Characteristics of interhemispheric relationships in the absence or presence of a skill

A comparative analysis of the time and amplitude characteristics of the negative N200 and positive P300 components of visual evoked potentials recorded at symmetric points of the frontal, parietal, temporal, and occipital areas of the right and left hemispheres of the cerebral cortex has been performed in subjects with or without the skill of operating a computer. Subjects inexperienced in an operator’s work exhibited an interhemispheric difference in the time and amplitude characteristics of the studied components. In subjects that had the skill of operating a computer, the interhemispheric difference was little, which suggests that the cortex plays only a small role in the cerebral control of this activity.     

Dinitrosyl iron complexes with glutathione largely relieve rats of experimental endometriosis

A study was made of the effect of binuclear dinitrosyl iron complexes (DNIC) with glutathione in rats with experimental endometriosis. The latter was induced in an autotransplantation model, where two fragments of endometrium with myometrium (2 × 2 mm) from the left uterine horn were grafted to the inner surface of the anterior abdominal wall. After 4 weeks, the test animals received i.p. injections of 0.5 mL DNIC-glutathione at a dose of 12.5 μmol/kg daily for 12 days. This treatment more than halved the total volume of endometrioid tumors. Remarkably, tumor growths from grafts in control rats were often attended by tumors spontaneously arising nearby or in other locations; no such secondary tumors were observed in DNIC-treated animals. The EPR signal with g _av = 2.03 characteristic of protein-bound DNIC with thiol ligands was recorded in liver and endometrioid implants of control as well as treated animals. Activation of ribonucleotide reductase, detected by a doublet EPR signal at g = 2.0 with 2.3-mT hyperfine splitting, was found in small tumors. The beneficial effect of DNIC-glutathione was suggested to be due to DNIC breakdown near the tumors, with release of a large amount of molecular nitric oxide and nitrosonium ions that resulted in selective local cytotoxicity.     

Mice with deletion of the mitochondrial glycerol-3-phosphate dehydrogenase gene exhibit a thrifty phenotype: effect of gender

To define the role of mitochondrial glycerol-3-phosphate dehydrogenase (mGPD; EC 1.1.99.5) in energy balance and intermediary metabolism, we studied transgenic mice not expressing mGPD (mGPD-/-). These mice had approximately 14% lower blood glucose; approximately 50% higher serum glycerol; approximately 80% higher serum triglycerides; and at thermoneutrality, their energy expenditure (Qo(2)) was 15% lower than in wild-type (WT) mice. Glycerol-3-phosphate levels and lactate-to-pyruvate ratios were threefold elevated in muscle, but not in liver, of mGPD-/- mice. WT and mGPD-/- mice were then challenged with a high-fat diet, fasting, or food restriction. The high-fat diet caused more weight gain and adiposity in mGPD-/- than in WT female mice, without the genotype differentially affecting Qo(2) or energy intake. After a 30-h fast, WT female lost 60% more weight than mGPD-/- mice but these latter became more hypothermic. When energy intake was restricted to 50-70% of the ad libitum intake for 10 days, mGPD-/- female mice lost less weight than WT controls, but they had lower Qo(2) and body temperature. WT and mGPD-/- male mice did not differ significantly in their responses to these challenges. These results show that the lack of mGPD causes significant alterations of intermediary metabolism, which are more pronounced in muscle than liver and lead to a thrifty phenotype that is more marked in females than males. Lower T(4)-to-T(3) conversion in mGPD-/- females and a greater reliance of normal females on mGPD to respond to high-fat diets make the lack of the enzyme more consequential in the female gender.     

Influence of aggressive computer games on the brain cortex activity level in adolescents

Dynamic changes in the activities of different areas of the brain cortex were studied in order to determine cortical structures responsible for playing aggressive computer games, with the degree of initial aggression of the adolescent subjects taken into account. Changes in anxiety and aggression produced by aggressive computer games were found to depend on the initial level of aggression of the subjects. In adolescents with a high baseline level of aggression, the amplitude of the N200 component increased in the frontal and decreased in the temporal areas of the cortex, whereas, in adolescents with a low baseline aggression level, N200 decreased in the frontal and increased in the temporal cortical areas.     

Effects of the Execution of a Maze Task on Regulatory Mechanisms of the Autonomic Nervous System in Subjects with Different Levels of Nonverbal Intelligence

The effects of spatial task performance on heart rate characteristics were studied taking into account nonverbal intelligence and autonomic balance. Males and females with low nonverbal intelligence according to the Raven test were mostly sympathicotonics, while subjects with high intelligence were mostly vagotonics. A specific emotional response was observed in females with low and high nonverbal IQs immediately after the task completion and increased the stress index (SI). This clearly suggested that the task was stressful for them. Males with low and high nonverbal IQs were characterized by a reduction of the SI, indicating that this task activity was adequate for male subjects.__________Translated from Fiziologiya Cheloveka, Vol. 31, No. 3, 2005, pp. 50–54.Original Russian Text Copyright © 2005 by Grigoryan, Stepanyan, Agababyan, Arakelyan, Arutyunyan.     

