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1.
Nicotine Tob Res ; 24(12): 1959-1967, 2022 11 12.
Artigo em Inglês | MEDLINE | ID: mdl-35704338

RESUMO

INTRODUCTION: Regulators are considering reducing the nicotine content in cigarettes to a minimally addictive level. This could particularly benefit smokers from populations vulnerable to heavy smoking and difficulties quitting. We assessed predictors of adherence among adults from vulnerable populations assigned to use very low nicotine content cigarettes (VLNCs) in randomized clinical trials, to identify characteristics of those who require additional assistance if a nicotine reduction policy were implemented. AIMS AND METHODS: Data came from three populations of vulnerable adult smokers assigned to use VLNC cigarettes (0.4 mg/g nicotine) during 12-week randomized controlled trials (n = 286): Socioeconomically disadvantaged women of reproductive age, opioid-maintained adults, and adults with affective disorders. Logistic and linear regressions modeled predictors of adherence based on changes in cotinine at week-6 and week-12 assessments relative to baseline, and as a 90% reduction in cotinine relative to baseline (full adherence: yes/no). Predictors included satisfaction with study cigarettes, craving, nicotine dependence severity, withdrawal, population membership, baseline affective-disorder symptoms, and sociodemographic characteristics. RESULTS: Dependence severity was negatively associated with both adherence measures at week 6 (p < .01), whereas increased satisfaction with study cigarettes and age were positively associated with both measures at weeks 6 and 12 (p < .01). Opioid-maintained adults exhibited reduced adherence and were less likely to reach full adherence at week 12 compared to disadvantaged women (p = .02). CONCLUSIONS: Factors associated with VLNC adherence in vulnerable populations are similar to those in the general population of smokers. Furthermore, studies are indicated investigating nicotine supplements (e.g., e-cigarettes, NRT) to support highly dependent adults faced with using VLNCs. IMPLICATIONS: This study identified factors predicting difficulty maintaining adherence to a regimen of very low nicotine content cigarettes (VLNC) among adults from vulnerable populations. Findings suggested that factors predicting difficulty maintaining adherence (greater nicotine dependence and low satisfaction with study-provided VLNC) were common across vulnerable smokers and the general population of adults who smoke. Furthermore, research should investigate alternatives to support highly dependent adults, such as pairing VLNC with supplemental, noncombusted nicotine. Some vulnerable populations (e.g., opioid-maintained adults) may be especially in need of supplemental, noncombusted nicotine.


Assuntos
Sistemas Eletrônicos de Liberação de Nicotina , Abandono do Hábito de Fumar , Produtos do Tabaco , Tabagismo , Adulto , Humanos , Feminino , Nicotina , Cotinina , Abandono do Hábito de Fumar/psicologia , Populações Vulneráveis , Analgésicos Opioides , Fumar
2.
BMC Cancer ; 20(1): 940, 2020 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-32998716

RESUMO

BACKGROUND: After High-Dose Methotrexate (HD-MTX), folinic acid rescue therapy (Leucovorin) is administered to reduce side effects in pediatric acute lymphoblastic leukemia (ALL) patients. Leucovorin and MTX are structural analogues, possibly competing for cellular transport and intracellular metabolism. We hypothesize that Leucovorin accumulates during consecutive courses, which might result in a lower MTX uptake. METHODS: We prospectively measured red blood cell (RBC) folate and MTX levels during four HD-MTX and Leucovorin courses in 43 patients treated according the DCOG ALL-11 protocol with 2-weekly HD-MTX (5 g/m2/dose) and Leucovorin (15 mg/m2/dose) using LC-MS/MS. We estimated a linear mixed model to assess the relationship between these variables over time. RESULTS: Both RBC MTX-PG and folate levels increased significantly during protocol M. MTX-PG2-5 levels increased most substantially after the first two HD-MTX courses (until median 113.0 nmol/L, IQR 76.8-165.2) after which levels plateaued during the 3d and 4th course (until median 141.3 nmol/L, IQR 100.2-190.2). In parallel, folate levels increased most substantially after the first two HD-MTX courses (until median 401.6 nmol/L, IQR 163.3-594.2) after which levels plateaued during the 3d and 4th course (until median 411.5 nmol/L, IQR 240.3-665.6). The ratio folate/MTX-PG decreased significantly over time, which was mostly due to the relatively higher increase (delta) of MTX-PG. CONCLUSION: These results suggest that the increase in RBC folate levels does not seem to have a large effect on RBC MTX levels. Future studies, assessing competition of Leucovorin and MTX on other cellular mechanisms which might negatively affect treatment efficacy, are necessary.


