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Biomedical subjects

K J Scott

Publications and source records attributed to K J Scott.

At least 19 recordsLinked to original sources
PubMed1997

Absorption of all-trans and 9-cis beta-carotene in human ileostomy volunteers.

1. Mass balance studies were carried out in fasted ileostomy subjects (n = 5) given an oral physiological dose (10 mg) of beta-carotene [all-trans: 9-cis, 84:16 (w/w)] dispersed in vegetable oil. Blood and ileal effluent samples were collected and analysed for beta-carotene. 2. Results showed that 90% (range 97.0-74.3%) of the total beta-carotene was absorbed without measurable perturbation of plasma total beta-carotene concentration, or change in the all-trans: 9-cis beta-carotene ratio. Peak loss of beta-carotene in ileal effluent occurred at 4.9 h (range 2.9-8.4 h) postingestion, and no further loss was detected after 5.4-12.4 h, depending upon the individual. Comparison of the ratio of all trans-beta-carotene to 9 cis-beta-carotene in the test meal and effluent indicated that isomerization did not occur during passage through the gastrointestinal tract and that both isomers were similarly absorbed. However, the all-trans: 9-cis beta-carotene ratio of the plasma did not change. Reasoned assumptions allowed the construction of a mathematical model of plasma beta-carotene disposal. 3. It is concluded that physiological doses of isolated all-trans and 9-cis beta-carotene are well absorbed without necessarily causing detectable excursions in plasma beta-carotene concentrations, or altering the ratio of all-trans to 9-cis beta-carotene. Isomerization of beta-carotene does not occur during passage through the gastrointestinal tract. Absorbed beta-carotene is rapidly cleared from the plasma to an unobservable pool at a rate similar to that of chylomicron triacylglycerol.

Colitis, Ulcerative↗
PubMed1996

The correlation between the intake of lutein, lycopene and beta-carotene from vegetables and fruits, and blood plasma concentrations in a group of women aged 50-65 years in the UK.

The correlations between the mean of 4 d weighed intakes of lutein, lycopene and beta-carotene and mean plasma concentrations during each of the four seasons were lutein r 0.64, lycopene r 0.47 and beta-carotene r 0.45. Intake was not significantly correlated with plasma concentrations during every seasonal time-point. There was a significantly higher intake of lutein during the spring compared with summer and autumn, lycopene intake was significantly higher during the summer and autumn and there were no significant seasonal differences in beta-carotene intake. There were, however, significant seasonal differences in plasma carotenoid concentrations, the highest levels occurring between May and October. There were large inter- and intra-individual variations in intake and plasma concentrations of carotenoids. BMI was inversely correlated with plasma beta-carotene (r-0.41). The findings suggest that plasma carotenoid concentrations are indicative of dietary intake, but the large intra-individual variation in plasma concentrations indicates that any assessment of longer-term status from data at any one time-point should be treated with caution.

Aged↗
PubMed1994

Gene family encoding basic pathogenesis-related 1 proteins in barley.

A genomic (prb1) and two cDNA clones (PRb1-2 and PRb1-3) corresponding to two new barley basic PR-1 proteins (prb1-2 and prb1-3) were isolated from Hordeum vulgare. Genomic analysis of DNA suggests that the barley genome contains at least 6 members corresponding to the gene family encoding PR-1 proteins. Expression of these genes was induced in primary leaf tissues of the H. vulgare cv. Psaknon 4* (F14) Man. carrying Mlp resistance gene (cv. Mlp) and the near-isogenic susceptible cultivar (cv. mlp) after inoculation with Erysiphe graminis f. sp. hordei.

Amino Acid Sequence↗
PubMed1994

Pregnancy enhances cocaine's actions on the heart and within the peripheral circulation.

OBJECTIVE: Our purpose was to determine whether cocaine's enhanced cardiovascular actions in pregnancy are cardiac alone or involve the peripheral vascular system. STUDY DESIGN: Six pregnant and five nonpregnant ewes chronically instrumented for heart rate, blood pressure, cardiac output, and systemic vascular resistance were given cocaine at 1.0 and 2.0 mg/kg and monitored for 60 minutes. Blood samples for cocaine levels were taken at 5, 15, 30, and 60 minutes. RESULTS: Cocaine initially (first 60 seconds) produced increased heart rate, decreased cardiac output, decreased stroke volume, and increased cardiac oxygen consumption, which were greater in pregnant than nonpregnant ewes. After 1 minute recovery of cardiac responses was accompanied by increased systemic vascular resistance, which was greater at each dose in pregnant than nonpregnant ewes. Cocaine levels at 5 minutes for pregnant ewes were eightfold to tenfold higher than for nonpregnant ewes. CONCLUSION: Cocaine produces cardiovascular alterations that are dose and time related but, in each case, enhanced in pregnant ewes. Cocaine metabolism may contribute to this pregnancy-related phenomenon.

Animals↗
PubMed1993

Structure and expression of a barley acidic beta-glucanase gene.