Ouabain blocks some rapid concentration-induced clamp acetylcholine responses onHelix neurons

1. The effects of ouabain, a potent inhibitor of Na(+)-K+ ATPase, were determined on the transmembrane responses of internally dialyzed Helix neurons to rapid acetylcholine (ACh) application using the "concentration clamp" technique. 2. Ouabain selectively depressed "A"-type responses to ACh, which are due to a selective increase in membrane permeability to chloride. In contrast, the "B"-type responses, due primarily to an increase in monovalent cation permeability, was unaffected. 3. The blockade of the Cl- responses was not associated with a change of the reversal potential of the response. Ouabain depressed the maximal response without shifting the dose-response curve. 4. Ouabain caused an increase in the time constant of decay of the ACh current, but the value in the presence of ouabain was not different from that of a lower concentration of ACh determined so as to give a response of the same peak amplitude. Therefore, the effect of ouabain is not on the process of receptor desensitization directly.     

Effects of α-bungarotoxin on acetylcholine-induced response at the Helix neuronal membrane

The effects of -bungarotoxin (-BT) on two patterns of acetylcholine (ACh)-induced response differing in desensitization rate were investigated in isolated mollusk neurons using intracellular dialysis and concentration clamping techniques. It was found that -BT depressed both types of ACh-induced response — a reversible action in the majority of experiments performed. It also exerted a blocking effect on ACh-induced currents dependent on the presence of albumin, although albumin itself produced no noticeable change in ACh-induced response. Concentration dependence of -BT-induced blockade on both types of currents evoked by 1 and 10 µM ACh was investigated. The -BT concentrations producing a 50% suppression of the current evoked by 1 µM ACh were calculated by approximating concentration plots as (13.85±1.25)×10^–9 and (5.56±1.0)×10^–8 g/ml for type A and B cells respectively.Institute of Experimental Biology. Academy of Sciences of the Armenian SSR, Erevan. Translated from Neirofiziologiya, Vol. 21, No. 6, pp. 729–735, November–December, 1989.     

Reversal of the Mitochondrial Phenotype and Slow Development of Oxidative Biomarkers of Aging in Long-lived Mclk1+/? Mice

