RESUMEN
ABSTRACT: BACKGROUND: Pediatric neurocritical care (PNCC) and pediatric neurointensive care units (neuro-PICU) are growing fields. Although some institutions have established independent neuro-PICUs meeting most Neurocritical Care Society (NCS) standards for neurocritical care units, many centers lack the resources to do so. We describe an alternative neuro-PICU model as a designated unit within a mixed pediatric intensive care unit (PICU) and its effects on nursing sentiment. METHODS: We established a 6-bed neuro-PICU within a 36-bed noncardiac PICU. Charge nurses were tasked with admitting PNCC patients into these beds. For nursing expertise, we used a core group of 12 PNCC specialty nurses and instituted PNCC nursing education to PICU nurses. We observed the number of PNCC patients admitted to neuro-PICU beds and surveyed charge nurses to identify barriers to assigning patients. We surveyed PICU nursing staff to explore sentiment regarding PNCC before and after establishing the neuro-PICU. Nursing criteria were compared with NCS standards. RESULTS: In the 40-month period, our PICU saw 2060 PNCC admissions. Overall, occupied neuro-PICU beds housed PNCC patients 74.1% of the time. The biggest barriers to patient placement were too many competing placement requests, not enough neuro-PICU beds when specialty census was high, and difficulty assigning one nurse to two PNCC patients. In surveys after establishing the neuro-PICU, compared to before, experienced nurses reported being more interested in obtaining Emergency Neurological Life Support certification (94.2% vs 80.6%, P = .0495), and inexperienced nurses reported being more familiar with PNCC clinical pathways (53.5% vs 31.7%, P = .0263). Most NCS criteria related to nursing organization were met. CONCLUSIONS: Focused neuro-PICUs should be developed to complement advances in the field of PNCC. Alternative neuro-PICU models are possible and can increase nursing interest in further education and awareness of clinical pathways, but barriers exist that require institutional commitment to nursing development to sustain the delivery of specialized care to this population.
Asunto(s)
Unidades de Cuidado Intensivo Pediátrico , Enfermería en Neurociencias , Humanos , Enfermería de Cuidados Críticos , Niño , Encuestas y Cuestionarios , Enfermería Pediátrica , Personal de Enfermería en Hospital , Cuidados CríticosRESUMEN
BACKGROUND: Divergence between intra-arterial catheters blood pressure (ABP) and noninvasive oscillometry (NIBP) may affect the care of children with brain arteriovenous malformations (bAVMs). We described the agreement between ABP and NIBP in these children. METHODS: We conducted a retrospective review of patients admitted to the pediatric intensive care unit between 2017 and 2023 with bAVM rupture. Paired ABP and NIBP measurements were collected. Bland-Altman analyses were used to assess agreement. Correlation analysis was conducted between higher ABP and divergence between systolic BP (SBP) measurements. Hypertension was defined as mean arterial pressure (MAP) exceeding age-based 95th percentile. RESULTS: Thirty-four patients with 1901 BP pairs were observed. Bias overall was acceptable, but standard deviation (SD) was high. The best agreement of MAP was in non-hypertensive (bias 1.23â¯mmHg, SD 8.03â¯mmHg) and radial arterial catheters (bias 1.83â¯mmHg, SD 9.08â¯mmHg) subgroups. Bias for SBP was higher in hypertension (10.98â¯mmHg) and in infratentorial bAVMs (7.42â¯mmHg), suggesting poorer agreement in these subgroups. There were significant correlations between intra-arterial MAP and SBP divergence (R = +0.346, p<.001) and between intra-arterial SBP and SBP divergence (R = +0.677, p<.001), suggesting divergence widens with higher BP. Around 25â¯% of measurement pairs diverged to where one measurement crossed the clinical threshold for treatment, while the other did not, with ABP being more frequently higher than NIBP. CONCLUSIONS: There is good agreement between ABP and NIBP, particularly in non-hypertensive ranges and with radial arterial catheters. Measurements, however, diverge in hypertension. Further research must define age-based thresholds, validate methods of BP measurement, and determine the effect of BP reduction on outcomes in these children.
