Hyperchloremia and association with acute kidney injury in critically ill children.

BACKGROUND: Hyperchloremia has been associated with acute kidney injury (AKI) in critically ill adult patients. Data is limited in pediatric patients. Our study sought to determine if an association exists between hyperchloremia and AKI in pediatric patients admitted to the intensive care unit (PICU). METHODS: This is a single-center retrospective cohort study of pediatric patients admitted to the PICU for greater than 24 h and who received intravenous fluids. Patients were excluded if they had a diagnosis of kidney disease or required kidney replacement therapy (KRT) within 6 h of admission. Exposures were hyperchloremia (serum chloride ≥ 110 mmol/L) within the first 7 days of PICU admission. The primary outcome was the development of AKI using the Kidney Disease Improving Global Outcomes (KDIGO) criteria. Secondary outcomes included time on mechanical ventilation, new KRT, PICU length of stay, and mortality. Outcomes were analyzed using multivariate logistic regression. RESULTS: There were 407 patients included in the study, 209 in the hyperchloremic group and 198 in the non-hyperchloremic group. Univariate analysis demonstrated 108 (51.7%) patients in the hyperchloremic group vs. 54 (27.3%) in the non-hyperchloremic group (p = < .001) with AKI. On multivariate analysis, the odds ratio of AKI with hyperchloremia was 2.24 (95% CI 1.39-3.61) (p = .001). Hyperchloremia was not associated with increased odds of mortality, need for KRT, time on mechanical ventilation, or length of stay. CONCLUSION: Hyperchloremia was associated with AKI in critically ill pediatric patients. Further pediatric clinical trials are needed to determine the benefit of a chloride restrictive vs. liberal fluid strategy. A higher resolution version of the Graphical abstract is available as Supplementary information.

Remote triage in paediatric critical care: A Canadian provincial-wide cohort study.

OBJECTIVE: To describe remote triage of 'potentially' critically ill or injured children in a western Canadian province and to examine the associated factors with 'missings' in vital sign items recorded in centralized telephone triage consultations. METHODS: This is a provincial-wide prospective cohort study. We included all children under 17 years of age consulted through the central transport coordination centres in Alberta from June 2016 to July 2017. We labeled a value as 'missing' when the actual value was not identified in the audio records. RESULTS: In total, 429 cases were included in this study. The median duration of triage calls was 6.8 minutes. Although the patients' demographics and primary diagnoses were similar, backgrounds of the referring physicians and hospitals were significantly different between the two cohorts (i.e., patients referred to Calgary versus Edmonton). The proportion of 'missings' among the vital sign items varied significantly, in which capillary refilling time (60%), pupils (86%), Glasgow Coma Scale (GCS) (79%), and level of respiratory effort (50%) were not well recorded, whereas heart rate (proportion of 'missings': 12%), SpO2 (20%), and respiratory rate (26%) were recorded reasonably well. The lower proportion of 'missings' was observed in older aged patients for several vital sign items including systolic blood pressure and GCS. CONCLUSIONS: The proportion of missing vital signs recorded varied significantly. The 'missings' could be associated with referring physician's background and patients' demographics such as 'age' that should be considered for the improvement of triage quality in the future.

Telemedicine-guided thoracentesis of tension pneumothorax in a term newborn.

We describe a case of a term female infant born in a rural community hospital and who developed a left-sided spontaneous tension pneumothorax shortly after birth. We used telemedicine to guide the family physician and healthcare team at the referring hospital to perform a life-saving thoracentesis using an intravenous cannula. The cannula was kept in place to drain the persistent pneumothorax during transportation to the pediatric intensive care unit at the tertiary hospital.

Hyaluronan-CD44 interaction with protein kinase C(epsilon) promotes oncogenic signaling by the stem cell marker Nanog and the Production of microRNA-21, leading to down-regulation of the tumor suppressor protein PDCD4, anti-apoptosis, and chemotherapy resistance in breast tumor cells.

