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John E. Smith

Other affiliations: Bandung Institute of Technology
Bio: John E. Smith is an academic researcher from University of Strathclyde. The author has contributed to research in topics: Aflatoxin & Aspergillus flavus. The author has an hindex of 33, co-authored 115 publications receiving 2911 citations. Previous affiliations of John E. Smith include Bandung Institute of Technology.


Papers
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TL;DR: Purified bioactive compounds derived from medicinal mushrooms are a potentially important new source of anticancer agents; their assimilation into Western drug discovery programs and clinical trials also provides a framework for the study and use of other traditional medicines.
Abstract: Modern medical practice relies heavily on the use of highly purified pharmaceutical compounds whose purity can be easily assessed and whose pharmaceutical activity and toxicity show clear structure-function relationships. In contrast, many herbal medicines contain mixtures of natural compounds that have not undergone detailed chemical analyses and whose mechanism of action is not known. Traditional folk medicine and ethno-pharmacology coupled to bioprospecting have been an important source of many anticancer agents as well as other medicines. With the current decline in the number of new molecular entities from the pharmaceutical industry, novel anticancer agents are being sought from traditional medicine. As the example of medicinal mushrooms demonstrates, however, translating traditional Eastern practices into acceptable evidence-based Western therapies is difficult. Different manufacturing standards, criteria of purity, and under-powered clinical trials make assessment of efficacy and toxicity by Western standards of clinical evidence difficult. Purified bioactive compounds derived from medicinal mushrooms are a potentially important new source of anticancer agents; their assimilation into Western drug discovery programs and clinical trials also provides a framework for the study and use of other traditional medicines.

248 citations

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TL;DR: Methods of large-scale cultivation by solid substrate and liquid culture fermentations are briefly described, and many of the bioactive molecules identified are reviewed.
Abstract: Historically, medicinal mushrooms (basidiomycetes) have been shown to have profound health promoting benefits and recent studies, which are reviewed here, are now confirming their medical efficacy and identifying many of the bioactive molecules. Methods of large-scale cultivation by solid substrate and liquid culture fermentations are also briefly described.

202 citations

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TL;DR: The impact of mycotoxins on human and animal health is now increasingly recognised and establishing a causal relationship between mycotoxin exposure and human disease is complicated by uncertainties associated with human epidemiological studies.
Abstract: The impact of mycotoxins on human and animal health is now increasingly recognised. Mycotoxin entry to the human and animal dietary systems is mainly by ingestion but increasing evidence also points at entry by inhalation. Mycotoxins exhibit a wide array of biological effects and individual mycotoxins can be mutagenic, carcinogenic, embryotoxic, teratogenic, or oestrogenic. Average levels of ingestion of currently known mycotoxins in most EEC countries are rather low. Little is known about the consequences to humans of such mycotoxin intakes. Establishing a causal relationship between mycotoxin exposure and human disease is complicated by uncertainties associated with human epidemiological studies. Analysis of mycotoxin adducts in human populations can act as a surrogate for human genotoxicity. Mycotoxins can also be immunosuppressive and appear to involve cellular immune phenomena and non-specific humoral factors associated wtih immunity. © 1995 Wiley-Liss, Inc.

147 citations

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TL;DR: There was a complex interaction among temperature, water activity, incubation period, and substrate on coproduction of aflatoxins and cyclopiazonic acid by an isolate of Aspergillus flavus and this influenced the relative concentrations of the mycotoxins produced.
Abstract: An experiment with a full factorial design was used to study the effects of and interactions among temperature, water activity (a(infw)), incubation period, and substrate on coproduction of aflatoxins (AF) and cyclopiazonic acid (CPA) by an isolate of Aspergillus flavus. Analysis of variance showed that there was a complex interaction among all of these factors and that this influenced the relative concentrations of the mycotoxins produced. The optimum temperatures for the production of AF and CPA were 30(deg)C and 25(deg)C, respectively. Both mycotoxins were maximally produced (0.306 to 0.330 (mu)g of AF(middot)ml of medium(sup-1), 4.040 to 6.256 (mu)g of CPA(middot)ml of medium(sup-1)) at an a(infw) of 0.996 and after 15 days of incubation. No AF were produced in either yeast extract agar or Czapek yeast autolysate agar medium at an a(infw) of 0.90 at 20 or 37(deg)C after 15 days (minimum conditions), while 0.077 to 0.439 (mu)g of CPA(middot)ml of medium(sup-1) was produced under the same conditions. Yeast extract agar favored maximum AF production, and Czapek yeast autolysate agar favored maximum CPA production.

