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Biomedical subjects

C A Edwards

Publications and source records attributed to C A Edwards.

At least 37 records · Page 2Linked to original sources
PubMed2000

Antioxidant flavonols from fruits, vegetables and beverages: measurements and bioavailability.

Flavonols are polyphenolic secondary plant metabolites that are present in varying levels in commonly consumed fruits, vegetables and beverages. Flavonols have long held an interest for nutritionists, which has increased following a Dutch study in the early 1990's showing that dietary intake of flavonols was inversely correlated with the incidence of coronary heart disease. The main factors that have hindered workers in the field of flavonol research are (i) the accurate measurement of these compounds in foods and biological samples, and (ii) a dearth of information on their absorption and metabolism. This review aims to highlight the work of the authors in attempting to clarify the situation. The sensitive and selective HPLC procedure to identify and quantify common flavonols and their sugar conjugates is described. In addition, the results of an on-going screening program into the flavonol content of common produce and beverages are presented. The bioavailability of dietary flavonols is discussed with reference to an intervention study with onions, as well as pilot studies with tea, red wine and cherry tomatoes. It is concluded that flavonols are absorbable and accumulate in plasma and that consuming high flavonol-containing varieties of fruits and vegetables and particular types of beverages could increase their circulatory levels.

Antioxidants↗
PubMed1999

Cellular localization of a Hsp90 homologue in Porphyromonas gingivalis.

We previously reported an association between elevated serum antibody titers to the 90-kDa human heat shock protein (Hsp90), periodontal health and colonization by Porphyromonas gingivalis. In this study, we examined the cellular localization of the Hsp90 homologue of P. gingivalis. Cultures of P. gingivalis were heat-stressed (45 degrees C) and examined for localization of the Hsp90 homologue. Heat stress induced a 4-5-fold increase in anti-Hsp90 antibody reactivity over that of the unstressed controls. Western blot analysis revealed two bands (44 and 68 kDa) that reacted with anti-Hsp90 antibodies. The 68-kDa band was heat-inducible, while the 44-kDa band was not. Immunogold staining revealed that the Hsp90 homologue localized principally to the membrane and extracellular vesicles. Subcellular fractionation confirmed that the Hsp90 homologue was primarily membrane-associated.

Blotting, Western↗
PubMed1999

Hepatic apoptotic activity following transient normothermic inflow occlusion and reperfusion in the swine model.

Accelerated hepatic apoptosis was first described in portal vein-ligated livers but has since been reported in a variety of liver injuries. Because porto-prival states can induce apoptosis we sought to determine whether transient ischemic periods followed by reperfusion would trigger such cell death. The cytokines TNF-alpha and TGF-beta are known to facilitate apoptosis and are released in response to a number of stimuli including ischemia. We also investigated alterations in plasma and tissue levels of these cytokines which might lend support to their role in increased apoptotic activity following ischemia/reperfusion. Female pigs were used as the experimental model. Inflow occlusion of portal and hepatic arterial blood was performed to a portion of the swine liver directing the entire splanchnic flow to the remaining hepatic lobes for a period of 2 h. The livers were then reperfused and plasma and tissue samples taken for determination of apoptotic activity utilizing cell death immunoperoxidase staining of 3'-OH DNA ends generated by fragmentation and ELISA assay of histone-associated DNA fragments. Plasma and tissue levels of TNF-alpha and plasma levels of TGF-beta were determined by ELISA assay. An increase in apoptotic activity following reperfusion was seen at Day 2 and Day 4 compared to preischemic values by the cell death stain. The ELISA cell death assay showed an increase in apoptotic activity at 60 min, Day 2, and Day 4. Moreover, the ELISA cell death assay showed enhanced apoptotic activity in "hyperperfused" hepatic lobes compared to preischemic, or resting, liver. This was also observed when compared to sham-operated animals. Surprisingly, there was no detectable increase in plasma TNF-alpha or TGF-beta levels following ischemia/reperfusion, although homogenized liver TNF-alpha levels were increased at 60 min and Day 2 following reperfusion. We conclude that transient hepatic inflow occlusion followed by reperfusion can induce increased apoptotic activity in the swine model. Furthermore, increased apoptotic activity also occurs in the hyperperfused liver raising the possibility of a locally active factor or global hepatic expression of receptor activity in response to ischemia/reperfusion. This period of ischemia/reperfusion did not produce a detectable increase in circulating cytokine levels, and accelerated apoptosis could not be linked to heightened TNF-alpha or TGF-beta plasma activity. Higher tissue levels of TNF-alpha could reflect enhanced binding to TNF cell surface receptors or amplified receptor expression.

