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Biomedical subjects

Marcela Vergara

Publications and source records attributed to Marcela Vergara.

12 recordsLinked to original sources
PubMed2005

Efficacy of mycophenolate mofetil in pediatric patients with steroid-dependent nephrotic syndrome.

Most patients with minimal change nephrotic syndrome are steroid responsive and tolerate this medication. However, a substantial number of patients relapse frequently and become steroid dependent. These patients often require treatment with alternative immunosuppressive drugs to maintain remission and minimize steroid toxicity. Previous studies have suggested that mycophenolate mofetil is effective in treating these patients. However, there are limited data on the effectiveness of this agent in pediatric patients, specifically those with steroid-dependent nephrotic syndrome. The purpose of this study was to assess the efficacy and safety of mycophenolate mofetil therapy in children and adolescents with steroid-dependent nephrotic syndrome who failed other treatments. A retrospective chart review was performed on all patients with steroid-dependent nephrotic syndrome. Clinical characteristics, laboratory data and the relapse rate were assessed prior to and during mycophenolate mofetil treatment. Twenty-one patients, ages 2-17 years, with steroid-dependent nephrotic syndrome who were treated with mycophenolate mofetil between 2001-2005 were included in this review. The indication for mycophenolate mofetil use was steroid dependence in 17 and steroid toxicity in 4 patients. The mean duration of treatment was 1.0+/-0.5 years (range: 0.2-2.0 years). Patients treated with mycophenolate mofetil had a reduction in relapse rate from 0.80+/-0.41 to 0.47+/-0.43 relapses per month ( P <0.02). Side effects were mild and mostly gastrointestinal in nature. In 1 child, mycophenolate mofetil was discontinued due to varicella infection and not restarted. The findings indicate that mycophenolate mofetil is a useful adjunctive therapy in the treatment of patients with steroid-dependent nephrotic syndrome. It lowers the relapse rate by 40% and is well tolerated by patients with steroid-dependent nephrotic syndrome.

Adolescent↗
PubMed2004

Cardiac disease in children with primary glomerular disorders-role of focal segmental glomerulosclerosis.

Anecdotal reports suggest a higher frequency of serious cardiac complications, particularly cardiomyopathy and congestive heart failure (CHF), in children with focal segmental glomerulosclerosis (FSGS). We report the occurrence of cardiac disease in children with FSGS compared with other glomerular causes of primary nephrotic syndrome (NS). A chart review was performed on all patients evaluated at the Schneider Children's Hospital between 1985 and 2003 with a diagnosis of membranoproliferative glomerulonephritis (MPGN), membranous nephropathy (MN), focal global glomerulosclerosis (FGGS), and FSGS. Clinical and demographic data were compiled, specifically whether or not the patient had clinically evident cardiac disease. The blood pressure (BP) and hematocrit in patients with FSGS and chronic renal failure (CRF) (glomerular filtration rate <30 ml/min per 1.73 m(2)) in the 3 months prior to the development of cardiac complications were compared with the values in FSGS patients with CRF but no cardiac complications, and in patients with the other causes of primary NS in whom CRF developed. There were 48 patients with FSGS, 22 with MPGN, 19 with MN, and 4 with FGGS. Cardiac disease occurred in 6 children (mean age 11 years), all with FSGS. Four of these patients were black and 5 were female. CHF occurred in all patients, cardiomyopathy in 4, and left ventricular hypertrophy in 5 patients. There was no significant difference in the BP and the hematocrit levels between the 6 patients with both FSGS and cardiac disease, 3 patients with FSGS and CRF but no cardiac disease, and the 5 patients with the other glomerulopathies in whom CRF occurred ( P>0.1). Our findings suggest that there is a clinical association between FSGS and cardiac disease in pediatric patients. We speculate that the immune mechanism responsible for the development of FSGS may also affect the heart.

Child↗
PubMed2004

Diagnostic yield of parathyroid hormone testing in children evaluated for hypercalciuria.

Hypercalciuria is a frequent cause of non-glomerular hematuria in pediatric patients. Because hypercalciuria can be secondary to primary hyperparathyroidism, measurement of serum parathyroid hormone (PTH) levels is often performed in children with this urinary abnormality. A retrospective chart review was performed to determine the diagnostic yield of PTH measurements when performed under these clinical circumstances. Over a 30-month period (January 1, 2001 to September 30, 2003), among 31 children who had a PTH determination, the level was elevated in 1 (3%) patient. Based on these findings and the serious nature of untreated primary hyperparathyroidism, serum PTH level should be measured in pediatric patients with newly diagnosed hypercalciuria.

