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1.
Sci Rep ; 13(1): 13451, 2023 Aug 18.
Artículo en Inglés | MEDLINE | ID: mdl-37596292

RESUMEN

The role of spin-orbit interaction has been recently reconsidered in high-[Formula: see text] cuprates, stimulated by the recent experimental observations of spin-polarized electronic states. However, due to the complexity of the spin texture reported, the origin of the spin polarization in high-[Formula: see text] cuprates remains unclear. Here, we present the spin- and angle-resolved photoemission spectroscopy (ARPES) data on the facing momentum points that are symmetric with respect to the [Formula: see text] point, to ensure the intrinsic spin nature related to the initial state. We consistently found the very weak spin polarization only along the nodal direction, with no indication of spin-splitting of the band. Our findings thus call for a revision of the simple application of the spin-orbit interaction, which has been treated within the standard framework of the Rashba interaction in high-[Formula: see text] cuprates.

2.
Phys Rev Lett ; 122(7): 076402, 2019 Feb 22.
Artículo en Inglés | MEDLINE | ID: mdl-30848650

RESUMEN

Topological semimetals materialize a new state of quantum matter where massless fermions protected by a specific crystal symmetry host exotic quantum phenomena. Distinct from well-known Dirac and Weyl fermions, structurally chiral topological semimetals are predicted to host new types of massless fermions characterized by a large topological charge, whereas such exotic fermions are yet to be experimentally established. Here, by using angle-resolved photoemission spectroscopy, we experimentally demonstrate that a transition-metal silicide CoSi hosts two types of chiral topological fermions, a spin-1 chiral fermion and a double Weyl fermion, in the center and corner of the bulk Brillouin zone, respectively. Intriguingly, we found that the bulk Fermi surfaces are purely composed of the energy bands related to these fermions. We also find the surface states connecting the Fermi surfaces associated with these fermions, suggesting the existence of the predicted Fermi-arc surface states. Our result provides the first experimental evidence for the chiral topological fermions beyond Dirac and Weyl fermions in condensed-matter systems, and paves the pathway toward realizing exotic electronic properties associated with unconventional chiral fermions.

3.
Sci Rep ; 8(1): 17431, 2018 Nov 27.
Artículo en Inglés | MEDLINE | ID: mdl-30479359

RESUMEN

Angle-resolved photoemission spectroscopy (ARPES) is a powerful experimental technique in materials science, as it can directly probe electronic states inside solids in energy (E) and momentum (k) space. As an advanced technique, spatially-resolved ARPES using a well-focused light source (high-resolution ARPES microscopy) has recently attracted growing interests because of its capability to obtain local electronic information at micro- or nano-metric length scales. However, there exist several technical challenges to guarantee high precision in determining translational and rotational positions in reasonable measurement time. Here we present two methods of obtaining k-space mapping and real-space imaging in high-resolution ARPES microscopy. One method is for k-space mapping measurements that enables us to keep a target position on a sample surface during sample rotation by compensating rotation-induced displacements (tracing acquisition method). Another method is for real-space imaging measurements that significantly reduces total acquisition time (scanning acquisition method). We provide several examples of these methods that clearly indicate higher accuracy in k-space mapping as well as higher efficiency in real-space imaging, and thus improved throughput of high-resolution APRES microscopy.

4.
J Phys Condens Matter ; 29(47): 475502, 2017 Nov 29.
Artículo en Inglés | MEDLINE | ID: mdl-28891807

RESUMEN

Electronic structures of ferromagnetic heavy fermion Yb compounds of YbPdSi, YbPdGe, and YbPtGe are studied by photoelectron spectroscopy around the Yb 4d-4f resonance, resonant x-ray emission spectroscopy at the Yb L 3 absorption edge, and density functional theory combined with dynamical mean field theory calculations. These compounds all have a temperature-independent intermediate Yb valence with large [Formula: see text] and small [Formula: see text] components. The magnitude of the Yb valence is evaluated to be YbPtGe [Formula: see text] YbPdGe [Formula: see text] YbPdSi, suggesting that YbPtGe is the closest to the quantum critical point among the three Yb compounds. Our results support the scenario of the coexistence of heavy fermion behavior and ferromagnetic ordering which is described by a magnetically-ordered Kondo lattice where the magnitude of the Kondo effect and the RKKY interaction are comparable.

