Quantitative morphology of human glioblastoma multiforme microvessels: structural basis of blood-brain barrier defect

Summary Neoplastic invasion of the brain parenchyma results in a disruption of the ultrastructure of the blood vessel walls such that serum proteins extravasate into the surrounding tissue, resulting in cerebral edema. The structural changes involved are not well understood, since the pores through which serum constituents pass (permeability routes) in normal barrier vessels and in tumor vessels where the barrier is compromised, have not been extensively explored. In this study we investigate the ultrastructure of human brain microvessels in biopsied samples of control brain tissue and five glioblastoma multiforme tumors. Electron micrographs of a total of 78 vessels were analysed with computer assisted morphometry for ultrastructural evidence of permeability routes. Fenestrations in the endothelium were not seen. Pinocytotic vesicle number and arrangement did not differ significantly from that seen in control brain vessels. Interendothelial junctions with enlarged distensions (which may represent sections through transendothelial channels) were seen in some vessels from most tumors but not in control barrier vessels. In addition, large gaps in the endothelial layer were seen in less than two percent of tumor vessels. In conclusion, glioblastoma multiforme vessels in this study show subtle alterations in vessel morphology from that seen in controls. We suggest that the high vascular permeability and resultant brain edema seen in glioblastoma multiforme tumors is likely due to the presence of channels through interendothelial junctions, and rare but large breaks in the endothelial wall.     

Reflex sympathetic dystrophy in brain-injured patients.

One-hundred consecutive patients were prospectively evaluated on admission to our Brain Injury Unit for signs and symptoms of reflex sympathetic dystrophy (RSD) in the upper extremity. Patients averaged 4 months postinjury and had an average age of 29 years. Thirteen patients had clinical signs and symptoms of RSD and were then evaluated with standard radiographs and 3-phase radionuclide scintigraphy. Twelve of 13 patients had 3-phase bone scans (TPBS) consistent with RSD (12% overall incidence). RSD was present exclusively in the spastic upper extremity. There were 9 patients with hemiparesis and 3 with quadraparesis. There was a significantly higher (P < 0.01) incidence of associated upper extremity injury in the group with RSD (75%). All patients had a mean Rancho Cognitive Level of V and initial Glasgow Coma Scores less than 8. Patients who developed RSD had lower Glasgow Coma Scores than the non-RSD patients. Brain-injured patients often display agitation, hyperalgesia, disuse or neglect of the RSD-involved extremity. In addition, these patients are often cognitively unable to vocalize complaints of pain. Undiagnosed RSD in these patients can result in a significant delay in rehabilitation and possible loss of the use of an otherwise functional upper extremity.     

Complications of surgical endoscopy

Background: This study examines the notion that gastrointestinal endoscopy performed by supervised surgical residents is safe. Methods: We reviewed all gastrointestinal endoscopic procedures performed by surgical residents with faculty supervision for complications and deaths occurring up to 30 days following the procedures. Results: The overall complication rate for 9,201 upper and lower endoscopy procedures was 1.4% and 0.42%, respectively. Overall mortality rate was 0.76% for upper endoscopy and 0.6% for lower endoscopy. No mortality was a direct result of a procedure-related complication. Intestinal perforation, drug overdose, bleeding, and aspiration were the most common procedure-related complications. Each resident completed an average of 75 upper endoscopies and 79 lower endoscopies during their training period. Conclusions: Gastrointestinal endoscopy can be performed safely by surgical residents with appropriate supervision. The higher morbidity and mortality of upper endoscopy are most likely related to the underlying disease rather than the procedure. Awareness of common complications and application of appropriate precautions and instruction are critical for minimizing complications. Received 25 March 1996/Accepted: 24 April 1996     

Performance characteristics and image fidelity of gray-scale monitors.

Gray-scale monitors are an essential element of electronic radiology, and their ability to provide images that are perceived to be identical to those available on conventional or laser-printed film is crucial to success of electronic radiology. Image fidelity is measured in physical characteristics (luminance, dynamic range, distortion, resolution, and noise) and with psychophysical techniques, including receiver operator characteristics analysis with clinical images and testing with contrast-detail patterns to determine threshold contrast. Currently, laser-printed images facilitate greater information transfer than does a gray-scale monitor because of their higher absolute luminance (500 ft-L vs 60 ft-L), greater perceived dynamic range, and better spatial resolution. In the near future, the developments of gray-scale monitors with 150-200 ft-L luminance, a display standard based on just noticeable differences, and algorithms to improve similarities between gray-scale display images and laser-printed images will help increase the acceptability of monitors as a means to make primary diagnoses.     

Implementation of a successful endovascular surgical program in a non-teaching tertiary-care centre in Ontario.

Endovascular surgical techniques have become an accepted standard of care for high-risk patients with abdominal aortic aneurysms and for certain patients with thoracic aortic pathology and peripheral arterial aneurysms. In Canada, endovascular surgery has been concentrated in tertiary-care academic teaching institutions. As the technology evolves and as expertise advances, the applicability of endovascular techniques will expand. With time, and as the demand for endovascular techniques rises, this expertise will increasingly need to be delivered by dedicated vascular surgical services in nonteaching institutions. The dissemination of endovascular surgical capabilities represent a unique challenge. We report the successful implementation of an endovascular surgical program in a tertiary-care nonteaching institution using a carefully planned preceptorship model. We review our initial 49 cases and discuss 6 factors important to the successful establishment of an endovascular surgical service: education, teamwork, strict selection of patients, use of a single stent-graft manufacturer, industry support and endovascular preceptorship. Our experience may be used as a model by other institutions in Canada.     

The impact of near-patient testing on the organisation and costs of an anticonvulsant clinic

A near-patient testing facility was provided at an anticonvulsant clinic and compared with the previously offered service. Productivity was increased by over 20%, with savings in medical and nursing staff time. This saving in time is offset by increased consumable costs but still enables a significant net saving.