Biomedical subjects

K G Taylor

Publications and source records attributed to K G Taylor.

At least 37 records · Page 2Linked to original sources

PubMed1990

The work of a lipid clinic: an audit of performance.

An audit of the work of a lipid clinic revealed the need to promote awareness of the problem of hypercholesterolaemia, particularly among the ethnic minority groups. Significant reductions in serum lipid levels and blood pressure were achieved, though target levels were reached in only 40 per cent of patients. Efforts to encourage weight reduction among the obese and to discourage smoking had limited success. The establishment of a lipid clinic ensures ready access to paramedical advice and permits effective treatment of hyperlipidaemia and other coronary risk factors. Such a service costs approximately 500 pounds per patients per year.

England↗

PubMed1989

Inhibition by maltose, isomaltose, and nigerose of the synthesis of high-molecular-weight D-glucans by the D-glucosyltransferases of Streptococcus sobrinus.

Two D-glucosyltransferases are produced by Streptococcus sobrinus C211. One (GTF-S) catalyzes the conversion of sucrose into soluble alpha-(1----6)-linked alpha-(1----3)-branched D-glucans, and the other (GTF-I), of sucrose into alpha-(1----3)-linked alpha-(1----6)-branched D-glucans. These enzymes were studied by using maltose, isomaltose, and nigerose as inhibitors. Maltose and isomaltose were found to be competitive inhibitors of GTF-S, whereas nigerose has no effect on GTF-S activity. The Ki values for maltose and isomaltose were determined to be 11 and 15mM, respectively. Maltose, isomaltose, and nigerose competitively inhibit GTF-I. The Ki values for these inhibitors were found to be approximately 0.8, 2.5, and 15mM, respectively. The inhibitory properties of each disaccharide are interpreted in terms of conformational comparisons with sucrose.

Carbohydrate Conformation↗

PubMed1989

Sodium restriction and blood pressure in hypertensive type II diabetics: randomised blind controlled and crossover studies of moderate sodium restriction and sodium supplementation.

OBJECTIVE: To determine the effect of moderate dietary sodium restriction on the hypertension of non-insulin-dependent (type II) diabetes. DESIGN: Randomised parallel controlled study of moderate sodium restriction for three months compared with usual diabetic diet, followed by randomised double blind crossover trial of sustained release preparation of sodium for one month versus placebo for one month in patients continuing with sodium restriction. SETTING: Patients attending diabetic outpatient clinic of city hospital. PATIENTS: Thirty four patients with established type II diabetes complicated by mild hypertension (systolic blood pressure greater than 160 mm Hg or diastolic pressure greater than 95 mm Hg on three consecutive occasions). Patients already taking antihypertensive agents (but not diuretics) not barred from study provided that criteria for mild hypertension still met. Conditions precluding patients from study were diabetic or hypertensive nephropathy, cardiac failure, and pregnancy. INTERVENTIONS: After run in phase with recordings at seven weeks, three weeks, and time zero patients were allocated at random to receive moderate dietary sodium restriction for three months (n = 17) or to continue with usual diabetic diet. Subsequently nine patients in sodium restriction group continued with regimen for a further two months, during which they completed a randomised double blind crossover trial of sustained release preparation of sodium (Slow Sodium 80 mmol daily) for one month versus matching placebo for one month. END POINT: Reduction in blood pressure in type II diabetics with mild hypertension. MEASUREMENTS AND MAIN RESULTS: Supine and erect blood pressure, body weight, and 24 hour urinary sodium and potassium excretion measured monthly during parallel group and double blind crossover studies. After parallel group study sodium restriction group showed significant reduction in systolic blood pressure (supine 19.2 mm Hg, erect 21.4 mm Hg; p less than 0.001) and mean daily urinary sodium excretion (mean reduction 60 mmol/24 h). There were no appreciable changes in weight, diabetic control, or diastolic pressure. No significant changes occurred in controls. In double blind crossover study mean supine systolic blood pressure rose significantly (p less than 0.005) during sodium supplementation (to 171 mm Hg) compared with value after three months of sodium restriction alone (159.9 mm Hg) and after one month of placebo (161.8 mm Hg). CONCLUSIONS: Moderate dietary restriction of sodium has a definite hypotensive effect, which may be useful in mild hypertension of type II diabetes.

Clinical Trials as Topic↗

PubMed1989

Glucosyltransferases of Streptococcus sobrinus C211 are both stimulated and inhibited by hydrogen peroxide.

