Intracortical circuits, sensorimotor integration and plasticity in human motor cortical projections to muscles of the lower face

Previous studies of the cortical control of human facial muscles documented the distribution of corticobulbar projections and the presence of intracortical inhibitory and facilitatory mechanisms. Yet surprisingly, given the importance and precision in control of facial expression, there have been no studies of the afferent modulation of corticobulbar excitability or of the plasticity of synaptic connections in the facial primary motor cortex (face M1). In 25 healthy volunteers, we used standard single- and paired-pulse transcranial magnetic stimulation (TMS) methods to probe motor-evoked potentials (MEPs), short-intracortical inhibition, intracortical facilitation, short-afferent and long-afferent inhibition and paired associative stimulation in relaxed and active depressor anguli oris muscles. Single-pulse TMS evoked bilateral MEPs at rest and during activity that were larger in contralateral muscles, confirming that corticobulbar projection to lower facial muscles is bilateral and asymmetric, with contralateral predominance. Both short-intracortical inhibition and intracortical facilitation were present bilaterally in resting and active conditions. Electrical stimulation of the facial nerve paired with a TMS pulse 5-200 ms later showed no short-afferent inhibition, but long-afferent inhibition was present. Paired associative stimulation tested with an electrical stimulation-TMS interval of 20 ms significantly facilitated MEPs for up to 30 min. The long-term potentiation, evoked for the first time in face M1, demonstrates that excitability of the facial motor cortex is prone to plastic changes after paired associative stimulation. Evaluation of intracortical circuits in both relaxed and active lower facial muscles as well as of plasticity in the facial motor cortex may provide further physiological insight into pathologies affecting the facial motor system.

Innovative treatment approaches in schizophrenia enhancing neuroplasticity: aerobic exercise, erythropoetin and repetitive transcranial magnetic stimulation

Schizophrenia is a brain disorder associated with subtle, but replicable cerebral volume loss mostly prevalent in frontal and temporal brain regions. Post-mortem studies of the hippocampus point to a reduction of the neuropil constituting mainly of synapses associated with changes of molecules mediating plastic responses of neurons during development and learning. Derived from animal studies interventions to enhance neuroplasticity by inducing adult neurogenesis, synaptogenesis, angiogenesis and long-term potentiation (LTP) were developed and the results translated into clinical studies in schizophrenia. Out of these interventions aerobic exercise has been shown to increase hippocampal volume, elevate N-acetyl-aspartate in the hippocampus as neuronal marker, and improve short-term memory in schizophrenia. The hematopoietic growth factor erythropoetin (EPO) is involved in brain development and associated with the production and differentiation of neuronal precursor cells. A first study demonstrated a positive effect of EPO application on cognition in schizophrenia patients. In randomised controlled studies with small sample size, the efficacy of repetitive transcranial magnetic stimulation (rTMS), a biological intervention focussing on the enhancement of LTP, has been shown for the improvement of positive and negative symptoms in schizophrenia,. The putative underlying neurobiological mechanisms of these interventions including the role of neurotrophic factors are outlined and implications for future research regarding neuroprotection strategies to improve schizophrenia are discussed.

Histopathologic resolution of adult liver transplantation adenovirus hepatitis with cidofovir and intravenous immunoglobulin: a case report

Adenovirus (ADV) infections in adult solid organ transplant recipients, although rare, are associated with high mortality. There are no randomized controlled trials establishing the efficacy of specific treatment modalities. To our knowledge apparent response to treatment with combination therapy with intravenous cidofovir (CDV) and immunoglobulin (IVIG) has only been demonstrated in 2 adult renal transplant recipients in whom ADV was documented in body fluids only. We describe an adult liver transplant recipient diagnosed with ADV hepatitis based on positive immunohistochemical staining of a liver biopsy specimen, positive blood ADV DNA polymerase chain reaction (PCR), and treated with the combination of CDV and IVIG. We demonstrated both clearance of viremia and histopathologic resolution of the hepatitis despite the patient's fatal outcome. To our knowledge this is the only case documenting eradication of tissue-invasive ADV disease in any solid organ transplant recipient using CDV and IVIG. This case provides evidence to support the use of this drug combination, which has many potential toxicities that might discourage its use otherwise.

Aspects of deceased organ donation in paediatrics

Organ transplantation offers children in acute or chronic severe organ failure similar opportunities to adults. However, while the number who might benefit is relatively low, significantly fewer cadaveric donors exist for any given child compared with an adult. Incompatible organ size and relatively low donation rates mean that despite living parental donation and innovations to reduce donated organ size, children die before organs become available. The severity of the UK situation is compounded by restrictions on paediatric living donation, uncertainties over the application of brain death criteria, and ethical concerns about the use of donation after circulatory death. The UK Department of Health's Organ Donation Task Force suggested the means by which the adult donor pool might be increased, recommending that outstanding ethical and legal issues be resolved, but made no specific recommendations about children.

