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Biomedical subjects

R Sutton

Publications and source records attributed to R Sutton.

At least 109 records · Page 6Linked to original sources
PubMed1985

Occurrence of haploid and haploid/diploid mosaic embryos in untreated and androstenedione-immune Australian Merino sheep.

Chromosome counts were obtained from 73 out of 177 (41%) early cleavage-stage Merino embryos. A further 13 embryos were classified as probably diploid. Chromosome aberrations were found in 8 (11%) embryos, one of which was aneuploid and the remainder (9.6%) had euploid abnormalities. If the probable diploid embryos are included, the incidence of euploid aberrations falls to 8.1%. Of the abnormal embryos there was one aneuploid with 2N = 55, two haploids, four haploid/diploid mosaics and one zygote with 4 haploid metaphase plates. Two additional zygotes had 4 interphase pronuclei. Four of the euploid abnormalities were attributable to the entry of two or more spermatozoa and therefore polyspermy is the largest single factor leading to chromosomally aberrant embryos in this population of Merino ewes.

Androstenedione↗
PubMed1984

Allergen discs prepared from nitrocellulose: detection of IgE binding to soluble and insoluble allergens.

Nitrocellulose discs, 6 mm in diameter, are suggested as an alternative to cyanogen bromide-activated paper for the coupling of allergens in radio- or enzyme-linked assays to estimate allergen-specific IgE in serum. The preparation of allergen discs with nitrocellulose is simple, involving 3 steps: (a) drying allergen extract onto disc, (b) soaking discs in a 3% solution of bovine serum albumin, and (c) washing out the buffer. Very similar results (r = 0.94) were obtained using either paper or nitrocellulose discs for radioallergosorbent testing of sera from 15 bakers using allergens from mites, ryegrass pollen or wheat grain. The amount of protein (as radiolabelled albumin) actually bound to either type of disc or microtitre trays was similar, and low (5% of the protein applied for each media). However, when the protein was applied to nitrocellulose in 1% KOH up to 70% of it was bound. This solvent permitted better evaluation of IgE binding to insoluble allergens such as glutenin, which proved to be the most allergenic wheat-grain fraction tested by this method for a group of 9 bakers.

Allergens↗
PubMed1984

Mechanism of polyuria and natriuresis in atrioventricular nodal tachycardia.

A woman with tachycardia associated with polyuria was investigated. Electrophysiological analysis showed that the tachycardia was an atrioventricular nodal re-entrant tachycardia. Programmed stimulation was then used to provoke and sustain the tachycardia for 40 minutes. Polyuria, with an appreciable increase in free water clearance, was observed. This was associated with reduction in plasma and urinary arginine vasopressin concentrations. Appreciable natriuresis also developed. These results support the hypothesis that the polyuria with increased free water clearance and the natriuresis occurring during sustained tachycardia in man are due to inhibition of secretion of vasopressin and the release of natriuretic factor.

Arginine Vasopressin↗
PubMed1984

The nature of the reaction of an essential tyrosine residue of bovine heart mitochondrial ATPase with 4-chloro-7-nitrobenzofurazan and related compounds.

Bovine heart mitochondrial ATPase is inhibited after covalent modification with 4-chloro-7-nitrobenzofuroxan. The kinetics of the reaction are indistinguishable from those for the reaction of an essential tyrosine residue of the ATPase with 4-chloro-7-nitrobenzofurazan that have been described previously [Ferguson et al. (1975) Eur. J. Biochem. 54, 117-126]. 4-Fluoro-7-nitrobenzofurazan inhibits the ATPase with a pseudo-first-order rate constant that is tenfold greater than that for 4-chloro-7-nitrobenzofurazan. These data indicate that the rate-limiting step for reaction of the enzyme with these reagents is formation of a Meisenheimer complex at the C-4 position and that the modified tyrosine is probably on the surface of the protein. No evidence was found for more complex patterns of reactivity of 4-chloro-7-nitrobenzofurazan and its analogues. Both ammonium 4-chloro-7-sulphobenzofurazan and ammonium 4-fluoro-7-sulphobenzofurazan fail to react with the ATPase. The utility of these reagents as alternatives to the nitro derivatives may be limited owing to their slow reaction rates. After modification on tyrosine by 4-chloro-7-nitrobenzofurazan, the nitrobenzofurazan group can be transferred by an intramolecular process to lysine [Ferguson et al. (1975) Eur. J. Biochem. 54, 127-133]. ATPase with the lysine thus modified is shown to be reactive towards 4-chloro-7-nitrobenzofurazan in a manner indistinguishable from the native enzyme. This indicates that the intramolecular transfer occurs at sufficient distance to avoid steric hindrance to the second reaction, and that the lysine does not participate in a neighbouring group effect to enhance the reactivity of the tyrosine.

4-Chloro-7-nitrobenzofurazan↗
PubMed1984

Antigens and allergens from the common house dust mite Dermatophagoides pteronyssinus. Part I. Demonstration of multiple allergens by immunochemical and biologic analyses.

