Bioinspired Multiresonant Acoustic Devices Based on Electrospun Piezoelectric Polymeric Nanofibers.

Cochlear hair cells are critical for the conversion of acoustic into electrical signals and their dysfunction is a primary cause of acquired hearing impairments, which worsen with aging. Piezoelectric materials can reproduce the acoustic-electrical transduction properties of the cochlea and represent promising candidates for future cochlear prostheses. The majority of piezoelectric hearing devices so far developed are based on thin films, which have not managed to simultaneously provide the desired flexibility, high sensitivity, wide frequency selectivity, and biocompatibility. To overcome these issues, we hypothesized that fibrous membranes made up of polymeric piezoelectric biocompatible nanofibers could be employed to mimic the function of the basilar membrane, by selectively vibrating in response to different frequencies of sound and transmitting the resulting electrical impulses to the vestibulocochlear nerve. In this study, poly(vinylidene fluoride-trifluoroethylene) piezoelectric nanofiber-based acoustic circular sensors were designed and fabricated using the electrospinning technique. The performance of the sensors was investigated with particular focus on the identification of the resonance frequencies and acoustic-electrical conversion in fibrous membrane with different size and fiber orientation. The voltage output (1-17 mV) varied in the range of low resonance frequency (100-400 Hz) depending on the diameter of the macroscale sensors and alignment of the fibers. The devices developed can be regarded as a proof-of-concept demonstrating the possibility of using piezoelectric fibers to convert acoustic waves into electrical signals, through possible synergistic effects of piezoelectricity and triboelectricity. The study has paved the way for the development of self-powered nanofibrous implantable auditory sensors.

Telomere attrition with age in a wild amphibian population.

Telomere shortening with age has been documented in many organisms, but few studies have reported telomere length measurements in amphibians, and no information is available for growth after metamorphosis, nor in wild populations. We provide both cross-sectional and longitudinal evidence of net telomere attrition with age in a wild amphibian population of natterjack toads (Epidalea calamita). Based on age-estimation by skeletochronology and qPCR telomere length measurements in the framework of an individual-based monitoring programme, we confirmed telomere attrition in recaptured males. Our results support that toads experience telomere attrition throughout their ontogeny, and that most attrition occurs during the first 1-2 years. We did not find associations between telomere length and inbreeding or body condition. Our results on telomere length dynamics under natural conditions confirm telomere shortening with age in amphibians and provide quantification of wide telomere length variation within and among age-classes in a wild breeding population.

Nonprogrammed Vascular Access Is Associated With Greater Mortality in Patients Who Return to Hemodialysis With a Failing Renal Graft.

BACKGROUND: In incident hemodialysis (HD) patients, the use of catheters is associated with a worse prognosis when compared with those with an arteriovenous fistula, but the role of vascular access (VA) type in the morbidity and mortality of patients returning to HD with a failing renal allograft is unknown. We aimed to determine the associations between the type of VA and mortality in this population. METHODS: This was a retrospective observational cohort study of 138 patients who initiated dialysis after kidney transplant failure between 1995 and 2014. We recorded access type, laboratory values at entry, stratified patients per risk, and determined the effect on mortality of programmed VA (PVA), (arteriovenous fistula or PTFE graft) and nonprogrammed VA (UPVA) (tunneled or nontunneled catheters) at the initiation of HD. RESULTS: Eighty-five (61.6%) and 53 (38.4%) patients initiated therapy with PVA and UPVA, respectively. Overall mortality was 14.6% at 1 year. Patients using catheters had greater mortality than those with a PVA (log rank P <0.0001). At 24 months, 7 patients died in PVA group versus 22 in UPVA group. Multivariate Cox analysis showed that initiation of HD with a catheter (hazard ratio, 5.90; 95%, confidence interval, 2.83-12.31) was independently associated with greater mortality after adjusting for confounders. CONCLUSIONS: Nonprogrammed VA with a catheter predicted all-cause mortality among patients with transplant failure reentering HD.

