Characteristics and Outcomes of Patients Discharged Directly Home From the Pediatric Intensive Care Unit.

Introduction: Patients admitted to the pediatric intensive care unit (PICU) typically transfer to an acute care floor prior to discharge (ACD). Various circumstances, including rapid clinical improvement, technology dependence, or capacity constraints, may lead to discharge directly to home from a PICU (DDH). This practice has been studied in adult intensive care units, but research is lacking for PICU patients. Methods: We aimed to describe characteristics and outcomes of patients requiring PICU admission who experienced DDH versus ACD. We conducted a retrospective cohort study of patients ≤18 years old admitted to our academic, tertiary care PICU between 1/1/15 and 12/31/20. Patients who died or were transferred to another facility were excluded. Baseline characteristics (including home ventilator dependence) and markers of illness severity, specifically the need for vasoactive infusion or new mechanical ventilation, were compared between groups. Admission diagnoses were categorized using the Pediatric Clinical Classification System (PECCS). Our primary outcome was hospital readmission within 30 days. Results: Of 4042 PICU admissions during the study period, 768 (19%) were DDH. Baseline demographic characteristics were similar, although DDH patients were more likely to have a tracheostomy (30% vs 5%, P < .01) and require a home ventilator at discharge (24% vs 1%, P < .01). DDH was associated with being less likely to have required a vasoactive infusion (7% vs 11%, P < .01), shorter median length of stay (LOS) (2.1 days vs 5.9 days, P < .01) and increased rate of readmission within 30 days of discharge (17% vs 14%, P < .05). However, repeat analysis after removing ventilator-dependent patients at discharge (n = 202) showed no difference in rates of readmission (14% vs 14%, P = .88). Conclusions: Direct discharge home from the PICU is a common practice. DDH and ACD groups had similar 30-day readmission rate when patient admissions with home ventilator dependence were excluded.

The Economic Burden of Musculoskeletal Disease in Children and Adolescents in the United States.

BACKGROUND: Musculoskeletal conditions are among the most common and costly conditions suffered by Americans. In 2011, there was an estimated $213 billion in annual cost of direct treatment for and lost wages due to musculoskeletal disease in the United States. Data on economic burden, however, comes mostly from the adult population, with significantly less information regarding the burden of these conditions in young patients available. The purpose of this report is to provide data on the economic burden of musculoskeletal diseases in children and adolescents in the United States. METHODS: Eleven diagnosis categories were identified, with health care visits and hospitalization data derived from ICD-9-CM codes for each of the conditions searched. The largest database utilized was the Healthcare Cost and Utilization Project (HCUP) Kids' Inpatient Database (KID). Total visits came from the KID, HCUP NEDS (emergency department), NCHS NHAMCS OP (outpatient), and NCHS NAMCS (physician office) databases. The National Health Interview Survey (NHIS) child sample was additionally searched to obtain patient/parent-reported data. RESULTS: In 2012, more than 19 million children and adolescents received treatment in medical centers, physicians' offices, and hospitals for a musculoskeletal-related condition. The most common reason for treatment (68%) was traumatic injury, followed by a pain syndrome (13%) and deformity (9%). Total hospital charges in 2012 for children and adolescents with a primary musculoskeletal-related diagnosis totaled $7.6 billion. Trauma (43%) and deformity (38%) were the major contributors to total hospital charges. CONCLUSIONS: Although we found that hospital-related charges for musculoskeletal diseases for children and adolescents in 2012 totaled $7.6 billion, this number underestimates the total cost for all pediatric musculoskeletal conditions. Musculoskeletal conditions accounted for 5.4% of hospital charges in the pediatric population. However, only 1.4% of pediatric research funding is designated to musculoskeletal research. Going forward, the data in this report may be used to further research and to stimulate development of better methods with which to measure the direct and indirect costs of musculoskeletal conditions in children. LEVEL OF EVIDENCE: Level IV-economic and decision analysis.

Musculoskeletal Imaging in Cerebral Palsy.

Scoliosis, hip dysplasia, and other lower extremity deformities are common musculoskeletal pathology found in patients with cerebral palsy. Imaging studies allow for an improved identification of patients with these issues, help to understand the pathology, and aid in planning treatment strategies. Most of these deformities are visualized using plain radiographic techniques. Occasionally, as in the case of preoperative planning, advanced imaging, such as computerized topography and MRI, can be used for additional information. This article provides insight into the various imaging techniques for these musculoskeletal issues and aids in better care for patients with cerebral palsy.

