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PubMed2004

Adsorption behavior of heavy metals on biomaterials.

We have investigated adsorption of Cd(II) and Pb(II) at pH 2-6.7 onto the biomaterials chitosan, coffee, green tea, tea, yuzu, aloe, and Japanese coarse tea, and onto the inorganic adsorbents, activated carbon and zeolite. High adsorptive capabilities were observed for all of the biomaterials at pH 4 and 6.7. In the adsorption of Cd(II), blend coffee, tea, green tea, and coarse tea have comparable loading capacities to activated carbon and zeolite. Although activated carbon, zeolite, and chitosan are utilized in a variety of fields such as wastewater treatment, chemical and metallurgical engineering, and analytical chemistry, these adsorbents are costly. On the other hand, processing of the test biomaterials was inexpensive, and all the biomaterials except for chitosan were able to adsorb large amounts of Pb(II) and Cd(II) ions after a convenient pretreatment of washing with water followed by drying. The high adsorption capability of the biomaterials prepared from plant materials is promising in the development of a novel, low-cost adsorbent. From these results, it is concluded that heavy metal removal using biomaterials would be an effective method for the economic treatment of wastewater. The proposed adsorption method was applied to the determination of amounts of Cd(II) and Pb(II) in water samples.

Adsorption↗
PubMed2001

Nanoparticles as structural and functional units in surface-confined architectures.

The nanoscale engineering of functional chemical assemblies has attracted recent research effort to provide dense information storage, miniaturized sensors, efficient energy conversion, light-harvesting, and mechanical motion. Functional nanoparticles exhibiting unique photonic, electronic and catalytic properties provide invaluable building blocks for such nanoengineered architectures. Metal nanoparticle arrays crosslinked by molecular receptor units on electrodes act as selective sensing interfaces with controlled porosity and tunable sensitivity. Photosensitizer/electron-acceptor bridged arrays of Au-nanoparticles on conductive supports act as photoelectrochemically active electrodes. Semiconductor nanoparticle composites on surfaces act as efficient light collecting systems, and nanoengineered semiconductor 'core-shell' nanocrystal assemblies reveal enhanced photoelectrochemical performance due to effective charge separation. Layered metal and semiconductor nanoparticle arrays crosslinked by nucleic acids find applications in the optical, electronic and photoelectrochemical detection of DNA. Metal and semiconductor nanoparticles assembled on DNA templates may be used to generate complex electronic circuitry. Nanoparticles incorporated in hydrogel matrices yield new composite materials with novel magnetic, optical and electronic properties.

Journal Article↗
PubMed2006

Progress towards the easier use of P450 enzymes.

The cytochrome P450 enzymes (P450s or CYPs) form a large family of heme proteins involved in drug metabolism and in the biosynthesis of steroids, lipids, vitamins and natural products. Their remarkable ability to catalyze the insertion of oxygen into non-activated C-H bonds has attracted the interest of chemists for several decades. Very few chemical methods exist that directly hydroxylate aliphatic or aromatic C-H bonds, and most of them are not selective or of limited scope. Biocatalysts such as P450s represent a promising alternative: however, their applications have been limited by substrate specificity, low activity, poor stability and the need for cofactors. This review covers the attempts to overcome these limitations using approaches such as mutagenesis, chemical modifications, conditions engineering and immobilization.

Bacterial Proteins↗
PubMed2002

C1s, the protease messenger of C1. Structure, function and physiological significance.

C1s is the modular serine protease, which executes the catalytic function of the C1 complex: the cleavage of C4 and C2. Like other complement serine proteases C1s has restricted substrate specificity and it is engaged into specific interactions with other subcomponents of the complement system. There has been a rapid progress in determining the 3D structure of complement serine proteases and in revealing the role of the individual domains in the protein-protein interaction properties. In this review we summarize recent findings on the structure of C1s, and on the mechanism of action of this protease. The results obtained by genetic engineering, physico-chemical and functional studies are reviewed. The physiological relevance of the proteolytic action of C1s and its possible implications in health and disease will also be discussed.

