Nouveautés sur la sclérose en plaques de l''enfant

Pediatric MS is better understood after a series of epidemiological studies including the French cohort following almost 500 children since more than 7 years. Pediatric MS may have an onset as early as 2 years but symptoms are different than those at adolescence. Its evolution towards a motor handicap is slower than in adults but cognitive impairment have to be evaluated carefully. Interferon beta treatment can be use, if needed, even before the age of 10. Several environmental factors might increase its risk, especially early EBV infection or passive smoking. HBV vaccination does not increase significantly its risk of occurrence.     

围产儿与儿童胸腺的病理改变

The most outstanding pathological changes of perinatal babies and children, based on the review of the autopsy files in the 1st Affiliated Hospital of West China University of Medical Sciences, are lymphocytic depletion, and reticuloepithelial cell swelling and/or fusiform malformation in the cortex, while in the medulla apoptosis is more prominent. We suppose that these alterations are due to immaturity of cortical thymocytes, and in the diseased condition, they are easily affected by extraordinary factors, especially the influence of corticosterone inducing acute severe necrosis, so the number of lymphocytes are obviously diminished. But, in the medulla, as intact mature lymphocytes exist, physiological phenomenon such as apoptosis is rather prominent in it. While in the medulla, Hassall's corpuscles have various characteristic changes, such as cornification, calcification, fusion, cystic change and disintegration. Besides, we observed a new alteration in the thymus defined as vacuolization. All the above pathological changes reached the peak in the 28- day group; there after, they might become either worse or better according to the condition of the disease and growth of the body. However, these are still problems to be further studied separately.     

Ultrasonographic findings in gastric cancer: in vitro and in vivo studies

Ultrasonography was performed in 45 cases of gastric cancer. Specimens from all 45 cases of gastric cancer were subjects to ultrasonographic study by the water immersion method for comparison with histology. In 32 of these 45 cases in vivo ultrasonographic evaluation was performed prospectively. The overall accuracy rates for the diagnosis of the depth of cancerous invasion were almost 80% in both in vitro and in vivo studies. In vivo ultrasonographic findings agreed well with those from the specimen studies. Ultrasonography was considered to be useful in the diagnosis of gastric malignancies.     

Single unit activity in the auditory cortex of a monkey performing a short term memory task

Summary Short term memory to tones (STMT) was investigated by recording single unit activity in the auditory cortex of a behaving monkey. The activity of each unit was studied in two behavioral conditions: a) During task performance, the monkey had to compare two tones separated by one second of silence (inter-stimulus interval), b) During a nonperforming period; the monkey heard the two tones but did not respond behaviorally. It was noted that the firing rate of many units during the inter-stimulus interval (ISI) was dependent on the frequency of the first tone. Such dependency was observed even towards the end of the ISI, both during task performance trials (50% of the units) and during the nonperforming period (32% of the units). The activity of these units could be the basis of STMT in both of these behavioral states. In 65% of all the units tested, the responses during the ISI were of a higher magnitude in the performance period than were the responses in the non-performance period. The activity of these units may be related either to general processes such as attention and expectation or to short-term memory processes. During task performance, the responses of 23% of the units to the second tone were dependent on whether its frequency was identical to that of the first tone. Such dependency was never observed during the non-performing period. These units may detect similarity or non similarity between two tones presented one second apart. Periodic patterns of firing were not found in the study, thus suggesting that the ISI responses were not generated by reverberatory activity in simple closed loops. On the basis of these results, several alternative mechanisms of STMT are suggested.     

The acute effects of glucose on the insulin biosynthetic-secretory pathway in a simian virus 40-transformed hamster pancreatic islet beta-cell line

The acute regulatory effects of glucose on proinsulin synthesis at the translational level and the subsequent processing of newly made hormone through the insulin biosynthetic-secretory pathway in a clonal cell line (HIT-T15 cells) of simian virus 40-transformed hamster pancreatic islet beta-cells were examined. Proinsulin synthesis in HIT-T15 cells, assayed by immunoprecipitation, comprised 2.5-5% of the total protein synthesis during a 40-min pulse label period, though preproinsulin mRNA levels were only 0.25-0.29% of the total mRNA. There was no specific enhancement of proinsulin synthesis in response to increasing concentrations of glucose or other tested metabolites or by agents stimulating the cAMP or protein kinase-C second messenger systems during a 40-min pulse label period. Compared to that in normal beta-cells, processing of proinsulin to insulin was markedly retarded. Unlike that in normal beta-cells, newly synthesized hormone in HIT cells was secreted at a very low rate that was not enhanced by a high glucose concentration and was not preferentially secreted compared with preformed hormone. Thus, although a glucose sensor was present in HIT cells, since secretion of preformed insulin stores was stimulated 8-fold between glucose concentrations of 0 and 11 mM, regulation at several stages in the passage of newly made insulin through the biosynthetic-secretory pathway did not display the acute glucose sensitivity seen in normal nontransformed beta-cells.     

Comparison of glomerular and mesangial prostaglandin synthesis and glomerular contraction in two rat models of diabetes mellitus

Enhanced prostaglandin production is postulated to contribute to altered vascular reactivity and glomerular hyperfiltration in early insulin-deficient diabetes mellitus. Rats with streptozocin-induced diabetes (STZ-D) show glomerular hyperfiltration and develop renal disease. BB rats with genetic diabetes (BB-D) also hyperfilter but have only minor renal lesions. We therefore compared glomerular and mesangial prostaglandin E2 (PGE2) production and glomerular contractility in response to pressors as a reflection of in vitro vascular reactivity in these models. Glomeruli isolated from rats with 3 wk of STZ-D produced significantly more PGE2 under basal and ionophore A23187-stimulated conditions than those from control rats. Glomeruli from BB-D rats under basal and stimulated conditions, however, generated amounts of PGE2 that were comparable to either those of nondiabetic littermates or of normal Wistar rats. Mesangial cells cultured from glomeruli of STZ-D, BB-D, and control rats all had identical prostaglandin profiles judged by conversion of [14 C]arachidonic acid. They also produced comparable amounts of PGE2 under basal conditions and after stimulation with angiotensin II or A23187, as determined by radioimmunoassay. Planar surface area of glomeruli isolated from control rats showed a dose-dependent decrease in response to angiotensin II (10(-11)-10(-9) M). This response to angiotensin II was at least as great in glomeruli from STZ-D rats. Contraction of glomeruli from control and STZ-D rats was also comparable after vasopressin or norepinephrine. Similarly, glomeruli from BB-D and BB control rats contracted in a comparable fashion to angiotensin II and norepinephrine.(ABSTRACT TRUNCATED AT 250 WORDS)