Biomedical subjects

N Amiridze

Publications and source records attributed to N Amiridze.

4 recordsLinked to original sources

PubMed2000

Evidence that kynurenine pathway metabolites mediate hyperbaric oxygen-induced convulsions.

Metabolism of tryptophan (TRP) through the kynurenine (KYN) pathway in brain, liver, and kidney produces intermediates including the neuroactive agonist quinolinic acid (QA) and the antagonists kynurenic acid (KA) and anthranilic acid (AA) for N-methyl D-aspartate (NMDA) receptors in the central nervous system. We hypothesized that elevated concentrations of QA, KA, or AA can moderate the convulsions that are observed during exposure of rats to hyperbaric oxygen (HBO). We found that i.p. administration of TRP or KYN (both of which cross the blood-brain barrier) had no effect on HBO-induced seizures. However, AA (administered i.p.) or gavage administration of the KYN pathway blocking drug Ro 61-8048, both of which enter the brain from the circulatory system, affect the time to first convulsion and/or coma during HBO in a manner consistent with a modulatory role for seizure activity.

Animals↗

PubMed2000

Decompressive craniotomy in medically uncontrollable malignant infarction.

Patients with progressive neurological deficit following large cerebral infarctions are viewed to have a uniformly poor prognosis. We present two patients with large middle cerebral artery infarctions in which a decompressive craniotomy was life saving and resulted in functional outcome. The clinical course of patients with malignant infarction and the treatment issues involved including patient selection and the timing and extent of cranial decompression are discussed.

Adult↗

PubMed1999

Hydroxyl radicals detected via brain microdialysis in rats breathing air and during hyperbaric oxygen convulsions.

Microdialysis was done on 300-400 g, awake, male rats with microdialysis probes inserted through guide cannulas into the striatum (Bregma co-ordinates A 0.5, L 2.9, D -4.0 for guide cannulas implanted 5 days previously). Rats were exposed to hyperbaric oxygen (HBO; 6 atm absolute, 5 atm gauge pressure of oxygen with carbon dioxide absorbed by soda lime). Artificial cerebrospinal fluid (CSF) containing 5 mM sodium salicylate was perfused at 1 microl/min and collected over sequential 10 min intervals with rats breathing air, then HBO, and after decompression. Times to convulsions and duration and severity of convulsions were observed and recorded. CSF samples were analyzed for 2,3- and 2,5-dihydroxybenzoic acid (DHBA), reaction products of hydroxyl radicals with salicylate, by HPLC and compared to authentic standards. Recovery of DHBAs was 48% from fluid surrounding microdialysis probes, based on in vitro tests. The average time to the first convulsion was 21 min and rats convulsed an average of 4 times during 40 min in HBO. There were no significant differences in hydroxyl radical production by this protocol during any of the 10 min collection periods in air or HBO (average in pmoles for 10 microl of all samples: 2,3-DHBA = 7.0 +/- 2.5 and 2,5-DHBA = 11.3 +/- 4.1). The failure to detect an increase in hydroxyl radicals in HBO prior to or during convulsions appears valid since each rat served as its own control.

Air↗

PubMed1997

The transcallosal interforniceal approach to the third ventricle: anatomic and microsurgical aspects.

OBJECTIVE: The ability to visualize median-sagittal brain structures by magnetic resonance imaging improves planning for surgery to treat lesions of the third ventricle. The most appropriate path to the third ventricle is the transcallosal approach. The present study was undertaken to describe the surgical anatomy and landmarks encountered during this approach. METHODS: The transcallosal-interforniceal approach was undertaken in 30 formalin-fixed brains using an operating microscope. The surface landmarks for the approach pathway were the two points, P5 and P7, located 5 and 7 cm anterior to the central sulcus, respectively. Using these two points on the cortical surface as references, a variety of measurements were made to provide quantitative information about distances between brain structures that are encountered during the surgical approach. Measurements that were made include the following: 1) the distance between P5 and the cingulate sulcus, 2) the distance between the cingulate sulcus and the corpus callosum, 3) the height of the corpus callosum, 4) the distance between the anterior commissure and the foramen of Monro, and 5) the distance between the lower margin of the corpus callosum and the fornix. RESULTS: Mean values for these key measurements were as follows: 1) 23.96 mm (range, 15.0-32.0 mm); 2) 13.50 mm (range, 8.0-20.0 mm) with reference to P5 and 12.73 mm (range, 16.0-18.0 mm) with reference to P7; 3) 6.12 mm (range, 4.0-8.0 mm) with reference to P5 and 6.60 mm (range, 4.0-9.0 mm) with reference to P7; 4) 4.96 mm (range, 2.5-10.0 mm), independent of P5 and P7; and 5) 8.46 mm (range, 3.0-16.0 mm) with reference to P5 and 11.04 mm (range, 6.0-22.0 mm) with reference to P7. CONCLUSION: The detailed quantitative information obtained in this study about the interforniceal approach permitted definition of surgical approach pathways that preserve important anatomic structures, such as the motor strip, genu of the corpus callosum, fornical commissure (hippocampal commissure), anterior commissure, and fornical columns. The approach through this surgical corridor can easily be planned and performed in individual cases using median-sagittal magnetic resonance imaging scans.

Adult↗