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Changes of mitochondrial membrane proteins in rat cerebellum during aging
No full textQualitative and quantitative changes of mitochondrial membrane proteins during aging were investigated. Free (non-synaptic) mitochondria were purified from rat cerebellum at different ages (4, 8, 12, 16, 20, and 24 months). Mitochondrial outer membrane (OM), inner membrane (IM) and matrix (MX) were separated and the proteins were extracted and analyzed by gel-electrophoresis. After staining, the gels were scanned densitometrically to quantify the proteins. No significant changes in the quantity of OM or MX protein subunits were observed, while several statistically significant quantitative changes in IM proteins with age were found. These age-dependent modifications of inner membrane mitochondrial proteins may play an important role in energy transduction, transport systems and regulatory enzymatic activities in mitochondri
Influence of aging and exogenous substances on cerebral energy metabolism in posthypoglycemic recovery
No full textIn rats of different ages, acute severe hypoglycemia with isoelectric EEG induced extensive deterioration of the energy state and gross alteration of amino acid contents. During recovery of adult animals, tissue glucose concentration returned to normal, while the rate of glycogen synthesis was slow, both lactate and pyruvate concentrations increasing above normal. In the recovery period of "adult" rats, the ATP concentration increased but the adenine nucleotide pool remained reduced, even if the ADP and AMP concentrations were close to normal. Phosphocreatine was restored to normal concentrations with reciprocal changes in creatine content. In adult rats, during the recovery there was a rise in glutamate and glutamine concentrations, gamma-aminobutyrate concentration returning to normal value. Ammonia and aspartate decreased below normal, while alanine increased above normal. Aging does not affect the cerebral metabolic derangement occurring in severe hypoglycemia, but rather the metabolic changes that the brain tends to reverse during the posthypoglycemic restitution. In fact, there was lower restitution of the concentrations of cerebral cortical metabolites of "mature" and "senescent" rats in comparison with "adult" ones. Particularly, in older brains the concentrations of many amino acids and adenylate nucleotides remained largely abnormal. The effect of some agents on the posthypoglycemic recovery was tested: (a) dihydroergocristine; (b) eburnamonine; (c) raubasine; (d) almitrine; (e) piracetam. During the posthypoglycemic recovery, these different agents exhibited different interferences on glycolytic metabolites, amino acids and energy-rich phosphates. However, a more limited effect of the tested agents, which decrease with aging, was observe
Effect of aging on cerebral cortex energy metabolism in hypoglycemia and posthypoglycemic recovery
No full textSevere hypoglycemia, causing the cessation of spontaneous EEG, induced in cerebral cortex of rats of different ages, causes gross energy failure and extensive derangement of both carbohydrate and amino acid contents. During posthypoglycemic recovery of adult rats, there was moderate restitution of energy metabolism and both ATP concentration and adenine nucleotide pool remained still reduced, even if the creatine phosphate and ADP contents were close to normal. During recovery of adult rats there was a rise in glutamate and glutamine concentrations and the perturbated aspartate and gamma-aminobutyrate cerebral contents normalized. Ammonia content decreased to normal, while alanine content was markedly elevated. Aging does not affect the cerebral metabolic derangements occurring in severe hypoglycemia, but rather the metabolic changes that the brain tend to reverse during the posthypoglycemic restitution. In fact, there was lower restitution of the contents of cerebral cortical metabolites of "mature" and "senescent" rats in comparison with "adult" ones. Particularly, in older brains the contents of many amino acids and adenylate nucleotides remained largely abnorma
Action of L-acetylcarnitine on age-dependent modifications of mitochondrial membrane proteins from rat cerebellum
No full textProtein patterns of mitochondrial outer membrane, inner membrane, and matrix from non-synaptic (free) mitochondria from rat cerebellum at different ages (4, 8, 12, 16, 20, and 24 months) were analyzed by gel electrophoresis. Acute L-acetylcarnitine treatment was performed by a single i.p. injection (100 mg/kg body weight) of the substance 60 min before the sacrifice of the animals. Different age-dependent changes were obtained for the proteins of the three fractions. The amount of some protein subunits increased and/or decreased after drug treatment. In particular, protein composition of the inner mitochondrial membrane showed significant age-related modifications. This result probably indicates differences in protein synthesis and/or turnover rates in the various mitochondrial compartments during aging. Acute L-acetylcarnitine treatment caused: a high increase in the amount of one inner membrane protein with Mw 16 kDa, at all the ages studied; a decrease in the amount of many other inner membrane proteins; modifications of some matrix proteins. Our results show that in vivo administration of L-acetylcarnitine affects mainly the inner membrane protein composition of cerebellar mitochondri
