Dynamic tuning of photon-plasmon interaction based on three-dimensionally confined microtube cavities.

We present tunable coupling between surface plasmon resonances supported by a metal-nanoparticle-coated tip and three-dimensionally (3D) confined optical modes supported by a microtube cavity. The competition and transition between two types of coupling mechanisms, i.e., dielectric-dielectric and plasmon-dielectric coupling, are observed in the tunable system. Owing to the competition between the two coupling mechanisms, the resonant modes can be dynamically tuned to first shift from higher to lower energies and then revert to higher energy. Moreover, the unique spatial field distribution of 3D confined modes allows selective coupling of odd and even order axial modes with surface plasmon resonances.

Multiplexing and tuning of a double set of resonant modes in optical microtube cavities monolithically integrated on a photonic chip.

In this Letter, we experimentally demonstrate a monolithic integration of two vertically rolled-up microtube resonators (VRUMs) on polymer-based 1×5 multimode interference waveguides to achieve 3D multi-channel coupling. In this configuration, different sets of resonant modes are simultaneously excited at S-, C-, and L- telecom bands, demonstrating an on-chip multiplexing, based on a vertical-coupling configuration. Moreover, the resonant wavelength tuning and consequently the overlapping of resonant modes are accomplished via covering the integrated VRUMs by liquid. A maximum sensitivity of 330 nm/refractive index unit is achieved. The present work would be a critical step for the realization of massively parallel optofluidic sensors with higher sensitivity and flexibility for signal processing, particularly in a 3D-integrated photonic chip.

Optical microtube cavities monolithically integrated on photonic chips for optofluidic sensing.

Microtubular optical resonators are monolithically integrated on photonic chips to demonstrate optofluidic functionality. Due to the compact subwavelength-thin tube wall and a well-defined nanogap between polymer photonic waveguides and the microtube, excellent optical coupling with extinction ratios up to 32 dB are observed in the telecommunication relevant wavelength range. For the first time, optofluidic applications of fully on-chip integrated microtubular systems are investigated both by filling the core of the microtube and by the microtube being covered by a liquid droplet. Total shifts over the full free spectral range are observed in response to the presence of the liquid medium in the vicinity of the microtube resonators. This work provides a vertical coupling scheme for optofluidic applications in monolithically integrated so-called "lab-in-a-tube" systems.

Vertical optical ring resonators fully integrated with nanophotonic waveguides on silicon-on-insulator substrates.

We demonstrate full integration of vertical optical ring resonators with silicon nanophotonic waveguides on silicon-on-insulator substrates to accomplish a significant step toward 3D photonic integration. The on-chip integration is realized by rolling up 2D differentially strained TiO(2) nanomembranes into 3D microtube cavities on a nanophotonic microchip. The integration configuration allows for out-of-plane optical coupling between the in-plane nanowaveguides and the vertical microtube cavities as a compact and mechanically stable optical unit, which could enable refined vertical light transfer in 3D stacks of multiple photonic layers. In this vertical transmission scheme, resonant filtering of optical signals at telecommunication wavelengths is demonstrated based on subwavelength thick-walled microcavities. Moreover, an array of microtube cavities is prepared, and each microtube cavity is integrated with multiple waveguides, which opens up interesting perspectives toward parallel and multi-routing through a single-cavity device as well as high-throughput optofluidic sensing schemes.

Rolled-up TiO2 optical microcavities for telecom and visible photonics.

The fabrication of high-quality-factor polycrystalline TiO2 vertically rolled-up microcavities (VRUMs) by the controlled release of differentially strained TiO2 bilayered nanomembranes, operating at both telecom and visible wavelengths, is reported. Optical characterization of these resonators reveals quality factors as high as 3.8×10³ in the telecom wavelength range (1520-1570 nm) by interfacing a TiO2 VRUMs with a tapered optical fiber. In addition, a splitting in the fundamental modes is experimentally observed due to the broken rotational symmetry in our resonators. This mode splitting indicates coupling between clockwise and counterclockwise traveling whispering gallery modes of the VRUMs. Moreover, we show that our biocompatible rolled-up TiO2 resonators function at several positions along the tube, making them promising candidates for multiplexing and biosensing applications.

Early detection of acute kidney injury by serum cystatin C in critically ill children.

