-548, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32525405

RESUMO

BACKGROUND: Impaired postural control is a common symptom in people with multiple sclerosis. Multiple sclerosis frequently presents with asymmetric motor involvement. One measurement yet to be evaluated for asymmetry in people with multiple sclerosis is the soleus Hoffmann reflex. PURPOSE: To measure the soleus Hoffmann reflex between limbs and correlate reflex asymmetry with postural control. MATERIAL AND METHODS: 16 participants completed four sessions of Hoffmann reflex testing and one session of balance testing. RESULTS: Multiple sclerosis participants had significantly greater reflex asymmetry (p = 0.01). The multiple sclerosis group had a significantly lower overall sensory organization testing composite score (p < 0.05), indicating sensory interpretation conflict that resulted in greater postural instability. Multiple sclerosis participants produced a significantly shorter endpoint and maximum excursion (p < 0.01) during limits of stability testing. Hoffmann reflex asymmetry was negatively related to forward endpoint excursion (p < 0.05), maximum excursion (p ≤ 0.01). CONCLUSIONS: Multiple sclerosis participants had greater soleus Hoffmann reflex asymmetry, which appears to significantly influence forward postural control.Implications for rehabilitationSoleus Hoffmann reflex asymmetry appears to influence postural stability.The soleus Hoffmann reflex is capable of adapting to different modes of exercise; therefore, to reduce H-reflex asymmetry it is recommended to individualize physical rehabilitative programming.Assessing the soleus Hoffmann reflex in people with multiple sclerosis during health screenings could be of use to clinical and rehabilitative practitioners.


Assuntos
Reflexo H , Esclerose Múltipla , Eletromiografia , Humanos , Músculo Esquelético , Equilíbrio Postural
3.
BMC Med ; 16(1): 174, 2018 10 11.
Artigo em Inglês | MEDLINE | ID: mdl-30305088

RESUMO

BACKGROUND: Ensuring effective identification and management of sepsis is a healthcare priority in many countries. Recommendations for sepsis management in primary care have been produced, but in complex healthcare systems, an in-depth understanding of current system interactions and functioning is often essential before improvement interventions can be successfully designed and implemented. A structured participatory design approach to model a primary care system was employed to hypothesise gaps between work as intended and work delivered to inform improvement and implementation priorities for sepsis management. METHODS: In a Scottish regional health authority, multiple stakeholders were interviewed and the records of patients admitted from primary care to hospital with possible sepsis analysed. This identified the key work functions required to manage these patients successfully, the influence of system conditions (such as resource availability) and the resulting variability of function output. This information was used to model the system using the Functional Resonance Analysis Method (FRAM). The multiple stakeholder interviews also explored perspectives on system improvement needs which were subsequently themed. The FRAM model directed an expert group to reconcile improvement suggestions with current work systems and design an intervention to improve clinical management of sepsis. RESULTS: Fourteen key system functions were identified, and a FRAM model was created. Variability was found in the output of all functions. The overall system purpose and improvement priorities were agreed. Improvement interventions were reconciled with the FRAM model of current work to understand how best to implement change, and a multi-component improvement intervention was designed. CONCLUSIONS: Traditional improvement approaches often focus on individual performance or a specific care process, rather than seeking to understand and improve overall performance in a complex system. The construction of the FRAM model facilitated an understanding of the complexity of interactions within the current system, how system conditions influence everyday sepsis management and how proposed interventions would work within the context of the current system. This directed the design of a multi-component improvement intervention that organisations could locally adapt and implement with the aim of improving overall system functioning and performance to improve sepsis management.


Assuntos
Atenção à Saúde/normas , Sepse/terapia , Humanos , Atenção Primária à Saúde , Sepse/patologia
4.
Clin Gastroenterol Hepatol ; 15(1): 25-36.e27, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27392760