Multidrug resistance and disease relapse is a challenging clinical problem in the treatment of breast cancer. In this study, we investigated the hyaluronan (HA)-induced interaction between CD44 (a primary HA receptor) and protein kinase Cepsilon (PKCepsilon), which regulates a number of human breast tumor cell functions. Our results indicate that HA binding to CD44 promotes PKCepsilon activation, which, in turn, increases the phosphorylation of the stem cell marker, Nanog, in the breast tumor cell line MCF-7. Phosphorylated Nanog is then translocated from the cytosol to the nucleus and becomes associated with RNase III DROSHA and the RNA helicase p68. This process leads to microRNA-21 (miR-21) production and a tumor suppressor protein (e.g. PDCD4 (program cell death 4)) reduction. All of these events contribute to up-regulation of inhibitors of apoptosis proteins (IAPs) and MDR1 (multidrug-resistant protein), resulting in anti-apoptosis and chemotherapy resistance. Transfection of MCF-7 cells with PKCepsilon or Nanog-specific small interfering RNAs effectively blocks HA-mediated PKCepsilon-Nanog signaling events, abrogates miR-21 production, and increases PDCD4 expression/eIF4A binding. Subsequently, this PKCepsilon-Nanog signaling inhibition causes IAP/MDR1 down-regulation, apoptosis, and chemosensitivity. To further evaluate the role of miR-21 in oncogenesis and chemoresistance, MCF-7 cells were also transfected with a specific anti-miR-21 inhibitor in order to silence miR-21 expression and inhibit its target functions. Our results indicate that anti-miR-21 inhibitor not only enhances PDCD4 expression/eIF4A binding but also blocks HA-CD44-mediated tumor cell behaviors. Thus, this newly discovered HA-CD44 signaling pathway should provide important drug targets for sensitizing tumor cell apoptosis and overcoming chemotherapy resistance in breast cancer cells.

Hyaluronan-CD44 interaction stimulates keratinocyte differentiation, lamellar body formation/secretion, and permeability barrier homeostasis.

In this study we investigated whether hyaluronan (HA)-CD44 interaction influences epidermal structure and function. Our data show that CD44 deficiency is accompanied by reduction in HA staining in CD44 knockout (k/o) mouse skin leading to a marked thinning of epidermis versus wild-type mouse skin. A significant delay in the early barrier recovery (following acute barrier disruption) occurs in CD44 k/o versus wild-type mouse skin. To assess the basis for these alterations in CD44 k/o mouse epidermis, we determined that differentiation markers are greatly reduced in the epidermis of CD44 k/o versus wild-type mice, while conversely HA binding to CD44 triggers differentiation in cultured human keratinocytes. CD44 downregulation (using CD44 small interfering RNAs) also inhibits HA-mediated keratinocyte differentiation. Slower barrier recovery in CD44 k/o mice could be further attributed to reduced lamellar body formation, loss of apical polarization of LB secretion, and downregulation of cholesterol synthesis. Accordingly, HA-CD44 binding stimulates both LB formation and secretion. Together, these observations demonstrate new roles for HA-CD44 interaction in regulating both epidermal differentiation and lipid synthesis/secretion, which in turn influence permeability barrier homeostasis. HA-CD44 signaling could comprise a novel approach to treat skin disorders characterized by abnormalities in differentiation, lipid synthesis, and/or barrier function.

Epidemiologic, socioeconomic, and clinical factors associated with severity of respiratory syncytial virus infection in previously healthy infants.

We prospectively quantified disease severity associated with epidemiologic and socioeconomic parameters as well as the clinical factors in 195 previously healthy infants with confirmed respiratory syncytial virus (RSV) infection. Infants were enrolled into three subgroups according to disease severity: outpatients (82 patients), inpatients (100 patients), and intensive care unit patients (13 patients). Epidemiologic parameters such as gestational age, birth weight, chronologic age at presentation, and gender as well as socioeconomic factors such as ethnic origin, family history of asthma, exposure to cigarette smoke, number of family members, presence of pets at home, breast-feeding, and day-care attendance were not found to predict the severity of RSV illness in previously healthy infants. Our results emphasize the complexity of predicting disease severity in previously healthy infants with RSV infection and suggest that other parameters such as host genetic background might explain the clinical variability.

Pediatric refractory partial status epilepticus responsive to topiramate.

