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Digital technologies have led to the emergence of many platforms in our economy today. In certain platform networks, buyers in one market purchase services from providers in many other markets, whereas in others, buyers primarily purchase services from providers within the same market. Accordingly, network interconnectivity—which measures the degree to which consumers in one market purchase services from service providers in a different market—varies across different industries. We examine how network interconnectivity affects interactions between an incumbent platform serving multiple markets and an entrant platform seeking to enter one of these markets. Our model yields several interesting results. First, even if the entrant can advertise at no cost, it still may not want to make every user in a local market aware of its service, as doing so may trigger a competitive response from the incumbent. Second, having more mobile buyers, which increases interconnectivity between markets, can reduce the incumbent’s incentive to fight and, thus, increase the entrant’s incentive to expand. Third, stronger interconnectivity between markets may or may not make the incumbent more defensible: when advertising is not costly and mobile buyers consume in both their local markets and the markets they visit, a large number of mobile buyers will increase the entrant’s profitability, thereby making it difficult for the incumbent to deter entry. However, when advertising is costly or mobile buyers only consume in the markets they travel to, a large number of mobile buyers will help the incumbent deter entry. When advertising cost is at an intermediate level, the entrant prefers a market with moderate interconnectivity between markets. Fourth, we find that even if advanced targeting technologies can enable the entrant to also advertise to mobile buyers, the entrant may choose not to do so in order to avoid triggering the incumbent’s competitive response. Finally, we find that the presence of network effects is likely to decrease the entrant’s profit. Our results offer managerial implications for platform firms and help understand their performance heterogeneity.

Objectives: Postnatal evaluation of vesicoureteral reflux (VUR) remains controversial in patients with antenatal hydronephrosis (HN). The objective of this study was to identify the significance of mild postnatal HN as a marker of VUR and its severity. Materials and Methods: Sonographic findings of 248 children (351 kidneys) with persistent postnatal HN were evaluated for the incidence and severity of primary VUR. Results: The majority of patients had mild (67.8%) HN, followed by moderate (27.6%) and severe (4.6%) HN. VUR was identified in 14.7% of patients with mild HN, 18.5% of patients with moderate HN, and 18.7% of patients with severe HN. About 11.44% of patients with mild HN had low-grade VUR, followed by moderate (45.71 %) and severe grades (42.85%). Conclusion: A large number (89%) of patients with mild HN had moderate to severe VUR. In this cohort, renal sonography was not a reliable method for the prediction of VUR and its severity in patients with mild postnatal HN. However, it was reliable for high grades of VUR. These results are limited due to the study design and the inability to generalize these findings. These results should be replicated across other multiple clinics, thereby recruiting more variety of patients, to validate these study recommendations.

Background: Hyponatremia/water intoxication has been considered a rare but serious complication of desmopressin (DDAVP) for the treatment of primary monosymptomatic nocturnal enuresis (PMNE). Objectives: This study aimed to identify the incidence and risk factors of serum sodium (Na) alterations in children with PMNE treated with oral or intranasal DDAVP. Methods: A total of 201 patients with PMNE were evaluated in 2 groups using intranasal (n = 127) or oral DDAVP (n = 74) for approximately 6 months. Treatment efficacy was defined as a more than 50% decrease in wet nights after 1 month of treatment. Serum Na was measured before, during, and after treatment in all patients. Predisposing factors of serum Na disturbance were evaluated concomitantly. Results: The mean age of patients was 8.8 ± 2.6 (5 - 17.5) years, and males outnumbered females (M/F = 1.68). Treatment efficacy was 100% in 93 (46.2%), and > 90% in 157 (78.1%) cases. Oral DDAVP had significantly more therapeutic effects than intranasal treatment (P = 0.024). However, serum Na had no significant difference between the 2 groups (P = 0.52). Hyponatremia occurred in 7 (3.5%) patients (3 in oral treatment and 4 in intranasal treatment; P = 0.73) with no significant correlation to age, gender, body weight, frequency of enuresis, and initial serum Na. However, decreased serum Na > 5 mEq/L was a significant risk factor for the prediction of hyponatremia in our patients (P < 0.001). Conclusions: Oral DDAVP had more therapeutic effects than intranasal treatment for the treatment of PMNE. Serum Na had no significant alteration in both oral and intranasal treatments, and hyponatremia was a rare complication of DDAVP, which occurred significantly in children with a > 5-mEq/L decrease of initial serum Na concentration. As a suggestion, monitoring serum Na is not an essential follow-up in asymptomatic patients in DDAVP treatment.