5.
Ultramicroscopy ; 182: 85-91, 2017 11.
Artículo en Inglés | MEDLINE | ID: mdl-28666139

RESUMEN

We have developed a laser-based scanning angle-resolved photoemission spectroscopy system (µ-ARPES) equipped with a high precision 6-axis control system, realizing not only high-resolution photoemission spectroscopy in energy and momentum, but also spatial resolution of a µm scale. This enables our µ-ARPES system to probe fine details of intrinsic electronic states near the Fermi level such as the superconducting gaps and lifetime broadening.

6.
J Phys Condens Matter ; 29(28): 285501, 2017 Jul 19.
Artículo en Inglés | MEDLINE | ID: mdl-28530634

RESUMEN

We have investigated the influence of metal adsorbates (sodium and cobalt) on the occupied and unoccupied electronic structure of MoS2(0 0 0 1) and WSe2(0 0 0 1), through a combination of both photoemission and inverse photoemission. The electronic structure is rigidly shifted in both the WSe2 and MoS2 systems, with either Na or Co adsorption, generally as predicted by accompanying density functional theory based calculations. Na adsorption is found to behave as an electron donor (n-type) in MoS2, while Co adsorption acts as an electron acceptor (p-type) in WSe2. The n-type transition metal dichalcogenide (MoS2) is easily doped more n-type with Na deposition while the p-type transition metal dichalcogenide (WSe2) is easily doped more p-type with Co deposition. The binding energy shifts have some correlation with the work function differences between the metallic adlayer and the transition metal dichalcogenide substrate.

7.
J Phys Condens Matter ; 28(34): 345503, 2016 09 01.
Artículo en Inglés | MEDLINE | ID: mdl-27362263

RESUMEN

The orbital symmetry of the band structure of 2H-WSe2(0 0 0 1) has been investigated by means of angle-resolved photoelectron spectroscopy (ARPES) and density functional theory (DFT). The WSe2(0 0 0 1) experimental band structure is found, by ARPES, to be significantly different for states of even and odd reflection parities along both the [Formula: see text]-[Formula: see text] and [Formula: see text]-[Formula: see text] lines, in good agreement with results obtained from DFT. The light polarization dependence of the photoemission intensities from the top of the valence band for bulk WSe2(0 0 0 1) is explained by the dominance of W 5[Formula: see text] states around the [Formula: see text]-point and W 5d xy states around the [Formula: see text]-point, thus dominated, respectively, by states of even and odd symmetry, with respect to the [Formula: see text]-[Formula: see text] line. The splitting of the topmost valence band at [Formula: see text], due to spin-orbit coupling, is measured to be 0.49 ± 0.01 eV, in agreement with the 0.48 eV value from DFT, and prior measurements for the bulk single crystal WSe2(0 0 0 1), albeit slightly smaller than the 0.513 ± 0.01 eV observed for monolayer WSe2.

8.
Nano Lett ; 15(6): 4013-8, 2015 Jun 10.
Artículo en Inglés | MEDLINE | ID: mdl-25996311

RESUMEN

Single-layer transition-metal dichalcogenides (TMDs) receive significant attention due to their intriguing physical properties for both fundamental research and potential applications in electronics, optoelectronics, spintronics, catalysis, and so on. Here, we demonstrate the epitaxial growth of high-quality single-crystal, monolayer platinum diselenide (PtSe2), a new member of the layered TMDs family, by a single step of direct selenization of a Pt(111) substrate. A combination of atomic-resolution experimental characterizations and first-principle theoretic calculations reveals the atomic structure of the monolayer PtSe2/Pt(111). Angle-resolved photoemission spectroscopy measurements confirm for the first time the semiconducting electronic structure of monolayer PtSe2 (in contrast to its semimetallic bulk counterpart). The photocatalytic activity of monolayer PtSe2 film is evaluated by a methylene-blue photodegradation experiment, demonstrating its practical application as a promising photocatalyst. Moreover, circular polarization calculations predict that monolayer PtSe2 has also potential applications in valleytronics.