There are 2 glucosyltransferases (GTF) produced by Streptococcus sobrinus C211. One enzyme, GTF-S, produces a water-soluble glucan that is a-1,6-linked, with short a-1,3 branches, and the other enzyme, GTF-I, produces a water-insoluble glucan that is a-1,3-linked with a-1,6 branches. Hydrogen peroxide was found not only to be a potent inhibitor of GTF activity, but also a stimulator of GTF activity when employed at relatively low concentrations. At 0.88 M, H2O2 completely inhibited insoluble glucan synthesis, whereas at a 0.29 M concentration, H2O2 enhanced synthesis of the same glucan. Soluble glucan synthesis was also inhibited by H2O2 at 1.47 M. Low concentrations of hydrogen peroxide with GTF-S, however, caused the enzyme to convert from soluble glucan production to insoluble glucan production. 13C-Nuclear magnetic resonance spectra of glucans produced by peroxide-treated GTF confirmed that the production of a-1,3 linked glucans was increased with H2O2-treated GTF-S.

Glucans↗

PubMed1989

Randomised blind controlled trial of a high fibre, low fat and low sodium dietary regimen in mild essential hypertension.

Thirty-four patients with essential hypertension were allocated, in a controlled trial, to a treatment diet of high fibre, low fat and low sodium composition, or to a control diet by the hospital dietitian. Clinical observations were made by a separate 'blinded' nursing sister. After three months treatment, the modified diet-treated group showed a significant reduction in mean systolic (169.4 +/- 23.4 to 150.6 +/- 16.1 mmHg) and diastolic blood pressure (101.5 +/- 7.3 to 89.4 +/- 6.8 mmHg), accompanied by significant reductions in urinary sodium excretion (140.4 +/- 34.6 to 93.7 +/- 44 mmol/day) and weight (73.1 +/- 10 to 71.2 +/- 8.4 kg). The changes in control were; systolic 171.2 +/- 14.1 to 162.1 +/- 19.5 mmHg and diastolic pressure 97.2 +/- 10.8 to 91.7 +/- 9.7 mmHg. The mean differences in reductions between treated and control were 8.8 mmHg Systolic (95% confidence intervals: -2.6 to 21.2 mmHg) and 7.0 mmHg diastolic blood pressure (95% confidence intervals: 0.4 to 14.4 mmHg). The number of patients with normal blood pressure in the diet treated group at three months was double that in the control (eleven versus five). No relationships were shown between blood pressure changes and those of weight or urinary sodium excretion during the trial. The findings in this study are broadly in agreement with similar ones in essential hypertension and suggest that this form of dietary regimen has a clinically worthwhile hypotensive effect and this should be readily achievable in routine clinical practice.

Aged↗

PubMed1988

(Z,Z)-1,1'-(1,6-hexanediyl)bis(2-phenyldiazene) 2,2'-dioxide: a bis(azoxy) compound.

C18H22N4O2, Mr = 326.40, orthorhombic, Pbca, a = 19.475 (10), b = 10.435 (20), c = 8.762 (20) A, V = 1780.6 A3, Z = 4, Dx = 1.22 g cm-3, lambda(Mo K alpha) = 0.7107 A, mu = 0.76 cm-1, F(000) = 696, room temperature, 1564 reflections averaged from two octants, R = 0.044, wR = 0.050 for 669 observed reflections with I greater than sigma(I). The molecule has inversion symmetry and is nearly planar. The azoxy group is trans-substituted. Molecular packing is in herringbone-type layers.

Azo Compounds↗

PubMed1988

Glucan-binding factor in saliva.

High-molecular-weight polymers of alpha-1,6-linked D-glucans are insoluble in alcohol solutions. Whole, but not parotid, saliva prevented the precipitation of D-glucans by 80% (vol/vol) ethanol, showing that the whole saliva contained a factor which complexed with the glucan to render it alcohol soluble. The glucan-binding factor was retained on a column of Sephacryl S-200 which had been preequilibrated with 80% ethanol. The factor was then eluted with water. Passive hemagglutination assays revealed that the glucan-binding factor could sensitize erythrocytes to agglutination with anti-poly(glycerolphosphate), suggesting that the active glucan-binding component with lipoteichoic acid. The glucan-solubilizing factor was resistant to heat (100 degrees C), proteases, sialidase, lysozyme, lactoperoxidase, trichloroacetic acid, and Triton X-100. When sucrose was added to saliva, a suspension of Streptococcus cricetus AHT, or a suspension of Streptococcus sanguis 10556, relatively large amounts of glucan-binding factor were released in a soluble form. In addition, penicillin G caused the release of the glucan-solubilizing component from a suspension of S. cricetus AHT. It is suggested that whole saliva contains a component, tentatively identified as lipoteichoic acid, which can complex with glucans in a relatively hydrophobic solvent. This type of complex formation may be important in the adhesion of oral streptococci to saliva-coated surfaces.

