Brainstem white matter integrity is related to loss of consciousness and postconcussive symptomatology in veterans with chronic mild to moderate traumatic brain injury.

We investigated associations between DTI indices of three brainstem white matter tracts, traumatic brain injury (TBI) injury characteristics, and postconcussive symptomatology (PCS) in a well-characterized sample of veterans with history of mild to moderate TBI (mTBI). 58 military veterans (mTBI: n = 38, mean age = 33.2, mean time since injury = 90.9 months; military controls [MC]; n = 20; mean age = 29.4) were administered 3T DTI scans as well as a comprehensive neuropsychiatric evaluation including evaluation of TBI injury characteristics and PCS symptoms (e.g., negative mood, dizziness, balance and coordination difficulties). Tractography was employed by seeding ROIs along 3 brainstem white matter tracts (i.e., medial lemniscus-central tegmentum tract [ML-CTT]; corticospinal tracts [CST], and pontine tegmentum [PT]), and mean DTI values were derived from fractional anisotropic (FA) maps. Results showed that there were no significant difference in FA between the MC and TBI groups across the 3 regions of interest; however, among the TBI group, CST FA was significantly negatively associated with LOC duration. Additionally, lower FA of certain tracts-most especially the PT-was significantly associated with increased PCS symptoms (i.e., more severe vestibular symptoms, poorer physical functioning, and greater levels of fatigue), even after adjusting for PTSD symptoms. Our findings show that, in our sample of veterans with mTBI, tractography-based DTI indices of brainstem white matter tracts of interest are related to the presence and severity of PCS symptoms. Findings are promising as they show linkages between brainstem white matter integrity and injury severity (LOC), and they raise the possibility that the pontine tegmentum in particular may be a useful marker of PCS symptoms. Collectively, these data point to important neurobiological substrates of the chronic and complex constellation of symptoms following the 'signature injury' of our combat-exposed veterans.

Small-scale experimental study of vaporization flux of liquid nitrogen released on water.

A small-scale experimental study was conducted using liquid nitrogen to investigate the convective heat transfer behavior of cryogenic liquids released on water. The experiment was performed by spilling five different amounts of liquid nitrogen at different release rates and initial water temperatures. The vaporization mass fluxes of liquid nitrogen were determined directly from the mass loss measured during the experiment. A variation of initial vaporization fluxes and a subsequent shift in heat transfer mechanism were observed with changes in initial water temperature. The initial vaporization fluxes were directly dependent on the liquid nitrogen spill rate. The heat flux from water to liquid nitrogen determined from experimental data was validated with two theoretical correlations for convective boiling. It was also observed from validation with correlations that liquid nitrogen was found to be predominantly in the film boiling regime. The substantial results provide a suitable procedure for predicting the heat flux from water to cryogenic liquids that is required for source term modeling.

[Predictive value of positive and negative results of the Widal and Felix test for typhoid fever in general practice in Niamey]. / Valeurs prédictives positive et négative du test de Widal et Félix dans la fièvre typhoïde en médecine générale à Niamey (Niger).

INTRODUCTION: Typhoid is a common reason for seeking medical care in general practice in the developing countries, Use of the Widal and Felix test is frequent in this setting. The purpose of this study carried out in private general medicine clinics in Niamey, Niger was to determine the incidence of typhoid and the predictive value of positive and negative results of the Widal test. MATERIAL AND METHOD: We used low published values of sensitivity (67.9%) and specificity (93.8%). Estimation of the incidence of typhoid was based on reports made to the national health information system of Niger by 3 private clinics in Niamey. RESULT: A total of 1725 persons attended the clinics between 1/12/07 and 31/01/08, including 311 presenting nonspecific signs suggesting typhoid, i.e., at least fever and headache, and 172 presenting typhoid. The incidence was 9.97% in attendees overall and 55.31% in attendees with nonspecific evocative signs. The positive predictive value of the Widal and Felix test was 53.81% and the negative predictive value was 96.35% in attendees overall and 93.13% and 70.25% respectively in patients with clinical signs. CONCLUSION: Other diagnostic modalities such as PCR, coproculture, and hemoculture can be proposed, but are not available in this setting. The positive predictive value of the Widal test among patients with nonspecific signs suggesting typhoid is high. While not negligible, the negative predictive value in this high-incidence group is relatively low and should indicate monitoring.