Assuntos
Ácido Fólico/sangue , Metotrexato/sangue , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Adolescente , Antimetabólitos Antineoplásicos/administração & dosagem , Antimetabólitos Antineoplásicos/sangue , Criança , Pré-Escolar , Cromatografia Líquida , Eritrócitos/efeitos dos fármacos , Feminino , Humanos , Lactente , Leucovorina/administração & dosagem , Leucovorina/sangue , Masculino , Metotrexato/administração & dosagem , Leucemia-Linfoma Linfoblástico de Células Precursoras/sangue , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologia , Espectrometria de Massas em Tandem , Resultado do Tratamento
3.
Support Care Cancer ; 27(1): 183-190, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29922939

RESUMO

PURPOSE: Children with acute lymphoblastic leukemia (ALL) are at increased risk of vitamin D deficiency, which might make them more susceptible to developing adverse events. Previous studies showed that low vitamin D levels were associated with an increased inflammatory mucosal state and impaired mucosal tissue barriers. We examined the prevalence of vitamin D deficiency and studied the association between vitamin D levels and methotrexate (MTX)-induced oral mucositis in pediatric ALL. METHODS: We assessed 25-hydroxyvitamin D (25(OH)D3) and 24,25-dihydroxyvitamin D (24,25(OH)2D3) levels in 99 children with ALL before the start of 4 × 5 g/m2 high-dose methotrexate (HD-MTX) (T0) and in 81/99 children after discontinuation of HD-MTX (T1). Two cutoff values for vitamin D deficiency exist: 25(OH)D3 levels < 30 and < 50 nmol/L. Oral mucositis was defined as grade ≥ 3 according to the National Cancer Institute Criteria. RESULTS: Vitamin D deficiency occurred in respectively 8% (< 30 nmol/L) and 33% (< 50 nmol/L) of the patients at T0, and more frequently in children > 4 years of age as compared to children between 1 and 4 years of age. A decrease in 25(OH)D3 levels during HD-MTX therapy was associated with developing severe oral mucositis (OR 1.6; 95% CI [1.1-2.4]). 25(OH)D3 and 24,25(OH)2D3 levels at T0 and the change in 24,25(OH)2D3 levels during therapy were not associated with the development of severe oral mucositis. CONCLUSIONS: This study showed that vitamin D deficiency occurs frequently in pediatric ALL patients above the age of 4 years. A decrease in 25(OH)D3 levels during MTX therapy was observed in children with ALL that developed severe oral mucositis.


Assuntos
Metotrexato/efeitos adversos , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Leucemia-Linfoma Linfoblástico de Células Precursoras/epidemiologia , Estomatite/induzido quimicamente , Estomatite/epidemiologia , Deficiência de Vitamina D/epidemiologia , Vitamina D/sangue , Adolescente , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Criança , Pré-Escolar , Estudos de Coortes , Relação Dose-Resposta a Droga , Feminino , Humanos , Lactente , Masculino , Metotrexato/administração & dosagem , Países Baixos/epidemiologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/sangue , Leucemia-Linfoma Linfoblástico de Células Precursoras/complicações , Prevalência , Estomatite/sangue , Estomatite/complicações , Deficiência de Vitamina D/sangue , Deficiência de Vitamina D/complicações , Suspensão de Tratamento , Adulto Jovem
4.
Phys Rev Lett ; 121(1): 012501, 2018 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-30028163

RESUMO

Lifetime measurements of excited states in the neutron-rich nucleus ^{43}S were performed by applying the recoil-distance method on fast rare-isotope beams in conjunction with the Gamma-Ray Energy Tracking In-beam Nuclear Array. The new data based on γγ coincidences and lifetime measurements resolve a doublet of (3/2^{-}) and (5/2^{-}) states at low excitation energies. Results were compared to the π(sd)-ν(pf) shell model and antisymmetrized molecular dynamics calculations. The consistency with the theoretical calculations identifies a possible appearance of three coexisting bands near the ground state of ^{43}S: the K^{π}=1/2^{-} band built on a prolate-deformed ground state, a band built on an isomer with a 1f_{7/2}^{-1} character, and a suggested excited band built on a newly discovered doublet state. The latter further confirms the collapse of the N=28 shell closure in the neutron-rich region.

