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1.
Inorg Chem ; 63(11): 5040-5051, 2024 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-38428017

RESUMO

The effect of Eu doping in the Tsai quasicrystal (QC) GdCd7.88 and its periodic 1/1 approximant crystal (AC) GdCd6 are investigated. This represents the first synthesis of Eu-containing stable QC samples, where three samples with the final composition Gd1-xEuxCd7.6±α at Eu doping concentrations x = 0.06, 0.13, and 0.19 are obtained (α ∼ 0.2). They are compared to two 1/1 ACs with compositions Gd1-xEuxCd6 (x = 0.12, 0.16). In addition, a new type of 1/1 AC, differing only by the inclusion of extra Cd sites unique to the Eu4Cd25 1/1 AC, has been discovered and synthesized for the concentrations Gd1-xEuxCd6+δ (x = 0.25, 0.33, 0.45, 0.69, 0.73, and 0 < δ ≤ 0.085). Due to the preferred cube morphology of its single grains, we refer to them as c-type 1/1 ACs and to the conventional standard ones as s-type. In both QCs and s-type ACs, the Eu content appears to saturate at a concentration of ∼20%. On the other hand, any Gd| Eu ratio is allowed in the c-type ACs, varying continuously between GdCd6 and Eu4Cd25. We describe and contrast the changes in composition, atomic structure, specific heat, and magnetic properties induced by Eu doping in the quasicrystalline phase and the s-type and c-type 1/1 ACs. By comparing our results to the literature data, we propose that the occupancy of the extra Cd sites can be used to predict the stability of Tsai-type quasicrystalline phases.

2.
Inorg Chem ; 62(36): 14668-14677, 2023 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-37642644

RESUMO

Gd14AuxAl86-x Tsai-type 1/1 quasicrystal approximants (ACs) exhibit three magnetic orders that can be finely tuned by the valence electron concentration (e/a ratio). This parameter has been considered to be crucial for controlling the long-range magnetic order in quasicrystals (QCs) and ACs. However, the nonlinear trend of the lattice parameter as a function of Au concentration suggests that Gd14AuxAl86-x 1/1 ACs are not following a conventional solid solution behavior. We investigated Gd14AuxAl86-x samples with x values of 52, 53, 56, 61, 66, and 73 by single-crystal X-ray diffraction. Our analysis reveals that increasing Au/Al ordering with increasing x leads to distortions in the icosahedral shell built of the Gd atoms and that trends observed in the interatomic Gd-Gd distances closely correlate with the magnetic property changes across different x values. Our results demonstrate that the e/a ratio alone may be an oversimplified concept for investigating the long-range magnetic order in 1/1 ACs and QCs and that the mixing behavior of the nonmagnetic elements Au and Al plays a significant role in influencing the magnetic behavior of the Gd14AuxAl86-x 1/1 AC system. These findings will contribute to improved understanding towards tailoring magnetic properties in emerging materials.

3.
Toxins (Basel) ; 13(12)2021 12 07.
Artigo em Inglês | MEDLINE | ID: mdl-34941711

RESUMO

Cardiovascular disease (CVD) is the leading cause of mortality in diabetes mellitus (DM). Immunomodulatory dysfunction is a primary feature of DM, and the emergence of chronic kidney disease (CKD) in DM abruptly increases CVD mortality compared with DM alone. Endothelial injury and the accumulation of uremic toxins in the blood of DM/CKD patients are known mechanisms for the pathogenesis of CVD. However, the molecular factors that cause this disproportional increase in CVD in the DM/CKD population are still unknown. Since long non-protein-coding RNAs (lncRNAs) play an important role in regulating multiple cellular functions, we used human endothelial cells treated with high glucose to mimic DM and with the uremic toxin indoxyl sulfate (IS) to mimic the endothelial injury associated with CKD. Differentially expressed lncRNAs in these conditions were analyzed by RNA sequencing. We discovered that lnc-SLC15A1-1 expression was significantly increased upon IS treatment in comparison with high glucose alone, and then cascaded the signal of chemokines CXCL10 and CXCL8 via sponging miR-27b, miR-297, and miR-150b. This novel pathway might be responsible for the endothelial inflammation implicated in augmenting CVD in DM/CKD and could be a therapeutic target with future clinical applications.