Travel for transplantation and transplant commercialism in Argentina: a 4-decade experience from a University Hospital.

Travel for transplantation and transplant commercialism have become major issues in the last years, generating a passionate medical, legal, and ethical debate. We evaluated the general characteristics of patients who received a kidney transplant abroad and were subsequently followed in our institution. Then, we carried out a retrospective analysis of travelers' outcomes and compared them with a matched cohort of patients transplanted in our center. Between 1971 and 2008, 58 kidney transplants were performed outside Argentina and were subsequently followed up at our institution. The main destinations were the USA (32.8%), Bolivia (29.3%), and Brazil (17.2%). Deceased donor transplants were the most common (53.4%) followed by unrelated living donors (32.8%). No difference was observed between travelers and controls in terms of one-month and one-yr renal function and one-yr and five-yr graft survival. Travelers had significantly less time on dialysis before transplantation than controls. The major destination among all travelers was the USA, and the main destination for commercial transplants was Bolivia. The destination countries involved in our study and the apparent non-inferiority of travelers graft outcomes differ from those of previous reports.

[Rapidly progressive crescentic glomerulonephritis in the elderly]. / Glomerulonefritis rápidamente progresiva en ancianos.

Rapidly progressive glomerulonephritis (RPGN) is a syndrome characterized by glomerular lesions giving rise to acute renal injury that develops within a brief period of time, usually days or a few months. It is classified according to the underlying mechanism of injury and the immunofluorescence findings into four main disorders. In the last decade, nephrologists have witnessed a steady rise in the mean age of the patients diagnosed with RPGN. This observation may reflect an increase in the incidence of this entity and also a more timely diagnosis. We present 3 cases of RPGN in elderly patients, diagnosed within a 3 month period at our institution which illustrates the spectrum of these conditions.

An experimental evaluation of the influence of water depth and bottom color on the Common kingfisher's foraging performance.

To investigate how depth and bottom color affect prey selectivity in Common kingfisher (Alcedo atthis), we developed several experimental procedures using captive birds. We used 20 young kingfishers to test depth (25 or 50cm) and color (natural gravel or white) effects on foraging behavior. Live freshwater fish were used as target prey. To assess differences resulting from the natural behavior of different fish, we chose bottom-dwelling [Ebro barbel (Barbus graellsii)] and open-water benthopelagic species [Ebro nase (Parachondrostoma miegii) and Pyrenean minnow (Phoxinus bigerri)]. The number of attempts and captures, as well as the effects of hunger and experience, were assessed relative to feeding behavior. The effect of fish behavior, as observed in grouped vs. isolated fish, on the kingfisher's performance was also tested. The results showed a significant effect of depth, with more attacks and greater success in shallow waters. No significant differences in catch success between natural- and white-colored bottoms were observed. Hunger had no effect on fishing success, but experience had a positive effect in shallow waters and on white bottoms. Both bottom- and open-water species were consumed equally. Kingfishers preyed more often upon grouped prey than upon isolated prey, although capture success did not vary between the two cases. Our results suggest that kingfishers prey upon the most accessible types of prey.

Glomerulonefritis rápidamente progresiva en ancianos / Rapidly progressive crescentic glomerulonephritis in the elderly

La glomerulonefritis rápidamente progresiva (GNRP) es un síndrome clínico que se caracteriza por la presencia de signos urinarios de enfermedad glomerular e insuficiencia renal de desarrollo en un lapso de días a pocos meses. La inmunofluorescencia permite clasificar a las GNRP en cuatro tipos según se identifiquen o no depósitos inmunes y, si están presentes, de acuerdo con su naturaleza. En la última década se ha demostrado un aumento constante en el promedio de edad de los pacientes con GNRP. Este fenómeno podría reflejar tanto una mayor incidencia de la enfermedad, como un incremento en la tasa de diagnóstico. Se presentan 3 casos de GNRP en adultos mayores de 65 años, diagnosticados en un periodo de 3 meses en nuestra institución.

