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1.
Pharmacogenomics J ; 18(2): 215-226, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-28719597

RESUMO

Thiazide diuretics, commonly used antihypertensives, may cause QT interval (QT) prolongation, a risk factor for highly fatal and difficult to predict ventricular arrhythmias. We examined whether common single-nucleotide polymorphisms (SNPs) modified the association between thiazide use and QT or its component parts (QRS interval, JT interval) by performing ancestry-specific, trans-ethnic and cross-phenotype genome-wide analyses of European (66%), African American (15%) and Hispanic (19%) populations (N=78 199), leveraging longitudinal data, incorporating corrected standard errors to account for underestimation of interaction estimate variances and evaluating evidence for pathway enrichment. Although no loci achieved genome-wide significance (P<5 × 10-8), we found suggestive evidence (P<5 × 10-6) for SNPs modifying the thiazide-QT association at 22 loci, including ion transport loci (for example, NELL1, KCNQ3). The biologic plausibility of our suggestive results and simulations demonstrating modest power to detect interaction effects at genome-wide significant levels indicate that larger studies and innovative statistical methods are warranted in future efforts evaluating thiazide-SNP interactions.


Assuntos
Envelhecimento/genética , Etnicidade/genética , Genômica/tendências , Frequência Cardíaca/genética , Farmacogenética/tendências , Inibidores de Simportadores de Cloreto de Sódio/farmacologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/efeitos dos fármacos , Envelhecimento/etnologia , Estudos de Coortes , Eletrocardiografia/efeitos dos fármacos , Eletrocardiografia/tendências , Feminino , Genômica/métodos , Frequência Cardíaca/efeitos dos fármacos , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Farmacogenética/métodos , Polimorfismo de Nucleotídeo Único/efeitos dos fármacos , Polimorfismo de Nucleotídeo Único/genética
2.
Geophys Res Lett ; 44(10): 5104-5112, 2017 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-29950746

RESUMO

Volcanic eruptions have global climate impacts, but their effect on the hydrologic cycle is poorly understood. We use a modified version of superposed epoch analysis, an eruption year list collated from multiple datasets, and seasonal paleoclimate reconstructions (soil moisture, precipitation, geopotential heights, and temperature) to investigate volcanic forcing of spring and summer hydroclimate over Europe and the Mediterranean over the last millennium. In the western Mediterranean, wet conditions occur in the eruption year and the following 3 years. Conversely, northwestern Europe and the British Isles experience dry conditions in response to volcanic eruptions, with the largest moisture deficits in post-eruption years 2 and 3. The precipitation response occurs primarily in late spring and early summer (April-July), a pattern that strongly resembles the negative phase of the East Atlantic Pattern. Modulated by this mode of climate variability, eruptions force significant, widespread, and heterogeneous hydroclimate responses across Europe and the Mediterranean.

3.
Mol Psychiatry ; 20(2): 183-92, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25644384

RESUMO

General cognitive function is substantially heritable across the human life course from adolescence to old age. We investigated the genetic contribution to variation in this important, health- and well-being-related trait in middle-aged and older adults. We conducted a meta-analysis of genome-wide association studies of 31 cohorts (N=53,949) in which the participants had undertaken multiple, diverse cognitive tests. A general cognitive function phenotype was tested for, and created in each cohort by principal component analysis. We report 13 genome-wide significant single-nucleotide polymorphism (SNP) associations in three genomic regions, 6q16.1, 14q12 and 19q13.32 (best SNP and closest gene, respectively: rs10457441, P=3.93 × 10(-9), MIR2113; rs17522122, P=2.55 × 10(-8), AKAP6; rs10119, P=5.67 × 10(-9), APOE/TOMM40). We report one gene-based significant association with the HMGN1 gene located on chromosome 21 (P=1 × 10(-6)). These genes have previously been associated with neuropsychiatric phenotypes. Meta-analysis results are consistent with a polygenic model of inheritance. To estimate SNP-based heritability, the genome-wide complex trait analysis procedure was applied to two large cohorts, the Atherosclerosis Risk in Communities Study (N=6617) and the Health and Retirement Study (N=5976). The proportion of phenotypic variation accounted for by all genotyped common SNPs was 29% (s.e.=5%) and 28% (s.e.=7%), respectively. Using polygenic prediction analysis, ~1.2% of the variance in general cognitive function was predicted in the Generation Scotland cohort (N=5487; P=1.5 × 10(-17)). In hypothesis-driven tests, there was significant association between general cognitive function and four genes previously associated with Alzheimer's disease: TOMM40, APOE, ABCG1 and MEF2C.