Introduction: Nephrolithiasis has been increasingly recognized in recent years. Urine metabolic abnormality is the main cause of renal stone in children. Therefore, identification and medical treatment of metabolic abnormalities have been suggested as an alternative approach to surgical treatments. Objectives: This study was performed to evaluate the therapeutic effect of urine alkalinization and metabolic management in children with renal stone. Patients and Methods: A total of 300 children (from 408 renal clinics) with nephrolithiasis were enrolled in this study. All of them were treated by supportive managements, including urine alkalinization and specific medical treatment of underlying metabolic abnormality. Improvement was defined as stone resolution, stone passage or decrease of stone dimension. Results: Mean age at diagnosis was 28.7 ± 2.6 months (1-150 months). About 78.8% of patients had metabolic abnormality, of which, hypercalciuria (51.7%) and hypocitraturia (33.4%) were the most common causes, respectively. Resolution of renal stone occurred in 89.7% of patients after one year follow up, more in children less than 5 years (P=0.003), and stones smaller than 5 mm (PConclusion: Pharmacologic treatment is recommended in young children with small nephrolithiasis. Pharmacologic treatment also suggested as a primary intervention in children with uncomplicated large renal stones, and prior to invasive surgical management.

Vesicoureteral reflux (VUR) is the most common congenital urinary tract abnormality in children. The objective of this study was to evaluate the diagnostic value of urine neutrophil gelatinase-associated lipocalin (NGAL) in children with primary vesicoureteral reflux (VUR). A total of 69 patients were evaluated in 2 groups with (32) and without (37) VUR. Patients with secondary VUR, infectious or inflammatory disorders, obstructive uropathies, and acute or chronic kidney disease were excluded. Urine NGAL level was measured by ELISA kit. Mean age of children with VUR was 36.84 ± 28.16, compared to those without VUR 32.32 ± 29.08, with no significant difference (p = 0.51). Mean urine NGAL (p = 0.012) and urine NGAL/Cr (p = 0.003) were higher in patients with VUR. In addition, urine NGAL/Cr increased significantly in patients with decreased parenchymal function, compared to those with normal DMSA scan. Using the cutoff value of 0.888, urine NGAL had 84% sensitivity and 81% specificity for diagnosis of VUR. Based on AUC (0.86), urine NGAL had acceptable diagnostic accuracy in children with VUR. The results of this study support the evidence that urine NGAL/Cr is a sensitive, specific and accurate biomarker for diagnosis of children with primary VUR.

Congenital chloride diarrhea of infancy is a life threatening disease. We discuss two boys with congenital chloride diarrhea over a long time period before and after kidney transplantation. In the first case, prenatal sonography revealed polyhydramnios and generalized bowel loop distention. The genetic study confirmed congenital chloride diarrhea of infancy. Multiple episodes of severe dehydration, hyponatremia and acute tubular necrosis were seen during the follow up period. He underwent a year of hemodialysis before kidney transplantation. Three periods of improvement concerning diarrhea occurred with the use of corticosteroids, taken for other reasons. These improvements were seen after prednisolone administration for mastoiditis and following prednisolone administration for kidney transplantation. The second case was a 3.5 year old boy who is the cousin of the first case. He was referred to hospital with chronic watery diarrhea, metabolic alkalosis, hypokalemia, hyponatremia and failure to thrive in the first year of life. He was also treated with prednisolone and showed significant improvement.

Background: Urinary tract infection is one of the most common bacterial infections in children. Zinc is the second most abundant mineral in the body involved in the growth, cell division, and regulation of immune system activity. In studies, zinc administration has been effective in improving pneumonia and gastroenteritis in children, and today, zinc is used to treat acute gastroenteritis in children. Due to the increasing use of various supplements in children and the importance of urinary tract infection and its complications in children. Objectives: This study was performed to compare serum zinc levels between children with febrile urinary tract infection and healthy children. Methods: In this case-control study, serum zinc was measured in 60 healthy children and 60 children with febrile urinary tract infection, without any underlying disease, by an Auto analyzer. Data were analyzed by SPSS version 22 software. Results: The difference in serum zinc levels between the two groups was not statistically significant. There was no statistically significant difference in zinc deficiency between the groups. Serum zinc levels were not associated with sex, age, frequency of urinary tract infection, the severity of leukocytosis, the severity of ESR increase, CRP, and length of hospitalization. In the age group of 24 - 72 months, a significant linear relationship was observed between serum zinc levels and weight. The incidence of urinary tract infections was higher in girls, and this difference was statistically significant in all groups, except in age groups 6 - 12 months and above 72 months. Conclusions: This study showed that low serum zinc levels did not increase the risk of febrile urinary tract infection in children. Therefore, prescribing zinc supplements to treat or prevent urinary tract infections requires further studies.