Calcium↗
PubMed2003

Urinary tract infections, VUR, and autosomal dominant polycystic kidney disease.

This case series of 16 patients with autosomal dominant polycystic kidney disease (ADPKD) describes 4 girls who presented with a urinary tract infection (UTI). Radiological evaluation revealed that each of these patients had vesicoureteral reflux (VUR). The frequency of VUR was significantly higher in the patients with ADPKD compared with otherwise healthy age-matched children who underwent testing after a UTI (100% versus 15%, P<0.002). These findings suggest VUR is an associated somatic anomaly in children with ADPKD that may contribute to the occurrence of UTI in this patient population.

Child↗
PubMed2003

Outcome after renal transplantation in children: results of follow-up by nephrologists in a primary referral center.

Pediatric patients who receive a kidney transplant require extended follow-up to monitor graft function and for management of complications. Because of convenience, most patients are sent back to the nephrologists who referred them for transplantation (the primary nephrologist) for long-term care. As a consequence, many pediatric nephrologists who provide this extended care are not associated with a transplant center. It is not known if this arrangement yields satisfactory outcomes for children and adolescents who receive a kidney transplant. The objective was to determine if clinical outcomes are satisfactory in pediatric renal transplant recipients who were followed up by their primary nephrologists after the procedure. A chart review was carried out on all renal transplant recipients seen in the renal clinic at Schneider Children's Hospital (SCH) from 1982 to 2001. Patients were eligible if they were followed up by the primary referring nephrologists at SCH for a minimum of 6 months after transplantation. Relevant demographic and clinical outcome data were compiled. Twenty-eight patients who received a total of 33 renal allografts [living related donors (LRD) 15 and cadaveric donors (CD) 18] were seen during the study period. The transplantations in 19 children (68%) were carried out at Montefiore Hospital (Bronx, NY, USA), while the rest were performed at other centers. There were three (11%) deaths, two LRD patients and one CD patient. The group of 25 surviving patients consisted of 17 males and eight females, age range 4-28 yr (mean 17.2 yr). The mean duration of renal allograft survival was 6.3 +/- 5.3 yr and the mean duration of follow-up was 6.1 +/- 5.3 yr. The most recent serum creatinine ranged from 0.5 to 3.8 mg/dL with a mean of 1.3 +/- 0.8 mg/dL. There were several complications including acute rejection, renal artery stenosis, and hydronephrosis in the allograft. The team of primary referring nephrologists successfully treated all of these except the child with hydronephrosis. The primary nephrologist who refers pediatric patients to a tertiary care transplant center can accomplish long-term follow-up of renal transplant recipients after discharge from the transplant center. The clinical outcomes are acceptable and compare favorably with the results described in the literature that have been achieved in patients followed up at transplant centers. Problems rarely developed that required referral back to the transplant center for management. This approach to care is recommended because it is more likely to foster compliance by both patients and parents.

Adolescent↗
PubMed2003

mt1 Melatonin receptor in the primate adrenal gland: inhibition of adrenocorticotropin-stimulated cortisol production by melatonin.

The pineal hormone melatonin participates in circadian, seasonal, and reproductive physiology. The presence of melatonin binding sites in human brain and peripheral tissues is well documented. However, in the mammalian adrenal gland, low-affinity melatonin binding sites have been detected only in the rat by some but not all authors. Conflicting evidence for a regulatory role of melatonin on adrenal cortisol production, prompted us to investigate this possibility in a New World primate, the capuchin monkey. Expression of melatonin receptors in the adrenal cortex was demonstrated through pharmacological characterization and autoradiographic localization of 2-[125I]iodomelatonin binding sites (dissociation constant = 96.9 +/- 15 pM; maximal binding capacity = 3.8 +/- 0.4 fmol/mg protein). The mt1 identity of these receptors was established by cDNA sequencing. Melatonin treatment of dispersed cells and explants from adrenal gland did not affect basal cortisol production. However, cortisol production stimulated by 100 nM ACTH was significantly inhibited by low melatonin concentrations (0.1-100 nM); this inhibitory effect was reversed by the mt1/MT2 melatonin antagonist luzindole. Melatonin also inhibited dibutyril-cAMP-stimulated cortisol production, suggesting that melatonin acts through a cAMP-independent signaling pathway. The present data demonstrate that the primate adrenal gland cortex expresses functional mt1 melatonin receptors and shows that melatonin inhibits ACTH-stimulated cortisol production.