RESUMO

BACKGROUND & AIMS: This systematic review investigated the efficacy and the effectiveness of biologic drugs in extraintestinal manifestations (EIMs) in inflammatory bowel disease (IBD). METHODS: Literature search was conducted in PubMed, Embase, and Cochrane until October 2015. Main inclusion criteria were adults with IBD, use of a biologic drug, evolution of EIMs, interventional study, or non-interventional study. RESULTS: Nine interventional studies (2 randomized controlled trials [N = 797], 7 open label trials [N = 1143], and 13 non-interventional studies [N = 914]) were included. Tumor necrosis factor (TNF) antagonists achieved complete response for pyoderma gangrenosum in 21%-25% of patients in interventional studies and in 92%-100% patients in non-interventional studies, with similar results for other cutaneous manifestations such as erythema nodosum or stomatitis. Adalimumab significantly reduced the prevalence of anemia vs placebo after 56 weeks in 1 randomized controlled trial. In 2 non-interventional studies, anti-TNF therapy improved anemia in the short-term (67%) and in the long-term (34%). Complete response after anti-TNF treatment was reported in interventional studies, including arthralgia (reduction in prevalence from 47.1% to 26.8% in the mid-term in 1 open label trial) and arthritis (reduction in prevalence from 8.7% to 2.1% and from 58% to 12.5% in 2 open label trials). Anti-TNFs were beneficial for a majority of patients with ocular manifestations. Infliximab was associated with improved outcomes in bone formation and bone mineral density. CONCLUSIONS: Anti-TNFs appear to be effective alternatives for certain EIMs associated with IBD including musculoskeletal, cutaneous, and ocular manifestations, and some beneficial effect may be obtained in metabolic bone disease and on hematologic or vascular EIMs.


Assuntos
Produtos Biológicos/uso terapêutico , Fatores Imunológicos/uso terapêutico , Doenças Inflamatórias Intestinais/tratamento farmacológico , Fator de Necrose Tumoral alfa/antagonistas & inibidores , Humanos , Resultado do Tratamento
5.
BMJ Qual Saf ; 26(4): 335-342, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-27029536

RESUMO

OBJECTIVES: To report the implementation of a trigger review method (TRM) in primary care, with a particular focus on its impact on patient safety-related findings. DESIGN: Cross-sectional structured review of random samples (n=25) of electronic records of 'high-risk' patient groups conducted twice per year (each for a retrospective review period of 3 months). SETTING: 274 general practices in two regions of Scotland. INTERVENTION: Contractual incentivisation of TRM implementation. MAIN OUTCOME MEASURES: Practice participation rate; characteristics of patient safety incidents (PSIs), for example, their prevalence, type, perceived severity and preventability; and actions or intended actions undertaken during and after trigger reviews. RESULTS: 274 of 318 eligible practices (86.2%) returned 536 TRM Summary Reports, which outlined findings from reviews of 13 351 electronic patient records. 1887 (14.1%) PSIs were recorded, with a mean of 3.5 (536/1887) per Summary Report (SD±1.6). Of these, 830 (44.0%) were judged to have caused mild to moderate harm, with 262 (13.9%) cases resulting in more severe harm. A total of 852 PSIs (46.2%) were rated as preventable or potentially preventable. In 459 Summary Reports (85.6%), reviewers indicated implementing one or more improvement actions during the actual TRM process; and 2177 actions after completion of the TRM process (mean 4.1 (SD±3.3) actions per review). CONCLUSIONS: The great majority of clinician reviewers 'successfully' applied the TRM, uncovering important but previously undetected PSIs, which prompted care teams to take action during and after the trigger reviews. The method and data generated have the potential to drive improvements in related care processes at the practice, regional and national health system level. TRM arguably increased 'ownership' of the safety challenge and clinician engagement in implementing their solutions to specific problems identified. Our results suggest that the TRM has potential as a feasible, pragmatic approach to improving primary care safety and quality.


Assuntos
Segurança do Paciente/normas , Melhoria de Qualidade , Estudos Transversais , Medicina Geral , Humanos , Auditoria Médica , Erros Médicos/prevenção & controle , Avaliação de Resultados em Cuidados de Saúde , Estudos Retrospectivos , Escócia
6.
J Lipid Res ; 53(3): 529-539, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22246918

