A CRISPR screen in intestinal epithelial cells identifies novel factors for polarity and apical transport

Epithelial polarization and polarized cargo transport are highly coordinated and interdependent processes. In our search for novel regulators of epithelial polarization and protein secretion, we used a genome-wide CRISPR/Cas9 screen and combined it with an assay based on fluorescence-activated cell sorting (FACS) to measure the secretion of the apical brush-border hydrolase dipeptidyl peptidase 4 (DPP4). In this way, we performed the first CRISPR screen to date in human polarized epithelial cells. Using high-resolution microscopy, we detected polarization defects and mislocalization of DPP4 to late endosomes/lysosomes after knockout of TM9SF4, anoctamin 8, and ARHGAP33, confirming the identification of novel factors for epithelial polarization and apical cargo secretion. Thus, we provide a powerful tool suitable for studying polarization and cargo secretion in epithelial cells. In addition, we provide a dataset that serves as a resource for the study of novel mechanisms for epithelial polarization and polarized transport and facilitates the investigation of novel congenital diseases associated with these processes.

Continuous venovenous hemofiltration with and without dialysis in pediatric patients

Peritoneal dialysis (PD) is often the preferred modality in dialyzing the pediatric patient in acute renal failure. However, PD may be contraindicated in the presence of the acute surgical abdomen, respiratory compromise, or diaphragmatic disruption. The child's size and cardiovascular instability may also render hemodialysis undesirable. The use of continuous arteriovenous hemofiltration (CAVH) has been an option for the acutely ill child but requires arterial and venous access as well as adequate blood pressure to drive the CAVH circuit. Another option is continuous venovenous hemofiltration (CVVH), which obviates the need for arterial access and provides blood flow via an external pump. This article presents a retrospective of 20 acutely ill pediatric patients who received continuous venovenous hemofiltration with and without dialysis (CVVH/D) during the period covering Fall 1992 through Fall 1993 at Children's Hospital in Seattle. The children ranged in age from 1 day to 12 years (mean age 4 years) and weights ranged from 1.7 kg to 76 kg (mean 15.8 kg). Seventeen of the 20 patients were started on CVVH/D due to hemodynamic instability, 1 for PD complications, and 2 for metabolic disorders. Fluid and solute removal were achieved efficiently and metabolic imbalances were easily corrected. Patients received 1-25 days (mean 7.7 days) of CVVH/D.

Peritoneal equilibration test curves and adequacy of dialysis in children on automated peritoneal dialysis

Peritoneal equilibration tests (PETs) and adequacy studies have been performed to guide dialysis prescriptions in adult continuous ambulatory peritoneal dialysis patients, although few studies have been reported in pediatric patients on nightly cycling peritoneal dialysis. We performed 49 PETs in 28 children on automated peritoneal dialysis (mean age, 8.9 years; age range, 0.2 to 19.8 years; mean time on dialysis, 14.1 months) using Dianeal 2.5% dialysate (Baxter Healthcare Corp, McGaw Park, IL) inflow volumes of 1,200 mL/m2 (approximately 40 mL/kg), and standard technique. Mean 4-hour dialysate/plasma creatinine was 0.73 +/- 0.12 (range, 0.45 to 1.03). Mean 4-hour dialysate glucose/initial dialysate glucose was 0.28 +/- 0.10 (range, 0.06 to 0.50). Eighty percent of these PETs fell into the high average/high solute transport categories proposed by Twardowski, based on adult PETs. Twenty-four-hour dialysate collections were analyzed in 28 patients for protein loss and glucose absorption, as well as for calculation of weekly Kt/V. Mean weekly Kt/V was 1.94 +/- 0.94 (range, 0.63 to 5.10). Mean dialytic creatinine clearance calculated from the 4-hour dwell was 5.6 +/- 1.0 mL/min/1.73 m2 (56 L/wk/1.73 m2). Mean daily protein loss was 0.20 +/- 0.13 g/kg/d (range, 0.2 to 9.1 g/d) and glucose absorption was 3.49 +/- 2.24 g/kg/d (range, 17 to 196 g/d). Our results show higher solute diffusion rates in children compared with the published adult PET results (P = 0.0013 and P < 0.0001 for 4-hour creatinine and glucose results, respectively), with trends toward more rapid solute transport in younger compared with older children.(ABSTRACT TRUNCATED AT 250 WORDS)

Pediatric case study: hemolytic uremic syndrome

The nursing interventions necessary to care for this critically ill child were professionally challenging. Meeting the psychosocial, educational, and supportive needs of the family during this period of uncertainty, as well as, providing the dialysis therapy and support for this fragile child demonstrated the unique contributions of professional nursing. All outcomes were met, but the patient's extremely poor myocardial function made dialysis treatments and volume control difficult. The use of CVVHD was instrumental to providing dialysis in a safe, effective manner. The nursing care for S.B.K. and her family was physically and emotionally draining, but seeing her neurological status return was the great reward for all of our efforts.

Benefits of a mainstreamed summer camp experience for teens with ESRD

This is a report on a pilot project integrating children with end stage renal disease (ESRD) with well children for a summer camp experience. As the teen with ESRD prepares to enter the work force and college, he/she will have to adapt to a variety of situations that will not adapt to his/her unique medical condition. These issues motivated a pilot project in which 9 ESRD children were mainstreamed into a 2 week, YMCA summer camp experience. Pre and post questionnaires were developed and distributed to the camper, family, and the cabin counselor along with interviews to assess the value of the experience. All the children left camp more independent and knowledgeable about their self-care. The results of this pilot project indicate that children with ESRD can adapt to their environment and increase independence, self-care and self-esteem through supervised mainstreamed experiences.