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Biomedical subjects

A B Hanley

Publications and source records attributed to A B Hanley.

13 recordsLinked to original sources
PubMed2005

Acrylamide reduction in processed foods.

The discovery of the formation of acrylamide in fried and baked foods containing high levels of starch and the amino acid asparagine, prompted widespread concern. Both processed and home cooked foods are affected and this has led to the increased study of variations in cooking and processing conditions to minimize formation. While changes in cooking protocols have been in part successful, particularly when lower frying and baking temperatures are used, pretreatments to reduce levels of acrylamide by prevention of formation or acceleration of destruction have been investigated. In this study, a range of pretreatments of grilled potato were investigated and compared with surface washing to remove asparagine and reducing sugars. Synergies were observed between different treatments, and reductions of up to 40% were achieved in a non-optimized system.

Acrylamide↗
PubMed2001

Biomarkers in disease and health.

Biomarkers have considerable potential in aiding the understanding of the relationship between diet and disease or health. However, to assess the role, relevance and importance of biomarkers on a case by case basis it is essential to understand and prioritise the principal diet and health issues. In the majority of cases, dietary compounds are only weakly biologically active in the short term, have multiple targets and can be both beneficial and deleterious. This poses particular problems in determining the net effect of types of foods on health. In principle, a biomarker should be able to contribute to this debate by allowing the measurement of exposure and by acting as an indicator either of a deleterious or of an enhanced health effect prior to the final outcome. In this review, the examples chosen - cancer (stomach, colon/rectal, breast); coronary heart disease and osteoporosis - reflect three major diet-related disease issues. In each case the onset of the disease has a genetic determinant which may be exacerbated or delayed by diet. Perhaps the most important factor is that in each case the disease, once manifest, is difficult to influence in a positive way by diet alone. This then suggests that the emphasis for biomarker studies should focus on predictive biomarkers which can be used to help in the development of dietary strategies which will minimise the risk and be of greater benefit.

Biomarkers↗
PubMed1996

Analysis, separation, and bioassay of pyrrolizidine alkaloids from comfrey (Symphytum officinale).

Pyrrolizidine alkaloids have been linked to liver and lung cancers and a range of other deleterious effects. As with many natural toxicants, major problems arise in determining the effects of the different members of the class and the importance of various forms of ingestion. In this study we have investigated the levels of pyrrolizidine alkaloids in comfrey (Symphytum officinale), determined the levels in different parts of the plant and in herbal remedies, separated the alkaloids into two main groups--the principal parent alkaloids and the corresponding N-oxides--and, finally, carried out a simple bioassay based upon the mutagenic capability of the separated compounds in a human cell line. We conclude that the part of the plant ingested is important in terms of alkaloid challenge and that the effect of two of the major groups of alkaloids individually is different from that of alkaloids in the whole plant extract.

Base Sequence↗
PubMed1996

Metabolic activation of pyrrolizidine alkaloids by human, rat and avocado microsomes.

Two pyrrolizidine alkaloids and one pyrrolizidine alkaloid-N-oxide were incubated with microsomal preparations from humans, rat and avocado and the product profiles examined. The alkaloids were converted to dehydroretronecine, the putative toxic metabolite, by both rat and human microsomal preparations. In addition, alkaloid-N-oxides, the major detoxication products from pyrrolizidine alkaloids, were also formed. The pyrrolizidine alkaloid-N-oxide was converted to both dehydroretronecine and the parent alkaloid. This suggests that the toxicity of pyrrolizidine alkaloid-N-oxides could be greater than suggested hitherto as a result of conversion to the toxic metabolite via the parent alkaloid. Quantitative differences in the proportions of products formed by the different microsomal preparations may be of significance in the extrapolation of toxicological data from animal models such as the rat to humans.

Animals↗
PubMed1991

The manipulation of DNA with restriction enzymes in low water systems.

The cleavage of phage lambda (lambda) DNA by the restriction enzyme HindIII in low water systems has been investigated. Two types of low water systems have been studied--those which contain a surfactant in a reverse micelle environment and a surfactant-free system in which a solid support (celite) is used. The effect of the surfactants themselves in a normal aqueous environment has also been studied. Charged surfactants were found to greatly inhibit HindIII activity in aqueous buffer, while non-ionic surfactants did not affect either the activity or the specificity of the restriction enzyme. The rate of cleavage by HindIII in a reverse micelle system consisting of sodium dioctylsulphosuccinate is very slow, however, in a Triton B system the expected fragments are observed. In a surfactant-free low water environment, cleavage occurs at the expected sites but in a different order to that observed in normal aqueous systems. These results suggest that DNA tertiary structure in low water systems is different to that in aqueous solution and that this influences cleavage by the restriction enzyme HindIII.

