NMDA excitotoxicity and free radical generation in rat brain homogenates: Application of a chemiluminescence assay

NMDA, the specific agonist of glutamate gated ion channels permeable to calcium, is implicated as a causal factor in the pathogenesis of several neurobiological disorders such as stroke, seizures, ischemia, and chronic neurodegenerative disease. On the other hand, evidence on the roles of oxidative mechanisms involved in NMDA-induced neurotoxicity is accumulating. In this study, we have used chemiluminescence measurements as an easy, rapid and sensitive assay to investigate the effects of NMDA and oxidative stress on brain cell vulnerability. Rat brain homogenates were incubated with increasing concentrations of glutamate and NMDA. Production of reactive oxygen species was followed by single photon emission measurements using the specific enhancers luminol and lucigenin. Increases in emission were observed at excitotoxic concentrations of glutamate and NMDA. Other parameters of oxidative stress such as diene conjugates, TBARS and carbonyl groups were also investigated. Our results indicated that chemiluminescence measurements may be used to study involvement of oxidative stress in neurotoxicity.     

Changes in malondialdehyde content and in superoxide dismutase, catalase and glutathione reductase activities in sunflower seeds as related to deterioration during accelerated aging

Sunflower ( Helianthus annuus L.) seeds progressively lost their ability to germinate at 25°C, the optimal temperature for germination, after accelerated aging was carried out at 45°C (a temperature too high to permit germination) in water or at 76 or 100% relative humidity (RH). The deleterious effects of the high-temperature treatment increased with increasing seed moisture content. Incubation of seeds at 45°C in water resulted in electrolyte leakage, which indicated a loss of membrane integrity. A relationship between leakage and loss of seed viability could not be assumed, since no increase in electrolyte efflux occurred after aging al 100% RH. Accelerated aging induced accumulation of malondialdehyde, suggesting that seed deterioration was associated with lipid peroxidation. However, there was no direct relationship between lipid peroxidation and deterioration in membrane integrity. Loss of seed viability was also associated with a decrease in superoxide dismutase, catalase and glutathione reductase activities. Finally, the results obtained suggest that sunflower seed deterioration during accelerated aging is closely related to a decrease in the activities of detoxifying enzymes and to lipid peroxidation.     

Sexual behavior of donkey jacks: influence of ejaculatory frequency and season

The courtship of 5 jacks was evaluated weekly for 12 mo. The characteristics of sexual behavior were recorded before the collection of 2 ejaculates, at 4-h intervals, into an artificial vagina in the presence of a female in either natural or induced estrus. The maximum time given to the jack to perform the ejaculatory mount was 1 h. If the jacks did not ejaculate, another attempt was made the following week. At the time of collection, the male and female remained free in a paddock (20 m2). The data presented in this study is based on results in which the first and second ejaculates occurred successively. Statistical analysis was done by a 2 x 2 factorial design in randomized blocks. The mean +/- SEM of sexual behavior characteristics for the first and second ejaculate were, respectively: time until first mount = 0.7 +/- 0.2 and 0.9 +/- 0.2 min; time until first erection = 11.9 +/- 1.1 and 11.6 +/- 1.1 min; time until ejaculation = 15.0 +/- 1.2 and 13.6 +/- 1.2 min; frequency of partial exposure of penis = 3.4 +/- 0.4 and 3.2 +/- 0.4; frequency of total exposure of penis = 1.0 + 0.2 and 1.1 +/- 0.2; frequency of flehmen responses = 6.6 +/- 0.5 and 4.6 +/-0.5; frequency of erections = 1.3 +/- 0.1 and 1.2 +/- 0.1; frequency of retreats away from the female = 1.8 +/- 0.2 and 1.0 +/- 0.2; frequency of mounts with erection but without ejaculation = 0.3 +/- 0.1 and 0.1 +/- 0.1; frequency of mounts without erection = 2.0 +/-0.1 and 1.2 +/- 0.1 ; and frequency of pelvic copulatory movements = 4.8 +/- 0.4 and 4.4 +/- 0.4. Individual differences were observed (P<0.05) for partial and total exposure, flehmen responses, mounts without erection and pelvic copulatory movements. The variables flehmen responses, retreats away from the female and mounts without erection showed significant differences (P<0.05) between ejaculates. Seasonal effects on sexual behavior characteristics were not found. However, a monthly effect was noted for flehmen responses, partial exposure of the penis, mounts without erection, retreats away from the female and pelvic copulatory movements when the 2 ejaculates were combined.     