Assuntos
Transtornos Cognitivos/genética , Cognição/fisiologia , Predisposição Genética para Doença/genética , Proteína HMGN1/genética , Polimorfismo de Nucleotídeo Único/genética , Idoso , Idoso de 80 Anos ou mais , Aterosclerose/complicações , Transtornos Cognitivos/etiologia , Estudos de Coortes , Feminino , Estudo de Associação Genômica Ampla , Humanos , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Fenótipo , Escócia
4.
Eur J Clin Pharmacol ; 72(4): 431-7, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26686871

RESUMO

PURPOSE: In pharmacogenetic research, genetic variation in non-responders and high responders is compared with the aim to identify the genetic loci responsible for this variation in response. However, an important question is whether the non-responders are truly biologically non-responsive or actually non-adherent? Therefore, the aim of this study was to describe, within the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER), characteristics of both non-responders and high responders of statin treatment in order to possibly discriminate non-responders from non-adherers. METHODS: Baseline characteristics of non-responders to statin therapy (≤10 % LDL-C reduction) were compared with those of high responders (>40 % LDL-C reduction) through a linear regression analysis. In addition, pharmacogenetic candidate gene analysis was performed to show the effect of excluding non-responders from the analysis. RESULTS: Non-responders to statin therapy were younger (p = 0.001), more often smoked (p < 0.001), had a higher alcohol consumption (p < 0.001), had lower LDL cholesterol levels (p < 0.001), had a lower prevalence of hypertension (p < 0.001), and had lower cognitive function (p = 0.035) compared to subjects who highly responded to pravastatin treatment. Moreover, excluding non-responders from pharmacogenetic studies yielded more robust results, as standard errors decreased. CONCLUSION: Our results suggest that non-responders to statin therapy are more likely to actually be non-adherers, since they have more characteristics that are viewed as indicators of high self-perceived health and low disease awareness, possibly making the subjects less adherent to study medication. We suggest that in pharmacogenetic research, extreme non-responders should be excluded to overcome the problem that non-adherence is investigated instead of non-responsiveness.


Assuntos
Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Idoso , Idoso de 80 Anos ou mais , LDL-Colesterol/sangue , Feminino , Variação Genética/genética , Humanos , Masculino , Farmacogenética/métodos , Testes Farmacogenômicos , Pravastatina/uso terapêutico , Estudos Prospectivos , Ensaios Clínicos Controlados Aleatórios como Assunto , Risco , Resultado do Tratamento
5.
Pharmacogenomics J ; 14(1): 6-13, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23459443

RESUMO

Variability in response to drug use is common and heritable, suggesting that genome-wide pharmacogenomics studies may help explain the 'missing heritability' of complex traits. Here, we describe four independent analyses in 33 781 participants of European ancestry from 10 cohorts that were designed to identify genetic variants modifying the effects of drugs on QT interval duration (QT). Each analysis cross-sectionally examined four therapeutic classes: thiazide diuretics (prevalence of use=13.0%), tri/tetracyclic antidepressants (2.6%), sulfonylurea hypoglycemic agents (2.9%) and QT-prolonging drugs as classified by the University of Arizona Center for Education and Research on Therapeutics (4.4%). Drug-gene interactions were estimated using covariable-adjusted linear regression and results were combined with fixed-effects meta-analysis. Although drug-single-nucleotide polymorphism (SNP) interactions were biologically plausible and variables were well-measured, findings from the four cross-sectional meta-analyses were null (Pinteraction>5.0 × 10(-8)). Simulations suggested that additional efforts, including longitudinal modeling to increase statistical power, are likely needed to identify potentially important pharmacogenomic effects.


