Differential larval responses of two ecologically similar insects (Odonata) to temperature and resource variation.

How species respond to shifting environmental conditions is a central question in ecology, especially because ecosystems are experiencing rapidly changing climatic conditions. However, predicting the responses of species interactions and community composition to changing conditions is often difficult. We examined the effects of rearing temperature and resource level on larval survival of two ecologically similar dragonflies, Erythemis collocata and Pachydiplax longipennis. Within high and low (26 and 21°C) temperatures, we crossed species and resource level and reared larvae individually. We predicted that warmer temperatures would reduce survival and increase growth rate, that higher resource availability would increase survival and growth rate, and that the two species would respond similarly. We found that increased temperature reduced survival for both species. There was also an interaction between temperature and species: E. collocata had higher survival at the lower temperature, but lower survival at the higher temperature when compared to P. longipennis. Resource level did not affect survival. In general, P. longipennis grew more than E. collocata, with no effects of temperature or resource level. These results suggest that these species respond dissimilarly to changing thermal conditions, that increased food availability cannot always compensate for the negative effects of higher temperatures, and that climate change may affect interactions between these two sympatric, ecologically similar species, with potential consequences for community composition.

Atypical femoral fractures and bisphosphonate treatment: experience in two large United Kingdom teaching hospitals.

We performed a retrospective review of all patients admitted to two large University Hospitals in the United Kingdom over a 24-month period from January 2008 to January 2010 to identify the incidence of atypical subtrochanteric and femoral shaft fractures and their relationship to bisphosphonate treatment. Of the 3515 patients with a fracture of the proximal femur, 156 fractures were in the subtrochanteric region. There were 251 femoral shaft fractures. The atypical fracture pattern was seen in 27 patients (7%) with 29 femoral shaft or subtrochanteric fractures. A total of 22 patients with 24 atypical fractures were receiving bisphosphonate treatment at the time of fracture. Prodromal pain was present in nine patients (11 fractures); 11 (50%) of the patients on bisphosphonates suffered 12 spontaneous fractures, and healing of these fractures was delayed in a number of patients. This large dual-centre review has established the incidence of atypical femoral fractures at 7% of the study population, 81% of whom had been on bisphosphonate treatment for a mean of 4.6 years (0.04 to 12.1). This study does not advocate any change in the use of bisphosphonates to prevent fragility fractures but attempts to raise awareness of this possible problem so symptomatic patients will be appropriately investigated. However, more work is required to identify the true extent of this new and possibly increasing problem.

Voxel-based analysis of diffusion tensor imaging in mild traumatic brain injury in adolescents.

BACKGROUND AND PURPOSE: DTI of normal-appearing WM as evaluated by conventional MR imaging in mTBI has the potential to identify important regional abnormalities that relate to PCS. VBA was used to examine WM changes in acute mTBI. MATERIALS AND METHODS: WM was assessed between 1 and 6 days postinjury with voxel-based DTI analyses in 10 adolescent patients with mTBI and 10 age-matched control participants. In addition to the voxel-based group, analysis used to identify brain pathology across all patients with mTBI, 2 voxel-based linear regressions were performed. These analyses investigated the relation between 1) the ADC and PCS severity scores, and 2) ADC and scores on the BSI of emotional symptoms associated with mTBI. We hypothesized that frontotemporal WM changes would relate to symptoms associated with PCS and endorsed on the BSI. RESULTS: Patients with mTBI demonstrated significant reductions in ADC in several WM regions and in the left thalamus. As expected, no increases in ADC were found in any region of interest. All injury-affected regions showed decreased radial diffusivity, unchanged AD, and increased FA, which is consistent with axonal cytotoxic edema, reflective of acute injury. CONCLUSIONS: Whole-brain WM DTI measures can detect abnormalities in acute mTBI associated with PCS symptoms in adolescents.

Diffusion tensor imaging of acute mild traumatic brain injury in adolescents.

