Delirium Screening in Critically Ill Children: Secondary Analysis of the Multicenter PICU Up! Pilot Trial Dataset, 2019-2020.

OBJECTIVES: To determine the patient-level factors associated with performing daily delirium screening in PICUs with established delirium screening practices. DESIGN: A secondary analysis of 2019-2020 prospective data from the baseline phase of the PICU Up! pilot stepped-wedge multicenter trial (NCT03860168). SETTING: Six PICUs in the United States. PATIENTS: One thousand sixty-four patients who were admitted to a PICU for 3 or more days. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of 1064 patients, 74% (95% CI, 71-76%) underwent delirium screening at least once during their PICU stay. On 57% of the 8965 eligible patient days, screening was conducted. The overall prevalence of delirium was 46% across all screened days, and 64% of screened patients experienced delirium at some point during their PICU stay. Factors associated with greater adjusted odds ratio (aOR) of increased daily delirium screening included PICU stay longer than 15 days compared with 1-3 days (aOR 3.36 [95% CI, 2.62-4.30]), invasive mechanical ventilation as opposed to room air (aOR 1.67 [95% CI, 1.32-2.12]), dexmedetomidine infusions (aOR 1.23 [95% CI, 1.04-1.44]) and propofol infusions (aOR 1.55 [95% CI, 1.08-2.23]). Conversely, decreased aOR of daily delirium screening was associated with female gender (aOR 0.78 [95% CI, 0.63-0.96]), and the administration of continuous infusions of opioids (aOR 0.75 [95% CI, 0.63-0.90]) or ketamine (aOR 0.48 [95% CI, 0.29-0.79]). Neither patient age, the presence of family or physical restraints, or benzodiazepine infusions were associated with daily delirium screening rates. CONCLUSIONS: In the 2019-2020 PICU UP! cohort, across six PICUs, delirium screening occurred on only 57% of days, despite the presence of established practices. Female gender, patients in the early stages of their PICU stay, and patients not receiving mechanical ventilation were associated with lower odds of daily delirium screening. Our results highlight the need for structured quality improvement processes to both standardize and increase the frequency of delirium screening.

Novel NMP split liver model recapitulates human IRI and demonstrates ferroptosis modulators as a new therapeutic strategy.

BACKGROUND: Almost 9%of deceased donor livers are discarded as marginal donor livers (MDL) due to concern of severe ischemia reperfusion injury (IRI). Emerging data supports ferroptosis (iron regulated hepatocellular death) as an IRI driver, however lack of robust preclinical model limits therapeutic testing. In this manuscript we describe the development of a novel rigorous internal control system utilizing normothermic perfusion of split livers to test ferroptosis regulators modulating IRI. METHODS: Upon institutional approval, split human MDLs were placed on our normothermic perfusion machine, Perfusion Regulated Organ Therapeutics with Enhanced Controlled Testing (PROTECT), pumping arterial and portal blood. Experiment 1 compared right (UR) and left (UL) lobes to validate PROTECT. Experiment 2 assessed ferroptosis regulator Deferoxamine in Deferoxamine Agent Treated (DMAT) vs. No Agent Internal Control (NAIC) lobes. Liver serology, histology, and ferroptosis genes were assessed. RESULTS: Successful MDL perfusion validated PROTECT with no ALT or AST difference between UR and UL (∆ALT UR: 235, ∆ALT UL: 212; ∆AST UR: 576, ∆AST UL: 389). Liver injury markers increased in NAIC vs. DMAT (∆ALT NAIC: 586, ∆ALT DMAT: -405; ∆AST NAIC: 617, ∆AST DMAT: -380). UR and UL had similar expression of ferroptosis regulators RPL8,HO-1 and HIFα. Significantly decreased intrahepatic iron (p = .038), HO-1 and HIFα in DMAT (HO-1 NAIC: 6.93, HO-1 DMAT: 2.74; HIFαNAIC: 8.67, HIFαDMAT: 2.60)and no hepatocellular necrosis or immunohistochemical staining (Ki67/Cytokeratin-7) differences were noted. CONCLUSION: PROTECT demonstrates the therapeutic utility of a novel normothermic perfusion split liver system for drug discovery and rapid translatability of therapeutics, driving a paradigm change in organ recovery and transplant medicine. Our study using human livers, provides preliminary proof of concept for the novel role of ferroptosis regulators in driving IRI.