Abnormal benzodiazepine and zinc modulation of GABAA receptors in an acquired absence epilepsy model.

Brain cholesterol synthesis inhibition (CSI) at a young age in rats has been shown to be a faithful model of acquired absence epilepsy, a devastating condition for which few therapies or models exist. We employed the CSI model to study cellular mechanisms of acquired absence epilepsy in Long-Evans Hooded rats. Patch-clamp, whole-cell recordings were compared from neurons acutely dissociated from the nucleus reticularis of thalamus (nRt) treated and untreated with a cholesterol synthesis inhibitor, U18666A. In U18666A-treated animals, 91% of rats developed EEG spike-waves (SWs). Patchclamp results revealed that although there was no remarkable change in GABAA receptor affinity, both a loss of ability of benzodiazepines to enhance GABAA-receptor responses and an increase of Zn2+ inhibition of GABAA-receptor responses of nRt neurons occurred in Long-Evans Hooded rats previously administered U18666A. This change was specific, since no significant changes were found in neurons exposed to the GABA allosteric modulator, pentobarbital. Taken collectively, these findings provide evidence for abnormalities in benzodiazepine and Zn2+ modulation of GABAA receptors in the CSI model, and suggest that decreased gamma2 subunit expression may underlie important aspects of generation of thalamocortical SWs in atypical absence seizures. The present results are also consistent with recent findings that mutation of the gamma2 subunit of the GABAA receptor changes benzodiazepine modulation in families with generalized epilepsy syndromes.

High-affinity epibatidine binding of functional, human alpha7-nicotinic acetylcholine receptors stably and heterologously expressed de novo in human SH-EP1 cells.

Human nicotinic acetylcholine receptor (nAChR) alpha7 subunits were stably and heterologously expressed in native nAChR-null SH-EP1 human epithelial cells. Immunofluorescence staining shows alpha7 subunit protein expression in virtually every transfected cell. Microautoradiographic analysis identifies 125I-labeled alpha-bungarotoxin (I-Bgt) binding sites corresponding to human alpha7 (halpha7)-nAChRs on the surface of most cells. I-Bgt binds to halpha7-nAChRs in membrane fractions with a typical apparent K(D) value of approximately 5 nM and B(max) value of approximately 1 pmol/mg membrane protein, and 62% of these sites are expressed on the cell surface. Function of heterologously expressed halpha7-nAChRs is evident as rapid, transient inward current responses to (-)-nicotine. Nicotine treatment of transfected cells produces dose- and time-dependent increases (up to approximately 100%) in numbers of I-Bgt binding sites. Epibatidine is a useful ligand for studies of nAChRs containing alpha3 or alpha4 subunits (K(D) values of about 100 or 10 pM, respectively). halpha7-nAChRs expressed in transfected SH-EP1 cells also exhibit picomolar affinity binding of 3H-labeled epibatidine (K(D) value of approximately 0.6 nM). Studies of several forms of native or heterologously expressed rat or human alpha7-nAChRs confirm high-affinity and mutually exclusive interaction with both epibatidine and alpha-bungarotoxin. Rank order potencies for drugs acting to compete for binding of either radioligand are similar (methyllycaconitine > dimethylphenyl-piperazinium > nicotine approximately cytisine > carbamylcholine approximately D-tubocurarine). These results demonstrate that transfected SH-EP1 cells are excellent models for studies of heterologously expressed, human alpha7-nAChRs that exhibit ligand binding and functional properties like native alpha7-nAChRs and that epibatdine is useful as a probe for human alpha7-nAChRs.

Regulation by cycloheximide and lowered temperature of cell-surface alpha7-nicotinic acetylcholine receptor expression on transfected SH-EP1 cells.

