Biomedical subjects
Publications and source records attributed to S Jacques.
The authors report a case of bilateral posttraumatic middle cerebral artery occlusion. Previously reported unilateral cases are reviewed and possible pathophysiological mechanisms disscussed.
A major concern in the use of neural prostheses is whether electrical stimualtion can cause irreversible damage to neurons. The Neural Damage Model was devised to study the problem and to provide guidlines. The cerebral cortex of cats was stimulated continuously for 36 hours with balanced, biphasic waveforms. The charge per phase, charge density and current density were varied in 16 separate tests. Of these stimulus parameters the charge per phase was more closely correlatable with neuronal damage than charge density and current density. Furthermore, the findings in this study suggest that current flow is more important than electrochemical reactions in causing neural damage. Correlation between blood-brain barrier (BBB) breakdown and neuronal damage was valid only in the group of animals sacrificed immediately following stimulation. The BBB is restored within one month following electrical injury. Convulsive seizures occurred in all but one of the animals during electrical stimulation. A technique for localizing the electrode sites at autopsy and in the microscopic sections is described.
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Ultrasound has become an important diagnostic tool for management of the obstetrical patient. It is most useful when a pregnancy has shown specific clinical indications, such as diagnosis of multiple pregnancy, assessment of bleeding during pregnancy, and assessment of fetal growth. Recently, ultrasound has been used extensively to diagnose structural anomalies of the fetus. Nurses need to be knowledgeable concerning ultrasound so they can explain the procedure to patients and help allay patients' fears and anxieties.
Neural prostheses activated by radiofrequency transmission are currently being implanted to treat a variety of clinical problems. It is essential that neither the materials used in these prostheses, particularly the electrodes, nor the stimulus parameters that are employed will cause neural damage. The experiences of investigators engaged in both the experimental laboratory and clinical studies of the effects of electrical stimulation are reported herein.
Neurotransplantation has been proposed as a potential treatment for the neurodegenerative disorder of Huntington's disease (HD), which currently has no effective therapy. While patients with Parkinson's disease have received neurotransplantation, until recently no HD patients have undergone transplantation for HD with standardized evaluations of their progress following surgery. The current report presents the cognitive changes in three patients with HD who underwent bilateral transplantation of human fetal striatal tissue. As part of the pre- and postsurgical evaluation, all three patients were administered a neuropsychological battery sensitive to the cognitive effects of HD within 2 mo prior to surgery and at 4-6 mo following transplantation. Four to 6 mo subsequent to surgery, all patients demonstrated increased scores on some measures of cognitive functioning. However, the pattern of changes was not uniform across subjects. These findings suggest that fetal striatal transplantation may improve some of the cognitive symptoms associated with HD in the three reported patients.
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