Although there is a consensus that mitochondrial function is somehow linked to the aging process, the exact role played by mitochondria in this process remains unresolved. The discovery that reduced activity of the mitochondrial enzyme CLK-1/MCLK1 (also known as COQ7) extends lifespan in both Caenorhabditis elegans and mice has provided a genetic model to test mitochondrial theories of aging. We have recently shown that the mitochondria of young, long-lived, Mclk1^+/− mice are dysfunctional, exhibiting reduced energy metabolism and a substantial increase in oxidative stress. Here we demonstrate that this altered mitochondrial condition in young animals paradoxically results in an almost complete protection from the age-de pend ent loss of mitochondrial function as well as in a significant attenuation of the rate of development of oxidative biomarkers of aging. Moreover, we show that reduction in MCLK1 levels can also gradually prevent the deterioration of mitochondrial function and associated increase of global oxidative stress that is normally observed in Sod2^+/− mutants. We hypothesize that the mitochondrial dysfunction observed in young Mclk1^+/− mutants induces a physiological state that ultimately allows for their slow rate of aging. Thus, our study provides for a unique vertebrate model in which an initial alteration in a specific mitochondrial function is linked to long term beneficial effects on biomarkers of aging and, furthermore, provides for new evidence which indicates that mitochondrial oxidative stress is not causal to aging.Because it is well known that the aging process is characterized by declines in basal metabolic rate and in the general performance of energy-dependent processes, many aging studies have focused on mitochondria because of their central role in producing chemical energy (ATP) by oxidative phosphorylation (1). Among the various theories of aging that have been proposed, the mitochondrial oxidative stress theory of aging is the most widely acknowledged and studied (2–4). It is based on the observation that mitochondrial energy metabolism produces reactive oxygen species (ROS),² that mitochondrial components are damaged by ROS, that mitochondrial function is progressively lost during aging, and that the progressive accumulation of global oxidative damage is strongly correlated with the aged phenotype. However, the crucial question of whether these facts mean that mitochondrial dysfunction and the related ROS production cause aging remains unproven (5–7). Furthermore, recent observations made in various species, including mammals, have begun to directly challenge this hypothesis, notably by relating oxidative stress to long (8) or increased (9) lifespans, by demonstrating that overexpression of the main antioxidant enzymes does not extend lifespan (10) as well as by showing that mitochondrial dysfunction could protect against age-related diseases (11).A direct and powerful approach to attempt to clarify this major question and to test the theory is to characterize the mitochondrial function of long-lived mutants (12). CLK-1/MCLK1 is an evolutionary conserved protein (13) and has been found to be located in the mitochondria of yeast (14), worms (15), and mice (16). The inactivation of the Caenorhabditis elegans gene clk-1 substantially increases lifespan (17). Moreover, the elimination of one functional allele of its murine orthologue also resulted in an extended longevity for Mclk1^+/− mice in three distinct genetic backgrounds (18). These findings have provided for an evolutionarily conserved pathways of animal aging that is affected by the function of a mitochondrial protein (19, 20). In mitochondria CLK1/MCLK1 acts as an hydroxylase and is implicated in the biosynthesis of ubiquinone (coenzyme Q or UQ), a lipid-like molecule primarily known as an electron carrier in the mitochondrial respiratory chain and as a membrane antioxidant but which is also associated with an increasing number of different aspects of cellular metabolism (20, 21). Taken together, these observations indicate that the long-lived Mclk1^+/− mouse is a model of choice for the understanding of the links between mitochondrial energy metabolism, oxidative stress, and the aging process in mammals.Previous analysis of Mclk1^+/− mice, which show the expected reduction of MCLK1 protein levels (22), have revealed that their tissues as well as their mitochondria contain normal levels of UQ at 3 months of age (23). Yet the same study also revealed a host of phenotypes induced by Mclk1 heterozygosity (see below). Thus, it appears that MCLK1 has an additional function that is unrelated to UQ biosynthesis but responsible for the phenotypes observed in young Mclk1^+/− mutants. This is consistent with several results from nematodes which also strongly suggest that CLK-1 has other functions (24, 25).In depth characterization of the phenotype of young Mclk1^+/− mutants has revealed that the reduction of MCLK1 levels in these animals profoundly alters their mitochondrial function despite the fact that UQ production is unaffected (23). In fact, we have shown that Mclk1 heterozygosity induces a severe impairment of mitochondrial energy metabolism as revealed by a reduction in the rates of mitochondrial electron transport and oxygen consumption as well as in ATP synthesis and ATP levels in both the mitochondria and the whole cell. ATP levels in several organs were surprisingly strongly affected with, for example, a 50% reduction of overall cellular ATP levels in the livers of Mclk1^+/− mutants (23). Moreover, we have found that the Mclk1^+/− mice sustain high mitochondrial oxidative stress by a variety of measurements, including aconitase activity, protein carbonylation, and ROS production (23). Additionally, we have shown that this early mitochondrial dysfunction is associated with a reduction in some aspects of cytosolic oxidative damage and global oxidative stress that can be measured via recognized plasma biomarkers such as 8-isoprostanes and 8-hydroxy-2-deoxyguanosine (8-OHdG). Considering that the accumulation of global oxidative damage is known to be tightly linked to the aging process (26), this latter result suggests that the anti-aging effect triggered by low MCLK1 levels might already act at a young age.To further investigate the clk-1/Mclk1-dependent mechanism of aging as well as to try to elucidate the still unclear relation between mitochondrial dysfunction, oxidative stress, and aging, we have now carefully analyzed the evolution of the phenotype of Mclk1^+/− mutants over time. We have also studied the effects of reduced MCLK1 levels on the phenotype of mice heterozygous for the mitochondrial superoxide dismutase (Sod2), which represent a well known model of mitochondrial oxidative stress (27). In addition of confirming the long lifespan phenotype of the Mclk1^+/− mutants in a mixed background (129S6 x BALB/c), we also report here a study of mutants and controls on a completely isogenic background where we find that the condition of Mclk1^+/− mutants unexpectedly results in protection against the age-dependent loss of mitochondrial function. Moreover, we found that the mutants are characterized by a significant attenuation of the age-associated increase in global oxidative stress normally observed in mammals. We also show that the Mclk1^+/− condition can gradually reverse the deterioration of mitochondrial function and the associated increase of global oxidative stress that is normally observed in Sod2^+/− mutants. Thus, this study provides for a unique vertebrate model in which reduced levels of a specific mitochondrial protein causes early mitochondrial dysfunction but has long term beneficial effects that slow down the rate of aging, as established with appropriate biomarkers, and can ultimately prolong lifespan in mice. Furthermore, in line with recent studies that have raised doubts about the validity of the mitochondrial oxidative stress theory of aging (4, 8, 10), our results, which relate to a recognized long-lived mice model, represent a novel and crucial indication that mitochondrial oxidative stress might not by itself be causal to aging.     

Primary culture of lobster (Homarus americanus) olfactory sensory neurons

Lobster olfactory sensory neurons have contributed to a number of advances in our understanding of olfactory physiology. To facilitate further study of their function, we have developed conditions allowing primary culture of the olfactory sensory neurons in a defined medium. The most common cells in the culture were round cell bodies with diameters of 10-15 micro m that often extended fine processes, features resembling olfactory sensory neurons. We discovered that acetylcholinesterase acted as a growth factor for these cells, improving their survival in culture. We also confirmed previous evidence from spiny lobsters that poly-D-lysine was a superior substrate for olfactory cells of this size and morphology. We then identified olfactory sensory neurons in the culture in two ways. Almost half the cells tested responded to application of a complex odorant with an inward current. An even more rigorous test was made possible by the development of an antiserum to OET-07, an ionotropic glutamate receptor homolog specifically expressed by Homarus americanus olfactory sensory neurons. It labeled a majority of the round cells in the culture, unequivocally identifying them as olfactory sensory neurons.