RESUMO

Z-Guggulsterone is a major ingredient in the Indian traditional hypolipidemic remedy guggul. A study in mice has established that its hypolipidemic effect involves the farnesoid X receptor (FXR), presumably by acting as an antagonist of this receptor. It is generally assumed that the antagonism leads to induction of cytochrome P450 7A1 (CYP7A1), the rate-limiting enzyme converting free cholesterol to bile acids. In this study, we tested whether Z-guggulsterone indeed induces human CYP7A1. In addition, the expression of cholesteryl ester hydrolase CES1 and bile salt export pump (BSEP) was monitored. Contrary to the general assumption, Z-guggulsterone did not induce CYP7A1. Instead, this phytosterol significantly induced CES1 and BSEP through transactivation. Z-Guggulsterone underwent metabolism by CYP3A4, and the metabolites greatly increased the induction potency on BSEP but not on CES1. BSEP induction favors cholesterol elimination, whereas CES1 involves both elimination and retention (probably when excessively induced). Interestingly, clinical trials reported the hypolipidemic response rates from 18% to 80% and showed that higher dosages actually increased VLDL cholesterol. Our findings predict that better hypolipidemic outcomes likely occur in individuals who have a relatively higher capacity of metabolizing Z-guggulsterone with moderate CES1 induction, a scenario possibly achieved by lowering the dosing regimens.


Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Hidrolases de Éster Carboxílico/metabolismo , Hepatócitos/metabolismo , Hipolipemiantes/farmacologia , Pregnenodionas/farmacologia , Membro 11 da Subfamília B de Transportadores de Cassetes de Ligação de ATP , Transportadores de Cassetes de Ligação de ATP/genética , Animais , Hidrolases de Éster Carboxílico/genética , Células Cultivadas , Colesterol 7-alfa-Hidroxilase/genética , Colesterol 7-alfa-Hidroxilase/metabolismo , Citocromo P-450 CYP3A/genética , Citocromo P-450 CYP3A/metabolismo , Hepatócitos/efeitos dos fármacos , Masculino , Camundongos , Regiões Promotoras Genéticas/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa
7.
Mol Ther Nucleic Acids ; 1: e9, 2012 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-23344724

RESUMO

Mice deficient for the cellular prion protein (PrP(C)) do not develop prion disease; accordingly, gene-based strategies to diminish PrP(C) expression are of interest. We synthesized a series of chemically modified antisense oligonucleotides (ASOs) targeted against mouse Prnp messenger RNA (mRNA) and identified those that were most effective in decreasing PrP(C) expression. Those ASOs were also evaluated in scrapie-infected cultured cells (ScN2a) for their efficacy in diminishing the levels of the disease-causing prion protein (PrP(Sc)). When the optimal ASO was infused intracerebrally into FVB mice over a 14-day period beginning 1 day after infection with the Rocky Mountain Laboratory (RML) strain of mouse prions, a prolongation of the incubation period of almost 2 months was observed. Whether ASOs can be used to develop an effective therapy for patients dying of Creutzfeldt-Jakob disease remains to be established.

8.
FEBS Lett ; 585(4): 671-6, 2011 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-21266177

RESUMO

RNA processing is vital for the high fidelity and diversity of eukaryotic transcriptomes and the encoded proteomes. However, control of RNA processing is not fully established. Σ RNA is a class of conserved large non-coding RNAs (murine Hepcarcin; human MALAT-1) up-regulated in carcinomas. Using antisense technology, we identified that RNA post-transcriptional modification is the most significant global function of Σ RNA. Specifically, processing of the pre-mRNAs of genes including Tissue Factor and Endoglin was altered by hydrolysis of Σ RNA/MALAT-1. These results support the hypothesis that Σ RNA/MALAT-1 is a regulatory molecule exerting roles in RNA post-transcriptional modification.


Assuntos
Carcinoma/metabolismo , Processamento Pós-Transcricional do RNA , RNA Neoplásico/metabolismo , RNA não Traduzido/metabolismo , Processamento Alternativo , Animais , Antígenos CD/genética , Antígenos CD/metabolismo , Células Cultivadas , Endoglina , Perfilação da Expressão Gênica , Regulação Neoplásica da Expressão Gênica , Células HeLa , Humanos , Proteínas Nucleares/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , Oligonucleotídeos Antissenso , Precursores de RNA/metabolismo , RNA Longo não Codificante , RNA não Traduzido/antagonistas & inibidores , RNA não Traduzido/genética , Proteínas de Ligação a RNA/metabolismo , Ratos , Receptores de Superfície Celular/genética , Receptores de Superfície Celular/metabolismo , Fatores de Processamento de Serina-Arginina , Tromboplastina/genética , Tromboplastina/metabolismo
9.
Blood ; 116(22): 4684-92, 2010 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-20807891