Rapidly progressive glomerulonephritis (RPGN) is a syndrome characterized by glomerular lesions giving rise to acute renal injury that develops within a brief period of time, usually days or a few months. It is classified according to the underlying mechanism of injury and the immunofluorescence findings into four main disorders. In the last decade, nephrologists have witnessed a steady rise in the mean age of the patients diagnosed with RPGN. This observation may reflect an increase in the incidence of this entity and also a more timely diagnosis. We present 3 cases of RPGN in elderly patients, diagnosed within a 3-month period at our institution which illustrates the spectrum of these conditions.

Glomerulonefritis rápidamente progresiva en ancianos / Rapidly progressive crescentic glomerulonephritis in the elderly

La glomerulonefritis rápidamente progresiva (GNRP) es un síndrome clínico que se caracteriza por la presencia de signos urinarios de enfermedad glomerular e insuficiencia renal de desarrollo en un lapso de días a pocos meses. La inmunofluorescencia permite clasificar a las GNRP en cuatro tipos según se identifiquen o no depósitos inmunes y, si están presentes, de acuerdo con su naturaleza. En la última década se ha demostrado un aumento constante en el promedio de edad de los pacientes con GNRP. Este fenómeno podría reflejar tanto una mayor incidencia de la enfermedad, como un incremento en la tasa de diagnóstico. Se presentan 3 casos de GNRP en adultos mayores de 65 años, diagnosticados en un periodo de 3 meses en nuestra institución.(AU)

Rapidly progressive glomerulonephritis (RPGN) is a syndrome characterized by glomerular lesions giving rise to acute renal injury that develops within a brief period of time, usually days or a few months. It is classified according to the underlying mechanism of injury and the immunofluorescence findings into four main disorders. In the last decade, nephrologists have witnessed a steady rise in the mean age of the patients diagnosed with RPGN. This observation may reflect an increase in the incidence of this entity and also a more timely diagnosis. We present 3 cases of RPGN in elderly patients, diagnosed within a 3-month period at our institution which illustrates the spectrum of these conditions.(AU)

Glomerulonefritis rápidamente progresiva en ancianos. / [Rapidly progressive crescentic glomerulonephritis in the elderly].

Rapidly progressive glomerulonephritis (RPGN) is a syndrome characterized by glomerular lesions giving rise to acute renal injury that develops within a brief period of time, usually days or a few months. It is classified according to the underlying mechanism of injury and the immunofluorescence findings into four main disorders. In the last decade, nephrologists have witnessed a steady rise in the mean age of the patients diagnosed with RPGN. This observation may reflect an increase in the incidence of this entity and also a more timely diagnosis. We present 3 cases of RPGN in elderly patients, diagnosed within a 3 month period at our institution which illustrates the spectrum of these conditions.

Inductive and ultrasonic multi-tier interface for low-power, deeply implantable medical devices.

We report the development of a novel multi-tier interface which enables the wireless, noninvasive transfer of sufficient amounts of power as well as the collection and transmission of data from low-power, deeply implantable analog sensors. The interface consists of an inductive coupling subsystem and an ultrasonic subsystem. The designed and experimentally verified inductive subsystem ensures that 5 W of power is transferred across 10 mm of air gap between a single pair of PCB spiral coils with an efficiency of 83% using our prototype CMOS logic gate-based driver circuit. The implemented ultrasonic subsystem, based on ultrasonic PZT ceramic discs driven in their low-frequency, radial/planar-excitation mode, further ensures that 29 µW of power is delivered 70 mm deeper inside a homogenous liquid environment-with no acoustic matching layer employed-with an efficiency of 1%. Overall system power consumption is 2.3 W. The implant is intermittently powered every 800 msec; charging a capacitor which provides sufficient power for a duration of ~ 18 msec; sufficient for an implant µC operating at a frequency of 500 KHz to transmit a nibble (4 bits) of digitized sensed data.

[Tumor lysis syndrome in a patient with a renal carcinoma treated with sunitinib]. / Síndrome de lisis tumoral en un paciente con cáncer de riñón tratado con sunitinib.

