RESUMEN
In this work, the experimental evidence of glass-like phonon dynamics and thermal conductivity in a nanocomposite made of GeTe and amorphous carbon is reported, which is of interest for microelectronics, and specifically phase change memories. It is shown that, the total thermal conductivity is reduced by a factor of three at room temperature with respect to pure GeTe, due to the reduction of both electronic and phononic contributions. This latter, similarly to glasses, is small and weakly increasing with temperature between 100 and 300 K, indicating a mostly diffusive thermal transport and reaching a value of 0.86(7) Wm-1K-1 at room temperature. A thorough investigation of the nanocomposite's phonon dynamics reveals the appearance of an excess intensity in the low energy vibrational density of states, reminiscent of the Boson peak in glasses. These features can be understood in terms of an enhanced phonon scattering at the interfaces, due to the presence of elastic heterogeneities, at wavelengths in the 2-20 nm range. The findings confirm recent simulation results on crystalline/amorphous nanocomposites and open new perspectives in phonon and thermal engineering through the direct manipulation of elastic heterogeneities.
RESUMEN
The rational design and synthesis of a series of 5-nitro-2-furoic acid analogues are presented. The trypanocidal activity against epimastigote forms of Trypanosoma cruzi and the toxic effects on human HeLa cells were tested. Between all synthetic compounds, three of thirteen had an IC50 value in the range of Nfx, but compound 13 exhibited an improved effect with an IC50 of 1.0 ± 0.1 µM and a selective index of 70 in its toxicity against HeLa cells. We analyzed the activity of compounds 8, 12 and 13 to interfere in the central redox metabolic pathway in trypanosomatids, which is dependent of reduced trypanothione as the major pivotal thiol. The three compounds behaved as better inhibitors of trypanothione reductase than Nfx (Ki values of 118 µM, 61 µM and 68 µM for 8, 12 and 13, respectively, compared with 245 µM for Nfx), all following an uncompetitive enzyme inhibition pattern. Docking analysis predicted a binding of inhibitors to the enzyme-substrate complex with binding energy calculated in-silico that supports such molecular interaction.
Asunto(s)
NADH NADPH Oxidorreductasas/antagonistas & inhibidores , Nitrofuranos/química , Nitrofuranos/farmacología , Tripanocidas/química , Tripanocidas/farmacología , Trypanosoma cruzi/enzimología , Enfermedad de Chagas/tratamiento farmacológico , Enfermedad de Chagas/parasitología , Diseño de Fármacos , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacología , Células HeLa , Humanos , Simulación del Acoplamiento Molecular , NADH NADPH Oxidorreductasas/metabolismo , Trypanosoma cruzi/efectos de los fármacosRESUMEN
We have previously shown that, assuming urea distribution volume (V) remains constant for 1 month, ionic dialysance (ID) allows the dialysis dose to be calculated without the need for blood sampling. The aim of this multicenter study was to verify whether the assumption of a constant V can be extended to 1 year. In clinically stable patients receiving thrice-weekly hemodialysis at 13 dialysis centers, V and Kt/V were assessed during three dialysis sessions at baseline and 1 year later using ID as dialyzer urea clearance and the single-pool urea kinetic model. Baseline albumin, hemoglobin, and C reactive protein were prespecified covariates for predicting the change in V over time. Of the 52 enrolled patients, 40 (25 males; age 63.0+/-13.5 years) completed the study. Baseline end-dialysis body weight (62.4+/-13.7 kg) showed a non-significant 1% reduction during follow-up (-0.6+/-2.8 kg; P=0.175), whereas V significantly decreased from 29.0+/-6.8 to 27.4+/-6.0 l (-1.6+/-3.0 l or 4.5%; P=0.002). The reduction in V was greater when baseline albumin was lower (P=0.001) and baseline V was higher (P=0.005). The single-pool K(t)/V calculated using baseline V underestimated the actual value by 0.07+/-0.16 (P=0.008). The slight underestimate of Kt/V during follow-up suggests that annual V evaluations may be sufficient for dialysis dose quantification as the only risk is underestimating the actually delivered dialysis dose. However, the relationship between baseline albumin and the reduction in V over time may have nutritional value, and suggests more frequent V evaluations.
