Post-discharge outcomes of hospitalized children diagnosed with acute SARS-CoV-2 or MIS-C

Introduction

Hospitalized children diagnosed with SARS-CoV-2-related conditions are at risk for new or persistent symptoms and functional impairments. Our objective was to analyze post-hospital symptoms, healthcare utilization, and outcomes of children previously hospitalized and diagnosed with acute SARS-CoV-2 infection or Multisystem Inflammatory Syndrome in Children (MIS-C).

Methods

Prospective, multicenter electronic survey of parents of children <18 years of age surviving hospitalization from 12 U.S. centers between January 2020 and July 2021. The primary outcome was a parent report of child recovery status at the time of the survey (recovered vs. not recovered). Secondary outcomes included new or persistent symptoms, readmissions, and health-related quality of life. Multivariable backward stepwise logistic regression was performed for the association of patient, disease, laboratory, and treatment variables with recovered status.

Results

The children [n = 79; 30 (38.0%) female] with acute SARS-CoV-2 (75.7%) or MIS-C (24.3%) had a median age of 6.5 years (interquartile range 2.0-13.0) and 51 (64.6%) had a preexisting condition. Fifty children (63.3%) required critical care. One-third [23/79 (29.1%)] were not recovered at follow-up [43 (31, 54) months post-discharge]. Admission C-reactive protein levels were higher in children not recovered vs. recovered [5.7 (1.3, 25.1) vs. 1.3 (0.4, 6.3) mg/dl, p = 0.02]. At follow-up, 67% overall had new or persistent symptoms. The most common symptoms were fatigue (37%), weakness (25%), and headache (24%), all with frequencies higher in children not recovered. Forty percent had at least one return emergency visit and 24% had a hospital readmission. Recovered status was associated with better total HRQOL [87 (77, 95) vs. 77 (51, 83), p = 0.01]. In multivariable analysis, lower admission C-reactive protein [odds ratio 0.90 (95% confidence interval 0.82, 0.99)] and higher admission lymphocyte count [1.001 (1.0002, 1.002)] were associated with recovered status.

Conclusions

Children considered recovered by their parents following hospitalization with SARS-CoV-2-related conditions had less symptom frequency and better HRQOL than those reported as not recovered. Increased inflammation and lower lymphocyte count on hospital admission may help to identify children needing longitudinal, multidisciplinary care.

Clinical Trial Registration

ClinicalTrials.gov (NCT04379089).

Importance of Control Groups for Evaluating Long-Term Behavioral and Cognitive Outcomes of Controlled Cortical Impact in Immature Rats

Therapies are limited for pediatric traumatic brain injury (TBI), especially for the very young who can experience long-term consequences to learning, memory, and social behavior. Animal models of pediatric TBI have yielded mechanistic insights, but demonstration of clinically relevant long-term behavioral and/or cognitive deficits has been challenging. We characterized short- and long-term outcomes in a controlled cortical impact (CCI) model of pediatric TBI using a panel of tests between 2 weeks and ∼4 months after injury. Male rats with CCI at postnatal Day (PND) 10 were compared with three control groups: Naïve, Anesthesia, and Craniotomy. Motor testing (PND 25-33), novel object recognition (NOR; PND 40-50), and multiple tasks in water maze (WM; PND 65-100) were followed by social interaction tests (PND 120-140). Anesthesia rats performed the same as Naïve rats in all tasks. TBI rats, when compared with Naïve controls, had functional impairments across most tests studied. The most sensitive cognitive processes affected by TBI included those that required fast one-trial learning (NOR, WM), flexibility of acquired memory traces (reversals in WM), response strategies (WM), or recognition memory in the setting of reciprocal social interactions. Both TBI and Craniotomy groups demonstrated increased rates of decision making across several WM tasks, suggesting disinhibition of motor responses. When the TBI group was compared with the Craniotomy group, however, deficits were detected in a limited number of outcomes. The latter included learning speed (WM), cognitive flexibility (WM), and social recognition memory. Notably, effects of craniotomy, when compared with Naïve controls, spanned across multiple tasks, and in some tasks, could reach the effect sizes observed in TBI. These results highlight the importance of appropriate control groups in pediatric CCI models. In addition, the study demonstrates the high sensitivity of comprehensive cognitive testing to detect long-term effects of early-age craniotomy and TBI and provides a template for future testing of experimental therapies.

Bone Turnover Markers Including Undercarboxylated Osteocalcin Are Associated With Mortality Risk in Older Men

Osteocalcin in its undercarboxylated form (ucOC) may influence diabetes risk; however, its relationship with all-cause and cause-specific mortality is unclear. Whether other bone turnover markers (BTMs) are associated with mortality risk differently from ucOC also remains uncertain. Our aim was to determine associations of serum ucOC with all-cause and cause-specific mortality and compare these with the corresponding associations of serum total osteocalcin (TOC), procollagen type I N-propeptide (PINP), and collagen type 1 C-terminal cross-linked telopeptide (CTX) in older men. We conducted a prospective cohort study of 3871 community-dwelling men, aged 77.0 ± 3.6 years at baseline, followed for a median of 12.3 years. Exposure variables were ucOC, TOC, PINP, and CTX concentrations assayed in serum. Outcomes were incidence of all deaths and deaths due to cardiovascular disease (CVD) or cancer, ascertained using death registry data. Cox regression analyses adjusted for cardiovascular risk factors and prevalent CVD and for prevalent cancer in analyses of cancer-related mortality. Higher concentrations of ucOC, PINP, and CTX were associated with all-cause mortality (hazard ratio [HR] per 1 standard deviation increase: ucOC 1.12, 95% confidence interval [CI] 1.06-1.18, p < 0.001; PINP HR = 1.06, 95% CI 1.01-1.11, p = 0.009; CTX HR = 1.13, 95% CI 1.08-1.19, p < 0.001), but TOC was not associated. Similar results were found after excluding men with an incident fracture during follow-up. Higher ucOC and CTX were associated with CVD mortality (ucOC HR per 1 SD increase 1.13, 95% CI 1.05-1.22, p = 0.001; CTX HR = 1.12, 95% CI 1.04-1.20, p = 0.003), but this result was not significant in competing risks analysis. Higher CTX was also associated with cancer mortality (HR = 1.12, 95% CI 1.01-1.23, p = 0.024). In conclusion, in older men, higher bone turnover, assessed by BTMs including ucOC, is a biomarker for all-cause mortality risk. Undercarboxylated osteocalcin was a more informative biomarker for this outcome than TOC. Higher CTX was associated with all-cause and cancer-related mortality. Further evaluation of causality and potential underlying mechanisms is warranted. © 2022 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Prevalence and Risk Factors of Neurologic Manifestations in Hospitalized Children Diagnosed with Acute SARS-CoV-2 or MIS-C

BACKGROUND

Our objective was to characterize the frequency, early impact, and risk factors for neurological manifestations in hospitalized children with acute severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or multisystem inflammatory syndrome in children (MIS-C).

METHODS

Multicenter, cross-sectional study of neurological manifestations in children aged <18 years hospitalized with positive SARS-CoV-2 test or clinical diagnosis of a SARS-CoV-2-related condition between January 2020 and April 2021. Multivariable logistic regression to identify risk factors for neurological manifestations was performed.

RESULTS

Of 1493 children, 1278 (86%) were diagnosed with acute SARS-CoV-2 and 215 (14%) with MIS-C. Overall, 44% of the cohort (40% acute SARS-CoV-2 and 66% MIS-C) had at least one neurological manifestation. The most common neurological findings in children with acute SARS-CoV-2 and MIS-C diagnosis were headache (16% and 47%) and acute encephalopathy (15% and 22%), both P < 0.05. Children with neurological manifestations were more likely to require intensive care unit (ICU) care (51% vs 22%), P < 0.001. In multivariable logistic regression, children with neurological manifestations were older (odds ratio [OR] 1.1 and 95% confidence interval [CI] 1.07 to 1.13) and more likely to have MIS-C versus acute SARS-CoV-2 (OR 2.16, 95% CI 1.45 to 3.24), pre-existing neurological and metabolic conditions (OR 3.48, 95% CI 2.37 to 5.15; and OR 1.65, 95% CI 1.04 to 2.66, respectively), and pharyngeal (OR 1.74, 95% CI 1.16 to 2.64) or abdominal pain (OR 1.43, 95% CI 1.03 to 2.00); all P < 0.05.