5.
Phys Rev Lett ; 121(26): 262501, 2018 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-30636164

RESUMO

An enhanced low-energy electric dipole (E1) strength is identified for the weakly bound excited states of the neutron-rich isotope ^{27}Ne. The Doppler-shift lifetime measurements employing a combination of the γ-ray tracking array GRETINA, the plunger device, and the S800 spectrograph determine the lower limit of 0.030 e^{2} fm^{2} or 0.052 W.u. for the 1/2^{+}→3/2^{-} E1 transition in ^{27}Ne, representing one of the strongest E1 strengths observed among the bound discrete states in this mass region. This value is at least 30 times larger than that measured for the 3/2^{-} decay to the 3/2_{gs}^{+} ground state. A comparison of the present results to large-scale shell-model calculations points to an important role of core excitations and deformation in the observed E1 enhancement, suggesting a novel example of the electric dipole modes manifested in weakly bound deformed systems.

6.
Anal Bioanal Chem ; 405(5): 1673-81, 2013 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-23239179

RESUMO

The folate antagonist methotrexate (MTX) is the anchor drug in the treatment of rheumatoid arthritis. The therapeutic effects of MTX are attributed to the intracellular levels of MTX, present in the cell as polyglutamates (MTXPGn). We developed a new liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS)-based assay to separately quantitate MTXPGn in red blood cells using stable-isotope-labelled internal standards. Samples were analyzed by LC-ESI-MS/MS using a Waters Acquity UPLC BEH C18 column with a 5-100% organic gradient of 10 mM ammonium bicarbonate (pH 10) and methanol. The analysis consisted of simple sample preparation and a 6-min run time. Detection was done using a Waters Acquity UPLC coupled to a Waters Quattro Premier XE with electrospray ionization operating in the positive ionization mode. Assay validation was performed following recent Food and Drug Administration guidelines. The method was linear from 1-1,000 nM for all MTXPGn (R(2) > 0.99). The coefficient of variation ranged from 1-4% for intraday precision and 6-15% for interday precision. Samples were stable for at least 1 month at -80 °C. Recovery ranged from 98-100%, and the relative matrix-effect varied from 95-99%. The lower limit of quantitation was 1 nM for each MTXPGn. Fifty patient samples from the tREACH study were analyzed. The MTXPGn concentration and distribution of these samples were comparable with values reported in literature. The developed LC-ESI-MS/MS method for the quantitative measurement of MTXPGn in red blood cells is both sensitive and precise within the clinically relevant range. The method can be easily applied in clinical laboratories due to the combination of simple pre-treatment with robust LC-ESI-MS/MS.


Assuntos
Antirreumáticos/sangue , Artrite Reumatoide/tratamento farmacológico , Monitoramento de Medicamentos/métodos , Eritrócitos/química , Metotrexato/sangue , Ácido Poliglutâmico/sangue , Espectrometria de Massas por Ionização por Electrospray/métodos , Antirreumáticos/análise , Artrite Reumatoide/sangue , Cromatografia Líquida de Alta Pressão/métodos , Humanos , Limite de Detecção , Metotrexato/análise , Ácido Poliglutâmico/análise , Sensibilidade e Especificidade , Espectrometria de Massas em Tandem/métodos
7.
Eur Addict Res ; 16(2): 99-107, 2010.
Artigo em Inglês | MEDLINE | ID: mdl-20160444

RESUMO

BACKGROUND: Little comparable information is available regarding clinical characteristics of opioid-dependent women from different countries. In the present study, women from the USA, Canada and a Central European country, Austria, screened for participation in the Maternal Opioid Treatment Human Experimental Research study, were compared with respect to their demographic and addiction histories. METHODS: Pregnant women (n = 1,074) were screened for study participation using uniformed clinical criteria and instruments. The screening results were compared with regard to exclusion, demographics, drug use, and psychosocial and treatment histories. RESULTS: Compared to the screened US and Canadian women, Austrian women were more likely to be younger (p < 0.001), white (p < 0.001), had significantly lower levels of educational attainment (p < 0.001), were less likely to use opioids daily (p < 0.001) and more likely to have been prescribed buprenorphine (p < 0.001). Compared to both rural and urban US groups, the Austrian group was less likely to have legal issues (p < 0.001) and was younger when first prescribed agonist medication (p < 0.001). CONCLUSION: The differences between North American and European groups may offer unique insights concerning treatment and pregnancy outcomes for opioid-dependent pregnant women.