RESUMO

Existing anticoagulants effectively inhibit the activity of coagulation factors of the extrinsic and common pathway but have substantial limitations and can cause severe bleeding complications. Here we describe a novel therapeutic approach to thrombosis treatment. We have developed and characterized the efficacy and safety of selective second-generation antisense oligonucleotides (ASOs) targeting coagulation factor XI (FXI), a member of the intrinsic coagulation pathway. Systemic treatment of mice with FXI ASO led to a potent, specific, and dose-dependent reduction of FXI mRNA levels in the liver with corresponding reductions in plasma levels of FXI protein and activity. FXIASO treatment produced potent, dose-dependent antithrombotic activity in various venous and arterial thrombosis models, comparable with warfarin or enoxaparin. However, unlike warfarin or enoxaparin, FXI inhibition did not cause bleeding. Coadministration of FXI ASO with enoxaparin or the antiplatelet drug clopidogrel produced improved antithrombotic activity without increased bleeding. Finally, plasma-derived FXI concentrate was shown to effectively and rapidly reverse the anticoagulant effect of FXI antisense therapy. These results support the concept that inhibition of FXI through antisense therapy might serve as a new and effective strategy for the treatment and prevention of venous thromboembolism with improved specificity and safety.


Assuntos
Anticoagulantes/uso terapêutico , Fator XI/antagonistas & inibidores , Fator XI/metabolismo , Oligonucleotídeos Antissenso/uso terapêutico , Trombose/tratamento farmacológico , Animais , Anticoagulantes/efeitos adversos , Anticoagulantes/farmacologia , Clopidogrel , Combinação de Medicamentos , Enoxaparina/uso terapêutico , Hemorragia/etiologia , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Oligonucleotídeos Antissenso/efeitos adversos , Oligonucleotídeos Antissenso/farmacologia , Ticlopidina/análogos & derivados , Ticlopidina/uso terapêutico
10.
Toxicol Appl Pharmacol ; 249(3): 208-16, 2010 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-20869979

RESUMO

Numerous studies support the fact that a genetically diverse mouse population may be useful as an animal model to understand and predict toxicity in humans. We hypothesized that cultures of hepatocytes obtained from a large panel of inbred mouse strains can produce data indicative of inter-individual differences in in vivo responses to hepato-toxicants. In order to test this hypothesis and establish whether in vitro studies using cultured hepatocytes from genetically distinct mouse strains are feasible, we aimed to determine whether viable cells may be isolated from different mouse inbred strains, evaluate the reproducibility of cell yield, viability and functionality over subsequent isolations, and assess the utility of the model for toxicity screening. Hepatocytes were isolated from 15 strains of mice (A/J, B6C3F1, BALB/cJ, C3H/HeJ, C57BL/6J, CAST/EiJ, DBA/2J, FVB/NJ, BALB/cByJ, AKR/J, MRL/MpJ, NOD/LtJ, NZW/LacJ, PWD/PhJ and WSB/EiJ males) and cultured for up to 7 days in traditional 2-dimensional culture. Cells from B6C3F1, C57BL/6J, and NOD/LtJ strains were treated with acetaminophen, WY-14,643 or rifampin and concentration-response effects on viability and function were established. Our data suggest that high yield and viability can be achieved across a panel of strains. Cell function and expression of key liver-specific genes of hepatocytes isolated from different strains and cultured under standardized conditions are comparable. Strain-specific responses to toxicant exposure have been observed in cultured hepatocytes and these experiments open new opportunities for further developments of in vitro models of hepatotoxicity in a genetically diverse population.


Assuntos
Hepatócitos/efeitos dos fármacos , Camundongos Endogâmicos , Modelos Animais , Testes de Toxicidade , Acetaminofen/toxicidade , Analgésicos não Narcóticos/toxicidade , Animais , Antibióticos Antituberculose/toxicidade , Sobrevivência Celular/efeitos dos fármacos , Expressão Gênica/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Pirimidinas/toxicidade , Rifampina/toxicidade
11.
J Med Chem ; 53(4): 1636-50, 2010 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-20108935

