Sulphate reduction and methane oxidation rates of Håkon Mosby mud volcano sediments measured at station MSM16/2_847-1 (Z2-S2, aged flow surface)

Sulfate reduction (SR) and anaerobic oxidation of methane (AOM) were measured ex situ by the whole core injection method (doi:10.1080/01490457809377722). We incubated the samples at in situ temperature (1.0°C) for 12 hours with either 14** CH4 (dissolved in water, 2.5 kBq) or carrier-free 35** SO4 (dissolved in water, 50 kBq). Sediment was fixed in 25 ml 2.5% sodium hydroxide (NaOH) solution or 20 ml 20% ZnAc solution for AOM or SR, respectively. Turnover rates were measured as previously described (http://edoc.mpg.de/177065; doi:10.4319/lom.2004.2.171).

Communication peculiarities of early-aged children from speech risk group with close grownups

More children with different versions of speech disorders appear in Russia last decades. This situation reflects general tendency of national health deterioration. Our practical experience shows that close grownups can?t communicate to children with limited health capacity. As a result there arise social disabilities in child development. Speech communication is one of the forms of global communicative interaction process between close grownups and young child in the course of which there is a redistribution of knowledge and ignorance (Nikas Luman,2005). Within a framework of sociocultiral theory of mental growth we consider the appearance of speech communication under any cases of physical illness is possible only under conditions of correctly- organized communication between grownups and young children. (L.S. Vigotski ,2000). The special value in this aspect acquires the study of communication between grownups and young children. For five years we have been conducting the surveys on the problem of communicative contacts between parents and non-verbal children. Analysis of received data gave us the opportunity to systematize peculiar communicative interaction of adults and children who have some lapses in acquiring speech form communication. We have revealed four versions of situational- business communication between close grownups and young children with disabilities in acquiring speech. We have assumed that four versions of situational- business communication negatively affect speech form communication formation.

Aurintricarboxylic acid prevents GLUR2 mRNA down-regulation and delayed neurodegeneration in hippocampal CA1 neurons of gerbil after global ischemia

Aurintricarboxylic acid (ATA), an inhibitor of endonuclease activity and other protein–nucleic acid interactions, blocks apoptosis in several cell types and prevents delayed death of hippocampal pyramidal CA1 neurons induced by transient global ischemia. Global ischemia in rats and gerbils induces down-regulation of GluR2 mRNA and increased α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-induced Ca2+ influx in CA1 before neurodegeneration. This result and neuroprotection by antagonists of AMPA receptors suggests that formation of AMPA receptors lacking GluR2, and therefore Ca2+ permeable, leads to excessive Ca2+ influx in response to endogenous glutamate; the resulting delayed neuronal death in CA1 exhibits many characteristics of apoptosis. In this study, we examined the effects of ATA on expression of mRNAs encoding glutamate receptor subunits in gerbil hippocampus after global ischemia. Administration of ATA by injection into the right cerebral ventricle 1 h before (but not 6 h after) bilateral carotid occlusion prevented the ischemia-induced decrease in GluR2 mRNA expression and the delayed neurodegeneration. These findings suggest that ATA is neuroprotective in ischemia by blocking the transcriptional changes leading to down-regulation of GluR2, rather than by simply blocking endonucleases, which presumably act later after Ca2+ influx initiates apoptosis. Maintaining formation of Ca2+ impermeable, GluR2 containing AMPA receptors could prevent delayed death of CA1 neurons after transient global ischemia, and block of GluR2 down-regulation may provide a further strategy for neuroprotection.

Neurosteroids: Deficient cognitive performance in aged rats depends on low pregnenolone sulfate levels in the hippocampus

Pregnenolone sulfate (PREG S) is synthesized in the nervous system and is a major neurosteroid in the rat brain. Its concentrations were measured in the hippocampus and other brain areas of single adult and aged (22–24 month-old) male Sprague–Dawley rats. Significantly lower levels were found in aged rats, although the values were widely scattered and reached, in about half the animals, the same range as those of young ones. The spatial memory performances of aged rats were investigated in two different spatial memory tasks, the Morris water maze and Y-maze. Performances in both tests were significantly correlated and, accompanied by appropriate controls, likely evaluated genuine memory function. Importantly, individual hippocampal PREG S and distance to reach the platform in the water maze were linked by a significant correlation, i.e., those rats with lower memory deficit had the highest PREG S levels, whereas no relationship was found with the PREG S content in other brain areas (amygdala, prefrontal cortex, parietal cortex, striatum). Moreover, the memory deficit of cognitively impaired aged rats was transiently corrected after either intraperitoneal or bilateral intrahippocampal injection of PREG S. PREG S is both a γ-aminobutyric acid antagonist and a positive allosteric modulator at the N-methyl-d-aspartate receptor, and may reinforce neurotransmitter system(s) that decline with age. Indeed, intracerebroventricular injection of PREG S was shown to stimulate acetylcholine release in the adult rat hippocampus. In conclusion, it is proposed that the hippocampal content of PREG S plays a physiological role in preserving and/or enhancing cognitive abilities in old animals, possibly via an interaction with central cholinergic systems. Thus, neurosteroids should be further studied in the context of prevention and/or treatment of age-related memory disorders.

Spatial memory is related to hippocampal subcellular concentrations of calcium-dependent protein kinase C isoforms in young and aged rats

Relationships were examined between spatial learning and hippocampal concentrations of the α, β2, and γ isoforms of protein kinase C (PKC), an enzyme implicated in neuronal plasticity and memory formation. Concentrations of PKC were determined for individual 6-month-old (n = 13) and 24-month-old (n = 27) male Long–Evans rats trained in the water maze on a standard place-learning task and a transfer task designed for rapid acquisition. The results showed significant relationships between spatial learning and the amount of PKC among individual subjects, and those relationships differed according to age, isoform, and subcellular fraction. Among 6-month-old rats, those with the best spatial memory were those with the highest concentrations of PKCγ in the particulate fraction and of PKCβ2 in the soluble fraction. Aged rats had increased hippocampal PKCγ concentrations in both subcellular fractions in comparison with young rats, and memory impairment was correlated with higher PKCγ concentrations in the soluble fraction. No age difference or correlations with behavior were found for concentrations of PKCγ in a comparison structure, the neostriatum, or for PKCα in the hippocampus. Relationships between spatial learning and hippocampal concentrations of calcium-dependent PKC are isoform-specific. Moreover, age-related spatial memory impairment is associated with altered subcellular concentrations of PKCγ and may be indicative of deficient signal transduction and neuronal plasticity in the hippocampal formation.