Considering the predictive role of the relatively low urinary citrate for stone formation, especially in hypercalciuric patients, this study is aimed at comparing urine calcium to citrate (Ca/Cit) ratio in 3 groups of children, including patients with idiopathic hypercalciuria with and without renal stone as well as the healthy children.This study was carried out on 96 children (2 to 12 years old) referred to a pediatric nephrology clinic in the city of Ahvaz, Southwest Iran. All the children underwent renal ultrasonography, urinalysis, and measurement of random nonfasting urine Ca, Cr, and citrate. Those with secondary hypercalciuria, urinary tract malformations, and/or functional abnormalities of the gastrointestinal tract were excluded from the study.The mean Ca/Cit. ratio (mg/mg) in the three groups, including children with hypercalciuric with and without renal stones and the healthy children (control group), was 0.44 ± 0.14, 0.39 ± 0.13, and 0.19 ± 0.08, respectively, which showed a significant difference (P .001). There was also a significant difference in Ca/Cit ratio between the first and the control group by Tukey's range test (P .001). Mean urinary Ca/Cit ratio in those with a positive family history of urolithiasis within three groups was 0.42 ± 0.17 and in those with a negative family history was 0.32 ± 0.16 (P = .013). Mean Ca/Cit. ratio (mg/mg) of 0.25 showed a sensitivity of 90.6% (confidence interval: 75.7-96.7%) and a specificity of 81.2% (confidence interval: 64.7-91.1%) to differentiate between the renal stone group and the control group.High Ca/Cit ratio can predict stones formation in hypercalciuric patients, especially in those with a positive family history of urolithiasis. The present study found the cutoff level of 0.25 for Ca/Cit. ratio as the highest prognostic value for renal stone formation.

Pro-inflammatory cytokines have been suggested in the pathogenesis of idiopathic nephrotic syndrome (INS), with conflicting results. This study was performed to identify alteration of different serum interleukins (ILs) in children with INS, and their predictive value in response to steroid treatment. Three groups of children (27; steroid-sensitive INS, 21; steroid-resistant INS, and 19 healthy controls) with normal serum C3, negative serologic tests of hepatitis B virus (HBV), hepatitis C virus (HCV), human immune deficiency virus (HIV), and parasitic infections were included in this study. Serum concentrations of IL-1β, IL-2, IL-6, IL-8, IL-13, and IL-18 were measured, using quantitative colorimetric sandwich ELISA kits. Children with secondary nephrotic syndrome, inflammations, systemic disorders, and chronic kidney disease were excluded. The serum concentration of all ILs; except IL-13 and IL-18; was significantly higher in children with INS, compared with the healthy controls. Serum IL-2 had the highest sensitivity of (95.24%) in patients with INS. All of the serum ILs had acceptable accuracy in children with INS, compared with the control group. The serum concentration of IL-1β, IL-6, and IL-8 was significantly higher in children with steroid-sensitive nephrotic syndrome (SSNS), compared with steroid-resistant nephrotic syndrome (SRNS). All of these ILs had acceptable accuracy for the prediction of steroid response in patients with INS. Our findings suggested the pathogenic role of pro-inflammatory cytokines in children with INS, of which IL-1β, IL-6, and IL-8 were accurate biomarkers for the prediction of steroid response in these patients.

Vesicoureteral reflux (VUR) is the most common risk factor of urinary tract infection in children. Currently, diagnosis of VUR depends on invasive imaging studies, with a high radiologic burden. Therefore, different biomarkers have been introduced for the evaluation of these patients. The objective of this study was to identify alteration of urinary interleukins (ILs) excretion in children with primary VUR and renal parenchymal damage, for further clinical application.Urinary concentrations of IL-1α, IL-1β, IL-6, and IL-8 were evaluated in 34 children with VUR (cases) and 36 without VUR (control), during 2018-2019. Urinary concentrations of IL-1, IL-1, IL-6 and IL-8 were measured, using polyclonal antibody ELISA kit, and standardized to urine creatinine (Cr). Patients with infectious or inflammatory disorders, urolithiasis, immune deficiency, acute or chronic kidney disease, and secondary VUR were excluded from the study.Mean age of cases (36.00 ± 27.66) had no significant difference with the control (32.86±29.31) group (p=0.44). The majority of patients had moderate VUR (58.8%), followed by severe (35.3%) and mild (5.9%) grades. Urinary concentration of all ILs/Cr were significantly higher in patients with VUR, compared with those without VUR. There was no significant correlation between urine ILs/Cr with age, gender, serum electrolytes, urine specific gravity, renal ultrasound, laterality or severity of VUR, and DMSA renal scan. All urine ILs/Cr had acceptable sensitivity and accuracy for workup of children with primary VUR.Urine IL-1α, IL-1β, IL-6 and IL-8/Cr were sensitive and accurate additionary screening biomarkers in children with primary VUR.

This is the presentation of a 19-month-old female admitted for recurrent lower urinary tract infection. Renal ultrasound and computed tomography showed a round bladder stone with no associated abnormality. Open cystolithotomy was performed, and a large bladder stone, measured 3.2 x 2 x 3.2 cm, and composed of magnesium ammonium phosphate (struvite) was removed. To the best of our research, this is the youngest patient, involved with a large struvite bladder stone.