Topiramate was safely administered to two young children with refractory partial status epilepticus via nasogastric tube in rapid titration up to a very high total daily dose. An excellent clinical response occurred in both cases. Reaching high daily doses of topiramate within days allowed for safe discontinuation of other antiepileptic drugs in both patients. Given the high efficacy of rapidly titrated topiramate in our patients, this medication may be useful in some cases of pediatric refractory partial status epilepticus. However, more clinical studies on this therapeutic approach are needed to establish the precise role of topiramate in status epilepticus in children.

Muscle glycogen depletion and increased oxidative phosphorylation following status epilepticus.

We describe complete glycogen depletion and increased respiratory chain enzyme activity in a muscle biopsy obtained prior to the demise of a patient in multiorgan failure following status epilepticus. These findings validate the theoretical basis of muscle energy turnover during status epilepticus: the increased demand for energy leads to complete depletion of glycogen reserves. The attempt to preserve adenosine triphosphate requirements results in increased activity of respiratory chain enzymes.

Neonatal acute appendicitis: a proposed algorithm for timely diagnosis.

BACKGROUND: Neonatal appendicitis (NA) is a rare disease with a high mortality. The diagnosis has never been reported preoperatively and is notoriously difficult to make. METHODS: Charts since 1995 were retrospectively reviewed for discharge or death diagnoses of appendicitis in neonates younger than 28 days. We report 3 cases of NA seen at our institution during this period. RESULTS: All 3 infants were previously well, born at term, and presented with signs consistent with abdominal sepsis. The first 2 diagnoses were not made until autopsy. The third case survived after having an urgent computed tomographic scan, exploratory laparotomy, and appendectomy. DISCUSSION: The literature summarizing common presenting features of NA is reviewed. We present an algorithm to guide the workup of these neonates to facilitate earlier diagnosis and potentially improve outcomes.

Hyaluronan-CD44 interaction activates stem cell marker Nanog, Stat-3-mediated MDR1 gene expression, and ankyrin-regulated multidrug efflux in breast and ovarian tumor cells.

Hyaluronan (HA) is a major glycosaminoglycan in the extracellular matrix whose expression is tightly linked to multidrug resistance and tumor progression. In this study we investigated HA-induced interaction between CD44 (a HA receptor) and Nanog (an embryonic stem cell transcription factor) in both human breast tumor cells (MCF-7 cells) and human ovarian tumor cells (SK-OV-3.ipl cells). Using a specific primer pair to amplify Nanog by reverse transcriptase-PCR, we detected the expression of Nanog transcript in both tumor cell lines. In addition, our results reveal that HA binding to these tumor cells promotes Nanog protein association with CD44 followed by Nanog activation and the expression of pluripotent stem cell regulators (e.g. Rex1 and Sox2). Nanog also forms a complex with the "signal transducer and activator of transcription protein 3" (Stat-3) in the nucleus leading to Stat-3-specific transcriptional activation and multidrug transporter, MDR1 (P-glycoprotein) gene expression. Furthermore, we observed that HA-CD44 interaction induces ankyrin (a cytoskeletal protein) binding to MDR1 resulting in the efflux of chemotherapeutic drugs (e.g. doxorubicin and paclitaxel (Taxol)) and chemoresistance in these tumor cells. Overexpression of Nanog by transfecting tumor cells with Nanog cDNA stimulates Stat-3 transcriptional activation, MDR1 overexpression, and multidrug resistance. Down regulation of Nanog signaling or ankyrin function (by transfecting tumor cells with Nanog small interfering RNA or ankyrin repeat domain cDNA) not only blocks HA/CD44-mediated tumor cell behaviors but also enhances chemosensitivity. Taken together, these findings suggest that targeting HA/CD44-mediated Nanog-Stat-3 signaling pathways and ankyrin/cytoskeleton function may represent a novel approach to overcome chemotherapy resistance in some breast and ovarian tumor cells displaying stem cell marker properties during tumor progression.

Heregulin-mediated ErbB2-ERK signaling activates hyaluronan synthases leading to CD44-dependent ovarian tumor cell growth and migration.

