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1.
JMA J ; 6(4): 499-504, 2023 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-37941695

RESUMO

Introduction: Remote antenatal checkups were conducted on the northernmost island of Japan to reduce the burden of hospital visits among pregnant women. This study aims to investigate the effectiveness and safety of remote antenatal checkups for pregnant women living on a remote island. Methods: This observational study included singleton pregnancies on Rebun Island between October 2020 and September 2022. General surgeons conducted medical interviews and performed fetal sonography using an obstetrician videoconference system at the main central hospital. The primary outcomes were the degrees of physical, mental, and economic burdens of hospital visits and the levels of anxiety and satisfaction with remote antenatal checkups as assessed using a questionnaire survey. Moreover, we investigated the incidence of adverse perinatal events, including maternal death, fetal death, neonatal death, severe neonatal neurological disorders, and other obstetric complications. Results: This study included 16 out of 22 pregnant women from Rebun Island who visited the central hospital. No adverse perinatal events occurred as a result of the remote antenatal checkups. One pregnant woman had gestational diabetes, whereas the others had no obstetric complications. The participants underwent a median of two remote antenatal checkups. According to a questionnaire survey, 90.0%, 80.0%, and 70.0% of the pregnant women perceived improvements in their physical, mental, and economic burdens, respectively. Although 70.0% of the participants experienced anxiety regarding remote antenatal checkups before the introduction, all were satisfied after delivery. Conclusions: Remote antenatal checkups effectively reduced the burden of hospital visits for pregnant women, who reported high levels of satisfaction. Furthermore, antenatal checkups were safely conducted on remote islands.

2.
Biosci Biotechnol Biochem ; 87(11): 1285-1294, 2023 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-37607777

RESUMO

Deletion of gene expression in the target tissues and cells is an effective strategy for elucidating the physiological functions of the protein of interest. For tissue-specific and/or inducible gene deletion, the Cre-loxP system has been widely used in various model organisms including medaka (Oryzias latipes). The epithelium is the key tissue, locating at the outermost area and playing a role in barrier to external stimuli. Despite a large genetic toolbox developed in medaka, there is no available Cre-driver line that works in an epithelium-specific manner. Here, we established epithelium-specific Cre-driver lines in medaka using a homology-directed repair mediated knock-in approach with CRISPR/Cas9, targeting each of periplakin and keratin genes. We show that Cre-recombinase is expressed exclusively in the epithelium in the knock-in lines and that it efficiently and specifically induces recombination in the tissues. These Cre-driver lines are useful for studying the functions of proteins expressed in the epithelium.


Assuntos
Oryzias , Animais , Oryzias/genética , Animais Geneticamente Modificados , Integrases/genética , Integrases/metabolismo
3.
J Obstet Gynaecol Res ; 49(10): 2544-2548, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37424208

RESUMO

The abdominal wall is a rare site of ectopic implantation. Laparoscopic surgery for early abdominal pregnancy, in contrast to its use for tubal ectopic pregnancy, remains controversial because of concerns regarding heavy bleeding at the implantation site. Treatment of early abdominal pregnancy must be individualized for each implantation site. Herein, we present a case of an early abdominal pregnancy implanted in the anterior abdominal wall that was successfully treated with laparoscopic surgery. A 28-year-old multiparous woman with a 6-week amenorrhea presented with acute abdominal pain. An ectopic pregnancy was suspected because of elevated serum human chorionic gonadotropin levels without a visible gestational sac on transvaginal ultrasonography. Diagnostic laparoscopy revealed a gestational sac hanging from the anterior abdominal wall near the previous cesarean section wound. Laparoscopic surgery was successfully performed, and the patient was discharged on postoperative day three. In the present case, laparoscopic surgery was beneficial.


