Rapid chromosome territory relocation by nuclear motor activity in response to serum removal in primary human fibroblasts

Background  

Radial chromosome positioning in interphase nuclei is nonrandom and can alter according to developmental, differentiation, proliferation, or disease status. However, it is not yet clear when and how chromosome repositioning is elicited.     

Quantitation of mitochondrial injury in cultured rat heart endothelioid cells with nitroblue tetrazolium

Synopsis A sensitive method is presented for measurement of changes in the permeability of mitchondria in cultured cells. Rat heart endothelioid cells were used to determine the penetration rate of nitroblue tetrazolium (NitroBT) or other reactants into mitochondriain situ. Nitroblue formazan, produced as a consequence of succinate dehydrogenase activity in the mitochondria, was eluted and measured with a spectrophotometer. Prior injury of cells with hypo-osmolar solutions increased the rate of formazan production. Several methods are described or suggested for the statistical analysis of the data.     

Superoxide dismutase is upregulated in <Emphasis Type="Italic">Staphylococcus aureus</Emphasis> following protoporphyrin-mediated photodynamic inactivation and does not directly influence the response to photodynamic treatment

Background  

Staphylococcus aureus, a major human pathogen causes a wide range of disease syndromes. The most dangerous are methicillin-resistant S. aureus (MRSA) strains, resistant not only to all β-lactam antibiotics but also to other antimicrobials. An alarming increase in antibiotic resistance spreading among pathogenic bacteria inclines to search for alternative therapeutic options, for which resistance can not be developed easily. Among others, photodynamic inactivation (PDI) of S. aureus is a promising option. Photodynamic inactivation is based on a concept that a non toxic chemical, called a photosensitizer upon excitation with light of an appropriate wavelength is activated. As a consequence singlet oxygen and other reactive oxygen species (e.g. superoxide anion) are produced, which are responsible for the cytotoxic effect towards bacterial cells. As strain-dependence in photodynamic inactivation of S. aureus was observed, determination of the molecular marker(s) underlying the mechanism of the bacterial response to PDI treatment would be of great clinical importance. We examined the role of superoxide dismutases (Sod) in photodynamic inactivation of S. aureus as enzymes responsible for oxidative stress resistance.     

Modelling ultraviolet exposures in a school environment.

A technique has been developed to represent erythemally effective ultraviolet radiation exposure within a school environment. The technique models the erythemally effective exposure onto a horizontal plane representation of a mapped school environment located in Hervey Bay (25 degrees S, 153 degrees E), Australia. The input parameters used to model the ultraviolet exposures received within the school playground included the measured sky view, ground albedo and standing surface albedo. Estimates of the erythemally effective ultraviolet exposure received within the school playground during morning tea and lunch time meal breaks during a winter and summer school day are presented. The influence of tree shade and building structure was found to vary significantly with solar zenith angle modelled over the winter and summer school meal break times with horizontal plane exposures predicted to vary from between 0 and 7 SED at different locations within the playground. The technique presented provides a method that can be followed to examine the effect of surrounding buildings and surface structures of real environments on the predicted horizontal plane ultraviolet exposure.     

Chondroitin sulphate at the endothelial lumen of pig aorta: Assay by radiolabelling and by X-ray microanalysis

Trypsin-releasable glycosaminoglycans from the luminal surface of intact pig aorta were measured following metabolic labelling with³⁵S]sulphate. Chondroitin sulphate was found to be present at a surface density equal to that already established for heparan sulphate (5×10¹¹ chains per cm²). This result was confirmed by X-ray microanalysis of the luminal sulphur content before and after treatment with specific glycosaminoglycan-degrading enzymes. This result implies that approximately half of the luminal surface is occupied by sulphated glycosaminoglycans.     

Turnover of Brain Monoamine Oxidase Measured In Vivo by Positron Emission Tomography Using l-[11C]Deprenyl

The distribution of carbon-11-labeled L-deprenyl, an irreversible inhibitor of monoamine oxidase type B (MAO-B), was determined in the baboon brain by positron emission tomography. The irreversible blood-to-brain transfer constant (influx constant, K_i) was measured using a complete metabolite-corrected arterial plasma concentration curve. This influx constant was used as a measure of functional enzyme activity for sequential determinations of MAO-B recovery following a single high dose of unlabeled l -deprenyl. The half-life for turnover of MAO-B was thus determined to be 30 days. Using appropriate irreversible inhibitors, this procedure should be generally useful for determining enzyme turnover rates in any organ in vivo and can be applied to some human studies as well.     

Polysaccharide production in liquid cell suspension cultures of Phleum pratense L.

The production of carbohydrates by cell suspension cultures of Phleum pratense (timothy grass) is described. Extracellular polysaccharides similar in monosaccharide composition to native cell wall polymers were accumulated, together with polymers of fructose (fructans). The fructans had similar properties to the intracellular reserve polymers found in intact plants, and were found in both cells and media of young, slow-growing cultures.Production of extracellular polysaccharides differed in cultures grown on sucrose or equimolar glucose/fructose as carbon source. These differences were observed only when autoclaved media were used, and were not related to changes in either pH or osmolarity. Autoclaving medium containing radioactive glucose and fructose produced a novel, unidentified labelled compound which was absent in medium containing labelled sucrose.