Biomedical subjects
A Doron
Publications and source records attributed to A Doron.
Infratentorial epidermoids.
Infratentorial epidermoids are rarely seen in the lifetime of a neurosurgeon. Most published series consist of a dozen or so cases. In a period of 20 years we operated on only 6 such patients. Five are doing excellently, one patient died two and a half months after operation of a fulminating infection. The follow-up is of 20 years, 9 years, and 3 years of the first three patients, while the remaining three were operated during the last year. Such an accelerated pace of epidermoid incidence in our department during the last year may be fortuitous, but may also be an indication that, many patients with vague complaints who had an epidermoid, had been missed in the past. Undoubtedly, the CT scan has greatly facilitated the diagnosis of epidermoid cysts, whether infra- or supratentorial. Diagnosis, however, hinges on suspicion or awareness on clinical grounds of the possibility of an infratentorial epidermoid. The analysis of the clinical presentation in our 6 cases, seems to allow the division of infratentorial epidermoids into those that are posteriorly located, which uniformly manifested at some stage of illness raised intracranial pressure, and the anterior epidermoids in the cerebello-pontine angle characterized by the insidious involvement of cranial nerves. Computerized tomography, in some cases with the adjunct of Metrizamide cisternography, confirms the diagnosis and delineates the spread of the lesion.(ABSTRACT TRUNCATED AT 250 WORDS)
Morphological response of injured adult rabbit optic nerve to implants containing media conditioned by growing optic nerves.
Adult rabbit retina can express regeneration-associated characteristics after optic nerve injury, provided it is supplied with appropriate diffusible substances originating from media conditioned by regenerating fish optic nerves or by optic nerves of a newborn rabbit [Hadani et al., Proc. Natl. Acad. Sci. U.S.A., 81 (1984) 7965; Schwartz et al., Science, 228 (1985) 600]. This was shown by applying the active substances to the injured axons in the form of 'wrap-around' implants, consisting of collagen-coated silicone tubes which had been soaked in the conditioned media (CM). The regeneration-associated response was manifested biochemically and by sprouting of nerve fibers in culture. The present work provides morphological evidence that the implantation prolongs survival of ganglion cells and optic nerve fibers and induces new growth. Light microscopic analysis (using horseradish peroxidase (HRP) for labeling the fibers) revealed, 1 week following optic nerve injury, labeled fibers and ganglion cells in both the implanted and control (injured only or injured and implanted with collagen-coated silicone tubes free of CM) nerves. However, from the second week after the injury, distinct differences in the appearance of viable ganglion cells and labeled fibers, were seen between experimental and control preparations. In sections taken through the optic nerve, at the region distal to the site of injury, HRP-labeled fibers were seen in the experimental nerves 1 week, 2 weeks and to a significantly lesser extent 1 month after injury.(ABSTRACT TRUNCATED AT 250 WORDS)
Effects of low-energy He-Ne laser irradiation on posttraumatic degeneration of adult rabbit optic nerve.
Axons of the mammalian peripheral and central nervous systems degenerate after nerve injury. We have recently found that He-Ne laser irradiation may prevent some of the consequences of the injury in peripheral nerves of mammals. In the present study, the efficacy of the laser in treating injured neurons of the mammalian CNS was tested. Optic nerves of adult rabbits were exposed daily for 8-14 days to He-Ne laser irradiation (14 min, 15 mW) through the overlying muscles and skin. As a result of this treatment, the injured nerves maintained their histological integrity, which is invariably lost in injured mammalian CNS neurons.
Age related decline in aluminum-activated human platelet adenylate cyclase: post-receptor changes in cyclic AMP second messenger signal amplification in normal aging and dementia of the Alzheimer type.
Low, micromolar concentrations of aluminum (in the presence of NaF) were shown to strongly activate human platelet adenylate cyclase and provided a useful probe for evaluating cyclic AMP second messenger function distal to the receptor: The effect of normal aging and disease state on second messenger activity in man was studied by measurements of the aluminum-activated enzyme. A significant decline in aluminum-stimulated platelet adenylate cyclase activity in older, healthy subjects was observed. An age-associated decline in NaF-stimulated cyclic AMP synthesis was also demonstrated for normal, non-demented subjects. These findings suggest an age-associated lesion at the level of the guanine nucleotide regulatory protein/catalytic subunit of the adenylate cyclase complex. However, for patients with Alzheimer's disease no such decline in platelet adenylate cyclase activity was detected, and increased sensitivity to both aluminum and NaF was demonstrated.
Medical students and their views on psychiatric issues.
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