Assuntos
Células Endoteliais/metabolismo , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Indicã/genética , Indicã/metabolismo , MicroRNAs/metabolismo , Insuficiência Renal Crônica/induzido quimicamente , Toxinas Biológicas/toxicidade , Adulto , Idoso , Idoso de 80 Anos ou mais , Doenças Cardiovasculares/complicações , Doenças Cardiovasculares/mortalidade , Quimiocina CXCL10/genética , Quimiocina CXCL10/metabolismo , Diabetes Mellitus Tipo 2/complicações , Feminino , Regulação da Expressão Gênica , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Transportador 1 de Peptídeos/genética , Transportador 1 de Peptídeos/metabolismo , Insuficiência Renal Crônica/genética , Insuficiência Renal Crônica/metabolismo , Regulação para Cima
4.
J Microbiol Immunol Infect ; 53(5): 682-689, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31859164

RESUMO

BACKGROUND/PURPOSE: Antimicrobial resistance in Taiwan has been on the rise for two decades. The implementation of pneumococcal conjugate vaccination (PCV13) and enhanced antimicrobial control (2013-2015) by the government may have changed the antibiotic resistance. METHODS: Four respiratory pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Streptococcus pyogenes, and Moraxella catarrhalis) isolated in a single medical center during 2008-2017 were studied. We defined three temporal stages: (a) the first era (2008-2012), prior to implementation of the national immunization program (PCV13 vaccination), (b) the second era (2013-2015), during which an enhanced antibiotic control strategy was implemented, and (c) the third era (2016-2017), after implementation. Antimicrobial drug sensitivities were collected from two other hospitals: one from east Taiwan, one from west-central Taiwan. RESULTS: S. pneumoniae was frequently isolated during the first era. It declined progressively during the second era of PCV13 vaccination. S. pyogenes and M. catarrhalis were not frequently isolated. The drug susceptibility of S. pneumoniae to ceftriaxone and vancomycin remained high. The antimicrobial susceptibility of H. influenzae to amoxillin/clavulante declined over the three temporal stages, from 91.9%-79.5%-58.5% (all p < 0.05). CONCLUSION: Antimicrobial resistance of H. influenzae increased during the latter part of the study period. The PCV13 vaccination program reduced the invasive pneumococcal disease and reduced the stress on the emergent drug resistance. This enhanced antibiotic control strategy was effective in terms of nosocomial drug resistance but not for community-associated pathogens.


Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana/efeitos dos fármacos , Vacinas Pneumocócicas/imunologia , Streptococcus pneumoniae/efeitos dos fármacos , Adolescente , Criança , Pré-Escolar , Feminino , Haemophilus influenzae/efeitos dos fármacos , Haemophilus influenzae/isolamento & purificação , Humanos , Programas de Imunização , Masculino , Testes de Sensibilidade Microbiana , Moraxella catarrhalis/efeitos dos fármacos , Moraxella catarrhalis/isolamento & purificação , Infecções Pneumocócicas/tratamento farmacológico , Infecções Pneumocócicas/prevenção & controle , Streptococcus pneumoniae/isolamento & purificação , Streptococcus pyogenes/efeitos dos fármacos , Streptococcus pyogenes/isolamento & purificação , Taiwan , Vacinação
5.
Health Policy ; 124(1): 89-96, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31699446

RESUMO

Reducing low-value care is a top priority in health care. However, how prospective payment methods such as diagnosis-related group (DRG) payment scheme reduce the use of low-value services is unclear. This study aimed to assess frequency of low-value preoperative testing services among surgical inpatients over time and to investigate whether the 2010 Tw-DRG policy has reduced utilization of these services under the National Health Insurance program in Taiwan. The nationwide National Health Insurance claims data in Taiwan from 2008 to 2013 were used. The difference-in-differences (DID) method was adopted. Utilization of three low-value preoperative testing services (chest x-ray, echocardiogram, and stress testing) were assessed. The prevalence of the three preoperative tests ranged from 0.13 per 100 admissions (preoperative stress testing) to 78.12 per 100 admissions (preoperative chest x-ray). Following the implementation of the Tw-DRG policy, the predicted probability of low-value care use was significantly reduced from 67.91% to 64.93% in the DRG group but remained relatively stable in the comparison group (from 69.44% to 68.43%) in 2010. The use of three selected preoperative tests had only a minor temporary reduction in 2010, but later increased over time. The 2010 Tw-DRG policy did not significantly moderate the growth of low-value preoperative use. Hospital financial incentives alone may be insufficient for reducing the provision of low-value care.


