beta-Actin is confined to structures having high capacity of remodelling in developing and adult rat cerebellum

Neurons undergo complex morphological changes during differentiation and in cases of plasticity. A major determinant of cell morphology is the actin cytoskeleton, which in neurons is comprised of two actin isoforms, non-muscle gamma- and beta-actin. To better understand their respective roles during differentiation and plasticity, their cellular and subcellular localization was examined in developing and adult cerebellar cortex. It was observed that gamma-actin is expressed at a constant level throughout development, while the level of beta-actin expression rapidly decreases with age. At the light microscopic level, gamma-actin staining is ubiquitous and the only developmental change observed is a relative reduction of its concentration in cell bodies and white matter. In contrast, beta-actin staining almost completely disappears from the cytoplasm of cell bodies, primary dendrites and axons. In young cerebellar cultures, gamma-actin is found in the cell body, neurites and growth cones, while beta-actin is mainly found in growth cones, as previously reported in other primary neuronal culture systems [Kaech et al. (1997), J. Neuroscience, 17, 9565-9572; Bassell et al., (1998), J. Neuroscience, 18, 251-265]. Electron microscopy of post-embedding immunogold-labelled tissue confirms the widespread distribution of gamma-actin, and also reveals an increased concentration of gamma-actin in dendritic spines in the adult. During development, beta-actin accumulation is observed in actively growing structures, e.g., growth cones, filopodia, cell bodies and axonal tracts. In the adult cerebellar cortex, beta-actin is preferentially found in dendritic spines, structures which are known to retain their capacity for morphological modifications in the adult brain. This differential subcellular localization and developmental regulation of the two actin isoforms point to their different roles in neurons.     

The correction of the immune and microcirculatory disorders in patients with chronic hepatitis of alcoholic and viral etiologies

A simple, rapid and sensitive method for the clean-up and analysis of cefoxitin in serum and tissue is described. Serum (0.5 ml) and tissue (100 mg) samples after homogenization underwent high speed centrifugation. Chromatography was performed on a muBondapak C18 cartridge using a mobile phase of 0.005 M potassium dihydrogen phosphate-acetonitrile-glacial acetic acid (77.5:22:0.5, v/v/v) with a flow-rate of 2.0 ml/min. Ultraviolet detection occurred at 235 nm. The procedure produced a linear curve for the concentration range 100-5000 ng/ml. The assay produced accurate, repeatable and rapid results for both tissue and serum samples without the need for chemical extraction.     

Blood supply of the Achilles tendon

The Escherichia coli low molecular mass penicillin-binding proteins are enzymes associated with the periplasmic face of the inner membrane. This mini review discusses the membrane anchoring of these enzymes and their possible participation in a putative membrane bound protein complex involved in the regulation of peptidoglycan biosynthesis. The identification of such a complex may lead to the identification of new sites of action for antibacterial compounds.     

Survivorship analysis of the Kinematic Stabilizer total knee replacement: a 10- to 14-year follow-up

The Kinematic Stabilizer is a posterior-cruciate-substituting design of total knee replacement. We have reviewed 109 primary total knee replacements in 95 patients at a mean follow-up time of 12.7 years (10 to 14). We used survival analysis with failure defined as revision of the implant. This gave a cumulative survival rate of 95% (95% CI +/- 5%) at ten years and (87% +/- 10%) at 13 years. These results from an independent centre confirm the value of an established design of cemented total knee replacement and question the wisdom of the introduction of modifications and new designs without properly controlled trials.     

Vitamin E as a universal antioxidant and stabilizer of biological membranes

The known literature data concerning the mechanisms of molecular action of vitamin E in biological membrane systems are reviewed. The role of vitamin E, possessing a broad range of biological activities, as a universal stabilizer of biological membranes in normal oxygen metabolism and peroxidation, and also in disorders of normal metabolism resulting in pathological alterations, has been discussed. The participation of vitamin E in redox reactions taking place in lipid media, its interaction with singlet oxygen, free fatty acids and enzyme systems are considered. Physiological effects of vitamin E and its ability to prevent numerous pathologies are also considered. Vitamin E was concluded to be a universal participant of antioxidant defence reactions in biological membranes, since it acts at all stages of membrane oxidative damage.     

Potentially reactive cyclic carbamate metabolite of the antiepileptic drug felbamate produced by human liver tissue in vitro

To gain insights into the different forms of modified amyloid beta peptides (A beta) in the Alzheimer disease (AD) and Down syndrome (DS) brain, we used two-site ELISAs with antibodies specific for isomerized (i.e. A beta with L-isoaspartate at positions 1 and 7) and pyroglutamate-modified (i.e. A beta beginning with pyroglutamate at position 3) forms of A beta to quantitate the levels of these different A beta peptides in formic acid extracts of AD and DS frontal cortex. Despite variations in the proportions of distinct forms of A beta in AD and DS frontal cortex, the major species of A beta in these samples were A betaN3(pyroGlu)-42 as well as A beta x-42 (where x is a residue at position 2 or less in A beta), whereas isomerized A beta was a minor species. Further, the levels of isomerized and pyroglutamate-modified forms of A beta terminating at amino acid 42 were higher than those ending at amino acid 40. The abundance of the distinct forms of A beta reported here in formic acid extracts of AD and DS frontal cortex suggests that these A beta species could play important roles in the deposition of A beta in AD and DS brains.