During oxygenic photosynthesis in cyanobacteria and chloroplasts of plants and eukaryotic algae, conversion of light energy to biologically useful chemical energy occurs in the specialized thylakoid membranes. Light-induced charge separation at the reaction centers of photosystems I and II, two multisubunit pigment-protein complexes in the thylakoid membranes, energetically drive sequential photosynthetic electron transfer reactions in this membrane system. In general, in the prokaryotic cyanobacterial cells, the thylakoid membrane is distinctly different from the plasma membrane. We have recently developed a two-dimensional separation procedure to purify thylakoid and plasma membranes from the genetically widely studied cyanobacterium Synechocystis sp. PCC 6803. Immunoblotting analysis demonstrated that the purified plasma membrane contained a number of protein components closely associated with the reaction centers of both photosystems. Moreover, these proteins were assembled in the plasma membrane as chlorophyll-containing multiprotein complexes, as evidenced from nondenaturing green gel and low-temperature fluorescence spectroscopy data. Furthermore, electron paramagnetic resonance spectroscopic analysis showed that in the partially assembled photosystem I core complex in the plasma membrane, the P700 reaction center was capable of undergoing light-induced charge separation. Based on these data, we propose that the plasma membrane, and not the thylakoid membrane, is the site for a number of the early steps of biogenesis of the photosynthetic reaction center complexes in these cyanobacterial cells.

PURPOSE To identify novel genetic markers predictive of clinical benefit from epidermal growth factor receptor-directed antibody therapy in patients with metastatic colorectal cancer (mCRC). PATIENTS AND METHODS Seventy-six consecutive patients who received cetuximab or panitumumab, either alone or in combination with chemotherapy, with available tumor tissue were included. Tumor tissue was tested for mutations at known hotspots in the KRAS, BRAF, PIK3CA, PIK3R1, AKT1, and PTEN genes by pyrosequencing. PTEN promoter methylation status was analyzed by methylation-specific PCR, and expression determined by immunohistochemistry (IHC). Forty-four patients had ≥ 4 weeks of therapy and were considered for clinical correlates. RESULTS Consistent with previous studies, KRAS gene mutations were associated with a shorter progression free (PFS) and overall survival (OS). Among the KRAS wild type patients, preservation of PTEN expression and PIK3CA WT status was associated with improved OS (median OS, 80.4 vs 32.5 weeks, HR: 0.33, p=0.0008) and a trend towards improved PFS (median PFS, 24.8 vs 15.2 weeks, HR: 0.51, p=0.06), compared to PTEN negative or PIK3CA mutant tumors. PTEN methylation was more common in the metastases than the primary (p=0.02). Simultaneous presence of methylation and mutation in the PTEN gene was associated with IHC negativity (p=0.026). CONCLUSION In addition to KRAS mutation, loss of PTEN expression (by IHC) and PIK3CA mutation is likely to be predictive of lack of benefit to anti-EGFR therapy in mCRC. PTEN promoter methylation and mutation status was predictive of PTEN expression, and may be utilized as an alternative means of predicting response to EGFR-targeted therapy.

Ultra high molecular weight polyethylene is widely used as a bearing surface in prosthetic arthroplasty. Over time the generation of implant-derived wear particles can initiate an inflammatory reaction characterized by periprosthetic inflammation and ultimately bone resorption at the prosthetic bone interface. Herein we present evidence that the different sized particles as well as the different length alkane polymers generated by implant wear leads to a two component inflammatory response. Polymeric alkane structures, with side chain oxidations, directly bind and activate the TLR-1/2 signaling pathway. Whereas micron and nanometer sized particulate debris are extensively phagocyted and induce enlargement, fusion and disruption of endosomal compartments. The resulting lysosomal damage and subsequent enzymatic leakage induces the NALP3 inflammasome activation as determined by cathepsins S and B cytosolic release, Caspase 1 activation and processing of pro-IL-1β, and pro-IL-18. These two processes synergistically results in the initiation of a strong inflammatory response with consequent cellular necrosis and extra-cellular matrix degradation.

Medical therapy of patients with malignancy requires a paradigm shift through development of new drugs with a good safety record and novel mechanisms of activity. While there is no dearth of such molecules, one particular agent, “reovirus” is promising by its ability to target cancer cells with aberrant signaling pathways. This double stranded RNA virus has been therapeutically formulated and has rapidly progressed from pre-clinical validation of anti cancer activity to a phase III registration study in platinum refractory metastatic squamous cell carcinoma of the head and neck. During this process, reovirus has demonstrated safety both as a single agent when administered intratumorally and intravenously, as well as in combination therapy, with multiple chemotherapeutics such as gemcitabine, carboplatin/paclitaxel, and docetaxel; and similarly with radiation. The scientific rationale for its development as an anticancer agent stems from the fact that it preferentially replicates in and induces lyses of cells with an activated Kras pathway. As documented in many previous studies, the initial observation of greater tropism in Kras compromised situation might certainly not be the sole and possibly not even the predominant reason for enhanced virulence. All the same, scientists have emphasized on Kras optimistically due to its high prevalence in various types of cancers. Incidence of Kras mutation has been found to be highest in pancreatic cancer (85–90%) followed by colorectal (35–45%) and lung (25–30%). Reovirus, in fact has the potential not only as a therapy but also as a tool to unravel the aberrant cellular pathway leading to carcinogenicity.