Nuclear and mitochondrial DNA synthesis and energy metabolism in primary rat glial cell cultures
No full textDNA synthesis in nuclei and mitochondria purified from serum-supplemented rat glial cell cultures at different days after plating was studied. Furthermore in mitochondria, some enzymatic activities related to energy transduction (citrate synthase, malate dehydrogenase, total NADH-cytochrome c reductase, cytochrome oxidase and glutamate dehydrogenase) were measured. For DNA labeling [methyl-3H]thymidine was added to the culture medium at different days after plating. During the culture times studied the specific activity of total, nuclear, and mitochondrial DNA decreased from 8 days in vitro (DIV) to 21 DIV and increased at 30 DIV. The specific activity of nuclear DNA was always higher than that of mitochondrial DNA. The specific activity of the above mentioned mitochondrial enzymes increased from 8 DIV up to 21 DIV and decreased at 30 DIV, suggesting a relationship between the energy metabolism and the differentiation of glial cells in cultur
Age-dependent changes of nucleic acid labeling in different rat brain regions
No full textThe effects of aging on in vivo DNA and RNA labeling and on RNA content in various brain regions of 4-, 12-, and 24-month-old rats were investigated. No difference in [methyl-14C]thymidine incorporation into DNA of cerebral cortex and cerebellum during aging was observed. The ratio of RNA/DNA content significantly decreased from 4 to 24 months of age in cerebral cortex, cerebellum and striatum. RNA labeling decreased by 15\% in cerebral cortex of 24-month-old animals while in the other brain areas examined (cerebellum, hippocampus, hypothalamus, brainstem, striatum) did not change during aging. In the cerebral cortex, the ratio of the specific radioactivity of microsomal RNA to that of nuclear RNA, determined by in vivo experiments, was not affected by the aging process. A significant decrease of total, poly(A) RNA and poly(A) RNA content was observed in the same brain area of 24-month-old rats compared to 4-month-old ones. Moreover, densitometric and radioactivity patterns obtained by gel electrophoresis of labeled RNA after in vitro experiments (tissue slices of cerebral cortex) showed a different ribosomal RNA processing during aging. In vivo chronic treatment with CDP-choline was able to increase RNA labeling in corpus striatum of 24-month-old animal
Obligatory role of IFN-gamma in induction of lymphokine-activated and T lymphocyte killer activity, but not in boosting of natural cytotoxicity.
No full textThe biological role of the murine IFN-gamma endogenously secreted during cell activation has been probed by the use of a rat mAb (AN18) that specifically neutralizes its activity. When An18 mAb is added to the cultures of BALB/c and C57BL/6 nylon nonadherent spleen cells (naSpc) stimulated for 18 h with 1000 U of IL-2, the normally released IFN-gamma can no longer be detected in the supernatants and the IL-2-induced proliferative response is markedly reduced as compared with control cultures set up in the presence of an unrelated rat mAb. By contrast, the increased natural cytotoxicity is not affected. The 96-h culture of both BALB/c and C57BL/6 naSpc in the presence of 1000 U of IL-2 resulted in marked lymphocyte proliferation and generation of lymphokine-activated killer activity. The presence of An18 mAb strongly inhibited both functions. Similarly, when naSpc were stimulated with mitomycin C-inactivated allogeneic leukocytes in the presence of An18 mAb, the normal proliferative response and specific cytotoxicity were almost abolished, whereas the secretion of IL-2 was in no way affected. Lymphocytes recovered from 3-day cultures stimulated by IL-2 or allogeneic cells in the presence of An18 mAb displayed a decrease of the expression of the p55 chain of IL-2R, as shown by flow cytofluorimetry. Moreover, binding experiments with 125I-labeled IL-2 showed that lymphocytes from allostimulated cultures set up in the presence of An18 mAb display a decreased number of low affinity and almost no high affinity IL-2R as compared with control cultures. These data show that endogenous IFN-gamma plays an obligatory role for the de novo induction of cytolytic activity in lymphokine-activated killer cells and CTL, most probably by affecting the membrane expression of high affinity IL-2R
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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