Hemiarthroplasty of hip joint: An experimental validation using porcine acetabulum

Biphasic properties of articular cartilage allow it to be an excellent bearing material and have been studied through several simplified experiments as well as finite element modelling. However, three-dimensional biphasic finite element (FE) models of the whole joint are rare. The current study was carried out to experimentally validate FE methodology for modelling hemiarthroplasty. Material properties such as equilibrium elastic modulus and permeability of porcine acetabular cartilage were initially derived by curve-fitting an experimental deformation curve with that obtained using FE. These properties were then used in the hemiarthroplasty hip joint modelling. Each porcine acetabular cup was loaded with 400N using a 34mm diameter CoCr femoral head. A specimen-specific FE model of each acetabular cup was created using μCT and a series of software processes. Each model was analysed under conditions similar to those tested experimentally. Contact stresses and contact areas predicted by the model, immediately after loading, were then compared with the corresponding experimentally measured values. Very high peak contact stresses (maximum experimental: 14.09MPa) were recorded. A maximum difference of 12.42% was found in peak contact stresses. The corresponding error for contact area was 20.69%. Due to a fairly good agreement in predicted and measured values of contact stresses and contact areas, the integrated methodology developed in this study can be used as a basis for future work. In addition, FE predicted total fluid load support was around 80% immediately after loading. This was lower than that observed in conforming contact problems involving biphasic cartilage and was due to a smaller local contact area and variable clearance making fluid exudation easier.     

Draft Genome Sequence of the Methyl Parathion (Pesticide) Degrading Bacterium Pseudomonas spp. MR3

Pseudomonas spp. MR3 was isolated from the surrounding soil of pesticide manufacturing industries of Ankleshwar, Gujarat. Under laboratory conditions these microbes were able to degrade up to 500 ppm of methyl parathion within 72 h. Genome sequencing of Pseudomonas spp. MR3 was carried out inIon Torrent (PGM), next generation sequencer. The data obtained revealed 1,268 contigs with genome size of 2.99 Mb and G + C content of 60.9 %. The draft genome sequence of strain MR3 will be helpful in studying the genetic pathways involved in the degradation of several pesticides.     

EP4 mediates PGE2 dependent cell survival through the PI3 kinase/AKT pathway

The anti-apoptotic effect of PGE(2) was examined in Jurkat cells (human T-cell leukemia) by incubation with PGE(2) (5 nM) prior to treatment with the cancer chemotherapeutic agent camptothecin. Apoptosis was evaluated by caspase-3 activity in cell extracts and flow cytometry of propidium iodide-labeled cells. Pre-incubation with PGE(2) reduced camptothecin-induced caspase activity by 30% and apoptosis by 35%, respectively. Pharmacological data demonstrate that the EP4 receptor is responsible for mediating the protection from camptothecin-induced apoptosis. Pre-treatment of the cells with the EP4 antagonist (EP4A) prior to PGE(2) and camptothecin abolished the increased survival effect of PGE(2). Specific inhibition of the downstream of PI3 kinase or AKT/protein kinase but not protein kinase A prevents the observed increase in cell survival elicited by PGE(2). These findings have critical implications regarding the mechanism and potential application of PGE(2) receptor specific inhibition in cancer therapy.     

Characterization of Mimban maize landrace from North-Eastern Himalayan region using microsatellite markers

The North-Eastern Himalayan (NEH) region of India is endowed with rich maize genetic resources which is important from both genetics and evolutionary viewpoints. Mimban landrace of maize is a popular choice in Mizoram as food among the locals due to its stickiness caused by recessive wx1 gene resulting in high amylopectin in the grains. In the present study, a set of 24 Mimban accessions possessing high amylopectin (mean 89.72%, range 80.2–93.7%) content were analyzed. 93 SSRs markers generated a total of 334 alleles with a range of 2–9 and mean of 3.59 alleles per locus. Polymorphism information content varied from 0.117 to 0.829 with an average of 0.528. A total of 20 unique and 24 rare alleles were detected. Twenty-seven major alleles with individual frequencies exceeding 0.70 were also identified across the accessions. Cluster analyses classified 24 genotypes into three major clusters each having 2, 14 and 9 accessions. The clustering pattern was largely congruent with the geographical information. Diverse origin of the accessions was also depicted by the SSR based principal coordinate analysis. These accessions with high amylopectin content from diverse clusters may be crossed to derive heterotic hybrid and also might be used for novel gene identification. Thus information generated here possesses great potential in their utilization in the waxy corn genomics and breeding and emphasizes the need for further exploration of unique trait specific genepool from unexplored areas. This is the first report of molecular characterization of Mimban landrace accessions from NEH region.