Animals↗
PubMed1999

Cytotoxic effects of current dental adhesive systems on immortalized odontoblast cell line MDPC-23.

OBJECTIVES: Evaluate the cytotoxic effect of the three dental adhesive systems. METHODS: The immortalized mouse odontoblast cell line (MDPC-23) was plated (30,000 cell/cm2) in 24 well dishes, allowed to grow for 72 h, and counted under inverted light microscopy. Uncured fresh adhesives were added to culture medium to simulate effects of unset adhesive. Three adhesives systems were applied for 120 min to cells in six wells for each group: Group 1) Single Bond (3M), Group 2) Prime & Bond 2.1 (Dentsply), and Group 3) Syntac Sprint (Vivadent). In the control group, PBS was added to fresh medium. The cell number was counted again and the cell morphology was assessed under SEM. In addition, the adhesive systems were applied to circles of filter paper, light-cured for 20 s, and placed in the bottom of 24 wells (six wells for each experimental materials and control group). MDPC-23 cells were plated (30,000 cell/cm2) in the wells and allowed to incubate for 72 h. The zone of inhibition around the filter papers was measured under inverted light microscopy; cell morphology was evaluated under SEM; and the MTT assay was performed for mitochondrial respiration. RESULTS: The fresh adhesives exhibited more toxic (cytopathic effects) to MDPC-23 cells than polymerized adhesives on filter papers, and as compared to the control group. The cytopathic effect of the adhesive systems occurred in the inhibition zone around the filter papers, which was confirmed by the MTT assay and statistical analysis (ANOVA) combined with Fisher's PLSD test. In the control group, MDPC-23 cells were dense on the plastic substrate and were in contact with the filter paper. In the experimental groups, when acid in the adhesive systems was removed by changing the culture medium, or when the adhesives were light-cured, some cells grew in the wells in spite of the persistent cytotoxic effect. SIGNIFICANCE: All dentin adhesive systems were cytotoxic odontoblast-like cells. Both acidity and non-acidic components of these systems were responsible for the high cytopathic effect of those dental materials.

Analysis of Variance↗
PubMed1999

Energy balance during acute respiratory exacerbations in children with cystic fibrosis.

Acute respiratory exacerbations have been proposed to contribute to the negative energy balance which causes undernutrition in cystic fibrosis. However, no studies have measured their effect on all components of energy balance. The aim of this study was to measure the effect of an acute respiratory exacerbation on energy balance. Fourteen children (six females, eight males, mean+/-SD age 9.9+/-2.4 yrs) were studied when well and during the course of an acute respiratory exacerbation treated with intravenous antimicrobial therapy. The total energy expenditure was measured using the doubly-labelled water method, resting energy expenditure by ventilated hood indirect calorimetry, energy intake by household measures records, and fat malabsorption from measurements of dietary fat intake and faecal fat output. The exacerbation was associated with a significant reduction in energy intake (mean paired difference 47 kJ x kg of body weight(-1) x day(-1), p<0.01). Changes in fat malabsorption and resting energy expenditure were negligible. The absence of significant changes in body weight and composition, together with the trend towards lower total energy expenditure, suggested no marked negative energy balance during the exacerbation. In conclusion, treatment of acute respiratory exacerbation with intravenous antimicrobial therapy represents a relatively minor challenge to energy balance and nutritional status in children with cystic fibrosis.

Acute Disease↗
PubMed1999

Adequacy of standards for assessment of growth and nutritional status in infancy and early childhood.