Assuntos
Parede Abdominal , Laparoscopia , Gravidez Abdominal , Gravidez Tubária , Gravidez , Humanos , Feminino , Adulto , Gravidez Abdominal/diagnóstico , Gravidez Abdominal/cirurgia , Cesárea , Parede Abdominal/cirurgia , Gravidez Tubária/cirurgia
4.
Nutr Metab Cardiovasc Dis ; 32(8): 1841-1850, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35637084

RESUMO

BACKGROUND AND AIMS: Heart failure (HF) patients are at risk of developing type 2 diabetes. This study examined the association between adherence to the Dietary Approaches to Stop Hypertension (DASH) diet and insulin resistance among U.S. adults with HF. METHODS AND RESULTS: Using data from National Health and Nutrition Examination Survey 1999-2016 cycles, we included 348 individuals aged 20+ years with HF and no history of diabetes. DASH diet adherence index quartile 1 indicated the lowest and quartile 4 indicated the highest adherence. The highest level of insulin resistance was defined by the upper tertile of the Homeostatic Model Assessment of Insulin Resistance (HOMA-IR). Associations between level of insulin resistance and DASH diet adherence and its linear trends were examined using logistic regressions. Trend analyses showed that participants in upper DASH diet adherence index quartiles were more likely older, female, non-Hispanic White, of normal weight, and had lower levels of fasting insulin than those in lower quartiles. Median values of HOMA-IR from lowest to highest DASH diet adherence index quartiles were 3.1 (interquartile range, 1.8-5.5), 2.9 (1.7-5.6), 2.1 (1.1-3.7), and 2.1 (1.3-3.5). Multivariable logistic analyses indicated that participants with the highest compared to the lowest DASH adherence showed 77.1% lower odds of having the highest level of insulin resistance (0.229, 95% confidence interval: 0.073-0.716; p = 0.017 for linear trend). CONCLUSION: Good adherence to the DASH diet was associated with lower insulin resistance among community-dwelling HF patients. Heart healthy dietary patterns likely protect HF patients from developing type 2 diabetes.


Assuntos
Diabetes Mellitus Tipo 2 , Abordagens Dietéticas para Conter a Hipertensão , Insuficiência Cardíaca , Hipertensão , Resistência à Insulina , Adulto , Diabetes Mellitus Tipo 2/diagnóstico , Dieta , Feminino , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/epidemiologia , Insuficiência Cardíaca/prevenção & controle , Humanos , Hipertensão/diagnóstico , Inquéritos Nutricionais
5.
Diabetes Res Clin Pract ; 184: 109191, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35041861

RESUMO

AIMS: This study estimated national prevalence and trends of diagnosed and undiagnosed type 2 diabetes mellitus (T2DM) and prediabetes among heart failure (HF) patients in the U.S. METHODS: This cross-sectional study included 527 participants aged 20+ years with a diagnosis of HF, using data from the National Health and Nutrition Examination Survey 2005-2016. We assessed prevalence estimates of diagnosed and undiagnosed T2DM and prediabetes stratified by age-standardized sociodemographic and health characteristics. Trends of T2DM and prediabetes prevalence were examined using logistic regressions. RESULTS: Prevalence rates of diagnosed and undiagnosed T2DM among HF patients were 34.7% (95% confidence interval (CI), 29.2-40.3%) and 12.8% (95% CI, 9.2-16.9%), respectively. Prediabetes affected 39.1% (95% CI, 33.6-44.9%) of HF patients. Prevalence estimates of diagnosed T2DM were significantly different between non-Hispanic White (20.1% [95% CI, 13.5-27.6%]) and Hispanic participants (52.1% [95% CI, 35.9-68.0%]) (P < 0.001). The prevalence of T2DM and prediabetes did not significantly change between 2005 and 2016. CONCLUSIONS: Prevalence rates of T2DM and prediabetes among community-dwelling HF patients in the U.S. remained high between 2005 and 2016. Prevention of and targeted intervention for T2DM among at-risk HF patients is needed, particularly among those of Hispanic origin.


Assuntos
Diabetes Mellitus Tipo 2 , Diabetes Mellitus , Insuficiência Cardíaca , Estado Pré-Diabético , Adulto , Estudos Transversais , Diabetes Mellitus/epidemiologia , Diabetes Mellitus Tipo 2/diagnóstico , Diabetes Mellitus Tipo 2/epidemiologia , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/epidemiologia , Humanos , Vida Independente , Inquéritos Nutricionais , Estado Pré-Diabético/diagnóstico , Estado Pré-Diabético/epidemiologia , Prevalência , Estados Unidos/epidemiologia , Adulto Jovem
6.
Chem Commun (Camb) ; 57(99): 13594-13597, 2021 Dec 14.
Artigo em Inglês | MEDLINE | ID: mdl-34850783

RESUMO

Phthalocyanine ruthenium complexes were identified as red-light activatable catalysts for trifluoromethylation reactions. The red-light mediated chlorotrifluoromethylation of alkenes could proceed without any sacrificial reducing reagents. This reaction exhibited good compatibility with a blue-light-absorbing substrate, while under irradiation with blue light, i.e., under traditional photoreaction conditions, this substrate decomposed completely.

