MRI and stereotaxis. Choice of an approach route on an independent console.

The authors report their experience of cerebral stereotaxis for biopsy purposes. Since January 1990, they have been using MRI which provides vascular images and makes it possible to simulate surgical procedures beforehand. The authors have developed a specific program on an independent console. MRI sections are acquired with a 1.5 Tesla Sigma (G.E.) apparatus in 3DFT volume and T1-weighted SPRG sequence, after gadolinium injection. The sections are memorized and reconstructed by a SUN computer. After automatic recognition of the referential of a Leksell G plane, the target and the puncture vector are chosen by a radiologist and a neurosurgeon. The X, Y, Z co-ordinates of the point of puncture and the angles of penetration into the cerebral volume are delivered automatically. Provided the entire measurement chain is constantly tested and corrected if necessary, the precision of the system is of the order of one millimetre.     

A magnetic resonance imaging study of putamen nuclei in major depression.

The basal ganglia are recognized as putative mediators of certain cognitive and behavioral symptoms of major depression. Moreover, patients with basal ganglia lesions have repeatedly exhibited significant affective symptomatology, including apathy, depressive mood, and psychosis. Using high resolution, axial T2 intermediate magnetic resonance images, and a systematic sampling stereologic method, we assessed putamen nuclei volumes in 41 patients with major depression (DSM-III) and 44 healthy volunteer controls of similar age. Depressed patients had significantly smaller putamen nuclei compared with controls. Age was negatively correlated with putamen size in both groups. These results are the first demonstration of diminished putamen volumes in depression and further support a role for basal ganglia structures in the etiopathogenesis of depression.     

Evidence of somatotopic organization of the sensory thalamus based on infarction in the nucleus ventralis posterior.

BACKGROUND: This is to describe a restricted sensory syndrome of unique distribution due to thalamic infarct. CASE DESCRIPTION: We report a case of pure sensory disturbance involving the left intraoral and perioral regions and the tips of the thumb and forefinger of the left hand. Magnetic resonance imaging revealed a small infarct in the contralateral thalamus, presumably affecting the nucleus ventralis posterior. CONCLUSIONS: This patient provides an excellent correlation between clinical findings and thalamic representation of body surface as established during stereotactic procedures.     

Participation of lipid peroxidation in the loss of hepatic drug-metabolizing activities in experimental fascioliasis in the rat

Fascioliasis causes a dramatic decrease in drug-metabolizing ability of the hepatic monooxygenase (MFO) and glucuronosyltransferase (GT) enzyme systems in the rat. The present study was undertaken to determine whether lipid peroxidation is involved in the enzymatic loss. Peroxidative damage of membrane lipids (as assessed by the tissue content of malonic dialdehyde, MDA, and the diene conjugation absorption in microsomal membranes) was found to occur over the entire course of the liver infection (concomitant to a decrease in glutathione levels), and to different degrees in relation to the various steps of the parasite cycle. The onset (MDA six times the controls; delta E 1% = 1.55 at the 20th day) coincides with the beginning of the loss of MFO (-30%) and GT (-20% at the 20th day), and peaks between the 30th and 40th day (MDA eight times the controls; delta E 1% = 1.96), when the loss in the enzyme activities is maximal (MFO - 60/70%; GT - 65/95%). There was a strict correlation at all the observation times between the extent of lipid peroxidation and the decrease in drug metabolizing ability: this supports the view that lipid peroxidation is the major agent in the impairment of MFO and GT enzyme activities, and very likely in the initiation of the pathological degeneration of the liver tissue. As evidenced by histological examination, the phagocytic response of the liver tissue to the parasite invasion and growth leads to oxidative stress, which is the causative agent in the initiation and development of lipid peroxidation.