CONCLUSIONS

In this multicenter study, 44% of children hospitalized with SARS-CoV-2-related conditions experienced neurological manifestations, which were associated with ICU admission and pre-existing neurological condition. Posthospital assessment for, and support of, functional impairment and neuroprotective strategies are vitally needed.

Understanding Traumatic Brain Injury in Females: A State-of-the-Art Summary and Future Directions

In this report, we identify existing issues and challenges related to research on traumatic brain injury (TBI) in females and provide future directions for research. In 2017, the National Institutes of Health, in partnership with the Center for Neuroscience and Regenerative Medicine and the Defense and Veterans Brain Injury Center, hosted a workshop that focused on the unique challenges facing researchers, clinicians, patients, and other stakeholders regarding TBI in women. The goal of this "Understanding TBI in Women" workshop was to bring together researchers and clinicians to identify knowledge gaps, best practices, and target populations in research on females and/or sex differences within the field of TBI. The workshop, and the current literature, clearly highlighted that females have been underrepresented in TBI studies and clinical trials and have often been excluded (or ovariectomized) in preclinical studies. Such an absence in research on females has led to an incomplete, and perhaps inaccurate, understanding of TBI in females. The presentations and discussions centered on the existing knowledge regarding sex differences in TBI research and how these differences could be incorporated in preclinical and clinical efforts going forward. Now, a little over 2 years later, we summarize the issues and state of the science that emerged from the "Understanding TBI in Women" workshop while incorporating updates where they exist. Overall, despite some progress, there remains an abundance of research focused on males and relatively little explicitly on females.

The Global Consortium Study of Neurological Dysfunction in COVID-19 (GCS-NeuroCOVID): Development of Case Report Forms for Global Use

Since its original report in January 2020, the coronavirus disease 2019 (COVID-19) due to Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) infection has rapidly become one of the deadliest global pandemics. Early reports indicate possible neurological manifestations associated with COVID-19, with symptoms ranging from mild to severe, highly variable prevalence rates, and uncertainty regarding causal or coincidental occurrence of symptoms. As neurological involvement of any systemic disease is frequently associated with adverse effects on morbidity and mortality, obtaining accurate and consistent global data on the extent to which COVID-19 may impact the nervous system is urgently needed. To address this need, investigators from the Neurocritical Care Society launched the Global Consortium Study of Neurological Dysfunction in COVID-19 (GCS-NeuroCOVID). The GCS-NeuroCOVID consortium rapidly implemented a Tier 1, pragmatic study to establish phenotypes and prevalence of neurological manifestations of COVID-19. A key component of this global collaboration is development and application of common data elements (CDEs) and definitions to facilitate rigorous and systematic data collection across resource settings. Integration of these elements is critical to reduce heterogeneity of data and allow for future high-quality meta-analyses. The GCS-NeuroCOVID consortium specifically designed these elements to be feasible for clinician investigators during a global pandemic when healthcare systems are likely overwhelmed and resources for research may be limited. Elements include pediatric components and translated versions to facilitate collaboration and data capture in Latin America, one of the epicenters of this global outbreak. In this manuscript, we share the specific data elements, definitions, and rationale for the adult and pediatric CDEs for Tier 1 of the GCS-NeuroCOVID consortium, as well as the translated versions adapted for use in Latin America. Global efforts are underway to further harmonize CDEs with other large consortia studying neurological and general aspects of COVID-19 infections. Ultimately, the GCS-NeuroCOVID consortium network provides a critical infrastructure to systematically capture data in current and future unanticipated disasters and disease outbreaks.

Global Consortium Study of Neurological Dysfunction in COVID-19 (GCS-NeuroCOVID): Study Design and Rationale

BACKGROUND

As the COVID-19 pandemic developed, reports of neurological dysfunctions spanning the central and peripheral nervous systems have emerged. The spectrum of acute neurological dysfunctions may implicate direct viral invasion, para-infectious complications, neurological manifestations of systemic diseases, or co-incident neurological dysfunction in the context of high SARS-CoV-2 prevalence. A rapid and pragmatic approach to understanding the prevalence, phenotypes, pathophysiology and prognostic implications of COVID-19 neurological syndromes is urgently needed.

METHODS

The Global Consortium to Study Neurological dysfunction in COVID-19 (GCS-NeuroCOVID), endorsed by the Neurocritical Care Society (NCS), was rapidly established to address this need in a tiered approach. Tier-1 consists of focused, pragmatic, low-cost, observational common data element (CDE) collection, which can be launched immediately at many sites in the first phase of this pandemic and is designed for expedited ethical board review with waiver-of-consent. Tier 2 consists of prospective functional and cognitive outcomes assessments with more detailed clinical, laboratory and radiographic data collection that would require informed consent. Tier 3 overlays Tiers 1 and 2 with experimental molecular, electrophysiology, pathology and imaging studies with longitudinal outcomes assessment and would require centers with specific resources. A multicenter pediatrics core has developed and launched a parallel study focusing on patients ages <18 years. Study sites are eligible for participation if they provide clinical care to COVID-19 patients and are able to conduct patient-oriented research under approval of an internal or global ethics committee. Hospitalized pediatric and adult patients with SARS-CoV-2 and with acute neurological signs or symptoms are eligible to participate. The primary study outcome is the overall prevalence of neurological complications among hospitalized COVID-19 patients, which will be calculated by pooled estimates of each neurological finding divided by the average census of COVID-19 positive patients over the study period. Secondary outcomes include: in-hospital, 30 and 90-day morality, discharge modified Rankin score, ventilator-free survival, ventilator days, discharge disposition, and hospital length of stay.

RESULTS

In a one-month period (3/27/20-4/27/20) the GCS-NeuroCOVID consortium was able to recruit 71 adult study sites, representing 17 countries and 5 continents and 34 pediatrics study sites.

CONCLUSIONS

This is one of the first large-scale global research collaboratives urgently assembled to evaluate acute neurological events in the context of a pandemic. The innovative and pragmatic tiered study approach has allowed for rapid recruitment and activation of numerous sites across the world-an approach essential to capture real-time critical neurological data to inform treatment strategies in this pandemic crisis.

Resuscitation with macromolecular superoxide dismutase/catalase mimetic polynitroxylated PEGylated hemoglobin offers neuroprotection in guinea pigs after traumatic brain injury combined with hemorrhage shock

Background

Polynitroxylated PEGylated hemoglobin (PNPH, aka SanFlow) possesses superoxide dismutase/catalase mimetic activities that may directly protect the brain from oxidative stress. Stabilization of PNPH with bound carbon monoxide prevents methemoglobin formation during storage and permits it to serve as a carbon monoxide donor. We determined whether small volume transfusion of hyperoncotic PNPH is neuroprotective in a polytrauma model of traumatic brain injury (TBI) plus hemorrhagic shock. Guinea pigs were used because, like humans, they do not synthesize their own ascorbic acid, which is important in reducing methemoglobin.

Results

TBI was produced by controlled cortical impact and was followed by 20 mL/kg hemorrhage to a mean arterial pressure (MAP) of 40 mmHg. At 90 min, animals were resuscitated with 20 mL/kg lactated Ringer’s solution or 10 mL/kg PNPH. Resuscitation with PNPH significantly augmented the early recovery of MAP after hemorrhagic shock by 10–18 mmHg; whole blood methemoglobin was only 1% higher and carboxyhemoglobin was 2% higher. At 9 days of recovery, unbiased stereology analysis revealed that, compared to animals resuscitated with lactated Ringer’s solution, those treated with PNPH had significantly more viable neurons in the hippocampus CA1 + 2 region (59 ± 10% versus 87 ± 18% of sham and naïve mean value) and in the dentate gyrus (70 ± 21% versus 96 ± 24%; n = 12 per group).

Conclusion

PNPH may serve as a small-volume resuscitation fluid for polytrauma involving TBI and hemorrhagic shock. The neuroprotection afforded by PNPH seen in other species was sustained in a species without endogenous ascorbic acid synthesis, thereby supporting potential translatability for human use.