BACKGROUND: We prospectively evaluated whether serum cystatin C (CysC) detected acute kidney injury (AKI) earlier than basal serum creatinine (Cr). METHODS: In 107 pediatric patients at high risk of developing AKI, serum Cr and serum CysC were measured upon admission. Baseline estimated creatinine clearance (eCCl) was calculated using a CysC-based glomerular filtration rate (GFR) equation from a serum Cr measured at the pediatric intensive care unit (PICU) entrance. RESULTS: The median age was 10 months (interquartile range, 3-36 months). Serum Cr, serum CysC, and eCCl (mean ± standard deviation [range]) were 0.5 ± 0.18 mg/dl (0.2-1.1 mg/dl), 0.53 ± 0.78 (0.01-3.7 mg/l), and 72.55 ± 28.72 (20.6-176.2) ml/min per 1.73 m(2), respectively. The serum CysC level in patients with AKI was significantly higher than children with normal renal function (p < 0.001). The values for the cut-off point, sensitivity, specificity, and the area under curve (AUC) were determined for CysC as 0.6 mg/l, 73.9 %, 78.9 %, and 0.92 [95 % confidence interval (0.82-1)], respectively, and for Cr the values were 0.4 mg/dl, 68 %, 46.2 %, and 0.39, [95 % confidence interval (0.24-0.54)], respectively. The receiver operating characteristics (ROC) curve analysis revealed that CysC had a significantly higher diagnostic accuracy than eCCl (p < 0.001). CONCLUSIONS: Our results identify that the sensitivity of serum CysC for detecting AKI is higher than that of serum Cr in a heterogeneous pediatric intensive care unit (PICU) population.

Sphingosine phosphate lyase insufficiency syndrome: a systematic review.

BACKGROUND: Sphingosine-1-phosphate lyase insufficiency syndrome (SPLIS) or nephrotic syndrome type-14 is caused by biallelic mutations in SGPL1. Here, we conducted a systematic review to delineate the characteristics of SPLIS patients. METHODS: A literature search was performed in PubMed, Web of Science, and Scopus databases, and eligible studies were included. For all patients, demographic, clinical, laboratory, and molecular data were collected and analyzed. RESULTS: Fifty-five SPLIS patients (54.9% male, 45.1% female) were identified in 19 articles. Parental consanguinity and positive family history were reported in 70.9% and 52.7% of patients, respectively. Most patients (54.9%) primarily manifested within the first year of life, nearly half of whom survived, while all patients with a prenatal diagnosis of SPLIS (27.5%) died at a median [interquartile (IQR)] age of 2 (1.4-5.3) months (P = 0.003). The most prevalent clinical feature was endocrinopathies, including primary adrenal insufficiency (PAI) (71.2%) and hypothyroidism (32.7%). Kidney disorders (42, 80.8%) were mainly in the form of steroid-resistant nephrotic syndrome (SRNS) and progressed to end-stage kidney disease (ESKD) in 19 (36.5%) patients at a median (IQR) age of 6 (1.4-42.6) months. Among 30 different mutations in SGPL1, the most common was c.665G > A (p.Arg222Gln) in 11 (20%) patients. Twenty-six (49.1%) patients with available outcome were deceased at a median (IQR) age of 5 (1.5-30.5) months, mostly following ESKD (23%) or sepsis/septic shock (23%). CONCLUSION: In patients with PAI and/or SRNS, SGPL1 should be added to diagnostic genetic panels, which can provide an earlier diagnosis of SPLIS and prevention of ESKD and other life-threatening complications.

Urinary calcium and uric acid excretion in children with vesicoureteral reflux.

Urolithiasis is relatively common in children, and identifiable predisposing factors for stone formation, including metabolic and structural derangements, can be established in most cases. Vesicoureteral reflux (VUR) is a common cause of kidney stone formation. The pathophysiological mechanism of urolithiasis in reflux is related to urinary tract infection and urinary stasis, both of which promote urinary crystal formation, but metabolic causes, such as crystallurias (mostly hypercalciuria), may also be involved in this process. However, few studies on urinary calcium and uric acid excretion in children with VUR have been conducted. We have studied the frequency of hypercalciuria and hyperuricosuria in children with VUR and compared the results with those from a control group. The VUR group comprised 108 children with VUR (19 boys, 89 girls; age range 3 months to 12 years), and the control group comprised 110 healthy children without any history of reflux or urinary tract infection (30 boys, 80 girls; age range 2 months to 12 years). Fasting urine was analyzed for the calcium/creatinine (Ca/Cr) and uric acid/creatinine (UA/Cr) ratios. Hypercalciuria was more frequently diagnosed in the VUR patients than in the control group (21.3 vs. 3.6%; P = 0.0001). Significant differences between the two groups were also found for the mean Ca/Cr and UA/Cr ratios (P = 0.0001 and P = 0.0001, respectively). No differences were found in the urinary Ca/Cr or UA/Cr ratios related to VUR grading or unilateral/bilateral VUR in the patient group, with the exception of those for hypercalciuria and mild VUR (P = 0.03). The association of urinary stones and microlithiasis in the VUR group was 29.6%. Our results demonstrate that the frequency of hypercalciuria and hyperuricosuria was higher in pediatric patients with VUR than in healthy children. Knowing this relationship, preventive and therapeutic interventions for stone formation in VUR could be greatly expanded.

