Effects of some thermal, chemical and mechanical treatments on lipase activity in Shammi goat milk

The effects of heating (20, 37 or 50 °C), cooling (5 °C), pasteurisation (71 °C for 15 s), boiling (100 °C), agitation (5 or 10 min), pH (acid or alkaline), and addition of chemicals such as silver and lead nitrates, copper sulphate and sodium chloride on lipase activity in Shammi goat milk were studied. There were non-significant differences (P < 0.01) in chemical composition between Shammi goat milk and Arabi cow milk. Lipase activity in Shammi goat milk was non-significantly (P < 0.01) lower than in Arabi cow milk. Lipase activity in milk of Shammi goats and Arabi cows was reduced when the milk was subjected to heating, cooling, pasteurisation, boiling, or when chemicals or acid was added, whereas in agitated and alkaline milk, the lipase activity was increased. The increase following agitation was greater after 10 min than 5 min. It can be concluded that heating, pasteurising, boiling, cooling, addition of certain chemicals and acidity are means by which lipase activity in milk can be reduced.     

Biotechnology-a sustainable alternative for chemical industry

This review outlines the current and emerging applications of biotechnology, particularly in the production and processing of chemicals, for sustainable development. Biotechnology is “the application of scientific and engineering principles to the processing of materials by biological agents”. Some of the defining technologies of modern biotechnology include genetic engineering; culture of recombinant microorganisms, cells of animals and plants; metabolic engineering; hybridoma technology; bioelectronics; nanobiotechnology; protein engineering; transgenic animals and plants; tissue and organ engineering; immunological assays; genomics and proteomics; bioseparations and bioreactor technologies. Environmental and economic benefits that biotechnology can offer in manufacturing, monitoring and waste management are highlighted. These benefits include the following: greatly reduced dependence on nonrenewable fuels and other resources; reduced potential for pollution of industrial processes and products; ability to safely destroy accumulated pollutants for remediation of the environment; improved economics of production; and sustainable production of existing and novel products.     

Isometric and Eccentric Force Generation Assessment of Skeletal Muscles Isolated from Murine Models of Muscular Dystrophies

Critical to the evaluation of potential therapeutics for muscular disease are sensitive and reproducible physiological assessments of muscle function. Because many pre-clinical trials rely on mouse models for these diseases, isolated muscle function has become one of the standards for Go/NoGo decisions in moving drug candidates forward into patients. We will demonstrate the preparation of the extensor digitorum longus (EDL) and diaphragm muscles for functional testing, which are the predominant muscles utilized for these studies. The EDL muscle geometry is ideal for isolated muscle preparations, with two easily accessible tendons, and a small size that can be supported by superfusion in a bath. The diaphragm exhibits profound progressive pathology in dystrophic animals, and can serve as a platform for evaluating many potential therapies countering fibrosis, and promoting myofiber stability. Protocols for routine testing, including isometric and eccentric contractions, will be shown. Isometric force provides assessment of strength, and eccentric contractions help to evaluate sarcolemma stability, which is disrupted in many types of muscular dystrophies. Comparisons of the expected results between muscles from wildtype and dystrophic muscles will also be provided. These measures can complement morphological and biochemical measurements of tissue homeostasis, as well as whole animal assessments of muscle function.     

Anticancer Metal Complexes: Synthesis and Cytotoxicity Evaluation by the MTT Assay

Titanium (IV) and vanadium (V) complexes are highly potent anticancer agents. A challenge in their synthesis refers to their hydrolytic instability; therefore their preparation should be conducted under an inert atmosphere. Evaluation of the anticancer activity of these complexes can be achieved by the MTT assay.The MTT assay is a colorimetric viability assay based on enzymatic reduction of the MTT molecule to formazan when it is exposed to viable cells. The outcome of the reduction is a color change of the MTT molecule. Absorbance measurements relative to a control determine the percentage of remaining viable cancer cells following their treatment with varying concentrations of a tested compound, which is translated to the compound anticancer activity and its IC₅₀ values. The MTT assay is widely common in cytotoxicity studies due to its accuracy, rapidity, and relative simplicity.Herein we present a detailed protocol for the synthesis of air sensitive metal based drugs and cell viability measurements, including preparation of the cell plates, incubation of the compounds with the cells, viability measurements using the MTT assay, and determination of IC₅₀ values.     

化学腐蚀性组织工程皮肤检测模型的构建

利用组织工程学方法,以牛I型胶原为支架,人表皮角质形成细胞和真皮成纤维细胞为细胞来源,构建化学腐蚀性检测用组织工程皮肤模型。选用欧洲替代方法验证中心(the Interagency Coordinating Committee on the Validation of Alternative Methods,ICCVAM)制定的体外测试化学品腐蚀性最小执行标准中的8种化学品为检测物质。在检测实验中,8种化学品(固体10mg、液体25μl)分3min、1h局部接触组织工程皮肤模型表面,MTT方法测定细胞活力,相对细胞活力值作为判定腐蚀性的标准。结果表明,构建的组织工程皮肤检测模型结构完整,含有基底层、棘层、颗粒层和角质层,能准确判断7种化学品的腐蚀性。构建的组织工程皮肤模型可以作为检测工具用于化学品腐蚀性的检测。     

Synthesis of Hypervalent Iodonium Alkynyl Triflates for the Application of Generating Cyanocarbenes