Assuntos
Efeitos Colaterais e Reações Adversas Relacionados a Medicamentos/genética , Interação Gene-Ambiente , Síndrome do QT Longo/genética , Farmacogenética , Polimorfismo de Nucleotídeo Único/genética , Característica Quantitativa Herdável , Simulação por Computador , Estudos Transversais , Eletrocardiografia , Estudo de Associação Genômica Ampla , Humanos , Modelos Lineares , Cadeias de Markov , População Branca/genética
6.
Respiration ; 81(1): 18-25, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-20134147

RESUMO

BACKGROUND: Arterial blood gases (ABGs) are often sampled incorrectly, leading to a 'mixed' or venous sample. Delays in analysis and air contamination are common. OBJECTIVES: We measured the effects of these errors in patients with chronic obstructive pulmonary disease (COPD) exacerbations and controls. METHODS: Arterial and venous samples were analyzed from 30 patients with COPD exacerbation and 30 controls. Venous samples were analysed immediately and arterial samples separated into non-air-contaminated and air-contaminated specimens and analysed at 0, 30, 60, 90 and 180 min. RESULTS: Mean venous pH was 7.371 and arterial pH was 7.407 (p < 0.0001). There was a correlation between venous and arterial pH (r = 0.5347, p < 0.0001). The regression equation to predict arterial pH was: arterial pH = 4.2289 + 0.43113 · venous pH. There were no clinically significant differences in arterial PO2 associated with analysis delay. A statistically significant decline in pH was detected at 30 min in patients with COPD exacerbation (p = 0.0042) and 90 min in controls (p < 0.0001). A clinically significant decline in pH emerged at 73 min in patients with COPD exacerbation and 87 min in controls. Air contamination was associated with a clinically significant increase in PO2 in all samples, including those that were immediately analyzed. CONCLUSIONS: Arterial and venous pH differ significantly. Venous pH cannot accurately replace arterial pH. Temporal delays in ABG analysis result in a significant decline in measured pH. ABGs should be analysed within 30 min. Air contamination leads to an immediate increase in measured PO2, indicating that air-contaminated ABGs should be discarded.


Assuntos
Erros de Diagnóstico/prevenção & controle , Doença Pulmonar Obstrutiva Crônica , Idoso , Idoso de 80 Anos ou mais , Poluição do Ar , Artérias/metabolismo , Gasometria/normas , Procedimentos Clínicos/normas , Progressão da Doença , Feminino , Humanos , Concentração de Íons de Hidrogênio , Irlanda , Laboratórios Hospitalares/normas , Masculino , Pessoa de Meia-Idade , Doença Pulmonar Obstrutiva Crônica/sangue , Doença Pulmonar Obstrutiva Crônica/diagnóstico , Padrões de Referência , Veias/metabolismo
7.
Diabetologia ; 52(2): 235-9, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19030842

RESUMO

AIMS/HYPOTHESIS: The aim of this prospective study was to determine whether circulating intercellular adhesion molecule (ICAM) 1, as a potential surrogate of 'endothelial activation', is more strongly associated with risk of vascular events than with incident diabetes. METHODS: We related baseline ICAM-1 levels to vascular events (866 CHD and stroke events in 5,685 participants) and incident diabetes (292 in 4,945 without baseline diabetes) in the elderly over 3.2 years of follow-up. RESULTS: ICAM-1 levels correlated positively with triacylglycerol but negatively with LDL- and HDL-cholesterol. ICAM-1 levels were higher in those who developed diabetes (388.6 +/- 1.42 vs 369.4 +/- 1.39 ng/ml [mean+/-SD], p = 0.011) and remained independently associated with new-onset diabetes (HR 1.84, 95% CI 1.26-2.69, p = 0.0015 per unit increase in log[ICAM-1] after adjusting for classical risk factors and C-reactive protein). By contrast, ICAM-1 levels were not significantly (p = 0.40) elevated in those who had an incident vascular event compared with those who remained event-free, and corresponding adjusted risk associations were null (HR 0.98, 95% CI 0.80-1.22, p = 0.89) in analyses adjusted for other risk factors. CONCLUSIONS/INTERPRETATION: We show that elevated ICAM-1 levels are associated with risk of incident diabetes in the elderly at risk, despite no association with incident cardiovascular disease risk. We suggest that perturbations in circulating ICAM-1 levels are aligned more towards diabetes risk.


