The Japanese Pediatric Continuous Renal Replacement Therapy (jpCRRT) Registry: Study Protocol.

BACKGROUND: The use of continuous renal replacement therapy (CRRT) in critically ill children is rapidly increasing, but the standard of care has not yet been established and prognosis remains poor. To develop optimal CRRT strategies, we launched a research project generating the Japanese Pediatric CRRT registry, a multicenter registry of CRRT in Japanese pediatric intensive care units (PICUs), to investigate the actual status of CRRT in recent years in PICUs, where data are lacking. METHODS: This manuscript presents a protocol for planning a multicenter prospective registry. As of April 2023, 15 Japanese PICUs are voluntarily participating. Patients enrolled are those <16 years of age who enter the PICUs of the collaborating institutions, require CRRT, and have the guardians' consent. CRRT is defined as anticipated to be required for >24 hours, and CRRT connected to extracorporeal membrane oxygenation is also included. The registry is an online registry system managed by the University Hospital Medical Information Network. The primary outcomes are Pediatric Cerebral Performance Category Scale at PICU discharge and 6 months post-discharge (deaths included), persistent need for dialysis, and PICU readmission within 6 months. The secondary outcomes are adverse events during and immediately after CRRT initiation, and initial circuit life span. CONCLUSIONS: This project will examine the differences in outcomes of CRRT in PICUs in specific patient and treatment groups and will be used to design future interventional studies. We will also aim to establish a platform for a multicenter registry study in Japanese PICUs, considering the current lack of such a platform.

Comprehensive Detection of Candidate Pathogens in the Lower Respiratory Tract of Pediatric Patients With Unexpected Cardiopulmonary Deterioration Using Next-Generation Sequencing.

OBJECTIVES: Next-generation sequencing has been applied to the investigation of microorganisms in several clinical settings. We investigated the infectious etiologies in respiratory specimens from pediatric patients with unexpected cardiopulmonary deterioration using next-generation sequencing. DESIGN: Retrospective, single-center, observational study. SETTING: Tertiary care, a children's hospital. SUBJECTS: The study enrolled a total of 16 pediatric patients with unexpected cardiopulmonary deterioration who were admitted to the PICU. Ten bronchoalveolar lavage fluid and six transtracheal aspirate samples were analyzed. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: RNA libraries were prepared from specimens and analyzed using next-generation sequencing. One or more bacterial/viral pathogens were detected in the bronchoalveolar lavage fluid or transtracheal aspirate specimens from 10 patients. Bacterial and viral coinfection was considered in four cases. Compared with the conventional culture and viral antigen test results, an additional six bacterial and four viral pathogens were identified by next-generation sequencing. Conversely, among 18 pathogens identified by the conventional methods, nine pathogens were detected by next-generation sequencing. Candidate pathogens (e.g., coxsackievirus A6 and Chlamydia trachomatis) were detected by next-generation sequencing in four of 10 patients in whom no causative pathogen had been identified by conventional methods. CONCLUSIONS: Our results suggest that viral and bacterial infections are common triggers in unexpected cardiopulmonary deterioration in pediatric patients. Next-generation sequencing has the potential to contribute to clarification of the etiology of pediatric critical illness.

Mathematical modeling analysis of hepatic uric acid disposition using human sandwich-cultured hepatocytes.

Uric acid is biosynthesized from purine by xanthine oxidase (XO) mainly in the liver and is excreted into urine and feces. Although several transporters responsible for renal and intestinal handling of uric acid have been reported, information on hepatic transporters is limited. In the present study, we studied quantitative contribution of transporters for hepatic handling of uric acid by mathematical modeling analysis in human sandwich-cultured hepatocytes (hSCH). Stable isotope-labeled hypoxanthine, hypoxanthine-13C2,15N (HX), was incubated with hSCH and formed 13C2,15N-labeled xanthine (XA) and uric acid (UA) were measured by LC-MS/MS time dependently. Rate constants for metabolism and efflux and uptake transport across sinusoidal and bile canalicular membranes of HX, XA and UA were estimated in the presence of inhibitors of XO and uric acid transporters. An XO inhibitor allopurinol significantly decreased metabolisms of HX and XA. Efflux into bile canalicular lumen was negligible and sinusoidal efflux was considered main efflux pathway of formed UA. Transporter inhibition study highlighted that GLUT9 strongly and MRP4 intermediately contribute to the sinusoidal efflux of UA with minor contribution of NPT1/4. Modeling analysis developed in the present study should be useful for quantitative prediction of uric acid disposition in liver.

Metagenomic analysis using next-generation sequencing of pathogens in bronchoalveolar lavage fluid from pediatric patients with respiratory failure.

