Development and verification of a three-dimensional (3D) breast cancer tumor model composed of circulating tumor cell (CTC) subsets

Molecular Biology Reports - Breast cancer is one of the most common cancer types among women in which early tumor invasion leads to metastases and death. EpCAM (epithelial cellular adhesion...     

Age-related changes of antioxidant enzyme activities, glutathione status and lipid peroxidation in rat erythrocytes after heat stress

The aim of this study was to determine whether exposure to heat stress would lead to oxidative stress and whether this effect varied with different exposure periods. We kept 1-, 6- and 12-month-old male Wistar rats at an ambient temperature of either 22 degrees C or 40 degrees C for 3 and 7 days and measured glucose-6-phosphate dehydrogenase (G-6-PD), Cu,Zn-superoxide dismutase (Cu,Zn-SOD), catalase (CAT), selenium-dependent glutathione peroxidase (Se-GSH-Px) and glutathione-S-transferase (GST) activities and levels of thiobarbituric acid-reactive substances (TBARS), reduced glutathione (GSH) and oxidized glutathione (GSSG) in erythrocytes and determined GSH/GSSG ratio, total glutathione and the redox index. G-6-PD and CAT activities were found to be significantly increased in 1- and 6-month-old rats after 3 and 7 days of heat stress, but G-6-PD activities decreased in 12-month-old rats. Cu, Zn-SOD activity decreased in 1-month-old rats after heat stress, whereas it increased in 6- and 12-month-old rats. GST activity increased in all groups. GSH and total GSH levels and GSH/GSSG ratios decreased in 1- and 6-month-old rats but they increased in 12-month-old rats after heat stress. GSSG levels increased in 1- and 6-month-old rats but decreased in 12-month-old rats after heat stress. TBARS levels increased in all groups. Seven days of stress is more effective in altering enzyme activities and levels of GSH, GSSG and TBARS. When the effects of both heat stress and aging were examined together, it was interesting to note that they mostly influenced G-6-PD activity.     

The protective effect of lisinopril on membrane-bound enzymes in myocardial preservation

A number of studies have reported that oxidant stress reduces the activity of isolated Na(+)-K(+) ATPase and Ca(2+) ATPase which are known to affect the cell membrane integrity. The aim of the study is to determine whether the administration of lisinopril is able to protect the membrane-bound enzyme levels in isolated guinea pig hearts and also ascertain whether or not a relationship exists between oxygen free radicals and membrane bound Na(+)-K(+) ATPase and Ca(2+) ATPase. Forty guinea pig hearts were studied in an isolated Krebs-Henseleit solution-perfused Langendorff cardiac model. In all groups cardioplegic arrest was achieved by administering St. Thomas' Hospital cardioplegic solution (STHCS). Group 1 (control, n=10) received only STHCS. Group 2 (n=10) were arrested with lisinopril (l micromol l(-1)) added STHCS. Group 3 (n=10) were pretreated with oral lisinopril (0.2 mg kg(-1) twice a day) for 10 days and then arrested with STHCS. Group 4 were also pretreated with oral lisinopril (0.2 mg kg(-1) twice a day for 10 days), arrested with STHCS and reperfused with lisinopril added to Krebs-Henseleit solution (l micromol l(-1)). Hearts were subjected to normothermic global ischaemia for 90 min and then reperfused at 37 degrees C. Pretreatment and addition of lisinopril in the reperfusion buffer improved the levels of membrane-bound enzymes. When the treated groups were compared with control hearts, the best results were achieved in group 4. The Na(+)-K(+) and Ca(2+) ATPase levels increased from 466.38+/-5.99 to 560.12+/-18.02 and 884.69+/-9.13 to 1287.71+/-13.01 nmolPi mg(-1) protein h(-1) respectively (p<0.05). These results suggest that lisinopril protects the cell membrane integrity and lessens free radical-induced oxidant stress.     

Group behaviour in physical,chemical and biological systems

Groups exhibit properties that either are not perceived to exist, or perhaps cannot exist, at the individual level. Such ‘emergent’ properties depend on how individuals interact, both among themselves and with their surroundings. The world of everyday objects consists of material entities. These are, ultimately, groups of elementary particles that organize themselves into atoms and molecules, occupy space, and so on. It turns out that an explanation of even the most commonplace features of this world requires relativistic quantum field theory and the fact that Planck’s constant is discrete, not zero. Groups of molecules in solution, in particular polymers (‘sols’), can form viscous clusters that behave like elastic solids (‘gels’). Sol-gel transitions are examples of cooperative phenomena. Their occurrence is explained by modelling the statistics of inter-unit interactions: the likelihood of either state varies sharply as a critical parameter crosses a threshold value. Group behaviour among cells or organisms is often heritable and therefore can evolve. This permits an additional, typically biological, explanation for it in terms of reproductive advantage, whether of the individual or of the group. There is no general agreement on the appropriate explanatory framework for understanding group-level phenomena in biology.     