Assuntos
Usuários de Drogas/estatística & dados numéricos , Programas de Rastreamento/métodos , Transtornos Relacionados ao Uso de Opioides/tratamento farmacológico , Seleção de Pacientes , Complicações na Gravidez/tratamento farmacológico , Adolescente , Adulto , Distribuição por Idade , Áustria , Canadá , Usuários de Drogas/psicologia , Escolaridade , Definição da Elegibilidade , Feminino , Humanos , Antagonistas de Entorpecentes/uso terapêutico , Transtornos Relacionados ao Uso de Opioides/psicologia , Gravidez , Complicações na Gravidez/psicologia , População Rural , Fatores Socioeconômicos , Estados Unidos , População Urbana , Adulto Jovem
9.
PLoS One ; 15(5): e0231588, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32421698

RESUMO

We have recently established a protocol to grow wildtype human oral mucosa organoids. These three-dimensional structures can be maintained in culture long-term, do not require immortalization, and recapitulate the multilayered composition of the epithelial lining of the oral mucosa. Here, we validate the use of this model to study the effect of Leucovorin (LV) on Methotrexate (MTX)-induced toxicity. MTX is a chemotherapeutic agent used in the treatment of pediatric acute lymphoblastic leukemia. Although effective, the use of MTX often results in severe side-effects, including oral mucositis, which is characterized by epithelial cell death. Here, we show that organoids are sensitive to MTX, and that the addition of LV reduces MTX toxicity, in both a concentration- and timing-dependent manner. Additionally, we show that a 24 hour 'pretreatment' with LV reduces MTX-induced cell death, suggesting that such a pretreatment could decrease mucositis in patients. Taken together, we provide the first in vitro model to study the effect of MTX on wildtype oral mucosa cells. Our findings underscore the relevance of the clinically applied LV regimen and highlight the potential of this model to further optimize modifications in dosing and timing of Leucovorin on oral mucosa cells.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/efeitos adversos , Apoptose/efeitos dos fármacos , Mucosa Bucal/efeitos dos fármacos , Organoides/patologia , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Estomatite/patologia , Adolescente , Criança , Humanos , Técnicas In Vitro , Leucovorina/administração & dosagem , Metotrexato/administração & dosagem , Mucosa Bucal/patologia , Técnicas de Cultura de Órgãos , Organoides/efeitos dos fármacos , Leucemia-Linfoma Linfoblástico de Células Precursoras/patologia , Estomatite/induzido quimicamente
10.
Am J Drug Alcohol Abuse ; 35(5): 375-80, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-20180667

RESUMO

BACKGROUND: Little is known about the prevalence and severity of smoking in pregnant opioid dependent patients. OBJECTIVES: To first characterize the prevalence and severity of smoking in pregnant patients screened for a randomized controlled trial, Maternal Opioid Treatment: Human Experimental Research (MOTHER), comparing two agonist medications; and second, to compare the MOTHER screening sample to published samples of other pregnant and/or patients with substances use disorders. METHODS: Pregnant women (N = 108) screened for entry into an agonist medication comparison study were retrospectively compared on smoking variables to samples of pregnant methadone-maintained patients (N = 50), pregnant opioid or cocaine dependent patients (N = 240), non-pregnant methadone-maintained women (N = 75), and pregnant non-drug-addicted patients (N = 1,516). RESULTS: Of screened patients, 88% (n = 95) smoked for a mean of 140 months (SD = 79.0) starting at a mean age of 14 (SD = 3.5). This rate was similar to substance use disordered patients and significantly higher compared to general pregnant patients (88% vs. 22%, p < .001). CONCLUSION AND SCIENTIFIC SIGNIFICANCE: Aggressive efforts are needed to reduce/eliminate smoking in substance-abusing pregnant women.


Assuntos
Transtornos Relacionados ao Uso de Cocaína/tratamento farmacológico , Metadona/uso terapêutico , Transtornos Relacionados ao Uso de Opioides/tratamento farmacológico , Fumar/epidemiologia , Adulto , Feminino , Comportamentos Relacionados com a Saúde , Humanos , Entorpecentes/uso terapêutico , Gravidez , Prevalência , Índice de Gravidade de Doença , Inquéritos e Questionários
11.
Anaesthesist ; 58(11): 1119-22, 2009 Nov.
Artigo em Alemão | MEDLINE | ID: mdl-19795099

RESUMO

Heparin-induced thrombocytopenia (HIT) type II is a life-threatening complication of heparin therapy. The present case report describes the therapeutic management of HIT type II with thrombosis using the direct thrombin inhibitor argatroban in an intensive care patient after successful surgery of a ruptured infrarenal abdominal aortic aneurysm. Despite high dosing and long-term application of argatroban, anticoagulation remained uncritical and was well controllable by monitoring the activated partial thromboplastin time. In consideration of the pharmacological characteristics, therapy suspension due to invasive interventions and switching to an oral vitamin K antagonist by defined algorithm resulted in an effective management.