Assuntos
Atenção à Saúde/economia , Grupos Diagnósticos Relacionados/economia , Hospitalização , Pacientes Internados , Programas Nacionais de Saúde , Aceitação pelo Paciente de Cuidados de Saúde , Humanos , Taiwan
6.
Mol Med ; 25(1): 5, 2019 02 13.
Artigo em Inglês | MEDLINE | ID: mdl-30760202

RESUMO

BACKGROUND: Damage to the endothelium due to ischemia reperfusion injury (IRI) leads to a disruption of the microvasculature, which could be influenced by angiopoietin 1 via its effects on endothelium. We investigated the physiological and therapeutic roles of angiopoietin 1 in renal IRI using angiopoietin 1 knockout and over-expression mice. METHODS: Renal IRI was induced by clamping the right renal artery seven days after left uninephrectomy for 25 min followed by reperfusion. A whole body angiopoietin 1 knockout was achieved by induction with tamoxifen. The renal tubule over-expression of angiopoietin 1 was induced by doxycycline. RESULTS: In the normal mice, the renal expression of angiopoietin 1 increased 7 days to 14 days after IRI. The angiopoietin 1 knockout caused a delay in the recovery of renal function, less tubular regeneration and more residual tubular necrosis. The endothelial density was lower and the VE-cadherin protein loss was greater in the knockout mice. The over-expression of angiopoietin 1 attenuated the tubular necrosis and renal function impairment 1 and 3 days after IRI. The loss of the endothelium was ameliorated in the over-expression mice. This protective effect was associated with the up-regulation of the gene expression of epidermal growth factor, hepatocyte growth factor, and insulin like growth factor-1 and less tubular apoptosis. The over-expression of angiopoietin 1 stimulated tumor necrosis factor-α, C-C chemokine receptor type 2 and CX3C chemokine receptor 1 inflammatory gene expression, but did not influence macrophage infiltration. CONCLUSIONS: Altogether, the augmentation and downregulation of angiopoietin 1 attenuated renal damage and impaired renal recovery, respectively, by influencing the survival/regeneration of the endothelium. The manipulation of angiopoietin 1 represents a novel therapeutic approach for the treatment of ischemic kidney injury.


Assuntos
Injúria Renal Aguda/fisiopatologia , Angiopoietina-1/fisiologia , Endotélio/fisiologia , Traumatismo por Reperfusão/fisiopatologia , Animais , Regulação para Baixo , Túbulos Renais/patologia , Túbulos Renais/fisiologia , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Regeneração
7.
Ann Transl Med ; 7(22): 693, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31930094

RESUMO

Extracellular vesicles (EVs) of mesenchymal stem cells (MSCs) are secreted by live cells and possess the same regenerative potential and immunomodulatory ability as their parental cells. Clinical applications of MSC-EVs could overcome the shortage of MSCs for treatment of cancer and other diseases and impact the field of regenerative medicine from cellular to acellular therapy. For use of MSC-EVs as a clinical agent, various engineered EVs have been manufactured and their therapeutic effects on various diseases demonstrated in preclinical studies and clinical trials. However, MSC-EVs are heterogeneous, and many of their characteristics are still unknown. Many barriers still need to be surmounted before MSC-EVs can be used as biomedical agents.

8.
Med Care ; 54(11): 977-983, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27547944

RESUMO

BACKGROUND: Several studies have investigated the effects of pay-for-performance (P4P) initiatives. However, little is known about whether patients with multiple chronic conditions (MCC) would benefit from P4P initiatives similarly to patients without MCC. OBJECTIVES: The objective of this study was to compare the effects of the diabetes mellitus pay-for-performance (DM-P4P) program on the quality of diabetic care between type 2 diabetic patients with and without MCC. METHODS: This study used data from Taiwan's Longitudinal Health Insurance Database 2005. Of this cohort, 52,276 diabetic patients were identified. To address potential selection bias between the intervention and comparison groups, the propensity score matching method was used. Generalized estimating equations were applied to analyze the difference-in-difference model to examine the effect of the intervention, the DM-P4P program. RESULTS: The disease-specific DM-P4P program had positive impacts on process and outcome indicators of health care quality regardless of patients' MCC status. Diabetic patients with MCC experienced a significantly larger decrease in the admission rate of diabetes-related ambulatory care sensitive conditions after the P4P enrollment over time compared with patients without MCC. CONCLUSIONS: The positive impacts on use of diabetes-related services were comparable between diabetic patients with and without MCC. Most importantly, for MCC patients, the disease-specific DM-P4P program had a stronger positive impact on health outcomes. Hence, the commonly observed phenomenon of "cherry picking" in implementing P4P strategies may lead to disparities in the quality of diabetic care between diabetic patients with and without MCC.