7.
Curr Atheroscler Rep ; 23(4): 13, 2021 02 17.
Artigo em Inglês | MEDLINE | ID: mdl-33594492

RESUMO

PURPOSE OF REVIEW: This review aims to discuss recent evidence and controversies regarding nutrition as a treatment modality for heart failure (HF) patients. RECENT FINDINGS: Adequate nutrition is known to promote health-related quality of life by addressing malnutrition and promoting optimal functioning among older adults and has an established role in the prevention of HF; however, evidence is limited on the effects of nutrition as a treatment modality in HF. While guidance of sodium restriction to address fluid overload is an ongoing debate among experts, evidence from case studies and small clinical trials suggest a positive impact of plant-based and Dietary Approaches to Stop Hypertension (DASH) dietary patterns on HF-related pathophysiology, quality of life, hospital admissions, and mortality. More clinical trials are needed to establish an evidence base to support dietary management strategies for patients with HF. Clinical and Translational Science Alliances (CTSAs) may provide infrastructure to overcome enrollment barriers.


Assuntos
Abordagens Dietéticas para Conter a Hipertensão , Insuficiência Cardíaca , Idoso , Promoção da Saúde , Insuficiência Cardíaca/terapia , Humanos , Estado Nutricional , Qualidade de Vida
8.
Biosci Biotechnol Biochem ; 85(4): 824-833, 2021 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-33589932

RESUMO

At the last stage of the blood coagulation cascade, thrombin plays a central role in the processing of fibrinogen for the polymerization and in the additional activation of Factor XIII for the stable cross-linking of fibrin. In addition, thrombin carries out possible multiple roles via processing or interaction with various functional proteins. Several studies conducted in order to elucidate additional physiological significance are ongoing. To clarify further significance of thrombin and to establish an associated disease model, we characterized the orthologue gene for medaka (Oryzias latipes), a research model fish. Tissue distribution of medaka prothrombin has been immunotechnically analyzed. Furthermore, thrombin-deficient medaka mutants were viably established by utilizing a genome-editing method. The established gene-deficient mutants exhibited retarded blood coagulation even in the heterozygous fish. Taking advantage of their ease of handling, this specific model is useful for further investigation in medical research areas on human coagulation diseases.


Assuntos
Transtornos da Coagulação Sanguínea/genética , Trombina/genética , Animais , Edição de Genes , Modelos Animais , Oryzias , Protrombina/metabolismo , Distribuição Tecidual
9.
Nutrients ; 11(11)2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31683657

RESUMO

The objective of this study was to examine the association between nutritional status and dietary intake in community-dwelling older adults with heart failure (HF). A cross-sectional analysis of NHANES III data was conducted. The analytic sample was comprised of n = 445 individuals aged 50+ years with congestive HF (54.4% male, 22.9% non-Hispanic Black, 43.8% low-income). Nutritional status was measured using the Prognostic Nutritional Index (PNI). Participants were classified by PNI quintiles with lower PNI scores indicating lower nutritional status. Participants in quintile 5 showed significantly greater intakes of energy, protein, vegetables, magnesium, zinc, copper, potassium, red meat, saturated fat, and sodium. In multivariate analyses, increased intake of red meat (ß = 0.253, p = 0.040) and vegetables (ß = 0.255, p = 0.038) was associated with significantly better nutritional status. In the absence of comprehensive nutritional guidance for HF patients, it appears that small increases in energy, protein (red meat), and vegetable consumption are associated with improved nutritional status.