Heterologous expression of functional, nicotinic acetylcholine receptors (nAChR) in mammalian cells has been difficult to achieve or optimize, even for nAChR containing only one kind of subunit. In this study, we determined effects of lowered temperature or of exposure to the protein synthesis inhibitor cycloheximide (CHX) on cell surface expression of homomeric alpha7-nAChR in transfected SH-EP1 human epithelial cells. We found that incubation of cells for 2 days at 25 degrees C or in the presence of 0.5-2 microg/mL of CHX caused approximately four- or approximately eight-fold increases, respectively, in surface binding sites for 125I-labeled alpha-bungarotoxin (I-Bgt). These increases were accompanied by increases in peak whole-cell current responses to nicotinic agonists. Either treatment lowered protein synthesis and cell proliferation, but experiments using puromycin indicated that a reduction in protein synthesis or cell proliferation per se was not sufficient to increase surface binding. I-Bgt binding to whole-cell membrane pools increased in response to either treatment, suggesting that the increase in surface binding was due, at least in part, to an increase in intracellular receptor levels. The cyclophilin inhibitor cyclosporin A reduced surface expression in untreated as well as CHX- or 25 degrees C-treated cells. The results suggest practical means for increasing cell surface and functional expression of alpha7-nAChR. Although these effects are not simply due to protein synthesis inhibition or reduced cell proliferation, they do involve an increase in intracellular receptor pool size.

1-Methyl-4-phenylpridinium (MPP+)-induced functional run-down of GABA(A) receptor-mediated currents in acutely dissociated dopaminergic neurons.

We have evaluated GABA(A)receptor function during treatment of 1-methyl-4-phenylpridinium (MPP+) using patch-clamp perforated whole-cell recording techniques in acutely dissociated dopaminergic (DAergic) neurons from rat substantia nigra compacta (SNc). Gamma-aminobutyric acid (GABA), glutamate or glycine induced inward currents (I(GABA), I(Glu), I(Gly)) at a holding potential (VH) of -45 mV. The I(GABA) was reversibly blocked by the GABA(A) receptor antagonist, bicuculline, suggesting that I(GABA) is mediated through the activation of GABA(A) receptors. During extracellular perfusion of MPP+ (1-10 microm), I(GABA) , but neither I(Glu) nor I(Gly), declined (termed run-down) with repetitive agonist applications, indicating that the MPP+-induced I(GABA) run-down occurred earlier than I(Gly) or I(Glu) under our experimental conditions. The MPP+-induced I(GABA) run-down can be prevented by a DA transporter inhibitor, mazindol, and can be mimicked by a metabolic inhibitor, rotenone. Using conventional whole-cell recording with different concentrations of ATP in the pipette solution, I(GABA) run-down can be induced by decreasing intracellular ATP concentrations, or prevented by supplying intracellular ATP, indicating that I(GABA) run-down is dependent on intracellular ATP concentrations. A GABA(A) receptor positive modulator, pentobarbital (PB), potentiated the declined I(GABA) and eliminated I(GABA) run-down. Corresponding to these patch-clamp data, tyrosine hydroxylase (TH) immunohistochemical staining showed that TH-positive cell loss was protected by PB during MPP+ perfusion. It is concluded that extracellular perfusion of MPP+ induces a functional run-down of GABA(A) receptors, which may cause an imbalance of excitation and inhibition of DAergic neurons.

Electrophysiological, pharmacological, and molecular evidence for alpha7-nicotinic acetylcholine receptors in rat midbrain dopamine neurons.

Dopamine (DA) neurons located in the mammalian midbrain have been generally implicated in reward and drug reinforcement and more specifically in nicotine dependence. However, roles played by nicotinic acetylcholine receptors, including those composed of alpha7-subunits [alpha7-nicotinic acetylcholine receptors (nAChRs)], in modulation of DA signaling and in nicotine dependence are not clearly understood. Although midbrain slice recording has been used previously to identify functional alpha7-nAChRs, these preparations are not optimally designed for extremely rapid and reproducible drug application, and rapidly desensitized, alpha7-nAChR-mediated currents may have been underestimated or not detected. Here, we use patch-clamp, whole-cell current recordings from single neurons acutely dissociated from midbrain nuclei and having features of DA neurons to characterize acetylcholine-induced, inward currents that rapidly activate and desensitize, are mimicked by the alpha7-nAChR-selective agonist, choline, blocked by the alpha7-nAChR-selective antagonists, methyllycaconitine and alpha-bungarotoxin, and are similar to those of heterologously expressed, human alpha7-nAChRs. We also use reverse transcriptase-polymerase chain reaction, in situ hybridization, and immunocytochemical staining to demonstrate nAChR alpha7 subunit gene expression as message and protein in the rat substantia nigra pars compacta and ventral tegmental area. Expression of alpha7 subunit message and of alpha7-nAChR-mediated responses is developmentally regulated, with both being absent in samples taken from rats at postnatal day 7, but later becoming present and increasing over the next 2 weeks. Collectively, this electrophysiological, pharmacological, and molecular evidence indicates that nAChR alpha7 subunits and functional alpha7-nAChRs are expressed somatodendritically by midbrain DA neurons, where they may play important physiological roles and contribute to nicotine reinforcement and dependence.