Bacteriophage lambda↗
PubMed1989

The effect of feeding brassica vegetables and intact glucosinolates on mixed-function-oxidase activity in the livers and intestines of rats.

Significant induction of mixed-function-oxidase (MFO) activity was observed in the small intestines of rats within 4-6 hr of ingestion of a single meal containing a Brassica vegetable (cabbage). Intact Brussels sprouts and a fractionated methanol-water extract of Brussels sprouts induced similar degrees of MFO activity in the livers, and small and large intestines of rats. However, the residue left after extraction of the polar compounds did not induce MFO activity. Different amounts of the various naturally-occurring thioglycosides and glucosinolates were found in the intact Brussels sprouts and in the extract, but virtually none were found in the extracted residue. When glucusinolates that were found in Brussels sprouts (sinigrin, progoitrin, glucobrassicin and glucotropaeolin) were fed separately to rats, only the indole glucosinolate, glucobrassicin, induced MFO activity (causing induction in the small intestines of the rats). This is consistent with the inducing activity of the various hydrolysis products of this glucosinolate. This is the first study in which an attempt has been made to define the inducing compounds in Brassica vegetables by feeding the individual purified glucosinolates.

Animals↗
PubMed1988

Chemical and biological properties of indole glucosinolates (glucobrassicins): a review.

Glucosinolates are a group of secondary products commonly, but not exclusively, found in plants of the family Cruciferae. They give rise, upon enzymic hydrolysis, to a range of volatile, pungent and physiologically active compounds. Recently, particular attention has been focused upon those that are trytophan-derived--the indole glucosinolates (glucobrassicins). When chemically or enzymically hydrolysed these compounds give rise to a range of involatile indole compounds which have been implicated in the anti-carcinogenic and mixed-function-oxidase stimulatory activities of brassica vegetables. This review details the chemical and physiological properties of indole glucosinolates and their products and suggests possible areas for future research.

Animals↗
PubMed1987

Differential induction of mixed-function oxidase (MFO) activity in rat liver and intestine by diets containing processed cabbage: correlation with cabbage levels of glucosinolates and glucosinolate hydrolysis products.

Both white and Savoy-type cabbage added to a semi-purified diet at 25% dry weight and fed to rats ad lib. for 5 days significantly induced ethoxyresorufin (ERR) deethylation in the small and large intestine. Savoy cabbage also induced hepatic activity and, in general, exhibited a greater inducing effect than white cabbage. These enzyme-inducing effects were altered when the cabbage had been processed. The content of intact glucosinolate was greater in Savoy than in white cabbage. The indole glucosinolate (glucobrassicin) content of both types of cabbage was approximately halved by cooking but was unaffected by fermentation, whilst homogenization of Savoy cabbage led to the total disappearance of intact glucosinolates. Levels of the indole glucosinolate breakdown products ascorbigen and indole-3-carbinol were highest in homogenized cabbage, and ascorbigen levels were also higher in cooked than in fresh cabbage of either type. When added to the semi-purified diet and fed ad lib. to rats for 5 days, indole-3-carbinol was a potent inducer of hepatic ERR deethylation and cytochrome P-450 activity, but had much less effect in the intestine. Other glucobrassicin metabolites, diindolylmethane and indole-3-acetonitrile, also had some inducing effect in the liver but no effect in the intestine, while ascorbigen significantly induced ERR deethylation in the small and large intestine but had no effect on hepatic MFO activity.

Animals↗
PubMed1985

The genus Allium--Part 1.

Alliums have been grown for many centuries for their characteristic, pungent flavor and medicinal properties. The present review, which includes references published up to the middle of 1984, is primarily concerned with the chemical composition, flavor, and physiological properties of these crops, their extracts, and processed products. Special emphasis is placed upon the relationship between the organoleptically and biologically active components of onion and garlic. Following a brief historical introduction, current production of commercially important alliums is described and their botanical origins and interrelationships are explained. Following consideration of the major economic diseases and pests of alliums, the agronomic, husbandry, and practices associated with their cultivation are described, particular emphasis being placed upon the storage and processing of onion and garlic. The detailed, overall chemical composition and nutritional value of members of the genus Allium are presented in Section 7; after an outline of the origin and nature of flavor components and precursors, the flavor volatiles of individual members are presented. The effects of agronomic, environmental, and processing practices on chemical and flavor content and quality are considered in Section 9. The following section deals critically with the human and animal studies which have been conducted into the medical and therapeutic properties of alliums, emphasis being placed upon the studies into the antiatherosclerotic effect of onion and garlic and their essential oils. After a study of antimicrobial properties of alliums and their effects on insects and animals, an overview is presented which highlights unexplored or inadequately studied areas and suggests rewarding areas for future research.

Agriculture↗
PubMed1985

The genus Allium. Part 2.