Asunto(s)
Riñón/fisiología , Diálisis Renal , Urea/orina , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Albuminuria/orina , Peso Corporal , Proteína C-Reactiva/orina , Femenino , Estudios de Seguimiento , Hemoglobinas/análisis , Humanos , Estudios Longitudinales , Masculino , Tasa de Depuración Metabólica , Persona de Mediana Edad , Estado Nutricional , Valor Predictivo de las Pruebas , Estudios Prospectivos , Factores de TiempoRESUMEN
The persistence of a left superior vena cava is the result of a lack of an embryological involution of the left anterior cardinal vein. This anomaly is very rare: about 0.3% of the general population. Its incidence increases remarkably from 3-10% in those patients affected with congenital heart disease. Described herein is a case of persistent left superior vena cava, discovered by chance, following the placement of a central venous catheter for hemodialysis. A chest X-ray in projection back-forward showed the central venous catheter along the left sternal margin simulating a placement in the aorta artery. This clinical picture, as described in the literature, is often accompanied by other anatomical anomalies, in our case, by the congenital agenesis of a solitary pelvic kidney. In agreement with the literature and in contrast with what has been reported recently, we sustain that a central venous catheter placed, for any reason, in the persistent left superior vena cava must be removed immediately because it can induce hyperkinetic arrhythmia and cardiac arrest as in our case. Our case report should be a warning that lack of awareness of the anomalies of the big central veins can cause a rise in morbidity.
RESUMEN
Losartan is the first of a new category of drug that inhibits angiotensin II (ANG II) AT1 receptors antagonists. This drug lowers blood pressure by inhibiting the activity of ANG II and reduces proteinuria and progression of chronic renal failure (CRF). It seems therefore an extremely interesting drug. Aim of this study is to describe 3 cases of acute renal failure (ARF), occurred during therapy with losartan. None of the patients showed renal arteries stenosis or other predisposing factors for the development of ARF. In conclusion, we want pointed out that losartan could affect renal function in a similar way as angiotensin converting enzyme inhibitors (ACEI). We suggested that use of losartan in risk situations, like old age, preexiting CRF, stenosis of renal arteries, solitary kidney and diuretic therapy, should be carefully monitored as well as that of ACE I.
Asunto(s)
Lesión Renal Aguda/inducido químicamente , Antagonistas de Receptores de Angiotensina , Losartán/efectos adversos , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
BACKGROUND: The dual lumen internal jugular venous catheter has proven to be the most useful temporary vascular access for hemodialysis. According to this evidence it was decided to evaluate urea recirculation rate during hemodialysis performed by dual lumen internal jugular catheter (IJC) under normal condition (R1) and when the arterial lumen of the catheter is used as venous lumen, and the venous lumen as arterial lumen (R2). METHODS: In 71 patients who underwent hemodialysis using a dual lumen IJC, urea recirculation rate was measured during a conventional bicarbonate hemodialysis, under normal condition R1 and during the experimental condition R2. RESULTS: Urea recirculation rate < 5% was achieved for almost all patients under normal condition R1. In the different condition R2, urea recirculation rate increased in all patients, from an average value of 3.7 +/- 1.7 to 5.1 +/- 1.8 p < 0.0001. This increment was expected ut surprisingly low. CONCLUSIONS: In conclusion during hemodialysis with dual lumen IJC efficient treatment can be provided in normal condition and also when the venous lumen is used as arterial lumen.
Asunto(s)
Cateterismo Venoso Central/instrumentación , Cateterismo , Diálisis Renal , Lesión Renal Aguda/metabolismo , Lesión Renal Aguda/terapia , Anciano , Arterias , Diseño de Equipo , Estudios de Evaluación como Asunto , Femenino , Soluciones para Hemodiálisis/farmacocinética , Humanos , Venas Yugulares , Masculino , Persona de Mediana Edad , Urea/metabolismo , VenasRESUMEN
The therapeutical approach to arterial hypertension in the general population is now relatively well classified, whereas it remains a controversial problem in dialytic patients. The aim of this study was to evaluate the antihypertensive drugs used in dialytic patients in Piedmont and to identify correlations with other personal and clinical data. The authors analysed the data in the Piedmont Dialysis and Transplant Register concerning new patients admitted to dialysis during the period 1990-1995 (2,664 patients at 31/12/1995) and 1,373 patients who began dialysis during the period 1990-1993. A study of the antihypertensive drugs using in single and combined therapy over the five-year period shows major variations in the 45-65 year-old age bracket (increased ACE-inhibitors in single therapy, 15.5-25.6%, increased vasodilators in combined therapy, 15.3-21%). In patients aged > or = 65 years old a slight increase was found in the use of beta-blockers in monotherapy. Antihypertensive drugs at the 1st control (1990-1995 entries) appeared to be stable over the five-year period. From the 1,373 patients who started dialysis in the period 1990-1993, with at least three subsequent controls, the authors selected those hypertensive or normotensive patients receiving ACE-inhibitor therapy (best survival in general population) and compared their survival with that of patients receiving alternative antihypertensive treatment. No significant differences were found. The stability of the antihypertensive drugs taken by these patients over the past 5 years backs the hypothesis of a greater attention paid by nephrologists to the introduction of new drugs, both because of the frequent onset of collateral effects and owing to the special pharmacokinetics present in dialytic patients.