RESUMO

To identify chemistries and strategies to improve the potency of MOE second generation ASOs, we have evaluated gapmer antisense oligonucleotides containing BNAs having N-O bonds. These modifications include N-MeO-amino BNA, N-Me-aminooxy BNA, 2',4'-BNA(NC)[NMe], and 2',4'-BNA(NC) bridged nucleoside analogues. These modifications provided increased thermal stability and improved in vitro activity compared to the corresponding ASO containing the MOE modification. Additionally, ASOs containing N-MeO-amino BNA, N-Me-aminooxy BNA, and 2',4'-BNA(NC)[NMe] modifications showed improved in vivo activity (>5-fold) compared to MOE ASO. Importantly, toxicity parameters, such as AST, ALT, liver, kidney, and body weights, were found to be normal for N-MeO-amino BNA, N-Me-aminooxy BNA, and 2',4'-BNA(NC)[NMe] ASO treated animals. The data generated in these experiments suggest that N-MeO-amino BNA, N-Me-aminooxy BNA, and 2',4'-BNA(NC)[NMe] are useful modifications for applications in both antisense and other oligonucleotide based drug discovery efforts.


Assuntos
Oligorribonucleotídeos Antissenso/síntese química , Alanina Transaminase/metabolismo , Animais , Aspartato Aminotransferases/metabolismo , Peso Corporal/efeitos dos fármacos , Linhagem Celular , Estabilidade de Medicamentos , Temperatura Alta , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Conformação Molecular , Desnaturação de Ácido Nucleico , Ácidos Nucleicos Heteroduplexes/química , Oligorribonucleotídeos Antissenso/farmacologia , Oligorribonucleotídeos Antissenso/toxicidade , Tamanho do Órgão/efeitos dos fármacos , PTEN Fosfo-Hidrolase/biossíntese , PTEN Fosfo-Hidrolase/genética , RNA Mensageiro/biossíntese , Relação Estrutura-Atividade
12.
Drug Metab Lett ; 2(3): 176-83, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-19356090

RESUMO

Aldehyde oxidase (AO) is a cytosolic enzyme that contributes to the Phase I metabolism of xenobiotics in human and preclinical species. We compared AO activity in cytosol and cryopreserved hepatocytes from human, monkey, rat and mouse livers to assess species differences. We also evaluated possible species differences in drug interactions using seven drugs known to inhibit human cytosolic AO i.e. raloxifene, perphenazine, menadione, maprotiline, ketoconazole, erythromycin, and estradiol. AO activity was measured using the formation of vanillic acid from vanillin. The rate of vanillic acid formation was 2 +/- 0.2 nmol/min/mg in human liver cytosol and 0.79 +/- 0.45 nmol/min/million cells in cryopreserved human hepatocytes. AO activity (V(max,app)) was highest in monkey and lowest in rat. Mouse liver cytosol had the lowest K(m,app) (1.44 +/- 0.16 microM) and highest intrinsic clearance (8.97 ml/min/mg) and rat liver cytosol the highest K(m,app) (10.9 +/- 1.2 microM) and lowest intrinsic clearance (0.47 ml/min/mg). There was a 4.25-fold difference in AO activity between the 5 human hepatocyte preparations. Drug interaction studies with the seven marketed drugs revealed marked species-specific inhibition. Our data indicates major differences in the rate of AO metabolism, and inhibition of AO across species, indicating that results from animal studies cannot be safely extrapolated to humans. Cryopreserved hepatocytes and cytosolic fractions from animals and humans provide qualitatively similar data within the species.


Assuntos
Aldeído Oxidase/metabolismo , Citosol/enzimologia , Inibidores Enzimáticos/farmacologia , Hepatócitos/enzimologia , Aldeído Oxidase/antagonistas & inibidores , Animais , Benzaldeídos/metabolismo , Criopreservação , Citosol/efeitos dos fármacos , Interações Medicamentosas , Feminino , Hepatócitos/efeitos dos fármacos , Humanos , Macaca fascicularis , Masculino , Camundongos , Ratos , Ratos Sprague-Dawley , Especificidade da Espécie , Ácido Vanílico/metabolismo
13.
J Pharmacol Exp Ther ; 319(3): 1477-84, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16966469

