The secretion of aspartyl proteinase,a virulence enzyme,by isolates of Candida albicans from the oral cavity of HIV-infected subjects

Prevalence, serotype and in vitro secretion of aspartyl proteinase, a virulence enzyme, were studied in Candida isolates from the oral cavity of 337 HIV-infected subjects. Controls were 95 age-sex-matched HIV- (seronegative) subjects, belonging to either HIV-risk categories (47) or to the normal, general population (48). Fungi were isolated from 155 HIV+ subjects. C. albicans was the most prevalent species (85.8% of all isolates). 94.6% of C. albicans isolates were serotype A and all were agglutinated by a monoclonal antibody (AF1) directed against a major mannoprotein immunogen of the candidal cell wall, confirming previous results with C. albicans isolates from non-immunodeficient subjects. With regard to the stage of HIV infection, there were no statistically significant differences in the incidence of oral Candida carriage between asymptomatic (stage II) HIV+ and HIV- subjects, and between stage II and lymphadenopathic (stage III) individuals. Also, the low (3.8%) incidence of oral candidiasis in the subjects of the latter stage was insignificant with respect to stage II subjects. However, the incidence of C. albicans in stage IV (AIDS) subjects (46.8%) was significantly higher than in all other subjects, and in almost all cases, fungal isolation was accompanied by oral thrush and lower CD4+ lymphocyte counts (< 400 × 10°/L).All isolates of C. albicans were proteolytic in vitro, as assessed by scoring the proteinase activity on BSA agar and monitoring the secreted proteinase antigen by a highly sensitive (1 ng) and specific immunoenzymatic assay. However, by both methods, the isolates from subjects at stages III and IV of infection produced more secretory proteinase than the isolates from either HIV+ asymptomatic subjects or HIV- controls. The differences could not be attributed to particular culture media or source of Candida isolation (carriage versus active infection). Thus, the isolates of C. albicans from advanced HIV infection are serologically similar but more proteolytic than the isolates from earlier stages of HIV infection or those from HIV-uninfected subjects. The apparently higher virulence of C. albicans from AIDS subjects may represent a co-factor in determining and/or aggravating oral candidiasis in these patients.     

Migraine: imaging the aura

We currently conceive of a migraine attack as originating in the brain. Triggers of an attack initiate a depolarizing neuroelectric and metabolic event likened to the spreading depression of Leao. This event activates the headache and associated features of the attack by mechanisms that remain to be determined, but appear to involve either peripheral trigeminovascular or brainstem pathways, or both. The excitability of cell membranes, perhaps partly genetically determined, is the brain's susceptibility to attacks. Factors that increase or decrease neuronal excitability constitute the threshold for triggering attacks. Using a model of visual stress-induced migraine or by studying spontaneous attacks and applying advanced imaging and neurophysiological methods, results have been obtained that support spreading neuronal inhibition as the basis of aura. This neuroelectric event is accompanied by hyperoxia of the brain, possibly associated with vasodilation. Evidence has also been obtained that the spreading cortical event can activate the subcortical centers possibly involved in nociception and associated symptoms of the migraine attack. Susceptibility to migraine attacks appears to be related to brain hyperexcitability. These newer techniques of functional neuroimaging have confirmed the primary neural basis of the migraine attack with secondary vascular changes, reconciling previous theories into a neurovascular mechanism.     

The midvastus surgical approach in total knee arthroplasty

We report a study of 2 surgical approaches to the knee in 42 consecutive patients undergoing a total arthroplasty. They were divided into 2 groups. In Group 1 (n=17) the knee was exposed through classic medial parapatellar arthrotomy and in Group 2 (n=25) the knee was approached through the fibers of the medial vastus. Preoperative assessment did not reveal any statistical differences between the groups, and blood loss, operation time, biochemistry values and radiographic evaluation were also similar. However, a higher number of lateral releases, a loss of knee extension and a reduced range of motion were significantly associated with classical parapatellar arthrotomy. As the number of operative or postoperative complications was not increased, we recommend the mid-vastus approach for total knee arthroplasty.

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Résumé  Nous présentons une étude de 42 arthroplasties totales consécutives de genoux qui ont été divisées en deux groupes. Le groupe 1 (n=17) a eu une voie d’abord classique par arthrotomie antéro-interne parapatellaire et le groupe 2 (n=25) a eu un abord à travers les fibres du vastus medialis. Entre les deux groupes, il n’y a pas de différence significative entre les données pré-opératoires, la perte sanguine, le temps opératoire et l’état radiographique. Dans le groupe 1, un plus grand nombre de libérations externes a été nécessaire, une perte de la force d’extension a été notée ainsi qu’une diminution de l’amplitude articulaire. Comme le taux de complications opératoires et postopératoires n’a pas été majoré, nous recommandons ce type d’approche à travers les fibres du vastus medialis pour l’arthroplastie totale de genou.

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Accepted: 3 January 2000     

Giant intracranial aneurysm of the anterior communicating artery treated by direct surgical approach. Case report

We report the singular case of an exceptionally large giant communicating artery aneurysm successfully treated with a direct surgical approach. The clinical presentation was a relatively short history of frontal headache. In the pre- and postcontrast CT scans the lesion mimicked an intracranial tumor. At surgery the intraluminal thrombus was partially removed with an ultrasonic surgical aspirator; the decompression allowed the isolation and subsequent temporary dipping of the tracts A1 and A2 of both the anterior cerebral arteries. It was then possible to complete the thrombectomy and to dip the neck of the aneurysm. The report emphasizes the indispensable role of MRI for the accurate diagnosis of giant intracranial aneurysms and the recent improvement of the surgical results concerning this category of aneurysms (mainly related to the present wider availability of technical surgical instrumentation).