Optimization of microwave-assisted transesterification of dry algal biomass using response surface methodology

The effect of microwave irradiation on the simultaneous extraction and transesterification (in situ transesterification) of dry algal biomass to biodiesel was investigated. A high degree of oil/lipid extraction from dry algal biomass and an efficient conversion of the oils/lipids to biodiesel were demonstrated in a set of well-designed experimental runs. A response surface methodology (RSM) was used to analyze the influence of the process variables (dry algae to methanol (wt/vol) ratio, catalyst concentration, and reaction time) on the fatty acid methyl ester conversion. Based on the experimental results and RSM analysis, the optimal conditions for this process were determined as: dry algae to methanol (wt/vol) ratio of around 1:12, catalyst concentration about 2 wt.%, and reaction time of 4 min. The algal biodiesel samples were analyzed with GC-MS and thin layer chromatography (TLC) methods. Transmission electron microscopy (TEM) images of the algal biomass samples before and after the extraction/transesterification reaction are also presented.     

Bayesian geostatistics in health cartography: the perspective of malaria

Maps of parasite prevalences and other aspects of infectious diseases that vary in space are widely used in parasitology. However, spatial parasitological datasets rarely, if ever, have sufficient coverage to allow exact determination of such maps. Bayesian geostatistics (BG) is a method for finding a large sample of maps that can explain a dataset, in which maps that do a better job of explaining the data are more likely to be represented. This sample represents the knowledge that the analyst has gained from the data about the unknown true map. BG provides a conceptually simple way to convert these samples to predictions of features of the unknown map, for example regional averages. These predictions account for each map in the sample, yielding an appropriate level of predictive precision.     

Expression and Purification of Isotopically Enriched MHC Binding Immunogenic Peptides for NMR Studies

Peptides are important naturally occurring ligands of MHC molecules. X-ray crystallographic studies have enabled extensive characterization of such peptide ligands. Yet structural and dynamic changes of these peptides in the MHC bound state are not well understood. These conformational transitions are key to understanding the function of MHC molecules and for the development of peptide-based therapeutics. Employing NMR for such studies can fill this gap but it requires the availability of peptides labeled with NMR-active nuclei. Here we report production of nine-mer MHC-binding peptides for use in high resolution NMR studies. The method utilizes a fusion protein approach of attaching the peptide to an easily expressed bacterial protein. The fusion protein construct design allows for rapid purification of the fusion protein and avoids chemical modification of the peptide as a result of the cleavage reaction. The methods developed here allow for rapid cloning of additional MHC binding peptides without significant molecular biology effort. 8?C10 mg of mature freeze dried peptides can be obtained from 1 liter of minimal media, sufficient for NMR experimentation. Six uniformly ¹⁵N-labeled peptides have been successfully expressed in bacteria and NMR spectra with the expected number of well-resolved signals were recorded. The results obtained here will make peptide-MHC complexes amenable to structural analysis which has not been possible previously.     

Biomedical cloud computing with Amazon Web Services

In this overview to biomedical computing in the cloud, we discussed two primary ways to use the cloud (a single instance or cluster), provided a detailed example using NGS mapping, and highlighted the associated costs. While many users new to the cloud may assume that entry is as straightforward as uploading an application and selecting an instance type and storage options, we illustrated that there is substantial up-front effort required before an application can make full use of the cloud's vast resources. Our intention was to provide a set of best practices and to illustrate how those apply to a typical application pipeline for biomedical informatics, but also general enough for extrapolation to other types of computational problems. Our mapping example was intended to illustrate how to develop a scalable project and not to compare and contrast alignment algorithms for read mapping and genome assembly. Indeed, with a newer aligner such as Bowtie, it is possible to map the entire African genome using one m2.2xlarge instance in 48 hours for a total cost of approximately $48 in computation time. In our example, we were not concerned with data transfer rates, which are heavily influenced by the amount of available bandwidth, connection latency, and network availability. When transferring large amounts of data to the cloud, bandwidth limitations can be a major bottleneck, and in some cases it is more efficient to simply mail a storage device containing the data to AWS (http://aws.amazon.com/importexport/). More information about cloud computing, detailed cost analysis, and security can be found in references.     