Assuntos
Complicações do Diabetes/terapia , Diabetes Mellitus Tipo 2/terapia , Reembolso de Incentivo/estatística & dados numéricos , Adulto , Idoso , Doença Crônica/terapia , Diabetes Mellitus Tipo 2/complicações , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Qualidade da Assistência à Saúde/estatística & dados numéricos , Reembolso de Incentivo/normas , Resultado do Tratamento , Adulto Jovem
9.
ACS Appl Mater Interfaces ; 6(13): 10667-78, 2014 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-24921939

RESUMO

In this study, we developed a simple and powerful method to fabricate flexible and lightweight graphene-based composites that provide high electromagnetic interference (EMI) shielding performance. Electrospun waterborne polyurethane (WPU) that featured sulfonate functional groups was used as the polymer matrix, which was light and flexible. First, graphene oxide (GO)/WPU composites were prepared through layer-by-layer (L-b-L) assembly of two oppositely charged suspensions of GO, the cationic surfactant (didodecyldimethylammonium bromide, DDAB)-adsorbed GO and intrinsic negatively charged GO, depositing on the negatively charged WPU fibers. After the L-b-L assembly cycles, the GO bilayers wrapped the WPU fiber matrix completely and revealed fine connections guided by the electrospun WPU fibers. Then, we used hydroiodic acid (HI) to obtain highly reduced GO (r-GO)/WPU composites, which exhibited substantially enhanced electrical conductivity (approximately 16.8 S/m) and, moreover, showed a high EMI-shielding effectiveness (approximately 34 dB) over the frequency range from 8.2 to 12.4 GHz.

10.
J Bone Miner Res ; 29(3): 676-84, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23929760

RESUMO

Acute kidney injury (AKI) has a negative impact on long-term renal function and prognosis. However, the association between acute renal dysfunction and long-term effects on bone disorders has not yet been characterized. Using a population-based cohort study, we aimed to evaluate associations between AKI and long-term effects on bone fractures. We identified relevant data of all hospitalized patients aged >18 years with histories of dialysis-requiring AKI, with subsequent recovery and discharge, from the claim records of the Taiwan National Health Insurance database between 2000 and 2008. We determined long-term de novo bone fracture and all-cause mortality after patients' index-hospitalization discharge using propensity score-adjusted Cox proportional hazard model. Varying-time models were used to adjust for long-term effects of end-stage renal disease (ESRD) on main outcomes. Among 448 AKI patients who had dialysis and survived 90 days after index-hospitalization discharge without reentering dialysis, 273 were male (60.9%) with a mean age of 61.4 ± 16.6 years. Controls included 1792 hospitalized patients without AKI, dialysis, or bone fracture history. In the AKI recovery group, bone fracture incidence was 320 per 10,000 person-years and hazard ratio (HR) of long-term bone fracture was 1.25 (p = 0.049) compared with the control group, independent of subsequent ESRD status (HR = 1.55; p = 0.01). Both AKI recovery status (HR = 2.31; p < 0.001) and time varying factor of bone fracture (HR = 1.43; p < 0.001) were independent predictors of mortality compared with controls. In conclusion, AKI requiring temporary dialysis independently increases long-term risk of bone fracture, regardless of subsequent progression to ESRD. Long-term bone fractures may negatively impact patient mortality.