Asunto(s)
Procesos Fotoquímicos , Platino (Metal)/química , Compuestos de Selenio/química , Semiconductores
9.
Clin Exp Nephrol ; 19(4): 661-8, 2015 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-25399058

RESUMEN

BACKGROUND: Dietary protein intake (PI) induces glomerular hyperfiltration and reduced dietary PI can be effective in preserving kidney function. However, there is limited information regarding the relationship between dietary PI and glomerular histological changes in chronic kidney disease. We investigated the relationship between changes in dietary PI and both the changes in creatinine clearance and glomerular histomorphometry in adult patients with IgA nephropathy (IgAN). METHODS: A total of 24 consecutive adult patients with biopsy-confirmed IgAN were enrolled and glomerular histomorphometric variables and clinical variables were investigated. The main clinical variables were differences in creatinine clearance (Ccr) (dCcr) and in PI (dPI) which were calculated by subtracting PI and Ccr values in patients on a controlled diet during hospitalization for kidney biopsy from the respective values in patients on daily diets as outpatients. These values of PI were estimated from urinary urea excretion measured by 24-h urine collection. The main renal histomorphometric variable was glomerular tuft area (GTA) (µm(2)). RESULTS: dCcr positively correlated with dPI (r = 0.726, P < 0.001). GTA correlated positively with dPI (r = 0.556, P = 0.013). Multiple regression analysis showed that dPI was independently associated with both dCcr and GTA. Additionally, GTA positively correlated with dietary PI as outpatients (r = 0.457, P = 0.043). CONCLUSION: Changes in dietary PI were associated with the changes in glomerular filtration rate. Furthermore, histomorphometric findings suggested that a greater dietary PI can affect the glomerular size at the time of the initial diagnostic biopsy for IgAN.


Asunto(s)
Proteínas en la Dieta/farmacología , Glomerulonefritis por IGA/fisiopatología , Glomérulos Renales/efectos de los fármacos , Adulto , Creatinina/orina , Femenino , Tasa de Filtración Glomerular , Glomerulonefritis por IGA/patología , Glomerulonefritis por IGA/orina , Humanos , Glomérulos Renales/patología , Masculino , Adulto Joven
10.
Blood Purif ; 38(2): 149-53, 2014.
Artículo en Inglés | MEDLINE | ID: mdl-25471451

RESUMEN

BACKGROUND/AIMS: Combining peritoneal dialysis (PD) and hemodialysis (HD) has been common treatment option in Japan. METHODS: In this retrospective, multicenter, observational study, the clinical characteristics and outcomes of 104 patients (57 ± 11 years, males 72%) who had switched from PD alone to combined therapy with PD and HD were studied. Clinical parameters were measured at baseline and after 3 months of combined therapy. RESULTS: At baseline, urine volume, dialysate-to-plasma ratio of creatinine (D/P Cr), and total Kt/V were 150 ml/day (range: 0-2,000 ml/day), 0.67 ± 0.11, and 1.8 ± 0.4, respectively. During the first 3 months of combined therapy, body weight, urine volume, serum creatinine level, and D/P Cr decreased, whereas hemoglobin levels increased. CONCLUSIONS: In patients where PD does not result in acceptable outcomes, combined therapy with PD and HD may have potential benefits in terms of dialysis adequacy and hydration status. Video Journal Club "Cappuccino with Claudio Ronco" at http://www.karger.com/?doi=368389


Asunto(s)
Creatinina/sangre , Fallo Renal Crónico/terapia , Diálisis Peritoneal , Anciano , Femenino , Soluciones para Hemodiálisis/química , Humanos , Fallo Renal Crónico/sangre , Fallo Renal Crónico/patología , Fallo Renal Crónico/fisiopatología , Masculino , Persona de Mediana Edad , Diálisis Renal , Estudios Retrospectivos , Urinálisis
11.
J Phys Condens Matter ; 26(45): 455501, 2014 Nov 12.
Artículo en Inglés | MEDLINE | ID: mdl-25301782

RESUMEN

We find a wave vector dependence of the band symmetries for MoS(2)(0 0 0 1) in angle-resolved photoemission. The band structures are found to be significantly different for states of even and odd reflection parities, despite the absence of true mirror plane symmetry away from Γ, the Brillouin zone center, along the line to the K point, at the Brillouin zone edge. Our measurements agree with density functional theory (DFT) calculations for each band symmetry, with the notable exception of the Mo 4d(x(2)-y(2)) contributions to the valence band structure of MoS(2)(0 0 0 1). The band structure is indicative of strong S 3p and Mo 4d hybridization. In particular, the top of the valence band is predominantly composed of Mo 4d(3z(2)-r(2)) derived states near Γ, whereas near K Mo 4d(x(2)-y(2)) as well as Mo 4d(xy) dominate. In contrast, the bottom of the valence band is dominated by Mo 5s and S 3p(z) contributions.