Total antioxidant status and oxidative stress and their relationship to total IgE levels and eosinophil counts in children with allergic rhinitis

BACKGROUND

Oxidative stress may play a role in the pathophysiology of several diseases including allergic rhinitis.

OBJECTIVES

To evaluate whether plasma total oxidant status (TOS) in the form of plasma reactive oxidants differs between children with allergic rhinitis and healthy controls and to investigate associations between plasma antioxidants and other allergic rhinitis-related immunological markers.

MATERIALS AND METHODS

Plasma total antioxidant status (TAS), TOS, total eosinophil count, and total serum immunoglobulin (Ig) E levels were measured in 106 children newly diagnosed with allergic rhinitis and 70 nonallergic children (7-12 years of age). Plasma TAS and TOS were measured using novel automated measurement methods. Blood eosinophils (absolute counts and percentage of total white blood cells) and total IgE were elevated in children with allergic rhinitis after adjusting for age and sex.

RESULTS

TAS and TOS were higher in the patient group than in the control group (P<.001 and P<.002, respectively). The association between plasma TAS and TOS and allergic rhinitis status was similar when eosinophils, total IgE, and allergic sensitization were included as possible confounders in logistic regression models. Multivariate logistic regression identified allergic rhinitis as the only independent factor contributing to TOS.

CONCLUSION

Plasma TAS and TOS levels are elevated in children with allergic rhinitis. Moreover, the high level of TOS indicates that these patients are exposed to severe oxidative stress. This stress factor may have a role in the pathogenesis of allergic rhinitis.

Complication following primary repair of a penetrating bull horn injury to the trachea

A 22-year-old male patient was admitted to the casualty with a bull horn injury in the lower zone of the neck in the midline. The patient was conscious and distressed but hemodynamically stable. Local examination revealed a lacerated wound. He underwent emergency primary repair of the wound under halothane anesthesia; intubation was done keeping in readiness all preparations for difficult airway management. Postoperatively, elective controlled ventilation was performed with continuous infusion of muscle relaxant. After approximately 8 hours of controlled ventilation, the syringe pump failed; this initially went unnoticed and made the patient cough and buck on the tube. Infusion was restarted after a bolus dose of vecuronium bromide intravenously but, meanwhile, the patient developed subcutaneous emphysema in the neck. He was immediately transferred to the operating room, where exploration of the surgical site revealed dehiscence of the tracheal wound; this had led to the subcutaneous emphysema. Repair of the tracheal wound dehiscence was not possible due to both lack of space and lack of tissue for apposition. Hence, a tracheostomy tube was inserted through the tracheal wound and the patient was transferred to the intensive care unit for elective controlled ventilation. The patient was weaned off the ventilator within 24 h and transferred to the surgical ward on spontaneous ventilation with the tracheostomy tube in situ. The size of the patient's tracheostomy tube was reduced gradually by the serial exchange method. The wound ultimately healed with minimal scarring.

Facial Nerve Monitoring under Neuromuscular Blockade

The characteristics of facial nerve electromyography at various levels of neuromuscular blockade are unclear. Partial blockade is well known to facilitate anesthetic safety and management. However, the use of neuromuscular blockage in many skull base procedures is avoided to allow intraoperative facial nerve monitoring.We studied the influence of various levels of neuromuscular blockade on facial nerve stimulation in the New Zealand white rabbit. The facial nerve was exposed in the middle ear of six rabbits. Using electromyographic-type facial nerve monitor, we recorded the facial electromyography signals in these rabbits at increasing levels of vecuronium-induced neuromuscular blockade. All animals demonstrated reliable facial electromyography response at all levels of partial neuromuscular blockade (P < .02). Five of the six animals could be monitored throughout complete blockade. These results clearly demonstrate that rabbit facial electromyography monitoring is possible under neuromuscular blockade. The effect of neuromuscular blockers on facial electromyography monitoring deserves further study, as partial blockade would greatly facilitate the management of anesthesia in otologic, neurotologic, and skull base surgery.

Manipulating atomic fragmentation processes by controlling the projectile coherence

We have measured the scattering angle dependence of cross sections for ionization in p+H2 collisions for a fixed projectile energy loss. Depending on the projectile coherence, interference due to indistinguishable diffraction of the projectile from the two atomic centers was either present or absent in the data. This shows that, due to the fundamentals of quantum mechanics, the preparation of the beam must be included in theoretical calculations. The results have far-reaching implications on formal atomic scattering theory because this critical aspect has been overlooked for several decades.