Assuntos
Injúria Renal Aguda/complicações , Fraturas Ósseas/complicações , Diálise Renal , Injúria Renal Aguda/terapia , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Modelos de Riscos Proporcionais , Taiwan
11.
Environ Manage ; 47(1): 56-66, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20936282

RESUMO

Cetacean-focused tourism in Taiwan has grown rapidly since 1997. This development, measured in terms of both number of tour boats and visitors, has resulted in many resource management challenges stemming from the absence of regulation and scientific data. To fill this void in empirical evidence, we used 464 sighting records from 2002 to 2005 to model the impact of cetacean-focused tourism. Cox proportional hazard analysis indicated cetacean avoidance responses to cetacean watching boats were strongly associated with pod size, mother-calf pairs, and cetacean-vessel distances. Mother-calf pairs abandoned their avoidance tactic by 55% compared to noncalf groups when tour boats approached. Second, the hazard ratio of abundance was 0.996, suggesting that the odds of encountering avoidance responses by the cetaceans decreased by 42% for every 100-member increase in the cetacean pod size. Last, distances maintained by boats from the cetaceans was positively related to avoidance responses (i.e., less avoidance behavior with closer interaction). Based on our findings, we have the following recommendations: (a) limit vessels from approaching mothers with calves, (b) limit vessels from approaching small groups of cetaceans, (c) reduced avoidance behavior to boat traffic may be a red flag for potential long-term disturbance, and (d) apply the "precautionary principle" based on the best scientific information available in cetacean-based tourism in Taiwan. These recommendations will help contribute to the sustainable development of cetacean-focused tourism in Taiwan.


Assuntos
Comportamento Animal , Cetáceos , Conservação dos Recursos Naturais , Modelos Teóricos , Animais , Reação de Fuga , Feminino , Humanos , Recreação , Reprodução , Navios , Comportamento Social , Taiwan , Viagem
12.
Opt Express ; 17(20): 18083-92, 2009 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-19907598

RESUMO

This paper reports a simple and effective ultrasonic embossing method which enables the rapid fabrication of dual-side surface-relief plastic diffusers with various cross angles. Metallic master molds bearing microstructures are fabricated using a tungsten carbide turning machine. A 1500-Watt ultrasonic vibrator with an output frequency of 20 kHz was used to replicate the microstructure onto 1 mm thick PMMA and PET films in the experiments. During ultrasonic embossing, the ultrasonic energy is converted into heat through intermolecular friction at the master mold/plastic plate interface due to asperities to melt the thermoplastic at the interface and thereby to replicate the microstructure. Under the proper processing conditions, high-performance dual-sided plastic diffusers of various cross-angles can be successfully fabricated. The proposed method shows great potential for fast fabrication of micro-optical components due to its simplicity and versatility.


Assuntos
Lentes , Membranas Artificiais , Refratometria/instrumentação , Sonicação/métodos , Desenho Assistido por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Luz , Reprodutibilidade dos Testes , Espalhamento de Radiação , Sensibilidade e Especificidade
13.
Kidney Int ; 68(2): 760-5, 2005 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16014053

RESUMO

BACKGROUND: Sexual function is one aspect of physical functioning. Sexual dysfunction, no matter the etiology, could cause distress. In female hemodialysis patients, sexual problems have often been neglected in clinical performance and research. METHODS: We conducted this study by use of self-reported questionnaires. A total of 578 female hemodialysis patients in northern Taiwan were included in this study. Demographic data, comorbid diseases, medications in use, biochemical, and hematologic parameters were analyzed. All patients were asked to complete by themselves three questionnaires: (1) the Index of Female Sexual Function (IFSF) to assess sexual function; (2) the Beck Depression Inventory (BDI) (Chinese version) to rate the severity of depressive symptoms; and (3) the 36-item Short Form Health Survey Questionnaire (SF-36, Taiwan Standard Version 1.0) to survey their quality of life. RESULTS: A total of 138 female patients were enrolled into further analysis. The mean age was 48.7 +/- 11.2 years old. The mean IFSF score was 24.5 +/- 9.3. Age, BDI score, and serum triglyceride levels were the independent factors of dysfunction in each sexual functional dimension. Patients with higher IFSF scores had significantly higher scores in physical functioning and mental health (P= 0.007 and 0.018, respectively). Patients with higher intercourse satisfaction had significantly higher general health scores (P= 0.001). CONCLUSION: Sexual dysfunction is frequent in the female hemodialysis population. It is strongly associated with increasing age, dyslipidemia, and depression. The subjects with sexual dysfunction had poorer quality of life. The diagnosis and treatment of sexual dysfunction should be included in the clinical assessment.