BACKGROUND: Despite normal CT imaging and neurologic functioning, many individuals report postconcussion symptoms following mild traumatic brain injury (MTBI). This dissociation has been enigmatic for clinicians and investigators. METHODS: Diffusion tensor imaging tractography of the corpus callosum was performed in 10 adolescents (14 to 19 years of age) with MTBI 1 to 6 days postinjury with Glasgow Coma Scale score of 15 and negative CT, and 10 age- and gender-equivalent uninjured controls. Subjects were administered the Rivermead Post Concussion Symptoms Questionnaire and the Brief Symptom Inventory to assess self-reported cognitive, affective, and somatic symptoms. RESULTS: The MTBI group demonstrated increased fractional anisotropy and decreased apparent diffusion coefficient and radial diffusivity, and more intense postconcussion symptoms and emotional distress compared to the control group. Increased fractional anisotropy and decreased radial diffusivity were correlated with severity of postconcussion symptoms in the MTBI group, but not in the control group. CONCLUSIONS: In adolescents with mild traumatic brain injury (MTBI) with Glasgow Coma Scale score of 15 and negative CT, diffusion tensor imaging (DTI) performed within 6 days postinjury showed increased fractional anisotropy and decreased diffusivity suggestive of cytotoxic edema. Advanced MRI-based DTI methods may enhance our understanding of the neuropathology of TBI, including MTBI. Additionally, DTI may prove more sensitive than conventional imaging methods in detecting subtle, but clinically meaningful, changes following MTBI and may be critical in refining MTBI diagnosis, prognosis, and management.

Nitric oxide: a major determinant of mast cell phenotype and function.

Mast cells (MC) are important in the numerous physiological processes of homeostasis and disease. Most notably, MC are critical effectors in the development and exacerbation of allergic disorders. Nitric oxide (NO) is a diatomic radical produced by nitric oxide synthase (NOS), and has pluripotent cell signaling and cytotoxic properties. NO can influence many MC functions. Recent evidence shows the source of this NO can be from the mast cell itself. Governing the production of this endogenous NO, through alterations in the expression of tetrahydrobiopterin (BH4), a NOS cofactor, has stabilizing effects on MC degranulation. Furthermore, NO regulates the synthesis and secretion of de novo generated mediators, including leukotrienes and chemokines. These novel observations add to the growing body of knowledge surrounding the role of NO in the MC.

[The neurobehavioral rating scale-revised: assessment of concurrent validity]. / Echelle neurocomportementale révisée: étude de la validité concourante.

UNLABELLED: Cognitive and behavioral impairment are a major source of disability in daily living of patients with traumatic brain injury (TBI). The Neurobehavioral Rating Scale-Revised (NRS-R) is a short, easy-to administer interview tool developed to improve assessment by clinicians. Data are available on its criterion validity and reliability, but the concurrent validity of the French NRS-R was not yet documented. OBJECTIVE: To assess the concurrent validity of the NRS-R with current psychometric tests. METHOD: One hundred and four patients with TBI enrolled in a community adjustment program underwent concurrent examination with the NRS-R, cognitive tests assessing memory, attention, and executive functions, and scales of anxiety (STAI) and depressive mood (CES-D). Intercorrelations were undertaken between these variables and the five factors of the NRS-R: F1, intentional behavior; F2, lowered emotional state; F3, survival-oriented behaviour/hightened emotional state; F4, arousal state; and F5, language. Patients were 82 men and 22 women, the mean age was 28.5 years, and 70% had severe TBI (Glasgow coma score [GCS] below 8 on admission). They were assessed 52 months on average after their injury. RESULTS: Factor F1 was correlated with results on the GCS (P<0.05), the Tower of London test (TL, P<0.01), the Trail Making Test (TMT, P<0.01), divided attention (DA) and inhibition (IN) subscales of the Zimmermann and Fimm's Attention battery (TEA) (P<0.01) and reverse digit span (DS, P<0.05). Factor F2 was positively related to age at injury, time since injury (TSI) (P<0.05) and CESD and STAI scores (P<0.001). Factor F3 was related to DA (P<0.01) TL scores and TSI (P<0.05). Factor F4 was related to TL, TMT, DA, flexibility, DS (P<0.05), TSI, duration of post-traumatic amnesia, CES-D score (P<0.05) and STAI scores (P<0.01). Factor F5 was related to GCS, DA (P<0.05), and reaction time on the subscales IN and Go/nogo (GO) of the TEA battery (P<0.01). The NRS-R total score was related to CESD, STAI scores, TMT score, DA (P<0.01) and TL score, IN and GO scores and TSI (P<0.05). DISCUSSION: As McCauley et al found with the English version of the NRS-R, significant relationships were found between NRS-R factor scores, cognitive tests and emotional scales. Relationships were also found between factor scores and indicators of injury severity and time since injury. These data suggest fair concurrent validity of the NRS-R.