Asunto(s)
Presión Arterial , Determinación de la Presión Sanguínea , Malformaciones Arteriovenosas Intracraneales , Oscilometría , Humanos , Niño , Malformaciones Arteriovenosas Intracraneales/fisiopatología , Femenino , Masculino , Estudios Retrospectivos , Determinación de la Presión Sanguínea/métodos , Adolescente , Presión Arterial/fisiología , Oscilometría/métodos , Preescolar , Hipertensión/fisiopatología , Presión Sanguínea/fisiologíaRESUMEN
BACKGROUND: Nurses are vital partners in the development of pediatric neurocritical care (PNCC) programs. Nursing expertise is acknowledged to be an integral component of high-quality specialty patient care in the field, but little guidance exists regarding educational requirements to build that expertise. We sought to obtain expert consensus from nursing professionals and physicians on curricular priorities for specialized PNCC nursing education in pediatric centers across the United States. METHODS: We used a modified Delphi study technique surveying a multidisciplinary expert panel of nursing professionals and physicians. Online surveys were distributed to 44 panelists over three rounds to achieve consensus on curricular topics deemed essential for PNCC nursing education. During each round, panelists were asked to rate topics as essential or not essential, as well as given opportunities to provide feedback and suggest changes. Feedback was shared anonymously to the panelist group throughout the process. RESULTS: From 70 initial individual topics, the consensus process yielded 19 refined topics that were confirmed to be essential for a PNCC nursing curriculum by the expert panel. Discrepancies existed regarding how universally to recommend topics of advanced neuromonitoring, such as brain tissue oxygenation; specialized neurological assessments, such as the serial neurological assessment in pediatrics or National Institutes of Health Stroke Scale; and some disease-based populations. Panelists remarked that not all centers see specific diseases, and not all centers currently employ advanced neuromonitoring technologies and skills. CONCLUSIONS: We report 19 widely accepted curricular priorities that can serve as a standard educational base for PNCC nursing. Developing education for nurses in PNCC will complement PNCC programs with targeted nursing expertise that extends comprehensive specialty care to the bedside. Further work is necessary to effectively execute educational certification programs, implement nursing standards in the field, and evaluate the impact of nursing expertise on patient care and outcomes.
RESUMEN
The rapid development of organic-inorganic hybrid perovskite solar cells has resulted in laboratory-scale devices having power conversion efficiencies that are competitive with commercialised technologies. However, hybrid perovskite solar cells are yet to make an impact beyond the research community, with translation to large-area devices fabricated by industry-relevant manufacturing methods remaining a critical challenge. Here we report the first demonstration of hybrid perovskite solar cell modules, comprising serially-interconnected cells, produced entirely using industrial roll-to-roll printing tools under ambient room conditions. As part of this development, costly vacuum-deposited metal electrodes are replaced with printed carbon electrodes. A high-throughput experiment involving the analysis of batches of 1600 cells produced using 20 parameter combinations enabled rapid optimisation over a large parameter space. The optimised roll-to-roll fabricated hybrid perovskite solar cells show power conversion efficiencies of up to 15.5% for individual small-area cells and 11.0% for serially-interconnected cells in large-area modules. Based on the devices produced in this work, a cost of ~0.7 USD W-1 is predicted for a production rate of 1,000,000 m² per year in Australia, with potential for further significant cost reductions.
