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.     

Elastase in the different primary granules of the human neutrophil

Elastase in the human neutrophil is associated with various subpopulations of primary granules of different density. The proportion of this enzyme that is extracted with acetate pH 4.2 and cetyltrimethylammonium bromide varies in the different subpopulations. Nevertheless, the electrophoretic mobility and relative proportions of elastase isoenzymes is the same in both extracts from the different subpopulations. On stimulation of neutrophils with N-formylmethionylleucylphenylalanine, elastase is not released from the least dense subpopulation, whereas other two subpopulations do undergo degranulation to approximately the same extent. However, the release of elastase from these two denser granules differs after they are isolated and treated with calcium.     

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.     

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.     

Vasomotor control: functional hyperemia and beyond

Historically, functional hyperemia has been viewed largely as an interaction between a parenchymal cell and its associated microvasculature. Locally released metabolites have been thought to produce relaxation of the smooth muscle and a vasodilation that increases blood flow in proportion to metabolic need. This symposium report presents evidence from a variety of disciplines and a number of different types of biological preparations that demonstrates that functional hyperemia is a complex process involving several classes of microvessels including capillaries, arterioles, and small arteries. These vessels do not function independently but are coordinated by a complex set of interrelations involving at least three different modes of interaction between parenchymal cells and the various segments of the vascular bed. These are local metabolic effects, propagated effects extending over long segments of the vasculature, and flow-dependent vasodilation induced by local changes in blood flow. In addition to these acute responses to metabolic demand it appears that tissues may be capable of more long-term structural alterations of the arterial and arteriolar network in response to sustained changes in the relationship between supply and demand. The vascular bed appears to be able to adapt either by increasing the maximal anatomic diameter of the large arteries or by inserting new arterioles into the parenchyma. Thus, classical functional hyperemia appears to be but one manifestation of a multifaceted process leading to highly coordinated responses of many vascular elements, resulting finally in vascular patterns that are optimized to meet parenchymal cell demands.     

Interleukin 1 stimulates endothelial cells to release multilineage human colony-stimulating activity

Cultured human umbilical vein endothelial cells, when exposed to soluble products of peripheral blood monocytes, elaborate granulocyte-macrophage colony-stimulating activity (GM-CSA) and erythroid burst-promoting activity (BPA). We have performed studies to determine if the monokine IL 1 can stimulate endothelial cells to release hematopoietic growth factors and whether such factors can also support human megakaryocyte (Meg) and mixed-cell colony growth. Various concentrations of recombinant human IL 1 beta (rIL 1) and media conditioned by monocytes (MCM), endothelial cells (ECM), and endothelial cells cultured for 3 days in 50% MCM (ECMM) or rIL 1 (ECMrIL 1) were added to marrow mononuclear cells cultured in methylcellulose. ECMM and ECMrIL 1 stimulated, in a dose-dependent fashion, the growth of Meg, mixed-cell, and GM colonies and erythroid bursts. In contrast, ECM, MCM, and rIL 1 displayed little or no activity in the colony-forming assays. Preincubation with specific antisera to native human IL 1 or rIL 1 reduced by 75 to 100% the activity of MCM in stimulating endothelial cell release of BPA, GM-CSA, Meg-CSA, and mixed-cell CSA. Meg-CSA, although readily detectable at ECMM and ECMrIL 1 concentrations in culture of 1 to 5%, was partially masked by lineage-specific inhibitors of Meg colony growth. When ECMM was analyzed by gel filtration chromatography, the megakaryocytopoietic inhibitory activity eluted in the high Mr fractions (greater than 75 kD). Meg-CSA co-eluted with GM-CSA and BPA in a single peak of 30 kD. We conclude that endothelial cells, in response to IL 1, produce one or more growth factors that probably act on multiple classes of progenitor cells.     

The isolation and characterization of 2-carboxyethyl adducts following in vitro reaction of acrylic acid with calf thymus DNA and bioassay of acrylic acid in female Hsd:(ICR)Br mice

Reaction of acrylic acid (AA) at pH 7.0 and 37 degrees C for 40 days with 2'-deoxyadenosine (dAdo), 2'-deoxycytidine (dCyd), 2'-deoxyguanosine (dGuo) and thymidine (dThd) resulted in the formation of 2-carboxyethyl (CE) adducts via Michael addition. The alkylated 2'-deoxynucleoside adducts isolated (percent yield after 40 days) were 1-CE-dAdo (5%), N6-CE-dAdo (11%) (via Dimroth rearrangement of 1-CE-dAdo), 3-CE-dCyd (7.5%), 7-CE-Gua (4%), 7,9-bis-CE-Gua (0.9%) (formed by reaction of AA with depurinated 7-CE-Gua during the course of the reaction) and 3-CE-dThd (0.5%). The products isolated following in vitro reaction of AA with calf thymus DNA at pH 7.0 and 37 degrees C for 40 days were (nmol/mg DNA) 1-CE-Ade (9.9), N6-CE-Ade (8.2), 7-CE-Gua (7.2) and 3-CE-Thy (1.9). Compound 3-CE-Cyt was not detected. Thus the adducts formed following in vitro reaction of AA with DNA are identical to those formed by in vitro reaction of the carcinogen beta-propiolactone (BPL) with DNA as reported in an earlier paper. Structures were assigned on the basis of identical UV spectra, Rf values on paper chromatograms and Rt values on HPLC as marker compounds prepared from reactions of BPL with 2'-deoxynucleosides and 2'-deoxynucleotides-5'-monophosphoric acids. AA was assayed for carcinogenic activity by s.c. injection (20 mumol, once a week for 52 weeks) in female Hsd: (ICR)Br mice. Two mice with sarcomas at the site of application were observed out of 30 mice. Malignancies were not observed in solvent and no-treatment controls. The bioassay results reported in this paper and elsewhere in the same strain of mice suggest that AA is a weak carcinogen in female Hsd:(ICR)Br mice.