12.
J Phys Condens Matter ; 26(15): 155501, 2014 Apr 16.
Artículo en Inglés | MEDLINE | ID: mdl-24675644

RESUMEN

We report the experimental identification of a symmetry-protected surface state on Mo(1 1 2). The utilization of photon-energy- and polarization-dependent angle-resolved photoemission spectroscopy clearly demonstrates that this true surface state preserves its two-dimensional character despite the fact that it resides within the projection of the bulk bands along the ̅Γ-̅X line of the surface Brillouin zone. This surface state on Mo(1 1 2) exists due to the forbidden hybridization between the bulk and the surface states, each of which possesses different state symmetries within the crystal. The experimental identification of such a surface state possibly opens up pathways towards controlled manipulation between true surface states and the surface resonances (i.e. between two-dimensional and quasi-two-dimensional states) by breaking the symmetry of the crystal surface.


Asunto(s)
Molibdeno/química , Espectroscopía de Fotoelectrones , Fotones , Cristalización , Conformación Molecular , Propiedades de Superficie
13.
Sci Rep ; 3: 1930, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23722675

RESUMEN

Clarifying the coupling between electrons and bosonic excitations (phonons or magnetic fluctuations) that mediate the formation of Cooper pairs is pivotal to understand superconductivity. Such coupling effects are contained in the electron self-energy, which is experimentally accessible via angle-resolved photoemission spectroscopy (ARPES). However, in unconventional superconductors, identifying the nature of the electron-boson coupling remains elusive partly because of the significant band renormalization due to electron correlation. Until now, to quantify the electron-boson coupling, the self-energy is most often determined by assuming a phenomenological 'bare' band. Here, we demonstrate that the conventional procedure underestimates the electron-boson coupling depending on the electron-electron coupling, even if the self-energy appears to be self-consistent via the Kramers-Kronig relation. Our refined method explains well the electron-boson and electron-electron coupling strength in ruthenate superconductor Sr2RuO4, calling for a critical revision of the bosonic coupling strength from ARPES self-energy in strongly correlated electron systems.


Asunto(s)
Cobre/química , Conductividad Eléctrica , Electrones , Compuestos de Rutenio/química , Estroncio/química , Fenómenos Químicos , Fonones , Espectroscopía de Fotoelectrones , Termodinámica
14.
Nephrology (Carlton) ; 18(4): 285-91, 2013 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-23432763

RESUMEN

AIM: We investigated the handling of phosphate by end-stage kidneys and the contribution of residual renal function (RRF) to phosphate homeostasis in haemodialysis patients. METHODS: Blood and 24 h urinary specimens were obtained from 79 consecutive chronic haemodialysis patients with a urinary output greater than 100 mL/day. Thirty-five patients with a glomerular filtration rate (GFR) ≥ 3.0 mL/min were included as group A, and 44 patients with GFR < 3.0 mL/min as group B. Additionally, the whole dialysed fluids during a session of haemodialysis were collected from another nine patients. Concentrations of phosphate, creatinine, urea nitrogen, intact parathyroid hormone (iPTH) and fibroblast growth factor 23 (FGF-23) were measured. RESULTS: Twenty-four hour urinary phosphate excretion (UPE) was 283 ± 115 and 139 ± 57 mg/day (9.1 ± 3.5 and 4.5 ± 1.8 mmol/day) in groups A and B, respectively. Tubular reabsorption of phosphate (TRP) was 39.2 ± 13.3 and 31.7 ± 13.6% in groups A and B, respectively (P = 0.02). UPE significantly correlated with GFR (r = 0.85, P < 0.001) and PTH (r = 0.44, P < 0.001), but not with FGF-23, in the entire patient population. The correlation between UPE and intact PTH levels was absent in group B. Weekly UPE in group A was significantly greater (P < 0.001), while that in group B was similar to the amount of phosphate removed by a haemodialysis session. CONCLUSIONS: Urinary phosphate excretion by end-stage kidneys depends more on GFR than diminishing TRP. The action of PTH on the kidneys remains until GFR decreases to as low as 3 mL/min. Residual renal function plays a significant role in phosphate elimination, and it is possible that FGF-23 no longer acts effectively to excrete phosphate in the urine in these patients.


