Impaired spare respiratory capacity in cortical synaptosomes from Sod2 null mice

Presynaptic nerve terminals require high levels of ATP for the maintenance of synaptic function. Failure of synaptic mitochondria to generate adequate ATP has been implicated as a causative event preceding the loss of synaptic networks in neurodegenerative disease. Endogenous oxidative stress has often been postulated as an etiological basis for this pathology, but has been difficult to test in vivo. Inactivation of the superoxide dismutase gene (Sod2) encoding the chief defense enzyme against mitochondrial superoxide radicals results in neonatal lethality. However, intervention with an SOD mimetic extends the life span of this model and uncovers a neurodegenerative phenotype providing a unique model for the examination of in vivo oxidative stress. We present here studies on synaptic termini isolated from the frontal cortex of Sod2 null mice demonstrating impaired bioenergetic function as a result of mitochondrial oxidative stress. Cortical synaptosomes from Sod2 null mice demonstrate a severe decline in mitochondrial spare respiratory capacity in response to physiological demand induced by mitochondrial respiratory chain uncoupling with FCCP or by plasma membrane depolarization induced by 4-aminopyridine treatment. However, Sod2 null animals compensate for impaired oxidative metabolism in part by the Pasteur effect allowing for normal neurotransmitter release at the synapse, setting up a potentially detrimental energetic paradigm. The results of this study demonstrate that high-throughput respirometry is a facile method for analyzing specific regions of the brain in transgenic models and can uncover bioenergetic deficits in subcellular regions due to endogenous oxidative stress.     

Dynamics of spermatogenesis in albino mice of different age groups

The age dynamics (beginning from the 2nd to the 455th days) of histomorphological indicators of testes in mongrel white mice in the process of postnatal development has been investigated. The age phases of spermatogenesis development in white mice and the transitional periods between them, which correspond to 6-15, 25-30, 175, 335 days are determined. An interrelation of spermatogenesis indicators during the postnatal development of white mice is described.     

Microbiocenosis of oral cavity in patients from different age groups

Worsening of state of oral cavity is observed not only in elderly persons, but also in adults aswell as in adolescents and children. The leading role in development of dental caries and periodontal diseases belongs to microorganisms. Oral cavity bacterial landscape was determined in adolescents, adults and elderly people with normal periodont or with gingivitis or periodontitis. The study showed that species and qualitative composition of oral cavity microflora were different in different age groups. In patients with normal periodont, non pathogenic (common commensals) microbial composition was revealed. In abnormal state of oral cavity, its microflora was characterized by the presence of high titers of potentiality pathogenic microorganisms.     

Fluidizing effects of centrophenoxine in vitro on brain and liver membranes from different age groups of mice

This study examined the effects of different concentrations of centrophenoxine on physical properties of synaptic plasma membranes and liver microsomes using electron spin resonance procedures. Membranes of different age groups of mice were labeled with the 5-doxyl stearic acid spin-label and membrane fluidity determined in the presence and absence of different concentrations of centrophenoxine. Centrophenoxine had a direct effect on membranes as shown by a significant increase in membrane fluidity. This effect was greatest in liver microsomes as compared to synaptic plasma membranes. Age differences were not observed in centrophenoxine-induced fluidization. Effects of centrophenoxine in vivo may be due in part to the drug acting directly on the physical properties of the membrane lipid environment.     

