BIODIESEL – ALTERNATIVE FUEL

Ograničene količine nafte, za čiju se nabavku izdvajaju značajna financijska sredstva, postale su bitnim čimbenikom intenziviranja pronalaženja i uporabe alternativnih vrsta goriva. Biodizelsko gorivo koristi se za pogon dizel motora, a proizvodi se iz biljnih ulja, životinjskih masti te rabljenog jestivog ulja. Uz značajan ekonomski, gospodarski i strateški interes proizvodnje, proizvodnja i primjena biodizelskoga goriva poglavito je značajna s obzirom na očuvanje okoliša. Nadalje, dobri uvjeti za proizvodnju uljane repice u Republici Hrvatskoj upućuju na samodostatnost proizvodnje biodizelskog goriva za poljoprivrednu proizvodnju, mogućnost njenog intenziviranja te mogućnost zapošljavanja određenog broja ljudi, kako u poljoprivrednoj proizvodnji, tako i u pogonima za proizvodnju biodizelskog goriva. U radu se daje pregled proizvodnje biodizelskog goriva, pregled njegovih karakteristika i utjecaja na karakteristike dizel motora te utjecaj biodizela na okoliš.A limited quantity of oil, the purchase of which also involves major expenses has become an important factor for intensive search and use of alternative fuels. Biodiesel is used in diesel engines, and is manufactured from vegetable oils, animal fats and recycled edible oils. The production and use of biodiesel are very important not only because of its economic and strategic connotations but also because of its environmental advantages. Favourable conditions in Croatia give good opportunities for a self-sufficient oil rape production, possibility for its intensification and employment of a number of people in both the agricultural production and biodiesel production plants. This paper presents a survey of the biodiesel fuel production, the characteristics and impacts it has on the biodiesel engine features as well as its impact on the environment

Small Molecule Inhibition of HIV-1–Induced MHC-I Down-Regulation Identifies a Temporally Regulated Switch in Nef Action

Nef assembles a multi-kinase complex triggering MHC-I down-regulation. We identify an inhibitor that blocks MHC-I down-regulation, identifying a temporally regulated switch in Nef action from directing MHC-I endocytosis to blocking cell surface delivery. These findings challenge current dogma and reveal a regulated immune evasion program

Acetate-induced apoptosis in colorectal carcinoma cells involves lysosomal membrane permeabilization and cathepsin D release

Colorectal carcinoma (CRC) is one of the most common causes of cancer-related mortality. Short-chain fatty acids secreted by dietary propionibacteria from the intestine, such as acetate, induce apoptosis in CRC cells and may therefore be relevant in CRC prevention and therapy. We previously reported that acetic acid-induced apoptosis in Saccharomyces cerevisiae cells involves partial vacuole permeabilization and release of Pep4p, the yeast cathepsin D (CatD), which has a protective role in this process. In cancer cells, lysosomes have emerged as key players in apoptosis through selective lysosomal membrane permeabilization (LMP) and release of cathepsins. However, the role of CatD in CRC survival is controversial and has not been assessed in response to acetate. We aimed to ascertain whether LMP and CatD are involved in acetate-induced apoptosis in CRC cells. We showed that acetate per se inhibits proliferation and induces apoptosis. More importantly, we uncovered that acetate triggers LMP and CatD release to the cytosol. Pepstatin A (a CatD inhibitor) but not E64d (a cathepsin B and L inhibitor) increased acetateinduced apoptosis of CRC cells, suggesting that CatD has a protective role in this process. Our data indicate that acetate induces LMP and subsequent release of CatD in CRC cells undergoing apoptosis, and suggest exploiting novel strategies using acetate as a prevention/therapeutic agent in CRC, through simultaneous treatment with CatD inhibitors.This work was supported by the Fundação para a Ciência e Tecnologia (FCT) research project PTDC/BIA-BCM/69448/2006 and FCT PhD grants for SA (SFRH/BD/64695/2009) and CO (SFRH/BD/77449/2011). This work was also supported by FEDER through POFC—COMPETE, and by national funds from FCT through the project PEst-C/BIA/UI4050/2011