A number of therapies are prescribed for the treatment of COVID-19, but none of them have proven efficacy. In this review article, we summarized the pharmacodynamic and pharmacokinetic properties, effect and potential toxicity of Kaletra (combination of lopinavir and ritonavir) among kidney transplant (KTP) patients who have COVID-19. We used a variety of sources by searching through PubMed, Scopus, Embase and Current Content to collect current data about our issue. Articles published in the English language, as full-text manuscripts, and or as abstract form were included in the study. Lopinavir and ritonavir are two structurally related novel protease inhibitors which have antiretroviral properties. They have primarily been used as part of combination therapy for the treatment of HIV, SARS-CoV and MERS-CoV viruses. However, it seems that use of Kaletra is not associated with clinical improvement, or reduces mortality among patients including KTP recipients who have laboratory-confirmed COVID-19. On the other hand, co-administration of Kaletra with medications that are commonly used among KTP recipients including calcineurin inhibitors and mTOR inhibitors has profound drug-drug interactions. Co-administration of Kaletra with these medications could lead to significant and unexpected increase of blood concentrations of both calcineurin and mTOR inhibitors and therefore frequent monitoring of the immunosuppressive drugs concentrations are necessary to optimize immunosuppressive therapy and prevention of toxicity. It is important to note that frequent monitoring of the immunosuppressive drugs concentration is expensive and also not easily available in many countries including our country. According to the above important points, we recommend that use of Kaletra among KTP patients who have laboratory-confirmed COVID-19 should be avoided especially among patients who are still on calcineurin and mTOR inhibitors.

Significant weight gain following renal transplantation is common in adult and pediatric recipients and mostly depends on receiving higher doses of steroids, changes in mood and feelings, as well as their level of physical activities. This study was performed to evaluate body weight and body mass index (BMI) before and after kidney transplantation in children and adolescents. In this cross-sectional study, 71 pediatric renal transplant recipients (42 boys and 29 girls) were included. World Health Organization criteria were used for comparing Z-score BMI for age in our cases. Overweight was defined as Z-score BMI >+1 SD (standard deviation) and obesity as >+2 SD. At the time of transplantation, the mean age was 10.8 ± 3 years (5-16 years) and based on BMIZ-score, the patients were found to be thin (BMIZs +1 SD to +2 SD) in 9.9%, and obese (BMIZs >+2 SD) in 5.6%.The mean follow-up duration after transplantation was 3.57 ± 1.68 years (1-7 years) and at the time of reevaluation after transplant, their mean age was 14.4 years (6-18 years). The mean BMI was 22 ± 5.3 kg/m2, and for BMI grouping, the patients were thin in 7%, normal in 54.9%, overweight in 21.1%, and obese in 17%. Pretransplant thinness (BMIZs +1 SD after transplant. Chronic continuous decrease of glomerular filtration rate (CCD/GFR) was found in 27 cases (38%); 74.1% were male (P = 0.045), hypertriglyceridemia was found in 74.1% (P = 0.023%), hypercholesterolemia in 63% (P = 0.032),and obesity in 18.5% (p = 0.5). The incidence of obesity has tripled after kidney transplantation. It was not a risk factor for graft or patient survival in our experience, whereas pretransplant obesity had some effects on long-term graft outcome.

