Thyroid Disruptors: Extrathyroidal Sites of Chemical Action and Neurodevelopmental Outcome-An Examination Using Triclosan and Perfluorohexane Sulfonate.

Many xenobiotics are identified as potential thyroid disruptors due to their action to reduce circulating levels of thyroid hormone, most notably thyroxine (T4). Developmental neurotoxicity is a primary concern for thyroid disrupting chemicals yet correlating the impact of chemically induced changes in serum T4 to perturbed brain development remains elusive. A number of thyroid-specific neurodevelopmental assays have been proposed, based largely on the model thyroid hormone synthesis inhibitor propylthiouracil (PTU). This study examined whether thyroid disrupting chemicals acting distinct from synthesis inhibition would result in the same alterations in brain as expected with PTU. The perfluoroalkyl substance perfluorohexane sulfonate (50 mg/kg/day) and the antimicrobial Triclosan (300 mg/kg/day) were administered to pregnant rats from gestational day 6 to postnatal day (PN) 21, and a number of PTU-defined assays for neurotoxicity evaluated. Both chemicals reduced serum T4 but did not increase thyroid stimulating hormone. Both chemicals increased expression of hepatic metabolism genes, while thyroid hormone-responsive genes in the liver, thyroid gland, and brain were largely unchanged. Brain tissue T4 was reduced in newborns, but despite persistent T4 reductions in serum, had recovered in the PN6 pup brain. Neither treatment resulted in a low dose PTU-like phenotype in either brain morphology or neurobehavior, raising questions for the interpretation of serum biomarkers in regulatory toxicology. They further suggest that reliance on serum hormones as prescriptive of specific neurodevelopmental outcomes may be too simplistic and to understand thyroid-mediated neurotoxicity we must expand our thinking beyond that which follows thyroid hormone synthesis inhibition.

Clinical trial readiness study of distal myopathy and dysphagia in nephropathic cystinosis.

BACKGROUND: Nephropathic cystinosis is a lysosomal storage disorder with late-onset systemic complications, such as myopathy and dysphagia. Currently employed outcome measures lack sensitivity and responsiveness for dysphagia and myopathy, a limitation to clinical trial readiness. METHODS: We evaluated 20 patients with nephropathic cystinosis in two visits over the course of a year to identify outcomes sensitive to detect changes over time. Patients also underwent an expiratory muscle strength training program to assess any effects on aspiration and dysphagia. RESULTS: There were significant differences in the Timed Up and Go Test (TUG) and Timed 25-Foot Walk (25-FW) between baseline and 1-y follow-up (P < .05). Maximum expiratory pressure (MEP) and peak cough flow (PCF) significantly improved following respiratory training (P < .05). CONCLUSIONS: Improved respiratory outcomes may enhance patients ability to expel aspirated material from the airway, stave off pulmonary sequelae associated with chronic aspiration, and yield an overall improvement in physical health and well-being.

Clinical myopathy in patients with nephropathic cystinosis.

BACKGROUND: Nephropathic cystinosis is a lysosomal storage disorder. Patient survival years after renal transplantation has revealed systemic complications including distal myopathy and dysphagia. METHODS: We evaluated 20 adult patients with nephropathic cystinosis using patient-reported and clinical outcome measures. Standard motor measures, video fluoroscopy swallow studies, and tests of respiratory function were performed. We also used Rasch analysis of an initial survey to design a 16-item survey focused on upper and lower extremity function, which was completed by 31 additional patients. RESULTS: Distal myopathy and dysphagia were common in patients with nephropathic cystinosis. Muscle weakness ranges from mild involvement of intrinsic hand muscles to prominent distal greater than proximal weakness and contractures. CONCLUSIONS: In addition to further characterization of underlying dysphagia and muscle weakness, we propose a new psychometrically devised, disease specific, functional outcome measures for distal myopathy in patients with nephropathic cystinosis.

A transient window of hypothyroidism alters neural progenitor cells and results in abnormal brain development.