     

Cyclosporin A--a review on fermentative production, downstream processing and pharmacological applications

In present times, the immunosuppressants have gained considerable importance in the world market. Cyclosporin A (CyA) is a cyclic undecapeptide with a variety of biological activities including immunosuppressive, anti-inflammatory, antifungal and antiparasitic properties. CyA is produced by various types of fermentation techniques using Tolypocladium inflatum. In the present review, we discuss the biosynthetic pathway, fermentative production, downstream processing and pharmacological activities of CyA.     

Characterization of Enantiomeric Bile Acid-induced Apoptosis in Colon Cancer Cell Lines

Bile acids are steroid detergents that are toxic to mammalian cells at high concentrations; increased exposure to these steroids is pertinent in the pathogenesis of cholestatic disease and colon cancer. Understanding the mechanisms of bile acid toxicity and apoptosis, which could include nonspecific detergent effects and/or specific receptor activation, has potential therapeutic significance. In this report we investigate the ability of synthetic enantiomers of lithocholic acid (ent-LCA), chenodeoxycholic acid (ent-CDCA), and deoxycholic acid (ent-DCA) to induce toxicity and apoptosis in HT-29 and HCT-116 cells. Natural bile acids were found to induce more apoptotic nuclear morphology, cause increased cellular detachment, and lead to greater capase-3 and -9 cleavage compared with enantiomeric bile acids in both cell lines. In contrast, natural and enantiomeric bile acids showed similar effects on cellular proliferation. These data show that bile acid-induced apoptosis in HT-29 and HCT-116 cells is enantiospecific, hence correlated with the absolute configuration of the bile steroid rather than its detergent properties. The mechanism of LCA- and ent-LCA-induced apoptosis was also investigated in HT-29 and HCT-116 cells. These bile acids differentially activate initiator caspases-2 and -8 and induce cleavage of full-length Bid. LCA and ent-LCA mediated apoptosis was inhibited by both pan-caspase and selective caspase-8 inhibitors, whereas a selective caspase-2 inhibitor provided no protection. LCA also induced increased CD95 localization to the plasma membrane and generated increased reactive oxygen species compared with ent-LCA. This suggests that LCA/ent-LCA induce apoptosis enantioselectively through CD95 activation, likely because of increased reactive oxygen species generation, with resulting procaspase-8 cleavage.Bile acids are physiologic steroids that are necessary for the proper absorption of fats and fat-soluble vitamins. Their ability to aid in these processes is largely due to their amphipathic nature and thus their ability to act as detergents. Despite the beneficial effects, high concentrations of bile acids are toxic to cells (1-11). High fat western diets induce extensive recirculation of the bile acid pool, resulting in increased exposure of the colonic epithelial cells to these toxic steroids (12, 13). A high fat diet is also a risk factor for colon carcinogenesis; increased bile acid exposure is responsible for some of this risk. Bile acids can contribute to both colon cancer formation and progression, and their effects on colonic proliferation and apoptosis aid this process by disrupting the balance between cell growth and cell death, as well as helping to select for bile acid-resistant cells (14, 15).In colonocyte-derived cell lines bile acid-induced apoptosis is thought to proceed through mitochondrial destabilization with resulting mitochondrial permeability transition formation and cytochrome c release as well as generation of oxidative stress (1, 9-11). Bile acid-induced apoptosis has also been extensively explored in hepatocyte derived cell lines with mechanisms including mitochondria dysfunction (16-23), endoplasmic reticulum stress (24), ligand-independent activation of death receptor pathways (18, 25-28), and modulation of cellular apoptotic and anti-apoptotic Bcl-2 family proteins (29).Although ample evidence exists for multiple mechanisms of bile acid-induced apoptosis, the precise interactions responsible for initiating these apoptotic pathways are still unclear. Bile acids have been shown to interact directly with specific receptors (30, 31). These steroids can also initiate cellular signaling through nonspecific membrane perturbations (32), and evidence exists showing that other simple detergents (i.e. Triton X-100) are capable of inducing caspase cleavage nonspecifically with resultant apoptosis (33). Therefore, hydrophobic bile acids may interact nonspecifically with cell membranes to alter their physical properties, bind to receptors specific for these steroids, or utilize a combination of both specific and nonspecific interactions to induce apoptosis.Bile acid enantiomers could be useful tools for elucidating mechanisms of bile acid toxicity and apoptosis. These enantiomers, known as ent-bile acids, are synthetic nonsuperimposable mirror images of natural bile acids with identical physical properties except for optical rotation. Because bile acids are only made in one absolute configuration naturally, ent-bile acids must be constructed using a total synthetic approach. Recently we reported the first synthesis of three enantiomeric bile acids: ent-lithocholic acid (ent-LCA),² ent-chenodeoxycholic acid (ent-CDCA), and ent-deoxycholic acid (ent-DCA) (Fig. 1) (34, 35). Enantiomeric bile acids have unique farnesoid X receptor, vitamin D receptor, pregnane X receptor, and TGR5 receptor activation profiles compared with the corresponding natural bile acids (34). This illustrates that natural and enantiomeric bile acids interact differently within chiral environments because of their distinct three-dimensional configurations (Fig. 1). Despite these differences in chiral interactions, ent-bile acids have physical properties identical to those of their natural counterparts including solubility and critical micelle concentrations (34, 35). With different receptor interaction profiles and identical physical properties compared with natural bile acids, ent-bile acids are ideal compounds to differentiate between the receptor-mediated and the non-receptor-mediated functions of natural bile acids.Open in a separate windowFIGURE 1.Natural and enantiomeric bile acids. Structures and three-dimensional projection views of natural LCA, CDCA, DCA, and their enantiomers (ent-LCA, ent-CDCA, and ent-DCA). The three-dimensional ent-steroid structure is rotated 180° around the long axis for easier comparison with the natural steroid.In this study we explore the enantioselectivity of LCA-, CDCA-, and DCA-mediated toxicity and apoptosis in two human colon adenocarcinoma cell lines, HT-29 and HCT-116. Because the mechanism of natural LCA induced apoptosis has never been characterized, we then examined in more detail LCA- and ent-LCA-mediated apoptosis in colon cancer cells. These studies will not only explore the LCA apoptotic mechanism but will also determine whether ent-LCA signals through similar cellular pathways.     