Assuntos
Anticoagulantes/efeitos adversos , Anticoagulantes/uso terapêutico , Heparina/efeitos adversos , Ácidos Pipecólicos/uso terapêutico , Trombina/antagonistas & inibidores , Trombocitopenia/induzido quimicamente , Trombocitopenia/tratamento farmacológico , Trombose/complicações , Idoso , Aneurisma da Aorta Abdominal/cirurgia , Ruptura Aórtica/cirurgia , Arginina/análogos & derivados , Exantema/complicações , Exantema/tratamento farmacológico , Humanos , Masculino , Tempo de Tromboplastina Parcial , Contagem de Plaquetas , Sulfonamidas , Trombocitopenia/complicações , Trombose/sangue
12.
Crit Rev Oncol Hematol ; 142: 1-8, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31323533

RESUMO

INTRODUCTION: This study aimed to determine the efficacy of different Leucovorin regimens to reduce oral mucositis in children with acute lymphoblastic leukemia after high-dose Methotrexate (HD-MTX). METHODS: Twelve articles were included in a systematic literature review. Articles were categorized into low/medium/high risk of bias. RESULTS: As no randomized controlled trial assessing the effect of Leucovorin has been performed, the efficacy of Leucovorin to reduce oral mucositis remains unknown. Leucovorin was initiated at 24, 36 or 42 h after HD-MTX at a dose of 15 or 30 mg/m2. No meta-analysis could be performed as treatment regimens differed. When comparing studies with similar HD-MTX doses, we observed lower oral mucositis rates in regimens with higher cumulative doses of Leucovorin and early initiation of Leucovorin after MTX. CONCLUSION: Even though future studies are necessary, higher cumulative Leucovorin doses and early initiation of Leucovorin after start of MTX seem to reduce oral mucositis.


Assuntos
Leucovorina/uso terapêutico , Metotrexato/efeitos adversos , Leucemia-Linfoma Linfoblástico de Células Precursoras/tratamento farmacológico , Estomatite/tratamento farmacológico , Adolescente , Antineoplásicos/efeitos adversos , Antineoplásicos/uso terapêutico , Criança , Pré-Escolar , Humanos , Lactente , Leucovorina/administração & dosagem , Metotrexato/uso terapêutico , Estomatite/induzido quimicamente , Estomatite/prevenção & controle , Resultado do Tratamento , Adulto Jovem
13.
Eur J Radiol ; 85(12): 2275-2280, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27842677

RESUMO

BACKGROUND AND PURPOSE: Primary MRI diagnosis of spinal intramedullary tumor-suspected lesions can be challenging and often requires spinal biopsy or resection with a substantial risk of neurological deficits. We evaluated whether Diffusion Tensor Imaging (DTI) tractography can facilitate the differential diagnosis. MATERIALS AND METHODS: Twenty-five consecutive patients with an intramedullary tumor-suspected lesion considered for spinal surgery were studied with a Diffusion-weighted multi-shot read out segmented EPI sequence (RESOLVE). White matter tracts ("streamlines") were calculated using the FACT algorithm and visually co-registered to a T2-weighted 3D sequence. The fused images were assessed concerning spinal streamline appearance as normal, displaced or terminated. Definite diagnosis was verified by histological analysis or further clinical work-up. RESULTS: All patients with normal appearing streamlines (n=6) showed an acute inflammatory demyelinating pathology in the further clinical work-up. In 10 patients streamline displacing lesions were found from which 5 patients underwent a surgical treatment with histologically confirmed low-grade tumors like ependymomas and pilocytic astrocytomas. In nine patients streamlines were terminated, from which 6 patients received a histology proven diagnoses with a more heterogenous spectrum (3 cases of high grade tumor, 1 case of low grade tumor with intralesional hemorrhage and 2 cases with gliosis but no tumor cells). CONCLUSION: Using multi-shot DTI spinal tractography acute inflammatory lesions can be differentiated from other tumorous intramedullary lesions. The entity diagnosis of spinal tumors seems to be more challenging, primarily due to the variety of factors like invasivity, expansion or intralesional hemorrhage.