Asunto(s)
Antihipertensivos , Hipertensión/tratamiento farmacológico , Sistema de Registros/estadística & datos numéricos , Antagonistas Adrenérgicos beta/efectos adversos , Antagonistas Adrenérgicos beta/uso terapéutico , Adulto , Anciano , Inhibidores de la Enzima Convertidora de Angiotensina/efectos adversos , Inhibidores de la Enzima Convertidora de Angiotensina/uso terapéutico , Antihipertensivos/efectos adversos , Antihipertensivos/clasificación , Antihipertensivos/uso terapéutico , Bloqueadores de los Canales de Calcio/efectos adversos , Bloqueadores de los Canales de Calcio/uso terapéutico , Utilización de Medicamentos/tendencias , Femenino , Humanos , Hipertensión/complicaciones , Hipertensión/epidemiología , Italia/epidemiología , Fallo Renal Crónico/complicaciones , Fallo Renal Crónico/mortalidad , Fallo Renal Crónico/fisiopatología , Fallo Renal Crónico/terapia , Masculino , Persona de Mediana Edad , Diálisis Renal , Vasodilatadores/efectos adversos , Vasodilatadores/uso terapéuticoAsunto(s)
Enfermedades Carenciales/diagnóstico , Adulto , Anciano , Antropometría , Avitaminosis/complicaciones , Avitaminosis/diagnóstico , Niño , Enfermedades Carenciales/sangre , Femenino , Humanos , Masculino , Evaluación Nutricional , Trastornos Nutricionales/sangre , Trastornos Nutricionales/diagnóstico , Examen Físico , EmbarazoAsunto(s)
Síndrome de Budd-Chiari/etiología , Quistes/complicaciones , Hepatopatías/complicaciones , Nefrectomía/efectos adversos , Riñón Poliquístico Autosómico Dominante/complicaciones , Síndrome de Budd-Chiari/diagnóstico , Quistes/diagnóstico , Estudios de Seguimiento , Humanos , Trasplante de Riñón , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Riñón Poliquístico Autosómico Dominante/cirugía , RecurrenciaRESUMEN
The high prevalence of HCV positivity in dialysis patients has recently prompted several studies on this controversial subject. The aim of the study was an evaluation of HCV positivity and of influence on clinical outcome in 2,404 patients on dialysis in Piedmont (Northern Italy Region, about 4,400,000 inhab., 20 Dialysis Centers) at December 1993 (32.7% HCV-positive according to the Regional Registry of Dialysis and Transplantation). As expected, a strong correlation was found with time on dialysis (94.4% in patients with treatment follow-up > or = 20 years) and blood transfusions (41.3% HCV positivity in transfused patients versus 22.6% in not transfused ones; p < 0.0001). Dialysis in a hospital setting is confirmed as at high risk of infection, since HCV positivity was 19.6% in patients always treated by bicarbonate dialysis in hospital versus 8.9% in those treated only by CAPD (start of dialysis in 1992-1993). Despite the high prevalence of HCV positivity, however, death rates for liver disease and for all gastrointestinal causes are very low, regardless of HCV antibody status (1.2% in HCV positive versus 2.3% in HCV negative, NS). Whether this depends upon different clinical features of HCV infection in dialysis patients or merely deflects a relatively short follow-up will be matter of discussion in the future.