Administration of a 20-Hydroxyeicosatetraenoic Acid Synthesis Inhibitor Improves Outcome in a Rat Model of Pediatric Traumatic Brain Injury

The arachidonic acid pathway metabolite 20-hydroxyeicosatetraenoic acid (20-HETE) contributes to ischemia/reperfusion brain injury. Inhibition of 20-HETE formation can protect the developing brain from global ischemia. Here, we examined whether treatment with the 20-HETE synthesis inhibitor N-hydroxy-N-4-butyl-2-methylphenylformamidine (HET0016) can protect the immature brain from traumatic brain injury (TBI). Male rats at postnatal day 9-10 underwent controlled cortical impact followed by intraperitoneal injection with vehicle or HET0016 (1 mg/kg, 5 min and 3 h post-injury). HET0016 decreased the lesion volume by over 50% at 3 days of recovery, and this effect persisted at 30 days as the brain matured. HET0016 decreased peri-lesion gene expression of proinflammatory cytokines (tumor necrosis factor-α [TNF-α], interleukin-1β [IL-1β]) at 1 day and increased reparative cytokine (IL-4, IL-10) expression at 3 days. It also partially preserved microglial ramified processes, consistent with less activation. HET0016 decreased contralateral hindlimb foot faults and improved outcome on the novel object recognition memory task 30 days after TBI. In cultured BV2 microglia, HET0016 attenuated the lipopolysaccharide-evoked increase in release of TNF-α. Our data show that HET0016 improves acute and long-term histologic and functional outcomes, in association with an attenuated neuroinflammatory response after contusion of an immature rat brain.

Sex differences in pediatric traumatic brain injury

The response of the developing brain to traumatic injury is different from the response of the mature, adult brain. There are critical developmental trajectories in the young brain, whereby injury can lead to long term functional abnormalities. Emerging preclinical and clinical literature supports the presence of significant sex differences in both the response to and the recovery from pediatric traumatic brain injury (TBI). These sex differences are seen at all pediatric ages, including neonates/infants, pre-pubertal children, and adolescents. As importantly, the response to neuroprotective therapies or treatments can differ between male and females subjects. These sex differences can result from several biologic origins, and may manifest differently during the various phases of brain and body development. Recognizing and understanding these potential sex differences is crucial, and should be considered in both preclinical and clinical studies of pediatric TBI.

Coumestrol Confers Partial Resistance in Soybean Plants Against Cercospora Leaf Blight

Although previous research showed that the purple symptom of Cercospora leaf blight (CLB) is associated with lower biomass of Cercospora cf. flagellaris and lower concentrations of cercosporin, a reactive oxygen species producer, as compared with blighted leaves, the hypothesis that the purple symptom is a plant reaction to the pathogen has never been tested. In this study, we demonstrated that high levels of coumestrol (COU) were associated with purple symptoms of CLB and that COU has strong antioxidant activity. Additionally, we found that COU is restricted to the pigmented areas of purple leaves, and the pigmentation is restricted to the adaxial surfaces, suggesting that COU may be acting as a sunscreen. Even though COU is associated with the purple leaf symptom, this coumestan is not the direct cause of discoloration in that COU is colorless. Quantification of chlorophyll a and b and total carotenoids suggested that blighted but not purple or asymptomatic leaves were undergoing photooxidative stress. Because the purple symptom is associated with high COU concentrations, lower biomass of C. cf. flagellaris, and lower cercosporin concentrations, we conclude that the purple symptom is a disease resistance reaction, mediated in part by COU, which provides a high level of antioxidant activity and, hence, partial resistance.

The epilepsy bioinformatics study for anti-epileptogenic therapy (EpiBioS4Rx) clinical biomarker: Study design and protocol

The Epilepsy Bioinformatics Study for Anti-epileptogenic Therapy (EpiBioS4Rx) is a longitudinal prospective observational study funded by the National Institute of Health (NIH) to discover and validate observational biomarkers of epileptogenesis after traumatic brain injury (TBI). A multidisciplinary approach has been incorporated to investigate acute electrical, neuroanatomical, and blood biomarkers after TBI that may predict the development of post-traumatic epilepsy (PTE). We plan to enroll 300 moderate-severe TBI patients with a frontal and/or temporal lobe hemorrhagic contusion. Acute evaluation with blood, imaging and electroencephalographic monitoring will be performed and then patients will be tracked for 2 years to determine the incidence of PTE. Validation of selected biomarkers that are discovered in planned animal models will be a principal feature of this work. Specific hypotheses regarding the discovery of biomarkers have been set forth in this study. An international cohort of 13 centers spanning 2 continents will be developed to facilitate this study, and for future interventional studies.

Metabolic Alterations in Developing Brain After Injury: Knowns and Unknowns

Brain development is a highly orchestrated complex process. The developing brain utilizes many substrates including glucose, ketone bodies, lactate, fatty acids and amino acids for energy, cell division and the biosynthesis of nucleotides, proteins and lipids. Metabolism is crucial to provide energy for all cellular processes required for brain development and function including ATP formation, synaptogenesis, synthesis, release and uptake of neurotransmitters, maintaining ionic gradients and redox status, and myelination. The rapidly growing population of infants and children with neurodevelopmental and cognitive impairments and life-long disability resulting from developmental brain injury is a significant public health concern. Brain injury in infants and children can have devastating effects because the injury is superimposed on the high metabolic demands of the developing brain. Acute injury in the pediatric brain can derail, halt or lead to dysregulation of the complex and highly regulated normal developmental processes. This paper provides a brief review of metabolism in developing brain and alterations found clinically and in animal models of developmental brain injury. The metabolic changes observed in three major categories of injury that can result in life-long cognitive and neurological disabilities, including neonatal hypoxia-ischemia, pediatric traumatic brain injury, and brain injury secondary to prematurity are reviewed.

Metabolic Alterations in Developing Brain After Injury: Knowns and Unknowns

Brain development is a highly orchestrated complex process. The developing brain utilizes many substrates including glucose, ketone bodies, lactate, fatty acids and amino acids for energy, cell division and the biosynthesis of nucleotides, proteins and lipids. Metabolism is crucial to provide energy for all cellular processes required for brain development and function including ATP formation, synaptogenesis, synthesis, release and uptake of neurotransmitters, maintaining ionic gradients and redox status, and myelination. The rapidly growing population of infants and children with neurodevelopmental and cognitive impairments and life-long disability resulting from developmental brain injury is a significant public health concern. Brain injury in infants and children can have devastating effects because the injury is superimposed on the high metabolic demands of the developing brain. Acute injury in the pediatric brain can derail, halt or lead to dysregulation of the complex and highly regulated normal developmental processes. This paper provides a brief review of metabolism in developing brain and alterations found clinically and in animal models of developmental brain injury. The metabolic changes observed in three major categories of injury that can result in life-long cognitive and neurological disabilities, including neonatal hypoxia-ischemia, pediatric traumatic brain injury, and brain injury secondary to prematurity are reviewed.

Development of a Quantitative Polymerase Chain Reaction Detection Protocol for Cercospora kikuchii in Soybean Leaves and Its Use for Documenting Latent Infection as Affected by Fungicide Applications

Cercospora leaf blight (CLB) of soybean, caused by Cercospora kikuchii, is a serious disease in the southern United States. A sensitive TaqMan probe-based real-time quantitative polymerase chain reaction (qPCR) assay was developed to specifically detect and quantify C. kikuchii in naturally infected soybean plants. The sensitivity was 1 pg of genomic DNA, which was equivalent to about 34 copies of genome of C. kikuchii. Using this qPCR assay, we documented a very long latent infection period for C. kikuchii in soybean leaves beginning at the V3 growth stage (as early as 22 days after planting). The levels of biomass of C. kikuchii remained low until R1, and a rapid increase was detected from the R2/R3 to R4/R5 growth stages shortly before the appearance of symptoms at R6. The efficacy of various fungicide regimens under field conditions also was evaluated over a 3-year period using this qPCR method. Our results showed that multiple fungicide applications beginning at R1 until late reproductive stages suppressed the development of C. kikuchii in leaves and delayed symptom expression. Different fungicide chemistries also had differential effects on the amount of latent infection and symptom expression during late reproductive growth stages.

