A Neighboring Aromatic-Aromatic Amino Acid Combination Governs Activity Divergence between Tomato Phytoene Synthases.

Carotenoids exert multifaceted roles to plants and are critically important to humans. Phytoene synthase (PSY) is a major rate-limiting enzyme in the carotenoid biosynthetic pathway. PSY in plants is normally found as a small enzyme family with up to three members. However, knowledge of PSY isoforms in relation to their respective enzyme activities and amino acid residues that are important for PSY activity is limited. In this study, we focused on two tomato (Solanum lycopersicum) PSY isoforms, PSY1 and PSY2, and investigated their abilities to catalyze carotenogenesis via heterologous expression in transgenic Arabidopsis (Arabidopsis thaliana) and bacterial systems. We found that the fruit-specific PSY1 was less effective in promoting carotenoid biosynthesis than the green tissue-specific PSY2. Examination of the PSY proteins by site-directed mutagenesis analysis and three-dimensional structure modeling revealed two key amino acid residues responsible for this activity difference and identified a neighboring aromatic-aromatic combination in one of the PSY core structures as being crucial for high PSY activity. Remarkably, this neighboring aromatic-aromatic combination is evolutionarily conserved among land plant PSYs except PSY1 of tomato and potato (Solanum tuberosum). Strong transcription of tomato PSY1 likely evolved as compensation for its weak enzyme activity to allow for the massive carotenoid biosynthesis in ripe fruit. This study provides insights into the functional divergence of PSY isoforms and highlights the potential to rationally design PSY for the effective development of carotenoid-enriched crops.

Outcome of Mini-percutaneous Nephrolithotomy for Renal Stones in Infants and Preschool Children: A Prospective Study.

OBJECTIVE: To assess the safety and efficacy of Miniperc for renal stones in preschool-age patients. To the best of our knowledge, this may be the first prospective study on this subject. Reports on Miniperc are still few and mostly retrospective using a sheath size of ≥ 18Fr, which is still relatively large for young children. PATIENTS AND METHODS: From January 2012 to May 2013, Miniperc was performed for 26 children (≤ 6 years old) with renal calculi <5 cm through 14Fr sheath using a 9.5Fr semirigid ureteroscope with Holmium:yttrium-aluminum-garnet laser lithotripsy. Effects of different factors on operative time, complications, and stone-free rate (SFR) were compared using chi-square, Fischer exact, or Mann-Whitney tests as appropriate using SPSS v15.0. RESULTS: Primary SFR, SFR after retreatment, and SFR after auxiliary extracorporeal shock wave lithotripsy (ESWL) were 77%, 85%, and 92%, respectively. Retreatment rate was 8%. Auxiliary ESWL was done in 11%. Complications were bleeding (8%), hematuria and blood transfusion (4%), renal pelvis perforation (4%), leakage (8%), and fever (15%). Operative time was significantly prolonged in multiple (>2) stones (P = .006), calyceal stones (P = .002), or stone size ≥ 30 mm (P = .022). SFR was significantly lower in children with >2 stones (P = .028) and increased stone size ≥ 30 mm (P = .014). CONCLUSION: Miniperc is a safe and effective minimally invasive procedure for pediatric renal stones using 14Fr access sheath. SFR was significantly lower in children with >2 stones or increased stone size ≥ 30 mm. This was overcome by retreatment and auxiliary ESWL.

Effect of size and site on the outcome of extracorporeal shock wave lithotripsy of proximal urinary stones in children.

OBJECTIVE: To determine the effect of location and size of stones on the outcome of extracorporeal shock wave lithotripsy (ESWL) in children. PATIENTS AND METHODS: In 2008-2010, 150 children (median age 6.6 years) with radio-opaque ureteric and renal stones measuring ≤4 cm were treated. Exclusion criteria were coagulation disorders, pyelonephritis, distal obstruction, non-functioning kidney and hypertension. ESWL was performed under general anesthesia. Follow up period was 5-22 months. RESULTS: 186 stones were treated: 76 calyceal, 92 pelvic and 18 proximal ureteral. Mean stone size was 1.3 cm. A total of 312 sessions were performed (mean per stone = 1.67 sessions). The mean number of shock waves per session was 2423.68. Overall stone-free rate was 89.24%. Having a calyceal location did not significantly affect the stone-free rate (p = 0.133). The failure rate was significantly higher (66.7%) in stones >3 cm in size (p < 0.001). Complications were encountered in 18 patients; 2 underwent auxillary ureteroscopy and 4 uretrolithotomy for treatment of steinstrasse. CONCLUSION: ESWL is a safe and effective method for treatment of stones up to 2 cm in children. Rate of auxillary procedures increases in stones >2 cm in size. About 80% of failures were associated with stone size >1.35 cm while 52.3% of completely cleared stones were associated with size <1.35 cm.

Renal recoverability in infants with obstructive calcular anuria: is it better than in older children?