Adrenal Glands↗
PubMed2003

Evaluation of failure to thrive: diagnostic yield of testing for renal tubular acidosis.

BACKGROUND: Failure to thrive (FTT) poses a diagnostic dilemma for pediatricians. The kidney disorder that is considered most often is renal tubular acidosis (RTA). However, the prevalence of RTA may be overestimated, leading to unnecessary referrals for subspecialty evaluation. Moreover, preliminary data suggest that venous blood gas (VBG) testing may provide a more accurate measurement of the serum bicarbonate concentration than routine biochemical testing. OBJECTIVE: 1) To compare the results of bicarbonate measurements by using VBG and routine clinical biochemistry methods under a variety of in vitro conditions; 2) to determine the frequency of RTA as a cause of FTT; and 3) to assess the utility of VBG measurement of serum bicarbonate in the clinical assessment of RTA. EXPERIMENTAL DESIGN AND METHODS: In blood samples collected from healthy volunteers, bicarbonate was measured by using a VBG apparatus and a clinical biochemistry analyzer under a variety of in vitro conditions including variation in time until sample processing (0-4 hours), variations in temperature (room temperature versus on ice), addition of sodium fluoride, or addition of heparin. A retrospective chart review was also performed of all children referred to the renal clinic for evaluation of FTT during the 5-year period of 1997 to 2002. The following data were collected for each case: demographic and clinical information and laboratory testing including serum bicarbonate determined by both routine biochemical testing and VBG analysis. Data are reported as mean +/- standard deviation. RESULTS: In the in vitro studies, VBG determination of bicarbonate concentration consistently yielded a value that was 3 to 6 mmol/L higher than routine biochemical analysis regardless of whether the sample was processed immediately or up to 4 hours later, maintained at room temperature or on ice until the measurement was performed, or the sample tube contained sodium fluoride or heparin. Thirty-six children were referred to exclude a renal etiology of FTT with a presumptive diagnosis of RTA in all cases. The patient group was comprised of 16 males and 20 females whose ages ranged from 4 to 156 months (mean: 27 +/- 33 months). The serum bicarbonate concentration determined by biochemical testing was 18 +/- 4 mmol/L, whereas the bicarbonate level by VBG was 24 +/- 3 mmol/L. The mean difference between the bicarbonate by VBG and bicarbonate by routine biochemistry measurements was 5.6 +/- 4.4. Only 1 child (2.8%) was confirmed to have RTA. CONCLUSIONS: RTA is a rare renal cause of FTT in children. VBG determination of serum bicarbonate yielded a significantly higher value than the result obtained by routine biochemical testing under both in vitro and in vivo conditions. These data suggest that reliance on routine biochemical testing results in an overestimation of the importance of RTA as a cause of FTT. We recommend the use of a VBG determination of serum bicarbonate concentration for the evaluation of a child with FTT who is thought to have a metabolic acidosis. Adoption of this practice will reduce the number of children suspected of having RTA and decrease the need for referral to a nephrologist for further evaluation.

Acidosis, Renal Tubular↗
PubMed2002

Perinatal neuroendocrine regulation. Development of the circadian time-keeping system.

During gestation, the perinatal neuroendocrine axis keeps clock time. In primates, the suprachiasmatic nucleus (biological clock in mammals), shows oscillatory function by midgestation. There is evidence in rodents that the mother, during pregnancy, entrains the fetal suprachiasmatic nucleus (SCN) and newborn circadian rhythms. We are investigating the role of maternal melatonin as an entraining signal for the newborn circadian time-keeping system in the Cebus apella (New World non-human primate). Twenty-four hour rhythms of temperature and cortisol are present in the 4 days old C. apella newborn. Preliminary data suggests that inhibition of maternal melatonin by exposing pregnant females to constant light alters these rhythms. We have found binding sites for melatonin and expression of mRNA for Mel 1A receptor in hypothalamus, kidney and testis. These preliminary results suggest that maternal melatonin may play a role in relating the perinatal circadian time-keeping system to environmental signals.

Animals↗