Heregulin (HRG)-induced cell responses are mediated by the ErbB family of tyrosine kinase receptors. In this study we have investigated HRG activation of ErbB2, extracellular signal-regulated kinase (ERK) signaling, and their role in regulating hyaluronan synthase (HAS) activity in human ovarian tumor cells (SK-OV-3.ipl cells). Immunological and biochemical analyses indicate that ErbB2, ErbB3, and ErbB4 are all expressed in SK-OV-3.ipl cells and that ErbB4 (but not ErbB3) is physically linked to ErbB2 following HRG stimulation. Furthermore, our data indicate that the HRG-induced ErbB2.ErbB4 complexes stimulate ErbB2 tyrosine kinase, which induces both ERK phosphorylation and kinase activity. The activated ERK then increases the phosphorylation of HAS1, HAS2, and HAS3. Consequently, all three HAS isozymes are activated resulting in hyaluronan (HA) production. Because HRG-mediated HAS isozyme phosphorylation/activation can be effectively blocked by either AG825 (an ErbB2 inhibitor) or thiazolidinedione compound (an ERK blocker), we conclude that ErbB2-ERK signaling and HAS isozyme phosphorylation/HA production are functionally coupled in SK-OV-3.ipl cells. HRG also promotes HA- and CD44-dependent oncogenic events (e.g. CD44-Cdc42 association, p21-activated kinase 1 activation, and p21-activated kinase 1-filamin complex formation) and tumor cell-specific behaviors in an ErbB2-ERK signaling-dependent manner. Finally, we have found that the down-regulation of HAS isozyme expression (by transfecting cells with HAS1/HAS2/HAS3-specific small interfering RNAs) not only inhibits HRG-mediated HAS phosphorylation/activation and HA production but also impairs CD44-specific Cdc42-PAK1/filamin signaling, cytoskeleton activation and tumor cell behaviors. Taken together, these findings clearly indicate that HRG activation of ErbB2-ERK signaling modulates HAS phosphorylation/activation and HA production leading to CD44-mediated oncogenic events and ovarian cancer progression.

Hyaluronan-CD44 interaction with neural Wiskott-Aldrich syndrome protein (N-WASP) promotes actin polymerization and ErbB2 activation leading to beta-catenin nuclear translocation, transcriptional up-regulation, and cell migration in ovarian tumor cells.

In this study we have investigated the interaction of hyaluronan (HA) and CD44 with the neuronal Wiskott-Aldrich syndrome protein (N-WASP) in regulating actin polymerization and ErbB2/beta-catenin signaling in human ovarian tumor cells (SK-OV-3.ipl cells). Biochemical and immunological analyses indicate that N-WASP is expressed in SK-OV-3.ipl cells and that the binding of HA stimulates N-WASP association with CD44 and Arp2/Arp3 leading to filamentous actin formation and ovarian tumor cell migration. In addition, HA binding promotes CD44-N-WASP association with ErbB2 and activates ErbB2 kinase activity that in turn increases phosphorylation of the cytoskeletal protein, beta-catenin. Subsequently, phosphorylated beta-catenin is transported into the nucleus leading to beta-catenin-mediated TCF/LEF-transcriptional co-activation. Because HA-induced beta-catenin phosphorylation, nuclear translocation, and TCF/LEF transcriptional activation is effectively blocked by the ErbB2 inhibitor, AG825, we conclude that HA/CD44-N-WASP-associated ErbB2 activation is required for beta-catenin-mediated signaling events. Transfection of SK-OV-3.ipl cells with N-WASP-VCA (verpolin homology, cofilin homology, and acidic domain) fragment cDNA not only blocks HA/CD44-induced N-WASP-Arp2/3 complex formation but also inhibits actin polymerization/F-actin assembly and tumor cell migration. Overexpression of the N-WASP-VCA domain also significantly reduces HA-induced ErbB2 recruitment to CD44, diminishes beta-catenin phosphorylation/nuclear translocation, and abrogates TCF/LEF-specific transcriptional co-activation by beta-catenin. Taken together, our findings strongly suggest that N-WASP plays a pivotal role in regulating HA-mediated CD44-ErbB2 interaction, beta-catenin signaling, and actin cytoskeleton functions that are required for tumor-specific behaviors and ovarian cancer progression.

Hyaluronan-CD44 interaction stimulates Rac1 signaling and PKN gamma kinase activation leading to cytoskeleton function and cell migration in astrocytes.