Infraclavicular brachial plexus block versus humeral approach: comparison of anesthetic time and efficacy.

UNLABELLED: Most upper arm regional anesthesia techniques are successful and differences in efficacy should not dictate the choice of technique. In the present study, we compared humeral block (HB) and infraclavicular brachial plexus block (ICB) using anesthetic time (i.e., duration of the procedure + onset time) as the primary outcome measure. The block was successful when a complete sensory block was obtained in the four major nerves of the arm, and the time to complete block was recorded. Patients undergoing orthopedic surgery of the upper limb were included in a prospective randomized study and received ICB (group I, n = 60 patients) or HB (group H, n = 60 patients). Total anesthetic time was 19.5 min (95% confidence interval [CI], 17.4-21.6 min) for ICB and 20.8 min (95% CI, 18.7--22.9 min) for HB (not significant). Time to perform the block was 4.5 min (95% CI, 4-5 min) for ICB and 9.8 min (95% CI, 8.9--10.7 min) for HB (P < 0.05). The onset time was 15 min (95% CI, 13-17 min) for ICB and 11 min (95% CI, 9--13 min) for HB (P < 0.05). The success rate was 92% for ICB and 95% for HB (not significant). One self-limited vascular puncture was made in each group. HB had a faster onset time but ICB using a double-stimulation technique was faster to perform. Anesthetic time was similar with the two techniques. IMPLICATIONS: We have compared infraclavicular brachial plexus block (ICB) with humeral block. Efficacy and anesthetic time were not significantly different, although time to perform the block was shorter with the ICB.

The epidemiology of myasthenia gravis, Lambert-Eaton myasthenic syndrome and their associated tumours in the northern part of the province of South Holland.

We studied the epidemiology of myasthenia gravis (MG) and the Lambert-Eaton myasthenic syndrome (LEMS), and their association with small cell lung carcinoma (SCLC) and thymoma, in a well defined region of the Netherlands. Available data on all the patients with MG, LEMS, thymoma or SCLC living between 1 January 1990 and 31 December 1999 in the northern region of South Holland, with a population of 1.7 million inhabitants, were evaluated. A total of 202 patients with MG (20 with thymoma) and ten patients with LEMS (seven with SCLC) were identified. LEMS was 46 times less prevalent (2.32 x 10(-6)) than MG (106.1 x 10(-6)), whereas the annual incidence rate of LEMS was 14 times lower (0.48 x 10(-6)) than of MG (6.48 x 10(-6)), reflecting the poor survival of LEMS patients with SCLC. SCLC was diagnosed in 1593 patients, seven (0.44 %) of whom developed LEMS. Mean age at diagnosis of SCLC was significantly lower in SCLC patients with LEMS (p = 0.006). A thymoma was diagnosed in 32 patients, of whom the ten patients with MG (31 %) had a younger age at diagnosis of thymoma than the patients without MG (p = 0.27). This study confirms the increasing prevalence of MG over the last few decades as reported by others, and underscores the relative rarity of LEMS. The frequency of LEMS in our patients with SCLC was lower than reported in previous studies. In patients with a SCLC or thymoma, the tumour was diagnosed at younger age in those who had the associated myasthenic syndrome.

Studies on the role of dopaminergic systems in morphine-induced motor activity. Comparison with noradrenergic and cholinergic systems.

The role of dopaminergic, noradrenergic and cholinergic systems in morphine-induced motor activity was investigated in mice using both blockers and stimulators of the receptors of the respective systems. The dopaminergic blocking drugs, spiroperidol and clothiapine, significantly reduced while stimulating dopaminergic receptors with amantadine significantly increased morphine-induced motor activity. Blockade of noradrenergic receptors with phenoxybenzamine and cholinergic receptors with atropine significantly reduced morphine activity whereas stimulation of either of these systems with DOPS and physostigmine respectively, had no effect. These data suggest that a dopaminergic system mediates morphine-induced motor activity and that this can be modified by interrupting either noradrenergic or cholinergic systems.