Neurite orientation dispersion and density imaging quantifies corticospinal tract microstructural organization in children with unilateral cerebral palsy

Children with unilateral cerebral palsy (UCP) due to early brain injury exhibit disrupted connectivity of corticospinal tracts (CSTs), which can be quantified using diffusion‐weighted magnetic resonance imaging (DWI). Diffusion tensor imaging (DTI) is commonly used to quantify white matter organization, however, this model lacks the biological specificity to accurately describe underlying microstructural properties. Newer approaches, such as neurite orientation dispersion and density imaging (NODDI), may provide more biologically accurate information regarding CST microstructure. In this study, we directly compared metrics of CST microstructure using NODDI and DTI models to characterize the microstructural organization of corticospinal pathways. Twenty participants with UCP participating in a neuromodulation/rehabilitation intervention underwent imaging including multi‐shell DWI; 10 participants' datasets were adequately completed for neuroimaging analysis. Task fMRI‐guided probabilistic tractography from motor cortex to brainstem was performed at baseline and follow‐up to reconstruct the CSTs. Diffusion metrics were compared between hemispheres at baseline, and between baseline and follow‐up to test for intervention effects. Correlation analyses were used to compare baseline metrics to changes in hand function following the intervention. DTI results showed that mean fractional anisotropy in lesioned and nonlesioned CSTs did not significantly differ, but mean, axial, and radial diffusivity were greater in the lesioned CST. For NODDI, intracellular volume fraction (ICVF) and orientation dispersion index (ODI) were lower in the lesioned CST. Unimanual function was strongly correlated with ICVF, but not FA. NODDI may reveal distinct properties of CST microstructure that are linked to motor function, indicating their potential in characterizing brain structure and development.     

Iatrogenic pulmonary overpressure accident

An unconscious victim of an overdose was intubated with an endotracheal tube to prevent aspiration. The respiratory therapist deflated the cuff of the endotracheal tube to allow for a retrograde oral air leak and then tightly attached the oxygen tube directly to the endotracheal tube. Seconds later there was a loud pop as the oxygen tube blew off the end of the endotracheal tube. The patient sustained both a hemodynamic and a neurologic decompensation as the result of marked pulmonary overinflation, with bilateral pneumothoraces and probable cerebral and coronary artery air emboli. We present the case in the hope that it will help avoid any such future occurrences.     

Percutaneous coronary intervention in a patient with immune thrombocytopenia purpura.

The appropriate regimen of platelet inhibitors that should be used in patients with immune thrombocytopenia purpura (ITP; formerly called idiopathic thrombocytopenic purpura) who are undergoing percutaneous coronary intervention is unclear. We report the case of a patient with ITP who underwent two separate coronary interventions. The first involved the use of aspirin and a cutting balloon to treat obstructive disease of the left circumflex. When the patient presented with restenosis, he received eptifibatide, clopidogrel, and an intracoronary stent. He is currently 16 months removed from his second procedure and remains physically active without any anginal symptoms. Percutaneous revascularization in patients with ITP remains a challenge and this therapeutic approach, while ultimately successful in the patient, requires further validation.     

Evaluation of a small cadmium zinc telluride detector for scintimammography.

The purpose of this study was to evaluate a small semiconductor-based gamma camera that may have applications in scintimammography. METHODS: A small cadmium zinc telluride (CZT) detector was evaluated. The detector had a field of view of 20 x 20 cm with detector elements of 2.5 x 2.5 mm in size. Both short-bore (35 mm) and long-bore (50 mm) collimators, matched to the geometry of the detector elements, were evaluated. The imaging performance of the CZT detector was compared with that of a conventional gamma camera equipped with all-purpose and ultra-high-resolution collimators. The performance of both systems with respect to breast imaging was evaluated using a water tank containing small glass spheres, 1.8-9.8 mm in diameter. The effects of variations in breast thickness, tumor depth, and tumor-to-background ratio were all simulated in this phantom model. Total counts per image were adjusted to approximate the count density observed in clinical scintimammographic studies. RESULTS: Sensitivity of the CZT detector was 76% that of the equivalent NaI system. The system demonstrated excellent integral uniformity. The energy resolution of the CZT system was 6.5% for (99m)Tc. Spatial resolution with the long-bore collimator was superior to that of a conventional large field-of -view gamma camera equipped with an ultra-high- resolution collimator, over the range 0-6 cm from the collimator face. A blinded review of breast phantom images showed that small spheres (< or =7 mm in diameter) were better seen and had a better tumor-to-background ratio with the CZT system than with the conventional gamma camera. CONCLUSION: A small CZT detector offers superior performance to a conventional gamma camera and should permit reliable detection of breast tumors <1 cm in size.     

Behavioral evidence implicating dopamine in sensorimotor arousal and norepinephrine in the sedative effects of antidepressant drugs

The effects of acute and chronic antidepressant treatment on acoustic startle were evaluated in three experiments. Administration of 2.5–10.0 mg/kg desipramine, amitriptyline, and nortriptyline depressed acoustic startle responding after repeated sensory stimulation. In contrast to the tricyclic drugs, the serotonin reuptake inhibitor zimelidine increased acoustic startle, and inhibition of dopamine reuptake following acute nomifensine and bupropion administration did not influence startle reactivity in the doses examined. The response reducing effects of desipramine and amitriptyline persisted following chronic exposure to these drugs, and these findings were discussed in relation to the inhibitory actions of the tricyclics on locus coeruleus neurons. A second major finding in this study was that animals challenged withd-amphetamine during desipramine and amitriptyline withdrawal showed a facilitated startle response. Enhanced startle reactivity to amphetamine was also observed following long-term exposure to iprindole, and a withdrawal hyperactivity of acoustic startle was evident after chronic treatment with amoxapine, bupropion, and nomifensine. These results agree with evidence that repeated administration of antidepressants increases dopamine neurotransmission which modulates sensorimotor arousal.     