The tumor lysis syndrome (TLS) is a metabolic disorder resulting from a massive tumor breakdown. It is characterized by hyperuricemia, hyperphosphatemia, hypocalcemia and hyperkalemia and predisposes to acute renal failure. TLS usually occurs after the initiation of cytotoxic therapy and is more frequent in the case of neoplasias with a high proliferative rate or that are highly chemo-sensitive. We report the case of a man with a recurrent kidney cancer who presented with a TLS and acute renal failure after initiation of sunitinib.

Síndrome de lisis tumoral en un paciente con cáncer de riñón tratado con sunitinib / Tumor lysis syndrome in a patient with a renal carcinoma treated with sunitinib

El síndrome de lisis tumoral (SLT) es un trastorno metabólico que ocurre como consecuencia de una destrucción celular masiva. Se caracteriza por la presencia de hiperuricemia, hiperfosfatemia, hipocalcemia e hiperkalemia, y predispone al desarrollo de insuficiencia renal aguda. En la mayoría de los casos el SLT ocurre luego de instaurarse un tratamiento antitumoral y es más frecuente en tumores de alto grado de malignidad y alta sensibilidad a la quimioterapia. Presentamos el caso de un paciente con diagnóstico de cáncer de riñón recidivado que presenta un SLT e insuficiencia renal aguda luego de iniciar tratamiento con sunitinib.

The tumor mor lysis syndrome (TLS) is a metabolic disorder resulting from a massive tumor breakdown. It is characterized by hyperuricemia, hyperphosphatemia, hypocalcemia and hyperkalemia and predisposes to acute renal failure. TLS usually occurs after the initiation of cytotoxic therapy and is more frequent in the case of neoplasias with a high proliferative rate or that are highly chemo-sensitive. We report the case of a man with a recurrent kidney cancer who presented with a TLS and acute renal failure after initiation of sunitinib.

Short and long term outcome of kidney transplanted patients with chronic viral hepatitis B and C.

INTRODUCTION: Liver disease related to chronic viral hepatitis is a major cause of morbidity and mortality in renal transplant patients. There is no agreement upon the influence of chronic hepatitis B (HBV) and hepatitis C (HCV) infection in patient and graft survival. AIMS: The aim of the study was to evaluate the influence of HBV and HCV on patient and graft short and long term survival, in the patients transplanted at our institution. MATERIALS AND METHODS: We evaluated the influence of antiHCV and HBsAg status (positive vs. negative); sex; age (> 49 years vs. < 49 years at transplantation); time on dialysis (> 3 vs. < 3 years); acute rejection; kind of graft (deceased vs. living donor, and kidney versus kidney and pancreas); number of transplantations; use of induction immunosuppression; and maintenance immunosuppression treatment (comparing the traditional triple therapy containing azathioprine, cyclosporine and prednisone vs. newer regimens which include tacrolimus, mycophenolate mofetil, sirolimus, etc) on the survival, long term and within the first month of transplantation, of the graft and the patients transplanted in our Institution between January 1991 and August 2009. RESULTS: We included 542 patients, 60% males. median age of 42.03 years (SD 13.06 years). 180 patients (33%) were antiHCV positive and 23 (4%) were HBsAg positive. AntiHCV positive, traditional triple therapy and acute rejection were associated with diminished graft survival. Older age, antiHCV positive, HBsAg positive, deceased donor, kidney-pancreas transplantation and traditional triple therapy were associated with diminished patient survival. Traditional triple therapy was associated with diminished one month graft survival; and older age and antiHCV positive were associated with diminished one month patient survival. CONCLUSION: In our experience, antiHCV positive status was associated with diminished long term patient and graft survival, and diminished six month graft survival; and HBsAg positive was associated with diminished patient survival.

Identification of hepatitis C virus RNA in peritoneal dialysis fluid of patients with viremia.