Animals↗
PubMedDate not supplied

A hierarchical approach to coding chemical, biological and pharmaceutical substances.

This hierarchical coding system is designed to classify substances into successively subordinate categories on the basis of chemical, physical and biological properties. Although initially developed for occupational cancer epidemiological studies, it is general in nature and can be used for other purposes where a systematic approach is needed to catalogue or analyze large numbers of substances and/or physical properties. The coding system incorporates a multi level approach, where substances can be coded both on the basis of function and composition. On the first level, a three digit code is assigned to each substance to indicate its primary use in the occupational environment (e.g. pesticide, catalyst, adhesive). Substances can then be coded using a ten digit code to indicate structure and composition (e.g. organic molecule, biomolecule, pharmaceutical). Depending on the complexity required, analysis can incorporate the three digit code, ten digit code, or a combination of both. The approach to coding both chemical and biological agents is modeled in part after conventional approaches used by the International Union of Pure and Applied Chemists (IUPAC) and the International Union of Biochemists (IUB). Development of the coding system was initiated in the 1980's in response to a need for a system allowing analysis of individual agents as well classes or groups of substances. The project was undertaken as a collaborative venture between the BC Cancer Agency, Cancer Control Research program (then Division of Epidemiology) and the Department of Chemical and Biological Engineering at the University of British Columbia.

Drug-Related Side Effects and Adverse Reactions↗
PubMed1996

Association of complementary fragments and the elucidation of protein folding pathways.

Natural or engineered sites for chemical cleavage can be used to generate complementary fragments of well characterized proteins. The peptide fragments represent a unique tool for studying early events in protein folding, since these are usually the most inaccessible to the experimentalist. Analysis of the isolated fragments in non-denaturing conditions together with the determination of the structure of the folded non-covalent complexes and, most importantly, the kinetic analysis of the resulting second-order association/folding reaction can give a more complete picture of a folding pathway. The contribution of fragments to the understanding of some well characterized protein folding pathways is discussed.

Bacterial Proteins↗
PubMed1992

Membrane topology of the mammalian P450 cytochromes.

The membrane topology of the mammalian P450 cytochromes has been studied intensively by computational approaches, proteolysis, chemical modification, genetic engineering, and immunochemistry. Initial results for the cytochromes of the endoplasmic reticulum appeared to indicate a polytopic, four to eight transmembrane anchor model with an active site buried in the membrane. However, recent findings show that the microsomal P450s are bound to the endoplasmic reticulum by only one or two transmembrane peptides located at the NH2-terminal end, and that the active site is part of a large cytoplasmic domain that may have one or two additional peripheral membrane contacts. The membrane-bound state is viewed as rather rigid, and the plane of the heme lies between perpendicular and parallel to the plane of the endoplasmic reticulum. The mitochondrial P450 cytochromes lack a hydrophobic NH2 terminus in the mature form, and thus differ from the microsomal isozymes in this significant way. However, although the exact topology of cytochrome P450 in the inner mitochondrial membrane remains to be elucidated, certain features are clearly comparable to those of microsomal P450. Therefore, the membrane topology of the P450 gene superfamily may follow a similar pattern.

Animals↗
PubMed2000

Universal scaling of wave propagation failure in arrays of coupled nonlinear cells

We study the onset of the propagation failure of wave fronts in systems of coupled cells. We introduce a new method to analyze the scaling of the critical external field at which fronts cease to propagate, as a function of intercellular coupling. We find the universal scaling of the field throughout the range of couplings and show that the field becomes exponentially small for large couplings. Our method is generic and applicable to a wide class of cellular dynamics in chemical, biological, and engineering systems. We confirm our results by direct numerical simulations.

Journal Article↗
PubMed1997

Spin doctors: new innovations for centrifugal apheresis.