Assuntos
Dieta/estatística & dados numéricos , Insuficiência Cardíaca , Estado Nutricional/fisiologia , Idoso , Idoso de 80 Anos ou mais , Comorbidade , Estudos Transversais , Feminino , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/epidemiologia , Humanos , Vida Independente , Masculino , Desnutrição , Pessoa de Meia-Idade , Inquéritos Nutricionais , Prognóstico
10.
PLoS One ; 13(8): e0201790, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30075024

RESUMO

Induction of apoptosis in response to various genotoxic stresses could block transmission of teratogenic mutations to progeny cells. The severity of biological effects following irradiation depends on the stage at which embryos are irradiated during embryogenesis. We reported previously that irradiation of medaka embryos 3 days post fertilization (dpf) with 10 Gy of gamma rays induced high incidence of apoptotic cells in the mid-brain, however, the embryos hatched normally and developed without apparent malformations. To determine the severity of biological effects following irradiation during a later period of embryogenesis, embryos of various developmental stages were irradiated with 15 Gy of gamma rays and examined for apoptotic induction at 24 h after irradiation in the brain, eyes and pharyngeal epithelium tissues, which are actively proliferating and sensitive to irradiation. Embryos irradiated at 3 dpf exhibited many apoptotic cells in these tissues, and all of them died due to severe malformations. In contrast, embryos irradiated at 5 dpf showed no apoptotic cells and subsequently hatched without apparent malformations. Embryos irradiated at 4 dpf had relatively low numbers of apoptotic cells compared to those irradiated at 3 dpf, thereafter most of them died within 1 week of hatching. In adult medaka, apoptotic cells were not found in these tissues following irradiation, suggesting that apoptosis occurs during a restricted time period of medaka embryogenesis throughout the life. No apoptotic cells were found in irradiated intestinal tissue, which is known to be susceptible to radiation damage in mammals, whereas many apoptotic cells were found in proliferating spermatogonial cells in the mature testis following irradiation. Taken together, with the exception of testicular tissue, the results suggest a limited period during medaka embryogenesis in which irradiation-induced apoptosis can occur.


Assuntos
Apoptose/efeitos da radiação , Embrião não Mamífero/efeitos da radiação , Desenvolvimento Embrionário/efeitos da radiação , Oryzias/embriologia , Animais , Animais Endogâmicos , Pontos de Checagem do Ciclo Celular/efeitos da radiação , Embrião não Mamífero/patologia , Embrião não Mamífero/ultraestrutura , Raios gama , Imageamento Tridimensional , Masculino , Microscopia Eletrônica , Tolerância a Radiação , Fatores de Tempo
11.
Appetite ; 125: 160-171, 2018 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-29447994

RESUMO

Family commensality, or meals eaten together with family members, is a key practice to understand the socio-cultural organization of eating and family lives. Yet empirical evidence is limited outside of western societies, which have different household structures, work styles, and socio-cultural constructions of the practice. This study examined frequencies of family commensality based on 242 surveys of Japanese adults aged between 20 and 85 in two metropolitan areas. Results showed that family commensality is less frequent not only among those living alone, but also among those living with only non-partners including adult children, parents, and non-family members, than among those living with partners. Full-time employment was associated with late dinner times on weekdays. Later weekday dinner times were strongly associated with reduced frequency of dinners together. Late dinners have become commonplace among full-time workers in postwar Japan, and the peak dinner time in Japan occurs later than in other developed countries. Thus, work and lifestyle constraints impacting schedules appear to influence the frequency of family commensality. Our results suggest that frequencies of family commensality are influenced by co-residents and work styles of participants rather than household sizes. The idea that reduction of household size drives reduction of family commensality may be biased by previous studies conducted in western countries where most people reside in either single or nuclear households. Our study highlights complex determinants of family commensality, beyond presence of other household members, and demonstrates a need for rigorous investigation of family commensality across cultures.


Assuntos
Emprego/psicologia , Características da Família , Família/psicologia , Comportamento Alimentar/psicologia , População Urbana/estatística & dados numéricos , Adulto , Idoso , Idoso de 80 Anos ou mais , Relações Familiares/psicologia , Feminino , Humanos , Japão , Masculino , Refeições , Pessoa de Meia-Idade , Fatores Socioeconômicos , Inquéritos e Questionários , Adulto Jovem
12.
Cancer Res ; 73(14): 4559-70, 2013 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-23720055