RESUMO

Oseltamivir is the main medicine recommended by the World Health Organization in anticipation of next influenza pandemic. This anti-influenza viral agent is an ester prodrug, and the antiviral activity is achieved by its hydrolytic metabolite: oseltamivir carboxylate. In this study, we report that the hydrolytic activation is catalyzed by carboxylesterase human carboxylesterase (HCE) 1. Liver microsomes rapidly hydrolyzed oseltamivir, but no hydrolysis was detected with intestinal microsomes or plasma. The overall rate of the hydrolysis varied among individual liver samples and was correlated well with the level of HCE1. Recombinant HCE1 but not HCE2 hydrolyzed this prodrug and produced similar kinetic parameters as the liver microsomes. Several HCE1 natural variants differed from the wild-type enzyme on the hydrolysis of oseltamivir. In the presence of antiplatelet agent clopidogrel, the hydrolysis of oseltamivir was inhibited by as much as 90% when the equal concentration was assayed. Given the fact that hydrolysis of oseltamivir is required for its therapeutic activity, concurrent use of both drugs would inhibit the activation of oseltamivir, thus making this antiviral agent therapeutically inactive. This is epidemiologically of significance because people who receive oseltamivir and clopidogrel simultaneously may maintain susceptibility to influenza infection or a source of spreading influenza virus if already infected.


Assuntos
Antivirais/metabolismo , Hidrolases de Éster Carboxílico/metabolismo , Oseltamivir/metabolismo , Inibidores da Agregação Plaquetária/farmacologia , Ticlopidina/análogos & derivados , Hidrolases de Éster Carboxílico/antagonistas & inibidores , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Clopidogrel , Interações Medicamentosas , Humanos , Hidrólise , Espectrometria de Massas , Microssomos/efeitos dos fármacos , Microssomos/metabolismo , Mutagênese Sítio-Dirigida , Ticlopidina/farmacologia , Transfecção
14.
J Pharmacol Exp Ther ; 319(3): 1467-76, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16943252

RESUMO

Aspirin (acetylsalicylic acid) and clopidogrel are two major antithrombogenic agents that are widely used for the treatment and prevention of cerebro- and cardiovascular conditions such as stroke. Combined use produces enhanced therapeutic effect. Aspirin and clopidogrel both are esters, and hydrolysis leads to decreased or inactivated therapeutic activity. The aim of the study was to determine whether aspirin and clopidogrel are hydrolyzed by the same enzyme(s), thus reciprocally prolonging the antithrombogenic activity. To test this possibility, microsomes from the liver and intestine were assayed for the hydrolysis of aspirin and clopidogrel. In contrary to the hypothesis, aspirin and clopidogrel were hydrolyzed in a tissue-differential manner. Liver microsomes hydrolyzed both drugs, whereas intestinal microsomes hydrolyzed aspirin only. Consistent with the tissue distribution of two carboxylesterases human carboxylesterase (HCE) 1 and HCE2, recombinant HCE1 hydrolyzed clopidogrel, whereas recombinant HCE2 hydrolyzed aspirin. In addition, hydrolysis of clopidogrel among liver samples was correlated well with the level of HCE1, and hydrolysis of aspirin with HCE2. Certain natural variants differed from the wild-type enzymes on the hydrolysis of aspirin or clopidogrel. In the presence of ethyl alcohol, clopidogrel is converted to ethyl clopidogrel. Carboxylesterases are important pharmacological determinants for drugs containing ester linkages and exhibit a large interindividual variation. The isoform-specific hydrolysis of aspirin and clopidogrel suggests that these two antithrombogenic agents may have pharmacokinetic interactions with different sets of ester drugs, and the altered hydrolysis by polymorphic mutants provides a molecular explanation to the interindividual variation.


Assuntos
Aspirina/metabolismo , Hidrolases de Éster Carboxílico/metabolismo , Depressores do Sistema Nervoso Central/farmacologia , Etanol/farmacologia , Inibidores da Agregação Plaquetária/metabolismo , Ticlopidina/análogos & derivados , Animais , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Cromatografia Líquida de Alta Pressão , Clopidogrel , Ésteres/metabolismo , Humanos , Hidrólise , Técnicas In Vitro , Mucosa Intestinal/metabolismo , Microssomos/metabolismo , Microssomos Hepáticos/metabolismo , Mutagênese Sítio-Dirigida , Ratos , Ticlopidina/metabolismo , Transfecção
15.
Cancer Chemother Pharmacol ; 55(3): 213-21, 2005 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-15592840