RESUMEN
OBJECTIVES: Pediatric neurocritical care (PNCC) is a quickly growing subspecialty within pediatric critical care medicine. Standards for care, education, and application of neuromonitoring technologies in PNCC are still being developed. We sought to identify and improve knowledge deficits in neurocritical care with an educational boot camp for nurses. SETTING: Quaternary children's hospital with 36 PICU beds. DESIGN: Preinterventional and postinterventional study. METHODS: A 2-day boot camp course covering neurologic and neurosurgical topics pertinent to PNCC was provided to 46 pediatric acute and critical care nurses divided into three cohorts over 3 years. Participant characteristics were collected, and precourse and postcourse knowledge assessments were administered. RESULTS: Regarding participant characteristics, neither critical care registered nurse certification nor years of nursing experience were associated with better precourse baseline knowledge. Knowledge gaps spanned bedside neurologic assessments, physiologic goals in brain injury, and side effects of neurocritical care medications. In postcourse assessments, all participants showed improvement in scores, and most participants sustained improvements after 6 months. Nurses reported significant improvement in self-reported confidence in caring for the PNCC population. We also observed shorter ICU lengths of stay, decreased hospital incident reports, and decreased time to stroke imaging, although these programmatic metrics cannot be credited to nursing education alone. CONCLUSIONS: PNCC programs should include nursing expertise in the field. However, topics specific to PNCC may not be adequately addressed by existing general critical care nursing education and certification. A multimodal educational boot camp can be an effective method to improve nursing knowledge in PNCC. Our results demonstrate that specialty nursing education in PNCC is both innovative and feasible, with the potential to improve patient care. Further research is needed to determine the benefits of specialty education on quality of care and clinical outcomes.
RESUMEN
Within the developing embryo is a microcosm of cell type diversity. Single cell RNA-sequencing (scRNA-seq) is used to reveal cell types, typically by grouping cells according to their gene regulatory states. However, both across and within these regulatory states are additional layers of cellular diversity represented by the differential expression of genes that govern cell function. Here, we analyzed scRNA-seq data representing the late gastrula stage of Strongylocentrotus purpuratus (purple sea urchin) to understand the patterning of transporters belonging to the ABC and SLC families. These transporters handle diverse substrates from amino acids to signaling molecules, nutrients and xenobiotics. Using transporter-based clustering, we identified unique transporter patterns that are both shared across cell lineages, as well as those that were unique to known cell types. We further explored three patterns of transporter expression in mesodermal cells including secondary mesenchyme cells (pigment cells and blastocoelar cells) and skeletogenic cells (primary mesenchyme cells). The results revealed the enrichment of SMTs potentially involved in nutrient absorption (SLC5A9, SLC7A11, SLC35F3, and SLC52A3) and skeletogenesis (SLC9A3, SLC13A2/3/5, and SLC39A13) in pigment cells and blastocoelar cells respectively. The results indicated that the strategy of clustering by cellular activity can be useful for discovering cellular populations that would otherwise remain obscured.
Asunto(s)
Embrión de Mamíferos , Células Madre Mesenquimatosas , Humanos , Linaje de la Célula , Gástrula , Proteínas de Transporte de MembranaRESUMEN
Macrocyclization has proven to be a beneficial strategy to improve upon some of the disadvantages of peptides as therapeutics. Nevertheless, many peptide cyclization strategies are not compatible with inâ vitro display technologies like mRNA display. Here we describe the novel amino acid p-chloropropynyl phenylalanine (pCPF). pCPF is a substrate for a mutant phenylalanyl-tRNA synthetase and its introduction into peptides via inâ vitro translation leads to spontaneous peptide macrocyclization in the presence of peptides containing cysteine. Macrocyclization occurs efficiently with a wide variety of ring sizes. Moreover, pCPF can be reacted with thiols after charging onto tRNA, enabling the testing of diverse ncAAs in translation. The versatility of pCPF should facilitate downstream studies of translation and enable the creation of novel macrocyclic peptide libraries.