Objective: This study aims at determining the relationship between prednisolone cumulative dose and linear growth in pre‐pubertal children with idiopathic nephrotic syndrome. Method: This cross‐sectional study was conducted on all children with idiopathic nephrotic syndrome registered to the pediatric nephrology department at the main referral children's hospital in Southwestern Iran. Inclusion criteria included age (males 6 months of use, and the minimum prednisolone cumulative dose of 152 mg/kg. The exclusion criteria were individuals who had entered puberty or had other diseases affecting linear growth. Based on the prednisolone cumulative dose of ≥550 mg/kg (four or more relapses), the children were divided into two groups. All data regarding age, height, and weight at disease onset and the last visit, bone age, and the parents’ height were collected. Secondary variables including mid‐parental target height and predicted adult height were also calculated. Height data were compared between the different rates of relapse. Results: A total of 97 children (68% male) were enrolled. Their post-treatment mean height Z-score was less than that obtained before treatment (−0.584 vs. −0.158; p = 0.001). Subjects with higher prednisolone cumulative doses were found to have more reduction in height Z-score (p = 0.001). Post-treatment height prediction also showed less growth potential compared to pre-treatment target height (p = 0.006). Thirty-three children (34.4%) had four or more relapses, among whom more mean-height Z-score decreases were found compared to those with less-frequent relapses (−0.84 vs. −0.28; p = 0.04). Conclusion: This study showed the negative effect of cumulative dosages of prednisolone on linear growth, which was greater in children with four or more relapses. Resumo: Objetivo: Determinar a relação entre a dose cumulativa de prednisolona e o crescimento linear em crianças pré‐púberes com síndrome nefrótica idiopática. Método: Estudo transversal conduzido em todas as crianças com síndrome nefrótica idiopática registradas no departamento de nefrologia pediátrica no principal hospital infantil para encaminhamento no sudoeste do Irã. Os critérios de inclusão incluíram idade (meninos 6 meses e a dose cumulativa de prednisolona mínima de 152 mg/kg. Os critérios de exclusão foram indivíduos que entraram na puberdade ou tinham outras doenças que afetam o crescimento linear. Com base na dose cumulativa de prednisolona de ≥ 550 mg/kg (≥ 4 recidivas), as crianças foram divididas em dois grupos. Foram coletados todos os dados relacionados a idade, estatura e peso no início da doença e na última visita, idade óssea e estatura dos pais. Também foram calculadas as variáveis secundárias, inclusive estatura‐alvo e estatura adulta prevista. Os dados de estatura foram comparados entre as diferentes taxas de recidivas. Resultados: Foram inscritas 97 crianças (68% do sexo masculino). Seu escore z de estatura média pós‐tratamento foi inferior ao obtido antes do tratamento (−0,584 em comparação com −0,158; p = 0,001). Os indivíduos com maiores doses cumulativas de prednisolona mostraram maior redução no escore z para estatura (p = 0,001). A estatura pós‐tratamento também foi preditiva de menor potencial de crescimento em comparação com a estatura‐alvo pré‐tratamento (p = 0,006); 33 crianças (34,4%) apresentaram ≥ 4 recidivas, entre as quais foram encontradas mais reduções médias no escore z para estatura em comparação com as recidivas menos frequentes (−0,84 em comparação com −0,28; p = 0,04). Conclusão: Este estudo mostrou o efeito negativo das doses cumulativas de prednisolona sobre o crescimento linear, que foi maior em crianças com ≥ 4 recidivas. Keywords: Prednisolone, Linear growth, Children, Nephrotic syndrome, Palavras‐chave: Prednisolona, Crescimento linear, Crianças, Síndrome nefrótica

Managers often believe that collecting more data will continually improve the accuracy of their machine learning models. However, we argue in this paper that when data lose relevance over time, it may be optimal to collect a limited amount of recent data instead of keeping around an infinite supply of older (less relevant) data. In addition, we argue that increasing the stock of data by including older datasets may, in fact, damage the model's accuracy. Expectedly, the model's accuracy improves by increasing the flow of data (defined as data collection rate); however, it requires other tradeoffs in terms of refreshing or retraining machine learning models more frequently. Using these results, we investigate how the business value created by machine learning models scales with data and when the stock of data establishes a sustainable competitive advantage. We argue that data's time-dependency weakens the barrier to entry that the stock of data creates. As a result, a competing firm equipped with a limited (yet sufficient) amount of recent data can develop more accurate models. This result, coupled with the fact that older datasets may deteriorate models' accuracy, suggests that created business value doesn't scale with the stock of available data unless the firm offloads less relevant data from its data repository. Consequently, a firm's growth policy should incorporate a balance between the stock of historical data and the flow of new data. We complement our theoretical results with an experiment. In the experiment, we empirically measure the loss in the accuracy of a next word prediction model trained on datasets from various time periods. Our empirical measurements confirm the economic significance of the value decline over time. For example, 100MB of text data, after seven years, becomes as valuable as 50MB of current data for the next word prediction task., Comment: 43 Pages, 8 Figures, Harvard Business School Working Paper 21-016