BACKGROUND: The potential risk for transmission of hepatitis C virus (HCV) by peritoneal dialysis (PD) has been studied previously, with conflicting results. METHODS: To assess whether HCV crosses the peritoneal membrane, the following determinations were performed in 16 patients (7 males, 9 females; mean age 41.8 years; mean time on PD 14 +/- 15 months) undergoing PD: serum anti-HCV using second-generation enzyme-linked immunosorbent assay (ELISA), serum and PD fluid HCV RNA by nested polymerase chain reaction, HCV genotyping by restriction fragment length polymorphism, and serum HCV load by branched DNA assay. RESULTS: Anti-HCV was positive in 10 patients. Serum HCV RNA was positive in 7 anti-HCV-positive patients and negative in all anti-HCV-negative patients. Fluid HCV RNA was detected in 5 (71.4%) patients testing positive for serum HCV RNA and in none testing negative for serum HCV RNA. Serum HCV genotype was 1a in 3 patients and 1b in 4; PD fluid HCV genotype was 1a in 1 patient and 1b in 4. Genotypes in serum and fluid were concordant when both were positive. Serum viral load ranged from nondetectable by the quantitative method to 5.1 MEq genome/mL in patients with fluid infection, and 1.05 MEq and 29 MEq genome/mL in the remaining 2 patients without detectable HCV in PD fLuid. CONCLUSIONS: HCV crosses the peritoneal membrane and may be detected in the dialysate of PD patients with proven viremia. Although our study population was small for firm conclusions to be drawn, this passage does not seem to depend upon the serum viral load. Our data support the notion that PD fluid needs careful handling and local disinfection to prevent possible spreading of viruses, in the institutional and the domestic environments.

HBsAg as predictor of outcome in renal transplant patients.

Chronic liver infections related to hepatitis B and C viruses are a common problem in renal transplant patients with a prevalence of 1.5 to 50% in different countries. There is no uniform agreement regarding their influence on the incidence of acute rejection, graft outcome and survival of renal transplant patients. We retrospectively evaluated the influence of antiHBc, antiHCV and HBsAg positive status; gender; age over 50 years of age at the time of transplantation; pre and postransplantation alaninaminotransferase (ALT) elevation; acute rejection; type of graft; number of transplants; and maintenance and induction immunosuppression treatment on the incidence of acute rejection and both graft and patient survival in the population transplanted in our center between 1991 and 1998. The univariate analysis showed that antiHCV, HBsAg and antiHBc status, more than one renal transplant and one or more episodes of acute rejection were associated with diminished graft survival; and being over the age of 50 at the time of transplantation was also associated with diminished patient survival. In the multivariate analysis HBsAg positive and one or more episodes of rejection were associated with a diminished graft survival, and none of the variables studied was associated with diminished patient survival. In conclusion antiHCV and HBsAg positive status was associated with an increased risk of losing the transplanted kidney, and HBsAg positivity was associated with an increased risk of death, but this was not a statistically significant association.

[High doses of aspirin reduce natriuresis in hypertensive patients treated with enalapril]. / Dosis elevadas de aspirina disminuyen la natriuresis en hipertensos tratados con enalapril.

Angiotensin converting enzyme inhibitors have been shown to be useful in the treatment of essential hypertension while anti-platelet agents improve the overall cardiovascular risk profile in this population. Our aim was to assess the interaction of two different aspirin (ASA) doses--81 and 325 mg/day--with the antihypertensive effect of enalapril as well as their impact upon the urinary sodium excretion (Na(u)). A total of 22 patients between 35 and 65 years of age were included in a prospective double blind trial with a partial cross-over design. We excluded patients with secondary hypertension and recent use of anti-inflammatory drugs. Patients were placed on enalapril and a low sodium diet--<6 g of NaCl/day--and, sequentially, on two different doses of aspirin separated by a 10 day wash out period. Blood pressure (BP) was measured at weekly visits. Systolic, diastolic and mean BP levels decreased significantly in enalapril-treated patients (p<0.01) and no difference was detected between the two AAS dosages although a non-statistically significant difference towards better BP control was observed when 81 mg of ASA was used. Na(u) was higher at baseline when compared with the two periods under ASA (p<0.01) and Na(u) was higher with 81 mg than with 325 mg. These results suggest that in essential hypertensive individuals treated with enalapril and two ASA doses, low doses of ASA are associated with better blood pressure control and higher natriuresis.

