Chemical affinity and dispersibility of boron nitride nanotubes.

Boron nitride nanotubes (BNNTs) are electrically insulating nanoparticles that display highly competitive elastic modulus and thermal conductivity. Long presented as potential fillers for nanocomposite applications, their poor dispersibility in most commodity polymers has, however, limited their spread. In this work, the chemical affinity of purified BNNTs, measured in terms of Hansen solubility parameters (HSP), were obtained through sedimentation tests in a wide set of organic solvents, taking into account relative sedimentation time. The parameters obtained were {δ d; δ p; δ h} = {16.8; 10.7; 14.7} ± {0.3; 0.9; 0.3} MPa1/2, with a Hildebrand parameter, δ t = 24.7 MPa1/2 and a sphere radius of 5.4 MPa1/2. The solubility parameters were determined considering complete dispersion of the purified nanomaterial, as well as the viscosity and density of the host solvent. These factors, combined with the high purity of the BNNTs, are crucial to minimize the uncertainty of the HSP characterization. Such refined values provide necessary insights both to optimize the solvent casting of unmodified BNNTs, and to orient the surface modification efforts that would be needed to integrate these nanomaterials into a wider range of host matrices.

Posttraumatic stress symptomatology after childhood traumatic brain injury.

The purpose of this study was to quantify and to identify predictors of posttraumatic stress disorder (PTSD) symptomatology after traumatic brain injury (TBI). Fifty children aged 6 to 14 years, hospitalized after TBI, were assessed soon after TBI regarding injury severity and preinjury psychiatric, socioeconomic, family functioning, and family psychiatric history status; neuroimaging was also analyzed. Psychiatric assessments were repeated 3, 6, 12, and 24 months after TBI. Only 2 of 46 (4%) subjects with at least one follow-up assessment developed PTSD. However, the frequency with which subjects experienced at least one PTSD symptom ranged from 68% in the first 3 months to 12% at 2 years in assessed children. The presence of an internalizing disorder at time of injury followed by greater injury severity were the most consistent predictors of PTSD symptomatology. It is apparent, therefore, that PTSD and subsyndromal posttraumatic stress disturbances occur despite neurogenic amnesia. These problems should be treated, particularly if symptoms persist beyond 3 months.

Traumatic brain injury in children and adolescents: psychiatric disorders at one year.

Factors predictive of psychiatric outcome in the second 6 months following traumatic brain injury (TBI) in 43 children and adolescents were assessed prospectively. The outcome measure was the presence of a psychiatric disorder not present before the injury ("novel"). Out of six models tested, four were predictive of novel psychiatric disorder: preinjury family function, family psychiatric history, socioeconomic class/intellectual function, and behavior/adaptive function. Post hoc analyses suggested that preinjury family functioning measured by a structured interview was a significant predictive variable. Severity of injury, when reclassified as severe versus mild/moderate TBI, significantly predicted novel psychiatric disorders. These data suggest that some children, identifiable through clinical assessment, are at increased risk for psychiatric disorders following TBI.

Attention-deficit hyperactivity symptomatology after traumatic brain injury: a prospective study.

OBJECTIVE: To study prospectively the course of attention-deficit hyperactivity (ADH) symptomatology in children and adolescents after traumatic brain injury (TBI). It was hypothesized that ADH symptomatology would be significantly related to severity of injury. METHOD: Subjects were children (n = 50) aged 6 to 14 years at the time they were hospitalized after TBI. The study used a prospective follow-up design. Assessments of preinjury psychiatric, behavioral, socioeconomic, family functioning, and family psychiatric history status were conducted. Severity of injury was assessed by standard clinical scales, and neuroimaging was analyzed. RESULTS: The main finding of this study was that change in ADH symptomatology in the first 2 years after TBI in children and adolescents was significantly related to severity of injury. Overall ADH symptomatology during the study was significantly related to a measure of family dysfunction when family psychiatric history, socioeconomic status, and severity of injury were controlled. CONCLUSION: The presence of a positive "dose-response" relationship between severity of injury and change in ADH symptoms, present from the 3-month assessment, was consistent with an effect directly related to brain damage.

Oppositional defiant disorder symptomatology after traumatic brain injury: a prospective study.

Our goal was to prospectively study the course of oppositional defiant disorder (ODD) symptomatology in children and adolescents in the first 2 years after traumatic brain injury (TBI). Fifty children aged 6 to 14, hospitalized after TBI, were assessed soon after TBI regarding injury severity; preinjury psychiatric, socioeconomic, family functioning, and family psychiatric history status; and neuroimaging was analyzed. ODD symptomatology in the first year after TBI was related to preinjury family function, social class, and preinjury ODD symptomatology. Increased severity of TBI predicted ODD symptomatology 2 years after injury. Change (from before TBI) in ODD symptomatology at 6, 12, and 24 months after TBI was influenced by socioeconomic status. Only at 2 years after injury was severity of injury a predictor of change in ODD symptomatology. The influence of psychosocial factors appears greater than severity of injury in accounting for ODD symptomatology and change in such symptomatology in the first but not the second year after TBI in children and adolescents. This appears related to persistence of new ODD symptomatology after more serious TBI.

