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Biomedical subjects

J A Robertson

Publications and source records attributed to J A Robertson.

At least 37 records · Page 2Linked to original sources
PubMed1999

Effects of heat treatment and dehydration on properties of cauliflower fiber.

The effects of heat treatment and dehydration on fiber structure and hydration properties, using cauliflower floret/curd and stem tissues, have been investigated. No major changes in fiber composition resulted from sample treatments, but the degree of esterification of pectic polysaccharides, approximately 60% in fresh cauliflower, decreased by approximately 12% in samples heated at temperatures >40 degrees C. Enzymic activity was considered to be responsible, through pectin methyl esterase activity. De-esterification was temperature and moisture sensitive. Hydration properties were also affected by processing conditions. The solubility of nonstarch polysaccharides in fresh, freeze-dried, and 40 degrees C dried samples was approximately 6% but increased to 12% in boiled samples and decreased in samples dried at 75 degrees C. Similar behavior occurred for swelling and water retention capacity (WRC), with swelling and WRC highest for boiled samples and lowest for samples dried at 75 degrees C. Hence, a decrease in de-esterification was not directly responsible for changes in hydration properties. The results demonstrate the importance of processing history on functional properties and on the preparation of fiber-rich ingredients for successful incorporation into foods.

Brassica↗
PubMed1999

Privacy issues in second stage genomics.

Research that identifies genes useful in the prevention and treatment of disease will require access to biologic samples and medical records protected by traditional notions of privacy and confidentiality. Resolving conflicts between privacy and genomic research will require articulating the ethical rules that should govern such practices and then implementing those rules in the national, regional, or local health systems in which the data of interest exists. As consensus develops about the ethical rules that should govern such research, attention will shift to the practical and political problems of installing and implementing those rules in the agencies and institutions where such research will occur.

Advisory Committees↗
PubMed1999

Ileal effluent as a fermentation substrate: implications for butyrate production in the colon.

Fermentation of fiber can lead to an enhanced production of short chain fatty acids (SCFA) and, hence, contribute to the proposed anticarcinogenic properties of butyrate in the colon. The fermentation of fiber isolates and the corresponding ileal effluents has been compared under in vitro conditions. Yield of SCFA per gram of substrate fermented was similar for isolates and fiber-enriched effluents (approximately 4.9 mmol/g) and it could be inferred that nonfiber components of effluent also generated SCFA. Butyrate production was highest for glucan-based polymers (approximately 30% total SCFA) and, from the measured acidogenic profile, production of SCFA will occur mainly in the proximal colon. The buffering capacity of ileal effluents during fermentation restrict the potential for a reduction in pH during acidogenesis compared to fiber isolates. This buffering capacity could limit the bioavailability of butyrate in the colon and, hence, the ability to satisfy the proposed antineoplastic properties of butyrate in the colon.

Anticarcinogenic Agents↗
PubMed1998

Tissue-related changes in methyl-esterification of pectic polysaccharides in cauliflower (Brassica oleracea L. var. botrytis) stems.

Pectic substances are a major component of cell walls in vegetable plants and have an important influence on plant food texture. Cauliflower (Brassica oleracea L. var. botrytis) stem sections at different regions of the mature plant stem have been monitored for tissue-related changes in the native pectic polysaccharides. Chemical analysis detected appreciable differences in the degree of methyl-esterification (ME) of pectic polysaccharides. About 65% of galacturonic acid (GalpA) residues were methyl-esterified in floret tissues. Relative ME showed a basipetal decrease, from 94% in the upper stem to 51% in the lower-stem vascular tissues. The decrease was not related to a basipetal increase in glucuronic acid (GlcpA) residues. The monoclonal antibodies, JIM 5 and JIM 7, produced distinct labelling patterns for the relatively low-methylesterified and high-methyl-esterified pectin epitopes, respectively. Labelling was related to cell type and tissue location in the stem. Floret cell walls contained epitopes for both JIM 5 and JIM 7 throughout the wall. Stem vascular tissues labelled more strongly with JIM 5. Whereas pith parenchyma in the upper stem labelled more strongly with JIM 7, in the lower-stem pith parenchyma, JIM 5 labelling predominated. Localization of pectic polysaccharide epitopes in cell walls provides an insight into how structural modifications might relate to the textural and nutritional properties of cell walls.

Brassica↗
PubMed1998

Tamoxifen up-regulates oestrogen receptor-alpha, c-fos and glyceraldehyde 3-phosphate-dehydrogenase mRNAs in ovine endometrium.