Assuntos
Diabetes Mellitus/epidemiologia , Endotélio Vascular/fisiologia , Molécula 1 de Adesão Intercelular/sangue , Infarto do Miocárdio/epidemiologia , Acidente Vascular Cerebral/epidemiologia , Idoso , Idoso de 80 Anos ou mais , Pressão Sanguínea , Colesterol/sangue , HDL-Colesterol/sangue , LDL-Colesterol/sangue , Diabetes Mellitus/sangue , Feminino , Seguimentos , Humanos , Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Incidência , Masculino , Infarto do Miocárdio/sangue , Infarto do Miocárdio/mortalidade , Pravastatina/uso terapêutico , Valor Preditivo dos Testes , Estudos Prospectivos , Fatores de Risco , Acidente Vascular Cerebral/sangue , Acidente Vascular Cerebral/mortalidade , Fatores de Tempo
8.
Science ; 258(5088): 1621-3, 1992 Dec 04.
Artigo em Inglês | MEDLINE | ID: mdl-17742529

RESUMO

Radiocarbon ages of submerged trees on landslide deposits in Lake Washington, Seattle, indicate that the most recent slides in three separate areas may have occurred simultaneously about 1000 years ago. Tree ring crossdating shows that seven bark-bearing trees from one of these recent slides and a tree 23 kilometers to the northwest in a probable tsunami deposit on the shore of Puget Sound died in the same season of the same year. The close coincidence among the most recent lake landslides, a probable tsunami, abrupt subsidence, and other possible seismic events gives evidence for a strong prehistoric earthquake in the Seattle region.

9.
Brain ; 131(Pt 4): 1069-77, 2008 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-18304957

RESUMO

Inflammation is thought to play an important role in the development of cognitive decline and dementia in old age. The interleukin-1 signalling pathway may play a prominent role in this process. The gene encoding for interleukin-1 beta-converting enzyme (ICE) is likely to influence IL-1 beta levels. Inhibition of ICE decreases the age-related increase in IL-1 beta levels and may therefore improve memory function. We assessed whether genetic variation in the ICE gene associates with cognitive function in an elderly population. All 5804 participants of the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) were genotyped for the 10643GC, 9323GA, 8996AG and 5352GA polymorphisms in the ICE gene. Cross-sectional associations between the polymorphisms and cognitive function were assessed with linear regression. Longitudinal associations between polymorphisms, haplotypes and cognitive function were assessed with linear mixed models. All associations were adjusted for sex, age, education, country, treatment with pravastatin and version of test where appropriate. Subjects carrying the variants 10643C and 5352A allele had significantly lower IL-1 beta production levels (P < 0.01). Furthermore, we demonstrated that homozygous carriers of the 10643C and the 5352A allele performed better on all executive function tests at baseline and during follow-up compared to homozygous carriers of the wild-type allele (all P < 0.02). The haplotype with two variants present (10643C and 5352A) was associated with better executive function (all P < 0.02) compared to the reference haplotype without variants. For memory function the same trend was observed, although not significant. Genetic variation in the ICE gene is associated with better performance on cognitive function and lower IL-1 beta production levels. This suggests that low levels of IL-1 beta are protective for memory and learning deficits. Inhibition of ICE may therefore be an important therapeutic target for maintaining cognitive function in old age.


Assuntos
Envelhecimento/genética , Caspase 1/genética , Cognição , Polimorfismo de Nucleotídeo Único , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/psicologia , Caspase 1/fisiologia , Estudos Transversais , Feminino , Genótipo , Haplótipos , Humanos , Interleucina-1beta/biossíntese , Desequilíbrio de Ligação , Estudos Longitudinais , Masculino , Memória , Testes Neuropsicológicos
10.
Exp Gerontol ; 43(8): 801-5, 2008 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-18504081

RESUMO

Inflammation plays a prominent role in the development of atherosclerosis, which is the most important risk factor for vascular events. Lymphotoxin-alpha (LTA) is a pro-inflammatory cytokine and is found to be expressed in atherosclerotic lesions. We investigated the association between the C804A polymorphism within the LTA gene and coronary and cerebrovascular events in 5804 participants of the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER). The primary endpoint was the combined endpoint of death from coronary heart disease, non-fatal myocardial infarction, and clinical stroke. Secondary endpoints were the coronary and cerebrovascular components separately. All associations were assessed with a Cox-proportional hazards model adjusted for sex, age, pravastatin use, and country. Our overall analysis showed a significant association between the C804A polymorphism and the primary endpoint (p = 0.03). After stratification for gender, this association was found only in males. Furthermore, we found that the association between the C804A polymorphism and the primary endpoint was mainly attributable to clinical strokes (p = 0.02). The C804A polymorphism in the LTA gene associates with clinical stroke, especially in men. But further research is warranted to confirm our results.