In vitro inhibitory effects of some heavy metals on human erythrocyte carbonic anhydrases

The inhibition of two human carbonic anhydrase (HCA, EC 4.2.1.1) isozymes, the cytosolic HCA I and II, with heavy metal salts of Pb(II), Co(II) and Hg(II) has been investigated. Human erythrocyte CA-I isozyme was purified with a specific activity of 920 EUmg(-1) and a yield of 30% and CA-II isozyme was purified with a specific activity of 8000 EUmg(-1) and a yield of 40% using Sepharose-4B-L tyrosine-sulfanilamide affinity gel chromatography. The overall purification was approximately 104-fold for HCA-I and 900-fold for HCA-II. The inhibitory effects of different heavy metals (lead, cobalt and mercury) on CA activity were determined at low concentrations using the esterase method under in vitro conditions. Ki values for these metals were calculated from Lineweaver-Burk graphs as 1.0, 3.22 and 1.45 mM for HCA-I and 0.059, 1.382 and 0.32 mM for HCA-II respectively. Lead was a noncompetitive inhibitor for HCA-I and competitive for HCA-II, cobalt was competitive for HCA-I and noncompetitive for HCA-II and mercury was uncompetitive for both HCA-I and HCA-II. Lead was the best inhibitor for both HCA-I and HCA-II.     

Risk assessment strategies for transgenic plants

Advances in recombinant DNA technology have created advantages for the development of plants with high agro-economical values. Since the production of transgenic plants, some issues concerning the safe use of these plants and their products have been under debate throughout the world. In this respect, the potential risks and benefits of transgenic plants need to be evaluated objectively. Risk assessment of transgenic crops is a basic prerequisite for monitoring the possible risks that could arise upon the release and use of transgenic plants. To get a meaningful tool for decision making, risk assessment needs to be carried out in a scientific sound and transparent manner. There are specific governmental regulations in many countries for the safety assessment of genetically modified (GM) crops. Furthermore, there are some international agreements, which regulate the cultivation and commercialization of transgenic plants and their derivatives. Internationally accepted risk assessment strategies have been performed to evaluate the safe use of a large variety of GM crops. The main objectives of these regulations and risk assessment strategies are focused to protect human/animal health and the environment.     

Genetic differentiation between clone collections and natural populations of European black poplar (<Emphasis Type="Italic">Populus nigra</Emphasis> L.) in turkey

The European black poplar (Populus nigra L.) is an ecologically and economically important tree species for Turkey. The important and major genetic resources of species for future breeding and ex situ conservation purposes have been archived in a clone bank in Ankara by selecting clones from natural populations and old plantations throughout Turkey. There is no study to date assessing genetic composition these materials. Two-hundred-thirty-three P. nigra clones from six geographic region of Turkey (clone collection populations), and 32 trees from two natural populations (Tunceli and Melet) were genotyped by using 12 nuclear microsatellite DNA markers. There were nine clones which duplicated in various frequencies. The analysis carried out with removal of the duplicated clones revealed a moderately high genetic diversity in studied populations. The observed heterozygosities ranged from 0.59 in Tunceli natural to 0.69 in Central Anatolia clone collection populations. In general, there was excess of heterozygosity in the studied populations. Populations composed of clone collections were significantly differentiated from natural populations (F _ST = 0.17), while there was little differentiation among those populations in the clone collection (F _ST = 0.03). Two distantly located natural populations with small sizes also differed from each other (F _ST = 0.17). Genetic structure analysis revealed two distinct groups (clone collection vs natural populations) with very high membership values (>92%). Clone collection populations had high level of admixture while natural populations had homogenous genetic structure. The presence of large number of clonal duplication, reduced genetic differentiation, and high level of admixture in clone collection populations indicate that genetic resources of European black poplar were highly degraded through genetic erosion and pollution caused by intensive cultural practices and extensive dispersal of clonal materials. To understand genetic diversity and its structural pattern thoroughly in the six clone collection populations, a further study with extensive and systematic sampling of European black poplar populations in major river ecosystems in Turkey will be useful.     

Is local distribution of the epiphytic lichen <Emphasis Type="Italic">Lobaria pulmonaria</Emphasis> limited by dispersal capacity or habitat quality?

By surveying and re-surveying 12 forest sites in southern Sweden for the epiphytic lichen Lobaria pulmonaria with a 9-year interval, and measuring tree-related habitat quality variables, we have investigated whether the local distribution of the lichen is limited by poor dispersal capacity or by habitat quality. Dispersal distances were measured indirectly as the distances between colonised trees and the nearest trees occupied by L. pulmonaria in both 1992 and 2001. To compare habitat quality between trees occupied by L. pulmonaria and neighbouring control trees, we recorded tree species and measured age and growth rate of trees, light conditions, bark structure and bryophyte cover. The estimated mean dispersal distance was 35 m, with a recorded maximum of 75 m. Occupied trees were larger and had a larger cover of bryophytes than unoccupied trees of similar size. The results indicate that dispersal capacity probably is the most important factor in limiting the local distribution of L. pulmonaria, but habitat-quality factors may be important on a smaller spatial scale.