Decreased leptin uptake in hypothalamic nuclei with ageing in Wistar rats

Leptin interacts with specific receptors in hypothalamic nuclei and modulates energy balance. Growing evidence has shown the association of obesity and hyperleptinaemia with non-insulin-dependent diabetes mellitus and insulin resistance. The aged Wistar rat shows peripheral insulin resistance in the absence of obesity and alterations of glucose homeostasis. However, it is not known whether, in these animals, the leptin action is altered. Here we studied the effect of ageing on plasma leptin concentration and the ability of hypothalamic nuclei to capture i.c.v.-injected digoxigenin-labelled leptin. Our data indicate that 24-month-old animals are hyperleptinaemic. However, daily food intake was greater in old animals, suggesting that they are leptin resistant. Leptin uptake in the hypothalamus was reduced in old rats. This uptake was a receptor-mediated process as demonstrated by displacement. Leptin accumulation in hypothalamic nuclei was partially colocalized with neuropeptide Y fibres. Immunohistochemical and western blot analyses showed a lower amount of the long form of leptin receptors in the hypothalamus of aged rats. Analysis by RT-PCR also demonstrated a decreased expression of leptin receptor mRNA in old animals. We conclude that the lower leptin uptake may be explained, at least in part, by a decreased amount of receptors in hypothalamic neurones of the aged rats.

Memory and learning disturbances in multiple sclerosis. MRI lesions and neuropsychological correlation

Thirty-five patients with definite multiple sclerosis (MS) were studied. They underwent neuropsychological testing and magnetic resonance imaging (MRI). The MRI findings at different brain areas levels were compared with the neuropsychological findings. A quantitative system was used to measure MRI-MS lesions. In this series, a positive correlation was established between memory and learning disturbances measured by Battery 144, and the lesions measured by MRI (total, hemispheric and, particularly, periventricular lesions). MRI can detect MS lesions, and this study shows that a correlation between MRI and neuropsychological findings is possible if quantitative methods are used to distinguish different MS involvement areas in relation to neuropsychological tasks. These findings suggest that hemispheric lesions in MS produce cognitive disturbances and MRI could be a useful tool in predicting memory and learning impairment.

[Correlation between magnetic resonance and disability scales (EDSS and ISS) in multiple sclerosis]

In the present study the lesions in MRI imaging were quantified and compared with the clinical and functional abnormalities in 56 patients (27 females and 29 males) with definite multiple sclerosis (MS). The evolution was relapsing in 30, there were relapses followed by progressive evolution in 10, and evolution was progressive from the onset in 16. A good correlation was found between the disability scale EDSS and total lesions in MRI (r = 0.45), and also with the disability scale EDSS and hemispheric (r = 0.45) and centrioval (r = 0.41) involvements and with lesions near the third ventricle (r = 0.32). The clinical parameters predicting a greater surface of involvement in MRI were late onset (beyond 45 years) and progressive evolution. The best correlation between disability scale and MRI lesions was found between EDSS and periventricular (lateral ventricles) lesions (r = 0.46). The linearly correlation between both disability scales was good (r = 0.86), but it improved when an exponential equation was used (r = 0.91). This could allow to use the more simple scale (ISS) with a mathematical transformation. When the patients with a greatest surface of involvement were compared with the remaining MS patients, significant differences were found for nearly all evaluated disability items. Patients with greater involvement surfaces in MRI had greater disability.

Pilomatrix carcinoma: role played by MR imaging

We report the magnetic resonance imaging (MRI) of a pilomatrix carcinoma. We found a soft tissue tumor of the back entering the spinal canal and compressing the spinal cord and we monitored a good response to radiotherapy and chemotherapy. We have concluded that MRI played an important role in determination of the volume, extension and management of this rare malignant tumor.