Asunto(s)
Hepatitis C/epidemiología , Diálisis Renal , Adulto , Causas de Muerte , Estudios de Seguimiento , Hepatitis C/sangre , Anticuerpos contra la Hepatitis C/sangre , Humanos , Italia/epidemiología , Persona de Mediana Edad , Prevalencia , Diálisis Renal/mortalidad , Estudios SeroepidemiológicosRESUMEN
Mismanagement in the placement of central venous catheter (CVC) may occur in up to 20% of cases. The catheter can be inadvertently placed in the contralateral brachiocephalic vein, the ipsi or contralateral internal jugular vein, and usually a thoracic radiograph is necessary to evaluate its location. We propose a technique first described by Serafini et al. to establish the position of a CVC by endocavitary electrocardiography (EC-ECG) and its employment in a large number of uraemic patients requiring haemodialysis. This technique uses the tip of the CVC as reference lead in a standard electrocardiograph. The best employment of this technique has been obtained by echotomographic visualization of the internal jugular vein executed just before transcutaneous puncture of the vessel. For 13 months we have successfully applied this technique in CVC placement in 81 patients requiring haemodialysis. In our opinion this method is a safe and simple technique that avoids the need for thoracic radiographs and time lost waiting for radiographs that prolong the start of the haemodialysis session. According to our experience, we confirm that the EC-ECG technique provides a method for ensuring compliance with Food and Drug Administration guidelines regarding catheter tip location in uraemic patients.
Asunto(s)
Lesión Renal Aguda/terapia , Cateterismo Venoso Central/métodos , Venas Yugulares/diagnóstico por imagen , Diálisis Renal/métodos , Lesión Renal Aguda/diagnóstico por imagen , Lesión Renal Aguda/fisiopatología , Catéteres de Permanencia , Electrocardiografía , Femenino , Humanos , Masculino , Persona de Mediana Edad , UltrasonografíaRESUMEN
Mismanagement in the placement of central venous catheter (CVC) may occur in up to 20% of cases. The catheter can be inadvertently placed in the contralateral brachiocephalic vein, the ipsi or contralateral internal jugular vein, and usually a thoracic radiograph is necessary to evaluate its location. We propose a technique first described by Serafini et al. to establish the position of a CVC by endocavitary electrocardiography (EC-ECG) and its employment in a large number of uraemic patients requiring haemodialysis. This technique uses the tip of the CVC as reference lead in a standard electrocardiograph. The best employment of this technique has been obtained by echotomographic visualization of the internal jugular vein executed just before transcutaneous puncture of the vessel. For 13 months we have successfully applied this technique in CVC placement in 81 patients requiring haemodialysis. In our opinion this method is a safe and simple technique that avoids the need for thoracic radiographs and time lost waiting for radiographs that prolong the start of the haemodialysis session. According to our experience, we confirm that the EC-ECG technique provides a method for ensuring compliance with Food and Drug Administration guidelines regarding catheter tip location in uraemic patients.
Asunto(s)
Cateterismo Venoso Central/métodos , Electrocardiografía/métodos , Diálisis Renal , Lesión Renal Aguda/terapia , Cateterismo Venoso Central/instrumentación , Femenino , Humanos , Venas Yugulares , Masculino , Persona de Mediana EdadAsunto(s)
Síndrome de Budd-Chiari/etiología , Quistes/complicaciones , Hepatopatías/complicaciones , Nefrectomía , Riñón Poliquístico Autosómico Dominante/complicaciones , Complicaciones Posoperatorias , Enfermedad Aguda , Síndrome de Budd-Chiari/diagnóstico , Quistes/diagnóstico , Humanos , Fallo Renal Crónico/cirugía , Trasplante de Riñón , Hepatopatías/diagnóstico , Masculino , Persona de Mediana Edad , Riñón Poliquístico Autosómico Dominante/diagnósticoRESUMEN
We have studied protein metabolism and nutritional status in a group of patients in regular dialysis treatment. In forty-five patients (mean age 58 +/- 11 yr), undergoing maintenance hemodialysis we have measured protein (DPI) ad caloric (CI) intake by a three-day dietary recall. Protein catabolic rate (PCR) using the urea kinetic model (Gotch' variable volume), anthopometric parameters such as weight, height, midarm circumference, skinfold thickness, midarm muscle circumference (AMC), midarm muscle area (AMA), total muscle mass (TMM) and the percentage of body fat were measured as well. PCR was weakly correlated with DPI. TMM showed a direct relationship with DPI and correlated inversely with UNA/NI (Urea Nitrogen Appearance/Nitrogen Intake). 18% of patients were underweight; 17% showed a decrease of AMA. TMM was inversely correlated with total hospitalization days. There were no significant variations of the examined parameters in a year later evaluation. In our experience TMM is the parameter which better correlates with clinical findings.