[First degree atrio-ventricular block in acute thyrotoxicosis]. / Bloqueo aurículo-ventricular de primer grado en tirotoxicosis aguda.

Thyrotoxicosis may present with a variety of cardiovascular symptoms. Sinus tachycardia is the most frequently encountered electrocardiographic abnormality and conduction disturbances are extremely uncommon. We present a case of first degree atrio-ventricular block in a patient with newly diagnosed hyperthyroidism and discuss the underlying pathophysiological mechanisms and the clinical implications from the internist's standpoint.

[Membranous kidney diseases in adults]. / La nefropatía membranosa del adulto.

Membranous nephropathy is the most common histologic phenotype associated with the primary nephrotic syndrome in adults and the second most common etiological diagnosis in over sixteen hundred renal biopsies on native kidneys processed at our institution over a 30 year period. Renal survival at 10 years is about 70%, but the course of the disease is related to a series of factors which have constituted the basis for mathematical models developed to predict the natural history in a given individual. These factors are gender, age, renal function at the time of diagnosis, presence of the nephrotic syndrome, high blood pressure and the degree of structural damage. Although in low risk patients a period of observation and the use of ACE inhibitors is a reasonable option, most nephrologists would elect to use pharmacological treatment to induce remissions of proteinuria and preserve renal function. The use of steroids and cytotoxic agents in alternating monthly cycles over six months is firmly supported by controlled, randomized clinical trials. If patients are resistant to this regimen or clinical considerations indicate it may be inappropriately toxic, the use of cyclosporin over 6 to 12 months is also a good choice, and it has been shown to be useful even in the context of deteriorating renal function. Mycophenolate mofetil and possibly rituximab may be options of last resort before considering the patient resistant to therapy. At all times, treatment of hypertension, non-specific antiproteinuric measures, and preventing complications of the nephrotic state should be top priorities in the overall therapeutic strategy.

Dosis elevadas de aspirina disminuyen la natriuresis en hipertensos tratados con enalapril / High doses of aspirin reduce natriuresis in hypertensive patients treated with enalapril

Los inhibidores de la enzima convertidora de la angiotensina (IECA) han demostrado ser eficases en el tratamiento de la hipertensión arterial. Sin embargo, una importante proporción de hipertensos recibe además antiagregación plaquetaria con ácido acetil salicílico (AAS), y la consecuente inhibición de la síntesis de prostaglandinas con AAS atenuaría el efecto vasodilatador y la mayor excreción urinaria de sodio (Na(u)) atribuidas al IECA. Nuestro objetivo fue evaluar la interacción de dos dosis de AAS (81 y 325 mg/día) sobre el efecto hipotensor del enalapril y el impacto sobre la excreción de (Na(u)) en pacientes hipertensos. Se incluyeron 22 pacientes de ambos os sexos, entre 35 y 65 años. Todos reciberon enalapril, dieta hiposódica y, secuencialmente separadas por período de (wash out), las dos dois de AAS durante los setenta días del estudio. Se evaluó: presdión arterial sistólica (PAS), diastólica (PAD), media (PAM) y (Na(u)) en un período basal (PB), con 325 y 81 mg de AAS (P1 y P2 respectivamente). Comparando el PB con P1 y P2, se observó una reduccíon significativa de la PAS, PAD, PAM (p<0.01). Al comparar la PAS, PAD, PAM entre P1 y P2, no hubo diferencias significativas. La (Na(u)) en el PB fue mayor (p<0.01)con respecto al P1 y P2, y también P2 con respecto a P1. Estos resultados sugieren que en una población de pacientes hipertensos esenciales tratados con elapril y diferentes dosis de AAS, el tratamiento con dosis bajas de AAS está asociado a mejor control de la PA y mayor eliminación de sodio urinario.