Boletin de estudios medicos y biologicos最新文献

Alzheimer disease, the most prevalent dementia of the aged, is defined by the concurrence of two filamentous brain lesions: neurofibrillary tangles and senile plaques. The lesions are temporally and spatially correlated to each other and to cognitive impairment suggesting that is a interaction between neurofibrillary tangles and senile plaques that might play a role in disease pathogenesis. Here we present findings demonstrating specific interactions between the major protein components of the lesions. Such an interaction is likely important to lesion genesis and to the overall cognitive deficits seen clinically. Also important are forces that stabilize and cement abnormal interactions and protect them form removal. Oxidative post-translational modifications is probably one of the major mediators that by disrupting cellular homeostatic balance both promotes abnormal interactions and makes them resistant to proteolytic removal. Overall, these findings support the view that the lesions of Alzheimer disease are intimately involved in neuronal destructions.

Several forms of cell perturbation have been associated with ethanol ingestion. Fetal alcohol syndrome (FAS) as well as diminished maxillofacial development and inhibition of cell regeneration in vitro and in vivo have been described. Epidermal growth factor (EGF) stimulates maxillofacial growth, DNA synthesis, and it is a potent mitogen for a number of various cell types. EGF exerts its effects on cells through binding to a specific cell surface receptor which leads to activation of a thyrosine kinase in the intracellular part of the receptor. The inhibitory effect of alcohol on EGF in the mouse dental follicle was studied in the offspring of alcoholic mothers using immunocytochemistry. Adult female mice were given 22% alcohol in their drinking water and fed a pelleted diet before and during pregnancy. Maternal blood alcohol levels were 262 +/- 1.3 mg/100 ml on gestation day 12.5. The offspring of the alcoholic and control mice were sacrificed on postnatal day 1.5, their mandibles were dissected, weighed and processed by routine immunocytochemistry with the following results. 1) Significant differences were found in mandible weight p < 0.01 after parturition. 2) The tooth germs in the offspring of ethanol treated mice were morphometrically smaller than those of control littermates. 3) Immunoexpression of EGF in the mandibular first molar of the control group was strong and homogeneous while in the experimental group the expression was light and heterogeneous. It is concluded that maternal alcoholism reduces EGF in the offspring.

Genetic polymorphism is the major contributor that affects human salivary composition. In order to determine the molecular phenotypes in saliva, it is important to know the distribution of proteins with specific functions which allows the clinical diagnosis of specific diseases. Unstimulated human whole saliva samples from 120 subjects were subjected to sodium dodecyl sulfate polyacrylamide slab gel electrophoresis (SDS-PAGE). The phenotype distribution of several molecules including MG1, MG2, alpha-Amylase, PRP-I and cystatins were similar. Qualitative and quantitative characteristics were specific in each subject.

The purpose of this work was to investigate whether the ultradian rhythms that are present prior the electroretinogram (ERG) amplitude circadian rhythm, and are superimposed upon it, during the different stages of development of the crayfish Procambarus clarkii are temperature sensitive, as well as the circadian rhythm. Temperature sensitivity was investigated using ERG amplitude recordings in free running conditions at high and low temperature from juvenile instars of different ages. All recordings were submitted to two types of statistical tests: X2 periodogram and power spectrum analysis. Cycles detected by both methods were selected from periodogram and Q10 was computed. Selected ultradian periods (ranging between 1.7 to 17.5 hrs.) seem to show temperature insensitivity that could imply temperature compensation, a property apparently shared with the emerging circadian period. These results support the endogenous nature of the ultradian ERG rhythms as well as their probably functional interaction with the circadian rhythm.

Structures were found by transmission electron microscopy, they were located within follicular cells and the oocyte, and in the interspace between them in follicles of the teleost fish Betta splendens. Some structures with features characteristic or lamellar bodies were found in small follicles. The possible role of these structures in the formation of the vitelline envelope as well as in the material transference is discussed. Vacuoles, vesticles and particles intensely stained were found in the microvilli and the cortical cytoplasm of the oocyte at the onset of vitellogenesis. These results suggest that different substances present in the cellular components of the follicle might be transferred from cell to cell through the extracellular space and through the prolongations that cross the extracellular space.

Interaction between neonatal undernutrition and the increased self-grooming activity upon hair growth of several body areas was analyzed in rats of 10, 20 and 30 days of age. Light microscopic observations on methylene blue impregnated hairs showed that these perinatal influences delayed the growth of hair follicles and thickness and length of hair measurements of the head and thoracic areas. The hair growth of lateral abdominal regions was less affected. Data suggest that hair alterations are primarily related to food deprivation since hair follicle measures of all skin areas were more affected than the distal hair measurements. Moreover, the distribution of impaired hair growth on different body areas correlates well with the increased self-grooming components associated to neonatal undernourishment.

Timm's impregnated mossy fiber plexus, in five coronal levels throughout the hippocampal complex, of normal and prenatally protein deprived rats at 15, 30, 90 and 220 days of age were analyzed. Morphometric computer assisted image analysis, showed significant decrease in total extent of the mossy fibers area in the prenatally malnourished rats on postnatal day 15 at levels 2, 3, and 4; on day 90 at level 1, and on day 220 at all five levels. This pattern of diet effect is similar to that noted at the same ages in the prior studies of the granule cell dendrites (Brain, Res., 1990; 532:271-277, J. Comp. Neurol, 1991; 310:356-364). This similarity of effects at these loci suggests that the diet effects on the hippocampal trisynaptic circuit are closely linked to each other. In all loci the effect of the diet was most marked on P220, indicating the late appearance of dietary deprivation effects in the hippocampal formation.

Application of a 126 V, 3 Ampers electrical current produces brain death in dogs assessed by irreversible installation of an isoelectric electroencephalogram. Cerebral death was immediate or preceded by a paroxistic activity of short duration (25 +/- 12 Seconds; Mean +/- SD). Besides the isoelectric electroencephalogram, there were immediate respiratory arrest and cardiac fibrillations followed by heart stopping. Reflexes were absent and no response to painful stimuli was observed. An appropriate utilization of the experimental method described in this study may contribute to improve the knowledge about the pathophysiology of cerebral death in humans.

The effects of prenatal and postnatal protein malnutrition on the major and minor somatic axes of the suprachiasmatic nucleus (SCN) cells of the rat were investigated. Female rats were fed either 6%, 8% or 25% casein diet 5 weeks before mating, during gestation and lactation. After weaning the pups were maintained on the same diet until sacrifice at 30, 90 or 220 days of age. The major and minor axes in fusiform, multipolar and ovoid cells were measured in Nissl-stained SCN slices. Although the 8% diet group displayed significant reductions in fusiform and ovoid cells, the 6% diet group showed the most intense reductions in cell size of the three cell types. In the 6% diet group, cell size was significantly lower at 30 days but the difference with the other nutritional groups ameliorated at 90 days and almost reached control values at 220 days. These data suggest that malnutrition maintained during gestation and postnatal life reduces the somatic size of SCN cells. This alteration may be a morphological substrate underlying sleep and behavioral circadian alterations observed in malnourished rats.