RESUMO

OSI-7836 (4'-thio-beta-D-arabinofuranosylcytosine) is a novel nucleoside analog in phase I clinical development for the treatment of cancer. As with other nucleoside analogs, the proposed mechanism of action involves phosphorylation to the triphosphate form followed by incorporation into cellular DNA, leading to cell death. This hypothesis has been examined by measuring and comparing the incorporation of ara-C, OSI-7836, and gemcitabine (dFdC) into DNA of cultured cells and by investigating the role of deoxycytidine kinase in OSI-7836 toxicity. We report here additional studies in which the role of cell cycling on OSI-7836 toxicity was investigated and incorporation of OSI-7836 into DNA of xenograft tumors measured. The role of the cell cycle was examined by comparing the toxicity of OSI-7836 in A549 NSCLC cells that were either in log phase growth or had reached confluence. A novel validated LC-MS/MS assay was developed to quantify the concentrations of OSI-7836 in DNA from Calu-6 and H460 human tumor xenografts in mice. Results showed that apoptosis induced by OSI-7836 was markedly greater in cycling cells than in confluent non-cycling cells despite only a modest increase in intracellular OSI-7836 triphosphate concentration. The LC-MS/MS assay developed to measure OSI-7836 incorporation into DNA had an on-column detection limit of 0.25 fmol, a quantification limit of 0.5 fmol, and a sensitivity of approximately 0.1 pmol OSI-7836/micromol dThy. Concentrations of OSI-7836 in splenic DNA (0.4 pmol OSI-7836/micromol dThy) averaged fivefold less than the average concentration in Calu-6 and H460 xenograft DNA (3.0 pmol OSI-7836/micromol dThy) following a 400 mg/kg dose of OSI-7836. Concentrations of OSI-7836 in Calu-6 tumor DNA isolated 24 h following a dose of 400, 1000, or 1600 mg OSI-7836/kg were approximately 1.3, 1 and 1.3 pmol OSI-7836/micromol dThy, respectively. Concentrations of OSI-7836 in DNA from H460 and Calu-6 xenografts did not appear to increase during repeated administration of 400 mg OSI-7836/kg on days 1, 4, 7, and 10. The majority of OSI-7836 in DNA from Calu-6 and H460 tumors of mice dosed with 1600 mg/kg was located at internal nucleotide linkages, similar to dFdC and ara-C. In conclusion, cell cycling studies supported the hypothesis that OSI-7836 cytotoxicity is dependent upon DNA synthesis. A validated LC-MS/MS assay was developed that could quantify OSI-7836 in DNA from tissues. The assay was used to show that OSI-7836 was incorporated in internal linkages in tumor DNA in a manner that was dose-independent at the doses tested and did not appear to accumulate during repeated dosing. The results suggest that if DNA incorporation is a toxic event, the relationships between administered dose, DNA incorporation, and toxicity are complex.


Assuntos
Antineoplásicos/metabolismo , Arabinonucleosídeos/metabolismo , DNA de Neoplasias/metabolismo , Animais , Ciclo Celular , Replicação do DNA , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Humanos , Camundongos , Transplante de Neoplasias , Transplante Heterólogo , Células Tumorais Cultivadas
16.
Dyn Med ; 3(1): 1, 2004 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-14728716

RESUMO

BACKGROUND: The purpose of this study was to measure blood flow in the carotid and femoral arteries, heart rate and blood pressure in response to postural challenge in older adults. A second purpose was to determine if older men and women have different cardiovascular responses to a postural challenge such as tilt. METHODS: Thirty-seven healthy elderly men and women participated in this study (69-82 years old). All subjects had similar physical activity levels. Postural challenge was induced by a 60 degrees tilt at the level of the waist. Continuous carotid blood flow and femoral blood flow was measured with Doppler ultrasound. RESULTS: Carotid blood flow was significantly reduced 17% in both men and women immediately after tilt (p < 0.001), and by 3.2% two minutes after tilt (p < 0.001). Femoral blood flow decreased 59.4% in men and 61% in women immediately after tilt (p < 0.001), and remained significantly decreased two minutes after tilt by 21% (p <0.001). Heart rate increased by 15% in men (p < 0.001), and 26% in women immediately after the tilt (p < 0.001). Heart rate returned to resting values within two minutes in both men and women. Response to tilt was not significantly related to self-report physical activity levels or to six-minute walk time. CONCLUSION: A postural challenge induced larger changes in the femoral artery compared to the carotid artery. There were no differences between men and women to a tilt table test except for differences in heart rate response. There was no difference in the blood flow responses to postural challenge with physical activity level or between healthy older men and women.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...