112 citations

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TL;DR: The ability of Aspergillus niger conidia to produce conidiophores after germination in shaken culture at 30° was stimulated by the inclusion of glutamate in the medium and viable conidia were produced.
Abstract: SUMMARY: The ability of Aspergillus niger conidia to produce conidiophores after germination in shaken culture at 30° was stimulated by the inclusion of glutamate in the medium. Incubation of the conidia at 35° to 41° increased swelling of the conidia and also the proportion which produced conidiophores. Although conidiophore initiation was stimulated at temperatures between 35° and 41°, maturation was poor and optimum conidiation was obtained by incubation at these temperatures followed by 30°. Conidiophore formation from conidia required a prior period of spore metabolism and at temperatures between 30° and 41° did not occur until several hours after germination. Direct conidiophore production from conidia in the complete absence of vegetative growth was achieved by incubation of the conidia at 44° (which allows only swelling) for a prolonged period (48 h.) followed by 30°. Although vegetative growth was absent the conidiophores were similar to, but smaller than, normal subaerial conidiophores and viable conidia were produced. These conidia differed from subaerial spores in lacking the dark pigmented spore coat.

110 citations


Cited by
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TL;DR: Mycotoxins have various acute and chronic effects on humans and animals depending on species and susceptibility of an animal within a species, and ruminants have, however, generally been more resistant to the adverse effects of mycotoxin.

1,542 citations

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TL;DR: The current status of the technology for ethanol production from softwood is reviewed, with focus on hemicellulose and cellulose hydrolysis, which is the major problem in the overall process.
Abstract: Ethanol produced from various lignocellulosic materials such as wood, agricultural and forest residues has the potential to be a valuable substitute for, or complement to, gasoline One of the major resources in the Northern hemisphere is softwood This paper reviews the current status of the technology for ethanol production from softwood, with focus on hemicellulose and cellulose hydrolysis, which is the major problem in the overall process Other issues of importance, eg overall process configurations and process economics are also considered

1,153 citations

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TL;DR: Immobilization of oxidative enzymes on porous ceramic supports or resins did not adversely affect their stability and showed a good potential for degradation of environment persistent aromatics.
Abstract: A number of oxidative enzymes from bacteria, fungi and plants have been reported to play an important role in numerous waste treatment applications. Peroxidases and/or phenoloxidases can act on specific recalcitrant pollutants by precipitation or transforming to other products and permitting a better final treatment of the waste. Improvement in the useful life and thereby a reduction in treatment cost has been accomplished through enzyme immobilization. Horseradish peroxidase, lignin peroxidase and manganese peroxidase mineralize a variety of recalcitrant aromatic compounds. Immobilization of these enzymes on porous ceramic supports or resins did not adversely affect their stability and showed a good potential for degradation of environment persistent aromatics. Tyrosinase, which catalyzes the hydroxylation of phenols and dehydrogenation of o-diphenols, in an immobilized form exerted an excellent phenol removal. Laccase is capable of eliminating the phenols through polymerization process, however, the presence of mediator such as ABTS and HBT degraded phenol by oxidative process. Many applications with oxidative enzymes and plant materials in effluent as in soil remediation will be discussed.

894 citations

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TL;DR: This review presents an overview of various aspects of biological pretreatment, enzymes involved in the process, parameters affecting biological pret treatment as well as future perspectives.

865 citations

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TL;DR: Critical areas for future DON research include molecular mechanisms underlying toxicity, sensitivity of human cells/tissues relative to other species, emetic effects in primates, epidemiological association with gastroenteritis and chronic disease in humans, and surveillance in cereal crops worldwide.
Abstract: Deoxynivalenol (DON) is a mycotoxin that commonly contaminates cereal-based foods worldwide. At the molecular level, DON disrupts normal cell function by inhibiting protein synthesis via binding to the ribosome and by activating critical cellular kinases involved in signal transduction related to proliferation, differentiation, and apoptosis. Relative to toxicity, there are marked species differences, with the pig being most sensitive to DON, followed by rodent > dog > cat > poultry > ruminants. The physiologic parameter that is most sensitive to low-level DON exposure is the emetic response, with as little as 0.05 to 0.1 mg/kg body weight (bw) inducing vomiting in swine and dogs. Chinese epidemiological studies suggest that DON may also produce emetic effects in humans. With respect to chronic effects, growth (anorexia and decreased nutritional efficiency), immune function, (enhancement and suppression), and reproduction (reduced litter size) are also adversely affected by DON in animals, whereas incidence of neoplasia is not affected. When hazard evaluations were conducted using existing chronic toxicity data and standard safety factors employed for anthropogenic additives/contaminants in foods, tolerable daily intakes (TDIs) ranging from 1 to 5 microg/kg bw have been generated. Given that critical data gaps still exist regarding the potential health effects of DON, additional research is needed to improve capacity for assessing adverse health effects of this mycotoxin. Critical areas for future DON research include molecular mechanisms underlying toxicity, sensitivity of human cells/tissues relative to other species, emetic effects in primates, epidemiological association with gastroenteritis and chronic disease in humans, and surveillance in cereal crops worldwide.

824 citations