Summary Background Hematuria, either macroscopic or microscopic, is an incidental finding of multiple nephrologic or urologic disorders. Disturbances of urine inhibitors or promotors have been suggested as the potential causes of isolated idiopathic hematuria in children and its recurrence. Meanwhile, appropriate treatment of these risk factors might improve secondary asymptomatic or macroscopic hematuria. Objectives The aim of this study was to identify contribution of urinary biochemical abnormalities in children with isolated idiopathic hematuria. Methods About 522 children with isolated hematuria were evaluated in a prospective cross-sectional study. Data such as clinical manifestations, family history, laboratory examinations, structural anomalies, and urine biochemistry were obtained. Patients with nephrolithiasis, nephrocalcinosis, tubulointerstitial disorder, genitourinary abnormality, urinary tract infection, and glomerular disorder were excluded from the study. Variables such as calcium, citrate, oxalate, phosphate, uric acid, cystine, and magnesium were measured in 24-h urine collection. In addition, serum levels of electrolytes, urea, creatinine, parathyroid hormone, and bicarbonate were identified. Results Mean age at diagnosis was 5.9 years, and females outnumbered males (2/1). Of those, 88.5% had microscopic hematuria, and 12.6% experienced episodes of gross hematuria. Abdominal pain was the most common clinical manifestations. Urinary tract infection occurred in 30% of cases. Totally, 94% of patients had single or multiple metabolic abnormalities in 24-h urine excretion including hypocitraturia, 60.7%; hypomagnesuria, 58.2%; hyperuricosuria, 35.8%; hypercalciuria, 33.7%; hyperoxaluria, 33.7%; and cystinuria, 0.76%, respectively. About 8% of cases had mixed urine metabolic disturbances. Most patients had mild hematuria (red blood cell 30/hpf), with no statistical correlation to urine metabolic abnormalities. About 80% of patients had a history of nephrolithiasis in their relatives. Discussion Decreased urinary inhibitor concentration followed by increased stimulator concentration were the most common abnormalities in patients with idiopathic hematuria. Accordingly, measurement of urinary biochemical concentration is highly recommended in children with isolated hematuria. In addition, investigating the therapeutic effect of potassium citrate supplements is highly recommended in these patients to prevent future stone formation and treatment of hematuria. Variables No (%) Female (%) FH of NL (%) Gross hematuria (%) Hypocitraturia 60.7 70.9 (p 66.6 (p = 0.9) 80.1 (p = 0.9) 11 (p = 0.9) Hypomagnesuria 58.2 64.9 (p = 0.008) 71.1 (p = 0.005) 81.3 (p = 0.5) 10.5 (p = 0.98) Hyperuricosuria 35.8 39.6 (p = 0.12) 61.2 (p = 0.77) 84 (p = 0.11) 10.2 (p = 0.47) Hypercalciuria 33.7 28.5 (p = 0.2) 65.8 (p = 0.9) 83.6 (p = 0.26) 10.4 (p = 0.66) Hyperoxaluria 24.9 27.1 (p = 0.3) 70.8 (p = 0.2) 78.5 (p = 0.5) 11.5 (p = 0.68) FH, familial history; NL, nephrolithiasis.

Background The decreasing of mortality rate is one of the most important goals in every intensive care unit (ICU). This study was performed to determine the main causes of admission and mortality rate in our referral pediatric ICU (PICU). Methods In this retrospective study, all patients (age-group, 1 month - 16 years) admitted to the PICU in one year were included and patients with less than a 3h duration of admission, multiple traumas, and post-surgery patients were excluded. Results Among the 688 patients enrolled in the study, 55.6% were male and the mean patient age was 2.7 years. The most common causes of admission were pneumonia (22.9%), bronchiolitis (8.6%), and septicemia (7.9%). The mean duration of hospitalization was 3.3 days and the mortality rate was 16.5%, with a mean age of 2.2 years and 51.8% male. The most common causes of overall mortality were pneumonia (21.6%) and septicemia (16.2%), however, mortality was more common in patients admitted with septicemia (36.6%), liver failure (31.6%), chronic renal failure (28.6%), and meningitis (27.3%). Patients who had undergone intubation before admission, decreased level of consciousness, and prolonged duration of hospitalization were significantly correlated with the mortality (P < 0.05). Conclusions Our results indicate that the respiratory failure and severe infections are the most common causes of admission and mortality in the PICU and very young children are at risk of high incidence of mortality.

Digital technologies have led to the emergence of many platforms in our economy today. In certain platform networks, buyers in one market purchase services from providers in many other markets, whereas other platform networks may comprise local clusters in which buyers primarily purchase services from providers within the same cluster. Consequently, network interconnectivity varies across different industries. We examine how network interconnectivity affects interactions between an incumbent platform serving multiple markets and an entrant platform seeking to enter one of these markets. Our model yields several interesting results. First, even if the entrant can advertise at no cost, it still may not want to make every user in a local market aware of its service, as doing so may trigger a competitive response from the incumbent. Second, having more mobile buyers, which increases interconnectivity between markets, can reduce the incumbent’s incentive to fight and, thus, increase the entrant’s incentive to expand. Third, stronger interconnectivity between markets may or may not make the incumbent more defensible: when advertising is not costly and mobile buyers consume in both their local markets and the markets they visit, a large number of mobile buyers will increase the entrant’s profitability, thereby making it difficult for the incumbent to deter entry. However, when advertising is costly or mobile buyers only consume in the markets they travel to, a large number of mobile buyers will help the incumbent deter entry. When advertising cost is at an intermediate level, the entrant prefers a market with moderate interconnectivity between markets. Fourth, we find that even if advanced targeting technologies can enable the entrant to also advertise to mobile buyers, the entrant may choose not to do so in order to avoid triggering then incumbent’s competitive response. Finally, we find that the presence of network effects is likely to decrease the entrant’s profit. Our results offer managerial implications for platform firms and help understand their performance heterogeneity.

