Elsa Valderrama

Learn More
This paper describes a new tripolar spiral cuff electrode, composed of a thin (10 microm) and flexible polyimide insulating carrier and three circumneural platinum electrodes, suitable for stimulation of peripheral nerves. The cuffs were implanted around the sciatic nerve of two groups of ten rats each, one in which the polyimide ribbon was attached to a(More)
This paper describes the use of a new polyimide sieve electrode as a chronic neural interface to stimulate and record signals from regenerated peripheral nerves. Flexible thin polyimide electrodes were placed in silicone chambers and implanted between the severed ends of the sciatic nerve in rats. The sieve part of the interface has 281 round via holes of(More)
This paper describes some developments, made to obtain a chronic neural interface to record signals from regenerated peripheral nerves. Microperforated silicon dices, fabricated by techniques compatible with CMOS processes, were coupled in silicone nerve chambers and implanted between the severed ends of peripheral nerves in rats. Three configurations of(More)
PURPOSE To assess a new flexible, multicontact spiral-cuff electrode made of polyimide with integrated platinum contacts for selective stimulation of nerve fascicles. METHODS Polyimide cuff electrodes with 12 Pt sites in the spiral cuff were acutely implanted around the sciatic nerve of rats. Stimulation was applied through each one of the four tripoles(More)
Renal tubular acidosis and tetany were the 1st manifestations of Kearns-Sayre syndrome in a 5-year-old child. Subsequently, he developed progressive external ophthalmoplegia, ptosis, retinopathy, heart block, and endocrinopathy. There was a 7.5-kb deletion of mitochondrial DNA documented in muscle, kidney, skin fibroblasts, and leukocytes, providing(More)
BACKGROUND Idiopathic membranous nephropathy (IMN) is one of the most common causes of primary nephrotic syndrome in adults. However, it is a relatively rare entity in the pediatric population and there is a paucity of data about the incidence, prognosis, and optimal treatment of IMN in children and adolescents. We conducted this study to evaluate pediatric(More)
Hyperuricemia is present in 20-40% of pediatric and adult patients with essential hypertension. This metabolic abnormality may represent an additional risk factor for the development of cardiovascular disease. Therefore, we performed the following studies to determine 1) whether hyperuricemia is more prevalent in the spontaneously hypertensive rat (SHR) and(More)
Meningioangiomatosis is a rare condition, probably hamartomatous, characterized by proliferation of capillary-sized vessels, meningothelial cells, and fibroblasts within the cortex of the brain. Lesions may be single or diffuse and may be associated with neurofibromatosis type II. Clinically it presents with seizures but may be asymptomatic throughout life.(More)
BACKGROUND Previous studies have examined the spectrum of diseases identified with a kidney biopsy and the complications of the procedure. However, few studies have examined the utility of the test to clarify the diagnosis and guide treatment of pediatric patients. This retrospective, single-center chart review was performed to test the hypothesis that at(More)
Astroblastoma, a unique glial tumor, has been described in the literature in case reports and small series. Its rarity has prevented evidenced-based treatment stratification. An 8-year-old boy presented with signs and symptoms of raised intracranial pressure. Imaging studies of the brain demonstrated a large heterogeneously enhancing solid mass in the left(More)
  • 1