The Neuropsychiatric Rating Schedule: reliability and validity.

OBJECTIVE: To evaluate reliability and validity for the Neuropsychiatric Rating Schedule (NPRS) interview designed to permit diagnosis of organic personality syndrome (OPS) or personality change due to a general medical condition (PC). METHOD: Subjects from prospective (n = 50) and retrospective (n = 72) studies of traumatic brain injury were aged 6 through 18 years. Parents and children were informants for the NPRS. Convergent and discriminant validity of subtypes of OPS/PC were assessed against standard scales completed by parents and teachers. Interrater reliability data (n = 20), test-retest reliability data (n = 42), as well as sensitivity-to-change data (n = 37) were collected. RESULTS: All subtypes of OPS/PC were diagnosed, but apathy and paranoia subtypes were rare. Rating scale data supported convergent validity of OPS/PC subtypes generated with the NPRS. Affective instability, rage/aggression, and inappropriate social judgment were moderately to highly correlated, but apathy and paranoia could be discriminated from each of these subtypes. Interrater agreement for NPRS items was fair to excellent for all but one item (paranoia). Test-retest reliability was fair to good, and sensitivity to change was demonstrated. CONCLUSION: The NPRS generated reliable and valid diagnoses of the common subtypes of OPS/PC.

Predictors of family functioning after traumatic brain injury in children and adolescents.

OBJECTIVE: To assess factors predictive of family outcome in the first 2 years after traumatic brain injury (TBI) in children and adolescents. METHOD: Subjects were children aged 6 to 14 at the time they were hospitalized after TBI. The study used a prospective follow-up design. Assessments of preinjury factors (psychiatric family functioning, and family life events), injury factors (severity of injury), and postinjury factors (coping and development of a psychiatric disorder, never before present, i.e., "novel") were conducted using standard clinical scales. The outcome measure was family function as assessed with standardized family functioning interviews (at 12 and 24 months after TBI) and primary caretaker self-report questionnaires (at 3 and 6 months after TBI). RESULTS: Fifty subjects enrolled, and the analyses focused on 37, 41, 43, and 42 subjects assessed at the 3-, 6-, 12-, and 24-month follow-up evaluations, respectively. The strongest influences on family functioning after childhood TBI are preinjury family functioning, the development of a "novel" psychiatric disorder in the child, and preinjury family life events or stressors. CONCLUSIONS: These data suggest that there are families, identifiable through clinical assessment, at increased risk for family dysfunction after a child's TBI. Early identification and treatment of the child's psychopathology and family dysfunction may attenuate the associated morbidity.

Traumatic brain injury in children and adolescents: psychiatric disorders at two years.

OBJECTIVE: To extend findings regarding predictive factors of psychiatric outcome from the first to the second year after traumatic brain injury (TBI) in children and adolescents. METHOD: Subjects were children aged 6 to 14 years at the time they were hospitalized after TBI. The study used a prospective follow-up design. Assessments of preinjury psychiatric, behavioral, adaptive functioning, family functioning and family psychiatric history status were conducted. Severity of injury was assessed by standard clinical scales and neuroimaging was analyzed. The outcome measure was the presence of a psychiatric disorder, not present before the injury ("novel"), during the second year after TBI. RESULTS: Fifty subjects enrolled, and the analyses focused on 42 subjects followed at 24 months. Severity of injury, preinjury family function, and preinjury lifetime psychiatric history predicted the development of a "novel" psychiatric disorder present in the second year. CONCLUSION: These data suggest that there are children, identifiable through clinical assessment, at increased risk for "novel" psychiatric disorders in the second year after TBI.

Generalized anxiety and depression. Assessment over 2 years after stroke.

The authors examined the course of anxiety up to 2 years after stroke in relation to depressive symptoms, impairment in activities of daily living (ADLs), and social functioning. One hundred forty-two patients were evaluated at 3, 6, 12, and 24 months after stroke. Anxiety was associated with greater depression severity at all follow-up visits. Depression severity was associated with impairment in ADLs at followup; association of anxiety and impairment in ADLs was present only at the intake visit, with independent effects only for women. Women reported more symptoms of both anxiety and depression during the 2-year period. Younger patients reported more anxiety symptoms, but there was no difference between age-groups in depressive symptoms. Severity of anxiety was also related to higher depression scores at initial hospitalization, but not in the remainder of the 2-year period. In summary, anxiety is associated with increased severity of depressive symptoms and greater impairment in function primarily during the acute hospitalization period. Women and younger patients also may be more vulnerable to anxiety after stroke.