Kinetics ofd-aspartic acid release from rat cortical synaptosomes

A kinetic study has been made of the release ofd-aspartate from rat cortical synaptosomes following pre-loading with labelled D-aspartate, and the results compared to a previous study of the release of the acidic amino acids glutamate plus aspartate following pre-loading with labeledl-glutamate. Qualitatively, the results of the two studies are similar. The D-aspartate taken up during the preload period appears to be totally releasable. However, release is greatly increased by depolarizing media. The increased rate of release induced by increasing [K]_o is independent of the [Ca]_o, while veratrine-induced release is inhibited by [Ca]_o. Release is from more than a single compartment, since plots of the log₁₀ of the synaptosomal D-aspartate content (calculated from the label content) as a function of the incubation time are non-linear for all incubation solutions. In the previous study which utilizedl-glutamate pre-loading, the results were consistent with either a model consisting of two passive compartments (that is, synaptosomal content T as a function of time is given by Ae^–Kat+Be^–Kbt, in which A and B are compartment sizes, Ka and Kb are exchange constants, and t is incubation time) or a model consisting of one passive compartment (Ae^–Kat) and one saturated carrier compartment (T-Kbt, in which T=total content at zero time and Kb=maximal velocity). The present results withd-aspartate also give excellent fits to these models. However, there are some quantitative differences in the estimates of the compartment sizes and exchange constants, which are obtained by optimizing the fit of the data to the equation for each model. Although most of these quantitative differences appear to be minor, one difference between the two studies is of potential significance in interpretation of the results. In the glutamate study, all depolarizing media were found to reduce the exchange constant for the carrier mechanism, while in the present study, depolarizing media were found to increase the exchange constant, with the exception of veratrine-containing medium without calcium.     

Effect of indomethacin on selected immune parameters in different age groups of mice.

The authors studied the effect of indomethacin on the phagocytic activity of polymorphonuclear leucocytes (PMNL) and on haemolytic antibody formation (plaques) by lymphoid cells of the spleen in 3-, 6- and 12-month-old mice. In 3- and 12-month-old animals the phagocytic activity of the PMNL was significantly inhibited. Plaque formation was likewise significantly inhibited in 3-month-old mice, but it was significantly raised in 6- and 12-month-old animals.     

Influence of island geography,age and landscape on species composition in different animal groups

Aim To study the importance of ecological and geographical factors in explaining arthropod species composition on islands. Location The Aeolian Islands, a volcanic archipelago in the central Mediterranean, near Sicily. Methods The influence of island area, age, distance to the mainland, distance to the nearest island and land cover categories on species composition of arthropod groups was analysed using canonical correspondence analysis (CCA). The use of multiple animal groups in the same archipelago allowed the development of two complementary approaches based on CCA – a ‘taxon‐focused’ approach and an ‘island‐focused’ approach – to elucidate, respectively, how different taxa respond to the same environmental factors, and which factors are mainly responsible for the composition of the faunas in different locations. Results Island area was an important factor in explaining species composition in Chilopoda, Orthoptera and Tenebrionidae. Distance to the mainland was important mainly for Carabidae. Distance to the closest island was important for many groups. By contrast, island age exerted a significant influence only on the species composition of Orthoptera. Various groups were influenced by a combination of broad‐leaved forest and natural grassland. Main conclusions The example of the arthropods of the Aeolian Islands indicates that the influence of a given island characteristic on species composition varies among groups, although measures of inter‐island isolation were typically more important for taxa than isolation from the mainland source. This suggests that colonization of islands may occur mostly by stepping‐stone dispersal.     

Changes in lipid composition during protoplast isolation

During the isolation of mesophyll protoplast from leaves of Arabidopsis thaliana (L.) Heynh. the neutral lipids increased from 8% to 17% of the total lipids, while each of the polar lipids decreased by 10–20%. This treatment also induced acyl group migration which was indicated by the transfer of 16:3 from monogalactosyldiacyglycerol to other lipid. Similar results were obtained when leaf slices or vacuum infiltrated leaves were incubated in an aqueous solution containing 0.5 M sorbitol, indicating that the effect is not specifically related to cell wall removal. These observations suggest that the possible deleterious consequences of such lipid changes on the properties of membranes should be considered whenever protoplasts or protoplast-derived organelles are used for physiological studies.     

Tissue specificity of antioxidant system functioning and lipid peroxidation in different age groups of Amur carp

Key features of tissue enzymes functioning in antioxidant system (AOS) in sexually mature and immature individuals of Amur carp were studied. The activity of antioxidant enzymes was highest in the myocardium and subjected to age-related changes. It was concluded that changes in the functioning of AOS and intensity of lipid peroxidation processes are characterized by organ-tissue metabolic features and age peculiarities of metabolism that is most expressed in the myocardium.     