The procedures described in this article involve the synthesis and isolation of hypervalent iodonium alkynyl triflates (HIATs) and their subsequent reactions with azides to form cyanocarbene intermediates. The synthesis of hypervalent iodonium alkynyl triflates can be facile, but difficulties stem from their isolation and reactivity. In particular, the necessity to use filtration under inert atmosphere at -45 °C for some HIATs requires special care and equipment. Once isolated, the compounds can be stored and used in reactions with azides to form cyanocarbene intermediates. The evidence for cyanocarbene generation is shown by visible extrusion of dinitrogen as well as the characterization of products that occur from O-H insertion, sulfoxide complexation, and cyclopropanation. A side reaction of the cyanocarbene formation is the generation of a vinylidene-carbene and the conditions to control this process are discussed. There is also potential to form a hypervalent iodonium alkenyl triflate and the means of isolation and control of its generation are provided. The O-H insertion reaction involves using a HIAT, sodium azide or tetrabutylammonium azide, and methanol as solvent/substrate. The sulfoxide complexation reaction uses a HIAT, sodium azide or tetrabutylammonium azide, and dimethyl sulfoxide as solvent. The cyclopropanations can be performed with or without the use of solvent. The azide source must be tetrabutylammonium azide and the substrate shown is styrene.     

Exposure to polychlorinated biphenyls causes endothelial cell dysfunction

Environmental chemicals, such as polychlorinated biphenyls (PCBs), may be atherogenic by disrupting normal functions of the vascular endothelium. To investigate this hypothesis, porcine pulmonary artery-derived endothelial cells were exposed to 3,3′,4,4′-tetrachlorobiphenyl (PCB 77), 2,3,4,4′,5-pentachlorobiphenyl (PCB 114), or 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB 153) for up to 24 hours. These PCBs were selected for their varying binding avidities with the aryl hydrocarbon (Ah) receptor and differences in their induction of cytochrome P450. PCB 77 and PCB 114 significantly disrupted, in a dose-dependent manner, endothelial barrier function by allowing an increase in albumin transfer across endothelial monolayers. These PCBs also contributed markedly to cellular oxidative stress, as measured by 2,7-dichlorofluorescin (DCF) fluorescence and lipid hydroperoxides, and caused a significant increase in intracellular calcium ([Ca²⁺]_i) levels. Enhanced oxidative stress and [Ca²⁺]_i in PCB 77- and PCB 114-treated cells were accompanied by increased activity and content of cytochrome P450 1A and by a decrease in the vitamin E content in the culture medium. In contrast to the effects of PCB 77 and PCB 114, cell exposure to PCB 153 had no effect on cellular oxidation, [Ca²⁺]_i, or endothelial barrier function. These results suggest that certain PCBs may play a role in the development of atherosclerosis by causing endothelial cell dysfunction and a decrease in the barrier function of the vascular endothelium. It is possible that interaction of PCBs with the Ah receptor and activation of the cytochrome P450 1A subfamily are involved in this pathology. © 1995 John Wiley & Sons, Inc.     

What should and what can biotechnology contribute to chemical bulk production?

Abstract: In terms of the chemical industry most biotech products have a fine chemical or even speciality character. Nevertheless there is at least one striking example of a fermentation-derived bulk chemical, bio-ethanol, which provides an excellent case study of the economic and technological prerequisites which biotechnology has to attain as a supplier to the chemical marketplace. The competitive position of existing and new products produced from renewable resources through biotechnological conversion methods will depend on its market acceptance - overall environmental compatibility and cost performance. In order to provide significant contributions to chemical bulk production beyond 2000, biotechnologists and chemical engineers are requested to search for new products, new processes to existing products and new technologies to overcome present cost constraints in fermentation, bioconversion and downstream processing.     

Appraisal of prospective bivalve immunomarkers

Worldwide concern over threats to natural resources and public health has led to increased efforts to monitor and assess environmental conditions. This has stimulated the need for development and application of select biological and ecological measurements, or indicators, that are responsive to environmental stress. Measures of bivalve mollusc defence activities, such as haemocyte density, phagocytic activity, locomotion and production of cytotoxic molecules; and haemolymph constituents, such as agglutinins and lysozyme, have potential as indicators and appear to be responsive to xenobiotic chemical insults in the aquatic environment. However, basic research on the relevance of these measurements in inferring resistance to disease or enhanced survival is currently insufficient, reducing their value as potential biomarkers to address environmental objectives. In addition, variation in defence activities caused by seasonal temperature and reproductive cycling, salinity changes, nutritional status, diseases and parasites, and genetic stocks is high and may limit applicability of bivalve defence-related measurements as indicators. This review examines these sources of variability and their possible implications for interpreting changes in bivalve defence activity as an indicator of stress. Examples of contaminant-induced changes in bivalve defence functions are described.     

Non-conventional hosts for the production of fuels and chemicals

Biotechnology offers a green alternative for the production of fuels and chemicals using microbes. Although traditional model hosts such as Escherichia coli and Saccharomyces cerevisiae have been widely studied and used, they may not be the best hosts for industrial application. In this review, we explore recent advances in the use of nonconventional hosts for the production of a variety of fuel, cosmetics, perfumes, food, and pharmaceuticals. Specifically, we highlight twenty-seven popular molecules with a special focus on recent progress and metabolic engineering strategies to enable improved production of fuels and chemicals. These examples demonstrate the promise of nonconventional host engineering.