The preparation of plasma from blood has a long history dating back to the early 1900s when the concept of blood washing replaced the traditional blood letting. Over the next 57 years landmark discoveries such as centrifugal and membrane filtration systems led to different and rapid plasma, solute, and cell separation. These were not singular events but rather events influenced by the converging chemical, physiological, and engineering advances that have characterized the latter half of the 20th century. These events have led to entire new fields of biomedical research. The biotechnology for on-line plasma separation and plasma treatment has opened a new era, expanding the application of extracorporeal technology to modern therapeutic medicine. The association of biochemical or cellular abnormalities with various disease states provides the rationale for therapeutic plasma exchange (the removal of large amounts of patient's plasma, alone or with replacement with crystalloid) and therapeutic cytopheresis (removal of cellular elements). The purpose of this review is to provide a historical picture of the innovative ideas of the spin doctors and their devices, which predate the centrifugal blood and cell separators commonplace to any hospital or blood bank worldwide. The emphasis is to define the historical events and their impacts on the development of centrifugal devices and apheresis technologies.

Blood Component Removal↗
PubMed1990

The hyperthermophilic archaebacterium, Pyrococcus furiosus. Development of culturing protocols, perspectives on scaleup, and potential applications.

From this brief discussion, it is clear that there are many obstacles to overcome before hyperthermophilic archaebacteria will be an important aspect of biotechnology. Nevertheless, the prospects are intriguing. The nature of the environments that harbor these organisms and the consequent requirements for their controlled culture suggest that chemical and biochemical engineers can play an important role in elucidating their scientific and technological aspects.

Archaea↗
PubMed1991

Comparative inactivation of poliovirus type 3 and MS2 coliphage in demand-free phosphate buffer by using ozone.

MS2 coliphage (ATCC 15597-B1) has been proposed by the U.S. Environmental Protection Agency as a surrogate for enteric viruses to determine the engineering requirements of chemical disinfection systems on the basis of previous experience with chlorine. The objective of this study was to determine whether MS2 coliphage was a suitable indicator for the inactivation of enteric viruses when ozone disinfection systems were used. Bench-scale experiments were conducted in 2-liter-batch shrinking reactors containing ozone demand-free 0.05 M phosphate buffer (pH 6.9) at 22 degrees C. Ozone was added as a side stream from a concentrated stock solution. It was found that an ozone residual of less than 40 micrograms/liter at the end of 20 s inactivated greater than 99.99% of MS2 coliphage in the demand-free buffer. When MS2 was compared directly with poliovirus type 3 in paired experiments, 1.6 log units more inactivation was observed with MS2 coliphage than with poliovirus type 3. It was concluded that the use of MS2 coliphage as a surrogate organism for studies of enteric virus with ozone disinfection systems overestimated the inactivation of enteric viruses. It is recommended that the regulatory agencies evaluate their recommendations for using MS2 coliphage as an indicator of enteric viruses.

Buffers↗
PubMed2005

Enhanced trehalose production improves growth of Escherichia coli under osmotic stress.

The biosynthesis of trehalose has been previously shown to serve as an important osmoprotectant and stress protectant in Escherichia coli. Our results indicate that overproduction of trehalose (integrated lacI-Ptac-otsBA) above the level produced by the native regulatory system can be used to increase the growth of E. coli in M9-2% glucose medium at 37 degrees C to 41 degrees C and to increase growth at 37 degrees C in the presence of a variety of osmotic-stress agents (hexose sugars, inorganic salts, and pyruvate). Smaller improvements were noted with xylose and some fermentation products (ethanol and pyruvate). Based on these results, overproduction of trehalose may be a useful trait to include in biocatalysts engineered for commodity chemicals.

Escherichia coli K12↗
PubMed2004

Reversal of abnormal collagen production in Crohn's disease intestinal biopsies treated with regenerating agents.