Asunto(s)
Aminoácidos , Aminoacil-ARNt Sintetasas , Aminoácidos/química , Fenilalanina/metabolismo , Aminoacil-ARNt Sintetasas/metabolismo , Péptidos/química , ARN de Transferencia/metabolismoRESUMEN
BACKGROUND: The pathophysiology of pediatric hepatic encephalopathy (HE) is not well understood. Various serum biomarkers associated with HE may provide insight into its pathology, but their use and interpretation in clinical practice for diagnosis and prognostication remain undetermined. We sought to investigate reported correlations of serum biomarkers with presence and degree of HE in children. METHODS: We conducted a systematic review of studies examining novel serum biomarkers and cytokines in association with HE that included children on PubMed, Embase, Lilacs, and Scopus. We utilized Covidence for abstract and text review by 2 independent reviewers for each study. RESULTS: We reviewed 2824 unique publications; 15 met criteria for inclusion. Categories of biomarkers reported were inflammatory cytokines, products of amino acid metabolism, trace elements and vitamins, and hepatic and neuro biomarkers. Of 19 individual biomarkers, only 5 were measured in more than 1 study. Elevations in interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-alpha) were most commonly reported as associated with HE. Notably, we observed lower average IL-6 and TNF-alpha levels in pediatric-only studies compared to mixed age studies. Overall, high bias and poor applicability to our review question was observed. We encountered low numbers of studies with pediatric focus, and few conducted with low bias study designs. CONCLUSION: Investigated biomarkers span a large range of categories and suggest potentially useful correlations with HE. Further well-designed prospective biomarker research is necessary to better elucidate the pathogenesis of HE in children and improve early detection and clinical care.
Asunto(s)
Encefalopatía Hepática , Humanos , Niño , Encefalopatía Hepática/etiología , Factor de Necrosis Tumoral alfa , Interleucina-6 , Biomarcadores , CitocinasRESUMEN
OBJECTIVES: Determine agreement between Pediatric Cerebral Performance Category (PCPC) scores integrated into clinical workflow and traditional investigator-assigned scores. DESIGN: Longitudinal study. SETTING: A single-center quaternary-care academic institution. SUBJECTS: Children admitted to the PICU between November 2019 and April 2020. INTERVENTIONS: Providers assigned PCPC scores as part of daily workflow. Investigators assigned scores using retrospective chart review. MEASUREMENTS AND MAIN RESULTS: Of 803 patients admitted to the PICU, 782 survived and were included. Admission and discharge scores were recorded in 95% and 90% of patients, respectively. Agreement between provider- and investigator-assigned scores was excellent, with a weighted kappa of 0.87 (95% CI, 0.84-0.90) and 0.80 (95% CI, 0.76-0.84) for admission and discharge. CONCLUSIONS: Provider-assigned PCPC scores, documented as standard of care, are largely concordant with retrospective investigator-assigned scores. Measurement of cognitive functional status can be successfully integrated into daily provider workflow for use in the clinical, quality improvement, and research arenas.
Asunto(s)
Enfermedad Crítica , Hospitalización , Niño , Humanos , Lactante , Estudios Retrospectivos , Estudios Longitudinales , Enfermedad Crítica/terapia , Alta del Paciente , Unidades de Cuidado Intensivo PediátricoRESUMEN
OBJECTIVE: Hemodynamic management in pediatric neurosurgical patients is essential for maintaining cerebral perfusion pressure (CPP), avoiding hemorrhage, and preventing secondary neurological injury. Antihypertensive infusions approved for pediatrics are not widely studied in the pediatric neurosurgical population and may have adverse effects on intracranial pressure (ICP), contributing to reduced CPP. Clevidipine is an ultra-rapid-acting intravenous antihypertensive agent used for hemodynamic control in adult surgical patients. In pediatric patients, clevidipine is safe and effective in controlling blood pressure in the perioperative period, although studies evaluating its effect on ICP in neurosurgical patients are lacking. The objective of this research was to evaluate the effect of clevidipine on ICP in pediatric neurosurgical patients. METHODS: This single-center retrospective study involved patients admitted to the pediatric ICU between January 1, 2017, and December 31, 2020. Patients eligible for inclusion had ICP monitoring devices and received clevidipine infusion for a minimum of 6 hours postoperatively, with at least one ICP measurement pre- and postinfusion. Excluded patients had an elevated preinfusion ICP > 20 mm Hg. The primary outcome was the average change in ICP from preinfusion baseline to hours 6 to < 12, 12 to < 24, and 24 to < 48 of clevidipine infusion. Secondary outcomes included frequency of ICP measurements > 20 mm Hg, CPP measurements < 50 mm Hg, treatment failure defined by a need for concurrent antihypertensive infusion, and frequency of elevated serum triglycerides > 200 mg/dL. Descriptive data were expressed as frequency with percentage or median with interquartile range as appropriate. Analysis of continuous outcome variable data involved Mann-Whitney U-tests with an alpha significance of 0.05. RESULTS: Data from 47 patients were included in the analysis. The average change in ICP from preinfusion baseline to 48 hours was < 1 mm Hg. Of 3025 total postinfusion ICP measurements in 47 patients, 67 measurements (2.2%) in 13 patients (28%) were > 20 mm Hg. CPP measurements < 50 mm Hg occurred in 16 of 45 patients (36%). Three patients (6.4%) required use of a secondary antihypertensive medication infusion, and 5 of 14 patients (36%) had serum triglycerides > 200 mg/dL. CONCLUSIONS: Use of clevidipine had minimal effect on ICP. The results of this study suggest that clevidipine is effective at safely maintaining ICP and CPP measurements without detrimental adverse effects in pediatric neurosurgical patients.