Clinical Outcomes of 141 Cases of Isolated Antenatal Hydronephrosis; An Observational Study.

INTRODUCTION: Hydronephrosis, a condition that is mostly congenital, is considered as the most common type of pediatric urinary tract disorder. The aim of this study was the evaluation of the prognosis and outcomes of hydronephrosis in cases of congenital hydronephrosis. METHODS: In a cross-sectional study, run in a tertiary clinic of pediatric nephrology, from 2015 to 2020, patients with fetal hydronephrosis were selected. Ultrasonography, urinalysis and kidney function tests were ordered for all patients and in the presence of hydronephrosis, repeated ultrasonography, voiding cystourethrography and dimercaptosuccinic acid scan were performed. In cases with evidence of obstruction, a diethylenetriamine pentaacetic acid scan and relative surgical procedures were performed. RESULTS: Among 141 cases, mean age was 8 ± 1.4 years and 80.9% were male. Partial or complete obstruction in the right and left kidney was found in 16.3 and 24.8% of patients, respectively. The degree of hydronephrosis was mild in 46.1%, moderate in 39%, and severe in 9.2% of the patients. At the last follow-up period, hydronephrosis recovered in 46% of the patients, while 54% experienced persistence or exacerbation of the disease. Meanwhile, 7.1% of patients showed neurogenic bladder, 19.1% urinary tract infection and 22.7% urinary stones. CONCLUSION: Our study revealed that fetal hydronephrosis ends in complete recovery following birth in 46% of the cases. However, in cases experiencing persistent or exacerbating hydronephrosis, optimized treatment and/or surgical intervention are required.  DOI: 10.52547/ijkd.6516.

Clinical course and outcome of children with steroid-sensitive nephrotic syndrome.

We conducted a retrospective study on children with primary nephrotic syndrome (NS) to evaluate the clinical course and outcome of children with steroid-sensitive NS (SSNS). The medical records of 226 children, median 3.46 years (min 1.00, max 15.08) who referred to our clinics with SSNS between January 1978 and September 2005 were reviewed and entered into the study. Minimum duration of follow-up was 5 years and maximum 20 years (median 7.25 years). Of 226 patients who were treated with corticosteroids, 38 (16.8%) had no relapse but the remaining 188 (83.2%) patients experienced several relapses of which 128 patients (56.6%) required additional immunosuppressive agents for the remission. Of these, 122 (95%) were treated with levamisole, 22 (17%) with cyclosporine, 36 (28%) with cyclophosphamide, and ten (7.8 %) treated with mycophenolate mofetil. Several patients had to switch from one medication to others due to lack of response. On the last follow-up visit, 64(28.3%) patients were still under treatment, some patients had taken all of the above-mentioned drugs but still had multiple recurrences. Only 103 (45.5%) patients were in remission off the drug more than 3 years. This study shows that nearly one-third of pediatric patients with SSNS experience frequent relapses despite the combination of multiple immunosuppressive medications, which may continue until adulthood.

Low defect and high electrical conductivity of graphene through plasma graphene healing treatment monitored with in situ optical emission spectroscopy.

Fundamental studies on graphene (Gr) and its real device applications have been affected by unavoidable defects and impurities which are usually present in synthesized Gr. Therefore, post treatment methods on Gr have been an important subject of research followed by the community. Here, we demonstrate a post-treatment of cm-sized CVD-grown graphene in a Radio Frequency-generated low-pressure plasma of methane and hydrogen to remove oxygen functional groups and heal the structural defects. The optimum plasma treatment parameters, such as pressure, plasma power, and the ratio of the gases, are optimized using in-situ optical emission spectroscopy. This way we present an optimal healing condition monitored with in situ OES. A twofold increase in the conductivity of plasma-treated Gr samples was obtained. Plasma treatment conditions give insights into the possible underlying mechanisms, and the method presents an effective way to obtain improved Gr quality.

Vesicoureteral reflux and primary bladder neck dysfunction in children: urodynamic evaluation and randomized, double-blind, clinical trial on effect of α-blocker therapy.