Functional properties of homomeric, human alpha 7-nicotinic acetylcholine receptors heterologously expressed in the SH-EP1 human epithelial cell line.

alpha 7-Nicotinic acetylcholine receptors (alpha 7-nAChRs) are broadly distributed in the central nervous system, where they play important roles in chemical and electrical signaling, and perhaps in neurite outgrowth, synaptic plasticity, and neuronal death/survival. To help elucidate their normal and pathophysiological roles, we have heterologously expressed human alpha 7-nAChR in transfected SH-EP1 human epithelial cells. Reverse transcription-polymerase chain reaction and mRNA fluorescence in situ hybridization analyses demonstrate expression of human alpha 7 subunits as messenger RNA. Patch-clamp recordings exploiting a novel strategy to prevent functional rundown of whole-cell peak current responses to repeated acute challenges with nicotinic agonists show successful expression of functional alpha 7-nAChR that mediate inward currents characterized by rapid phases of activation and inactivation. Concentration-response curves show that nicotine, acetylcholine, and choline are efficacious agonists at human alpha 7-nAChRs. Current-voltage relationships show inward rectification for agonist-induced currents. Human alpha 7-nAChRs exhibit some sensitivity to alpha 7-nAChR antagonists alpha-bungarotoxin (Bgt) or methyllycaconitine (MLA) when applied coincidentally with agonist, but much higher affinity block occurs when cells and alpha 7-nAChRs are pre-exposed to antagonists for 2 min before challenge with agonist. Both Bgt and MLA are competitive inhibitors of alpha 7-nAChR function. Whole-cell current peak amplitudes and half-times for inactivation of alpha 7-nAChR functional responses to nicotine are dramatically reduced in the absence of extracellular Ca2+, suggestive of high Ca2+ permeability of the alpha 7-nAChR channel. Thus, heterologously expressed human alpha 7-nAChR in mammalian cells have properties of native alpha 7-nAChR or of alpha 7-nAChR heterologously expressed in other systems and serve as excellent models for studies of molecular bases of alpha 7-nAChR function.

Characterization of human alpha 4 beta 2-nicotinic acetylcholine receptors stably and heterologously expressed in native nicotinic receptor-null SH-EP1 human epithelial cells.

Naturally expressed nicotinic acetylcholine receptors composed of alpha4 and beta2 subunits (alpha4beta2-nAChR) are the predominant form of high affinity nicotine binding site in the brain implicated in nicotine reward, mediation of nicotinic cholinergic transmission, modulation of signaling through other chemical messages, and a number of neuropsychiatric disorders. To develop a model system for studies of human alpha4beta2-nAChR allowing protein chemical, functional, pharmacological, and regulation of expression studies, human alpha4 and beta2 subunits were stably introduced into the native nAChR-null human epithelial cell line SHEP1. Heterologously expressed alpha4beta2-nAChR engage in high-affinity, specific binding of 3H-labeled epibatidine (H-EBDN; macroscopic KD = 10 pM; kon = 0.74/min/nM, koff = 0.013/min). Immunofluorescence studies show alpha4 and beta2 subunit protein expression in virtually every transfected cell, and microautoradiographic studies show expression of 125I-labeled iodo-deschloroepibatidine binding sites in most cells. H-EBDN binding competition studies reveal high affinity for nicotinic agonists and lower affinity for nicotinic antagonists. Heterologously expressed alpha4beta2-nAChR functional studies using 86Rb+ efflux assays indicate full efficacy of epibatidine, nicotine, and acetylcholine; partial efficacy for 1,1-dimethyl-4-phenyl-piperazinium, cytisine, and suberyldicholine; competitive antagonism by dihydro-beta-erythroidine, decamethonium, and methyllycaconitine; noncompetitive antagonism by mecamylamine and eserine; and mixed antagonism by pancuronium, hexamethonium, and d-tubocurarine. These results demonstrate utility of transfected SH-EP1 cells as models for studies of human alpha4beta2-nAChR, and they also reveal complex relationships between apparent affinities of drugs for radioligand binding and functional sites on human alpha4beta2-nAChR.