Surface figure correction with roughness reduction using carbon-doped platinum film for high-precision X-ray mirror fabrication.

To obtain the surface shape of an X-ray mirror with high precision, a differential deposition method was used instead of a direct removal method. To modify the mirror surface shape using the differential deposition method, it is necessary to coat it with a thick film, and the co-deposition method is used to suppress the increase in surface roughness. The addition of C to the Pt thin film, which is often used as an X-ray optical thin film, resulted in lower surface roughness compared with that with the Pt coating alone, and the stress change according to the thin film thickness was evaluated. Differential deposition controls the speed of the substrate during coating based on continuous motion. The stage was controlled by calculating the dwell time through deconvolution calculations based on the accurate measurement of the unit coating distribution and target shape. We successfully fabricated an X-ray mirror with high precision. This study indicated that an X-ray mirror surface could be manufactured by modifying the surface shape at a micrometer level through the coating. Changing the shape of existing mirrors can not only result in the manufacture of high-precision X-ray mirrors but also improve their performance.

Prediction of vesicoureteral reflux in children with febrile urinary tract infection using relative uptake and cortical defect in DMSA scan.

BACKGROUND: Vesicoureteral reflux (VUR) is an important urologic anomaly that causes renal injury in children with febrile urinary tract infection (UTI). The present study aimed to evaluate the associations of abnormalities detected on technetium-99m-labeled dimercaptosuccinic acid (DMSA) scans, focusing on the association with VUR of the levels of relative decrease in kidney function and cortical defects after a first febrile UTI in children. METHODS: All 171 children underwent ultrasonography, DMSA scan and voiding cystourethrography (VCUG). The features of ultrasound and DMSA scans were compared between patients with (n = 48) and without VUR (n = 123). The relative uptake (RU) by each kidney was derived from the absolute value of the differences between the value for RU of radionuclide in the right kidney and that in the left kidney. The extent of cortical defects (ECD) was graded according to the number of compartments that contained cortical defect in both kidneys (right upper/right lower, left upper/left lower). Receiver operating characteristic curves were constructed to examine the diagnostic value of these parameters of ultrasound and DMSA scans for predicting VUR. RESULTS: The ratio of patients having hydronephrosis on ultrasound or cortical defects on DMSA scan did not differ significantly between VUR and non-VUR groups. However, the absolute values of the RU and the scores for ECD were significantly higher in the VUR group than in the non-VUR group. The area under the curves for these two parameters were higher than those for the presence of hydronephrosis or the presence of cortical defects or both. CONCLUSION: Decreased relative function and increased extents of cortical defects on DMSA scan may be associated with the presence of VUR. These findings may assist pediatricians to decide whether febrile UTI children need to undergo VCUG.

High incidence of initial and late steroid resistance in childhood nephrotic syndrome.

BACKGROUND: Conventional wisdom states that greater than 80% of children with nephrotic syndrome (NS) respond to steroid treatment, remain steroid-sensitive during subsequent relapses, and consequently have a favorable long-term prognosis. In contrast, steroid resistance is believed to be associated with a high risk of developing chronic renal failure. Recent reports suggest that the histologic pattern of NS in children may be changing, but whether the change is accompanied by a parallel change in steroid sensitivity is unknown. METHODS: Initial and subsequent steroid responsiveness was evaluated in all children aged 1 to 18 years who presented with newly diagnosed NS to the 2 pediatric nephrology referral centers in southeastern Louisiana between 1994 and 2003. NS was defined as presence of edema, heavy proteinuria, and serum albumin concentration below 2.5 g/dL. Steroid sensitivity (SS) was defined as total resolution of proteinuria and edema, and partial response to steroids (PR) was defined as loss of edema with continuing proteinuria. RESULTS: There were 210 new cases of NS. Forty-one patients (20%) had immune complex glomerulonephritis. Six patients were excluded because of incomplete data availability. Of the remaining 163 patients, 115 (71%) were SS and 23 (14%) achieved PR during the initial 4 weeks of treatment; 25 (15%) were steroid-resistant (SR). Follow-up data were available for 91 of the 115 initially SS patients; 19 subsequently became steroid-resistant. Thus, at least 45% of the patients with new-onset NS did not have typical childhood steroid-responsive NS. Initial steroid resistance was more likely in African American children and in children with older age at onset (11.5 vs. 4.6 years). Development of steroid resistance after initial SS was associated with shorter interval to the first relapse (2.2 vs. 5.4 months) and having the first relapse during the initial steroid treatment. CONCLUSION: Compared to previous reports, our results show a higher incidence of initial and subsequent steroid resistance, characteristics not consistent with typical minimal change NS with a benign prognosis. The results suggest that in the current era, NS in children may not be as benign as indicated by earlier studies.

Effect of age, ethnicity, and glucocorticoid use on tacrolimus pharmacokinetics in pediatric renal transplant patients.

Tacrolimus has become an effective alternative to cyclosporine as a component of primary immunosuppression in pediatric renal transplant patients, but the information on the pharmacokinetic characteristics of tacrolimus in young patients is still limited. The primary objective of this study was to determine the effect of patient age, ethnicity, and concurrent steroid administration on tacrolimus pharmacokinetics in pediatric renal transplant patients. The study population consisted of 30 pediatric patients, age 1.5-18.6 yr, who received a kidney transplant between July 1999 and February 2004. After twice daily dosing was stabilized based on clinical judgment, at least 5 days postoperatively, tacrolimus levels were drawn prior to, and 1, 2, 4, 8, and 12 h after the morning dose. The mean dose of tacrolimus was 0.12 mg/kg/dose. Mean trough level was 11.9 +/- 5.0 ng/mL. Mean area under the curve (AUC) was 192 +/- 84 with a range of 78-360 h x (ng/mL). The correlation between trough level and AUC was only fair (r = 0.74); later time points correlated better with AUC, and an excellent correlation (r = 0.96) was obtained between the mean of trough and 2-h level (C(2)) and AUC. There was a negative correlation between age and dose per body weight (r = -0.68). African-American patients had marginally lower drug exposure with similar dosing. Three age groups (<5, 5-12, and >12 yr) were compared with respect to dosing and AUC. Despite similar AUC in all three groups, the mean dose per kg required to achieve the AUC was 2.7- and 1.9-fold higher in the <5 and 5-12-yr groups, respectively, compared with the >12-yr group. Nine of the 30 patients were on a totally steroid-free regimen. Their tacrolimus dose and trough levels were similar to those of steroid-exposed patients, but their mean AUC was 41% higher. Our results show an inverse correlation between age and required tacrolimus dose, wide interindividual variation, and greater exposure with steroid-free regimen despite no change in trough level.

Sudden blindness in a child with end-stage renal disease.

Continuous peritoneal dialysis (CPD) is the preferred modality for renal replacement therapy in children with end-stage renal disease. Anterior ischemic optic neuropathy (AION) is a rare complication in patients on CPD. AION is characterized by ischemic injury of the optic nerve caused by hypoperfusion of the posterior ciliary arteries. It presents with acute visual loss and disc swelling, without additional neurological findings. We report a 2-year-old child with end-stage renal disease on CPD who developed AION. He was dehydrated and received intravenous fluid on admission. Additional treatment included methylprednisolone and levodopa. On his 3rd admission day, his pupils became reactive to light and his vision showed improvement. The improvement in vision might be due to the early detection and aggressive treatment of hypotension. It is difficult to demonstrate whether steroids or levodopa played a role in the improvement of his vision. Prospective studies to evaluate the effectiveness of levodopa in the treatment of AION are warranted in this potentially devastating condition.