Asunto(s)
Antihipertensivos , Hipertensión Intracraneal , Adulto , Humanos , Niño , Antihipertensivos/farmacología , Antihipertensivos/uso terapéutico , Estudios Retrospectivos , Presión Intracraneal/fisiología , Triglicéridos/farmacología , Triglicéridos/uso terapéutico , Circulación Cerebrovascular/fisiologíaRESUMEN
Neuropsychiatric disorders classically lack defining brain pathologies, but recent work has demonstrated dysregulation at the molecular level, characterized by transcriptomic and epigenetic alterations1-3. In autism spectrum disorder (ASD), this molecular pathology involves the upregulation of microglial, astrocyte and neural-immune genes, the downregulation of synaptic genes, and attenuation of gene-expression gradients in cortex1,2,4-6. However, whether these changes are limited to cortical association regions or are more widespread remains unknown. To address this issue, we performed RNA-sequencing analysis of 725 brain samples spanning 11 cortical areas from 112 post-mortem samples from individuals with ASD and neurotypical controls. We find widespread transcriptomic changes across the cortex in ASD, exhibiting an anterior-to-posterior gradient, with the greatest differences in primary visual cortex, coincident with an attenuation of the typical transcriptomic differences between cortical regions. Single-nucleus RNA-sequencing and methylation profiling demonstrate that this robust molecular signature reflects changes in cell-type-specific gene expression, particularly affecting excitatory neurons and glia. Both rare and common ASD-associated genetic variation converge within a downregulated co-expression module involving synaptic signalling, and common variation alone is enriched within a module of upregulated protein chaperone genes. These results highlight widespread molecular changes across the cerebral cortex in ASD, extending beyond association cortex to broadly involve primary sensory regions.
Asunto(s)
Trastorno del Espectro Autista , Corteza Cerebral , Variación Genética , Transcriptoma , Humanos , Trastorno del Espectro Autista/genética , Trastorno del Espectro Autista/metabolismo , Trastorno del Espectro Autista/patología , Corteza Cerebral/metabolismo , Corteza Cerebral/patología , Neuronas/metabolismo , ARN/análisis , ARN/genética , Transcriptoma/genética , Autopsia , Análisis de Secuencia de ARN , Corteza Visual Primaria/metabolismo , Neuroglía/metabolismoRESUMEN
Neuromonitoring has become more standardized in adult neurocritical care, but the utility of different neuromonitoring modalities in children remains debated. We aimed to describe the use of neuromonitoring in critically ill children with and without primary neurological diseases. We conducted a retrospective review of patients admitted to a 32-bed, non-cardiac PICU during a 12-month period. Neuro-imaging, electroencephalogram (EEG), cerebral oximetry (NIRS), automated pupillometry, transcranial doppler (TCD), intracranial pressure (ICP) monitoring, brain tissue oxygenation (PbtO2), primary diagnosis, and outcome were extracted. Neuromonitoring use by primary diagnosis and associations with outcome were observed. Of 1946 patients, 420 received neuro-imaging or neuromonitoring. Primary non-neurological diagnoses most frequently receiving neuromonitoring were respiratory, hematologic/oncologic, gastrointestinal/liver, and infectious/inflammatory. The most frequently used technologies among non-neurological diagnoses were neuro-imaging, EEG, pupillometry, and NIRS. In the multivariate analysis, pupillometry use was associated with mortality, and EEG, NIRS, and neuro-imaging use were associated with disability. Frequencies of TCD and PbtO2 use were too small for analysis. Neuromonitoring is prevalent among various diagnoses in the PICU, without clear benefit on outcomes when used in an ad hoc fashion. We need standard guidance around who, when, and how neuromonitoring should be applied to improve the care of critically ill children.