Next-generation sequencing (NGS) has been applied in the field of infectious diseases. Bronchoalveolar lavage fluid (BALF) is considered a sterile type of specimen that is suitable for detecting pathogens of respiratory infections. The aim of this study was to comprehensively identify causative pathogens using NGS in BALF samples from immunocompetent pediatric patients with respiratory failure. Ten patients hospitalized with respiratory failure were included. BALF samples obtained in the acute phase were used to prepare DNA- and RNA-sequencing libraries. The libraries were sequenced on MiSeq, and the sequence data were analyzed using metagenome analysis tools. A mean of 2,041,216 total reads were sequenced for each library. Significant bacterial or viral sequencing reads were detected in eight of the 10 patients. Furthermore, candidate pathogens were detected in three patients in whom etiologic agents were not identified by conventional methods. The complete genome of enterovirus D68 was identified in two patients, and phylogenetic analysis suggested that both strains belong to subclade B3, which is an epidemic strain that has spread worldwide in recent years. Our results suggest that NGS can be applied for comprehensive molecular diagnostics as well as surveillance of pathogens in BALF from patients with respiratory infection.

Cardiac arrest caused by rapidly increasing ascites in a patient with TAFRO syndrome: a case report.

Case: Thrombocytopenia, anasarca, fever, renal insufficiency, and organomegaly (TAFRO) syndrome is a newly defined systemic inflammatory disorder with gradual progression of symptoms. A 59-year-old man with fever and ascites of unknown cause developed sudden-onset shock and respiratory failure in the general ward. Cardiac arrest immediately followed. Although he was resuscitated, frequent administration of adrenaline was required to maintain his blood pressure. His circulation was most effectively stabilized by drainage of fluid from his distended abdomen. The volume of discharged ascites reached 4,000 mL at that time, and several liters continued to be discharged for >1 month. The diagnosis of TAFRO syndrome was based on the clinical features and laboratory and histological findings. Outcome: The ascites volume and concentrations of inflammatory parameters decreased with treatment using several immunosuppressive agents. Conclusion: The newly defined TAFRO syndrome may be life-threatening. Patients should be monitored for progression to shock and cardiac arrest, especially those with rapidly increasing ascites.

Mathematical modeling of the in vitro hepatic disposition of mycophenolic acid and its glucuronide in sandwich-cultured human hepatocytes.

In recent years, it has become increasingly important to test the safety of circulating metabolites of novel drugs as part of drug discovery and development programs. Accordingly, it is essential to develop suitable methods for identifying the major metabolites and their disposition in animal species and in humans. Mycophenolic acid (MPA), a selective inosine-5'-monophosphate dehydrogenase (IMPDH) inhibitor, is metabolized by glucuronidation and enterohepatic circulation of MPA-glucuronides is an important factor in the continuous systemic exposure of MPA. In humans, about 90% of the administered MPA dose is finally excreted as MPA phenyl-glucuronide (MPAG) in urine. Notably, the plasma concentration of MPAG is much higher than that of MPA. These factors suggest that, after its formation in hepatocytes, MPAG is excreted into bile and is also transported across the basolateral membrane to enter the circulation. In the present study, we performed metabolic/hepatobiliary transport studies of MPA and MPAG using sandwich-cultured human hepatocytes (SCHH) and constructed mathematical models of their hepatic disposition. We also performed vesicular transport studies to identify which human multidrug resistance-associated proteins (MRPs) are involved in the transport of MPAG from hepatocytes. MPAG was a preferred substrate for the biliary excretion transporter MRP2 and the hepatic basolateral transporters MRP3 and MRP4 in conventional and metabolic/hepatobiliary transport studies using SCHH and vesicular transport studies using human MRP-expressing membrane vesicles. The resulting mathematical model suggested that the basolateral transport plays an important role in the hepatic disposition of MPAG formed in hepatocytes. Our findings suggest that mathematical modeling of metabolic/hepatobiliary transport studies using SCH will provide useful information for determining the fate of metabolites formed in hepatocytes.

The role of inter-segmental differences in P-glycoprotein expression and activity along the rat small intestine in causing the double-peak phenomenon of substrate plasma concentration.

  Conflicting results have been reported on segmental differences in expression of P-glycoprotein (P-gp) along the small intestine of animals and humans. In this study, we investigated P-gp mRNA and protein levels within each of nine segments of rat small intestine. In addition, P-gp activity in each segment was evaluated in terms of permeability of rhodamine123 (Rho123), a typical P-gp substrate, using the serial intestinal non-everted sac method. The P-gp mRNA levels tended to increase from the duodenum to the ileum, with peaks in the upper and lower ileum, while P-gp protein level reached its maximum in the middle ileum. The activity of P-gp was also the highest in the middle ileum, and was highly correlated with P-gp protein level. The double-peaked plasma concentration profile that was observed following oral administration of Rho123 to rats could be well reproduced by an intestinal compartmental kinetic model incorporating inter-segmental differences of absorption and excretion rate constants. Our results suggest that the heterogeneous distribution of P-gp along the small intestine plays a key role in causing the double-peak of plasma concentration of P-gp substrates following oral administration to rats.

Developmental changes of brain distribution and localization of oseltamivir and its active metabolite Ro 64-0802 in rats.