Nitric oxide: a major determinant of mast cell phenotype and function

Mast cells (MC) are important in the numerous physiological processes of homeostasis and disease. Most notably, MC are critical effectors in the development and exacerbation of allergic disorders. Nitric oxide (NO) is a diatomic radical produced by nitric oxide synthase (NOS), and has pluripotent cell signaling and cytotoxic properties. NO can influence many MC functions. Recent evidence shows the source of this NO can be from the mast cell itself. Governing the production of this endogenous NO, through alterations in the expression of tetrahydrobiopterin (BH4), a NOS cofactor, has stabilizing effects on MC degranulation. Furthermore, NO regulates the synthesis and secretion of de novo generated mediators, including leukotrienes and chemokines. These novel observations add to the growing body of knowledge surrounding the role of NO in the MC.

The neurobehavioural rating scale-revised: sensitivity and validity in closed head injury assessment.

OBJECTIVES: To investigate the factor structure and psychometric properties of the neurobehavioural rating scale-revised (NRS-R) and to determine its usefulness in clinical trials. METHODS: A consecutive series of patients sustaining severe closed head injury were evacuated to one of 11 large regional North American trauma centres and entered into a randomised, phase III, multicentre clinical trial investigating the therapeutic use of moderate hypothermia. Acute care personnel were blinded to outcome and outcome personnel were blinded to treatment condition. The Glasgow outcome scale (GOS) was the primary outcome measure. Secondary outcome measures included the disability rating scale (DRS) and the NRS-R. RESULTS: Exploratory factor analysis of NRS-R data collected at 6 months after injury (n=210) resulted in a five factor model including: (1) executive/cognition, (2) positive symptoms, (3) negative symptoms, (4) mood/affect, and (5) oral/motor. These factors showed acceptable internal consistency (0.62 to 0.88), low to moderate interfactor correlations (0.19 to 0.61), and discriminated well between GOS defined groups. Factor validity was demonstrated by significant correlations with specific neuropsychological domains. Significant change was measured from 3 to 6 months after injury for the total score (sum of all 29 item ratings) and all factor scores except mood/affect and positive symptoms. The total score and all factor scores correlated significantly with concurrent GOS and DRS scores. CONCLUSIONS: The NRS-R is well suited as a secondary outcome measure for clinical trials as its completion rate exceeds that of neuropsychological assessment and it provides important neurobehavioural information complementary to that provided by global outcome and neuropsychological measures.

Validity and sensitivity to change of the extended Glasgow Outcome Scale in mild to moderate traumatic brain injury.

Using a structured outcome interview, this study addressed the validity and sensitivity to change of the Glasgow Outcome Scale (GOS) and the Extended GOS (GOSE) in a prospective study of patients who sustained mild (n = 30) to moderate (n = 13) traumatic brain injury (TBI) or general trauma (n = 44). The patients were recruited from the emergency center or inpatient units of Ben Taub General Hospital and invited to participate in follow-up examinations at 3 and 6 months. Using a series of functional outcome measures, assessment of affective status, and neuropsychological tests as criteria, the validity of the GOSE generally exceeded the GOS. Analysis of the outcome data for the patients who completed both the 3-month and 6-month assessments disclosed that the GOSE was more sensitive to change than the GOS. Comparison of the 3-month outcome data disclosed that the GOSE and GOS scores did not differ for the TBI and general trauma groups. These findings lend further support for utilization of the GOSE in clinical trials when it is based on a structured interview.

Use of the Disability Rating Scale Recovery curve as a predictor of psychosocial outcome following closed-head injury.

