Histology and histopathology Vol.17, nº 2 (2002)
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- PublicationOpen AccessEffect of heparin and antivenom on skeletal muscle damage produced by Bothrops jararacussu venom(Murcia : F. Hernández, 2002) Calil-Elias, S.; Martinez, A.M.B.; Melo, P.A.We examined the effect of treatment with heparin and polyvalent antivenom on mice muscle Extensor digitorum longus (EDL) regeneration, after damage induced by injection of B o t h rops jara ra c u s s u crude venom over the muscle of the right posterior limb. The mice were separated into groups and each group received treatment, by intravenous route with either high molecular weight heparin (H), low molecular weight heparin (LMWH), polyvalent antivenom (PAV) or with the combination of PAV plus H or PAV plus LMWH at 15 minutes and 4 hours after the injection of the venom. Myotoxicity was measured by the increase in plasma creatine kinase (CK) activity at two hours after the injection of the venom. The histological changes in EDL at 1, 3, 7 and 21 days after the injection of the ve n o m were analyzed by light microscopy. In each group the normal and regenerated muscle fibers were quantifi e d using Scion Image computer program. We also evaluated in vitro, the influence of these substances in the proteolytic and phospholipase activities of the ve n o m . Heparins decreased the proteolytic activity of the venom but did not affect its phospholipase activity. However the PAV antagonized both activities. PAV and its combinations showed antimyotoxic activity, according to the magnitude of CK plasma levels. At 21 days the r egeneration was observed in all animals, also in those that received only the venom. All treatments, ex c e p t LMWH, promote a significant increase in the number of muscle fibers.
- PublicationOpen AccessIntergenic mRNAs. Minor gene products or tools of diversity?(Murcia : F. Hernández, 2002) Finta, C.; Warner, S.C.; Zaphiropoulos, P.G.The general model of gene e x p r e s s i o n implies that the units of genetic information, the genes, constitute the basis of the mRNA and protein products detected in living organisms. It is well known that in eukaryotic cells a single gene may give rise to va r i o u s gene products due to alternative splicing and/or different positions of transcriptional start and termination. H ow eve r, recent experimental results suggest that in addition to this variation in gene expression, another l evel of complexity may also exist as evidence for the presence of mRNAs that combine sequence information ( exons) from distinct genes is accumulating. Moreove r, the mechanisms that allow this production of intergenic mRNAs are starting to unravel and it appears that these f o l l ow two general pathways: (a) bypass of transcriptional termination, resulting in the generation of bicistronic pre-mRNAs; and (b) authentic trans-splicing events between pre-mRNAs of distinct genes.
- PublicationOpen AccessImmunogold localization of mitochondrial aspartate aminotransferase in mitochondria and on the cell surface in normal rat tissues(Murcia : F. Hernández, 2002) Cechetto, J.D.; Sadacharan, S.K.; Berk, P.D.; Gupta, R.S.Mitochondrial aspartate aminotransferase (mAspAT) (E.C. 2.6.1.1), an important enzyme in amino acid metabolism, is identical to a fatty acid-binding protein (FA B Pp m) isolated from plasma membranes of several cell types. Employing a monospecific polyclonal antibody to rat mAspAT, we have used immunogold electron microscopy to study the subcellular distribution of mAspAT in various mammalian tissues. Immunogold labeling of rat tissue sections embedded in LR Gold resin showed strong labeling of mitochondria in all tissues examined (viz. live r, pancreas, pituitary, spleen, heart, kidney, submandibular gland). In addition, strong and specific labeling was also observed at a number of non-mitochondrial sites including various locations in k i d n ey, such as on cell surface in distal tubules and cortical collecting ducts, in condensing vacuoles, along cell boundaries between adjoining cells, and in endothelial cells lining capillaries in the glomerulus. S u r face labeling due to mAspAT was also seen in arteriolar endothelial cells and in lymphocytes. These findings support the previous identification of mAspAT as both a mitochondrial enzyme and a plasma membrane protein. It is suggested that in accordance with its established role in other cells and tissues, the surfa c e - located mAspAT in kidney and endothelial cells is i nvo l ved in the fatty acid transport process. The duallocalization of mAspAT, as well as a large number of other mitochondrial proteins (viz. Hsp60, Hsp10, Cytochrome c, TRAP-1 and P32 (gC1q-R)) in recent studies, within both mitochondria and at various specific extramitochondrial sites raises fundamental questions about the role of mitochondria in cell structure and function, and about the mechanisms that exist in normal cells for protein translocation from mitochondria to other compartments. These results have implications for the role of mitochondria in apoptosis and different diseases.
- PublicationOpen AccessEffects of cigarette smoke exposure on the utlrastructure of the golden hamster parathyroid gland(Murcia : F. Hernández, 2002) Yano, R.; Hayakawa, D.; Emura, S.; chen, H.; Ozawa, Y.; Taguchi, H.; Shoumura, S.Cigarette smoking has been identified as one of the risk factors to induce osteoporosis. However, we find no study on the morphology of the parathy r o i d gland under smoking exposure. We studied the ultrastructure of the parathyroid gland, lung and femur of the golden hamster exposed to cigarette smoke. Fourweek- old male hamsters were housed in a plastic case (48x31x30 cm) and were exposed to cigarette smoke for 12 weeks, 5 minutes exposure, 4 times a day, 4 days a week. There were no differences in serum calcium level and the whole bone mineral density between the control and the smoke-exposed groups. In the parathyroid gland of the smoke - exposed animals, the Golgi complexe s associated with many prosecretory granules were well d eveloped and many secretory granules were located near the plasma membrane. Large lipid-like inclusion bodies were observed in the alveolar macrophages of the smoke-exposed animals. The femur morphology showed a wider area of resorbing surface in the smoke-exposed group than in the control group. From these findings, it is conceivable that the secretory activity of the p a r a t hyroid gland was stimulated with cigarette smoke exposure.
- PublicationOpen AccessMembrane electropermeabilization effects of frequency and membrane surface order on liposome leakage(Murcia : F. Hernández, 2002) Neitchev, V.; Terezova, N.; Matsumura, H.; Tomov, T.Liposomes containing fluorescence marke r were exposed to an alternating electric field of 80 V peak to peak square electric waves at diff e r e n t frequencies 0.01, 1, and 100 kHz to perturb the liposome permeation. The efflux of fluorescence dye after application of the electric field was measured by recording the fluorescence emission due to the complex formation reaction between the fluorescence dye and calcium ions in the bulk medium solution. Two independent sets of experiments were conducted: 1) calcium ions were present during electropulsation; and 2) they were added after electric field application. Two parameters, fluorescence emission intensity and increment of temperature of the solution in the chamber, were studied. The effect of membrane surface order on the fluorescence dye leakage from the liposomes wa s studied by addition of urea at threshold concentration before the liposomes sealed. The data demonstrate the existence of frequency dependency window at 1 kHz. Furthermore, the data were interpreted according to the theory of interactions of electromagnetic fields with highly polarized and deformed materials such as liposome particles. The urea caused an enhancement of the fluorescence dye leakage at frequency of 100 kHz. This effect could be explained as a decrease of the membrane binding rigidity due to the disordering effect of urea on the membrane lipid surface. Our conclusion is that the frequency and the membrane surface order are additional parameters that influence the processes of membrane electropermeabilization.