Impact of Shorter-acting Neuromuscular Blocking Agents on Fast-track Recovery of the Cardiac Surgical Patient

Background: Residual paralysis associated with the use of long-acting muscle relaxants can delay recovery from anesthesia and surgery. The authors tested the hypothesis that use of shorter-acting neuromuscular blocking agents is associated with reductions in tracheal extubation times and intensive care unit (ICU) length of stay in patients undergoing cardiac surgery with cardiopulmonary bypass.

Methods: One hundred ten patients scheduled for elective coronary artery bypass grafting or single valve surgery were randomized prospectively to receive either pancuronium or rocuronium intraoperatively. Anesthetic management and muscle relaxant maintenance dosing were standardized. In the ICU, the time required to wean ventilatory support, the duration of tracheal intubation, and length of stay were recorded. Subjects were asked to quantify generalized muscle weakness as they awakened in the ICU and again after tracheal extubation.

Results: Complete data were collected on 51 patients in the pancuronium group and 52 patients in the rocuronium group. No differences were found between the groups in anesthetic, surgical, or ICU management. Significant increases in the duration of weaning of ventilatory support were observed in patients who received pancuronium (median, 180 min; range, 50-780 min) compared with the rocuronium group (median, 110 min; range, 45-250 min). Tracheal extubation was significantly delayed in the pancuronium group (median, 500 min; range, 240-1,305 min) compared with the rocuronium group (median, 350 min; range, 210-1,140 min). Subjects in the pancuronium group experienced more mild to severe weakness in the ICU. However, the choice of muscle relaxant did not influence ICU length of stay.     

Electrocardiographic Changes in Spontaneous Left Pneumothorax

ABSTRACT. Keller N, Szaff M, Sykulski R (Department of Internal Medicine, Sundby Hospital, Copenhagen, Denmark). Electrocardiographic changes in spontaneous left pneumothorax. Acta Med Scand 1987; 221:499–501. A 25-year-old man was admitted with severe chest pain and an electrocardiogram suggestive of anterior myocardial infarction. Echocardiogram was normal, but chest X-ray showed left-sided pneumothorax. The electrocardiogram showed increasing R-wave amplitude in the days after correction of pneumothorax. Taken in the supine position the electrocardiogram can be misleading in case of pneumothorax or mediastinal emphysema, but the electrocardiogram should be normal if taken in the erect position.     

Neural network models for the gaze shift system in the superior colliculus and cerebellum.

We investigate the role that the superior colliculus (SC) and the cerebellum might play in generating gaze shifts. The discharge of cells in the intermediate layers of the SC is tightly linked to the occurrence of saccades. Many studies have demonstrated that the cerebellum is involved in both eye and head movements. When the head is unrestrained, large amplitude gaze shifts are composed of coordinated eye and head movements. In this study, we propose that the gaze saccades system is controlled by a feedback loop between the SC and the cerebellum. The SC only encodes retinal coordinates and controls the eye displacement (to move the fovea to the target), while the cerebellum deals with the gaze programming and controls the head displacement. When a target appears in space, the buildup cells within the SC decode the target signal in the retina before the saccade onset, and input the signal of the gaze displacement to the cerebellum. The cells in the cerebellum vermis encode the initial position of the eye in the orbit. The gaze displacement is decomposed into the head amplitude and the eye amplitude within the cerebellum. There are two output signals from the cerebellum. One signal controls the head movement. The other is projected back to the SC, and forms a component of the saccade vector to control the eye movement. The sum of the vectors provided by the cerebellum and the vector provided by the burst cells in the SC indicates the direction and the amplitude of the desired movement of the eye during the saccade. We propose a cerebellum model to predict the displacements of the eye and head under the condition that the position of the target signal in the retina and the initial position of the eye in the orbit are known. The results from the model are close to that observed physiologically. We conclude that before gaze shift onset, the cerebellum may play an important role in decomposing the gaze displacement into an eye amplitude and head amplitude signal.     

The frequency of vitamin D deficiency in adults with Crohn's disease.

BACKGROUND: Vitamin D deficiency is a putative, pathogenic cofactor in the increase in osteopenia and osteoporosis seen in patients with Crohn's disease. OBJECTIVE: To determine the frequency of low serum 25-hydroxy-vitamin D3 (25-OHD) levels and the associated alterations in bone mineral density in a cohort of adults with Crohn's disease. METHODS: 25-OHD levels were determined in 242 consecutive patients with Crohn's disease seen in two tertiary inflammatory bowel disease referral centres. Bone mineral density was assessed by dual energy x-ray absorptiometry. RESULTS: Nineteen (8%) patients exhibited vitamin D deficiency (25-OHD less than 25 nmol/L) and 52 (22%) patients exhibited vitamin D insufficiency (25-OHD less than 40 nmol/L). Mean T-scores at the lumbar spine, femoral neck, total hip and ultradistal radius in the group with low 25-OHD did not differ from those of the normal 25-OHD group. Serum alkaline phosphatase and parathyroid hormone levels were higher in the low 25-OHD group than in the normal group. Decreased red blood cell (RBC) folate predicted low 25-OHD in male patients, while smoking, RBC folate and serum iron predicted low 25-OHD in female patients. The rate of low 25-OHD deficiency in the winter was significantly higher than that in the summer (11.9% versus 2.8%, respectively). CONCLUSION: Vitamin D-deficient Crohn's disease patients exhibit biochemical evidence of metabolic bone disease, without detectable differences in bone mineral density. Sunlight exposure, nutrition and smoking status were predictors of vitamin D deficiency in this patient cohort.     