Cerebral glucose metabolism in an immature rat model of pediatric traumatic brain injury

Altered cerebral metabolism and mitochondrial function have been identified in experimental and clinical studies of pediatric traumatic brain injury (TBI). Metabolic changes detected using (1)H (proton) magnetic resonance spectroscopy correlate with long-term outcomes in children after severe TBI. We previously identified early (4-h) and sustained (24-h and 7-day) abnormalities in brain metabolites after controlled cortical impact (CCI) in immature rats. The current study aimed to identify specific alterations of cerebral glucose metabolism at 24 h after TBI in immature rats. Rats (postnatal days 16-18) underwent CCI to the left parietal cortex. Sham rats underwent craniotomy only. Twenty-four hours after CCI, rats were injected (intraperitoneally) with [1,6-(13)C]glucose. Brains were removed, separated into hemispheres, and frozen. Metabolites were extracted with perchloric acid and analyzed using (1)H and (13)C-nuclear magnetic resonance spectroscopy. TBI resulted in decreases in N-acetylaspartate in both hemispheres, compared to sham contralateral. At 24 h after TBI, there was significant decrease in the incorporation of (13)C label into [3-(13)C]glutamate and [2-(13)C]glutamate in the injured brain. There were no differences in percent enrichment of [3-(13)C]glutamate, [4-(13)C]glutamate, [3-(13)C]glutamine, or [4-(13)C]glutamine. There was significantly lower percent enrichment of [2-(13)C]glutamate in both TBI sides and the sham craniotomy side, compared to sham contralateral. No differences were detected in enrichment of (13)C glucose label in [2-(13)C]glutamine, [2-(13)C]GABA (gamma-aminobutyric acid), [3-(13)C]GABA, or [4-(13)C]GABA, [3-(13)C]lactate, or [3-(13)C]alanine between groups. Results suggest that overall oxidative glucose metabolism in the immature brain recovers at 24 h after TBI. Specific reductions in [2-(13)C]glutamate could be the result of impairments in either neuronal or astrocytic metabolism. Future studies should aim to identify pathways leading to decreased metabolism and develop cell-selective "metabolic rescue."

Prenatal exposure to psychostimulants increases impulsivity, compulsivity, and motivation for rewards in adult mice

Given the widespread use and misuse of methamphetamine (METH) and methylphenidate (MPD), especially in relation to women of childbearing age, it is important to consider the long-lasting effects of these drugs on the brain of the developing fetus. Male and female C57Bl/6J mice were prenatally exposed to METH (5mg/kg), MPD (10mg/kg), or saline. Following a 3-month washout, behavioral analysis using the 5-Choice Serial Reaction Time Task (5CSRTT) was performed on adult mice. After reaching training criteria, performance on a pseudo-random intertrial interval test session revealed decrements in 5CSRTT behavior. Prenatally-treated METH and MPD mice demonstrated significant increases in impulsivity, compulsivity, and motivation for reward compared to their saline controls. There were sex by drug interactions indicating a possible sexually dimorphic response to these prenatal drug exposures. Of particular clinical interest, we find that mice prenatally exposed to METH or MPD express characteristics of both inhibitory control decrements and heightened motivation for rewards, which represent core symptoms of addiction and other impulse control disorders.

Effects of Simplicillium lanosoniveum on Phakopsora pachyrhizi, the soybean rust pathogen, and its use as a biological control agent

The fungus Simplicillium lanosoniveum was isolated from soybean leaves infected with Phakopsora pachyrhizi, the soybean rust pathogen, in Louisiana and Florida. The fungus did not grow or become established on leaf surfaces until uredinia erupted, but when soybean rust signs and symptoms were evident, S. lanosoniveum colonized leaves within 3 days and sporulated within 4 days. Development of new uredinia was suppressed by about fourfold when S. lanosoniveum colonized uredinia. In the presence of S. lanosoniveum, uredinia became increasingly red-brown, and urediniospores turned brown and germinated at very low rates. Assays using quantitative real time polymerase chain reaction revealed that the fungus colonized leaf surfaces when plants were infected with P. pachyrhizi, either in a latent stage of infection or when symptoms were present. However, when plants were inoculated before infection, there was no increase of DNA of S. lanosoniveum, suggesting that the pathogen must be present in order for the antagonist to become established on soybean leaf surfaces. We documented significantly lower amounts of DNA of P. pachyrhizi and lower disease severity when soybean leaves were colonized with S. lanosoniveum. These studies documented the mycophilic and disease-suppressive nature of S. lanosoniveum.

Cyclosporin A preserves mitochondrial function after traumatic brain injury in the immature rat and piglet

Cyclosporin A (CsA) has been shown to be neuroprotective in mature animal models of traumatic brain injury (TBI), but its effects on immature animal models of TBI are unknown. In mature animal models, CsA inhibits the opening of the mitochondrial permeability transition pore (MPTP), thereby maintaining mitochondrial homeostasis following injury by inhibiting calcium influx and preserving mitochondrial membrane potential. The aim of the present study was to evaluate CsA's ability to preserve mitochondrial bioenergetic function following TBI (as measured by mitochondrial respiration and cerebral microdialysis), in two immature models (focal and diffuse), and in two different species (rat and piglet). Three groups were studied: injured+CsA, injured+saline vehicle, and uninjured shams. In addition, we evaluated CsA's effects on cerebral hemodynamics as measured by a novel thermal diffusion probe. The results demonstrate that post-injury administration of CsA ameliorates mitochondrial dysfunction, preserves cerebral blood flow (CBF), and limits neuropathology in immature animals 24 h post-TBI. Mitochondria were isolated 24 h after controlled cortical impact (CCI) in rats and rapid non-impact rotational injury (RNR) in piglets, and CsA ameliorated cerebral bioenergetic crisis with preservation of the respiratory control ratio (RCR) to sham levels. Results were more dramatic in RNR piglets than in CCI rats. In piglets, CsA also preserved lactate pyruvate ratios (LPR), as measured by cerebral microdialysis and CBF at sham levels 24 h after injury, in contrast to the significant alterations seen in injured piglets compared to shams (p<0.01). The administration of CsA to piglets following RNR promoted a 42% decrease in injured brain volume (p<0.01). We conclude that CsA exhibits significant neuroprotective activity in immature models of focal and diffuse TBI, and has exciting translational potential as a therapeutic agent for neuroprotection in children.

Mitochondrial mechanisms of cell death and neuroprotection in pediatric ischemic and traumatic brain injury

There are several forms of acute pediatric brain injury, including neonatal asphyxia, pediatric cardiac arrest with global ischemia, and head trauma, that result in devastating, lifelong neurologic impairment. The only clinical intervention that appears neuroprotective is hypothermia initiated soon after the initial injury. Evidence indicates that oxidative stress, mitochondrial dysfunction, and impaired cerebral energy metabolism contribute to the brain cell death that is responsible for much of the poor neurologic outcome from these events. Recent results obtained from both in vitro and animal models of neuronal death in the immature brain point toward several molecular mechanisms that are either induced or promoted by oxidative modification of macromolecules, including consumption of cytosolic and mitochondrial NAD(+) by poly-ADP ribose polymerase, opening of the mitochondrial inner membrane permeability transition pore, and inactivation of key, rate-limiting metabolic enzymes, e.g., the pyruvate dehydrogenase complex. In addition, the relative abundance of pro-apoptotic proteins in immature brains and neurons, and particularly within their mitochondria, predisposes these cells to the intrinsic, mitochondrial pathway of apoptosis, mediated by Bax- or Bak-triggered release of proteins into the cytosol through the mitochondrial outer membrane. Based on these pathways of cell dysfunction and death, several approaches toward neuroprotection are being investigated that show promise toward clinical translation. These strategies include minimizing oxidative stress by avoiding unnecessary hyperoxia, promoting aerobic energy metabolism by repletion of NAD(+) and by providing alternative oxidative fuels, e.g., ketone bodies, directly interfering with apoptotic pathways at the mitochondrial level, and pharmacologic induction of antioxidant and anti-inflammatory gene expression.