Glucans↗

PubMed1988

Specificity of the glucan-binding lectin of Streptococcus cricetus.

The specificity of the glucan-binding lectin (GBL) of Streptococcus cricetus AHT was determined. Examination of the kinetics of aggregation of cell suspensions with glucans containing various percentages of alpha-1,6, alpha-1,4, alpha-1,3, and alpha-1,2 anomeric linkages revealed that only glucans with at least 80% alpha-1,6 linkages promoted strong aggregation. Moreover, only linear glucans with molecular weights greater than 5 X 10(5) were capable of causing rapid aggregation of the bacteria. The lectin was observed to be present on S. cricetus strains, on Streptococcus sobrinus, and on several Streptococcus mutants strains. Preincubation of suspensions of S. cricetus AHT with glucan T10 (molecular weight of 10,000) before the addition of high-molecular-weight glucan resulted in competitive inhibition in a concentration-dependent manner. Inhibition was achieved also with isomaltopentaose, isomaltohexaose, and isomaltooctaose, but at higher concentrations than glucan T10. In contrast, no inhibition was observed with maltoheptaose, providing additional evidence for the specificity of GBL. Treatment of suspensions of S. cricetus AHT with trypsin before and after aggregation with high-molecular-weight glucan revealed a substantial level of protection of GBL when in a bound state. Collectively, these results indicated that GBL has an absolute affinity for glucans rich in alpha-1,6 linkages and possesses an active site which recognizes internal sequences and accommodates isomaltosaccharides of at least nine residues. This unusual specificity may contribute to the colonization of S. cricetus, S. sobrinus, and S. mutans in glucan-containing plaque in the oral cavity.

Agglutination↗

PubMed1988

Expression of the glucan-binding lectin of Streptococcus cricetus requires manganous ion.

Streptococcus cricetus AHT exhibited a requirement for manganese for growth and expression of the glucan-binding lectin. While low concentrations of manganese (0.1 to 10 microM) were able to support growth, higher concentrations (greater than 100 microM) were required for full expression of the glucan-binding lectin. The manganous-aquo ion may be important in cellular adhesion and accumulation processes in dental plaque.

Bacterial Adhesion↗

PubMed1988

The paediatric origins of atherosclerosis.

Cardiovascular disease is the major cause of death in North America and western Europe. The majority of these deaths are due to myocardial or cerebral infarction, atherosclerosis being the principal cause (Report of the Working Group of Arteriosclerosis of the National Heart, Lung, and Blood Institute, 1981). The pathogenesis of atherosclerosis is being elucidated and some predisposing factors defined.

Adult↗

PubMed1987

Role of sialic acid in the kinetics of Streptococcus sanguis adhesion to artificial pellicle.

Evaluation of the kinetics of adhesion of Streptococcus sanguis 10556 to saliva-coated hydroxylapatite revealed that sialic acid played a role in the formation of a stable cell-substratum complex. In a previous paper (M. M. Cowan, K. G. Taylor, and R. J. Doyle, J. Dent. Res. 65:1278-1283, 1986) the adhesion was found to take place in two distinct stages: a reversible equilibrium, probably governed by long-range forces, followed by a transition to higher-affinity binding. In the present study, artificial pellicle was treated with neuraminidase, and kinetic adsorption and desorption experiments with S. sanguis were conducted. The depletion of sialic acid from pellicle decreased the initial adsorption rate constant only slightly. The rate constant describing the initial desorption was unaffected. However, no transition to the second (high-affinity) association occurred. While S. sanguis desorption from control pellicles exhibited two sequential rates, with the second rate being approximately 10 times slower than the first, all desorption from sialo-deficient pellicles occurred at one rate that was equivalent to the initial rate constant for control desorption. The cells did not reach an equilibrium with the sialo-deficient pellicle, even after 6 h. Competing sialic acid did not decrease the rate or extent of adsorption, but desorption occurred to a greater extent when cells had adsorbed in the presence of sialic acid. These data suggest that sialic acid plays little role in the initial association of cell and pellicle but that it is necessary for the transition to high-affinity binding and the concomitant decreased propensity to desorb.