Perioperative Factors Associated With Changes in Troponin T During Coronary Artery Bypass Grafting.

OBJECTIVE: Investigate important clinical and operative variables associated with increases in cardiac troponin T (cTnT) as indicators of myocardial injury after coronary artery bypass grafting (CABG). DESIGN: Prospective cohort study. SETTING: Single university hospital. PARTICIPANTS: The study comprised 626 patients undergoing isolated CABG from April 2008 through April 2010 with a validation cohort (n = 686) from 2015-2017. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Perioperative variables were registered prospectively. The extent of diffuse coronary atherosclerosis and significant stenoses were assessed with preoperative coronary angiography. Mixed model analysis was used to construct a statistical model explaining the course of cTnT concentrations. The model was adjusted for preoperative and intraoperative/postoperative myocardial infarction (MI) for independent assessment of additional variables. Clinical factors associated with increased cTnT concentrations during and after CABG were longer duration of cardiopulmonary bypass (p < 0.001), higher preoperative creatinine (p < 0.001), New York Heart Association functional classification IV (p = 0.006), reduced LVEF (p = 0.034), higher preoperative C-reactive protein (p = 0.049), and intraoperative/postoperative MI (p < 0.001). Factors associated with decreasing cTnT concentrations during CABG were higher BSA (p < 0.001) and a recent preoperative MI (p < 0.001). The extent of diffuse coronary atherosclerosis and significant stenoses were not associated with changes in cTnT (p = 0.35). Results were similar in the validation cohort. CONCLUSIONS: Left ventricular ejection fraction, New York Heart Association classification, kidney function, inflammation status, duration of cardiopulmonary bypass, body surface area, and preoperative MI were associated with the cTnT rise-and-fall pattern related to myocardial injury after CABG. Information regarding these variables may be valuable when using cTnT in the diagnostic workup of postoperative MI.

Mutations in the endothelin receptor type A cause mandibulofacial dysostosis with alopecia.

The endothelin receptor type A (EDNRA) signaling pathway is essential for the establishment of mandibular identity during development of the first pharyngeal arch. We report four unrelated individuals with the syndrome mandibulofacial dysostosis with alopecia (MFDA) who have de novo missense variants in EDNRA. Three of the four individuals have the same substitution, p.Tyr129Phe. Tyr129 is known to determine the selective affinity of EDNRA for endothelin 1 (EDN1), its major physiological ligand, and the p.Tyr129Phe variant increases the affinity of the receptor for EDN3, its non-preferred ligand, by two orders of magnitude. The fourth individual has a somatic mosaic substitution, p.Glu303Lys, and was previously described as having Johnson-McMillin syndrome. The zygomatic arch of individuals with MFDA resembles that of mice in which EDNRA is ectopically activated in the maxillary prominence, resulting in a maxillary to mandibular transformation, suggesting that the p.Tyr129Phe variant causes an EDNRA gain of function in the developing upper jaw. Our in vitro and in vivo assays suggested complex, context-dependent effects of the EDNRA variants on downstream signaling. Our findings highlight the importance of finely tuned regulation of EDNRA signaling during human craniofacial development and suggest that modification of endothelin receptor-ligand specificity was a key step in the evolution of vertebrate jaws.

Mutations in DDX3X Are a Common Cause of Unexplained Intellectual Disability with Gender-Specific Effects on Wnt Signaling.

