Human embryonic stem cell neural differentiation and enhanced cell survival promoted by hypoxic preconditioning.

Transplantation of neural progenitors derived from human embryonic stem cells (hESCs) provides a potential therapy for ischemic stroke. However, poor graft survival within the host environment has hampered the benefits and applications of cell-based therapies. The present investigation tested a preconditioning strategy to enhance hESC tolerance, thereby improving graft survival and the therapeutic potential of hESC transplantation. UC06 hESCs underwent neural induction and terminal differentiation for up to 30 days, becoming neural lineage cells, exhibiting extensive neurites and axonal projections, generating synapses and action potentials. To induce a cytoprotective phenotype, hESC-derived neurospheres were cultured at 0.1% oxygen for 12 h, dissociated and plated for terminal differentiation under 21% oxygen. Immunocytochemistry and electrophysiology demonstrated the 'hypoxic preconditioning' promoted neuronal differentiation. Western blotting revealed significantly upregulated oxygen-sensitive transcription factors hypoxia-inducible factor (HIF)-1α and HIF-2α, while producing a biphasic response within HIF targets, including erythropoietin, vascular endothelial growth factor and Bcl-2 family members, during hypoxia and subsequent reoxygenation. This cytoprotective phenotype resulted in a 50% increase in both total and neural precursor cell survival after either hydrogen peroxide insult or oxygen-glucose deprivation. Cellular protection was maintained for at least 5 days and corresponded to upregulation of neuroprotective proteins. These results suggest that hypoxic preconditioning could be used to improve the effectiveness of human neural precursor transplantation therapies.

The use of Mitek anchors to secure mesh in abdominal wall reconstruction.

Abdominal wall complications of TRAM flap breast reconstruction are well described. Synthetic mesh abdominal reinforcement is believed to decrease the incidence of these complications. An innovative technique with commonly available suture anchors has been used in a case of recurrent abdominal laxity after a TRAM flap. Osseous fixation of synthetic mesh with the Mitek GII suture anchor will undoubtedly be used more widely in abdominal wall reconstruction.

Agenesis of the gallbladder revisited laparoscopically.

Gallbladder agenesis is an extremely rare disease. Necropsy incidence has been reported to be 0.016%. Failure to locate the gallbladder at the time of a planned cholecystectomy can be very challenging. We report such a case during a laparoscopic cholecystectomy. The indication for surgery in these patients are complaints of gallbladder symptoms along with a false-positive ultrasound study. During exploration, an abnormal location of the gallbladder has to be excluded. Ectopic gallbladder locations include intrahepatic, lesser omentum, retroperitoneal, retrohepatic, within the falciform ligament, retroduodenal, and retrohepatic areas. Thorough exploration and cholangiography are essential. Embryologically, the gallbladder and cystic duct arise from the caudal portion of the hepatic bud. All of the previously reported cases of gallbladder agenesis have shown an absence of both the gallbladder and cystic duct. We report an embryological oddity wherein a patent cystic duct was found along with an agenetic gallbladder. This is the first case report of this finding, along with this being the first absent gallbladder discovered laparoscopically.

Implications of risk factors in necrotizing fasciitis.

The following risk factors, previously associated with necrotizing fasciitis, were identified in 25 consecutive patients: diabetes mellitus, intravenous drug abuse, age greater than 50, hypertension, and malnutrition/obesity. Additional data recorded included the duration of illness to the time of the first operative procedure, the type of procedure performed, the anatomic location of the infection, the etiology, culture reports, and leukocyte counts. The goal of this study was to determine whether the number of risk factors present in a patient was predictive of mortality. Six patients (24%) died and 19 patients survived. The nonsurvivors exhibited a significantly higher percentage of diabetes mellitus, 83 per cent versus 37 per cent (P = 0.047). Fifteen of 19 survivors (79%) and only one of six nonsurvivors (17%) had fewer than three risk factors (P = 0.006). In conclusion, more than three previously identified risk factors present in patients with necrotizing fasciitis were found to be predictive of a mortality rate of 50 per cent. The mainstay of treatment remains aggressive surgical intervention, broad-spectrum antibiotics, and nutrition support.

Avoiding complications and decreasing costs of central venous catheter placement utilizing electrocardiographic guidance.

A technique for electrocardiographic (ECG) guided percutaneous placement of central venous catheters (CVC) was studied in a prospective, randomized manner. In 34 patients, 51 ECG guided percutaneous CVC were compared with 29 blind percutaneous CVC in 23 patients. Thirty-nine percent of CVC placements were changes over a guide wire. Ideal catheter tip location at the atriocaval junction was achieved in 96 percent of the patients in the study versus 59 percent of those in the control group (p less than 0.001). In addition, we report 25 patients with open placement of CVC using intraoperative ECG guidance and fluoroscopic confirmation. Ideal location of the catheter tip was achieved in 100 percent of these patients. ECG guided CVC placement using the technique described herein obviates the need for catheter repositioning, repeat roentgenographic studies and intraoperative fluoroscopic imaging, along with the attendant costs and radiation exposure to staff and patient. Aberrant catheter tip placement and the associated morbidity are also eliminated.

A comparison between area and volume measurements of the mastoid air spaces in normal temporal bones.

In a study of 26 normal cadaveric temporal bones, a significant correlation was found between the area of the mastoid air spaces assessed from a conventional lateral radiograph and the mastoid volume as determined using high resolution computed tomography. The relationship, which was found to be linear, is of the form V = 0.82 A + 0.13. The correlation coefficient is 0.95 with a residual standard deviation about the regression of 1.14 cm3. It is apparent, therefore, that an accurate assessment of the mastoid air space volume can be obtained by means of a simple and routinely requested investigation, i.e. the 35 degree lateral oblique radiograph.

The influence of temporal bone anatomical variation upon the caloric stimulus.

This study involved a comparison of temperature changes occurring in isolated cadaveric temporal bones as a result of caloric stimulation, with information gained from radiological examination of the bones by means of high resolution computed tomographic scanning. This was performed in order to investigate the complex nature of heat transfer within the temporal bone and the influence which anatomical variations may have upon the accuracy of evaluation of vestibular function by means of the caloric test. No significant correlation could be found between the maximum temperature change occurring across the lateral semicircular canal and any of the parameters obtained from radiological assessment except for the diameter of the internal auditory meatus. It was deduced that an intra-subject difference in the diameters of the internal auditory meatus of 0.5 mm would introduce an absolute error in the evaluation of percentage canal paresis of 10%. Since normal intra-subject differences in internal meatus diameter can exceed 0.5 mm, this finding was considered to be highly significant.

Facial numbness and dysesthesia. New features of carotid artery dissection.

Facial numbness and dysesthesia have not been emphasized as presenting features in spontaneous internal carotid artery dissection. Progressive facial pain, accompanied by oculosympathetic paresis, altered taste, and facial numbness suggest the possibility of basal skull neoplasm. We describe a patient, with previously undiscovered fibromuscular dysplasia, who presented with severe neck and face pain, dysgeusia, oculosympathetic paresis, and markedly reduced facial sensation due to a spontaneous vascular dissection. Altered facial sensation should now be included in the symptomatology of internal carotid artery dissection.