Assuntos
Linfotoxina-alfa/genética , Polimorfismo de Nucleotídeo Único , Acidente Vascular Cerebral/genética , Idoso , Idoso de 80 Anos ou mais , Doença das Coronárias/genética , Feminino , Frequência do Gene , Predisposição Genética para Doença , Genótipo , Heterozigoto , Humanos , Masculino , Infarto do Miocárdio/genética , Fatores de Risco , Fatores Sexuais
11.
Ann N Y Acad Sci ; 1100: 189-98, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17460178

RESUMO

Proinflammatory cytokines, like interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha), are implicated in the development of atherosclerosis. The role of anti-inflammatory cytokines, like IL-10, is largely unknown. We investigated the association of four single nucleotide polymorphisms (SNPs) in the promoter region of the IL-10 gene (4259AG, -1082GA, -592CA, and -2849GA), with coronary and cerebrovascular disease in participants of the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) trial. All associations were assessed with Cox proportional hazards models adjusted for sex, age, pravastatin use, and country. Haplotype analysis of the four SNPs showed a significant association between haplotype 4 (containing the -592A variant allele) and risk of coronary events (P = 0.019). Moreover, analysis of separate SNPs found a significant association between -2849AA carriers with incident stroke (HR (95%CI) 1.50 (1.04-2.17), P value = 0.02). Our study suggests that not only proinflammatory processes contribute to atherosclerosis, but that also anti-inflammatory cytokines may play an important role.


Assuntos
Transtornos Cerebrovasculares/genética , Variação Genética , Interleucina-10/genética , Regiões Promotoras Genéticas , Idoso , Feminino , Haplótipos , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Biológicos , Polimorfismo de Nucleotídeo Único , Pravastatina/farmacologia , Risco , Fatores de Risco
12.
Transplantation ; 41(3): 335-9, 1986 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-3513392

RESUMO

Plasma ionized calcium and citrate concentrations were measured in 11 patients undergoing liver transplantation. During the anhepatic phase of the procedure, ionized calcium concentrations fell to as low as 40% of normal, in spite of calcium supplementation. Simultaneously, citrate concentrations rose to between 20 and 100 times preoperative levels. In two patients low plasma ionized calcium concentrations were associated with hypotension that responded to calcium infusion. Intraoperative monitoring of plasma ionized calcium during liver transplantation is helpful in the rational control of the patient's calcium status.


Assuntos
Cálcio/sangue , Citratos/sangue , Transplante de Fígado , Humanos , Íons , Fígado/cirurgia , Magnésio/sangue , Potássio/sangue , Fatores de Tempo
13.
Am J Cardiol ; 59(8): 878-80, 1987 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-3825953

RESUMO

An epidemiologic screening survey was conducted in 325 male industrial workers to investigate the relation between serum total and ionized calcium concentrations and blood pressure. No relation was found. Previous reports of lower serum ionized calcium levels in hypertensive patients may be related to methodologic deficiencies both in the selection of subjects and in ionized calcium measurement. These data do not support the concept that increased blood pressure levels are related to calcium deficiency or to abnormal plasma calcium homeostasis.


