Biomedical subjects

V Pointillart

Publications and source records attributed to V Pointillart.

22 records · Page 2Linked to original sources

PubMed1994

[Bases for drug therapy of spinal cord injuries].

The initial lesion after spinal cord injury is due to two types of lesions: "primary" and "secondary". Aim of drug treatment is the limitation of the secondary lesion to facilitate recovery at the injury site. Mechanisms involved in the secondary lesion are of two types: a "macroscopic" one due to the compression of the cord and the ischemia due to hypoxia and fall of arterial blood pressure, a "microscopic" one due to biochemical and enzymatic phenomena. In those, glutamate liberation, intracellular calcium modifications, free radical synthesis and lipid peroxidation are the more fashionable. Numerous drug treatments are proposed which will never take the place of immediate resuscitation care and cord decompression.

Female↗

PubMed1993

Effects of nimodipine on posttraumatic spinal cord ischemia in baboons.

Posttraumatic ischemia appears to be largely responsible for the extension of lesions in acute injury of the spinal cord. In the present study, we have evaluated the putative improvement of axonal function by the calcium channel blocker nimodipine after acute trauma of the spinal cord. Three techniques were used: (1) spinal cord blood flow (SCBF) using a scanographic technique with stable xenon, (2) somatosensory evoked potentials (SEPs), and (3) magnetic resonance imaging (MRI). Thirteen baboons were used in this study. Acute trauma was achieved by compression of the spinal cord at level L1 by applying pressure for 5 sec with an inflated balloon catheter injected with Ringer's solution. Following the injury, one group (n = 5) received a saline infusion (placebo) for seven days, and a second group (n = 8) received a nimodipine infusion (0.04 mg/kg/h) during the same period of time. SCBF and SEP were first recorded prior to trauma. SCBF, SEPs, and MRI were then recorded on the day of the injury and eight days prior to histologic examination of the spinal cord. In these studies nimodipine significantly improved SCBF. The decrease in SCBF observed at day one and day eight following trauma was significantly reduced in the treated group. Two baboons in the treated group also showed improvement of axonal function as assessed by SEP. No significant difference was observed with MRI, however, histologic study revealed that the lesions were significantly smaller in the treated group. Based on these observations we conclude that a week of nimodipine treatment following spinal cord injury enhances SCBF, limits the size of the spinal cord lesion, and perhaps improves functional recovery.

Animals↗

PubMed1992

[Methods for measuring spinal cord blood flow].

This study aimed to review the techniques used most currently for measuring spinal cord blood blow flow (SCBF) in animals, i.e. the hydrogen clearance, labelled microspheres, 133Xe clearance and 14C-antipyrine autoradiographic methods. All four techniques may only be used in animals, because of their invasiveness. Flow figures varied greatly with the method, the spinal level at which measurements were carried out, and the species of animal. However, results tend to suggest that SCBF is very similar to cerebral blood flow in that it is controlled by chemical, autoregulatory and metabolic factors. Approaches to measuring SCBF in man may be made using stable xenon-enhanced computed tomographic imaging (Xes-CT) in the same way as for measuring cerebral blood flow. The calculation of SCBF is based on Fick's principle transformed by Kety and Schmidt. After a reference CT section has been obtained, twelve 8 mm thick sections are carried out whilst the patient breathes a 30% xenon-70% air/oxygen mixture. This series of views enables the SCBF to be calculated in four steps. Quantitative analysis in eight human subjects gave a mean SCBF of 58.8 +/- 5.96 ml x 100 g-1 x min-1. However, this method has a low signal to noise ratio. Moreover, the qualitative analysis of the parametric views of flow demonstrate tissue heterogeneity, partly due to the patient's movements (breathing movements). However, the method is non invasive, safe, and reproducible. As it can measure very low values of blood flow, the study of ischaemic spinal lesions is made possible, although some technical and software improvements are still required.

Adult↗

PubMed1992

[Effects of continuous administration of nimodipine during the acute phase of spinal cord injury in baboons].

This study was carried out to assess the putative improvement of spinal cord blood flow obtained with a calcium channel blocker after acute spinal cord injury in ten baboons. The injury was generated by compressing the cord at L1 level for 5 seconds with a balloon catheter inflated to 2 bars with Ringer's solution. Subsequently, five monkeys received a saline infusion, and five others a nimodipine infusion (0.04 mg.kg-1 x h-1), for seven days. Spinal cord blood flow (SCBF) was measured using a scanographic technique with stable xenon. Somatosensory evoked potentials (SEP), magnetic resonance imaging (MRI) and a histological study of the spine were carried out a different times of the study. SCBF and SEP were recorded before injury. Thereafter SCBF was measured every thirty minutes during the four hours following the injury, as well as on day 7. SEP and MRI were recorded on days 1 and 7. The histological study was carried out on the eighth day. Three spinal cord and vertebral segments were collected, fixed, sliced and stained. SCBF before injury was not significantly different in either group (39.8 +/- 15.9 ml x 100 g-1 x min-1 for the treatment group 40.9 +/- 16.3 ml x 100 g-1 x min-1 for the control group). During the injury, there were major variations between animals. The results were expressed as percentages of each animal's control SCBF (before injury). Immediately after injury, SCBF increased in both groups. However, in the control group, SCBF decreased more than in the treatment group on the seventh day after injury (80 to 90% vs 25 to 50%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