A barley acidic beta-1,3-glucanase gene was recovered from a barley genomic library by homology with a partial cDNA of barley basic beta-1,3-glucanase isoenzyme GII. The gene, Abg2, is homologous to the PR2 family of pathogenesis-related beta-1,3-glucanase genes. The ABG2 protein has 81% amino acid similarity to barley basic beta-1,3-glucanase GII. The ABG2 protein is encoded as a preprotein of 336 amino acids including a 28 amino acid signal peptide. A 299 bp intron occurs within codon 25. The mature ABG2 protein has a predicted mass of 32,642 Da and a calculated isoelectric point of 4.9. The second exon of the Abg2 gene shows a strong preference for G + C in the third position of degenerate codons. The Abg2 gene was functionally expressed in Escherichia coli. Abg2 mRNA is constitutively expressed in barley root; leaf expression of Abg2 mRNA is induced by mercuric chloride and infection by Erysiphe graminis f. sp. hordei. Southern blot analysis indicates that Abg2 is a member of a small gene family.

Acids↗
PubMed1993

A cDNA clone for a pathogenesis-related protein 1 from barley.

A barley cDNA clone (PRb-1) corresponding to an mRNA differentially induced in resistant compared to susceptible barley cultivars by powdery mildew infection was isolated and characterised. The deduced amino acid sequence revealed 24 amino acids comprising the signal peptide and 140 amino acids of the mature peptide (15 kDa). This showed close homology to PR-1-like proteins, which have been isolated from maize, tobacco, tomato and Arabidopsis thaliana. Northern blot analysis showed accumulation of the corresponding mRNA 12 h after inoculation of resistant barley cultivars with Erysiphe graminis. Increased expression of the PRb-1 gene was also observed in resistant compared with near-isogenic susceptible barley plants following treatment with ethylene, salicylic acid, methyl jasmonate and 2,6-dichloro-isonicotinic acid.

Amino Acid Sequence↗
PubMed1991

Induction of beta-1,3-glucanase in barley in response to infection by fungal pathogens.

The sequence of a partial cDNA clone corresponding to an mRNA induced in leaves of barley (Hordeum vulgare) by infection with fungal pathogens matched almost perfectly with that of a cDNA clone coding for beta-1,-3-glucanase isolated from the scutellum of barley. Western blot analysis of intercellular proteins from near-isogenic barley lines inoculated with the powdery mildew fungus (Erysiphe graminis f. sp. hordei) showed a strong induction of glucanase in all inoculated lines but was most pronounced in two resistant lines. These data were confirmed by beta-1,3-glucanase assays. The barley cDNA was used as a hybridization probe to detect mRNAs in barley, wheat (Triticum aestivum), rice (oryza sativus), and sorghum (Sorghum bicolor), which are induced by infection with the necrotrophic pathogen Bipolaris sorokiniana. These results demonstrate that activation of beta-1,3-glucanase genes may be a general response of cereals to infection by fungal pathogens.

Ascomycota↗
PubMed1987

Detection of polyols and sugars by cuprammonium ion in the presence of strong base.

A new and more sensitive cuprammonium reagent containing strong base has been developed for the colorimetric detection of polyols and sugars. A reagent blank with an absorbance at 280 nm, less than half that of previous methods, was achieved by reducing the cupric ion and ammonia concentrations to 1 mM (from 5 mM) and 0.4 M (from 2.25 M), respectively, and adding 0.2 M sodium hydroxide. Polyols are particularly well suited to the new method, showing up to an eightfold increase in sensitivity. The new reagent is readily applicable to the postcolumn detection of polyols and sugars after high-performance liquid chromatography and is linear over the range 40-180 nmol for D-glucitol (sorbitol) and 10-300 nmol for glucose, using standard HPLC equipment.

Carbohydrates↗
PubMed1987

Measurement of cytochrome f in thylakoids of higher plants using quantitative gel electrophoresis.

A quantitative method was developed to estimate the concentration of cytochrome (cyt) f in isolated thylakoids, using sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by staining with a heme-specific reagent containing 3,3',5,5'-tetramethylbenzidine and hydrogen peroxide. This densitometric technique was at least as sensitive as difference spectroscopy. Analysis of thylakoid preparations by densitometry of stained bands using cyt c as standard gave molar ratios of cyt/chlorophyll which were identical to ratios obtained by difference spectroscopy. Densitometric assays demonstrated that the molar ratio of cyt f/chlorophyll decreased during leaf aging in seven higher plants; however, there was a marked difference in the rate at which cyt f was lost from the leaves of different species.

Benzidines↗
PubMed1985

Nutrient content of milk and milk products: water soluble vitamins in baby milk formulae.

A study of the content of water soluble vitamins in the 12 baby milk formulae available in the UK in April 1983 showed that levels of vitamins in the individual brands were generally in excess of those declared by the manufacturer. For cows' milk based formulae the mean excess of vitamins over the declared level was 94%. Vitamin levels in prepared formulae averaged three times the minimum recommended level. The average level of B vitamins in prepared cows' milk based formulae was six times higher than in mature human milk. For the two soya based products, the levels of vitamins were generally in excess of the declared level and levels of vitamin B12, biotin and, in one sample, vitamin B6 were considerably in excess of those found in mature human milk.