RESUMO

Tumor cell plasticity contributes to functional and morphologic heterogeneity. To uncover the underlying mechanisms of this plasticity, we examined glioma stem-like cells (GSC) where we found that the biologic interconversion between GSCs and differentiated non-GSCs is functionally plastic and accompanied by gain or loss of polycomb repressive complex 2 (PRC2), a complex that modifies chromatin structure. PRC2 mediates lysine 27 trimethylation on histone H3 and in GSC it affected pluripotency or development-associated genes (e.g., Nanog, Wnt1, and BMP5) together with alterations in the subcellular localization of EZH2, a catalytic component of PRC2. Intriguingly, exogenous expression of EZH2-dNLS, which lacks nuclear localization sequence, impaired the repression of Nanog expression under differentiation conditions. RNA interference (RNAi)-mediated attenuation or pharmacologic inhibition of EZH2 had little to no effect on apoptosis or bromodeoxyuridine incorporation in GSCs, but it disrupted morphologic interconversion and impaired GSC integration into the brain tissue, thereby improving survival of GSC-bearing mice. Pathologic analysis of human glioma specimens revealed that the number of tumor cells with nuclear EZH2 is larger around tumor vessels and the invasive front, suggesting that nuclear EZH2 may help reprogram tumor cells in close proximity to this microenvironment. Our results indicate that epigenetic regulation by PRC2 is a key mediator of tumor cell plasticity, which is required for the adaptation of glioblastoma cells to their microenvironment. Thus, PRC2-targeted therapy may reduce tumor cell plasticity and tumor heterogeneity, offering a new paradigm for glioma treatment.


Assuntos
Neoplasias Encefálicas/genética , Cromatina/genética , Cromatina/metabolismo , Glioblastoma/genética , Plasticidade Neuronal/genética , Complexo Repressor Polycomb 2/genética , Animais , Apoptose/genética , Proteína Morfogenética Óssea 5/genética , Proteína Morfogenética Óssea 5/metabolismo , Neoplasias Encefálicas/metabolismo , Neoplasias Encefálicas/patologia , Diferenciação Celular/genética , Linhagem Celular , Metilação de DNA , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Epigênese Genética , Feminino , Glioblastoma/metabolismo , Glioblastoma/patologia , Xenoenxertos , Histonas/genética , Histonas/metabolismo , Humanos , Lisina/genética , Lisina/metabolismo , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos NOD , Camundongos Nus , Camundongos SCID , Células-Tronco Neurais/metabolismo , Células-Tronco Neurais/patologia , Complexo Repressor Polycomb 2/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Proteína Wnt1/genética , Proteína Wnt1/metabolismo
13.
Biocontrol Sci ; 16(2): 63-7, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21719991

RESUMO

We investigated the antimicrobial activities of twelve derivatives of benzyl phenyl sulfide by using Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values against 10 microbial strains. These derivatives of benzyl phenyl sulfides were synthesized by means of the nucleophilic coupling reaction at our laboratory. MIC testing revealed that all synthetic derivatives of benzyl and 4-methoxybenzyl phenyl sulfides had no effect against the tested microbial strains. However, the compounds of 4-nitrobenzyl phenyl sulfide showed antimicrobial activity against many of the tested strains. Above all, 4-nitrobenzyl 4-chlorophenyl sulfide 11 exhibited the strongest and widest ranging inhibitory effects among the twelve synthetic compounds. We researched the antimicrobial activities of the coupling materials of sulfide. As a result, it was considered important for the expression of antimicrobial activities that the sulfide had a 4-nitrobenzyl group and 4-chlorophenyl group in the same molecule as in the case of benzyl phenyl sulfide.


Assuntos
Antibacterianos/farmacologia , Antifúngicos/farmacologia , Compostos de Benzil/farmacologia , Sulfetos/farmacologia , Antibacterianos/química , Antifúngicos/química , Compostos de Benzil/síntese química , Compostos de Benzil/química , Fungos/efeitos dos fármacos , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Relação Estrutura-Atividade , Sulfetos/síntese química , Sulfetos/química
14.
J Pathol ; 221(1): 96-105, 2010 May.
Artigo em Inglês | MEDLINE | ID: mdl-20217874