Cell kinetics in acute lymphoblastic leukaemia: comparative analysis between adults and children.

Cell kinetics were studied in 124 patients with acute lymphoblastic leukaemia (ALL) by flow cytometry, comparing cell cycle characteristics between adults (57 cases) and children (67 cases). S, G2 + M and the low protein content fraction of G1 (LPC fraction) were determined and studied in relation to other clinical and biological features. No difference was found between adults and children in the distribution of these variables. The proliferative rates according to organomegaly, leukocytosis, the FAB cytological groups and the immunological groups did not present any significant differences between the two groups of patients. However, cell cycle did seem to have a very different prognostic value for adults and for children. G2 + M was a strong prognostic indicator for childhood ALL: duration of CR and survival were significantly longer when G2 + M was higher (P less than 0.01). In adults, survival was longer for intermediary (between 3.8 and 5.8%) and high (over 7.2%) G2 + M values (P less than 0.01). The negative correlation between S and G2 + M observed in adults and the absence of correlation in children raise the possibility of differences in duration of the different phases for the two groups and perhaps an accumulation of cells in G2 or tetraploidy in some cases.     

Burkitt-type lymphoma in France among non-Hodgkin malignant lymphomas in Caucasian children.

In a retrospective analysis of 87 cases of Caucasian childhood non-Hodgkin malignant lymphoma (NHML) from Lyon, France, all the case were diffuse lymphomas, but 47 were diagnosed as monomorphic small non-cleaved NHML, pathologically indistinguishable from Burkitt''s lymphoma (BL). BL could then be the most frequent childhood lymphoma in France. This homogeneous series allows better definition of the characteristics of BL within NHML. Age distribution is similar to that of endemic BL, with a sex ratio of 3.7/1. Abdominal masses are initially present in 68% of the cases, whereas jaw is involved in only 4%. The disease is characterized by its overwhelming evolution in the absence of therapy. However, complete remission (CR) is usually obtained after the first chemtherapy regimen. Most relapses occur at 3-8 months. Death could be related to cerebrospinal fluid (CSF) involvement, local recurrence or secondary marrow involvement. Ninety per cent of the patients alive with no evidence of disease (NED) 8 months after CR can be considered as definitely cured. Our study on Caucasian children with NHML indicates that, from histological and clinical criteria, nearly half the cases are very similar to African BL. Even though EBV rarely associated with our cases, BL could be a worldwide lymphoma.     

Developmental, behavioral, and opiate receptor changes after prenatal or postnatal β-endorphin, CRF, or Tyr-MIF-1

Developmental and long-term behavioral effects of perinatal injection of beta-endorphin (BE), CRF and Tyr- Pro-Leu- Gly- NH₂ (Tyr-MIF-1) in male rats were investigated along with the possibility that opiate receptors may be altered by the injection of BE during this critical time. Daily injections of peptide were given to pregnant females (100 μg/rat) in the week before birth or to the offspring (50 μg/rat) of untreated mothers during the first week of life. Prenatal BE and CRF reduced body weight on day 1, in contrast to Tyr-MIF-1 which produced a significant increase over controls by day 7 as well as a slight but significant acceleration of eye opening. Among the postnatal treatments, CRF-treated animals showed the most dramatic changes. These included decreased body weight, accelerated eye opening, and, in adulthood, increased open field rearing behavior and a tendency for a monotonic body temperature response to low doses of morphine, in contrast to the biphasic response shown by controls. BE, when given to pregnant mothers, increased the number (B_max) of [³H]naloxone-labeled (mu) receptors in whole brains of offspring assayed on day 14, but it did not significantly alter [³H]d-Ala-d-Leu-enkephalin-labeled (delta) receptors. In contrast, a significant decrease in both mu and delta receptors was observed on day 14 in rats given BE postnatally. These differences in receptors were no longer apparent in adulthood, and no significant differences in tail-flick response were detectable at this time. Nevertheless, some of the effects of these three peptides endured well beyond their presence, and for BE included changes in the number of opiate receptors.     

Alcohol intoxication reduces visual sustained attention

Effects of alcohol intoxication on visual sustained attention were studied using a vigilance task entailing detection of degraded target stimuli. Data were obtained in separate sessions under four ethanol doses, ranging from 0 (placebo) to 1.05 g/kg lean body weight, with periodic maintenance dosing of 0.12 g/kg. Intoxication lowered the overall level of detection performance, and in addition produced dose-related increases in the rate of performance decrement over time. Analysis of performance data using techniques derived from Signal Detection Theory indicated that the decrements were due specifically to alterations in perceptual sensitivity. Examination of eye movements and blinks indicated that the effects of ethanol were not mediated peripherally. Rather, alcohol appears to have deleterious effects on central processing capacity and the availability of capacity over time. The alcohol-related failure of sustained attention may contribute to increased accident risk in tasks requiring continuous performance.