Assuntos
Imagem de Tensor de Difusão/métodos , Neoplasias da Medula Espinal/diagnóstico por imagem , Adolescente , Adulto , Idoso , Algoritmos , Astrocitoma/diagnóstico por imagem , Astrocitoma/patologia , Criança , Pré-Escolar , Diagnóstico Diferencial , Ependimoma/diagnóstico por imagem , Ependimoma/patologia , Feminino , Gliose/diagnóstico por imagem , Gliose/patologia , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Masculino , Pessoa de Meia-Idade , Mielite/diagnóstico por imagem , Mielite/patologia , Procedimentos Neurocirúrgicos , Estudos Prospectivos , Razão Sinal-Ruído , Medula Espinal/diagnóstico por imagem , Medula Espinal/patologia , Neoplasias da Medula Espinal/patologia , Adulto Jovem
14.
Eur J Hum Genet ; 7(3): 393-6, 1999 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-10234517

RESUMO

Neural tube defects (NTDs) are the most common congenital malformations and are considered to have a multifactorial origin, having both genetic and environmental components. Periconceptional folate administration reduces the recurrence and occurrence risk by 70-100%. Recently we discovered the first genetic risk factors for NTDs: the 677 C-->T and the 1298 A-->C mutations in the methylenetetrahydrofolate reductase gene explaining at the most 35-50% of the protective effect of folate. In this study we further explored the genetic component of NTDs by analysing the coding region, including the intron-exon boundaries and signal sequences of the folate receptor genes by SSCP analysis. Among 39 patients with spina bifida (SB), 47 mothers with a child with SB, and 10 controls, no polymorphism was present in the folate receptor alpha (FR-alpha) gene or in the folate receptor beta (FR-beta) gene.


Assuntos
Proteínas de Transporte/genética , Defeitos do Tubo Neural/genética , Receptores de Superfície Celular , Adulto , Feminino , Receptores de Folato com Âncoras de GPI , Humanos , Polimorfismo Conformacional de Fita Simples
15.
Eur J Hum Genet ; 9(8): 583-9, 2001 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-11528503

RESUMO

Molecular defects in genes encoding enzymes involved in homocysteine metabolism may account for mild hyperhomocysteinaemia, an independent and graded risk factor for cardiovascular disease (CVD). Although heterozygosity for cystathionine beta-synthase (CBS) deficiency has been excluded as a major genetic cause of mild hyperhomocysteinaemia in vascular disease, mutations in (non-)coding DNA sequences may lead to a mildly decreased CBS expression and, consequently, to elevated plasma homocysteine levels. We assessed the association between a 31 bp VNTR, that spans the exon 13-intron 13 boundary of the CBS gene, and fasting, post-methionine load and increase upon methionine load plasma homocysteine levels in 190 patients with arterial occlusive disease, and in 381 controls. The 31 bp VNTR consists of 16, 17, 18, 19 or 21 repeat units and shows a significant increase in plasma homocysteine concentrations with an increasing number of repeat elements, in particular after methionine loading. In 26 vascular disease patients the relationship between this 31 bp VNTR and CBS enzyme activity in cultured fibroblasts was studied. The CBS enzyme activity decreased with increasing number of repeat units of the 31 bp VNTR. RT-PCR experiments showed evidence of alternative splicing at the exon 13-intron 13 splice junction site. The 31 bp VNTR in the CBS gene is associated with post-methionine load hyperhomocysteinaemia that may predispose individuals to an increased risk of cardiovascular diseases.


Assuntos
Cistationina beta-Sintase/genética , Cistationina beta-Sintase/metabolismo , Homocisteína/sangue , Homocisteína/genética , Repetições Minissatélites/genética , Alelos , Processamento Alternativo/genética , Arteriopatias Oclusivas/sangue , Arteriopatias Oclusivas/enzimologia , Arteriopatias Oclusivas/genética , Sequência Consenso/genética , Ativação Enzimática/genética , Éxons/genética , Feminino , Frequência do Gene/genética , Genótipo , Humanos , Íntrons/genética , Masculino , Pessoa de Meia-Idade , Polimorfismo Genético/genética , Fatores de Risco
16.
FEBS Lett ; 431(2): 175-9, 1998 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-9708897