Early and sustained alterations in cerebral metabolism after traumatic brain injury in immature rats

Although studies have shown alterations in cerebral metabolism after traumatic brain injury (TBI), clinical data in the developing brain is limited. We hypothesized that post-traumatic metabolic changes occur early (<24 h) and persist for up to 1 week. Immature rats underwent TBI to the left parietal cortex. Brains were removed at 4 h, 24 h, and 7 days after injury, and separated into ipsilateral (injured) and contralateral (control) hemispheres. Proton nuclear magnetic resonance (NMR) spectra were obtained, and spectra were analyzed for N-acetyl-aspartate (NAA), lactate (Lac), creatine (Cr), choline, and alanine, with metabolite ratios determined (NAA/Cr, Lac/Cr). There were no metabolic differences at any time in sham controls between cerebral hemispheres. At 4 and 24 h, there was an increase in Lac/Cr, reflecting increased glycolysis and/or decreased oxidative metabolism. At 24 h and 7 days, there was a decrease in NAA/Cr, indicating loss of neuronal integrity. The NAA/Lac ratio was decreased ( approximately 15-20%) at all times (4 h, 24 h, 7 days) in the injured hemisphere of TBI rats. In conclusion, metabolic derangements begin early (<24 h) after TBI in the immature rat and are sustained for up to 7 days. Evaluation of early metabolic alterations after TBI could identify novel targets for neuroprotection in the developing brain.

Normoxic ventilatory resuscitation following controlled cortical impact reduces peroxynitrite-mediated protein nitration in the hippocampus

OBJECTIVES

Ventilatory resuscitation with 100% O2 after severe traumatic brain injury (TBI) raises concerns about the increased production of reactive oxygen species (ROS). The product of peroxynitrite-meditated tyrosine residue nitration, 3-nitrotyrosine (3-NT), is a marker for oxidative damage to proteins. The authors hypothesized that posttraumatic resuscitation with hyperoxia (100% fraction of inspired oxygen [FiO2] concentration) results in increased ROS-induced damage to proteins compared with resuscitation using normoxia (21% FiO2 concentration).

METHODS

Male Sprague-Dawley rats underwent controlled cortical impact (CCI) injury and resuscitation with either normoxic or hyperoxic ventilation for 1 hour (5 rats per group). Twenty-four hours after injury, rat hippocampi were evaluated using 3-NT immunostaining. In a second experiment, animals similarly underwent CCI injury and normoxic or hyperoxic ventilation for 1 hour (4 rats per group). One week after injury, neuronal counts were performed after neuronal nuclei immunostaining.

RESULTS

The 3-NT staining was significantly increased in the hippocampi of the hyperoxic group. The normoxic group showed a 51.0% reduction of staining in the CA1 region compared with the hyperoxic group and a 50.8% reduction in the CA3 region (p < 0.05, both regions). There was no significant difference in staining between the injured normoxic group and sham-operated control groups. In the delayed analysis of neuronal survival (neuronal counts), there was no significant difference between the hyperoxic and normoxic groups.

CONCLUSIONS

In this clinically relevant model of TBI, normoxic resuscitation significantly reduced oxidative damage to proteins compared with hyperoxic resuscitation. Neuronal counts showed no benefit from hyperoxic resuscitation. These findings indicate that hyperoxic ventilation in the early stages after severe TBI may exacerbate oxidative damage to proteins.

Mitochondrial dysfunction early after traumatic brain injury in immature rats

Mitochondria play central roles in acute brain injury; however, little is known about mitochondrial function following traumatic brain injury (TBI) to the immature brain. We hypothesized that TBI would cause mitochondrial dysfunction early (<4 h) after injury. Immature rats underwent controlled cortical impact (CCI) or sham injury to the left cortex, and mitochondria were isolated from both hemispheres at 1 and 4 h after TBI. Rates of phosphorylating (State 3) and resting (State 4) respiration were measured with and without bovine serum albumin. The respiratory control ratio was calculated (State 3/State 4). Rates of mitochondrial H(2)O(2) production, pyruvate dehydrogenase complex enzyme activity, and cytochrome c content were measured. Mitochondrial State 4 rates (ipsilateral/contralateral ratios) were higher after TBI at 1 h, which was reversed with bovine serum albumin. Four hours after TBI, pyruvate dehydrogenase complex activity and cytochrome c content (ipsilateral/contralateral ratios) were lower in TBI mitochondria. These data demonstrate abnormal mitochondrial function early (<or=4 h) after TBI in the developing brain. Future studies directed at reversing mitochondrial abnormalities could guide neuroprotective interventions after pediatric TBI.

The potential role of mitochondria in pediatric traumatic brain injury

Mitochondria play a central role in cerebral energy metabolism, intracellular calcium homeostasis and reactive oxygen species generation and detoxification. Following traumatic brain injury (TBI), the degree of mitochondrial injury or dysfunction can be an important determinant of cell survival or death. Literature would suggest that brain mitochondria from the developing brain are very different from those from mature animals. Therefore, aspects of developmental differences in the mitochondrial response to TBI can make the immature brain more vulnerable to traumatic injury. This review will focus on four main areas of secondary injury after pediatric TBI, including excitotoxicity, oxidative stress, alterations in energy metabolism and cell death pathways. Specifically, we will describe what is known about developmental differences in mitochondrial function in these areas, in both the normal, physiologic state and the pathologic state after pediatric TBI. The ability to identify and target aspects of mitochondrial dysfunction could lead to novel neuroprotective therapies for infants and children after severe TBI.

Physiologic progesterone reduces mitochondrial dysfunction and hippocampal cell loss after traumatic brain injury in female rats

Growing literature suggests important sex-based differences in outcome following traumatic brain injury (TBI) in animals and humans. Progesterone has emerged as a key hormone involved in many potential neuroprotective pathways after acute brain injury and may be responsible for some of these differences. Many studies have utilized supraphysiologic levels of post-traumatic progesterone to reverse pathologic processes after TBI, but few studies have focused on the role of endogenous physiologic levels of progesterone in neuroprotection. We hypothesized that progesterone at physiologic serum levels would be neuroprotective in female rats after TBI and that progesterone would reverse early mitochondrial dysfunction seen in this model. Female, Sprague-Dawley rats were ovariectomized and implanted with silastic capsules containing either low or high physiologic range progesterone at 7 days prior to TBI. Control rats received ovariectomy with implants containing no hormone. Rats underwent controlled cortical impact to the left parietotemporal cortex and were evaluated for evidence of early mitochondrial dysfunction (1 h) and delayed hippocampal neuronal injury and cortical tissue loss (7 days) after injury. Progesterone in the low physiologic range reversed the early postinjury alterations seen in mitochondrial respiration and reduced hippocampal neuronal loss in both the CA1 and CA3 subfields. Progesterone in the high physiologic range had a more limited pattern of hippocampal neuronal preservation in the CA3 region only. Neither progesterone dose significantly reduced cortical tissue loss. These findings have implications in understanding the sex-based differences in outcome following acute brain injury.

Prospective assessment of guidelines for determining appropriate depth of endotracheal tube placement in children

OBJECTIVE

To determine whether multiplying the internal diameter of the endotracheal tube (ETT) by 3 (3x ETT size) is a reliable method for determining correct depth of oral ETT placement in the pediatric population.

DESIGN

Prospective, observational.

SETTING

University-affiliated, 12-bed pediatric intensive care unit.

PATIENTS

Orally intubated pediatric intensive care unit patients of < or =12 yrs of age.

INTERVENTIONS

Demographics, ETT size, and depth of ETT placement measured from the lip were obtained. Correct placement, defined as the tip of the ETT below the thoracic inlet and > or =0.5 cm above the carina, was determined by chest radiograph.

MEASUREMENTS AND MAIN RESULTS

Suggested ETT size based on the Pediatric Advanced Life Support (PALS) age-based formula and the Broselow tape-length-based guidelines were determined. A total of 174 of 226 ETTs (77%) were correctly positioned. If practitioners utilized the 3x ETT size for the actual tubes chosen, 170 of 226 (75%) would have been accurately placed. More accurate were the 3x PALS-based ETT size (81%) and 3x Broselow-suggested ETT size (85%). The use of the Broselow ETTs to determine the depth would have led to a significantly improved ETT position (p = .009) compared with the actual ETT.