The propeptide of yeast cathepsin D inhibits programmed necrosis

The lysosomal endoprotease cathepsin D (CatD) is an essential player in general protein turnover and specific peptide processing. CatD-deficiency is associated with neurodegenerative diseases, whereas elevated CatD levels correlate with tumor malignancy and cancer cell survival. Here, we show that the CatD ortholog of the budding yeast Saccharomyces cerevisiae (Pep4p) harbors a dual cytoprotective function, composed of an anti-apoptotic part, conferred by its proteolytic capacity, and an anti-necrotic part, which resides in the protein's proteolytically inactive propeptide. Thus, deletion of PEP4 resulted in both apoptotic and necrotic cell death during chronological aging. Conversely, prolonged overexpression of Pep4p extended chronological lifespan specifically through the protein's anti-necrotic function. This function, which triggered histone hypoacetylation, was dependent on polyamine biosynthesis and was exerted via enhanced intracellular levels of putrescine, spermidine and its precursor S-adenosyl-methionine. Altogether, these data discriminate two pro-survival functions of yeast CatD and provide first insight into the physiological regulation of programmed necrosis in yeast

Nef Alleles from All Major HIV-1 Clades Activate Src-Family Kinases and Enhance HIV-1 Replication in an Inhibitor-Sensitive Manner

The HIV-1 accessory factor Nef is essential for high-titer viral replication and AIDS progression. Nef function requires interaction with many host cell proteins, including specific members of the Src kinase family. Here we explored whether Src-family kinase activation is a conserved property of Nef alleles from a wide range of primary HIV-1 isolates and their sensitivity to selective pharmacological inhibitors. Representative Nef proteins from the major HIV-1 subtypes A1, A2, B, C, F1, F2, G, H, J and K strongly activated Hck and Lyn as well as c-Src to a lesser extent, demonstrating for the first time that Src-family kinase activation is a highly conserved property of primary M-group HIV-1 Nef isolates. Recently, we identified 4-amino substituted diphenylfuropyrimidines (DFPs) that selectively inhibit Nef-dependent activation of Src-family kinases as well as HIV replication. To determine whether DFP compounds exhibit broad-spectrum Nef-dependent antiretroviral activity against HIV-1, we first constructed chimeric forms of the HIV-1 strain NL4-3 expressing each of the primary Nef alleles. The infectivity and replication of these Nef chimeras was indistinguishable from that of wild-type virus in two distinct cell lines (U87MG astroglial cells and CEM-T4 lymphoblasts). Importantly, the 4-aminopropanol and 4-aminobutanol derivatives of DFP potently inhibited the replication of all chimeric forms of HIV-1 in both U87MG and CEM-T4 cells in a Nef-dependent manner. The antiretroviral effects of these compounds correlated with inhibition of Nef-dependent activation of endogenous Src-family kinases in the HIV-infected cells. Our results demonstrate that the activation of Hck, Lyn and c-Src by Nef is highly conserved among all major clades of HIV-1 and that selective targeting of this pathway uniformly inhibits HIV-1 replication

Molecular Design, Functional Characterization and Structural Basis of a Protein Inhibitor Against the HIV-1 Pathogenicity Factor Nef

Increased spread of HIV-1 and rapid emergence of drug resistance warrants development of novel antiviral strategies. Nef, a critical viral pathogenicity factor that interacts with host cell factors but lacks enzymatic activity, is not targeted by current antiviral measures. Here we inhibit Nef function by simultaneously blocking several highly conserved protein interaction surfaces. This strategy, referred to as “wrapping Nef”, is based on structure-function analyses that led to the identification of four target sites: (i) SH3 domain interaction, (ii) interference with protein transport processes, (iii) CD4 binding and (iv) targeting to lipid membranes. Screening combinations of Nef-interacting domains, we developed a series of small Nef interacting proteins (NIs) composed of an SH3 domain optimized for binding to Nef, fused to a sequence motif of the CD4 cytoplasmic tail and combined with a prenylation signal for membrane association. NIs bind to Nef in the low nM affinity range, associate with Nef in human cells and specifically interfere with key biological activities of Nef. Structure determination of the Nef-inhibitor complex reveals the molecular basis for binding specificity. These results establish Nef-NI interfaces as promising leads for the development of potent Nef inhibitors

Automatic lung segmentation of magnetic resonance images: A new approach applied to healthy volunteers undergoing enhanced Deep-Inspiration-Breath-Hold for motion-mitigated 4D proton therapy of lung tumors.