Rapid rate of recovery has been associated with better outcome following closed-head injuries, but few studies have compellingly demonstrated this. This study used growth curve analyses of Disability Rating Scale (DRS) scores at acute hospitalization discharge, 1, 3, and 6 months post injury in a sample of 55 patients with a closed-head injury. Six month post-injury outcome measures were taken from significant other (SO) responses on the NYU Head Injury Family Interview (NYU-HIFI) including severity and burden ratings of affective/neurobehavioral disturbance, cognitive deficits, and physical/dependency status. Rate of recovery (linear and curvilinear recovery curve components) was significantly related to the level of affective/neurobehavioral severity, and the severity and burden of SO-perceived cognitive deficits. Only the intercept of the DRS recovery curve was associated with the SO-perceived severity and burden of physical/dependency status. Growth curve modeling is a meaningful and powerful tool in predicting head injury outcome.

Large carbon isotope fractionation associated with oxidation of methyl halides by methylotrophic bacteria.

The largest biological fractionations of stable carbon isotopes observed in nature occur during production of methane by methanogenic archaea. These fractionations result in substantial (as much as approximately 70 per thousand) shifts in delta(13)C relative to the initial substrate. We now report that a stable carbon isotopic fractionation of comparable magnitude (up to 70 per thousand) occurs during oxidation of methyl halides by methylotrophic bacteria. We have demonstrated biological fractionation with whole cells of three methylotrophs (strain IMB-1, strain CC495, and strain MB2) and, to a lesser extent, with the purified cobalamin-dependent methyltransferase enzyme obtained from strain CC495. Thus, the genetic similarities recently reported between methylotrophs, and methanogens with respect to their pathways for C(1)-unit metabolism are also reflected in the carbon isotopic fractionations achieved by these organisms. We found that only part of the observed fractionation of carbon isotopes could be accounted for by the activity of the corrinoid methyltransferase enzyme, suggesting fractionation by enzymes further along the degradation pathway. These observations are of potential biogeochemical significance in the application of stable carbon isotope ratios to constrain the tropospheric budgets for the ozone-depleting halocarbons, methyl bromide and methyl chloride.

Factor analysis of an outcome interview for use in clinical trials of traumatically brain-injured patients: a preliminary study.

OBJECTIVE: To study the factor structure, internal consistency, concurrent validity, and sensitivity to detect change in patient report of problems of a structured interview in relationship with accepted outcome measures. DESIGN: Outcome status of patients with severe traumatic brain injury participating in a randomized, phase III, multicenter clinical trial was assessed at 6 mo postinjury using the Glasgow Outcome Scale, the Disability Rating Scale, and the Severe Traumatic Brain Injury Outcome Interview. RESULTS: Exploratory factor analysis of the Severe Traumatic Brain Injury Outcome Interview produced a meaningful five-factor model: (1) activities of daily living; (2) cognitive; (3) affective; (4) behavioral; and (5) instrumental activities of daily living. The internal consistency of the factors ranged from moderate (0.61 instrumental activities of daily living) to high (0.94 activities of daily living); the interfactor correlations were moderate. The summed factor scores were significantly correlated with measures of global outcome: the Glasgow Outcome Scale (r = 0.66; P < 0.0001) and the Disability Rating Scale (r = 0.61; P < 0.0001). Patient report of cognitive problems correlated moderately with the neuropsychological tests. The summed factor scores were sensitive to change over time. CONCLUSIONS: Overall, the interview assessed the major important features of outcome pertinent to traumatic brain injury and demonstrated greater sensitivity to subtle changes over time than the unidimensional approaches, such as the Glasgow Outcome Scale and Disability Rating Scale.

Continuous flow stable isotope methods for study of delta(13)C fractionation during halomethane production and degradation.