RESUMEN
Sea urchins are premier model organisms for the study of early development. However, the lengthy generation times of commonly used species have precluded application of stable genetic approaches. Here, we use the painted sea urchin Lytechinus pictus to address this limitation and to generate a homozygous mutant sea urchin line. L. pictus has one of the shortest generation times of any currently used sea urchin. We leveraged this advantage to generate a knockout mutant of the sea urchin homolog of the drug transporter ABCB1, a major player in xenobiotic disposition for all animals. Using CRISPR/Cas9, we generated large fragment deletions of ABCB1 and used these readily detected deletions to rapidly genotype and breed mutant animals to homozygosity in the F2 generation. The knockout larvae are produced according to expected Mendelian distribution, exhibit reduced xenobiotic efflux activity and can be grown to maturity. This study represents a major step towards more sophisticated genetic manipulation of the sea urchin and the establishment of reproducible sea urchin animal resources.
Asunto(s)
Lytechinus , Xenobióticos , Animales , Técnicas Genéticas , Larva/genética , Lytechinus/genética , Erizos de Mar/genéticaRESUMEN
BACKGROUND: Cannabis refers to a plant in the family Cannabaceae, which has been used medically, recreationally, and industrially. The last two decades, in particular, have seen a large increase in the volume of literature on this topic. The present bibliometric analysis aims to capture the characteristics of scholarly journal publications on the topic of cannabis and cannabinoid research. METHODS: Searches were run on the Scopus database on April 02, 2021, as follows "(TITLE (cannabi* OR hashish OR marijuana OR marihuana)) AND ( LIMIT-TO ( DOCTYPE,"ar" ) OR LIMIT-TO ( DOCTYPE,"re" ) )". Results were exported on the same day to prevent discrepancies between daily database updates. Only "article" and "review" publication types were included; no further search limits were applied. The "article" publication type includes publications featuring original research, whereas "review" includes reviews and conference papers. The following data were collected: number of publications (in total and per year), authors, and journals; open access status; publications per journal; journals publishing the highest volume of literature and their impact factors, language of publication; document type; publication country; author affiliations; funding sponsors; most highly cited publications; and most highly published authors. Trends in this subset of publications were identified and presented. Bibliometric networks were constructed using the software tool VOSviewer. RESULTS: A total of 29 802 publications (10 214 open access), published by 65 109 authors, were published in 5474 journals from 1829 to 2021. The greatest number of publications was published over the last 20 years. The journal that published the largest number of publications was Drug and Alcohol Dependence (n = 705). The most productive countries included the USA (n = 12 420), the UK (n = 2236), and Canada (n = 2062); many of the most common institutional affiliations and funding sponsors originated from these countries. CONCLUSIONS: The number of publications published on the topic of cannabis follows an upward trend. Over the past 20 years, the volume of cannabis research has grown steeply, which can be attributed to a large amount of funding dedicated to researching this topic. Future research should continue to investigate changes in the publication characteristics of emerging research, as the volume of publications on this topic is expected to rapidly grow.