RESUMO

Although genomic copy number aberrations (CNAs) of gastric carcinoma at the advanced stage have already been extensively characterized by array comparative genomic hybridization (array CGH) analysis, those of gastric carcinoma in situ (CIS) are still poorly understood. Furthermore, no reports have demonstrated correlations between CNAs and histopathological features of gastric adenoma. In this study, we investigated CNAs of 20 gastric CISs (Vienna category 4.2) and 20 adenomas including seven low-grade adenomas (LGA; Vienna category 3) and 13 high-grade adenomas (HGA; Vienna category 4.1), using oligonucleotide-based array CGH. The most frequent aberrations in CIS were gains at 8q (85%) and 20q (50%), and losses at 5q (50%) and 17p (50%), suggesting that these CNAs are involved in the development of CIS. We found that the pattern of CNAs in HGA was quite different from that in LGA. The most frequent CNAs in HGA were gains at 8q (62%) and 7pq (54%), whereas those in LGA were gain at 7q21.3-q22.1 (57%) and loss at 5q (43%). Interestingly, gains at 8q and 7pq, both of which occurred most frequently in HGA, were not detected in any cases of LGA. Of note, 8q gain was detected most frequently in both HGA and CIS but was undetected in LGA. Since HGA is believed to have a higher risk of progression to invasive carcinoma than LGA, these data suggest that 8q gain is important for the malignant transformation of gastric adenoma.


Assuntos
Adenoma/genética , Carcinoma in Situ/genética , Neoplasias Gástricas/genética , Adenoma/patologia , Idoso , Idoso de 80 Anos ou mais , Carcinoma in Situ/patologia , Transformação Celular Neoplásica/genética , Aberrações Cromossômicas , Hibridização Genômica Comparativa , Progressão da Doença , Feminino , Perfilação da Expressão Gênica/métodos , Predisposição Genética para Doença , Humanos , Masculino , Pessoa de Meia-Idade , Modelos Genéticos , Neoplasias Gástricas/patologia
15.
Neural Netw ; 23(3): 356-64, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19716678

RESUMO

Gaussian mixture model (GMM) is widely used in many applications because it can approximate various forms of probability distributions. In this paper, we are concerned with GMM estimation problem using the variational Bayes (VB) method. In this approach, one can only find local optima because the free energy function of the problem is multimodal. In order to find better solutions, deterministic annealing was recently adapted to the VB method (DAVB method). In this paper, we offer an alternative approach to the DAVB method for GMM estimation problem. We propose a multi-directional search method from the primitive initial point (PIP), which is defined as the solution of the DAVB method at the highest temperature. Investigation on the curvature information of the original (not annealed) free energy function reveals that the PIP is a saddle point. An efficient multi-directional search strategy from the neighborhoods of the PIP is proposed using the eigen-analysis of the Hessian matrix. Numerical experiments using real data sets demonstrate the effectiveness of our method.


Assuntos
Teorema de Bayes , Redes Neurais de Computação , Distribuição Normal , Algoritmos , Fatores de Tempo
16.
Anal Sci ; 24(2): 219-23, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18270412

RESUMO

A new visual colorimetry for trace antimony(V) based on ion-pair solid-phase extraction to a PTFE-type membrane filter with bis[2-(5-chloro-2-pyridylazo)-5-diethylaminophenolato]cobalt(III) ion ([Co(5-Cl-PADAP)(2)](+)) has been developed. Experiments showed that hexachloroantimonate(V) ion (SbCl(6)(-)) was adsorbed with [Co(5-Cl-PADAP)(2)](+) to the front surface of the PTFE filter. The adsorption of antimony(V) ion was promoted by the addition of lithium chloride as a source of chloride ion. The excess reagent of [Co(5-Cl-PADAP)(2)](+) was eluted by rinsing with a 10 wt% methanol aqueous solution. In this case, the slow rate of the hydrolysis reaction of SbCl(6)(-) and the difference of the hydrophobicity of the ion pairs were important for adsorption and separation with a PTFE-type membrane filter. The antimony(V) concentration was determined through a visual comparison with a standard series. The visual detection limit was 0.10 microg. The calibration curve assessed with the reflection spectrometric responses at 580 nm was linear in the concentration range of 0.10 - 1.2 microg (r = 0.996). The proposed method has been applied to the determination of sub-microgram levels of antimony(V) ion in water samples.


Assuntos
Antimônio/análise , Membranas Artificiais , Compostos Organometálicos/química , Politetrafluoretileno/química , Extração em Fase Sólida/métodos , Adsorção , Colorimetria/instrumentação , Colorimetria/métodos , Hidrólise , Interações Hidrofóbicas e Hidrofílicas , Cloreto de Lítio/química , Metanol/química , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Soluções/química , Propriedades de Superfície , Água/química
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