Allium is a genus of some 500 species belonging to the family Liliaceae. However only a few of these are important as food plants, notably onion, garlic, chive, leek, and rakkyo. Such plants have been used for many centuries for the pungency and flavoring value, for their medicinal properties, and, in some parts of the world, their use also has religious connotations. The flavors of members of the genus Alliums, in addition to having certain characteristics, are also complex, being derived enzymically from a number of involatile precursors. In addition to there being variation of flavor between different alliums, there are also considerable changes that occur as a result of cooking and processing. Of course, these are of importance to the consumer and food technologist-processor. The review will introduce the subject by an historical perspective and will set this against data on the present cultivation and usage of commercially cultivated alliums. The chemical composition of these plants will be discussed, emphasis being given to nonvolatile constituents which are, perhaps, less often considered. Discussion of the volatile constituents, which will include mention of the methods currently used for their analysis and for the determination of "flavor strength", will be mainly concerned with literature taken from the last 5 years. In considering the extent and nature of allium cultivation and processing, factors affecting the nutritional value and quality will be highlighted. The medicinal properties of garlic and onion oils have been much studied over the last decade and the review will include critical assessment of this area and also will touch on the more general properties (antimicrobial, antifungal, antibacterial, and insecticidal) of these oils. Finally mention will be made of the antinutritional, toxic, or otherwise undesirable effects of alliums, for example, as inadvertent components of animal diets, tainting of milk and other food products. It is our intention to review the literature up to mid-1984.

Allium↗
PubMed1985

The genus Allium--Part 3.

Allium is a genus of some 500 species belonging to the family Liliaceae. However, only a few of these are important as food plants, notably onion, garlic, chive, leek, and rakkyo. Such plants have been used for many centuries for their pungency and flavoring value, for their medicinal properties, and in some parts of the world, their use also has religious connotations. The flavors of members of alliums, in addition to being characteristic, are also complex, being derived enzymically from a number of involatile precursors. As well as there being variation of flavor between different alliums there are also considerable changes that occur as a result of cooking and processing. These are, of course, of importance to the consumer and food technologist/processor. The review will introduce the subject by an historical perspective and will set against this data on the present cultivation and usage of commercially cultivated alliums. The chemical composition of these plants will be discussed, emphasis being given to nonvolatile constituents which are, perhaps, less often considered. Discussion of the volatile constituents, which will include mention of the methods currently used for their analysis and for the determination of "flavor strength," will be mainly concerned with literature taken from the last 5 years. In considering the extent and nature of allium cultivation and processing, factors affecting the nutritional value and quality will be highlighted. The medicinal properties of garlic and onion oils have been extensively studied over the last decade and the review will include critical assessment of this area; it will also touch on the more general properties (antimicrobial, antifungal, antibacterial, and insecticidal) of these oils. Finally, mention will be made of the antinutritional, toxic, or otherwise undesirable effects of alliums, for example, as inadvertant components of animal diets, tainting of milk, and other food products. It is our intention to review the literature up to mid-1984.

Allium↗
PubMed1985

Inhibition of carcinogenesis by some minor dietary constituents.

Previous work has shown that food contains a large number of minor dietary constituents that can inhibit the occurrence of cancer. Additional inhibitors from four different natural sources will be the subject of this presentation. 1. Citrus fruit oils. Orange, tangerine, lemon, and grapefruit oils given p.o. induce increased glutathione (GSH) S-transferase activity in tissues of the mouse. When fed in the diet prior to and during the course of administration of benzo(a)pyrene (BP), the four citrus fruit oils inhibit formation of tumors of both the forestomach and lungs of mice. When fed either before or after the administration of 7,12-dimethylbenz(a)anthracene (DMBA) orange oil inhibits mammary tumor formation. 2. Garlic oil. Allyl methyl trisulfide (AMT), a constituent of garlic oil, has been synthesized recently. When given p.o. 96 and 48 hr prior to BP, AMT inhibits the occurrence of forestomach tumors in mice. 3. Green coffee beans. Two diterpene esters, kahweol palmitate and cafestol palmitate, which are potent inducers of GSH S-transferase activity have been isolated from coffee beans. When administered p.o. prior to DMBA the two diterpene esters inhibit mammary tumor formation. 4. Cruciferous vegetables. Several glucosinolates occur in cruciferous vegetables. Efficient procedures for the isolation of these compounds have been developed recently. The inhibitory effects of three of these i.e. glucobrassicin, glucotropaeolin, and glucosinalbin were studied in several animal models. Glucobrassicin caused substantial inhibition of BP-induced neoplasia of the lung and forestomach of the mouse and DMBA-induced neoplasia of the breast in rats. Glucosinalbin and glucotropaeolin are less active in these systems. In addition to protective effects, indoles derived from the hydrolysis of glucobrassicin have potential harmful properties. The implications of multiple properties and factors which may determine their consequence will be discussed.

Animals↗