Assuntos
Falência Renal Crônica/epidemiologia , Diálise Renal/estatística & dados numéricos , Disfunções Sexuais Fisiológicas/epidemiologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Comorbidade , Depressão/epidemiologia , Feminino , Humanos , Falência Renal Crônica/psicologia , Falência Renal Crônica/terapia , Modelos Lineares , Pessoa de Meia-Idade , Prevalência , Qualidade de Vida , Disfunções Sexuais Fisiológicas/psicologia , Inquéritos e Questionários
14.
Inorg Chem ; 44(2): 382-92, 2005 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-15651885

RESUMO

For this study, the N'-monoamide derivatives of TTDA (3,6,10-tri(carboxymethyl)-3,6,10-triazadodecanedioic acid), N'-methylamide (TTDA-MA), N'-benzylamide (TTDA-BA), and N'-2-methoxybenzylamide (TTDA-MOBA), were synthesized. Their protonation constants and stability constants (log K(ML)'s) formed with Ca(2+), Zn(2+), Cu(2+), and Gd(3+) were determined by potentiometric titration in 0.10 M Me(4)NCl at 25.0 +/- 0.1 degrees C. The relaxivity values of [Gd(TTDA-MA)](-), [Gd(TTDA-BA)](-), and [Gd(TTDA-MOBA)](-) remained constant with respect to pH changes over the range 4.5-12.0. The (17)O NMR chemical shift of H(2)O induced by [Dy(TTDA-MA)(H(2)O)](-) at pH 6.80 showed 0.9 inner-sphere water molecules. Water proton relaxivity values for [Gd(TTDA-MA)(H(2)O)](-), [Gd(TTDA-BA)(H(2)O)](-), and [Gd(TTDA-MOBA)(H(2)O)](-) at 37.0 +/- 0.1 degrees C and 20 MHz are 3.89, 4.21, and 4.25, respectively. The water-exchange lifetime (tau(M)) and rotational correlation time (tau(R)) of [Gd(TTDA-MA)(H(2)O)](-), [Gd(TTDA-BA)(H(2)O)](-), and [Gd(TTDA-MOBA)(H(2)O)](-) are obtained from reduced the (17)O relaxation rate and chemical shifts of H(2)(17)O. The (2)H NMR longitudinal relaxation rates of the deuterated diamagnetic lanthanum complexes for the rotational correlation time were also thoroughly investigated. The water-exchange rates (K(298)(ex) for [Gd(TTDA-MA)(H(2)O)](-), [Gd(TTDA-BA)(H(2)O)](-), and [Gd(TTDA-MOBA)(H(2)O)](-) are lower than that of [Gd(TTDA)(H(2)O)](2)(-) but significantly higher than those of [Gd(DTPA)(H(2)O)](2)(-) and [Gd(DTPA-BMA)(H(2)O)]. The rotational correlation times for [Gd(TTDA-BA)(H(2)O)](-) and [Gd(TTDA-MOBA)(H(2)O)](-) are significantly longer than those of [Gd(TTDA)(H(2)O)](2)(-) and [Gd(DTPA)(H(2)O)](2)(-) complexes. The marked increase of the relaxivity of [Gd(TTDA-BA)(H(2)O)](-) and [Gd(TTDA-MOBA)(H(2)O)](-) results mainly from their longer rotational correlation time. The noncovalent interaction between human serum albumin (HSA) and [Gd(TTDA-BA)(H(2)O)](-) and [Gd(TTDA-MOBA)(H(2)O)](-) complexes containing a hydrophobic substituent was investigated by measuring the water proton relaxation rate of the aqueous solutions. The binding association constant (K(A)) values are 1.0 +/- 0.2 x 10(3) and 1.3 +/- 0.2 x 10(3) M(-1) for [Gd(TTDA-BA)(H(2)O)](-) and [Gd(TTDA-MOBA)(H(2)O)](-), which indicates a stronger interaction of [Gd(TTDA-BA)(H(2)O)](-) and [Gd(TTDA-MOBA)(H(2)O)](-) with HSA.


Assuntos
Amidinas/química , Amidinas/síntese química , Gadolínio/química , Compostos Organometálicos/química , Compostos Organometálicos/síntese química , Catálise , Indicadores e Reagentes , Ligantes , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Termodinâmica
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