Both hyaluronan [HA, the major glycosaminoglycans in the extracellular matrix (ECM)] and CD44 (a primary HA receptor) are associated with astrocyte activation and tissue repair following central nervous system (CNS) injury. In this study we investigated the question of whether HA-CD44 interaction influences astrocyte signaling and migration. Our data indicated that HA binding to the cultured astrocytes stimulated Rac1 signaling and cytoskeleton-mediated migration. To determine the cellular and molecular basis of these events, we focused on PKN gamma, a Rac1-activated serine/threonine kinase in astrocytes. We determined that HA binding to astrocytes stimulated Rac1-dependent PKN gamma kinase activity which, in turn, up-regulated the phosphorylation of the cytoskeletal protein, cortactin, and attenuated the ability of cortactin to cross-link F-actin. Further analyses indicated that the N-terminal antiparallel coiled-coil (ACC) domains of PKN gamma interacted with Rac1, and transfection of astrocytes with PKN gamma-ACCcDNA inhibited PKN gamma activity. Over-expression of the PKN gamma-ACC domain also functions as a dominant-negative mutant to block HA/CD44-mediated PKN gamma activation of cortactin and astrocyte migration. Taken together, these findings strongly suggest that hyaluronan/CD44 interaction with Rac1-PKN gamma plays a pivotal role in cytoskeleton activation and astrocyte migration. These newly discovered HA/CD44-induced astrocyte function may provide important insight into novel therapeutic treatments for tissue repair following CNS injury.

Hyaluronan-CD44 interaction with leukemia-associated RhoGEF and epidermal growth factor receptor promotes Rho/Ras co-activation, phospholipase C epsilon-Ca2+ signaling, and cytoskeleton modification in head and neck squamous cell carcinoma cells.

In this study we have examined the interaction of CD44 (a major hyaluronan (HA) receptor) with a RhoA-specific guanine nucleotide exchange factor (leukemia-associated RhoGEF (LARG)) in human head and neck squamous carcinoma cells (HNSCC-HSC-3 cell line). Immunoprecipitation and immunoblot analyses indicate that CD44 and the LARG protein are expressed in HSC-3 cells and that these two proteins are physically associated as a complex. HA-CD44 binding induces LARG-specific RhoA signaling and phospholipase C epsilon (PLC epsilon) activity. In particular, the activation of RhoA-PLC epsilon by HA stimulates inositol 1,4,5-triphosphate production, intracellular Ca2+ mobilization, and the up-regulation of Ca2+/calmodulin-dependent kinase II (CaMKII), leading to phosphorylation of the cytoskeletal protein, filamin. The phosphorylation of filamin reduces its interaction with filamentous actin, promoting tumor cell migration. The CD44-LARG complex also interacts with the EGF receptor (EGFR). Most importantly, the binding of HA to the CD44-LARG-EGFR complex activates the EGFR receptor kinase, which in turn promotes Ras-mediated stimulation of a downstream kinase cascade including the Raf-1 and ERK pathways leading to HNSCC cell growth. Using a recombinant fragment of LARG (the LARG-PDZ domain) and a binding assay, we have determined that the LARG-PDZ domain serves as a direct linker between CD44 and EGFR. Transfection of the HSC-3 cells with LARG-PDZcDNA significantly reduces LARG association with CD44 and EGFR. Overexpression of the LARG-PDZ domain also functions as a dominant-negative mutant (similar to the PLC/Ca2+-calmodulin-dependent kinase II (CaMKII) and EGFR/MAPK inhibitor effects) to block HA/CD44-mediated signaling events (e.g. EGFR kinase activation, Ras/RhoA co-activation, Raf-ERK signaling, PLC epsilon-mediated inositol 1,4,5-triphosphate production, intracellular Ca2+ mobilization, CaMKII activity, filamin phosphorylation, and filamin-actin binding) and to abrogate tumor cell growth/migration. Taken together, our findings suggest that CD44 interaction with LARG and EGFR plays a pivotal role in Rho/Ras co-activation, PLC epsilon-Ca2+ signaling, and Raf/ERK up-regulation required for CaMKII-mediated cytoskeleton function and in head and neck squamous cell carcinoma progression.

Hyaluronan-CD44 interaction with IQGAP1 promotes Cdc42 and ERK signaling, leading to actin binding, Elk-1/estrogen receptor transcriptional activation, and ovarian cancer progression.