BACKGROUND: Crohn's disease (CD) is characterised by inflammation, muscle layer overgrowth, and collagenous fibrosis of the intestinal tract, with no effective therapy against collagen accumulation. AIMS: We quantified production of collagen in resection specimens from normal and CD patients and investigated the effect of regenerating agents (RGTAs) on collagen production. RGTAs are chemically substituted dextrans engineered to mimic the growth factor protecting effects of heparan sulphates. RGTAs have been shown to enhance tissue repair in various in vivo models and to modulate in vitro collagen phenotype differentially according to their structure. PATIENTS: We studied intestinal biopsies from two groups of CD patients: treated with glucocorticoids (CD-GC group: 10 patients) or not treated (CD group: seven patients), and from seven control patients. METHODS: After 24 hours of ex vivo incubation with (3H) proline, collagen I, III, and V were extracted by pepsin and quantitatively separated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis. Biosynthesis of each collagen type was quantified on radiolabelled isolated collagen. RESULTS: Total intestinal collagen production in CD patients compared with controls was increased up to 3.5-fold overall (p<0.001). In particular, collagen III biosynthesis was enhanced by 6.2-fold (p<0.001) in CD patients. In the CD-GC group, collagen production abnormalities were less marked. RGTAs added to the incubation medium in the CD group decreased total collagen production by 50% and decreased collagen III synthesis by 76%. CONCLUSION: This finding offers a rationale for using RGTAs in the treatment of intestinal fibrosis in CD, thus opening up a potential new therapeutic field for this family of drugs.

Adult↗
PubMed1996

Selenocysteine.

Selenocysteine is recognized as the 21st amino acid in ribosome-mediated protein synthesis and its specific incorporation is directed by the UGA codon. Unique tRNAs that have complementary UCA anticodons are aminoacylated with serine, the seryl-tRNA is converted to selenocysteyl-tRNA and the latter binds specifically to a special elongation factor and is delivered to the ribosome. Recognition elements within the mRNAs are essential for translation of UGA as selenocysteine. A reactive oxygen-labile compound, selenophosphate, is the selenium donor required for synthesis of selenocysteyl-tRNA. Selenophosphate synthetase, which forms selenophosphate from selenide and ATP, is found in various prokaryotes, eukaryotes, and archaebacteria. The distribution and properties of selenocysteine-containing enzymes and proteins that have been discovered to date are discussed. Artificial selenoenzymes such as selenosubtilisin have been produced by chemical modification. Genetic engineering techniques also have been used to replace cysteine residues in proteins with selenocysteine. The mechanistic roles of selenocysteine residues in the glutathione peroxidase family of enzymes, the 5' deiodinases, formate dehydrogenases, glycine reductase, and a few hydrogenases are discussed. In some cases a marked decrease in catalytic activity of an enzyme is observed when a selenocysteine residue is replaced with cysteine. This substitution caused complete loss of glycine reductase selenoprotein A activity.

Catalysis↗
PubMed2005

Cancer incidence among male military and civil pilots and flight attendants: an analysis on published data.

Flight personnel are exposed to cosmic ionizing radiation, chemicals (fuel, jet engine exhausts, cabin air pollutants), electromagnetic fields from cockpit instruments, and disrupted sleep patterns. Only recently has cancer risk among these workers been investigated. With the aim of increasing the precision of risk estimates of cancer incidence, follow-up studies reporting a standardized incidence ratio for cancer among male flight attendants, civil and military pilots were obtained from online databases and analysed. A meta-analysis was performed by applying a random effect model, obtaining a meta-standardized incidence ratio (SIR), and 95% confidence interval (CI). In male cabin attendants, and civil and military pilots, meta-SIRs were 3.42 (CI = 1.94-6.06), 2.18 (1.69-2.80), 1.43 (1.09-1.87) for melanoma; and 7.46 (3.52-15.89), 1.88 (1.23-2.88), 1.80 (1.25-2.58) for other skin cancer, respectively. These tumors share as risk factors, ionizing radiation, recreational sun exposure and socioeconomic status. The meta-SIRs are not adjusted for confounding; the magnitude of risk for melanoma decreased when we corrected for socioeconomic status. In civil pilots, meta-SIR was 1.47 (1.06-2.05) for prostate cancer. Age (civil pilots are older than military pilots and cabin attendants) and disrupted sleep pattern (entailing hyposecretion of melatonin, which has been reported to suppress proliferative effects of androgen on prostate cancer cells) might be involved. In male cabin attendants, meta-SIR was 21.5 (2.25-205.8) for Kaposi's sarcoma and 2.49 (1.03-6.03) for non-Hodgkin's lymphoma. AIDS, which was the most frequent single cause of death in this occupational category, likely explains the excess of the latter two tumors.