Although the life expectancy of patients with end-stage renal disease (ESRD) has improved in recent years, it is still far below that of the general population. In this retrospective study, we compared the survival of patients with ESRD receiving hemodialysis (HD) versus those on peritoneal dialysis (PD). The study was conducted on patients referred to the HD and PD centers of the Emam Khomini Hospital and the Aboozar Children's Hospital from January 2007 to May 2012 in Ahvaz, Iran. All ESRD patients on maintenance HD or PD for more than two months were included in the study. The survival was estimated by the Kaplan-Meier method and the differences between HD and PD patients were tested by the log-rank test. Overall, 239 patients, 148 patients on HD (61.92%) and 91 patients on continuous ambulatory PD (CAPD) (38.55%) with mean age of 54.1 ± 17 years were enrolled in the study. Regardless of the causes of ESRD and type of renal replacement therapy (RRT), one-, two- and three-year survival of patients was 65%, 51% and 35%, respectively. There was no significant difference between type of RRT in one- (P-value = 0.737), two- (P-value = 0.534) and three- (P-value = 0.867) year survival. There was also no significant difference between diabetic and non-diabetic patients under HD and CAPD in the one-, two- and three-year survival. Although the three-year survival of diabetic patients under CAPD was lower than that of non-diabetic patients (13% vs. 34%), it was not statistically significant (P-value = 0.50). According to the results of the current study, there is no survival advantage of PD during the first years of initiation of dialysis, and the one-, two- and three-year survival of HD and PD patients is also similar.

Incidence of type 1 diabetes mellitus (T1DM) is increasing worldwide. We aimed to study trends in presentation and incidence of childhood diabetes in the last 15years in south-western Iran.During a detailed review of compiled records of the main tertiary children's hospital of southwest of Iran, from January 2000 to December 2009, the following clinical information relevant to diabetes were analysed: admissions, demographic data, clinical and laboratory findings, hospital course, and mortality. Study continued 5years more to find out the real rate of increase. Significant findings with respect to the incidence of DKA, gender and age of subjects were summarized from among these cases. A total of 297 (known and new) cases were enrolled in the 1st (10year) stage of study and 691 new subjects in the 2nd (5year) period to check the trend in the whole 15year study period.In the 1st period; excluding 129 repeated admissions, 297 cases were enrolled for analysis: 223 new and 74 known cases. Among the new cases, 67.3% presented with DKA, without any gender bias. Mortality rate in DKA subjects was 4% with higher risk in the2year group and in girls (boy: girl=1:7; p=0.039). Adding the 2nd study period (total 15years) disclosed a rapid rise of incidence (new cases/5year) as 89, 134 and 691 new diabetes cases for the 1st, 2nd and 3rd 5year period of study respectively. The final annual incidence for15year age group in 2015 was 13.35/100000.The most new cases of T1DM presented with DKA, which is similar to the other developing countries. Such an increasing incidence of DM proposes more attention for periodic retraining of families and health staff to earlier diagnosis and management of new subjects, and to reduce morbidity and mortality rates.

Problem Definition: Farmers face several challenges in agricultural supply chains in emerging economies that contribute to extreme levels of poverty. One common challenge is that farmers only have access to one channel, often an auction, for which to sell their crops. Recently, e-intermediaries have emerged as alternate, technology-driven posted-price channels. We aim to develop insights into the structural drivers of farmer and supply chain profitability in emerging markets and understand the impact of e-intermediaries. Academic/Practical Relevance: In practice, much attention has been given to e-intermediaries and they have often been touted as for-profit social enterprises that improve farmers' welfare. Yet, studies in the operations literature that systematically analyze the impact of e-intermediaries are lacking. Our work fills this gap and answers practical questions regarding the responsible operations of e-intermediaries. Methodology: We develop an analytical model of a supply chain that allows us to study several key features of intermediated supply chains. We complement the model's insights with observations from a numerical study. Results: In the absence of an e-intermediary, auctions cause farmers to either overproduce or underproduce compared to their ideal production levels in a vertically integrated chain. The presence of an e-intermediary with limited market share improves farmers' profits; however, if the e-intermediary grows too large, it negatively impacts both farmers' and supply chain profits. Finally, as the number of farmers increases, farmers' profits approach zero, irrespective of the e-intermediary's presence. Managerial Implications: Our results provide a balanced perspective on the value of e-intermediation, compared to the generally positive views advanced by case studies. For-profit e-intermediaries that also aim to improve farmers' livelihoods cannot blindly operate as pure profit-maximizers, assuming that market forces alone will ensure that farmers benefit. Even when e-intermediation benefits farmers, it is insufficient to mitigate the negative effects of supply fragmentation, suggesting that for farmers, market power is more important than market access.