Asunto(s)
Fallo Renal Crónico/terapia , Riñón/metabolismo , Fosfatos/metabolismo , Diálisis Renal , Anciano , Biomarcadores/sangre , Nitrógeno de la Urea Sanguínea , Creatinina/sangre , Estudios Transversales , Femenino , Factor-23 de Crecimiento de Fibroblastos , Factores de Crecimiento de Fibroblastos/sangre , Tasa de Filtración Glomerular , Homeostasis , Humanos , Riñón/fisiopatología , Fallo Renal Crónico/sangre , Fallo Renal Crónico/fisiopatología , Fallo Renal Crónico/orina , Masculino , Persona de Mediana Edad , Modelos Biológicos , Hormona Paratiroidea/sangre , Fosfatos/sangre , Fosfatos/orina , Estudios Retrospectivos , Factores de Tiempo
15.
Intern Med ; 50(1): 23-9, 2011.
Artículo en Inglés | MEDLINE | ID: mdl-21212569

RESUMEN

BACKGROUND: Glycated albumin (GA), which is an alternative glycemic marker, is influenced by factors associated with albumin turnover, and it is not clear whether proteinuria influences GA values in diabetic patients with chronic kidney disease (CKD). METHODS: We enrolled 94 diabetic patients with CKD stages 3 to 5. GA, glycated hemoglobin, and urinary protein excretion (UP) levels were consecutively obtained in each patient. The correlations between GA and UP and those between changes in GA and UP were examined. RESULTS: There was a significant correlation between GA and UP in all cases (r=-0.46, p<0.0001), however no significant correlation was found in cases with UP of 0-3.49 g/day (r=0.01). GA values in cases with UP ≥3.5 g/day were significantly lower than those in cases with UP <3.5 g/day [UP ≥3.5 g/day and serum albumin (Alb) ≤3 g/dL; 12.0 ± 1.3%, UP ≥3.5 g/day and Alb >3 g/dL; 17.8 ± 4.3%, 0≥ UP <3.5 g/day; 21.2 ± 4.2%], while no significant difference in HbA(1c) or glucose levels was found. In cases with a minimum of UP ≥0.5 g/day, no significant correlation was found between the difference in GA and the difference in UP at the point of maximum UP and minimum UP (r=0.04). CONCLUSION: Nephrotic-range proteinuria decreases GA values independent of the glycemic state, while non-nephrotic range proteinuria has no significant influence on GA values in diabetic CKD patients.


Asunto(s)
Diabetes Mellitus Tipo 2/sangre , Nefropatías Diabéticas/sangre , Proteinuria/sangre , Insuficiencia Renal Crónica/sangre , Albúmina Sérica/metabolismo , Adulto , Anciano , Biomarcadores/sangre , Estudios Transversales , Diabetes Mellitus Tipo 2/complicaciones , Diabetes Mellitus Tipo 2/orina , Nefropatías Diabéticas/complicaciones , Nefropatías Diabéticas/orina , Femenino , Hemoglobina Glucada/metabolismo , Productos Finales de Glicación Avanzada , Humanos , Fallo Renal Crónico/sangre , Fallo Renal Crónico/complicaciones , Fallo Renal Crónico/orina , Masculino , Persona de Mediana Edad , Síndrome Nefrótico/sangre , Síndrome Nefrótico/complicaciones , Síndrome Nefrótico/orina , Proteinuria/complicaciones , Proteinuria/orina , Insuficiencia Renal Crónica/complicaciones , Insuficiencia Renal Crónica/orina , Albúmina Sérica Glicada
16.
Nephrology (Carlton) ; 16(3): 319-25, 2011 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-21077987