Aircraft↗
PubMed2006

Virtual histology of transgenic mouse embryos for high-throughput phenotyping.

A bold new effort to disrupt every gene in the mouse genome necessitates systematic, interdisciplinary approaches to analyzing patterning defects in the mouse embryo. We present a novel, rapid, and inexpensive method for obtaining high-resolution virtual histology for phenotypic assessment of mouse embryos. Using osmium tetroxide to differentially stain tissues followed by volumetric X-ray computed tomography to image whole embryos, isometric resolutions of 27 mum or 8 mum were achieved with scan times of 2 h or 12 h, respectively, using mid-gestation E9.5-E12.5 embryos. The datasets generated by this method are immediately amenable to state-of-the-art computational methods of organ patterning analysis. This technique to assess embryo anatomy represents a significant improvement in resolution, time, and expense for the quantitative, three-dimensional analysis of developmental patterning defects attributed to genetically engineered mutations and chemically induced embryotoxicity.

Animals↗
PubMed2005

Modeling pancreatic cancer in animals to address specific hypotheses.

Multiple experimental approaches have been employed to study exocrine pancreatic cancer, including the use of animals as surrogates for the human disease. Animals have the advantage that they can be manipulated to address specific hypotheses regarding mechanisms underlying this disease. Implicit in this opportunity is the necessity to match the question being asked with an appropriate animal model. Several approaches to modeling pancreatic cancer have been established that involve animals. First, xenogeneic cell transplantation, generally into immunocompromised rodent subcutis or pancreas, allows examination of (1) the effect of host environment on human or rodent pancreatic cancer cells, (2) whether specific genetic changes in donor cells correlate with certain cancer cell behaviors, and (3) novel approaches to cancer therapy or imaging of tumor growth. Second, carcinogen administration, typically to hamster or rat, allows examination of whether specific genetic, biochemical, cellular, and tissue phenotypic changes, including progression to neoplasia, accompany exposure to a particular chemical. Third, genetically engineered animals, usually transgenic or gene targeted mice, allow examination of (1) whether genetic changes, including oncogene overexpression/mutation or tumor suppressor gene loss, can increase the risk for neoplastic progression, (2) whether specific genetic changes can cooperate during pancreatic carcinogenesis, and (3) how the genetic signature of a neoplasm correlates with particular biological aspects of tumor initiation and progression. Collectively, these experimental approaches permit detailed exploration of pancreatic cancer genetics and biology in the whole animal context, thereby mimicking the environment in which human disease occurs.

Adenocarcinoma↗
PubMed2006

An introduction to plant cell culture: Back to the future.

Plant cell, tissue, and organ culture is a set of techniques designed for the growth and multiplication of cells and tissues using nutrient solutions in an aseptic and controlled environment. This technology explores conditions that promote cell division and genetic reprogramming in in vitro conditions. Mainly developed in the early 1960s, plant tissue culture has turned into a standard procedure for modem biotechnology and today one can recognize five major areas where in vitro cell cultures are currently applied: large-scale propagation of elite materials, generation of genetic modified fertile individuals, as a model system for fundamental plant cell physiology aspects, preservation of endangered species, and metabolic engineering of fine chemicals. This chapter reviews the recent advances in such areas.

Cell Culture Techniques↗