Background: The accurate diagnosis and management of febrile urinary tract infection (UTI) is a clinical challenge in the absence of specific clinical and laboratory findings in infants and young children. Objectives: The aim of this study was to identify and compare the diagnostic and therapeutic implications of recently introduced cytokines for the diagnosis of acute pyelonephritis (APN). Methods: This multicenter prospective study was performed on 37 (female/male = 6.5:1) children with symptomatic culture-proven APN and 37 (female/male = 1.6/1) age-matched febrile children without UTIs as the control group. Urine samples were obtained before antibiotic treatment in both groups and 3 - 4 days after treatment in the UTI group, and evaluated for interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, tumor necrosis factor-α (TNFα), monocyte chemoattractant protein-1 (MCP-1), and vascular endothelial growth factor (VEGF) using an ELISA immunoassay kit. Results: Mean urinary IL-1α, IL-4, IL-6, and IL-8 concentrations significantly increased in the acute phase of APN compared to the control group, and decreased following antibiotic treatment. Conclusions: We recommend routine urinalysis and urine culture for the diagnosis of children with APN. Urinary IL-4 was a relatively good cytokine for the prediction and treatment-monitoring of children with acute febrile UTI.

Background Nephropathic cystinosis is a rare inherited metabolic disorder leading to progressive renal failure and extra-renal comorbidity. The prognosis relies on early adherence to cysteamine treatment and symptomatic therapies. Developing nations [DiN] experience many challenges for management of cystinosis. The aim of this study was to assess the management characteristics in DiN compared with developed nations [DeN]. Methods A questionnaire was sent between April 2010 and May 2011 to 87 members of the International Pediatric Nephrology Association, in 50 countries. Results A total of 213 patients were included from 41 centres in 30 nations (109 from 17 DiN and 104 from 13 DeN). 7% of DiN patients died at a median age of 5 years whereas no death was observed in DeN. DiN patients were older at the time of diagnosis. In DiN, leukocyte cystine measurement was only available in selected cases for diagnosis but never for continuous monitoring. More patients had reached end-stage renal disease in DiN (53.2 vs. 37.9%, p = 0.03), within a shorter time of evolution (8 vs. 10 yrs., p = 0.0008). The earlier the cysteamine treatment, the better the renal outcome, since the median renal survival increased up to 16.1 [12.5−/] yrs. in patients from DeN treated before the age of 2.5 years of age (p = 0.0001). However, the renal survival was not statistically different between DeN and DiN when patients initiated cysteamine after 2.5 years of age. The number of transplantations and the time from onset of ESRD to transplantation were not different in DeN and DiN. More patients were kept under maintenance dialysis in DiN (26% vs.19%, p = 0.02); 79% of patients from DiN vs. 45% in DeN underwent peritoneal dialysis. Conclusions Major discrepancies between DiN and DeN in the management of nephropathic cystinosis remain a current concern for many patients living in countries with limited financial resources. Electronic supplementary material The online version of this article (doi:10.1186/s12882-017-0633-3) contains supplementary material, which is available to authorized users.

Otukesh H, Hoseini R, Rahimzadeh N, Fereshtehnejad S-M, Simfroosh N, Basiri A, Sharifian M, Hashemi GH, Falahzadeh H, Derakhshan A, Fazel M, Reiesee D, Sayedzadeh A, Vazirian S, Nikibakhsh AA, Moghadam AG, Mohamadzadeh H, Naderi A, Isfahani T, Larijani F, Shorkhi H, Pasha AA, Shahbazian H, Valavi E, Mortazavi F, Gheisari A. Outcome of renal transplantation in children: A multi-center national report from Iran. Pediatr Transplantation 2011: 15: 533–538. © 2011 John Wiley & Sons A/S. Abstract: The outcome of pediatric renal transplantation was previously reported by a single-center study at the year 2006. Therefore, we aimed to evaluate and report the characteristics and outcome of renal pediatric renal transplantation in a multi-center nationwide study. In this nationwide report, medical records of 907 children (≤18 yr) with renal transplantation in eight major pediatric transplant centers of Iran were recorded. These 907 patients received a total of 922 transplants. All children who failed to follow-up were excluded. Rather than baseline characteristics, graft and patient outcomes were considered for survival analysis. For further analysis, they were divided into two groups: patients who had graft survival time more than 10 yr (n = 91) and the ones with graft survival time of equal or less than 10 yr (n = 831). Of 922 recipients, 515 (55.8%) were boys and 407 (44.2%) were girls with the mean age of 13.10 (s.d. = 3.54) yr. DGF and AR were occurred in 10% and 39.5% of the transplanted children, respectively. Transplantation year, dialyzing status before transplantation, DGF, and AR were significant enough to predict graft survival in cox regression model (overall model: p