Cortical heterotopias are clusters of ectopic neurons in the brain and are associated with neurodevelopmental disorders like epilepsy and learning disabilities. We have previously characterized the robust penetrance of a heterotopia in a rat model, induced by thyroid hormone (TH) disruption during gestation. However, the specific mechanism by which maternal TH insufficiency results in this birth defect remains unknown. Here we first determined the developmental window susceptible to endocrine disruption and describe a cellular mechanism responsible for heterotopia formation. We show that five days of maternal goitrogen treatment (10 ppm propylthiouracil) during the perinatal period (GD19-PN2) induces a periventricular heterotopia in 100% of the offspring. Beginning in the early postnatal brain, neurons begin to aggregate near the ventricles of treated animals. In parallel, transcriptional and architectural changes of this region were observed including decreased Sonic hedgehog (Shh) expression, abnormal cell adhesion, and altered radial glia morphology. As the ventricular epithelium is juxtaposed to two sources of brain THs, the cerebrospinal fluid and vasculature, this progenitor niche may be especially susceptible to TH disruption. This work highlights the spatiotemporal vulnerabilities of the developing brain and demonstrates that a transient period of TH perturbation is sufficient to induce a congenital abnormality.

Safety and Efficacy of Botulinum Toxin A in Children Undergoing Lower Limb Lengthening and Deformity Correction: Results of a Double-blind, Multicenter, Randomized Controlled Trial.

BACKGROUND: Lengthening of the lower limb is a complex procedure in which pain management and complications such as pin-site infections and muscle contractures impact the family and affect the child's quality of life. As a result, the paralytic and antinociceptive actions of neurotoxins may be indicated in managing these complications; however, few studies have explored ways to improve outcomes after lengthenings. The objective of this study was to evaluate the safety and efficacy of botulinum toxin A (BTX-A) in children undergoing lower limb lengthenings and deformity correction. METHODS: Participants with a congenital or acquired deformity of the lower extremity requiring surgery to one limb were randomized to receiving either BTX-A as a single dose of 10 units per kilogram body weight, or an equivalent volume of saline solution. Pain, medication, quality of life, and physical function were assessed at different time-points. Adverse events were recorded in all participants. T test and χ tests were used to compare potential differences across both groups. RESULTS: Mean age of the 125 participants was 12.5 years (range, 5 to 21 y), and lengthenings averaged 4.2 cm. Maximum pain scores on day 1 postoperatively were lower in the BTX-A group (P=0.03) than in the placebo group, and remained significant favoring botox when stratifying by location of lengthening (femur vs. tibia). Clinical benefits for BTX-A were found for 3 quality of life domains at mid-distraction and end-distraction. When stratifying according to location of lengthening, there were significantly fewer pin-site infections in the tibia favoring botox (P=0.03). The amount of adverse events and bone healing indices were no different in both groups. CONCLUSIONS: The clinical differences in quality of life, the lower pain on the first postoperative day, and the lower number of pin-site infections in the tibia favoring BTX-A support its use as an adjunctive treatment to the lengthening process. The detailed analyses of pain patterns help inform families on the pain expectations during lower limb lengthenings. The amount of adverse events were no different in both groups, and bone healing rates were similar, indicating that the use of BTX-A in children undergoing limb lengthening and deformity correction is safe. LEVEL OF EVIDENCE: Level I.

Early urologic complications after pediatric renal transplant: a single-center experience.

BACKGROUND: Urologic complications cause substantial morbidity in the pediatric population after renal transplantation, but their impact on graft survival and transplant costs is poorly understood. In this retrospective review, we evaluated the records of all pediatric renal transplant recipients at our center from 1995 to 2004. METHODS: Patient demographics, presence of urinary leak, stricture, compression, or vesicoureteral reflux, and hospital costs were analyzed. Univariable analysis identified predictors of complications and of need for reoperation, and Kaplan-Meier analysis was used to assess graft survival in relation to urinary complications. RESULTS: One hundred forty-seven children received renal transplants; mean follow-up was 1478+/-965 days. Nine (6.1%) patients had urologic complications and seven (4.8%) patients developed vesicoureteral reflux requiring reoperation. Sex, ischemia time, race, previous transplant, donor type, nephrectomy technique, and stent use did not affect the incidence of urologic complications. Previous urologic reconstruction and pretransplant ureteral pathologic conditions increased the risk of urologic complication and vesicoureteral reflux. Patients with urologic complications had equivalent graft survival, but triple the hospital costs of unaffected recipients. CONCLUSIONS: Prior urologic surgery is associated with increased risk of urologic complications posttransplant. Posttransplant urologic complications are associated with substantially increased costs in the first year after transplant, but not with decreased graft survival.