Intellectual disability (ID) affects approximately 1%-3% of humans with a gender bias toward males. Previous studies have identified mutations in more than 100 genes on the X chromosome in males with ID, but there is less evidence for de novo mutations on the X chromosome causing ID in females. In this study we present 35 unique deleterious de novo mutations in DDX3X identified by whole exome sequencing in 38 females with ID and various other features including hypotonia, movement disorders, behavior problems, corpus callosum hypoplasia, and epilepsy. Based on our findings, mutations in DDX3X are one of the more common causes of ID, accounting for 1%-3% of unexplained ID in females. Although no de novo DDX3X mutations were identified in males, we present three families with segregating missense mutations in DDX3X, suggestive of an X-linked recessive inheritance pattern. In these families, all males with the DDX3X variant had ID, whereas carrier females were unaffected. To explore the pathogenic mechanisms accounting for the differences in disease transmission and phenotype between affected females and affected males with DDX3X missense variants, we used canonical Wnt defects in zebrafish as a surrogate measure of DDX3X function in vivo. We demonstrate a consistent loss-of-function effect of all tested de novo mutations on the Wnt pathway, and we further show a differential effect by gender. The differential activity possibly reflects a dose-dependent effect of DDX3X expression in the context of functional mosaic females versus one-copy males, which reflects the complex biological nature of DDX3X mutations.

A novel test for recessive contributions to complex diseases implicates Bardet-Biedl syndrome gene BBS10 in idiopathic type 2 diabetes and obesity.

Rare-variant association studies in common, complex diseases are customarily conducted under an additive risk model in both single-variant and burden testing. Here, we describe a method to improve detection of rare recessive variants in complex diseases termed RAFT (recessive-allele-frequency-based test). We found that RAFT outperforms existing approaches when the variant influences disease risk in a recessive manner on simulated data. We then applied our method to 1,791 Finnish individuals with type 2 diabetes (T2D) and 2,657 matched control subjects. In BBS10, we discovered a rare variant (c.1189A>G [p.Ile397Val]; rs202042386) that confers risk of T2D in a recessive state (p = 1.38 × 10(-6)) and would be missed by conventional methods. Testing of this variant in an established in vivo zebrafish model confirmed the variant to be pathogenic. Taken together, these data suggest that RAFT can effectively reveal rare recessive contributions to complex diseases overlooked by conventional association tests.

Mannose-Binding Lectin Levels in Critically Ill Children With Severe Infections.

OBJECTIVES: Low mannose-binding lectin levels and haplotypes associated with low mannose-binding lectin production have been associated with infection and severe sepsis. We tested the hypothesis that mannose-binding lectin levels would be associated with severe infection in a large cohort of critically ill children. DESIGN: Prospective cohort study. SETTING: Medical and Surgical PICUs, Boston Children's Hospital. PATIENTS: Children less than 21 years old admitted to the ICUs from November 2009 to November 2010. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We measured mannose-binding lectin levels in 479 of 520 consecutively admitted children (92%) with severe or life-threatening illness. We genotyped 213 Caucasian children for mannose-binding lectin haplotype tagging variants and assigned haplotypes. In the univariate analyses of mannose-binding lectin levels with preadmission characteristics, levels were higher in patients with preexisting renal disease. Patients who received greater than 100 mL/kg of fluids in the first 24 hours after admission had markedly lower mannose-binding lectin, as did patients who underwent spinal fusion surgery. Mannose-binding lectin levels had no association with infection status at admission, or with progression from systemic inflammatory response syndrome to sepsis or septic shock. Although mannose-binding lectin haplotypes strongly influenced mannose-binding lectin levels in the predicted relationship, low mannose-binding lectin-producing haplotypes were not associated with increased risk of infection. CONCLUSIONS: Mannose-binding lectin levels are largely genetically determined. This relationship was preserved in children during critical illness, despite the effect of large-volume fluid administration on mannose-binding lectin levels. Previous literature evaluating an association between mannose-binding lectin levels and severe infection is inconsistent; we found no relationship in our PICU cohort. We found that mannose-binding lectin levels were lower after aggressive fluid resuscitation and suggest that studies of mannose-binding lectin in critically ill patients should assess mannose-binding lectin haplotypes to reflect preillness levels.

Establishing a Quality Improvement Program for Pediatric In-hospital Cardiac Arrest.