Animals↗
PubMed1983

Trace-nutrient-binding proteins in milk and the growth of bacteria in the gut of infant rabbits.

1. The influence of trace-nutrient-binding proteins on the growth of coliforms, streptococci and lactobacilli in the gastrointestinal tract was examined in neonatal rabbits delivered germ-free and dosed with an artificial flora (ESL), or born conventionally and dosed with ESL or rabbit faeces. 2. In the stomach and small intestine of both gnotobiotic and conventional animals the counts of coliforms were usually atypically high and those of streptococci were always low. In the colon the counts of coliforms and streptococci were high. Lactobacilli usually became established in the gut of the gnotobiotic animals but were not found in the conventional rabbits. 3. Sterilization (freeze-drying followed by gamma-irradiation) of the milk decreased its capacity to bind added iron by 45% and vitamin B12 by 30%. When compared with raw milk, feeding of radiation-sterilized milk did not affect the viable count of coliforms and streptococci in the gut of gnotobiotic animals. 4. Saturating the nutrient-feeding proteins in milk with Fe, folic acid and vitamin B12 had no effect on the numbers of coliforms, streptococci and lactobacilli recovered from the intestine.

Animals↗
PubMed1982

Composition of milk from red and grey kangaroos with particular reference to vitamins.

Analysis of milk from red and grey kangaroos confirmed that the composition of milk from individual mammary glands changes with advancing age of the associated suckled young. Although the proportion of particular components may change, concentration of solids, in particular fats and to a lesser extent protein and casein, increase throughout lactation. The results of analyses to determine the vitamin content of kangaroo milks are presented for the first time.

Aging↗
PubMed1981

The preparation and properties of folate-binding protein from cow's milk.

An improved affinity-chromatographic method for the preparation of folate-binding protein from cow's milk is described. Under dissociating conditions the protein appeared homogeneous in the ultracentrifuge, with a molecular weight of 35 000 +/- 1500, but it was heterogeneous on electrophoresis and ion-exchange chromatography and evidently consisted of several glycoproteins with similar molecular weights that all bound folic acid. Overall, the protein contained a high proportion of half-cystine (18 residues/molecule) and 10.3% of carbohydrate. At saturation it bound approx. 1 mol of folate/mol of protein at pH 7.2. Equilibrium-dialysis measurements of the binding of folic acid and 5-methyltetrahydrofolate to the purified protein gave non-linear Scatchard plots, the shapes of which depended on pH. The results were interpreted in terms of ligand binding to a polymerizing system in which the affinity of ligand for monomer was greater than its affinity for polymer. When the protein concentration was similar to that in cow's milk, dissociation constants (Kd) for folate and 5-methyltetrahydrofolate were 3 nM and 5 nM respectively at pH 7.2 and 37 degrees C, whereas Kd for the binding of folate to monomer was about 50 pM. The properties of the binding protein are discussed in relation to its possible role in folate absorption in the gut.

Amino Acids↗
PubMed1981

Auditory-visual conflicts in the perceived duration of lights, tones and gaps.

The perceived duration of a short tone (1,000 or 1,500 msec) was longer than that of a separately presented light of equal length. Thus, when light and tone were presented simultaneously, there was a conflict in perceived duration. In that case, the perceived duration of an interval filled with both light and tone was close to that of an interval filled with tone alone. A silent gap in otherwise continuous tone was perceived as longer than a gap in otherwise continuous light, and the perceived duration of a gap occurring simultaneously in both light and tone was close to that of a gap in tone alone. Thus, auditory dominance occurred under the preceding conditions-that is, auditory-visual conflicts in perceived duration, whether occurring between filled intervals or gaps, were resolved in favor of the auditory modality. Visual dominance occurred only under one condition, in which the intensity of tone was reduced, and in which the perceived duration of a 500-msec light was longer than that of a 500-msec tone. The finding of auditory dominance in the perception of time runs counter to the results of studies of sensory conflicts in spatial perception, where vision typically dominates audition and touch.

Adolescent↗
PubMed1977

The B-vitamin content of baboon (Papio cynocephalus) milk.

1. The B-vitamins in milk from baboons (Papio cynocephalus) at various stages of lactation were measured microbiologically. 2. Mature milk contained, on average (microgram/ml): thiamin 0.18 riboflavin 0.74, nicotinic acid 3.2, folate 0.03, vitamin B6 0.70 vitamin B12 0.002, pantothenic acid 2.63, biotin 0.0065. 3. Colostrum contained much less vitamin B6 and pantothenic acid than mature milk; otherwise, there were only slight changes in composition as lactation progressed. Neither these changes, nor the absolute values, resembled those for human or cow's milk. 4. The average daily secretion of B-vitamins in milk represented less than 10% of the mother's dietary intake; that of folate was less than 0.5% of the mother's dietary intake. 5. Baboon milk was calculated to provide infants with approximately the following quantities of B-vitamins (/d): thiamin 0.06 mg, riboflavin 0.25 mg, nicotinic acid 1.1 mg, folate 10 microgram, vitamin B6 0.25 mg, vitamin B12 0.7 microgram, pantothenic acid 0.9 mg, biotin 2.2 microgram.

Animals↗