BACKGROUND AND PURPOSE Respiratory suppression techniques represent an effective motion mitigation strategy for 4D-irradiation of lung tumors with protons. A magnetic resonance imaging (MRI)-based study applied and analyzed methods for this purpose, including enhanced Deep-Inspiration-Breath-Hold (eDIBH). Twenty-one healthy volunteers (41-58 years) underwent thoracic MR scans in four imaging sessions containing two eDIBH-guided MRIs per session to simulate motion-dependent irradiation conditions. The automated MRI segmentation algorithm presented here was critical in determining the lung volumes (LVs) achieved during eDIBH. MATERIALS AND METHODS The study included 168 MRIs acquired under eDIBH conditions. The lung segmentation algorithm consisted of four analysis steps: (i) image preprocessing, (ii) MRI histogram analysis with thresholding, (iii) automatic segmentation, (iv) 3D-clustering. To validate the algorithm, 46 eDIBH-MRIs were manually contoured. Sørensen-Dice similarity coefficients (DSCs) and relative deviations of LVs were determined as similarity measures. Assessment of intrasessional and intersessional LV variations and their differences provided estimates of statistical and systematic errors. RESULTS Lung segmentation time for 100 2D-MRI planes was ∼ 10 s. Compared to manual lung contouring, the median DSC was 0.94 with a lower 95 % confidence level (CL) of 0.92. The relative volume deviations yielded a median value of 0.059 and 95 % CLs of -0.013 and 0.13. Artifact-based volume errors, mainly of the trachea, were estimated. Estimated statistical and systematic errors ranged between 6 and 8 %. CONCLUSIONS The presented analytical algorithm is fast, precise, and readily available. The results are comparable to time-consuming, manual segmentations and other automatic segmentation approaches. Post-processing to remove image artifacts is under development

Faraday cup for commissioning and quality assurance for proton pencil beam scanning beams at conventional and ultra-high dose rates.

Recently, proton therapy treatments delivered with ultra-high dose rates have been of high scientific interest, and the Faraday cup (FC) is a promising dosimetry tool for such experiments. Different institutes use different FC designs, and either a high voltage guard ring, or the combination of an electric and a magnetic field is employed to minimize the effect of secondary electrons. The authors first investigate these different approaches for beam energies of 70, 150, 230 and 250 MeV, magnetic fields between 0 and 24 mT and voltages between -1000 and 1000 V. When applying a magnetic field, the measured signal is independent of the guard ring voltage, indicating that this setting minimizes the effect of secondary electrons on the reading of the FC. Without magnetic field, applying the negative voltage however decreases the signal by an energy dependent factor up to 1.3% for the lowest energy tested and 0.4% for the highest energy, showing an energy dependent response. Next, the study demonstrates the application of the FC up to ultra-high dose rates. FC measurements with cyclotron currents up to 800 nA (dose rates of up to approximately 1000 Gy s-1) show that the FC is indeed dose rate independent. Then, the FC is applied to commission the primary gantry monitor for high dose rates. Finally, short-term reproducibility of the monitor calibration is quantified within single days, showing a standard deviation of 0.1% (one sigma). In conclusion, the FC is a promising, dose rate independent tool for dosimetry up to ultra-high dose rates. Caution is however necessary when using a FC without magnetic field, as a guard ring with high voltage alone can introduce an energy dependent signal offset

Perioperative hematoma with subcutaneous ICD implantation: Impact of anticoagulation and antiplatelet therapies

BackgroundThe safety of perioperative anticoagulation (AC) and antiplatelet (AP) therapy with subcutaneous implantable cardioverter‐defibrillator (S‐ICD) implantation is unknown. The purpose of this study was to identify the risk factors associated with hematoma complicating S‐ICD implantation.MethodsRecords were retrospectively reviewed from 200 consecutive patients undergoing S‐ICD implantation at two academic medical centers. A hematoma was defined as a device site blood accumulation requiring surgical evacuation, extended hospital stay, or transfusion.ResultsAmong 200 patients undergoing S‐ICD implantation (age 49 ± 17 years, 67% men), 10 patients (5%) had a hematoma, which required evacuation in six patients (3%). Warfarin was bridged or uninterrupted in 12 and 13 patients, respectively (6% and 6.5%). Four of 12 patients with warfarin and bridging AC (33%) and two of 13 patients with uninterrupted warfarin (15%) developed a hematoma. Neither of the two patients with uninterrupted DOAC had a hematoma. No patients on interrupted AC without bridging (n = 26, 13 with warfarin, 13 with DOAC) developed a hematoma. A hematoma was also more likely with the use of clopidogrel (n = 4/10 vs 10/190, 40% vs 5.3%, P < 0.0001) in combination with aspirin in 12/14 patients. Any bridging AC (odds ratio [OR] 10.3, 1.8–60.8, P = 0.01), clopidogrel (OR 10.0, 1.7–57.7, P = 0.01), and uninterrupted warfarin without bridging (OR 11.1, 1.7–74.3, P = 0.013) were independently associated with hematoma formation.ConclusionAC and/or AP therapy with clopidogrel appears to increase the risk for hematoma following S‐ICD implantation. Interruption of AC without bridging should be considered when it is an acceptable risk to hold AC.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145383/1/pace13349_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/145383/2/pace13349.pd