OBJECTIVE: Urolithiasis in infants can cause considerable morbidity. The literature regarding calcular anuria in this age group is very defective. Our aim was to evaluate impact of intervention on renal recoverability in these infants. PATIENTS AND METHODS: A series of 24 patients presenting with obstructive calcular anuria were included in this study. Mean age was 16.5 ± 6.2 months. They were treated either by initial urinary diversion or definitive endoscopic (ureteroscopy or JJ stenting with medical alkalinization) or open surgical (ureterolithotomy or pyelolithotomy) treatment. RESULTS: Mean serum creatinine was 5.8 ± 2.6 mg/dl. Initial peritoneal dialysis and/or urinary diversion was needed in 11 patients (45.8%). Open surgical treatment was applied in 5 (20.8%), endoscopic treatment was applied in 15 (62.5%), while combined treatment was applied in 4 (16.6%) patients. All patients had normal serum creatinine on discharge. Three (12.5%) had residual stones which were cleared by 2ry ureteroscopic intervention at 6 months. The overall complication rate in this study was 12.5% in the form of postoperative leakage (1) and postoperative fever (2). No mortality or development of chronic renal failure was reported at 6 months follow up. In comparison with these results, a previous study carried out in our centre on an older age group had a higher complication rate (28%) with higher mortalities and lower renal function recoverability rate (94%). CONCLUSIONS: Appropriate and timely medical and surgical management of calcular anuria will mostly lead to full recovery of renal functions. In comparison with older children, renal prognosis in those less than 2 years seems more favorable.

Renal pelvis reduction during dismembered pyeloplasty: is it necessary?

OBJECTIVE: To compare treatment results in patients who underwent pyeloplasty with and without pelvic reduction for ureteropelvic junction obstruction (UPJO). METHODS: This randomized prospective study involved 40 patients, all diagnosed with unilateral UPJO; 20 each were randomly selected to undergo open dismembered pyeloplasty with pelvic reduction (group A) or pelvis-sparing pyeloplasty (group B). Patients were evaluated with ultrasound and DPTA renography scans 6 months postoperatively. Mean follow-up was 9 months. RESULTS: The mean age in group B was 5.71 ± 6.36 years; in group A it was 4.81 ± 6.78 years. There was a decrease in mean anteroposterior renal pelvic diameter (from 49.9 to 26.35 ± 0.949 mm in A and 50.9 to 30.8 ± 1.556 mm in B) with improvement of split renal function (from 39 ± 22.47% to 42.4 ± 22.13% in A and 34.92 ± 16.79% to 38.8 ± 19.66% in B), glomerular filtration rate (from 37.25 ± 15.33 to 41.7 ± 19.34 ml/min in A and 31.3 ± 18.50 to 38.1 ± 23.23 ml/min in B) and draining curves on the 6-month scans, but without any significant difference between groups (p > 0.05). Two cases in group A and three in group B needed redo pyeloplasty, but without any significant difference in failure rate. CONCLUSION: Excision of the pelvis is not necessary in dismembered pyeloplasty procedures. We had similar surgical outcomes for patients with or without pelvis reduction.

Assessment of recoverability of kidney function in children with obstructive calcular anuria: multicenter study.

OBJECTIVE: Urolithiasis in children can cause considerable morbidity. Our aim was to evaluate the impact of intervention on the recoverability of kidney functions. MATERIALS AND METHODS: This prospective study included 93 children (66 boys and 27 girls) with median age of 3 years (range 0-14). Inclusion criteria were presence of anuria, oliguria, serum creatinine >2 mg% and/or hyperkalemia ≥ 6 mmol/L. The mean duration of anuria or oliguria was (mean ± SE) 5.3 ± 0.4 days. On presentation, mean plasma creatinine was 6.5 ± 0.29 mg/dl with a mean estimated glomerular filtration rate (eGFR) of 14 ml/min and creatinine clearance (CC) of 8.24 ml/min. Dialysis was performed in 21 (22.6%) patients. When condition allowed, emergency surgery was performed. RESULTS: Mean follow up was 1.5 years with compliance of 82%. At the end of treatment, 83% of patients had complete clearance of calculi. Mean plasma creatinine after treatment was 3.3 ± 0.35 mg/dl with an average GFR of 24.5 ml/min. After treatment renal function returned to normal in 57%, improved in 27% and deteriorated in 16% of children. Renal function recoverability rate was 94.6%. Chronic renal failure developed in 3 (3.2%) patients and 2 (2.2%) patients died. When absolute plasma creatinine concentration [P(cr)] improved 20-50% the eGFR and CC were doubled, and when improved 50-70% eGFR and CC tripled. Beyond 70% improvement in [P(cr)], eGFR and CC improved 7-8 times. Using Spearman's correlation, the mode of presentation and the type of management had a significant correlation with renal function outcome (P = 0.019 and 0.013 respectively). CONCLUSION: Urgent management of calcular anuria both medically and surgically is the cornerstone for favorable outcome. The mode of presentation and the type of management are significant factors affecting final renal function outcome.