Curcumin induces cell death in esophageal cancer cells through modulating Notch signaling

Background

Curcumin inhibits the growth of esophageal cancer cell lines; however, the mechanism of action is not well understood. It is becoming increasingly clear that aberrant activation of Notch signaling has been associated with the development of esophageal cancer. Here, we have determined that curcumin inhibits esophageal cancer growth via a mechanism mediated through the Notch signaling pathway.

Methodology/Principal Findings

In this study, we show that curcumin treatment resulted in a dose and time dependent inhibition of proliferation and colony formation in esophageal cancer cell lines. Furthermore, curcumin treatment induced apoptosis through caspase 3 activation, confirmed by an increase in the ratio of Bax to Bcl2. Cell cycle analysis demonstrated that curcumin treatment induced cell death and down regulated cyclin D1 levels. Curcumin treatment also resulted in reduced number and size of esophagospheres. Furthermore, curcumin treatment led to reduced Notch-1 activation, expression of Jagged-1 and its downstream target Hes-1. This reduction in Notch-1 activation was determined to be due to the down-regulation of critical components of the γ-secretase complex proteins such as Presenilin 1 and Nicastrin. The combination of a known γ-secretase inhibitor DAPT and curcumin further decreased proliferation and induced apoptosis in esophageal cancer cells. Finally, curcumin treatment down-regulate the expressions of Notch-1 specific microRNAs miR-21 and miR-34a, and upregulated tumor suppressor let-7a miRNA.

Conclusion/Significance

Curcumin is a potent inhibitor of esophageal cancer growth that targets the Notch-1 activating γ-secretase complex proteins. These data suggest that Notch signaling inhibition is a novel mechanism of action for curcumin during therapeutic intervention in esophageal cancers.