Assuntos
Cálcio/sangue , Hipertensão/sangue , Adulto , Cátions Bivalentes/sangue , Humanos , Concentração de Íons de Hidrogênio , Masculino , Pessoa de Meia-Idade
14.
Am J Cardiol ; 84(10): 1192-7, 1999 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-10569329

RESUMO

The PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) is a randomized, double-blind, placebo-controlled trial designed to test the hypothesis that treatment with pravastatin will diminish risk of subsequent major vascular events in a cohort of men and women (70 to 82 years old) with preexisting vascular disease or significant risk of developing this condition. Five thousand eight hundred four men and women in addition to receiving advice on diet and smoking, have been randomized equally to treatment with 40 mg pravastatin/day or matching placebo in 3 centers (Cork, Ireland, Glasgow, Scotland, and Leiden, The Netherlands). Following an average 3.5-year intervention period, a primary assessment will be made of the influence of this therapy on major vascular events (a combination of coronary heart disease, death, nonfatal myocardial infarction, and fatal and nonfatal stroke). A number of additional analyses will also be conducted on the individual components of the primary end point, on men, on women, and on subjects with and without previous evidence of vascular disease. Finally, an assessment will be made of the effects of treatment on cognitive function, disability, hospitalization or institutionalization, vascular mortality, and all-cause mortality.


Assuntos
Anticolesterolemiantes/uso terapêutico , Pravastatina/uso terapêutico , Acidente Vascular Cerebral/prevenção & controle , Idoso , Idoso de 80 Anos ou mais , Método Duplo-Cego , Feminino , Humanos , Masculino , Estudos Prospectivos
15.
Respir Med ; 85(1): 21-5, 1991 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-2014355

RESUMO

The running cost and clinical application of a new, portable, direct-injection, high-performance, liquid chromatograph for the measurement of theophylline was compared with conventional laboratory-based analysis by studying the two methods in two parallel chest clinics. Thirty-six patients were managed with the portable method and 33 by the conventional system. They were already receiving theophylline preparations for treatment of their asthma or chronic airflow limitation. Over the 12-week period of study, the percentage of patients with levels in the therapeutic range rose from 33% to approximately 87% in both clinics, but this change was achieved in only 6 weeks using the portable system. Patients whose theophylline levels were increased into the therapeutic range had improved symptom scores as measured by visual analogue scales but we were unable to demonstrate any significant change in spirometry. The cost of the portable system compared favourably with laboratory analysis, and had the additional benefit of quicker detection of non-compliance and facility for discussion with the patients at the time of consultation.


Assuntos
Cromatografia Líquida de Alta Pressão/instrumentação , Teofilina/sangue , Adulto , Idoso , Asma/sangue , Asma/tratamento farmacológico , Asma/fisiopatologia , Economia Médica , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Espirometria , Teofilina/uso terapêutico , Fatores de Tempo
16.
Ann Clin Biochem ; 24 ( Pt 5): 488-93, 1987 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-3662399

RESUMO

A manual column-switching technique is described for the measurement of phenytoin, phenobarbitone, carbamazepine, and carbamazepine 10,11-epoxide. The analytical system is designed to be portable for use at the out-patient clinic and comprises an isocratic pump, UV detector and injection valve, together with a preparation column. Diluted plasma or serum is injected, without pre-extraction, onto a preparation column which replaces the sample loop on the injection valve. After washing unwanted material to waste, the preparation column is switched in-line with the analytical column, where separation of analytes occurs. The precision, accuracy and carryover of this extra-laboratory system are comparable with those obtained with laboratory-based immunoassay systems. Operation of the system allows the reporting of results within 5 min of sample injection and requires no specialist skills. The technique should be of particular interest to district general hospital laboratories where workload does not justify the cost of an automated HPLC system as the total capital cost is comparable to that of a portable glucose analyser. In contrast to immunoassay systems consumable costs are minimal. The equipment is easy to transport and may be used in the out-patient department to provide an analytical service similar to that provided for the determination of prothrombin time at the anticoagulant clinic.


Assuntos
Carbamazepina/análogos & derivados , Carbamazepina/sangue , Fenobarbital/sangue , Fenitoína/sangue , Cromatografia Líquida de Alta Pressão/métodos , Estudos de Avaliação como Assunto , Humanos
17.
Ann Clin Biochem ; 24 ( Pt 1): 80-4, 1987 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-3827190

RESUMO

Ethylene glycol in plasma, urine or dialysis fluid is analysed as the phenylboronate derivative by mixing with acetonitrile/acidified 2,2-dimethoxypropane containing phenylboronic acid. After centrifugation, a portion of the supernatant is analysed directly by gas-liquid chromatography using a 3% OV-101 column at 150 degrees C and flame-ionisation detection. Propane-1,3-diol is used as a reactive internal standard. The limit of accurate measurement is at least 0.1 g/L and the linear range extends up to 5.0 g/L. No sources of interference have been identified.