Background: Pediatric In-hospital Cardiac Arrest (IHCA) is a rare event with a 50-55% mortality rate. Techniques of Cardiopulmonary Resuscitation (CPR), medication and electrical therapy timing, team dynamics, simulation and debriefing programs are associated with improved outcomes. This study aimed to improve outcomes after IHCA by describing and implementing quality improvement processes that cross and coordinate among traditional siloed pediatric resuscitation team structures. Methods: We chose three outcome measures: (1) return of spontaneous circulation (ROSC), (2) 24-hour survival after IHCA, and (3) survival to hospital discharge. Process outcomes include (1) hot debriefs performed with a standardized form, (2) code documentation using a revised form, and (3) formal code team review presented to a central Emergency Management Committee, using a standardized form. Results: One hundred and thirty-two patients experienced 176 events during the 36-month study period. Survival to hospital discharge increased from 33% during year 1 to 60% during year 2 (P < 0.05) but decreased to 45% in year 3. Both hot debrief performance and code documentation process methods did not demonstrate widespread adoption, but formal code team review was documented in 80% of events quite rapidly. Conclusions: There are common traits inherent to effective CPR team response. Ensuring optimal performance of these common tasks and techniques in every pediatric IHCA event in our hospital is being addressed by committee reorganization, task simplification, new technology acquisition and enhanced feedback loops. Early outcome analysis shows initial improvement in survival to hospital discharge after pediatric IHCA.

Bolus gastric feeds improve nutrition delivery to mechanically ventilated pediatric medical patients: Results of the COntinuous vs BOlus multicenter trial.

BACKGROUND: Comparison of bolus gastric feeding (BGF) vs continuous gastric feeding (CGF) with respect to timing and delivery of energy and protein in mechanically ventilated (MV) pediatric patients has not been investigated. We hypothesized that bolus delivery would shorten time to goal nutrition and increase the percentage of goal feeds delivered. METHODS: Multicenter, prospective, randomized comparative effectiveness trial conducted in seven pediatric intensive care units (PICUs). Eligibility criteria included patients aged 1 month to 12 years who were intubated within 24 h of PICU admission, with expected duration of ventilation at least 48 h, and who were eligible to begin enteral nutrition within 48 h. Exclusion criteria included patients with acute or chronic gastrointestinal pathology or acute surgery. RESULTS: We enrolled 158 MV children between October 2015 and April 2018; 147 patients were included in the analysis (BGF = 72, CGF = 75). Children in the BGF group were slightly older than those in the CGF; otherwise, the two groups had similar demographic characteristics. There was no difference in the percentage of patients in each group who achieved goal feeds. Time to goal feeds was shorter in the BGF group (hazard ratio 1.5 [CI 1.02-2.33]; P = 0.0387). Median percentage of target kilocalories (median kcal 0.78 vs 0.59; P ≤ 0.0001) and median percentage of protein delivered (median protein 0.77 vs 0.59; P ≤ 0.0001) was higher for BGF patients. There was no difference in serial oxygen saturation index between groups. CONCLUSION: Our study demonstrated shorter time to achieve goal nutrition via BGF compared with CGF in MV pediatric patients. This resulted in increased delivery of target energy and nutrition. Further study is needed in other PICU populations.

Zebrafish mutants calamity and catastrophe define critical pathways of gene-nutrient interactions in developmental copper metabolism.

Nutrient availability is an important environmental variable during development that has significant effects on the metabolism, health, and viability of an organism. To understand these interactions for the nutrient copper, we used a chemical genetic screen for zebrafish mutants sensitive to developmental copper deficiency. In this screen, we isolated two mutants that define subtleties of copper metabolism. The first contains a viable hypomorphic allele of atp7a and results in a loss of pigmentation when exposed to mild nutritional copper deficiency. This mutant displays incompletely penetrant skeletal defects affected by developmental copper availability. The second carries an inactivating mutation in the vacuolar ATPase that causes punctate melanocytes and embryonic lethality. This mutant, catastrophe, is sensitive to copper deprivation revealing overlap between ion metabolic pathways. Together, the two mutants illustrate the utility of chemical genetic screens in zebrafish to elucidate the interaction of nutrient availability and genetic polymorphisms in cellular metabolism.

