Evaluation of the behaviour of a thermal diffusion sensor in a high field strength magnetic resonance system: an experimental study.

Patients with acute brain pathology requiring ferromagnetic bio-medical implants for on-going invasive monitoring are largely excluded from the benefits of MRI scanning. We evaluated the behaviour of a thermal diffusion cortical blood flow (TD-CBF) sensor both in vitro (phantom gelatin model) and in vivo environments in a high field strength MRI system.Two baboons underwent cranial subdural implantation of 2 TD-CBF sensors/hemisphere and a single left parietal sensor was implanted subcortically to determine any deleterious effects. Using standard MRI sequences, artefact size, thermal effects, current generation, movement and reliability of recordings were assessed during scanning.The deflection forces were negligible, no observable thermal effects were demonstrated, while wide fluctuations in cerebral blood flow recordings were recorded. Mean image artefact size for implanted sensors was 6 times larger than in vitro. Patients with an implanted TD-CBF sensor may be safely imaged provided the device is disconnected. The MRI images obtained are of an acceptable quality.     

Serial circulating vasopressin levels in children with septic shock.

BACKGROUND: Septic shock is an important cause of death in pediatric intensive care units. Initial evaluations have shown that vasopressin may have a role in catecholamine refractory shock in adults. It is important to determine whether children with septic shock have deficiency of vasopressin. This will help in defining the role of vasopressin in septic shock. DESIGN: Prospective cohort study. SETTING: Pediatric intensive care unit of a tertiary care hospital in north India. PATIENTS: Patients were children with septic shock, and controls were children with sepsis but no shock. STUDY DESIGN: Vasopressin levels in plasma were determined by enzyme-linked immunosorbent assay for children with septic shock at diagnosis (baseline) and thereafter at 24, 48, and 96 hrs to determine the time trends. The baseline vasopressin values for children with septic shock were compared with those for children without shock. RESULTS: The median (95% confidence interval) vasopressin level at baseline in children with septic shock was 116 (63.3-130.7) pg/mL, and in children with sepsis but no shock it was 106 (61.7-131.77) pg/mL. The median value for survivors was 76 (44.6-130.9) pg/mL, and for nonsurvivors, 118 (81.7-259) pg/mL (p = .16). The serial values also did not show any significant changes; the values at 24 hrs (n = 17), 48 hrs (n = 16), and 96 hrs (n = 15) were 105 (76.1-125.9), 105 (41.4-155.5), and 109.5 (54.9-154.8) pg/mL, respectively. CONCLUSIONS: The results of our study suggest that vasopressin levels are elevated in children with septic shock and that serial values up to 96 hrs do not show any decline.     

Relationship of knee joint proprioception to pain and disability in individuals with knee osteoarthritis.

Proprioception plays an integral role in neuromotor control of the knee joint and deficits in knee joint proprioception are well documented in individuals with knee osteoarthritis (OA). However, the functional relevance of these deficits is not clear. This cross-sectional study evaluated the relationship between knee joint proprioception and pain and disability in a large cohort of individuals with knee OA. Two hundred and twenty participants (145 F, 75 M) with symptomatic knee OA were recruited from the community. Five non-weight bearing active tests with ipsilateral limb matching responses were performed at 20 degrees and 40 degrees flexion to measure knee joint position sense. Pain and disability were assessed by self-reported questionnaires and objective measures of balance and gait. Results showed little association between knee joint position sense variables and measures of pain and disability (r values <0.24, most p>0.05). When comparing participants with the worst and best joint position sense, no significant differences in pain and disability could be found (p>0.05). While our study design does not allow causality to be established, these results suggest that deficits in joint position sense may be due to factors other than pain and that deficits are not large enough to impact upon disability.     

Behçet's disease and cardiac arrhythmia

Summary Only few cases of cardiac conduction disturbances and arrhythmias have been reported in Behçet's disease. We recently observed the case of a 16-year-old woman with Behçet's disease in whom cardiac arrhythmia became the main clinical symptom. This observation and a review of the literature led us to the conclusion that arrhythmia could represent the clinical manifestation of an underlying myocarditis due to Behçet's disease and can be regarded as a feature of cardiac involvement of the disease.     

"Crack smoke" is a respirable aerosol of cocaine base

The smoking of cocaine base [corrected] ("crack") has emerged as a significant substance abuse problem. A detailed characterization of cocaine smoke is a prerequisite for studies of its pharmacokinetics, abuse potential and toxicity. Model pipes were used to generate cocaine smoke analogous to that inhaled by human "crack" abusers. Using procedures to minimize pyrolysis, cocaine base smoke was determined to be 93.5% cocaine particles with the remainder being cocaine vapor. The average particle size generated from all model pipes was 2.3 mu which is small enough to ensure deposition into the alveolar region of the human lung. Although this particle size is eminently respirable [corrected] by primates, a much smaller fraction will reach the alveolar region of rodents. Special generating procedures would therefore be required to expose rodents to meaningful doses of airborne cocaine that mimic the rapid absorption achieved by "crack" smokers.