Gas chromatography/mass spectrometry/isotope ratio mass spectrometry (GC/MS/IRMS) methods for delta(13)C measurement of the halomethanes CH(3)Cl, CH(3)Br, CH(3)I and methanethiol (CH(3)SH) during studies of their biological production, biological degradation, and abiotic reactions are presented. Optimisation of gas chromatographic parameters allowed the identification and quantification of CO(2), O(2), CH(3)Cl, CH(3)Br, CH(3)I and CH(3)SH from a single sample, and also the concurrent measurement of delta(13)C for each of the halomethanes and methanethiol. Precision of delta(13)C measurements for halomethane standards decreased (+/-0.3, +/-0.5 and +/-1.3 per thousand) with increasing mass (CH(3)Cl, CH(3)Br, CH(3)I, respectively). Given that carbon isotope effects during biological production, biological degradation and some chemical (abiotic) reactions can be as much as 100 per thousand, stable isotope analysis offers a precise method to study the global sources and sinks of these halogenated compounds that are of considerable importance to our understanding of stratospheric ozone destruction.

Lack of effect of induction of hypothermia after acute brain injury.

BACKGROUND: Induction of hypothermia in patients with brain injury was shown to improve outcomes in small clinical studies, but the results were not definitive. To study this issue, we conducted a multicenter trial comparing the effects of hypothermia with those of normothermia in patients with acute brain injury. METHODS: The study subjects were 392 patients 16 to 65 years of age with coma after sustaining closed head injuries who were randomly assigned to be treated with hypothermia (body temperature, 33 degrees C), which was initiated within 6 hours after injury and maintained for 48 hours by means of surface cooling, or normothermia. All patients otherwise received standard treatment. The primary outcome measure was functional status six months after the injury. RESULTS: The mean age of the patients and the type and severity of injury in the two treatment groups were similar. The mean (+/-SD) time from injury to randomization was 4.3+/-1.1 hours in the hypothermia group and 4.1+/-1.2 hours in the normothermia group, and the mean time from injury to the achievement of the target temperature of 33 degrees C in the hypothermia group was 8.4+/-3.0 hours. The outcome was poor (defined as severe disability, a vegetative state, or death) in 57 percent of the patients in both groups. Mortality was 28 percent in the hypothermia group and 27 percent in the normothermia group (P=0.79). The patients in the hypothermia group had more hospital days with complications than the patients in the normothermia group. Fewer patients in the hypothermia group had high intracranial pressure than in the normothermia group. CONCLUSIONS: Treatment with hypothermia, with the body temperature reaching 33 degrees C within eight hours after injury, is not effective in improving outcomes in patients with severe brain injury.

Depression and posttraumatic stress disorder at three months after mild to moderate traumatic brain injury.

To investigate the frequency and risk factors of major depressive disorder (MDD) after mild to moderate traumatic brain injury (TBI), 69 TBI and 52 general trauma (GT) patients were prospectively recruited and studied at 3-months postinjury. There was a nonsignificant difference in the proportion of MDD patients in the TBI and GT groups. Therefore, a composite MDD group (TBI and GT patients) was compared to patients who were nondepressed. Female gender was related to MDD, but no other risk factors were identified. MDD was associated with disability (Glasgow Outcome Scale, Community Integration Questionnaire) and cognitive impairment. MDD was comorbid with posttraumatic stress disorder. Implications for postacute management of mild to moderate TBI are discussed.

Postconcussional disorder following mild to moderate traumatic brain injury: anxiety, depression, and social support as risk factors and comorbidities.

Previous studies of postconcussional disorder (PCD) have utilized a dimensional approach (i.e., number and/or severity ratings of symptoms) to study postconcussional symptoms. This study used a syndromal approach (modified form of the DSM-IV criteria) for investigating risk factors for developing PCD, 3-months postinjury. The head trauma requirement was waived in order to determine specificity of symptoms to traumatic brain injury. Preliminary results from this ongoing study indicated significant risk factors including female gender, poor social support, and elevated self-reported depressive symptoms at 1-month postinjury. Comorbidities included concurrent diagnosis of major depressive disorder and/or posttraumatic stress disorder. Hispanics were significantly less likely to develop PCD than other racial/ethnic groups. PCD resulted more frequently from motor vehicle accidents and assaults. Screening tests for PCD risk factors/comorbidities performed shortly after injury (i.e., during routine follow-up clinic appointments) coupled with appropriate referrals for psychoeducational interventions and support groups may avoid prolonged loss of productivity and poor perceived quality of life in these patients.