Effect of oxygen supply on metabolism of immobilized and suspended Escherichia coli

The effect of reduced oxygen supply on the production of a recombinant protein (plasmid-encoded beta-galactosidase) was investigated in Escherichia coli. A novel modified bubble tank reactor was used to provide a direct comparison between immobilized and suspended cells in identical environments except for the immobilization matrix. Decreased oxygen supply led to increased beta-galactosidase synthesis by both immobilized and suspended cells. Immobilized cells produced similar amounts of beta-galactosidase as the suspended cells. Lactose consumption and acetate production, on a per cell basis, were significantly higher in immobilized cells, suggesting that immobilized cells utilized fermentative metabolism. However, a transport analysis of the immobilized cell system showed that immobilized cells were not subject to either external or internal mass transfer gradients.     

Advantages of the scanning ion microscopy for mapping halogen corticoids in normal and transformed cells in culture

Summary— The intra-cellular distribution of eight halogen glucocorticoids was investigated by ion microscopy in two cellular varieties of cultured non-cancer cells (fibroblast 3T3) and cancer cells (human breast tumor cells MCF-7). Two types of ion microscopy helped to determine this distribution, a direct imaging ion microscope (SMI 300) with low spatial resolution, and a scanning ion microscope (IMS4F), featuring high resolution, serving to obtain maps representing the intra-cellular distribution of the fluorine elements and drugs present in these monolayer cultured cells. The fluorine images representative of the drugs containing fluorine showed that these drugs are essentially concentrated in the cell nuclei. In these nuclei, the distribution of these drugs is different from that of heterochromatin and of the nucleolus.     

Dynamics of colony development in the paper waspPolistes dominulus Christ (Hymenoptera,Vespidae): The influence of prey availability

This study focused on how a decrease in prey availability affected the development of aP. dominulus Christ colony. Nutritional oophagy and larval development were parameters found to be most directly affected. The more indirect effects on the growth of the nest and on offspring production were also analyzed.     

Dystrophin (Xp21), a New Phenotype Marker of Cultured Rat Aortic Myocytes

Dystropbin is a low-abundance cytoskeletal protein involved in the maintenance of membrane integrity in striated muscle. Very little is known about its role in smooth muscle. Utrophin (a dystropbin-related protein) is an ubiquitous protein whose role is still unclear. Changes in the expression of both proteins (if any) during phenotypic modulation of smooth muscle have not yet been reported. In contrast, modulated expression of heavy-molecular-weight caldesmon (h-CaD), a well-known specific regulatory protein of the contractile apparatus in smooth muscle, is well documented, along with its nonmuscle isoform, low-molecular-weight caldesmon (l-CaD), and other cytoskeletal proteins. We investigated three properties of cultured rat aortic smooth muscle cells: morphology, contractile ability, and expression of dystrophin, utrophin, h-CaD, and l-CaD. Cells were grown either in serum substitute supplemented medium (U-medium), where they reexpressed contractility, or in fetal calf serum-supplemented medium (F-medium), where they did not. It was found that only cultures grown in U-medium continued expressing dystrophin, even during the proliferation phase, contrary to cells grown in F-medium. However, when F-medium was changed for U-medium the cells recovered their contractility and reexpressed dystrophin. Expression of utrophin, h-CaD, and l-CaD was similar in both culture types. Dystrophin was demonstrated to be a true phenotype marker of cultured rat aortic smooth muscle cells, particularly with respect to their actual contractility.     

Regulation of μ-Opioid Receptor mRNA in Rat Globus Pallidus: Effects of Enkephalin Increases Induced by Short- and Long-Term Haloperidol Administration

Abstract: The mRNA encoding μ-opioid receptors is expressed in neurons of the globus pallidus, a region of the basal ganglia that receives a dense enkephalinergic innervation from the striatum. The regulation of the mRNAs encoding the opioid peptide enkephalin in the striatum and the μ-opioid receptor in the globus pallidus was examined with in situ hybridization histochemistry following short- or long-term haloperidol treatments, which alter striatal enkephalin mRNA levels. Animals were administered haloperidol daily for 3 or 7 days (1 mg/kg, s.c.) or continuously for 8 months (1 mg/kg, depot followed by oral). Enkephalin and μ-opioid receptor mRNA levels were unchanged after 3 days of haloperidol treatment. In contrast, the enkephalin mRNA level was increased in the striatum, and μ-opioid receptor mRNA levels were markedly decreased in the globus pallidus after 7 days of haloperidol administration. Similar effects were observed in rats treated with haloperidol for 8 months. The results provide the first evidence of regulation of μ-opioid receptor mRNA in vivo.