In this study, we have examined the interaction of hyaluronan (HA)-CD44 with IQGAP1 (one of the binding partners for the Rho GTPase Cdc42) in SK-OV-3.ipl human ovarian tumor cells. Immunological and biochemical analyses indicated that IQGAP1 (molecular mass of approximately 190 kDa) is expressed in SK-OV-3.ipl cells and that IQGAP1 interacts directly with Cdc42 in a GTP-dependent manner. Both IQGAP1 and Cdc42 were physically linked to CD44 in SK-OV-3.ipl cells following HA stimulation. Furthermore, the HA-CD44-induced Cdc42-IQGAP1 complex regulated cytoskeletal function via a close association with F-actin that led to ovarian tumor cell migration. In addition, the binding of HA to CD44 promoted the association of ERK2 with the IQGAP1 molecule, which stimulated both ERK2 phosphorylation and kinase activity. The activated ERK2 then increased the phosphorylation of both Elk-1 and estrogen receptor-alpha (ER alpha), resulting in Elk-1- and estrogen-responsive element-mediated transcriptional up-regulation. Down-regulation of IQGAP1 (by treating cells with IQGAP1-specific small interfering RNAs) not only blocked IQGAP1 association with CD44, Cdc42, F-actin, and ERK2 but also abrogated HA-CD44-induced cytoskeletal function, ERK2 signaling (e.g. ERK2 phosphorylation/activity, ERK2-mediated Elk-1/ER alpha phosphorylation, and Elk-1/ER alpha-specific transcriptional activation), and tumor cell migration. Taken together, these findings indicate that HA-CD44 interaction with IQGAP1 serves as a signal integrator by modulating Cdc42 cytoskeletal function, mediating Elk-1-specific transcriptional activation, and coordinating "cross-talk" between a membrane receptor (CD44) and a nuclear hormone receptor (ER alpha) signaling pathway during ovarian cancer progression.

CD44 interaction with Na+-H+ exchanger (NHE1) creates acidic microenvironments leading to hyaluronidase-2 and cathepsin B activation and breast tumor cell invasion.

We have explored CD44 (a hyaluronan (HA) receptor) interaction with a Na(+)-H(+) exchanger (NHE1) and hyaluronidase-2 (Hyal-2) during HA-induced cellular signaling in human breast tumor cells (MDA-MB-231 cell line). Immunological analyses demonstrate that CD44s (standard form) and two signaling molecules (NHE1 and Hyal-2) are closely associated in a complex in MDA-MB-231 cells. These three proteins are also significantly enriched in cholesterol and ganglioside-containing lipid rafts, characterized as caveolin and flotillin-rich plasma membrane microdomains. The binding of HA to CD44 activates Na(+)-H(+) exchange activity which, in turn, promotes intracellular acidification and creates an acidic extracellular matrix environment. This leads to Hyal-2-mediated HA catabolism, HA modification, and cysteine proteinase (cathepsin B) activation resulting in breast tumor cell invasion. In addition, we have observed the following: (i) HA/CD44-activated Rho kinase (ROK) mediates NHE1 phosphorylation and activity, and (ii) inhibition of ROK or NHE1 activity (by treating cells with a ROK inhibitor, Y27632, or NHE1 blocker, S-(N-ethyl-N-isopropyl) amiloride, respectively) blocks NHE1 phosphorylation/Na(+)-H(+) exchange activity, reduces intracellular acidification, eliminates the acidic environment in the extracellular matrix, and suppresses breast tumor-specific behaviors (e.g. Hyal-2-mediated HA modification, cathepsin B activation, and tumor cell invasion). Finally, down-regulation of CD44 or Hyal-2 expression (by treating cells with CD44 or Hyal-2-specific small interfering RNAs) not only inhibits HA-mediated CD44 signaling (e.g. ROK-mediated Na(+)-H(+) exchanger reaction and cellular pH changes) but also impairs oncogenic events (e.g. Hyal-2 activity, hyaluronan modification, cathepsin B activation, and tumor cell invasion). Taken together, our results suggest that CD44 interaction with a ROK-activated NHE1 (a Na(+)-H(+) exchanger) in cholesterol/ganglioside-containing lipid rafts plays a pivotal role in promoting intracellular/extracellular acidification required for Hyal-2 and cysteine proteinase-mediated matrix degradation and breast cancer progression.