An isotopic approach for understanding the CH(3)Br budget of the atmosphere.

The atmospheric budget of methyl bromide (CH(3)Br), an ozone-depleting gas, is highly uncertain, because it has complex sources and sinks. Although oceans, biomass burning, and industrial production are identified as the major sources, the fraction of CH(3)Br that is contributed by each source is not well known. A mass-balance approach that exploits differences in the carbon isotopic signature (delta(13)C) of CH(3)Br sources and sinks may provide a means of reducing uncertainties in the atmospheric budget. This approach depends on the distinctiveness of industrially produced methyl bromide. Our delta(13)C measurements of industrial CH(3)Br from the three largest manufacturers worldwide yield a weighted average of -54.4 per thousand relative to the Peedee Belemnite standard. This result suggests that industrial CH(3)Br is isotopically distinct and that the carbon isotopic composition of atmospheric CH(3)Br may indicate what fraction of atmospheric CH(3)Br is anthropogenic.

Response to dietary dilution in an omnivorous freshwater turtle: implications for ontogenetic dietary shifts.

Several species of freshwater turtles in the family Emydidae undergo an ontogenetic dietary shift; as juvenile turtles mature, they change from a primarily carnivorous to a primarily herbivorous diet. It has been hypothesized that this shift results from an unfavorable ratio of gut capacity to metabolic rate that prevents small reptiles from processing adequate volumes of plant material to meet their energetic demands. Effects of dietary dilution on intake were evaluated in two size classes of red-eared sliders (Trachemys scripta elegans) to test whether small reptiles have a lower capacity to compensate for low-quality diets through increased intake than do larger conspecifics. Artificial diets with an inert diluent were offered to two size classes of turtles, and mass-specific intakes of dry matter, energy, and nitrogen were calculated. Both small (28.7+/-4.9 g body mass, mean mass+/-SD) and large (1,230+/-94 g body mass) turtles compensated for dietary dilution and maintained constant energy and nitrogen intakes on diets with lower energy content than common aquatic plants. Thus, body size did not affect the ability to respond to nutritional dilution, which suggests that processing limitations imposed by small body size do not constrain juveniles from adopting an herbivorous diet.

Regional brain tissue composition in children with hydrocephalus. Relationships with cognitive development.

OBJECTIVE: To determine whether children with shunted hydrocephalus show variations in regional brain tissue composition that relate to cognitive functions. DESIGN: Nonequivalent control group. PATIENTS AND METHODS: Magnetic resonance imaging (MRI) and cognitive skills assessments were obtained on 28 children, 6 to 9 years of age, with shunted hydrocephalus and 13 normal control subjects comparable in age, gender, ethnicity, and socioeconomic status. Three consecutive MRI slices below the vertex were segmented using a fuzzy clustering algorithm to separate pixels into gray matter, white matter, and cerebrospinal fluid (CSF) in quadrants representing left and right anterior and posterior brain regions. The cognitive skills assessments included the Wechsler Intelligence Scale for Children-Revised verbal and performance IQ scores, neuropsychological composites of language and visuospatial skills, a measure of visuomotor dexterity, and 2 measures of problem-solving abilities. The MRI data were analyzed in a group x tissue x hemisphere x region analysis of variance. Spearman rho correlations were computed within the hydrocephalus group between the MRI and cognitive measures. RESULTS: Children with hydrocephalus showed reductions in overall gray matter percentages and corresponding increased CSF percentages that were more pronounced in posterior than anterior regions of both hemispheres. White matter percentages were reduced in children with hydrocephalus only in the left posterior quadrant. Correlations of posterior, but not anterior, CSF and gray matter percentages were significant with verbal and performance IQ scores and language, visuospatial, and visuomotor dexterity skills, but not with problem-solving abilities. Children with hydrocephalus who had proportionately greater posterior than anterior CSF percentages had significantly poorer visuomotor dexterity and visuospatial skills than did hydrocephalic children with proportionate CSF percentages. CONCLUSION: Regional variations in brain tissue composition in children with shunted hydrocephalus correlate with a variety of cognitive and visuomotor functions.