In vivo correction of a Menkes disease model using antisense oligonucleotides.

Although the molecular basis of many inherited metabolic diseases has been defined, the availability of effective therapies in such disorders remains problematic. Menkes disease is a fatal neurodegenerative disorder due to loss-of-function mutations in the ATP7A gene encoding a copper-transporting P-type Atpase. To develop therapeutic approaches in affected patients, we have identified a zebrafish model of Menkes disease termed calamity that results from splicing defects in the zebrafish orthologue of the ATP7A gene. Embryonic-recessive lethal mutants have impaired copper homeostasis that results in absent melanin pigmentation, impaired notochord formation, and hindbrain neurodegeneration. In this current study, we have attempted to rescue these striking phenotypic alterations by using a series of antisense morpholino oligonucleotides directed against the splice-site junctions of two mutant calamity alleles. Our findings reveal a robust and complete correction of the copper-deficient defects of calamity in association with the generation of the WT Menkes protein in all rescued mutants. Interestingly, a quantitative analysis of atp7a-specific transcripts suggests that competitive translational regulation may account for the synthesis of WT protein in these embryos. This in vivo correction of Menkes disease through the rescue of aberrant splicing may provide therapeutic options in this fatal disease and illustrates the potential for zebrafish models of human genetic disease in the development of treatments based on the principles of interactions of synthetic oligonucleotide analogues with mRNA.

Fast saccades toward numbers: simple number comparisons can be made in as little as 230 ms.

Visual psychophysicists have recently developed tools to measure the maximal speed at which the brain can accurately carry out different types of computations (H. Kirchner & S. J. Thorpe, 2006). We use this methodology to measure the maximal speed with which individuals can make magnitude comparisons between two single-digit numbers. We find that individuals make such comparisons with high accuracy in 306 ms on average and are able to perform above chance in as little as 230 ms. We also find that maximal speeds are similar for "larger than" and "smaller than" number comparisons and in a control task that simply requires subjects to identify the number in a number-letter pair. The results suggest that the brain contains dedicated processes involved in implementing basic number comparisons that can be deployed in parallel with processes involved in low-level visual processing.

Continuous Versus Bolus Gastric Feeding in Children Receiving Mechanical Ventilation: A Systematic Review.

BACKGROUND: Nutrition guidelines recommend enteral nutrition in the form of gastric feedings for critically ill children and acknowledge a lack of evidence describing an optimal method for providing these feedings. OBJECTIVE: To determine the state of the science regarding the efficacy of bolus (intermittent) or continuous gastric feedings to improve nutrition delivery in critically ill children receiving mechanical ventilation. METHODS: Five hundred seventy-nine abstracts met the inclusion criteria and were screened by 2 reviewers according to prespecified criteria. Full-text reviews were performed on 28 articles; 11 studies were selected for detailed analysis. Because of the small number of eligible studies, broader searches were conducted. RESULTS: Only 5 studies with a collective enrollment of fewer than 200 children closely addressed the specific research question. These 5 studies did not report any similarity in feeding regimens, nor did they report nutritional outcomes. Two of the articles described findings from the same study population. Although 4 of the 5 studies randomized children to bolus versus continuous feedings, only 3 studies described attainment of nutrient delivery goals in both the intervention and the control groups; the remaining study did not report this outcome. The heterogeneity in methodology and outcomes among the 5 studies did not allow for a meta-analysis. CONCLUSIONS: The dearth of evidence regarding best practices and outcomes related to bolus versus continuous gastric feedings in critically ill children receiving mechanical ventilation requires additional rigorous investigation.

Combined zebrafish-yeast chemical-genetic screens reveal gene-copper-nutrition interactions that modulate melanocyte pigmentation.