BACKGROUND: New "UK 1990" data have been proposed for assessing growth and nutritional status in infancy and childhood. These are still largely untried in clinical practice. There is also doubt about the applicability of more traditional reference data, which are still widely used, in assessing length, weight, skinfold thicknesses, and head circumference. AIMS: To determine the suitability of new and traditional reference data for the assessment of growth and nutritional status in infancy and early childhood. METHODS: 127 infants were recruited at birth and assessed monthly to 6 months of age then at 9, 12, 18, and 24 months. Length, weight, head circumference, and triceps and subscapular skinfold thicknesses were measured. Body mass index (BMI) was calculated. Measurements were expressed as standard deviation scores relative to "revised UK 1990" data for weight, length, head circumference and BMI; relative to Tanner-Whitehouse data for skinfold thicknesses; and relative to Gairdner-Pearson standards for head circumference. Agreement at the extremes of the distribution was assessed by comparison of observed and expected frequencies above the 90th and below the 10th centile. RESULTS: Compared with the revised UK 1990 references small differences were found for weight, length, head circumference, and BMI. Mean head circumference exceeded Gairdner-Pearson standards at all ages. Triceps and subscapular skinfold thicknesses were substantially below Tanner-Whitehouse reference data at all ages and in both sexes. CONCLUSION: Biases in revised UK 1990 reference data are small and not clinically important. The new standards are considerably more appropriate than older reference data. Use of older reference data for head circumference and skinfold thicknesses is inappropriate.

Body Height↗
PubMed1998

Probing site-specific interactions in protein-DNA complexes using heteronuclear NMR spectroscopy and molecular modeling: binding of Cro repressor to OR3.

In this paper, a general method is developed to study site-specific interactions in DNA-protein complexes using heteronuclear NMR spectroscopy and molecular modeling. This method involves two steps: (a) homonuclear 1H NMR and molecular modeling are used to develop a low resolution model and (b) 15N7-guanosine containing oligonucleotides are employed to probe the specific intermolecular interactions predicted in (a). This method is applied to Cro-operator complex due to its small size and extensive prior characterization. Non-exchangeable and exchangeable base protons have been assigned by nuclear Overhauser effect spectroscopy (NOESY) and chemical shift correlation spectroscopy. Extensive line-broadening has been observed in the 1H NMR spectra of the operator DNA in the presence of protein. Differential line-broadening observed in the imino proton region and the comparison of NOESY spectra in the presence and absence of Cro protein show that guanosine-12 and guanosine-14 are involved in the Cro-DNA interaction, while the three A.T base-pairs at the 3'- and 5'-termini play only a minor role in the binding. A model of the Cro-operator DNA complex has been constructed by docking helix-3 of the Cro protein in the major groove and it predicted specific hydrogen bonds between N7 of guanosines-12 and -14 and the side-chain of Lys-32 and Ser-28, respectively. The appearance of a new resonance in the temperature dependent proton detected heteronuclear multiple quantum coherence (HMQC) spectra of the Cro-DNA complex also demonstrates a specific interaction of Cro with guanosine-14 of the operator DNA.

DNA↗
PubMed1998

Absorption and excretion of conjugated flavonols, including quercetin-4'-O-beta-glucoside and isorhamnetin-4'-O-beta-glucoside by human volunteers after the consumption of onions.

Flavonols are polyphenols found ubiquitously in plants and plant-products. Flavonols, particularly quercetin, are potent antioxidants in vitro and their intake has been associated inversely with the incidence of coronary heart disease. The aim of this study was to investigate the accumulation in plasma and excretion in urine of flavonol glucosides following ingestion of lightly fried onions. Five healthy volunteers followed a low-flavonoid diet for 3 days. On day 4, after an overnight fast, subjects were given 300 g of lightly fried yellow onions which contain conjugates of quercetin and isorhamnetin, including quercetin-3,4 '-diO-beta-glucoside, isorhamnetin-4'-O-beta-glucoside and quercetin-4'-O-beta-glucoside. Blood collection was carried out at 0 min, 0.5, 1.0, 1.5, 2, 3, 4, 5 and 24h after the supplement. In addition, subjects collected all their urine for 24h following the onion supplement. Isorhamnetin-4'-O-beta-glucoside and quercetin-4 '-O-beta-glucoside accumulated in plasma with maximum levels, defined as proportion of intake, of 10.7+/-2.6% and 0.13+/-0.03% respectively. The time of the quercetin-4'glucoside peak plasma concentration was 1.3+/-0.2 h after the ingestion of onions while a value of 1.8+/-0.7 h was obtained for isorhamnetin-4'-glucoside. Excretion in urine, as a proportion of intake, was 17.4+/-8.3% for isorhamnetin-4'-O-beta-glucoside and 0.2+/-0.1% for quercetin-4'-O-beta-glucoside. Possible reasons for the accumulation and excretion of isorhamnetin-4'-glucoside in proportionally much higher amounts than quercetin-4'-glucoside are discussed. It is concluded that flavonols are absorbed into the bloodstream as glucosides and minor structural differences affect markedly both the level of accumulation and the extent to which the conjugates are excreted.