PURPOSE: Primary bladder neck dysfunction has been under diagnosed as a treatable cause of vesicoureteral reflux. We evaluated the effect of prazosin administration on vesicoureteral reflux resolution and urodynamic parameters in children with idiopathic primary reflux and primary bladder neck dysfunction. MATERIALS AND METHODS: A total of 62 children (mean ± SD age 7.9 ± 2.4 years) with documented vesicoureteral reflux and urodynamics proved primary bladder neck dysfunction were randomized to receive either 0.025 mg/kg α-blocker (prazosin, 40 patients) or placebo (22) nightly for 1 week with a subsequent increase to 2 divided doses. Patients were followed for 12 months with clinical evaluation and uroflowmetry performed every 2 months, and each patient underwent complete urodynamic study at 6-month intervals. RESULTS: In the placebo group no uroflowmetry or urodynamic parameter changed significantly at 1-year followup. A 60% decrease in reflux grade was observed in the treatment group compared to 17% in the placebo group. Mean maximal detrusor pressure, post-void residual and opening time were significantly decreased in both followup sessions in the prazosin group (p <0.05). Average flow rate improved from 4.30 to 12.80 ml per second at 6 months and to 13.10 ml per second at 12 months (both p <0.05). CONCLUSIONS: Special attention should be given to secondary causes of vesicoureteral reflux (such as primary bladder neck dysfunction, an underdiagnosed entity in children), since conventional treatment will most likely fail if these conditions are not addressed promptly. In this study prazosin was effective therapy for children with vesicoureteral reflux and primary bladder neck dysfunction.

Chronic Kidney Disease in Iran: First Report of the National Registry in Children and Adolescences.

PURPOSE: Knowing the epidemiological aspects of chronic kidney disease (CKD) in children is crucial for early recognition, identification of reversible causes, and prognosis. Here, we report the epidemiological characteristics of childhood CKD in Iran. MATERIALS AND METHODS: This cross-sectional study was conducted during 1991 - 2009. The data were collected using the information in the Iranian Pediatric Registry of Chronic Kidney Disease (IPRCKD) core dataset. RESULTS: A total of 1247 children were registered. The mean age of the children at registration was 0.69 ± 4.72 years (range, 0.25 -18 years), 7.79 ± 3.18 years for hemodialysis (HD), 4.24 ± 1.86 years for continuous ambulatory peritoneal dialysis (CAPD), and 3.4±1.95 years for the children who underwent the renal transplantation (RT) (P < .001). The mean year of follow-up was 7.19 ± 4.65 years. The mean annual incidence of CKD 2-5 stages was 3.34 per million age-related population (pmarp). The mean prevalence of CKD 2-5 stages was 21.95 (pmarp). The cumulative 1-, 5-, and 10-year patients' survival rates were 98.3%, 90.7%, and 84.8%, respectively. The etiology of the CKD included the congenital anomalies of the kidney and urinary tract (CAKUT) (40.01%), glomerulopathy (19.00%), unknown cause (18.28%), and cystic/hereditary/congenital disease (11.14%). CONCLUSION: The incidence and prevalence rate of pediatric CKD in Iran is relatively lower than those reported in Europe and other similar studies. CAKUT was the main cause of the CKD. Appropriate management of CAKUT including early urological intervention is required to preserve the renal function. Herein, the long-term survival rate was higher among the children with CKD than the literature.

Comparison between fractional excretions of urea and sodium in children with acute kidney injury.

Fractional excretion of sodium (FENa) has been said to be the most sensitive index for differentiating prerenal failure (PRF) from intrinsic renal failure (IRF). However, there are several instances of high FENa (>2%) in cases of PRF and low FENa (<1%) in IRF patients. In contrast, the fractional excretion of urea nitrogen (FEUN) is primarily dependent on passive forces, and many confounding variables that affect FENa have little effect on FEUN, if any. To compare FEUN with FENa, pediatric patients with acute kidney injury (AKI) were prospectively evaluated by history, physical examination, and obtaining appropriate laboratory data during a 1-year interval. Diagnosis of PRF or IRF was made in each patient, and renal failure indices were compared between two groups using chi-square and t test, as appropriate. Probability value (P value) <0.05 was considered significant. Receiver operating characteristic (ROC) plots for FEUN and FENa were drawn to compare the discriminative power of each index. Forty-three patients were enrolled in the study. There were 27 patients in the PRF and 16 in the IRF group. FENa was 2+/-0.4 in PRF and 4.5+/- 1% in IRF patients (P<0.05), and low FENa (<1%) was only seen in 44.4% of PRF patients, which was not statistically different from those with IRF (P>0.05). FEUN was 23.6+/- 4.9% in PRF and 41.6+/-4.8% in IRF patients (P<0.05), and low FEUN (<35%) was seen in 77.8% of the PRF group (P<0.05). Cutoff values of 30% and 1.6% were reached for FEUN and FENa, respectively. In conclusion, FEUN <35% had higher sensitivity and specificity than FENa <1% for differentiation of PRF from IRF.