CONCLUSION

The commonly used formula of 3x tube size for ETT depth in children results in 15-25% malpositioned tubes. Practitioners can improve the reliability of this formula by utilizing the recommended ETT size as suggested by the Broselow tape. A more reliable method is necessary to avoid ETT malposition.

Synthes Award for Resident Research on Brain and Craniofacial Injury: normoxic ventilatory resuscitation after controlled cortical impact reduces peroxynitrite-mediated protein nitration in the hippocampus

Resuscitation with 100% ventilatory oxygen is routinely initiated after severe traumatic brain injury (TBI). Despite the objective to improve oxygenation of the injured brain, there are concerns about the increased production of reactive oxygen species (ROS), which can lead to further neuronal damage. 3-nitrotyrosine (3-NT), the product of peroxynitrite-meditated tyrosine residue nitration, has been used as a marker for ROS-induced oxidative damage to proteins. We hypothesized that posttraumatic resuscitation with hyperoxic ventilation with a fraction of inspired oxygen (Fio2, 100%) results in increased ROS-induced damage to proteins compared with resuscitation with normoxic ventilation or room air (Fio2, 21%). Male Sprague-Dawley rats underwent controlled cortical impact (CCI) and were resuscitated with either normoxic or hyperoxic ventilation for 1 hour after injury (n = 5 per group). Sham-operated control groups received 1 hour of normoxic or hyperoxic ventilation without CCI (n = 4-5 per group). Twenty-four hours after injury, rats were perfused with fixative, and hippocampi were evaluated for levels of 3-NT immunostaining. In a second experiment, for a delayed assessment of neuronal survival, another set of rats similarly underwent CCI and normoxic or hyperoxic ventilation for 1 hour (n = 4 per group), and a sham-operated group was used as a control (n = 4). One week after injury, neuronal cell counts and abnormal cell quantification were performed after staining with the neuron-specific NeuN antibody. Quantification of 3-NT staining revealed significantly increased levels in the ipsilateral hippocampus in the hyperoxic CCI group. The normoxic group showed a 51.0% reduction of staining in CA1 when compared with those rats resuscitated with hyperoxia and a 50.8% reduction in CA3 (both P < 0.05). There was no significant difference in staining between the injured normoxic group and the sham-operated groups. In the delayed analysis of neuronal survival, although neuronal counts were reduced in the hippocampus on the injured side in both injured groups, there was no significant difference between hyperoxic and normoxic groups. Similarly, abnormal cell counts were not significantly different between groups.

Mitochondrial Dysfunction Contributes to Cell Death Following Traumatic Brain Injury in Adult and Immature Animals

Secondary injury following traumatic brain injury (TBI) is characterized by a variety of pathophysiologic cascades. Many of these cascades can have significant detrimental effects on cerebral mitochondria. These include exposure of neurons to excitotoxic levels of excitatory neurotransmitters with intracellular calcium influx, generation of reactive oxygen species, and production of peptides that participate in apoptotic cell death. Both experimental and clinical TBI studies have documented mitochondrial dysfunction, and animal studies suggest this dysfunction begins early and may persist for days following injury. Furthermore, interventions targeting mitochondrial mechanisms have shown neuroprotection after TBI. Continued evaluation and understanding of mitochondrial mechanisms contributing to neuronal cell death and survival after TBI is indicated. In addition, important underlying factors, such as brain maturation, that influence mitochondrial function should be studied. The ability to identify, target, and manipulate mitochondrial dysfunction may lead to the development of novel therapies for the treatment of adult and pediatric TBI.

Mitochondrial response to calcium in the developing brain

Developmental differences in mitochondrial content and metabolic enzyme activities have been defined, but less is understood about the responses of brain mitochondria to stressful stimuli during development. Cerebral mitochondrial response to high Ca(2+) loads after brain injury is a critical determinant of neuronal outcome. Brain mitochondria isolated from 16-18-day-old rats had lower maximal, respiration-dependent Ca(2+) uptake capacity than brain mitochondria isolated from adult rats in the presence of ATP at both a pH of 7.0 and 6.5. However, in the absence of ATP, immature brain mitochondria exhibited greater Ca(2+) uptake capacity at pH 7.0 and 6.5, indicating a greater resistance of immature brain mitochondria to Ca(2+)-induced dysfunction under conditions relevant to those that exist during acute ischemic and traumatic brain injury. Acidosis reduced the maximal Ca(2+) uptake capacity in both immature and adult brain mitochondria. Cytochrome c was released from both immature and adult brain mitochondria in response to Ca(2+) exposure, but was not affected by cyclosporin A, an inhibitor of the mitochondrial membrane permeability transition. Developmental changes in mitochondrial response to Ca(2+) loads may have important implications in the pathobiology of brain injury to the developing brain.

Postnatal brain development and neural cell differentiation modulate mitochondrial Bax and BH3 peptide-induced cytochrome c release

Bax mediates cytochrome c release and apoptosis during neurodevelopment. Brain mitochondria that were isolated from 8-day, 17-day, and adult rats displayed decreasing levels of mitochondrial Bax. The amount of cytochrome c released from brain mitochondria by a peptide containing the BH3 cell death domain decreased with increasing age. However, approximately 60% of cytochrome c in adult brain mitochondria could be released by the BH3 peptide in the presence of exogenous human recombinant Bax. Mitochondrial Bax was downregulated in PC12S neural cells differentiated with nerve growth factor, and mitochondria isolated from these cells demonstrated decreased sensitivity to BH3-peptide-induced cytochrome c release. These results demonstrate that immature brain mitochondria and mitochondria from undifferentiated neural cells are particularly sensitive to cytochrome c release mediated by endogenous Bax and a BH3 death domain peptide. Postnatal developmental changes in mitochondrial Bax levels may contribute to the increased susceptibility of neurons to pathological apoptosis in immature animals.

Increased adenosine in cerebrospinal fluid after severe traumatic brain injury in infants and children: association with severity of injury and excitotoxicity

OBJECTIVES

To measure adenosine concentration in the cerebrospinal fluid of infants and children after severe traumatic brain injury and to evaluate the contribution of patient age, Glasgow Coma Scale score, mechanism of injury, Glasgow Outcome Score, and time after injury to cerebrospinal fluid adenosine concentrations. To evaluate the relationship between cerebrospinal fluid adenosine and glutamate concentrations in this population.

DESIGN

Prospective survey.

SETTING

Pediatric intensive care unit in a university-based children's hospital.

PATIENTS

Twenty-seven critically ill infants and children who had severe traumatic brain injury (Glasgow Coma Scale < 8), who required placement of an intraventricular catheter and drainage of cerebrospinal fluid as part of their neurointensive care.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients ranged in age from 2 months to 14 yrs. Cerebrospinal fluid samples (n = 304) were collected from 27 patients during the first 7 days after traumatic brain injury. Control cerebrospinal fluid samples were obtained from lumbar puncture on 21 infants and children without traumatic brain injury or meningitis. Adenosine concentration was measured by using high-pressure liquid chromatography. Adenosine concentration was increased markedly in cerebrospinal fluid of children after traumatic brain injury vs. controls (p < .001). The increase in cerebrospinal fluid adenosine was independently associated with Glasgow Coma Scale < or = 4 vs. > 4 and time after injury (both p < .005). Cerebrospinal fluid adenosine concentration was not independently associated with either age (< or = 4 vs. > 4 yrs), mechanism of injury (abuse vs. other), or Glasgow Outcome Score (good/moderately disabled vs. severely disabled, vegetative, or dead). Of the 27 patients studied, 18 had cerebrospinal fluid glutamate concentration previously quantified by high-pressure liquid chromatography. There was a strong association between increases in cerebrospinal fluid adenosine and glutamate concentrations (p < .005) after injury.

CONCLUSIONS

Cerebrospinal fluid adenosine concentration is increased in a time- and severity-dependent manner in infants and children after severe head injury. The association between cerebrospinal fluid adenosine and glutamate concentrations may reflect an endogenous attempt at neuroprotection against excitotoxicity after severe traumatic brain injury.

