SCE frequencies in lymphocytes of systemic lupus erythematosus patients

The frequency of sister-chromatid exchanges (SCEs) was investigated in peripheral lymphocytes of lupus erythematosus patients and compared with values obtained for healthy controls. Irrespective of the kind of medical treatment, an increased level of spontaneously occurring SCEs could be demonstrated in lupus patients. In addition to spontaneously occurring SCEs, mitomycin C (MMC)-induced SCEs were evaluated. No difference between patients and controls was found with respect to MMC-induced SCEs.     

Apatite-forming ability of alumina and zirconia ceramics in a supersaturated Ca/P solution

The apatite-forming ability of alumina and zirconia ceramics was investigated using a supersaturated Ca/P solution. After 2h of immersion, a thin, needle-like nanocrystalline layer with micron-sized clusters of an irregular shape was formed on the alumina and zirconia surfaces. With a longer immersion time the layer thickness increased and the clusters became more spherical. The substrate material has little or no effect on the forming ability of the coating. The XPS Ca/P ratio for the sputtered coating on the zirconia substrate that was immersed in the Ca/P solution for 27 h was 1.66. The EDS, XRD and XPS analyses confirmed that the coated layer was hydroxyapatite. The thickness of the hydroxyapatite coating on the zirconia and alumina substrates after immersion in the Ca/P solution for 8 and 27 h was from 0.8 to 1.1 microm.     

A case of canine hypodontia in an early Croatian cemetery Strance-Gorica

In the old Croatian cemetery Strance-Gorica in the Vinodol region, dating from the 9th to 11th century, osteological parts of the upper and the lower jaws with teeth were found, besides some other archeological finds. Data processing in dentistry regarding a possible presence of hypodontia was carried out on archeological finds (skeletal remains) on 27 persons available for the research. Only one case of canine hypodontia was found and described. In the remaining 26 persons no case of hypodontia was found on the relicts of the upper and lower jaws nor in other teeth groups. The frequency of hypodontia in the old Croatian cemetery Strance-Gorica was 3.7, which corresponds to the frequency of this anomaly in the 20th century population of Croatia.     

Effect of food quality on the body temperature of wasps (Paravespula vulgaris)

Body surface temperature of individually marked wasps (Paravespula vulgaris, Vespidae, Hymenoptera) was measured by infrared thermography during repeated visits to a feeding bowl without injuring them or disturbing their behavior. Wasps were fed 0.5, 1 and 2 mol/l sucrose solution at two ambient temperatures.Thoracic temperature varied significantly in dependence on food quality (sucrose concentration of solution). At the higher ambient temperatures of 26.1-30.2 degrees C mean thoracic surface temperatures from different experiments were 35.3 and 38.0 degrees C when the wasps took a 0.5 mol/l sucrose solution, 37.0, 38.7 and 38.7 degrees C when they took a 1 mol/l solution, and 39.1 degrees C when they took a 2 mol/l sucrose solution. At the lower ambient temperatures of 17.6-21.0 degrees C thoracic temperatures were lower but the effect of different sucrose concentrations was similar: 34.7 degrees C with a 0.5 mol/l and 36.1 degrees C with a 1 mol/l sucrose solution. The concentration effect amounted to about 10-25% of the whole variability of thorax temperature. By contrast, the temperatures of the head and abdomen did not follow the changes in thorax temperature according to changes in sucrose concentration closely, which suggests that the pattern of haemolymph circulation may have changed after landing, during the wasps' stay at the feeder. At initial landing at the feeders thoracic temperatures where equal to (three of eight tests) or lower (five of eight tests) than at final departure.The correlation of thorax temperature with food quality probably reflects the wasps' level of excitement and motivation to collect the food, which allows them to balance energetic investment with profitability of foraging and the needs of flight muscle performance and motility.     

Thermal Behaviour of Honeybees During Aggressive Interactions

We report here on the interrelationship of aggressive behaviour and thermoregulation in honeybees. Body temperature measurements were carried out without behavioural disturbance by infrared thermography. Guard bees, foragers, drones, and queens involved in aggressive interactions were always endothermic, i.e. had their flight muscles activated. Guards made differential use of their endothermic capacity. Mean thorax temperature was 34.2–35.1°C during examination of bees but higher during fights with wasps (37°C) or attack of humans (38.6°C). They usually cooled down when examining bees whereas examinees often heated up during prolonged interceptions (maximum >47°C). Guards neither adjusted their thorax temperature (and thus flight muscle function and agility) to that of examined workers, nor to that of drones, which were 2–7°C warmer. Guards examined cool bees (<33°C) longer than warmer ones, supporting the hypothesis that heating of examinees facilitates odour identification by guards, probably because of vapour pressure increase of semiochemicals with temperature. Guards in the core of aggressive balls clinged to the attacked insects to fix them and kill them by heat (maximum 46.5°C). Bees in the outer cluster layers resembled normal guards behaviourally and thermally. They served as active core insulators by heating up to 43.9°C. While balled wasps were cooler (maximum 42.5°C) than clinging guards balled bees behaved like examinees with maximum temperatures of 46.6°C, which further supports the hypothesis that the examinees heat up to facilitate odour identification.     