Adult↗
PubMed1998

Dentin-specific proteins in MDPC-23 cell line.

Only four established odontoblast-like cell lines have been reported in the literature (1-6). Of the four, only two synthesize dentin-specific proteins. These studies report that the cell line MO6-G3 synthesizes phosphophoryn (DPP), dentin sialoprotein (DSP) and dentin matrix protein-1 (DMP-1) while MDPC-23 synthesizes DSP, but not DMP-1. The objective of the present study was to determine whether polyclonal antibodies to rat DSP and DPP would label odontoblasts on microscopic sections of day-19 fetal mouse incisor odontoblasts as well as cultured cells of the MDPC-23 cell line. The spontaneously immortalized MDPC-23 cell line was derived from fetal mouse molar papillae, made continuous by the 3T6 method and cloned by dilution. These cultures have been passaged 77 times after cloning, form multilayered nodules, and have high alkaline phosphatase activity. The data show positive reactivity in odontoblasts in 19-d mouse fetal incisors as well as in cultures of MDPC-23 cells by fluorescence and confocal microscopy. In addition, these cultures were characterized by phase microscopy and scanning and transmission electron microscopy. These findings suggest that MDPC-23 cells are of the odontoblast lineage.

Animals↗
PubMed1998

Weaning practice in the Glasgow Longitudinal Infant Growth Study.

AIMS: To assess compliance with Department of Health guidelines on weaning practice in a representative sample of 127 infants from Glasgow, and to identify factors influencing timing of weaning. METHODS: Questionnaires on feeding and weaning were completed during home visits. Ninety eight mothers completed a further questionnaire on attitudes to weaning. RESULTS: Median age at introduction of solid food was 11 weeks (range 4-35 weeks); only 7% of infants had not been weaned before age 4 months. There was no difference in timing of weaning between boys and girls. Younger mothers (< 20 years old), those of lower socioeconomic status, and those who formula fed their infants tended to introduce solids earlier. Infants who were heaviest before weaning were weaned earlier. Seventy three of 98 mothers reported that they weaned their babies because they felt that they required more food. Sources of information influencing time of weaning were previous experience (53/98), books and leaflets (43/98), advice from the health visitor (31/98), and family and friends (15/98). Sixty five of 98 mothers reported receiving formal information on weaning, in most cases (54) this was from the health visitor. Mothers who received formal information tended to wean their infants later. Two per cent of infants had been given cow's milk as a main drink by age 6 months, 17% by 9 months, and 45% by the end of the first year. CONCLUSION: Compliance with recommendations on timing of weaning (not before 4 months), weaning foods, and cow's milk consumption in Glasgow is poor, although no poorer than in many other areas of the UK as found by Office of Population, Censuses and Surveys. Public health messages in relation to weaning may not be reaching their target audience.

Age Factors↗
PubMed1998

Cloned 3T6 cell line from CD-1 mouse fetal molar dental papillae.

Only primary pulpal cell cultures and one virally transformed mouse cell culture have been formally reported in the literature to synthesize proteins such as phosphophoryn which are unique to dentin matrix. In the present study, a mixed culture was derived from dental papilla cells of 18-19 fetal day CD-1 mouse mandibular first molars, maintained on a 3T6 plating regimen, and subsequently cloned after 28 passages. This cloned cell line (MDPC-23) exhibited several unique features, some of which were characteristic of odontoblasts in vivo. The features of this cell line included (1) epithelioid morphology of all cells with multiple cell membrane processes, (2) high alkaline phosphatase activity in all cells, (3) formation of multilayered nodules and multilayered cultures when maintained in ascorbic acid and beta-glycerophosphate, and (4) expression of two markers for odontoblast differentiation, i.e. dentin phosphoprotein and dentin sialoprotein.