Bacterial Adhesion↗

PubMed1987

Energetics of the initial phase of adhesion of Streptococcus sanguis to hydroxylapatite.

The initial adhesion of Streptococcus sanguis 10556 to artificial salivary pellicle and to bare hydroxylapatite was studied at several temperatures between 18 and 37 degrees C. When the natural logarithms of rate constants for adsorption and desorption were plotted against reciprocal temperatures in Arrhenius plots, curved lines were obtained, indicating that the thermodynamic quantities of enthalpy and entropy of activation were temperature dependent. For the bare hydroxylapatite system, the heat capacity (delta Cp = dH/dT) was large and negative. delta Cp was also negative for adhesion to saliva-coated hydroxylapatite, although its value was lower. Negative heat capacities, when coupled with favorable entropy, are often indicative of either electrostatic or hydrophobic interactions. When electrolyte (100 mM ammonium sulfate) was added to the cell-hydroxylapatite bead mixture, the rate and extent of adhesion were decreased. Addition of nonpolar p-dioxane (10% [vol/vol], final concentration) to the mixture enhanced binding. This suggests that electrostatic linkages participate in the primary adhesion of streptococci to both substrata. The strongly positive entropy values and the lesser temperature dependence of the saliva-coated hydroxylapatite system suggest that another entropy-driven process is imposed on the electrostatic linkages. This supports a role for hydrophobicity, suggesting that a combination of electrostatic and hydrophobic forces mediate the initial adhesion of S. sanguis to the salivary pellicle.

Ammonium Sulfate↗

PubMed1986

Kinetic analysis of Streptococcus sanguis adhesion to artificial pellicle.

Studies of equilibria between Streptococcus sanguis and artificial pellicle have suggested that there are multiple binding sites for the organism. In the present study, adhesion of S. sanguis to saliva-coated hydroxylapatite was examined by means of kinetic methods. Cell-pellicle complex formation was measured from initiation of binding to equilibrium. Rate constants were calculated for forward reactions (adsorption) and reverse reactions (desorption). Initial binding obeyed reversible, first-order kinetics, whereas desorption of bound cells followed biphasic kinetics. Initial desorption proceeded approximately ten times faster than the slower second rate. The results are consistent with the mechanism C + P reversible CP* in equilibrium with CP in which CP* represents the reversible equilibrium that shifts at a discrete rate to the high-affinity CP state. Thus, the biphasic binding behavior that has been previously deduced from equilibrium studies may be attributed to a time-dependent shift from close apposition to pellicle, stabilized by low-specificity forces, to a higher-affinity binding.

Adhesiveness↗

PubMed1986

High fibre, low sodium and low fat diet in white and black type 2 diabetics with mild hypertension.

White and black mildly hypertensive Type 2 diabetics were given an intended diet high in unrefined carbohydrate (50% daily energy) and fibre (40-45 g/day) while low in fat (25% daily energy) and sodium (60-80 mmol/day) for 3 months. Both white and black diabetic hypertensive patient groups demonstrated a significant reduction of systolic (p less than 0.01 and p less than 0.001 respectively) and diastolic blood pressure (p less than 0.001 and p less than 0.01 respectively). This was accompanied by a significant reduction of daily urine sodium excretion, urine sodium: potassium ratio, weight and glycosylated haemoglobin in both groups. Only whites had a significant reduction of serum triglyceride level (p less than 0.05) although blacks showed similar trends. Compliance to the dietary regimen, assessed by a trends. Compliance to the dietary regimen, assessed by a scoring method appeared comparable in both groups. These data suggest this modified dietary regimen might be considered an attractive alternative to conventional antihypertensive drug therapy in mildly hypertensive Type 2 diabetic black as well as white patients.

Black People↗

PubMed1985

Prevalence of hypertension in white, black and Asian diabetics in a district hospital diabetic clinic.