RESUMO

We elucidated the intron-exon boundaries of the 15 coding exons of the human cystathionine beta-synthase (CBS) gene in order to establish an improved method based on PCR and direct sequencing for detection of CBS mutations. Using this method we identified the pathogenic mutations in two Danish siblings with CBS deficiency. Patients were compound heterozygotes: we detected the 833T-->C mutation and a novel 22 bp deletion of exon 4 (493-514del) that introduces a frameshift and a stop codon immediately after the deletion. The deletion resulted in no detectable mRNA from this allele, as assessed by sequencing of cDNA. The established method represents an improvement of the existing method based on sequencing of cDNA because it permits the detection of mutations within the entire coding region of the CBS gene from a peripheral blood sample, including splice mutations and mutations resulting in the lack or a reduced amount of transcript.


Assuntos
Cistationina beta-Sintase/genética , Deleção de Genes , Adulto , Sequência de Bases , Cistationina beta-Sintase/deficiência , Cistationina beta-Sintase/metabolismo , Análise Mutacional de DNA , Primers do DNA , Éxons , Feminino , Fibroblastos/enzimologia , Testes Genéticos/métodos , Homocistinúria/enzimologia , Homocistinúria/genética , Humanos , Íntrons , Masculino , Dados de Sequência Molecular , Linhagem , Reação em Cadeia da Polimerase
17.
J Thromb Haemost ; 2(5): 750-3, 2004 May.
Artigo em Inglês | MEDLINE | ID: mdl-15099281

RESUMO

BACKGROUND: Venous thrombosis is a multicausal disease involving both genetic as well as acquired risk factors. Hyperhomocysteinemia is associated with a 2-fold increased risk of recurrent venous thrombosis (RVT). Recently, the 894 G > T variant of endothelial nitric oxide synthase (eNOS) was postulated to be associated with hyperhomocysteinemia. OBJECTIVES: We hypothesized an interrelation of hyperhomocysteinemia, the eNOS 894 G > T variant and RVT risk. METHODS: The eNOS 894 G > T variant was studied in 170 cases with a history of RVT and 433 controls from the general population. RESULTS: The eNOS 894 TT genotype may increase RVT risk [odds ratio (OR) 1.3 (0.7-2.6)], but no association of the eNOS 894 G > T variant with elevated homocysteine was found in controls. Interestingly, in RVT cases the coexistence of both the 894 TT genotype and elevated tHcy levels (> 90th percentile) was more frequently present than in controls, which led to a substantially increased risk of recurrent venous thrombosis [fasting tHcy OR 5.3 (1.1-24.1), postload tHcy OR 6.5 (1.6-29.5)]. CONCLUSION: The results of the present study demonstrate that the eNOS 894 G > T variation interacts with elevated tHcy levels, leading to an increased risk of recurrent thrombotic events. This interaction points in the direction of S-nitrosation as a mechanism by which homocysteine exerts its detrimental effects on the hemostatic system.


Assuntos
Hiper-Homocisteinemia/complicações , Óxido Nítrico Sintase/genética , Polimorfismo de Nucleotídeo Único , Trombose Venosa/genética , Estudos de Casos e Controles , Genótipo , Homocisteína/metabolismo , Humanos , Hiper-Homocisteinemia/epidemiologia , Epidemiologia Molecular , Óxido Nítrico Sintase Tipo III , Nitrosação , Razão de Chances , Recidiva , Risco , Trombose Venosa/epidemiologia , Trombose Venosa/etiologia
18.
Thromb Haemost ; 79(2): 254-8, 1998 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9493571

RESUMO

Mild hyperhomocysteinemia is an established risk factor for both arteriosclerosis and thrombosis, and may be caused by genetic and environmental factors. Methylenetetrahydrofolate reductase (MTHFR) catalyzes the reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, the cofactor for the methylation of homocysteine to methionine. Individuals with the thermolabile variant of MTHFR have decreased MTHFR activities, resulting in elevated plasma homocysteine concentrations. A homozygous 677C-->T transition in the MTHFR gene has recently been identified as the cause of reduced enzyme activity and thermolability of the protein. We studied the frequency of the homozygous mutant (+/+) genotype in 471 patients with deep-vein thrombosis and 474 healthy controls enrolled in The Leiden Thrombophilia Study (LETS), its interaction with factor V Leiden, and assessed the association between the MTHFR genotypes and plasma homocysteine concentration. Homozygosity for the 677C-->T polymorphism was observed in 47 (10%) patients, and in 47 (9.9%) controls (OR 1.01 [95% CI: 0.7-1.5]). No modified risk of the (+/+) genotype was observed in carriers of factor V Leiden. Our data suggest that, although the homozygous mutant genotype is associated with elevated plasma homocysteine concentrations, this homozygous mutation itself is not a genetic risk factor for deep-vein thrombosis, irrespective of factor V Leiden genotype.