Preparation of Biologically Active Recombinant Human Progastrin1–80

The bacterial expression of human progastrin_6–80 has been reported previously [Baldwin, G.S. et al. (2001) J. Biol. Chem. 276: 7791-7796]. The aims of the present study were to prepare full-length recombinant human progastrin_1–80 and to compare its biological activity with that of progastrin_6–80 in vitro, to determine whether or not the N-terminal five amino acids contributed to activity. A fusion protein of glutathione-S-transferase and human progastrin_1–80 was expressed in Escherichia coli, collected on glutathione-agarose beads, and cleaved with enterokinase. Progastrin_1–80 was purified by reversed-phase and anion exchange HPLC and characterized by radioimmunoassay, amino acid sequencing, and mass spectrometry. No differences were detected in the extent of stimulation by progastrin_1–80 and progastrin_6–80 in proliferation and migration assays with the mouse gastric cell line IMGE-5. We conclude that residues 1–5 of progastrin_1–80 are not essential for biological activity.     

Activity and properties of CTP: cholinephosphate cytidylyltransferase in adult and fetal rat lung.

Cholinephosphate cytidylyltransferase (CTP : cholinephosphate cytidylyltransferase, EC 2.7.7.15) is located in both the microsomal and supernatant fractions of adult lung when the tissue is homogenized in 0.145 M NaCl. The activity is located predominantly in the supernatant fraction in fetal lung. Cholinephosphate cytidylyltransferase in the supernatant from fetal lung is stimulated 4- to 6-fold by the additions of total lung lipid. Serine phosphoglycerides and inositol phosphoglycerides specifically caused stimulation whereas choline phosphoglycerides and ethanolamine phosphoglycerides produced no stimulation. Lysophosphatidylcholine cause some stimulation, but only at high concentrations. A number of detergents were investigated. All produced inhibition except for the ampholytic detergent, miranol H2M which was not inhibitory. None of the detergents produced any stimulation of activity. Cytidylyltransferase activity in fetal lung when assayed in the absence of lipid is about 25% of the adult. The activity when assayed in the presence of lipid is equal or slightly higher than adult levels. The activity, measured without added phospholipid, increases 5- to 6-fold within 12 h after birth, to values higher than in the adult. The activity, measured in the presence of phospholipid, increased almost linearly from -2 day until +1 day. There is an inverse relationship between the concentration of phospholipid in the fetal lung supernatant and the degree of lipid stimulation. Chromatographic experiments with Biogel A 1.5 columns have shown that cytidylyltransferase can exist in two molecular sizes, a small molecular size that requires phospholipid for activity, and a larger molecular weight species which does not require the addition of phospholipid for activity. Fetal lung has a higher proportion of the low molecular weight form than adult lung. The small molecular weight species can be converted to the larger molecular weight form by the addition of phospholipids.     

Binding of discoidin domain receptor 2 to collagen I: an atomic force microscopy investigation

Collagens have recently been identified as ligands for discoidin domain receptors (DDR1 and DDR2), generating an interest in studying the properties of binding of DDR to its ligand. We are interested in the interaction of DDR2 with collagen I because of its potential role in liver fibrosis. Our in vitro binding assay utilizes DDR2-Fc fusion proteins, which can be clustered (multimerized) by use of antibodies to form DDR2 complexes. Binding of DDR2 complexes to collagen I coated on plastic plates was established by a microplate-based assay using Eu(3+)-labeled proteins and time-resolved fluorometry. Clustering of the DDR2-Fc with antibody was found to be requisite for binding to collagen in vitro. Using atomic force microscopy (AFM) in an aqueous environment, we characterized the surface topographies of DDR2 complexes and collagen I, and investigated binding of this receptor-ligand pair. We were able to image and identify binding of DDR2 complexes onto individual molecules of triple-helical collagen and provide insight into the number and locations of binding sites on collagen I. In most cases, a single receptor complex bound to a single collagen molecule and there were preferred DDR2 binding sites on the collagen I triple helix. These data were validated by rotary-replication transmission electron microscopy (TEM) of glycerol-sprayed samples.