Traumatic brain injury in children and adolescents: psychiatric disorders in the second three months.

Psychiatric disorders may be common after traumatic brain injury (TBI) in children, yet there is a death of prospective studies examining this problem. Fifty children aged 6 to 14, hospitalized after TBI, were assessed soon after TBI regarding preinjury psychiatric, behavioral, adaptive, and family functioning, family psychiatric history status and injury severity. The outcome measure was the presence of a "novel" psychiatric disorder (not present before the injury) during the second 3 months after the injury. Forty-two subjects were reassessed at 6 months. Severity of injury, family psychiatric history, and family function predicted a novel psychiatric disorder. Among children suffering a mild/moderate injury, those with preinjury lifetime psychiatric disorders were no longer (as they had been in the first 3 months) at higher risk than those without such a lifetime history. Thus, there appeared to be children, identifiable through clinical assessment, at increased risk for novel psychiatric disorders after TBI.

Traumatic brain injury in children and adolescents: psychiatric disorders in the first three months.

OBJECTIVE: To assess predictive factors of psychiatric outcome in the first 3 months after traumatic brain injury (TBI) in children and adolescents. METHOD: Subjects were children aged 6 to 14 years at the time they were hospitalized after TBI. The study used a prospective follow-up design. Assessments of preinjury psychiatric, behavioral, adaptive functioning, family functioning, and family psychiatric history status were conducted. Severity of injury was assessed by standard clinical scales and neuroimaging was analyzed. The outcome measure was the development of a psychiatric disorder, never before present ("novel") in a subject during the first 3 months after the TBI. RESULTS: Fifty subjects enrolled, and the analyses focused on 37 subjects followed up at 3 months. Increasing severity of injury, presence of a lifetime psychiatric disorder, family psychiatric history, family dysfunction, and lower socioeconomic class/preinjury intellectual function predicted the development of a "novel" psychiatric disorder in the first 3 months of follow-up. CONCLUSIONS: These data suggest that there are children, identifiable through clinical assessment, at increased risk for development of psychiatric disorders in the first 3 months after TBI.

Clinical correlates of early-onset and late-onset poststroke generalized anxiety.

OBJECTIVE: The authors' goal was to determine if generalized anxiety diagnosed while a patient was hospitalized for stroke (early onset) had the same clinical correlates as anxiety beginning 3 months or more after the stroke (late onset). METHOD: Patients with acute stroke (N = 142) were examined while they were in the hospital and 3, 6, 12, and 24 months later for the presence of anxiety symptoms. Patients underwent a structured psychiatric interview as well as assessment of cognitive, physical, and social function at each visit. Patients with early-onset and late-onset poststroke generalized anxiety were identified and compared to patients without poststroke generalized anxiety. RESULTS: The frequency of early-onset poststroke generalized anxiety was 27% and that of late-onset poststroke generalized anxiety was 23%. Three-quarters of the anxious patients had comorbid major or minor depression. Patients who developed early-onset or late-onset poststroke generalized anxiety were no more socially, cognitively, or physically impaired than patients who did not develop anxiety. Early-onset but not late-onset anxiety was associated with a previous history of psychiatric disorder. The median duration of late-onset anxiety was 3.0 months, and that of early-onset anxiety was 1.5 months. The presence of anxiety was significantly associated with depression; onset of depression and onset of anxiety occurred at approximately the same time. CONCLUSIONS: These findings suggest that although early-onset and late-onset poststroke generalized anxiety are phenomenologically similar, they may be the result of different pathophysiological mechanisms.

Generalized anxiety disorder after stroke.

A series of 309 admissions to a stroke unit was examined for anxiety symptoms. Patients were diagnosed with DSM-III-R generalized anxiety disorder (GAD) symptom criteria. They were divided into groups of no anxiety (59.2%), worried but not fulfilling GAD criteria (13.9%), and GAD (26.9%). Patients were then divided into depressed and nondepressed groups based on the existence of DSM-III major or minor (dysthymic) depression. These groups were not significantly different in their background characteristics, family or personal psychiatric history, social support or the severity of physical impairment. Anxiety plus depression was associated with left cortical lesions, whereas anxiety alone was associated with right hemisphere lesions. Patients with worry had anterior and patients with GAD had posterior right hemisphere lesions. These findings suggest that anxiety disorder (independent of depression) is not related to background characteristics or to severity of impairment but is, in part, influenced by the brain structures that are injured.