Assuntos
Fator V/genética , Mutação , Oxirredutases atuantes sobre Doadores de Grupo CH-NH/genética , Tromboflebite/genética , Adolescente , Adulto , Idoso , Homocisteína/sangue , Homozigoto , Humanos , Metilenotetra-Hidrofolato Redutase (NADPH2) , Pessoa de Meia-Idade , Fatores de Risco , Tromboflebite/sangue
19.
QJM ; 90(8): 511-7, 1997 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-9327029

RESUMO

Elevated homocysteine (Hcy) levels are observed in two apparently unrelated diseases: neural-tube defects (NTD) and premature vascular disease. Defective human methionine synthase (MS) could result in elevated Hcy levels. We sequenced the coding region of MS in 8 hyperhomocysteinaemic patients (4 NTD patients and 4 patients with pregnancies complicated by spiral arterial disease, SAD). We identified only one mutation resulting in an amino acid substitution: an A-->G transition at bp 2756, converting an aspartic acid (D919) into a glycine (G). We screened genomic DNA for the presence of this mutation in 56 NTD patients, 69 mothers of children with NTD, 108 SAD patients and 364 controls. There was no increased prevalence of the GG and AG genotypes in NTD patients, their mothers or SAD patients. The D919G mutation does not seem to be a risk factor for NTD or vascular disease. We then examined the mean Hcy levels for each MS genotype. There was no correlation between GG- or AG-genotype and Hcy levels. The D919G mutation is thus a fairly prevalent, and probably benign polymorphism. This study, though limited, provides no evidence for a major involvement of MS in the aetiology of homocysteine-related diseases such as NTD or vascular disease.


Assuntos
5-Metiltetra-Hidrofolato-Homocisteína S-Metiltransferase/genética , Arteriopatias Oclusivas/enzimologia , Defeitos do Tubo Neural/enzimologia , Complicações Cardiovasculares na Gravidez/enzimologia , Adolescente , Adulto , Arteriopatias Oclusivas/sangue , Feminino , Genótipo , Homocisteína/sangue , Humanos , Masculino , Dados de Sequência Molecular , Mutação , Defeitos do Tubo Neural/sangue , Razão de Chances , Reação em Cadeia da Polimerase , Gravidez , Complicações Cardiovasculares na Gravidez/sangue , Análise de Sequência de DNA
20.
J Magn Reson ; 135(1): 17-22, 1998 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-9799669

RESUMO

Electrical transport in porous media plays an important role in many fields of pure and applied science. The basic microscopic processes of the charge transport have attracted considerable theoretical interest for a long time. However, on a microscopic level there was up to now no experimental access to this problem. In the present paper we demonstrate, by using a suited porous system, that two combined NMR methods can offer such a first experimental access. We apply common PFG NMR methods and the special electrophoretic NMR (ENMR) technique for the measurement of self-diffusion coefficient D+ and electric mobility u+ of a cation ((C4H9)+4) in a disordered gel-like medium (Sephadex LH-20) filled with electrolyte solution. We find a, qualitatively expected, observation time-dependence of D+, but for the first time such a time-dependence is also observed for u+, which means the detection of the phenomenon of "anomalous field assisted diffusion" or "anomalous mobility." For the measurement of the short-time behavior of the mobility a new pulse sequence is presented. The time-dependent mobilities were measured at three different external electrical fields E. From the long-time behavior of D+, u+, and DH2O three independent values for the tortuosity T of the porous system could be derived. We find equality of the tortuosities T(D+) and T(u+), which represents a first experimental proof of the validity of the Einstein relation (D+ approximately u+) in a disordered medium. Finally, we discuss advantages of the possible use of "anomalous field assisted diffusion" over the commonly used "anomalous diffusion" in morphology studies by dynamic imaging in porous media.


Assuntos
Dextranos/química , Géis/química , Troca Iônica , Espectroscopia de Ressonância Magnética , Difusão , Condutividade Elétrica , Eletrólitos/química , Porosidade , Fatores de Tempo
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