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.     

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.     

Influence of atropine and carbachol on the fluorescence of catecholaminergic structures in selected areas of the rat brain.

Using the formaldehyde-fluorescence technique, the authors studied the influence of atropine and carbachol, administered intraventricularly to Wistar rats, on the fluorescence of catecholaminergic structures in 20 areas of the CNS, situated within the range of the 10th-46th frontal plane according to KONIG and KLIPPEL. 1. A confirmation of the antagonistic action of atropine and carbachol was obtained. It was expressed by mutually opposed occurrence of the specific fluorescence of the catecholaminergic structures. 2. In 16 out of 20 studied areas of the CNS, carbachol abolished or considerably weakened the specific fluorescence. In 3 areas it was increased by this drug, and one area proved insensitive. 3. Atropine increased the specific fluorescence in the DA (dopaminergic system) areas, while it had varying effects in the NA (noradrenergic system areas. In some areas of the CNS it increased and in others reduced the specific fluorescence of the catecholaminergic structures. 4. An interference between atropine and carbachol is observed, but it seems that the results of the present experiment speak in favour of an interaction between the catecholamine transmitters and ACh in the particular areas of the CNS under the influence of atropine and carbachol. 5. The authors discuss in detail the reactions of the catecholaminergic structures in the particular areas of the CNS, in which, as compared with the control, an increase or a decrease of the specific fluorescence under the influence of the administered drugs was observed.     

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.     

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.     

Basal autophosphorylation of insulin receptor occurs preferentially on the receptor conformation exhibiting high affinity for insulin and stabilizes this conformation

Insulin signal transmission through the plasma membrane was studied in terms of relationship between basal autophosphorylation of the β-subunit and the ability by bind insulin by the -subunit of the insulin receptor. In a cell free system, receptors phosphorylated on tyrosine residues in the absence of insulin were separated from non-phosphorylated receptors using antiphosphotyrosine antibodies. Insulin binding assays were then performed on basally autophosphorylated and on non-phosphorylated receptors. We found that the tyrosine phosphorylated receptors, which corresponded to 25% of the total number of receptors, were accountable for 60–80% of insulin binding. Scatchard representation of binding data has shown that the plot corresponding to tyrosine phosphorylated receptors was localized above, and was steeper than the plot corresponding to non-phosphorylated receptors. These data make it likely that the conformation of -subunit which favours ligand binding is connected to the conformation of β-subunit which favours phosphate reception on tyrosine residues. Reciprocally, the high-affinity conformation of insulin receptor seems to become stabilized by basal autophosphorylation.     

The use of automated image analysis for rapid measurement of the in vitro attachment of Candida albicans to transparent acrylic

A rapid method for measuring the in vitro attachment of Candida albicans to the surface of transparent acrylic is described. The method involves use of the 'Magiscan' automated image analysis system which measures attachment in terms of percentage area coverage. These measurements correlate highly significantly ( P < 0·001) with the number of adherent yeast cells.     

Prevalence of the 281 (Gly→Glu) mutation in hepatoerythropoietic porphyria and porphyria cutanea tarda

Summary The prevalence of the 281 (GlyGlu) mutation in hepatoerythropoietic porphyria (HEP) was investigated by the use of hybridization with a synthetic oligonucleotide probe. The mutation was found in HEP-affected members of two unrelated families from Spain, but was absent in two other patients from Italy and Portugal who also had HEP. Moreover, this mutation was not detected in 13 unrelated cases of familial (type II) porphyria cutanea tarda.