RESUMEN

AIM: Chronic nephrotoxicity of long-term cyclosporine A (CsA) treatment is a matter of concern in patients with steroid-dependent nephrotic syndrome (SDNS). METHODS: Twenty-eight adult NS patients (25, minimal-change nephrotic syndrome (NS); three, focal-segmental glomerulosclerosis) were divided into three groups. Group A was continuously treated with CsA for more than 5 years (143 ± 40 months, 1.3 ± 0.4 mg/kg per day at final analysis, n = 12); group B had been previously treated with CsA (70 ± 27 months, n = 6); and group C had been treated with corticosteroids alone (n = 10). The clinical variables related to chronic CsA nephrotoxicity were examined. RESULTS: In groups A and B, estimated glomerular filtration rate decreased from 86 ± 22 and 107 ± 17 to 83 ± 23 and 88 ± 13 mL/min per 1.73 m(2) , respectively, at final analysis (both P < 0.05). Serum magnesium levels in group A were significantly lower than those in group B or C (A, 1.78 ± 0.16 mg/dL; B, 2.00 ± 0.14 mg/dL; C, 2.03 ± 0.10 mg/dL; A vs B, C, P < 0.01), and a significant correlation between these and the duration of CsA treatment was found (r = -0.68, P < 0.001). There was a trend towards a correlation between the duration of CsA administration and urinary α1-microglobulin (r = 0.38, P = 0.07). CONCLUSION: Mild decrease in renal function and hypomagnesemia were found in adult SDNS patients with long-term CsA treatment. Careful monitoring of renal function, blood pressure and serum magnesium levels is necessary.


Asunto(s)
Corticoesteroides/administración & dosificación , Ciclosporina/efectos adversos , Glomeruloesclerosis Focal y Segmentaria/tratamiento farmacológico , Riñón/efectos de los fármacos , Síndrome Nefrótico/tratamiento farmacológico , Adolescente , Adulto , Anciano , Análisis de Varianza , Biomarcadores/sangre , Presión Sanguínea/efectos de los fármacos , Ciclosporina/administración & dosificación , Esquema de Medicación , Femenino , Tasa de Filtración Glomerular/efectos de los fármacos , Glomeruloesclerosis Focal y Segmentaria/sangre , Glomeruloesclerosis Focal y Segmentaria/fisiopatología , Humanos , Japón , Riñón/metabolismo , Riñón/fisiopatología , Magnesio/sangre , Masculino , Persona de Mediana Edad , Síndrome Nefrótico/sangre , Síndrome Nefrótico/fisiopatología , Recurrencia , Factores de Tiempo , Resultado del Tratamiento , Adulto Joven
17.
Nephrology (Carlton) ; 16(5): 476-82, 2011 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-21126287

RESUMEN

AIM: Haemodiafiltration (HDF) is the most efficient blood purification method and can remove a wide spectrum of solutes of different molecular weights (MW). The purpose of this study was to investigate whether the removed amounts of solutes, especially the larger molecules, could be increased by changing the HDF filtration procedure. METHODS: A new first-half intensive HDF treatment (F-HDF) was designed, whereby convective clearance is intensively forced during the first half of a HDF session. We compared the removed amounts of solutes in the same group of nine patients treated by F-HDF, constant rate-replacing HDF (C-HDF) and a high-flux haemodialysis (HD). RESULTS: F-HDF can remove significantly larger amounts of α(1) -microglobulin (MG), molecular weight (MW) 33,000, compared with HD and C-HDF (30.1 ± 15.1 vs 12.4 ± 0.3, 15.0 ± 3.1 mg, P < 0.01). Regarding the removal amounts and clear space of ß(2) MG, MW 11,800, there were no significant differences between the three treatment modalities. Regarding amounts of creatinine, urea nitrogen and phosphorus, there were no significant differences between the three treatment modalities. CONCLUSION: In post-replacement HDF with a high-flux membrane dialyzer, the method used in the present study in which replacement is completed during the first half of the process, is associated with a greater rate of larger molecule removal than the conventional uniform replacement method.