Animals↗
PubMed1997

Immunoglobulin binding protein (BiP) function is required to protect cells from endoplasmic reticulum stress but is not required for the secretion of selective proteins.

BiP/GRP78 is a lumenal stress protein of the endoplasmic reticulum (ER) that interacts with polypeptide folding intermediates transiting the secretory compartment. We have studied the secretion and the stress response in Chinese hamster ovary (CHO) cells that overexpress either wild-type immunoglobulin binding protein (BiP) or a BiP deletion molecule (residues 175-201) that can bind peptides and ATP but is defective in ATP hydrolysis and concomitant peptide release. Overexpressed wild-type BiP was localized to the ER and unique vesicles within the nucleus, whereas overexpressed ATPase-defective BiP was localized to the ER and cytoplasmic vesicles but was absent from the nucleus. Compared with wild-type CHO cells, overexpression of ATPase-defective BiP prevented secretion of factor VIII, a coagulation factor that extensively binds BiP in the lumen of the ER. Under these conditions factor VIII was stably associated with the ATPase-defective BiP. In contrast, the secretion of monocyte/macrophage colony stimulating factor, a protein that is not detected in association with BiP, was not affected by overexpression of ATPase-defective BiP. These results show that BiP function is not required for secretion of some proteins and suggest that some proteins do not interact with BiP upon transport through the ER. The presence of unfolded protein in the ER induces transcription of BiP and also elicits a general inhibition of protein synthesis. Overexpression of wild-type BiP prevented the stress-mediated transcriptional induction of BiP in response to either calcium ionophore A23187 treatment or tunicamycin treatment. In contrast, overexpression of ATPase-defective BiP did not prevent the stress induction of BiP, showing that the ATPase activity is required to inhibit transcriptional induction. Overexpression of wild-type BiP, but not ATPase-defective BiP, increased survival of cells treated with A23187. The increased survival mediated by overexpressed wild-type BiP correlated with reduced translation inhibition in response to the stress condition. These results indicate that overexpressed BiP alleviated the stress in the ER to prevent BiP transcriptional induction and permit continued translation of cellular mRNAs.

Adenosine Triphosphatases↗
PubMed1997

Colonic fermentation capacity in vitro: development during weaning in breast-fed infants is slower for complex carbohydrates than for sugars.

Fresh feces from 27 healthy infants-12 breastfed (complete, exclusive breast-feeding), 7 in early weaning (partial, high breast-feeding), and 8 in late weaning (partial, low breast-feeding)-were cultured with simple and complex carbohydrates in vitro to test the hypothesis that colonic fermentation capacity for carbohydrates increases during weaning. Infants in all three groups were able to ferment sugars, with no significant differences in median total short-chain fatty acid (SCFA) concentrations (mmol/L): preweaning, 56.4(range: 0-77.6); early weaning 68.5(range: 57.9-98.8); late weaning, 61.3(range: 28.6-120.4) for glucose. Preweaned infants were less able to ferment oligosaccharides and complex carbohydrates than were weaned infants (P < 0.05). Ability to ferment raftilose was higher in early weaning; median total SCFA concentrations (mmol/L) were as follows: preweaning 31.0 (range: 3.6-48.9), early weaning 57.1 (range: 2.5-70.6), late weaning 68.6 (range: 22.0-113.4) (P < 0.05). Ability to ferment complex carbohydrates did not develop until late weaning; median total SCFA concentrations for guar gum (mmol/L) were as follows: preweaning 6.4 (range: 0.1-57.3), early weaning 18.4 (range: 0.0-40.5), late weaning 45.4 (range: 15.6-62.1) (P < 0.05, preweaning and early weaning compared with late weaning). Development of the ability to ferment complex carbohydrate was slow. Cultures of feces from preweaned infants produced eight times more SCFAs with glucose than with complex carbohydrates, at early weaning there was a threefold difference and by late weaning the difference was only 25%, but this was still only 42% of the SCFAs produced by cultures of adult feces. These data suggest that for the complex carbohydrates tested, colonic fermentation is likely to contribute only a small proportion of daily energy needs of weaning infants.

Breast Feeding↗