Tamoxifen, the antiestrogen most widely used in medicine, was tested in ewes to determine whether it antagonizes oestradiol up-regulation of ER, PR, and other genes reported to be oestrogen-modulated (c-fos, oxytocin receptor (OTR), glyceraldehyde phosphate dehydrogenase (GAPDH), and apolipoprotein AI (apo AI)) in endometrium and liver. Ovariectomized ewes (n = 6 ewes per group) were injected with 20 mg tamoxifen (Tam) 24 h prior to tissue collection, 50 microg oestradiol (E2) 18 h prior to tissue collection, both drugs (T + E2) or drug vehicle (Con). E2 treatment resulted in 857 +/- 93 pg oestradiol/g endometrium. Gross uterine characteristics of Tam- and T + E2-treated ewes were intermediate to those in Con and E2 groups. In endometrium, Tam treatment mimicked E2 treatment in up-regulating ER, c-fos, and GAPDH mRNAs two- or three-fold. However, neither E2 nor Tam treatments affected concentrations of OTR mRNA in endometrium, or ER, c-fos, GAPDH, OTR and apo AI mRNAs in liver. Like oestradiol, tamoxifen stabilized endometrial ER mRNA more than 3-fold in endometrial explants cultured with the transcription inhibitor 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB). Thus, tamoxifen acts as an oestradiol agonist in ovine endometrium and shares a posttranscriptional mechanism with oestradiol in the up-regulation of ER gene expression.

Animals↗
PubMed1998

Oocyte cytoplasm transfers and the ethics of germ-line intervention.

Author advances the discussion about positive genetic selection by looking at the use of oocyte cytoplasm transfers as a possible means to prevent disease and to overcome fertility, focusing on the issues of family and kinship, commodification of eggs and egg donors, and germ-line alterations.

Adult↗
PubMed1998

Development of a monoclonal antibody to a Ureaplasma urealyticum serotype 9 antigen.

We produced a monoclonal antibody (MAb) to Ureaplasma urealyticum Vancouver, the serotype 9 standard strain. By immunoblotting, this MAb showed a single, 85-kDa band with the homologous serotype and a minor, 100-kDa band with serotype 2 but did not react with any other serotype standard strain. Clinical isolates of U. urealyticum were tested with this MAb and with two sets of polyclonal antisera against the 14 serotype standard strains. The use of MAb 9-2H9 correctly identified certain serotype 9 strains but did not react with wild-type strains lacking the serotype 9 determinant.

Animals↗
PubMed1997

Release of mixed linkage (1-->3),(1-->4) beta-D-glucans from barley by protease activity and effects on ileal effluent.

The behaviour of barley beta-glucans in the upper gut has been assessed using ileal effluents recovered from a barley-based test meal. Results have been compared to in vitro treatments used to extract beta-glucans. In vitro, exposure to endogenous proteases led to a solubilisation of beta-glucan, ranging from 28% in the untreated to 83% following NSP isolation. In ileal effluent 60% of the beta-glucan was solubilised, similar to the in vitro treatment. However, the viscosity of the ileal effluent was low, comparable to a mucin standard. Although beta-glucan can be solubilised in the upper gut its viscosity would appear to have only a limited potential to affect nutrient bioavailability.

Carbohydrate Conformation↗
PubMed1997

Mycoplasma felis septic arthritis in a patient with hypogammaglobulinemia.

We describe the first documented case of Mycoplasma felis infection in a woman who had common variable immunodeficiency and who presented with septic arthritis of the left hip and right knee. M. felis was isolated from both joints. She had been exposed to cats before the diagnosis of M. felis septic arthritis was made. Both of the patient's joints were surgically debrided, and she was treated with doxycycline for several months. In spite of initial improvement, destruction of her hip was noted. Subsequently, she underwent hip arthroplasty; histopathological examination of the bone at the time of surgery showed chronic osteomyelitis, and doxycycline therapy was continued.

Agammaglobulinemia↗
PubMed1996

The effects of pH and bile salts on the binding of MeIQx to wheat bran fibre.

The effects of pH and of the bile salts, sodium cholate, chenodeoxycholate, taurocholate, deoxycholate and glycodeoxycholate on the adsorption of the heterocyclic aromatic amine mutagen and carcinogen 2-amino-3,8-dimethylimidazo[4,5-f]-quinoxaline (MeIQx) onto wheat bran cell wall material have been examined. The highest binding affinity of MeIQx for bran was at pH 5.5. Binding affinity declined more rapidly with pH > 5.5 than with pH < 5.5. Bile salts in solution did not appreciably affect the binding of MeIQx to bran, but where the bile salts formed a suspension then the adsorption was reduced. Where precipitation of bile salts occurred then the free concentration of MeIQx was also reduced, indicating that MeIQx binding/immobilization could be enhanced through interaction with bile salts.

Bile Acids and Salts↗