Immune response to rabies vaccination in pediatric transplant patients.

Children have become engaged in a wider variety of activities as the success of solid organ transplantation has improved. These activities can result in exposure to infectious agents for which there are no data documenting the efficacy of standard treatment in children on immunosuppressive therapy. This is a retrospective review of five OLT patients and three RT patients who were potentially exposed to rabies during camp. They completed the immunoprophylaxis treatment for rabies exposure outlined by the CDC in the 2003 Red Book. Rabies titers were followed for six to 12 months post-immunization. All five OLT patients were on tacrolimus. All three RT patients were on tacrolimus, mycophenolate mofetil, and prednisone. At the time of exposure median age was 10.0 yr (8.4-17.3). None of the subjects developed rabies. A positive rabies titer, indicative of successful immunization, was present by one month in seven subjects and all subjects by six months. Rabies vaccination in pediatric transplant patients is safe and associated with the successful production of antirabies titers.

Developing clinical protocols for nursing practice: improving nephrology care for children and their families.

Improving and maintaining quality patient care through the development and implementation of clinical protocols is an important facet in our health care system. Identifying the need for clinical protocols, developing and maintaining the protocols, and defining the specific role of pediatric nephrology nurses in this process is presented herein. To illustrate the process we have included two examples of current clinical protocols utilized by our division.

Successful renal transplantation following prior bone marrow transplantation in pediatric patients.

Improving survival rates following pediatric bone marrow transplantation (BMT) will likely result in greater numbers of children progressing to end-stage renal disease (ESRD) because of prior chemotherapy, irradiation, sepsis, and exposure to nephrotoxic agents. Renal transplantation remains the treatment of choice for ESRD; however, the safety of renal transplantation in this unique population is not well established. We report our experience with living related renal transplantation in three pediatric patients with ESRD following prior BMT. Two patients with neuroblastoma and ESRD because of BMT nephropathy, and one patient with Schimke immuno-osseous dysplasia and ESRD because of immune complex mediated glomerulonephritis and nephrotic syndrome. Age at time of BMT ranged from 2 to 7 yr. All patients had stable bone marrow function prior to renal transplantation. Age at renal transplant ranged from 8 to 14 yr. All three patients have been managed with conventional immunosuppression, as no patient received a kidney and BMT from the same donor source. These patients are currently 7 months to 6 yr status post-living related transplant. All have functioning bone marrow and kidney transplants, with serum creatinine levels ranging 0.6-1.2 mg/dL. There have been no episodes of rejection. One patient with a history of grade III skin and grade IV gastrointestinal-graft-vs.-host disease (GI-GVHD) prior to transplantation, had a mild flare of GI-GVHD (grade I) post-renal transplant and is currently asymptomatic. The incidence of opportunistic infection has been comparable with our pediatric renal transplant population without prior BMT. One patient was treated for basal cell carcinoma via wide local excision. Renal transplantation is an excellent option for the treatment of pediatric patients with ESRD following BMT. Short-term results in this small population show promising patient and graft survival, however long-term follow-up is needed. Pre-existing immune system impairment and bone marrow function should be taken into consideration when weighing different immunosuppressive agents for renal transplantation. Patients who have undergone renal transplantation following BMT are at high risk for opportunistic infections and malignancy, and need life-long medical surveillance.

Limitations of EBV-PCR monitoring to detect EBV associated post-transplant lymphoproliferative disorder.

Post-transplant lymphoproliferative disorder (PTLD) represents a significant threat to the survival of pediatric transplant recipients. Epstein-Barr (EBV) viral load monitoring using polymerase chain reaction (PCR) has been reported to have a variable sensitively with relatively higher specificity as in an indicator of the development of PTLD. We report two cases of pathologically confirmed PTLD in children who failed to develop sustained increases in their EBV-PCR determined viral loads. We suggest that clinicians should be aware of the potential for false-negative results of EBV-PCR in pediatric transplant recipients.