Increased adrenomedullin in cerebrospinal fluid after traumatic brain injury in infants and children

Adrenomedullin is a recently discovered 52-amino acid peptide that is a potent vasodilator and is produced in the brain in experimental models of cerebral ischemia. Infusion of adrenomedullin increases regional cerebral blood flow and reduces infarct volume after vascular occlusion in rats, and thus may represent an endogenous neuroprotectant. Disturbances in cerebral blood flow (CBF), including hypoperfusion and hyperemia, frequently occur after severe traumatic brain injury (TBI) in infants and children. We hypothesized that cerebrospinal fluid (CSF) adrenomedullin concentration would be increased after severe TBI in infants and children, and that increases in adrenomedullin would be associated with alterations in CBF. We also investigated whether posttraumatic CSF adrenomedullin concentration was associated with relevant clinical variables (CBF, age, Glasgow Coma Scale [GCS] score, mechanism of injury, and outcome). Total adrenomedullin concentration was measured using a radioimmunometric assay. Sixty-six samples of ventricular CSF from 21 pediatric patients were collected during the first 10 days after severe TBI (GCS score < 8). Control CSF was obtained from children (n = 10) undergoing lumbar puncture without TBI or meningitis. Patients received standard neurointensive care, including CSF drainage. CBF was measured using Xenon computed tomography (CT) in 11 of 21 patients. Adrenomedullin concentration was markedly increased in CSF of infants and children after severe TBI vs control (median 4.5 versus 1.0 fmol/mL, p < 0.05). Sixty-two of 66 CSF samples (93.9%) from head-injured infants and children had a total adrenomedullin concentration that was greater than the median value for controls. Increases in CSF adrenomedullin were most commonly observed early after TBI. CBF was positively correlated with CSF adrenomedullin concentration (p < 0.001), but this relationship was not significant when controlling for the effect of time. CSF adrenomedullin was not significantly associated with other selected clinical variables. We conclude adrenomedullin is markedly increased in the CSF of infants and children early after severe TBI. We speculate that adrenomedullin participates in the regulation of CBF after severe TBI.

Assessment of 2-chloroadenosine treatment after experimental traumatic brain injury in the rat using arterial spin-labeled MRI: a preliminary report

Adenosine is a putative endogenous neuroprotectant. Its action at A1 receptors mitigates excitotoxicity while action at A2 receptors increases cerebral blood flow (CBF). We hypothesized that cerebral injection of the adenosine analog, 2-chloroadenosine, would decrease swelling and increase CBF early after experimental traumatic brain injury (TBI). To test this hypothesis, rats were anesthetized and subjected to TBI using a controlled cortical impact (CCI) model (n = 5/group). Immediately after injury, 2-chloroadenosine (0.3 nmole in 2 microliters) or an equal volume of vehicle were stereotactically injected lateral to the area of contusion. Using magnetic resonance imaging (MRI), in vivo spin-lattice relaxation time of tissue water (Tlobs) and CBF (arterial spin labeling) were measured in a 2-mm thick slice in the injured and non-injured hemispheres at 3-4 h after CCI. In a separate, preliminary experiment, the effect of 2-chloroadenosine injection in normal rat brain was studied. Rats (n = 2) were anesthetized and a burr hole was made for injection of 2-chloroadenosine into the same site as in the TBI model. One rat received the standard dose of 0.3 nmole and one rat received a 6 nmole injection. Tlobs and CBF studies were obtained 1.5-3.5 h after injection, using the same MRI methods as in the TBI study. In rats subjected to TBI, treatment with 2-chloroadenosine attenuated the increase in Tlobs after injury (p < 0.05 for treatment vs vehicle) in both hippocampus and cortex ipsilateral to injury. However, treatment with 2-chloroadenosine did not improve post-traumatic hypoperfusion. In normal rats, injection of 0.3 nmole of 2-chloroadenosine did not increase CBF, but the higher dosage of 6 nmole dramatically increased hemispheric CBF by 1.5-2.0-fold. The effect of local injection of 2-chloroadenosine at a dose of 0.3 nmole after experimental TBI on Tlobs presumably represents a reduction in post-traumatic edema. This reduction in edema, along with the augmentation of CBF seen in normal rats at higher dosage (6 nmole), supports a role for adenosine in neuroprotection following TBI.

Increased adrenomedullin in cerebrospinal fluid after traumatic brain injury in children: a preliminary report

Adrenomedullin is a recently discovered 52-amino-acid peptide that is a potent vasodilator. Infusion of adrenomedullin increases regional cerebral blood flow and reduces infarct volume after vascular occlusion in rats. Adrenomedullin may represent an endogenous neuroprotectant since it is increased after focal brain ischemia. Cerebral hypoperfusion is present after traumatic brain injury (TBI) in children. We hypothesized that adrenomedullin levels would be increased in children with severe TBI. Total adrenomedullin concentrations were measured using a radioimmunometric assay. Thirty-six samples of ventricular cerebrospinal fluid (CSF) from 10 pediatric patients were collected during the first 10 days after severe TBI (GCS < 8). Control CSF was obtained from 5 children undergoing lumbar puncture, who had normal CSF parameters and no evidence of central nervous system infection. Patients underwent standard neuro-intensive care, including cerebrospinal fluid drainage. Data were analyzed using a univariate regression model. Adrenomedullin concentration was markedly elevated in CSF of children following TBI versus control (mean level 10.65 vs 1.51 fmol/ml, p = 0.006). All 36 case samples had an adrenomedullin concentration above the median value for the controls (1.52 fmol/ml). We conclude adrenomedullin is elevated in the CSF of children following severe TBI. We speculate that it participates in the endogenous response to cerebral hypoperfusion after TBI.

Assessment of the effect of 2-chloroadenosine in normal rat brain using spin-labeled MRI measurement of perfusion

Adenosine analogs such as 2-chloroadenosine are potent cerebrovasodilators. Spin-labeled MRI was used to investigate the spatial distribution, dose-response, and timing of the effect of 2-chloroadenosine on cerebral blood flow (CBF) after intraparenchymal injection into rat brain. Sprague-Dawley rats (N = 10) were injected with 2-chloroadenosine at doses of 0.3, 6.0, or 12 nmoles, or saline vehicle (2-4 microL). CBF was serially quantified in a slice through the injection site in a circular (3.6 mm diameter) region of interest (ROI) around the injection and in ipsilateral hemispheric ROIs at approximately 90 min and approximately 180 min. Marked 3.77- and 3.93-fold increases in CBF (vs. vehicle) were seen in the circular ROI at approximately 90 min and approximately 180 min after 12-nmol injection, respectively. Similarly, 2.92- and 2.78-fold increases in hemispheric CBF were observed at approximately 90 min and approximately 180 min, respectively, after injection of 12 nmoles. Linear dose-response relationships were observed at both times after injection in both ROIs (all P < 0.01). Spin-labeling MRI assessment revealed that parenchymal injection of 2-chloroadenosine produces potent, dose-dependent, and sustained vasodilation over large areas of brain. This treatment and imaging paradigm should facilitate investigation of the effect of CBF promotion in models of traumatic and ischemic brain injury.

No long-term benefit from hypothermia after severe traumatic brain injury with secondary insult in rats

OBJECTIVES

To evaluate the effect of application of transient, moderate hypothermia on outcome after experimental traumatic brain injury (TBI) with a secondary hypoxemic insult.

DESIGN

Prospective, randomized study.

SETTING

University-based animal research facility.

SUBJECTS

Male Sprague-Dawley rats.

INTERVENTIONS

All rats were subjected to severe TBI followed by 30 mins of moderate hypoxemia, associated with mild hypotension. Rats were randomized to three groups: a) normothermia (37 degrees C + 0.5 degrees C); b) immediate hypothermia (32 degrees C +/- 0.5 degrees C initiated after trauma, before hypoxemia); and c) delayed hypothermia (32 degrees C +/- 0.5 degrees C after hypoxemia). The brain temperature was controlled for 4 hrs after TBI and hypoxemia.