Novel benzyl-substituted N-heterocyclic carbene-silver acetate complexes: synthesis, cytotoxicity and antibacterial studies

From the reaction of 1-methylimidazole (1a), 4,5-dichloro-1H-imidazole (1b(I)) and 1-methylbenzimidazole (1c) with p-cyanobenzyl bromide (2a), non-symmetrically substituted N-heterocyclic carbene (NHC) [(3a-c)] precursors, 5,6-dimethyl-1H-benzimidazole (1d) and 4,5-diphenyl-1H-imidazole (1e) with p-cyanobenzyl bromide (2a) and benzyl bromide (2b), symmetrically substituted N-heterocyclic carbene (NHC) [(3d-f)] precursors were synthesised. These NHC-precursors were then reacted with silver(i) acetate to yield the NHC-silver complexes (1-methyl-3-(4-cyanobenzyl)imidazole-2-ylidene)silver(i)acetate (4a), (4,5-dichloro-1-(4-cyanobenzyl)-3-methyl)imidazole-2-ylidene)silver(i)acetate (4b), (1-methyl-3-(4-cyanobenzyl)benzimidazole-2-ylidene)silver(i)acetate (4c), (1,3-bis(4-cyanobenzyl)5,6-dimethylbenzimidazole-2-ylidene) silver(i) acetate (4d), (1,3-dibenzyl-5,6-dimethylbenzimidazole-2-ylidene) silver(i) acetate (4e) and (1,3-dibenzyl-4,5-diphenylimidazol-2-ylidene) silver(i) acetate (4f) respectively. Three NHC-precursors 3c-e and four NHC-silver complexes 4b and 4d-f were characterised by single crystal X-ray diffraction. Preliminary in vitro antibacterial activity of the NHC-precursors and NHC-silver complexes was investigated against Gram-positive bacteria Staphylococcus aureus, and Gram-negative bacteria Escherichia coli using the qualitative Kirby-Bauer disk-diffusion method. NHC-silver complexes have shown very high antibacterial activity compared to the NHC-precursors. All six NHC-silver complexes were tested for their cytotoxicity through MTT based in vitro tests on the human renal-cancer cell line Caki-1 in order to determine their IC?? values. NHC-silver complexes 4a-f were found to have IC?? values of 6.2 (±1.0), 7.7 (±1.6), 1.2 (±0.6), 10.8 (±1.9), 24.2 (±1.8) and 13.6 (±1.0) μM, respectively. These values represent improved cytotoxicity against Caki-1, most notably for 4c, which is a three times more cytotoxic than cisplatin (IC?? value = 3.3 μM) itself.     

PSGL-1 derived from human neutrophils is a high-efficiency ligand for endothelium-expressed E-selectin under flow

P-selectin glycoprotein ligand-1 (PSGL-1) has been proposed as an important tethering ligand for E-selectin and is expressed at a modest level on human leukocytes. Sialyl Lewis x (sLe^x)-like glycans bind to E-selectin and are expressed at a relatively high level on circulating leukocytes. It is unclear whether PSGL-1 has unique biochemical attributes that contribute to its role as an E-selectin ligand. To probe this issue, we conjugated microspheres with either sLe^x or PSGL-1 purified from myeloid cells (neutrophils and HL-60) and compared their adhesion to endothelial expressed E-selectin under defined shear conditions. We found that both sLe^x and PSGL-1 microspheres adhere to 4 h of IL-1-activated human umbilical vein endothelial cells predominantly through E-selectin. Analysis of the adhesion revealed that the rate of initial tethering of the PSGL-1 microspheres to E-selectin was significantly greater than the rate of initial tethering of the sLe^x microspheres despite the fact that the sLe^x microspheres tested had higher ligand densities than the PSGL-1 microspheres. We also found that pretreatment of the PSGL-1 or sLe^x microspheres with HECA-452 had no significant effect on initial tethering to E-selectin. These results support the hypotheses that 1) PSGL-1 is a high-efficiency tethering ligand for E-selectin, 2) ligand biochemistry can significantly influence initial tethering to E-selectin, and 3) PSGL-1 tethering to E-selectin can occur via non-HECA-452 reactive epitopes. adhesion; leukocyte; inflammation     

Cast titanium overlay denture for a geriatric patient with a reduced vertical dimension

An older patient reporting to the dental surgery for his/her dental treatment is becoming a common occurrence. Improved oral hygiene has meant that teeth are retained for a longer time, along with the potential problems of attrition, decreased vertical dimension, temporomandibular joint discomfort/strain, and poor aesthetics. The case in question is that of a 65-year-old male patient who had severe attrition in the lower arch, temporomandibular joint pain and reduced vertical dimension. The maxillary arch had previously been restored with a fixed partial prosthesis. For restoration of the lower teeth, a removable cast titanium overlay denture was fabricated incorporating an increased vertical dimension. Porcelain facings were placed to restore the aesthetics of the anterior teeth. The titanium was cast in a semi-automatic electric arc, pressure type casting machine. A titanium overlay denture with porcelain facing on the anterior teeth may provide a means of restoring a patient's concerns regarding aesthetics and function.