Changes in lipid composition of tritosomes during lysis

Membrane phospholipids and free fatty acids were analyzed after lysis of lysosomes which had engulfed Triton WR 1339 (tritosomes). Significant elevations of lysophosphatidyl choline and lysophosphatidyl ethanolamine were seen. Phosphatidyl choline, phosphatidyl ethanolamine and sphingomyelin decreased significantly. Triglyceride also fell. The released free fatty acids paralleled closely the liberation of β-glucuronidase from the tritosomes. Thus, lipases hydrolyzed endogenous phospholipids and neutral lipids of tritosomes during incubation at 37°C at pH 5.0 to produce significant elevations of lysophospholipids and free fatty acids. The known surface-active properties of these latter compounds raise the possibility of their participation in the process of lysis of the tritosomes.     

Changes in the lipid composition of Mucor hiemalis sporangiospores related to the age of the spore-forming culture

Analysis of sporangiospore lipids of the fungus Mucor hiemalis F-1156 showed that alterations occur in the content of fatty acids and individual classes of lipids during long-term cultivation (for about 20 days). The changes in the lipid composition related to the age of the spore-forming mycelium suggest an important role of sporangiospore lipids in spore germination and in further development of the spherical cells formed in this processes. The M. hiemalis F-1156 sporangiospores with a lipid pool exhausted during long-term cultivation can give rise to both mycelial and yeastlike growth.     

Changes of hormonal function of the adrenal and gonadal glands in baboons of different age groups

The purpose of this study was to characterize the changes of hormonal function of the adrenals and gonads during aging in male baboons ( Papio hamadryas ). Basal levels of plasma dehydroepiandrosterone, dehydroepiandrosterone sulfate, pregnenolone, and 17-hydroxypregnenolone progressively decrease with age from 10–15 years when analyzed by specific radioimmunoassay. However, no significant changes were found in cortisol and 11-desoxycortisol concentrations. The levels of sexual hormones did not differ in young and mature groups. In the 20–26-year-old animals, the concentration of testicular androgens showed a tendency to decrease, while the concentration of biologically active luteinizing hormone (LH) showed a tendency to increase. The old animals exhibited a decrease of plasticity of the pituitary–testicular system, which was manifested in the deceleration of the decrease of LH and T concentrations after the peak values had been reached in response to luteinizing hormone-releasing hormone (LHRH) administration. The oldest male also developed some refractoriness of the pituitary–gonadal system to the prolonged administration of LHRH agonist. The hormonal imbalance which develops with age may play an important role in the age-related involutional process.     

Changes in the lipid composition of blood serum in girls with different somatotypes after a meal

Changes in the neutral lipid and phospholipid composition of blood serum in response to meals were analyzed in girls with different somatotypes. After meals, a statistically significant decrease in the content of free fatty acids was observed in all subjects, irrespective of the somatotype. Statistically significant increases in the contents of readily oxidized phospholipid fractions were observed in girls of subathletic and athletic somatotypes. These data show the changes in the relationship between variable components of the lipid spectrum of lipoproteins. The main structural constituents of membrane lipoproteins, such as stable phospholipid fractions and free cholesterol, did not change in response to meals in girls of any somatotype. These data demonstrate a stability of membrane lipoprotein complexes in response to this physiological stimulus.     

Qualitative composition of the normal intestinal microflora in individuals from the various age groups

The study of the microflora of the large intestine in healthy adult volunteers of different age groups (25-36, 55-68 and 88-94 years old), living in Switzerland, has been carried out. As revealed by the analysis of the result obtained in this study, normal intestinal microflora in adults has different qualitative and quantitative characteristics at different periods of their life. The greatest diversity of intestinal microflora is observed at a mature age (55-68 years old), while the poorest microflora is observed in people more advanced in age. The amount of microorganisms inhabiting the intestine reaches its maximum in people of mature age and is low in elderly people. Changes in normal intestinal microflora are probaly linked with morpho-functional transformations in the host body at different periods of life. It is expedient to work out the criteria of norm for the microflora of different age groups with a view to use these criteria for the evaluation of the microbial status of the intestine in persons of different age.     