RESUMEN
BACKGROUND: Disorders of water and sodium balance can occur after brain injury. Prolonged polyuria resulting from central diabetes insipidus and cerebral salt wasting complicated by gradient washout and a type of secondary nephrogenic diabetes insipidus, however, has not been described previously, to the best of our knowledge. We report an unusual case of an infant with glioblastoma who, after tumor resection, was treated for concurrent central diabetes insipidus and cerebral salt wasting complicated by secondary nephrogenic diabetes insipidus. CASE PRESENTATION: A 5-month-old Hispanic girl was found to have a large, hemorrhagic, suprasellar glioblastoma causing obstructive hydrocephalus. Prior to mass resection, she developed central diabetes insipidus. Postoperatively, she continued to have central diabetes insipidus and concurrent cerebral salt wasting soon after. She was managed with a vasopressin infusion, sodium supplementation, fludrocortisone, and urine output replacements. Despite resolution of her other major medical issues, she remained in the pediatric intensive care unit for continual and aggressive management of water and sodium derangements. Starting on postoperative day 18, her polyuria began increasing dramatically and did not abate with increasing vasopressin. Nephrology was consulted. Her blood urea nitrogen was undetectable during this time, and it was thought that she may have developed a depletion of inner medullary urea and osmotic gradient: a "gradient washout." Supplemental dietary protein was added to her enteral nutrition, and her fluid intake was decreased. Within 4 days, her blood urea nitrogen increased, and her vasopressin and fluid replacement requirements significantly decreased. She was transitioned soon thereafter to subcutaneous desmopressin and transferred out of the pediatric intensive care unit. CONCLUSIONS: Gradient washout has not been widely reported in humans, although it has been observed in the mammalian kidneys after prolonged polyuria. Although not a problem with aquaporin protein expression or production, gradient washout causes a different type of secondary nephrogenic diabetes insipidus because the absence of a medullary gradient impairs water reabsorption. We report a case of an infant who developed complex water and sodium imbalances after brain injury. Prolonged polyuria resulting from both water and solute diuresis with low enteral protein intake was thought to cause a urea gradient washout and secondary nephrogenic diabetes insipidus. The restriction of fluid replacements and supplementation of enteral protein appeared adequate to restore the renal osmotic gradient and efficacy of vasopressin.
Asunto(s)
Lesiones Encefálicas , Diabetes Insípida Nefrogénica , Diabetes Insípida Neurogénica , Diabetes Mellitus , Animales , Niño , Diabetes Insípida Nefrogénica/complicaciones , Femenino , Humanos , Lactante , Riñón , SodioRESUMEN
The ATP-sensitive potassium (K(ATP)) channel regulates pancreatic ß-cell function by linking metabolic status to electrical activity. Syntaxin-1A (Syn-1A), a SNARE protein mediating exocytotic fusion, binds and inhibits the K(ATP) channel via the nucleotide-binding folds (NBFs) of its sulfonylurea receptor-1 (SUR1) regulatory subunit. In this study, we elucidated the precise regions within the NBFs required for Syn-1A-mediated K(ATP) inhibition, using in vitro binding assays, whole cell patch clamp and FRET assay. Specifically, NBF1 and NBF2 were each divided into three subregions, Walker A (W(A)), signature sequence linker, and Walker B (W(B)), to make GST fusion proteins. In vitro binding assays revealed that Syn-1A associates with W(A) and W(B) regions of both NBFs. Patch clamp recordings on INS-1 and primary rat ß-cells showed that Syn-1A-mediated channel inhibition was reversed by co-addition of NBF1-W(B) (not NBF1-W(A)), NBF2-W(A), and NBF2-W(B). The findings were corroborated by FRET studies showing that these truncates disrupted Syn-1A interactions with full-length SUR1. To further identify the binding sites, series single-site mutations were made in the Walker motifs of the NBFs. Only NBF1-W(A) (K719M) or NBF2-W(A) (K1385M) mutant no longer bound to Syn-1A; K1385M failed to disrupt Syn-1A-mediated inhibition of K(ATP) channels. These data suggest that NBF1-W(A) (Lys-719) and NBF2-W(A) (Lys-1385) are critical for Syn-1A-K(ATP) channel interaction. Taken together, Syn-1A intimately and functionally associates with the SUR1-NBF1/2 dimer via direct interactions with W(A) motifs and sites adjacent to W(B) motifs of NBF1 and NBF2 but transduces its inhibitory actions on K(ATP) channel activity via some but not all of these NBF domains.