Hypopigmentation is a feature of copper deficiency in humans, as caused by mutation of the copper (Cu(2+)) transporter ATP7A in Menkes disease, or an inability to absorb copper after gastric surgery. However, many causes of copper deficiency are unknown, and genetic polymorphisms might underlie sensitivity to suboptimal environmental copper conditions. Here, we combined phenotypic screens in zebrafish for compounds that affect copper metabolism with yeast chemical-genetic profiles to identify pathways that are sensitive to copper depletion. Yeast chemical-genetic interactions revealed that defects in intracellular trafficking pathways cause sensitivity to low-copper conditions; partial knockdown of the analogous Ap3s1 and Ap1s1 trafficking components in zebrafish sensitized developing melanocytes to hypopigmentation in low-copper environmental conditions. Because trafficking pathways are essential for copper loading into cuproproteins, our results suggest that hypomorphic alleles of trafficking components might underlie sensitivity to reduced-copper nutrient conditions. In addition, we used zebrafish-yeast screening to identify a novel target pathway in copper metabolism for the small-molecule MEK kinase inhibitor U0126. The zebrafish-yeast screening method combines the power of zebrafish as a disease model with facile genome-scale identification of chemical-genetic interactions in yeast to enable the discovery and dissection of complex multigenic interactions in disease-gene networks.

Long-term weight loss decreases the nontraditional cardiovascular risk factors interleukin-18 and matrix metalloproteinase-9 in obese subjects.

The objective of the study was to investigate the effect of long-term (3.2 years) weight loss on serum levels of the nontraditional cardiovascular risk factors interleukin (IL)-18 and matrix metalloproteinase (MMP)-9. Moreover, we wanted to assess the significance of the magnitude of the weight loss and evaluate the potential effects of 36 months of treatment with the lipase inhibitor orlistat on these parameters. Sixty-eight abdominally obese subjects completed 8 weeks of very low energy diet (600-800 kcal/d) followed by 36 months of randomized treatment with either orlistat or placebo together with lifestyle intervention. Serum levels of IL-18, MMP-9, and leptin were measured by flowmetric xMAP technology (Luminex, Austin, TX). Changes in the levels of IL-18, MMP-9, and leptin were similar in the orlistat and the placebo group during this study. Thus, the 2 groups were combined for further analysis. A weight loss of 8.4 +/- 8.8 kg from baseline to 3.2 years was associated with significant decreases in IL-18 (P < .001), MMP-9 (P < .01), and leptin (P < .001). Matrix metalloproteinase-9 was, however, significantly increased after 8 weeks of very low energy diet-induced weight loss (P < .05). The long-term changes in IL-18 were significantly associated with changes in body mass index independent of changes in blood pressure and lipids (P < .05). Levels and changes of IL-18 and MMP-9 were significantly positively associated at 3.2 years (P < .01). Long-term changes in leptin were significantly associated with changes in IL-18 (P < .01) at 3.2 years. Diet-induced long-term weight loss decreased IL-18 and MMP-9. The decrease in IL-18 was associated with changes in body mass index independent of changes in blood pressure and lipids, indicating that even a minor weight reduction (>5%) has beneficial effects on nontraditional cardiovascular risk markers. Orlistat treatment had no independent effects on IL-18, MMP-9, or leptin in the present study.

Weight loss larger than 10% is needed for general improvement of levels of circulating adiponectin and markers of inflammation in obese subjects: a 3-year weight loss study.