Asunto(s)
Hemodiafiltración/métodos , Uremia/terapia , Adulto , Anciano , Nitrógeno de la Urea Sanguínea , Creatinina/aislamiento & purificación , Femenino , Humanos , Masculino , Persona de Mediana Edad , Fosfatos/aislamiento & purificación , Uremia/sangre , Microglobulina beta-2/aislamiento & purificación
18.
Hypertens Res ; 32(12): 1123-9, 2009 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-19816503

RESUMEN

The influence of home blood pressure (HBP) control on renal and cardiovascular outcomes is not fully defined, and the optimal blood pressure (BP) target in elderly patients with chronic kidney disease (CKD) remains unknown. To clarify the influence of HBP on the progression of CKD and the occurrence of cardiovascular events in elderly CKD patients, we recruited 104 patients with stage 3 to 5 CKD, who were > or =70 years of age. The mean follow-up duration was 39+/-15 months. HBP was measured every morning and evening for 7 consecutive days. HBP data were obtained every 6 months for 79 of these patients. There were significant correlations observed between morning systolic BP (SBP), evening SBP and the change in estimated glomerular filtration rate (eGFR) during the follow-up period (baseline/follow-up; morning r=-0.55/-0.51, evening r=-0.48/-0.38, all P<0.0001, baseline: baseline values, follow-up: mean values obtained every 6 months during the follow-up period). Stepwise multivariate regression analysis identified morning SBP and urinary protein excretion as independent predictors of a change in eGFR during the follow-up period. Cox proportional hazards analysis showed that baseline morning SBP, baseline evening SBP and follow-up morning SBP were significantly associated with an increased risk of renal events (hazard ratios; 1.04 (95% CI, 1.01-1.07), 1.06 (1.02-1.09) and 1.10 (1.04-1.17), respectively). However, Cox proportional hazards analyses showed that there was no significant association between BP and the risk of cardiovascular events. In conclusion, even among elderly CKD patients, HBP is a significant predictor of decline in renal function and the development of end-stage renal disease. In addition, the optimal target BP for elderly CKD patients needs to be clarified.


Asunto(s)
Monitoreo Ambulatorio de la Presión Arterial , Presión Sanguínea , Hipertensión/diagnóstico , Hipertensión/epidemiología , Insuficiencia Renal Crónica/epidemiología , Anciano , Anciano de 80 o más Años , Antihipertensivos/uso terapéutico , Femenino , Estudios de Seguimiento , Tasa de Filtración Glomerular , Humanos , Hipertensión/tratamiento farmacológico , Japón/epidemiología , Masculino , Análisis Multivariante , Valor Predictivo de las Pruebas , Pronóstico , Modelos de Riesgos Proporcionales , Proteinuria/epidemiología , Factores de Riesgo
19.
Nihon Jinzo Gakkai Shi ; 50(5): 588-96, 2008.
Artículo en Japonés | MEDLINE | ID: mdl-18767487

RESUMEN

PURPOSE: We examined the characteristics of the day-by-day variability of home blood pressure (HBP) in patients with chronic kidney disease (CKD). METHODS: We obtained HBP recordings from 368 CKD patients (63+/-13 years, eGFR 34+/-23 mL/min/1.73 m2, males 253). The day-by-day variability of HBP was defined as the coefficient of variation (CV) values of BP measurements every morning after waking and every evening before sleeping on 7 consecutive days. In a portion of the patients, the CV values of HBP were collected every 6 months during a 2-year period and the association with a decline in GFR was examined. RESULTS: CV values of morning/evening systolic BP (SBP) were 5.4+/-2.4%, 6.1+/-2.9 % (p<0.01). The CV values of morning SBP in females or patients with diabetic nephropathy (DN) were significantly greater than those in males or patients without DN, respectively (females 5.9+/-2.3%, males 5.2+/-2.4%, p< 0.01, DN 6.1+/-2.8 %, non DN 5.2+/-2.2 %, p<0.05). Multivariate linear regression analysis showed that female gender, DN, the number of antihypertensive drugs, higher heart rate and higher CV values of heart rate were associated with higher CV values of the morning SBP. CV values of the morning SBP showed no significant change during the 2-year period (0; 5.4+/-2.6%, 1 year; 5.3+/-2.9%, 2 years 5.6+/-3.1%, n=200). There was no significant difference in the change in eGFR between a group with high CV values (greater than 5 %) and a group with low CV values (lower than 5 %) during the 2-year period. CONCLUSIONS: In CKD patients, the day-by-day variability of HBP tended to be greater in the evening, in female and DN patients. There was no significant association between the day-by-day variability of HBP and decline rate in eGFR. Further studies are needed to clarify the clinical significance of the day-by-day variability of HBP in CKD patients.