Asunto(s)
Transportadoras de Casetes de Unión a ATP/metabolismo , Células Secretoras de Insulina/metabolismo , Canales de Potasio de Rectificación Interna/metabolismo , Pliegue de Proteína , Receptores de Droga/metabolismo , Sintaxina 1/metabolismo , Transportadoras de Casetes de Unión a ATP/genética , Secuencias de Aminoácidos , Animales , Sitios de Unión , Células HEK293 , Humanos , Células Secretoras de Insulina/citología , Masculino , Canales de Potasio de Rectificación Interna/genética , Estructura Terciaria de Proteína , Ratas , Ratas Wistar , Receptores de Droga/genética , Receptores de Sulfonilureas , Sintaxina 1/genéticaRESUMEN
ATP-sensitive potassium (K(ATP)) channels are regulated by a variety of cytosolic factors (adenine nucleotides, Mg(2+), phospholipids, and pH). We previously reported that K(ATP) channels are also regulated by endogenous membrane-bound SNARE protein syntaxin-1A (Syn-1A), which binds both nucleotide-binding folds of sulfonylurea receptor (SUR)1 and 2A, causing inhibition of K(ATP) channel activity in pancreatic islet ß-cells and cardiac myocytes, respectively. In this study, we show that ATP dose-dependently inhibits Syn-1A binding to SUR1 at physiological concentrations, with the addition of Mg(2+) causing a decrease in the ATP-induced inhibitory effect. This ATP disruption of Syn-1A binding to SUR1 was confirmed by FRET analysis in living HEK293 cells. Electrophysiological studies in pancreatic ß-cells demonstrated that reduced ATP concentrations increased K(ATP) channel sensitivity to Syn-1A inhibition. Depletion of endogenous Syn-1A in insulinoma cells by botulinum neurotoxin C1 proteolysis followed by rescue with exogenous Syn-1A showed that Syn-1A modulates K(ATP) channel sensitivity to ATP. Thus, our data indicate that although both ATP and Syn-1A independently inhibit ß-cell K(ATP) channel gating, they could also influence the sensitivity of K(ATP) channels to each other. These findings provide new insight into an alternate mechanism by which ATP regulates pancreatic ß-cell K(ATP) channel activity, not only by its direct actions on Kir6.2 pore subunit, but also via ATP modulation of Syn-1A binding to SUR1.
Asunto(s)
Transportadoras de Casetes de Unión a ATP/metabolismo , Adenosina Trifosfato/metabolismo , Células Secretoras de Insulina/metabolismo , Canales de Potasio de Rectificación Interna/metabolismo , Receptores de Droga/metabolismo , Sintaxina 1/metabolismo , Transportadoras de Casetes de Unión a ATP/genética , Adenosina Trifosfato/genética , Animales , Células HEK293 , Humanos , Activación del Canal Iónico/fisiología , Ratones , Canales de Potasio de Rectificación Interna/genética , Unión Proteica , Ratas , Ratas Sprague-Dawley , Receptores de Droga/genética , Receptores de Sulfonilureas , Sintaxina 1/genéticaRESUMEN
Cab45b is a cytosolic Ca(2+)-binding protein reported to regulate zymogen secretion in pancreatic acini. We now show that Cab45b is also expressed in pancreatic islet beta-cells and interacts there with the Sec1-Munc18 protein Munc18b. We employed patch clamp cell capacitance measurements to show that antibodies against Cab45b inhibited depolarization-evoked membrane capacitance increments, suggesting an impact on beta-cell granule exocytosis, both the readily releasable granule pool and refilling of this pool. Site-specific mutants in the Cab45b EF-hands were used to dissect the molecular interactions involved in Cab45b function. Mutants in EF-hands 2 and 3 had no detectable effects on interaction of Cab45b with Munc18b and did not affect the depolarization-evoked calcium currents, but remarkably, they facilitated the complex formation of Munc18b with syntaxin-2 and -3. As a result, these two EF-hand mutants inhibited beta-cell membrane capacitance increments. This inhibition is mediated via Munc18b because Munc18b silencing with small interfering RNA abolished the effects of these two mutants. The results suggest a mechanism for Cab45b action that involves regulating the dynamic association of Munc18b with SNAREs to impact beta-cell granule exocytosis.