MEASUREMENTS AND MAIN RESULTS

Animals were evaluated after TBI for motor and cognitive performance using beam balance (days 1-5 after TBI), beam walking (days 1-5 after TBI), and Morris Water Maze (days 14-18 after TBI) assessments. On day 21 after TBI, rats were perfused with paraformaldehyde and brains were histologically evaluated for lesion volume and hippocampal neuron counts. All three groups showed marked deficits in beam balance, beam walking, and Morris Water Maze performance. However, these deficits did not differ between groups. There was no difference in lesion volume between groups. All animals had significant hippocampal neuronal loss on the side ipsilateral to injury, but this loss was similar between groups.

CONCLUSIONS

In this rat model of severe TBI with secondary insult, moderate hypothermia for 4 hrs posttrauma failed to improve motor function, cognitive function, lesion volume or hippocampal neuronal survival. Combination therapies may be necessary in this difficult setting.

Biochemical, cellular, and molecular mechanisms in the evolution of secondary damage after severe traumatic brain injury in infants and children: Lessons learned from the bedside

OBJECTIVE: To present a state-of-the-art review of mechanisms of secondary injury in the evolution of damage after severe traumatic brain injury in infants and children. DATA SOURCES: We reviewed 152 peer-reviewed publications, 15 abstracts and proceedings, and other material relevant to the study of biochemical, cellular, and molecular mechanisms of damage in traumatic brain injury. Clinical studies of severe traumatic brain injury in infants and children were the focus, but reports in experimental models in immature animals were also considered. Results from both clinical studies in adults and models of traumatic brain injury in adult animals were presented for comparison. DATA SYNTHESIS: Categories of mechanisms defined were those associated with ischemia, excitotoxicity, energy failure, and resultant cell death cascades; secondary cerebral swelling; axonal injury; and inflammation and regeneration. CONCLUSIONS: A constellation of mediators of secondary damage, endogenous neuroprotection, repair, and regeneration are set into motion in the brain after severe traumatic injury. The quantitative contribution of each mediator to outcome, the interplay between these mediators, and the integration of these mechanistic findings with novel imaging methods, bedside physiology, outcome assessment, and therapeutic intervention remain an important target for future research.

Learned helplessness in Drosophila melanogaster?

Drosophila ( n = 11) exposed to inescapable mechanical shaking in a black-white Y-maze escape task had reliably longer escape latencies 12 hr. later in a black-white shuttlebox escape task than groups ( ns = 11) with escapable shaking or without (control).

A private breast imaging practice: medical audit of 25,788 screening and 1,077 diagnostic examinations

During 1989 and 1990, 25,788 screening and 1,077 diagnostic breast imaging examinations were performed. Audit was performed in 6-month intervals to allow comparison of performance over time. Sensitivity, positive predictive value, and stage of disease were determined for each radiologist, for patients over and those under 50 years of age, and for patients with and for those without a suspect palpable breast abnormality. In the screening portion of the study, 1,539 of 25,788 (5.9%) patients were asked to return for diagnostic breast imaging, 119 of 188 (63%) cancers were stage 0 or stage 1 disease, and a sensitivity of 91% and a positive predictive value of 11% were found. If patients with a palpable breast abnormality were eliminated, 103 of 138 (75%) patients had disease that was less than stage 2. In the diagnostic portion of the study, 296 of 1,077 (27%) patients were referred for biopsy and 53 of 71 (75%) cancers were stage 0 or stage 1 disease. A sensitivity of 97% and a positive predictive value of 24% were found. If patients with a palpable breast abnormality were eliminated, 51 of 63 (81%) patients had disease that was less than stage 2.

Nonpalpable lesions in the augmented breast: preoperative localization

Special compression views of the breast were used to detect suspect lesions in eight women who had undergone augmentation mammoplasty. Hook-wire localization with the use of these views proved safe and accurate for preoperative localization in these women, one of whom had a very small cancer.

Improved control of image optical density with low-dose digital and conventional radiography in bedside imaging

The technical and diagnostic performance of simultaneously acquired low-dose (44% of standard dose) storage-phosphor digital radiographs (system resolution = 0.2 mm, 10 bits) were compared with those of standard-dose conventional bedside radiographs of the chest in 32 patients. The mean optical density (OD) of the lungs (800 measurements) was closer to the ideal density with digital radiography (1.45 OD +/- 0.20 [standard deviation] vs 1.75 OD +/- 0.53) and was less often outside the usable range (2.5% vs 42.5%). Receiver operating characteristic analysis for detection of simulated nodules and monitoring devices (nine readers, 4,608 observations) showed that digital radiography was superior to conventional radiography (P less than .05) for four of the nine readers and equivalent to conventional radiography for five readers. The authors concluded that digital radiography produces more consistent and ideal image density and performs at least as well as conventional radiography under phantom test conditions.

Communication problems after mammographic screening

The authors prospectively assessed the effectiveness of requests for immediate additional evaluation or biopsy made on the basis of the interpretation of abnormal findings on screening mammograms. In 1,125 screening mammograms obtained in asymptomatic women referred by physicians, the findings in 63 (6%) were interpreted as requiring additional imaging or biopsy. Written reports were sent, and in all cases the office of the referring physician was notified directly by phone. Physicians were periodically contacted if no follow-up had been performed to resolve the questioned abnormality. In the first 2.5 months, no action had been taken in 40 of 63 (63%) of the recommendations. After additional calls, this diminished to 10 of 63 (16%) at 3.5 months, but at 4.5 months four of 63 (6%) patients had not undergone the recommended additional studies. These results suggest the need for development of systems to ensure prompt action in patients with abnormal findings at mammographic screening.

Why isn't every woman over 40 in a breast cancer detection program?

Mortality from breast cancer may be reduced by more than 10,000 deaths per year in this country if the recommendations for screening all asymptomatic women older than 40 years for breast cancer, issued in 1982 by the American Cancer Society and the American College of Radiology, are followed. Compliance with those recommendations six years later is poor, even in well-to-do, medically served populations, primarily because of poor compliance by physicians. Radiation risk is an often-cited concern, although it has been shown to be an insignificant factor in breast cancer screening. High cost, also cited as a concern, is less of a problem-the charges for mammography having declined steeply in the past few years. At the current price levels, it makes financial and humanitarian sense to provide screening rather than terminal care for metastatic breast cancer. The third concern cited by physicians, that of diagnostic accuracy, must be addressed by a careful and accurate statistical description of the results of each screening program. Sensitivity of more than 80% with positive predictive values of about a third can be achieved.

Factors relating to the sensory acuity of limbs with peripheral vascular insufficiency

We examined several possible causes for the high incidence of poor sensory acuity in the limbs of 176 patients with moderate to severe peripheral vascular insufficiency. We investigated the relationships of diabetes, alcoholism, and smoking, as well as the severity of peripheral vascular disease, to the integrity of basic sensory modalities such as two-point discrimination and perception of light touch. The presence or absence of diabetes exerted the strongest effect on peripheral sensation. In patients who did not have diabetes, sensation in the limbs was most strongly affected by whether the patient was an alcoholic. Smoking did not have a significant effect on limb sensation. Among nondiabetic, nonalcoholic patients, there was a weak residual effect related to the severity of the peripheral vascular insufficiency. Even among these patients, however, systemic factors predominated in determining the loss of sensation. We also examined the extent to which loss of sensation might be related to the development of ulcers. Among patients who were not diabetic, there was a highly significant relationship between loss of sensation and the presence of limb ulceration. Surprisingly, however, there was no discernable relationship between the presence of ulcers in diabetic patients and the degree of loss of peripheral sensation. This result suggests that a large percentage of ulcers seen in diabetic patients are not of neurogenic origin.

Water-soluble radiocontrast material in the treatment of postoperative ileus

Reviewed was a series of 47 obstetric, gynecologic, and general surgical patients with apparent postoperative ileus who had received an oral administration of water-soluble radiocontrast material. Forty of these patients were found to have an ileus, and seven to have a mechanical small bowel obstruction. In the 40 patients with ileus, prompt resolution of the ileus was obtained, no complications were noted, and the method provided rapid differentiation between ileus and obstruction. This modality of therapy offers an excellent alternative both therapeutically and diagnostically to the traditional treatment of ileus with intravenous fluid, nasogastric suction, and gastrointestinal rest.