Compression-induced changes in the shape and volume of the chondrocyte nucleus

Changes in cell shape and volume are believed to play a role in the process of mechanical signal transduction by chondrocytes in articular cartilage. One proposed pathway through which chondrocyte deformation may be transduced to an intracellular signal is through cytoskeletally mediated deformation of intracellular organelles, and more specifically, of the cell nucleus. In this study, confocal scanning laser microscopy was used to perform in situ three-dimensional morphometric analyses of the nuclei of viable condrocytes during controlled compression of articular cartilage explants from the canine patellofemoral groove. Unconfined compression of the tissue to a 15% surface-to-surface strain resulted in a significant decrease of chondrocyte height and volume by 14.7 ± 6.4 and 11.4 ± 8.4%, respectively, and of nuclear height and volume by 8.8 ± 6.2% and 9.8 ± 8.8%, respectively. Disruption of the actin cytoskeleton using cytochalasin D altered the relationship between matrix deformation and changes in nuclear height and shape, but not volume. The morphology and deformation behavior of the chondrocytes were not affected by cytochalasin treatment. These results suggest that the actin cytoskeleton plays an important role in the link between compression of the extracellular matrix and deformation of the chondrocyte nuclei and imply that chondrocytes and their nuclei undergo significant changes in shape and volume in vivo.     

Review and future prospects on the mechanisms related to cold stress resistance and tolerance in medicinal plants

Medicinal plants play important role in industrial production of medicines. Moreover, they consume without complicated processes around the world. They are considered as healthy cure without any harmful side effects at least among ordinary people. Cold stress is one the harmful abiotic stresses and constrains medicinal plants yielding geographically. Cold acclimation is a process that induces cold stress resistance in temperate plants. Various structural and morphological alterations are involved in this process. Also, enzymatic and non-enzymatic agents play role in cold acclimation. Cell membrane modification and compatible solutes accumulation and so many other changes occur through cold acclimation. Growing under different stressful conditions, medicinal plants synthesize different components such as metabolites. Moreover, ROS can be generated in plant cells under stressful conditions. The accumulation of bioactive components, biosynthesis of phytohormones, ion hemostasis, osmolyte (compatible solutes) accumulation and changes in nutrient uptake, root system modification and systemic resistance are some of new investigations that are considered in this review.     

Some 3-(4-Aminophenyl)pyrrolidine-2,5-diones as All- trans -retinoic Acid Metabolising Enzyme Inhibitors (RAMBAs)

A series of (±) -3-(4-aminophenyl) pyrrolidin-2,5-diones substituted in the 1-, 3- or 1,3- position with an aryl or long chain alkyl function are weak inhibitors of the metabolism of all-trans retinoic acid (RA) by rat liver microsomes (68-75% inhibition) compared with ketoconazole (85%). Further studies with the 1-cyclohexyl analogue (1) (IC 50 = 98.8 μM, ketoconazole, 22.15 μM) showed that it was not stereoselective in its inhibition. (±) - (1) was not an inhibitor of pig brain microsomal enzyme (ketoconazole, IC 50 = 20.9 μM), had little effect on human liver microsomal enzyme (19.3%, ketoconazole, 81.6%) or human placental microsomal enzyme (9.8%, ketoconazole 73.9%) but was a weak inhibitor of human and rat skin homogenates (52.6% and IC 50 = 211.6 μM respectively; ketoconazole, 38.8% and 85.95 μM). In RA-induced cell cultures of human male genital fibroblasts and HaCat cells, (±) - (1) was a weak inhibitor (c. 53% at 200 μM) whereas ketoconazole showed high potency (c. 65% at 0.625 μM and 0.25 μM respectively). The nature of the induced target enzyme is discussed.     

Inhibition of Retinoic Acid Metabolising Enzymes by 2-(4-aminophenylmethyl)-6-hydroxy-3,4-dihydronaphthalen-1(2H)-one and Related Compounds

In a search for inhibitors of all-trans retinoic acid (RA)-metabolising enzymes as potential agents for the treatment of skin conditions and cancer we have examined 2-(4-aminophenylmethyl)-6-hydroxy-3,4-dihydronaphthalen-1(2H)-one (5). Compound (5) is a moderate inhibitor of RA-metabolising enzymes in mammalian cadaverous tissue microsomes and homogenates as well as RA-induced enzymes in cultured human genital fibroblasts and HaCat cells. Overall (5) was more potent than or equipotent with ketoconazole, a standard inhibitor, in the cadaverous systems but less active towards the RA-induced cell culture systems. Examination of the data suggests that RA-induction generates metabolising enzymes not present in the cadaverous systems, which are more susceptible to inhibition by ketoconazole than (5).     

Genotyping of –374A/T, –429A/G,And 63 bp Ins/Del Polymorphisms of Rage By Rapid One-Step Hexaprimer Amplification Refractory Mutation System Polymerase Chain Reaction in Breast Cancer Patients

Several studies have focused on the RAGE genetic background and have demonstrated that its polymorphisms affect the receptor's activity, expression, and downstream signaling. However, there is only little information regarding RAGE polymorphism in breast cancer. In the present study, the authors studied RAGE polymorphisms in 71 patients with breast cancer and 93 healthy women. RAGE –374T/A, –429T/C, and 63 bp Ins/del polymorphisms were analyzed using a hexaprimer amplification refractory mutation system PCR (H-ARMS-PCR). The results showed that RAGE polymorphisms are not associated with breast cancer in the current study population. Larger studies are required to confirm these data in other populations.     

A conformationally sensitive residue on the cytoplasmic surface of serotonin transporter

Serotonin transporter (SERT) contains a single reactive external cysteine residue at position 109 (Chen, J. G., Liu-Chen, S., and Rudnick, G. (1997) Biochemistry 36, 1479-1486) and seven predicted cytoplasmic cysteines. A mutant of rat SERT (X8C) in which those eight cysteine residues were replaced by other amino acids retained approximately 32% of wild type transport activity and approximately 56% of wild type binding activity. In contrast to wild-type SERT or the C109A mutant, X8C was resistant to inhibition of high affinity cocaine analog binding by the cysteine reagent 2-(aminoethyl)methanethiosulfonate hydrobromide (MTSEA) in membrane preparations from transfected cells. Each predicted cytoplasmic cysteine residue was reintroduced, one at a time, into the X8C template. Reintroduction of Cys-357, located in the third intracellular loop, restored MTSEA sensitivity similar to that of C109A. Replacement of only Cys-109 and Cys-357 was sufficient to prevent MTSEA sensitivity. Thus, Cys-357 was the sole cytoplasmic determinant of MTSEA sensitivity in SERT. Both serotonin and cocaine protected SERT from inactivation by MTSEA at Cys-357. This protection was apparently mediated through a conformational change following ligand binding. Although both ligands bind in the absence of Na(+) and at 4 degrees C, their ability to protect Cys-357 required Na(+) and was prevented at 4 degrees C. The accessibility of Cys-357 to MTSEA inactivation was increased by monovalent cations. The K(+) ion, which is believed to serve as a countertransport substrate for SERT, was the most effective ion for increasing Cys-357 reactivity.