Design and fabrication of a spatial light modulator using thermally tunable grating and a thin-film heater.

We propose the application of a thermally tunable grating as a spatial light modulator. The grooves of a square-well grating are filled with a liquid whose refractive index depends on temperature. The variation of optical characteristics of such a grating with respect to temperature is investigated theoretically and also by simulation and experiment. A thin-film heater is then used as a heat source. The relation between intensity of the first order of diffraction versus power consumption of the thin-film heater is investigated. Finally, a thin-film heater with a desired pattern is placed at the surface of the grating to fabricate spatial light modulator. By applying electrical current to different elements of the thin-film heater, the fabricated device can project a desired pattern on a screen using a 4f imaging system. The restrictions of such a device are discussed and another structure is proposed and discussed by numerical calculations to increase the ability of the device.

The outcome of Iranian children on continuous ambulatory peritoneal dialysis: the first report of Iranian National Registry.

BACKGROUND: Continuous ambulatory peritoneal dialysis is not a very common modality to treat Iranian children with end-stage renal disease; however, there is sometimes no choice but to offer this therapy to salvage the patient. Obviously, promotion in each program needs re-evaluation to find the pitfalls. Therefore, a nation-wide survey on pediatric continuous ambulatory peritoneal dialysis was conducted to find the cause of death or termination of dialysis. METHODS: All children, younger than 14 years old, treated by continuous ambulatory peritoneal dialysis in nine main pediatric nephrology wards in Iran between 1993 and 2006 were included in this historical cohort study. Patient and technique survival rates were determined. Kaplan-Mayer and Cox-regression analysis were used to compare the survival. 2 x 2 table was used to calculate the risk ratio. A P<0.05 was considered significant. RESULTS: One hundred twenty children with a mean age of 47.6 months were on continuous ambulatory peritoneal dialysis. The most frequent cause of renal failure was hereditary-metabolic-cystic disease. One hundred eighty-two peritoneal dialysis catheters were inserted surgically. The median first catheter exchange was 0.74 year (95%CI: 0.5 - 0.98). The most frequent cause of catheter replacement was catheter outflow failure due to displacement, adhesion, and infection (persistent peritonitis or tunnel infection). The mean patient survival was 1.22 years (95%CI: 0.91 - 1.53). The mortality rate was 55% before 1997, and 60% between 1998 and 2001, which declined to 23% after 2002 (P<0.05). Young age (<24 months) was the only independent factor that predicted mortality (P<0.05). The outcome of children was as follows: recovery of renal function (6.7%), renal transplantation (8.3%), switch to hemodialysis (16.7%), still on continuous ambulatory peritoneal dialysis (23.3%), death (43.3%), and lost to follow-up (1.7%). CONCLUSION: The mortality is still high among Iranian children on peritoneal dialysis. Young age is the most important factor influencing on survival and mortality.

Posterior urethral valve in a child presenting as recurrent epididymo-orchitis.

Epididymo-orchitis is an uncommon complication of posterior urethral valve. A four-year-old boy was admitted because of right-sided epididymo-orchitis. Scintigraphy of the scrotum showed increased uptake of radiotracer on the right side. The posterior urethral valve was disclosed by voiding cystourethrography. Ablation of the valve and antibiotic therapy made the patient free of symptoms.

Luminescent nanoparticles embedded in TiO2 microtube cavities for the activation of whispering-gallery-modes extending from the visible to the near infrared.

Luminescent nanoparticles (NPs) are deposited onto two dimensional (2D) pre-strained TiO2 nanomembranes by spin-coating. After rolling up the 2D differentially strained TiO2 nanomembranes into 3D microtube structures, the NPs are embedded within the tube windings. The embedded NPs serve as a light source for optical whispering-gallery-mode resonances under laser excitation, and therefore allow the TiO2 microtube to work as an active microcavity operating in emission mode. The spectral range of resonant modes can be tuned from the visible to the near infrared by embedding the proper NPs in the TiO2 tube wall. Rolled-up TiO2 microcavities combined with luminescent NPs could offer interesting opportunities in a variety of research fields, such as bio- and nanophotonics, optoelectronics, and optofluidics.