Asunto(s)
Monitoreo Ambulatorio de la Presión Arterial , Presión Sanguínea , Ritmo Circadiano/fisiología , Enfermedades Renales/fisiopatología , Adulto , Anciano , Anciano de 80 o más Años , Enfermedad Crónica , Femenino , Humanos , Masculino , Persona de Mediana Edad , Análisis Multivariante
20.
Contrib Nephrol ; 155: 18-28, 2007.
Artículo en Inglés | MEDLINE | ID: mdl-17369710

RESUMEN

BACKGROUND: Evaluation and monitoring of nutritional status is a fundamental concept in providing nutritional care to patients with end-stage renal failure. There have been, however, few practically available indices assessing whole body protein stores of patients. METHODS: We enrolled 448 end-stage renal disease patients, 394 on maintenance hemodialysis (HD) and 54 on continuous ambulatory peritoneal dialysis (PD) in this study. 83 Age- and sex-matched subjects (controls) whose creatinine clearance was more than 70 ml/min and urinary protein excretion was less than 1.0 g/day were also recruited for comparison. To assess whole body somatic protein stores, we devised the body protein index (BPI). The volume of body protein mass was measured by multifrequency bioelectrical impedance analysis and then BPI was calculated as body protein mass (kg) divided by height in meters (m2). Based on BPI, we defined the nutritional status of the patients as normal if the value was within -10% of the mean value of control subjects, -10 to -14% as mild malnutrition, -15 to -19% as moderate malnutrition, and <-20% as severe malnutrition. RESULTS: The required time for measurement was 5.2 +/- 1.3 min and coefficient of variation of measurements was 0.8 +/- 0.2%. Among men the mean BPI in both HD and PD patients was significantly lower than those of control subjects (4.25 +/- 0.37, 4.38 +/- 0.34 vs. 4.72 +/- 0.37 kg/m2, p < 0.001). In women, BPI was significantly lower in HD patients than in control subjects (3.65 +/- 0.34 vs. 4.00 +/- 0.34 kg/m2, p < 0.033), whereas only a nonsignificant lower tendency was found in PD patients (3.83 +/- 0.39 kg/m2, p = 0.067). There were no significant differences in BPI values between diabetic and non-diabetic subjects, both in men (4.26 +/- 0.41 vs. 4.25 +/- 0.36 kg/m2) and women (3.69 +/- 0.36 vs. 3.65 +/- 0.34 kg/m2). Based on BPI nutritional categories, 113 (28.7%) of all HD patients were classified as having mild malnutrition, 57 (14.5%) as having moderate malnutrition, 40 (10.1%) as having severe malnutrition, and 184 (46.7%) were classified as normal. The patients of longer dialysis history groups showed a tendency of lower BPI compared to those of shorter dialysis history groups (p < 0.05), although the ages of the patients of the two groups did not significantly differ. No correlations were found between BPI and serum albumin or transferrin concentrations. Only weak correlations were found with albumin in male and transferrin in female HD patients. CONCLUSION: BPI calculated from measurement of multifrequency bioelectrical impedance analysis could evaluate whole body somatic protein stores, and is a potentially useful new marker assessing nutritional status in patients with chronic renal failure. Decreased body somatic protein stores, mainly due to muscle wasting, was prevalent in end-stage renal failure patients on maintenance dialysis.


Asunto(s)
Composición Corporal/fisiología , Impedancia Eléctrica , Fallo Renal Crónico/fisiopatología , Evaluación Nutricional , Estado Nutricional/fisiología , Diálisis Renal , Adulto , Anciano , Biomarcadores/metabolismo , Femenino , Humanos , Fallo Renal Crónico/complicaciones , Fallo Renal Crónico/terapia , Masculino , Persona de Mediana Edad , Desnutrición Proteico-Calórica/diagnóstico , Desnutrición Proteico-Calórica/etiología , Desnutrición Proteico-Calórica/fisiopatología , Albúmina Sérica/metabolismo , Caracteres Sexuales , Transferrina/metabolismo
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