In a District General Hospital Diabetic Clinic 40.0% of a random sample of diabetics under the age of 65 years of age were hypertensive. Black patients (48.9%) had greater (p less than 0.05) prevalence of hypertension than Whites (37.5%) and Asians (35.4%). Hypertension was more prevalent in females (49.1%) than males (33.0%) (p less than 0.001) in each ethnic group except Asians, and patients not receiving insulin had greater prevalence (45.6%) than those on insulin (30.7%) (p less than 0.001), except black diabetics where the reverse was found. There was a positive relationship between age and systolic (p less than 0.00001) and diastolic blood pressure (p less than 0.00001) and a negative association between duration of diabetes and diastolic blood pressure (p less than 0.004) on multiple regression analysis but no relationship was noted between blood pressure and either weight or blood glucose. Forty-six percent of all hypertensives were receiving conventional anti-hypertensive drug therapy; 38.7% were normotensive with similar results in each ethnic group and between the sexes. Isolated systolic hypertension was the commonest form of hypertension (48.3%) with isolated diastolic hypertension (4.9%) the rarest. These findings were observed regardless of the ethnic group or gender. Although in the majority of cases hypertension was mild these data confirm the importance of routine blood pressure measurement in diabetic patients.

Cross-Sectional Studies↗

PubMed1985

Medical conditions underlying recurrence of retinal vein occlusion.

Seventeen patients with recurrent retinal vein occlusion were investigated for underlying medical conditions and compared with 61 patients with single retinal vein occlusion (26 with central, 35 with branch vein occlusion). The two study groups were comparable for age, sex, and weight. Patients with recurrence had a significantly increased prevalence rate of hypertension (88% versus 48%: p less than 0.01), with a trend to increased hyperlipidaemia (47% versus 33%) compared with patients with a single episode. A significantly raised mean systolic (p less than 0.05) but not diastolic blood pressure was found in patients with recurrence. Other cardiovascular risk factors in patients with recurrence were also found and included lower mean levels of high density lipoprotein (HDL)-cholesterol (p less than 0.02) and the HDL2 subfraction (p less than 0.001), and a significantly increased proportion of patients with regular alcohol intake (p less than 0.01). We conclude that hypertension and hyperlipidaemia with an increase in other cardiovascular risk factors are commonly found in patients with recurrent retinal vein occlusion and may therefore be important aetiological factors. The possible benefits of treatment of these underlying conditions to prevent recurrence need to be assessed in well designed prospective studies.

Aged↗

PubMed1985

Trypsin-susceptible cell surface characteristics of Streptococcus sanguis.

The adherence of Streptococcus sanguis to saliva-coated hydroxylapatite was markedly reduced by treatment of the cells with trypsin. In Scatchard plots of adherence data, protease-treated S. sanguis did not exhibit the characteristic positive slopes, suggesting that trypsin prevented cooperative interactions between the cells and artificial pellicle. Trypsin also reduced the tendency of S. sanguis to bind to hexadecane and to octyl-Sepharose. When sodium dodecyl sulfate was used to elute S. sanguis from columns of octyl-Sepharose, it was observed that the elution profiles of trypsin-treated cells were more complex than those of control cells. Water and salts were incapable of removing the cells from octyl-Sepharose. The results suggest that adherence to saliva-coated hydroxylapatite, binding to hexadecane and to octyl-Sepharose depend on trypsin-susceptible cell surface molecules.

Adhesiveness↗

PubMed1984

A controlled trial of a high fibre, low fat and low sodium diet for mild hypertension in Type 2 (non-insulin-dependent) diabetic patients.

Fifty hypertensive Type 2 (non-insulin-dependent) diabetic patients were allocated, in a controlled trial, to a treatment diet of high fibre, low fat and low sodium composition, or to a control diet by the hospital dietitian. After 3 months treatment, the modified diet-treated group showed a highly significant reduction in mean systolic (180.5 +/- 19.0 to 165.0 +/- 20.7 mmHg) and diastolic blood pressure (96.6 +/- 9.3 to 88.0 +/- 10.5 mmHg), accompanied by significant reductions in urinary sodium excretion (183.0 +/- 62.1 to 121.7 +/- 65.8 mmol/day) glycosylated haemoglobin (12.4 +/- 3.1 to 10.5 +/- 2.9%), weight (74.6 +/- 13.5 to 71.7 +/- 12.1 kg) and serum triglyceride levels (p less than 0.05). The mean values of diastolic pressure (p less than 0.01), urinary sodium/potassium ratio (p less than 0.001), urinary potassium (p less than 0.01) was significantly reduced at 3 months compared to control. No changes in serum HDL-cholesterol levels were observed. The number of patients with normal blood pressure at 3 months was greater in the modified diet-treated group (ten versus five). Treatment of mild hypertension in diabetic subjects with this form of dietary regimen has a hypotensive response, with improvement in glycaemic control and no side effects. This modified diet may be an attractive alternative to anti-hypertensive drug therapy as a first line treatment.

Blood Glucose↗