Assuntos
Etilenoglicóis/análise , Adulto , Cromatografia Gasosa , Etanol/sangue , Etilenoglicol , Etilenoglicóis/sangue , Etilenoglicóis/urina , Humanos , Masculino , Metanol/sangue , Métodos
18.
Ann Clin Biochem ; 25 ( Pt 1): 96-101, 1988 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-3355092

RESUMO

Experience in clinical chemistry of direct reading ion-selective electrode analysers for the measurement of plasma Na+ and K+ concentrations has shown that the results obtained on any specimen may vary significantly from one make of instrument to another. To overcome these differences, the European Working Group on ISEs of the IFCC Expert Panel on pH, Blood Gases and Electrolytes have proposed that instruments should be standardised to report Na+ and K+ concentrations in undiluted plasma to agree with flame emission spectrometry in samples with normal plasma water bicarbonate concentrations and normal pH. In designing and setting the calibration of a new ISE analyser for Na+ and K+, the Corning 614, the manufacturer has attempted to satisfy this proposal using a large number of specimens obtained from patients. This paper presents details of the procedure used and the results of an independent evaluation of its validity in routine clinical practice.


Assuntos
Potássio/sangue , Sódio/sangue , Eletrodos , Estudos de Avaliação como Assunto , Humanos , Espectrofotometria Atômica
19.
Ann Clin Biochem ; 28 ( Pt 1): 68-72, 1991 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-2024938

RESUMO

There is controversy about whether protein interferes with ion measurements using ion-selective electrodes. We have investigated the effects of changes in the salt-bridge composition of five commercially available analysers with open, membrane-restricted or porous frit-restricted reference electrode junctions on measurements of an albumin solution prepared by gel filtration. When the manufacturers' salt bridges were used, instruments with open or membrane-restricted junctions showed apparent increases in the activity of ionized calcium, sodium and potassium in the presence of protein. When the hypertonic bridge solutions were replaced with 150 mmol/L potassium chloride this increase disappeared. The instrument with a porous frit-restricted junction showed no protein effect, but its response to changes in sample sodium chloride concentration in protein-free solution suggested that its junction was functionally equivalent to that formed with an isotonic sodium chloride bridge. Our results emphasize that liquid junction design and composition affect ion measurements in protein-containing solutions and suggest that the use of hypertonic bridge solutions for biological samples needs to be re-examined.


Assuntos
Eletrodos , Cloreto de Cálcio/metabolismo , Cromatografia em Gel , Desenho de Equipamento , Cloreto de Potássio/metabolismo , Solução Salina Hipertônica , Soroalbumina Bovina/metabolismo , Cloreto de Sódio/metabolismo
20.
Ann Clin Biochem ; 24 ( Pt 1): 36-40, 1987 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-3827182

RESUMO

Investigation of the uptake and metabolism of drugs by organs such as the liver may allow assessment of specific aspects of organ function. Rifampicin, when orally administered, is transported into the hepatocyte from portal blood and thence passes, with its deacetylated metabolite, into the systemic circulation and into bile. This paper reports an investigation of the pharmacokinetics of a sub-therapeutic oral dose of rifampicin in healthy subjects, in patients with cirrhosis and in subjects with Gilbert's syndrome. The areas under the plasma concentration curves (AUC) in patients with cirrhosis were significantly greater than in healthy subjects. Subjects with Gilbert's syndrome had decreased AUCs compared with healthy subjects and were clearly distinguished from patients with cirrhosis. Rifampicin concentration in serum was measured by HPLC using a novel direct injection technique.


Assuntos
Fígado/fisiologia , Rifampina , Acetilação , Administração Oral , Adulto , Bile/metabolismo , Transporte Biológico Ativo , Cromatografia Líquida de Alta Pressão , Feminino , Doença de Gilbert/fisiopatologia , Meia-Vida , Humanos , Cinética , Cirrose Hepática/fisiopatologia , Masculino , Rifampina/administração & dosagem
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