肘关节脱位与肱骨远端关节内骨折

Objective To describe dislocation of the elbow with articular fracture of the distal humerus,a type of elbow fracture-dislocation about which little has been written.Methods Four patients with a dislocation of the elbow and fracture of the distal humerus were identified.Three had dislocation and complex intraarticular fracture of the capitellum,trochlea,and lateral epicondyle.Results Two patients(one treated with a second operation to address avascular necrosis of the capitellum)achieved a functional arc of elbow motion and one patient was lost after removal of the implants 3 months after fracture with documented healing.The fourth patient had a complex open fracture dislocation involving the entire articular surface.An attempt to salvage the articular surface resulted in deep infection.Extensive heterotopic bone led to arthrodesis of the elbow.Conclusions Dislocations of the elbow with articular fracture of the humerus are uncommon.Most injuries involve the capitellum,lateral trochlea,and lateral epicondyle.Open reduction and internal fixation of the distal humerus fracture can restore stability without repairing the medial collateral ligament.     

Global dendritic calcium spikes in mouse layer 5 low threshold spiking interneurones: implications for control of pyramidal cell bursting

Interneuronal networks in neocortex underlie feedforward and feedback inhibition and control the temporal organization of pyramidal cell activity. We previously found that lower layer neocortical interneurones can reach action potential threshold in response to the stimulation of a single presynaptic cell. To better understand this phenomenon and the circuit roles of lower layer neocortical interneurones, we combined two-photon calcium imaging with whole cell recordings and anatomical reconstructions of low threshold spiking (LTS) interneurones from mouse neocortex. In both visual and somatosensory cortex, LTS interneurones are somatostatin-positive, concentrated in layer 5 and possess dense axonal innervation to layer 1. Due to the LTS properties, these neurones operate in burst and tonic modes. In burst mode, dendritic T-type calcium channels boosted small synaptic inputs and triggered low threshold calcium spikes, while in tonic mode, sodium-based APs evoked smaller calcium influxes. In both modes, the entire dendritic tree of LTS interneurones behaved as a 'global' single spiking unit. This, together with the fact that synaptic inputs to layer 5 LTS cells are facilitating, and that their axons target the dendritic region of the pyramidal neurones where bursts are generated, make these neurones ideally suited to detect and control burst generation of individual lower layer pyramidal neurones.     

Ca2+ imaging of mouse neocortical interneurone dendrites: Ia-type K+ channels control action potential backpropagation

GABAergic interneurones are essential in cortical processing, yet the functional properties of their dendrites are still poorly understood. In this first study, we combined two-photon calcium imaging with whole-cell recording and anatomical reconstructions to examine the calcium dynamics during action potential (AP) backpropagation in three types of V1 supragranular interneurones: parvalbumin-positive fast spikers (FS), calretinin-positive irregular spikers (IS), and adapting cells (AD). Somatically generated APs actively backpropagated into the dendritic tree and evoked instantaneous calcium accumulations. Although voltage-gated calcium channels were expressed throughout the dendritic arbor, calcium signals during backpropagation of both single APs and AP trains were restricted to proximal dendrites. This spatial control of AP backpropagation was mediated by Ia-type potassium currents and could be mitigated by by previous synaptic activity. Further, we observed supralinear summation of calcium signals in synaptically activated dendritic compartments. Together, these findings indicate that in interneurons, dendritic AP propagation is synaptically regulated. We propose that interneurones have a perisomatic and a distal dendritic functional compartment, with different integrative functions.     

Bone marrow-derived mesenchymal stem cells in repair of the injured lung

We sought to determine whether an intact bone marrow is essential to lung repair following bleomycin-induced lung injury in mice, and the mechanisms of any protective effects conferred by bone marrow-derived mesenchymal stem cell (BMDMSC) transfer. We found that myelosupression increased susceptibility to bleomycin injury and that BMDMSC transfer was protective. Protection was associated with the differentiation of engrafted BMDMSC into specific and distinct lung cell phenotypes, with an increase in circulating levels of G-CSF and GM-CSF (known for their ability to promote the mobilization of endogenous stem cells) and with a decrease in inflammatory cytokines. In vitro, cells from injured, but not from normal, mouse lung produced soluble factors that caused BMDMSC to proliferate and migrate toward the injured lung. We conclude that bone marrow stem cells are important in the repair of bleomycin-injured lung and that transfer of mesenchymal stem cells protects against the injury. BMDMSC localize to the injured lung and assume lung cell phenotypes, but protection from injury and fibrosis also involves suppression of inflammation and triggering production of reparative growth factors.