Oseltamivir, a prodrug of the neuraminidase inhibitor [3R, 4R, 5S]-4-Acetamide-5-amino-3-(1-ethylpropyl)-1-cyclohexene-1-carboxylate phosphate (Ro 64-0802), is widely used for treatment of influenza infections in Japan, but may be associated with mental instability and suicidal tendencies as a rare side effect, especially in infants and young patients. We examined developmental changes in the brain distribution of oseltamivir and Ro 64-0802, and in the expression of P-glycoprotein (P-gp) at the blood-brain barrier (BBB) in rats by 8 weeks. Brain concentration and Kp(,app,brain) (brain-to-plasma concentration ratio) of oseltamivir were highest in 2-week-old rats (1.45 µg/g brain and 0.14, respectively), and were negatively correlated with both age and P-gp expression at the BBB. In contrast, brain concentration and Kp(,app,brain) of Ro 64-0802 after oral gavage of oseltamivir were lowest in 2-week-old rats (0.02 µg/g brain and 0.02), and increased with age. Mass imaging analysis revealed that both compounds were distributed homogenously in brain cross-sections, including the hippocampus. From these results, it was estimated that oseltamivir concentration throughout the brain cross-sections was 70-fold and 0.9-fold higher than that of Ro 64-0802 in 2-week-old and 8-week-old rats, respectively. Such developmental changes of prodrug/drug concentration ratio, if they also occur in humans, may provide a rational basis for the putative central nervous system (CNS) side effects in young patients.

Effect of knockdown of ezrin, radixin, and moesin on P-glycoprotein function in HepG2 cells.

Ezrin, radixin, and moesin (ERM) proteins regulate functional expression of certain transporters, but little is known about their effect on P-glycoprotein (P-gp). Here, we investigated the influence of ERM proteins on the expression and activity of P-gp at the transcriptional, translational, and posttranslational levels, using HepG2 as a model cell line. Knockdown of ezrin with RNA interference decreased the level of P-gp messenger RNA. On the contrary, knockdown of radixin caused a decrease of the P-gp gene product at the cell surface, but not in whole cell lysate. Furthermore, a significant increase in accumulation of rhodamine123, a typical P-gp substrate, was observed in radixin knockdown cells, compared with control cells. Knockdown of moesin did not influence the expression or function of P-gp. These results indicate that ezrin influences the expression of P-gp at the translational level, whereas radixin is involved in membrane localization of P-gp in HepG2 cells.

Enhancement of drug solubility and absorption by copolymers of 2-methacryloyloxyethyl phosphorylcholine and n-butyl methacrylate.

Poly[2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate]s (PMBs) are water-soluble solid copolymers of 2-methacryloyloxyethyl phosphorylcholine (MPC) and n-butyl methacrylate with a molecular weight of 30,000 (PMB50T) or 100,000 (PMB100T). Here, we characterized the solubilizing properties of PMBs using miconazole (MCZ), vidarabine (Ara-A) and griseofulvin (GRF), which are class 2, 3 and 4 compounds, respectively, in the Biopharmaceutics Classification System (BCS). Moreover, we evaluated the enhancement of gastric absorption of GRF dissolved in PMB solutions and the toxicity of PMBs in rats. PMB50T solution dramatically increased the solubility of GRF and MCZ compared with Ara-A, and these drugs became more soluble as the concentration of PMB50T was increased. The solubility of GRF in 10% PMB solutions was higher than with any other tested aqueous solubilizer. When a solution of GRF (20 mg/10 mL/kg) in 10% PMB was orally administered to rats, GRF absorption was greatly increased compared with that following administration of a suspension in water or Gelucire. After repeated oral administration of PMBs once daily for 14 successive days, no organ lesions or changes in biochemical parameters were observed. Thus, the polymers are expected to be useful and safe solubilizers and oral absorption enhancers for poorly soluble lipophilic drugs.

Oseltamivir (tamiflu) is a substrate of peptide transporter 1.

Oseltamivir, an ester-type prodrug of the neuraminidase inhibitor [3R,4R,5S]-4-acetamido-5-amino-3-(1-ethylpropoxy)-1-cyclohexene-1-carboxylate phosphate (Ro 64-0802), has been developed for the treatment of A and B strains of the influenza virus but has neuropsychiatric and other side effects. In this study, we characterized the transport across intestinal epithelial cells and the absorption of oseltamivir in rats. Uptake by Caco-2 cells (human carcinoma cell line) and HeLa cells transfected with peptide transporter 1 (HeLa/PEPT1) was time- and temperature-dependent and was inhibited by typical PEPT1 inhibitors such as glycyl-sarcosine (Gly-Sar). The uptake by Caco-2 cells and HeLa/PEPT1 was saturable, with similar K(m) values. Oseltamivir absorption in adult rats was greatly reduced by simultaneous administration of milk, casein, or Gly-Sar. Furthermore, the plasma and brain concentrations of oseltamivir were higher in fasting than in nonfasting rats after oral administration. These results suggest that oseltamivir is a substrate of PEPT1 and that PEPT1 is involved in its intestinal absorption.