OBJECTIVE: To investigate the effects of: I) short- (8 weeks), II) long-term (3 years) weight loss, and III) the degree of weight loss on circulating levels of adiponectin, high sensitive-C reactive protein (hs-CRP), and fibrinogen in obese subjects. Moreover, to evaluate the effect of the lipase inhibitor, orlistat, on these parameters. DESIGN: Weight loss induced in 93 obese subjects (mean weight: 108.9+/-15.8 kg) through 8-week very-low-energy diet (VLED, 800 kcal/day) followed by randomization to orlistat or placebo together with lifestyle intervention for further 3 years. Adiponectin and hs-CRP were measured at baseline, after 8 weeks of VLED and 6, 12, and 36 months after the VLED by flowmetric xMAP technology (Luminex Multi-Analyte Profiling System, Luminex Corp., Austin, TX, USA). Fibrinogen was measured in a coagulation assay. RESULTS: Weight loss after VLED treatment was 14.3+/-4.5 kg and after 3 years 7.7+/-8.7 kg. Orlistat-treated subjects regained 3.9 kg less than placebo-treated from the end of the VLED to 3 years (P=0.01). No differences were detected between the two groups regarding changes in adiponectin, hs-CRP, or fibrinogen. Accordingly, the groups were combined for further analyses. Serum adiponectin increased by 22% (P<0.05) after the VLED but returned to baseline after 3 years. Both short- and long-term weight losses needed to be in excess of 10% (approximately 12 kg) in order to increase adiponectin levels significantly. Weight loss was associated with a significant decrease in hs-CRP. Fibrinogen decreased by 12% (P<0.05) after 3 years. CONCLUSIONS: In obese subjects, weight loss was associated with an increase in serum adiponectin and a decrease in hs-CRP and plasma fibrinogen. Long-term weight loss (3 years) must exceed 10% to induce a combined significant improvement in these inflammatory markers.

Essential role for fibrillin-2 in zebrafish notochord and vascular morphogenesis.

Recent studies demonstrate that lysyl oxidase cuproenzymes are critical for zebrafish notochord formation, but the molecular mechanisms of copper-dependent notochord morphogenesis are incompletely understood. We, therefore, conducted a forward genetic screen for zebrafish mutants that exhibit notochord sensitivity to lysyl oxidase inhibition, yielding a mutant with defects in notochord and vascular morphogenesis, puff daddygw1 (pfdgw1). Meiotic mapping and cloning reveal that the pfdgw1 phenotype results from disruption of the gene encoding the extracellular matrix protein fibrillin-2, and the spatiotemporal expression of fibrillin-2 is consistent with the pfdgw1 phenotype. Furthermore, each aspect of the pfdgw1 phenotype is recapitulated by morpholino knockdown of fibrillin-2. Taken together, the data reveal a genetic interaction between fibrillin-2 and the lysyl oxidases in notochord formation and demonstrate the importance of fibrillin-2 in specific early developmental processes in zebrafish.

Copper and iron disorders of the brain.

Copper and iron are transition elements essential for life. These metals are required to maintain the brain's biochemistry such that deficiency or excess of either copper or iron results in central nervous system disease. This review focuses on the inherited disorders in humans that directly affect copper or iron homeostasis in the brain. Elucidation of the molecular genetic basis of these rare disorders has provided insight into the mechanisms of copper and iron acquisition, trafficking, storage, and excretion in the brain. This knowledge permits a greater understanding of copper and iron roles in neurobiology and neurologic disease and may allow for the development of therapeutic approaches where aberrant metal homeostasis is implicated in disease pathogenesis.

Copper deficiency.

PURPOSE OF REVIEW: Reports of the neurologic findings in adults with acquired copper deficiency as well as the development of novel models for Menkes disease have permitted a greater understanding of the role of copper in the central nervous system. A role of mitochondrial copper homeostasis in cellular energy metabolism suggests roles for this metal in cellular differentiation and biochemical adaptation. RECENT FINDINGS: Acquired copper deficiency in adults is reported with increasing frequency, often without any identifiable cause. Chemical genetic studies identified a zebrafish model of Menkes disease that can be used for high-throughput therapeutics and revealed a hierarchy of copper distribution during development. Studies in mice reveal that the copper transport protein Ctr1 is essential for intestinal copper absorption and suggest a unique role for copper in axonal extension, excitotoxic cell death and synaptic plasticity in the central nervous system. Lastly, recent biochemical studies indicate a central role for the mitochondrial matrix in cellular copper metabolism. SUMMARY: The recent developments in our understanding of copper deficiency and copper homeostasis outlined in this review provide an exciting platform for future investigations intended to elucidate the role of copper in central nervous system development and disease.