Upsala journal of medical sciences. Supplement最新文献

Four questions are addressed: - 1. What are the immediate effects of undernutrition on developing brain likely to be and what are they? 2. Can any general statement be made about vulnerability of developing brain to undernutrition? 3. To what extent are the immediate effects recoverable on refeeding? 4. Do any attenuating or compensatory mechanisms operate? 1. IMMEDIATE EFFECTS: It is worth stating what is almost axiomatic, because it is often forgotten, that undernutrition is likely to affect only those processes which are contemporaneous with it (plus some that follow it). This is borne out by the available evidence. There appears to be little or no destruction of existing structures by undernutrition. 2. GENERAL STATEMENT ON IMMEDIATE EFFECTS: The novel general statement is examined that undernutrition affects the growth rate of all processes contemporaneous with it to the same extent. This is found to have considerable generality. The possible, though perhaps illusory exception of myelination is discussed. Uniform growth restriction gives rise to distorted brain growth through interaction of the timing of different brain growth processes with the timing of undernutrition. 3. EXTENT OF RECOVERY: Recovery is considered in terms of true catch-up: diminution in absolute deficit. The extent of recovery on refeeding varies from none, through partial, to complete, depending on the process under consideration and the timing and severity of the undernutrition. 4. POSSIBLE COMPENSATORY MECHANISMS: Intrinsic to the animal include altered cell cycle characteristics, delayed development, that all of these operate to a greater or lesser extent, during or after undernutrition, thus reducing the magnitude of effects and facilitating recovery.

Animals (rats, gerbils and guinea pigs) were exposed to various common solvents. The brain lipids were extracted and analysed. In particular the fatty acid pattern of a major phospholipid, ethanolamine, phosphoglyceride was studied. A major finding was that some chlorinated solvents, trichloroethylene, perchloroethylene and 1,1,1-trichloroethane, had effects on the ethanolamine phosphoglyceride fatty acid pattern, while most other solvents, like toluene, xylene, white spirit and Freon 11 lacked this effect. Relatively small, but significant, changes were observed in the proportions of the polyunsaturated fatty acids of both the n-6 and n-3 series. The selective effect of the chlorinated solvents might indicate that they have a specific effect on the enzymatic regulation of membrane fatty acid composition. However, the lack of effects of other solvents might also be explained by low blood levels, due either to a low uptake (Freon 11, white spirit) or an extensive metabolism (toluene, xylene). Intrauterine exposure of guinea pigs to perchloroethylene (160 ppm) during the last half of gestation had minor effects on the ethanolamine phosphoglyceride fatty acid pattern. Thus it appears that animals during the period of rapid brain growth are equally sensitive to exposure as adult animals.

The historical background of lipid research with particular reference to the nervous system is outlined. Attention is called to the early studies of Swedish investigators on the morphology and physical properties of the lipid rich myelin sheath. The pioneering research of the late Gunnar Brante on quantitative topical lipid chemistry of the human nervous system in health and disease is pointed out. A selection of lipid histochemical methods for various spingolipids is presented. Results are reported of their application to cases of four genetically determined sphingolipidoses. The morphological changes characterizing these diseases are interpreted in terms of histochemistry and biochemistry. The recently developed method by Dowson for the characterization of autofluorescence emission spectra from neuronal lipopigment in various ceroidoses (ceroid-lipofuscinosis) has been applied to cases of Sanfilippo's syndrome and Salla disease. The results are briefly commented upon.

A consistent finding in epidemiological studies of mild mental retardation (MMR) is a somewhat higher prevalence of boys than girls. Our own study in Aberdeen agreed with these findings. Examination of the numbers of boys and girls at different levels of retardation within our study population revealed the greatest excess at the highest IQ levels of greater than or equal to 75. This was found to be true in other studies as well. Since this IQ range is above the generally agreed upon cut-off point used to classify children as MMR, these findings suggest that boys remaining in regular classes may be having more difficulty in school performance than girls. Possible reasons for this are examined.