Changes in lipid composition of the maturing rat testis

1. The lipids and fatty acids of the lipids of testes of rats aged 4 weeks to 6 months were separated and analysed. 2. A decrease in concentration of triglyceride was noted, but there was no significant change in the concentration of phospholipids, plasmalogen or cholesterol during this time. 3. There were no significant differences in the total lipid concentration of palmitic acid, stearic acid, linoleic acid, arachidonic acid and docosatetraenoic acid between the various age groups. 4. A decrease in the concentration of oleic acid in the phosphatide and triglyceride fractions and an increase in the concentration of docosapentaenoic acid (characterized as the Delta4,7,10,13,16-isomer) in phosphatides but not in triglyceride were observed during the maturation period. 5. Histological studies indicated that the lipid changes occurred at the same time as the appearance and maturation of the spermatids.     

Presynaptic modulation by eicosanoids in cortical synaptosomes

In continuing experiments to determine the ionic basis of inhibitory presynaptic modulation, rat cortical synaptosomes were employed and receptor-activated K⁺ efflux was determined with a K⁺ sensitive electrode. When synaptosomes were sub-optimally depolarized by veratridine, the addition of agents that activated purinergic, ₂, muscarinic and opioid receptors all promoted K⁺ efflux. With 2-chloroadenosine as a model inhibitory presynaptic modulator, the increased K⁺ efflux evoked by this agent was blocked by the cyclooxygenase inhibitor indomethacin suggesting that arachidonic acid or its metabolites was an intermediary in opening the channel. When arachidonic acid and PGE₂ were tested, both promoted K⁺ efflux that was inhibited by dendrotoxin and mast cell degranulating peptide, two agents that are known to inhibit a delayed rectifier K⁺ current. Our results suggest that via eicosanoid second messengers, inhibitory presynaptic modulators open a sub-class of K channels that hyperpolarize nerve terminals, therefore less Ca²⁺ would enter per nerve impulse and thus the evoked release of neurotransmitters would be decreased.Abbreviations DTX dendrotoxin - MCDP mast cell degranulating peptide - NHGA norhydroguairetic acid - PGE₂ prostaglandin E₂     

Changes in muscle mitochondrial lipid composition resulting from training and exhaustive exercise.

This study was undertaken to determine if the changes in mitochondrial structure and function that occur in muscle with exhaustive exercise could be caused by alterations in lipid composition of mitochondrial membranes. Further, the effect of training on lipid composition was studied to ascertain if lipid changes accompany the adaptation in the level of mitochondrial protein. Training decreased free fatty acids and triglycerides. Exhaustion of untrained animals resulted in increases of total phospholipid and phosphatidyl choline while exhaustion of trained rats caused a lowering of total phospholipid and phosphatidyl choline. Alterations in membrane lipid composition are most likely not the cause of changes in mitochondrial structure and function after exhaustive exercise since mitochondrial yield and lipid levels did not change in concert; i.e. muscle mitochondrial yield was decreased in both untrained and trained rats while total phospholipids were increased in untrained rats and decreased in trained rats as a result of exhaustive exercise. Although the physiological significance of the effects observed remains to be determined, this study does demonstrate that the lipid composition of mitochondria is not a constant parameter but can change in response to a chronic (training) or acute (exhaustive exercise) physiological condition.     

Changes of bile lipid composition induced by methylprednisolone

Experiments were carried out on three groups of male guinea pigs to study the influence of methylprednisolone on the bile lipid composition. The cholesterol, phospholipid, and bile acids concentrations of the gallbladder bile in the control series were not significantly different from those of Group II, receiving SF for 45 days. In the methylprednisolone group, however, the absolute and relative molar concentrations of cholesterol increased while those of bile acids decreased compared to the former groups. Phospholipids on the other hand revealed only a relative increase. The observations indicate that use of methyl prednisolone for 45 days increases the lithogenicity of the bile in guinea pigs.