The complexity of a highly allergenic water-soluble extract of the common house dust mite Dermatophagoides pteronyssinus has been investigated by use of the preparative fractionation techniques of ultrafiltration, gel permeation chromatography, and isoelectric focusing, and the allergenic properties of the resultant fractions are assessed by skin prick tests, RAST, and a histamine-release assay. In addition, two analytical approaches were used to identify allergens-radioimmunoelectrophoresis and a new technique for detecting IgE-binding proteins separated by isoelectric focusing and transferred onto a nitrocellulose membrane by transverse electrophoresis. These various techniques for allergen detection revealed differences in the number and distribution of allergens in the crude mite extract. The data obtained are consistent with the conclusion that allergenic activity of D. pteronyssinus extracts is due to the existence of a number of antigenically distinct allergens and not due to a single, major allergen.

Allergens↗
PubMed1984

Arrhythmias in pacing.

The spectrum of cardiac arrhythmias that may be encountered in paced patients is vast; as multiprogrammable and dual-chamber pacemakers have become more sophisticated, the problems of electrocardiographic interpretation have multiplied. The arrhythmias may be broadly classified as follows: those due to abnormal functioning of the device, those due to normal functioning of the device, and those due to the interaction of the pacemaker with a spontaneous arrhythmia occurring in the patient.

Arrhythmias, Cardiac↗
PubMed1984

A scientific evaluation of the carotid sinus syndrome.

Assessment of the carotid sinus baroreceptor control of pulse interval has been made, by means of neck suction, in 10 patients with a clinical diagnosis of the carotid sinus syndrome (CSS). Results have been compared with 16 age-matched control patients. The mean gain in the CSS patients was 11.64 +/- 2.51 ms . mmHg-1, whereas the mean gain in the control patients was 3.61 +/- 0.68 ms . mmHg-1 (p less than 0.02). There was a significant correlation (p less than 0.01) between the degree of cardiac slowing, following carotid sinus massage, and the gain, following neck suction, in the CSS patients. Abnormality of the carotid sinus baroreceptor control of heart rate is confirmed in these patients and neck suction is an useful method of investigation of this syndrome.

Aged↗
PubMed1984

Baroreflex sensitivity measured by the phenylephrine pressor test in patients with carotid sinus and sick sinus syndromes.

Baroreflex sensitivity was measured by the heart rate response to the transient rise in blood pressure induced by phenylephrine, in 11 patients with carotid sinus syndrome, 6 patients with sick sinus syndrome and nine age and blood pressure matched controls. Patients with carotid sinus syndrome were divided into those with a hypersensitive carotid sinus reflex manifest as sinus arrest (n = 9) and those with a reflex manifest as atrioventricular block (n = 2). The mean gain of the baroreflex sensitivity was significantly increased (p less than 0.001) in patients with carotid syndrome manifest as sinus arrest (12.7 +/- 5.1 ms . mmg-1) compared to that in patients with sick sinus syndrome (3.8 +/- 2.6 ms . mmHg-1) and controls (4.2 +/- 2.1 ms . mmHg-1). Patients with carotid sinus syndrome manifest as atrioventricular block did not have increased baroreflex sensitivity measured by their sinus node response (2.1 +/- 0.5 ms . mmHg-1). There was significant correlation (p less than 0.001) between the corrected carotid sinus inhibitory response to carotid sinus massage and the measurement of baroreflex sensitivity in the carotid sinus syndrome patients. Patients with carotid sinus syndrome manifest as reflex sinus arrest have an increased gain in baroreflex sensitivity for their age, which is not seen in patients with symptomatic sinoatrial disease. This study provides further evidence of a different mechanism of bradycardiac symptoms in patients with carotid sinus and sick sinus syndromes.

Aged↗
PubMed1984

The diversity of allergens involved in bakers' asthma.

Sera from 35 individuals with suspected allergies to inhaled flour were screened for the presence of immunoglobulin E (IgE) specific for wheat-flour proteins. Sera from nine asthmatic bakers with high wheat RAST scores were selected for further study with the aim of purifying the allergen(s) involved in bakers' asthma and related conditions. However, each of the different techniques applied--ion exchange chromatography, preparative isoelectric focusing and the electrophoretic transfer, or 'Western blotting' technique, showed that serum IgE from different individuals have markedly different specificities and bind to numerous wheat proteins. When three purified wheat proteins were tested--wheat germ agglutinin; a fraction purified using a concanavalin-A affinity column and a putative trypsin inhibitor--all were identified as allergens for some but not all of the allergic bakers.

Allergens↗
PubMed1984

Effects of alpha-flupenthixol and naloxone on CRF-induced locomotor activation.

Corticotropin-releasing factor injected intracerebroventricularly in a dose of 1 microgram produced a prolonged locomotor activation (3 h) in rats previously habituated to the test cage environment. This activation was reversed by alpha-flupenthixol (intraperitoneally), a dopamine receptor antagonist, only at cataleptic doses and not at all by naloxone (subcutaneously) in doses of 0.02-5.0 mg/kg. The effective dose 50% (ED50) for the alpha-flupenthixol reversal of locomotor activity induced by corticotropin-releasing factor was 0.13 mg/kg; similar to the 0.14 mg/kg ED50 needed to reverse the locomotor activation produced by caffeine (10 mg/kg s.c.). The ED50 necessary to reverse amphetamine (0.75 mg/kg s.c.) locomotion with this drug was 0.07 mg/kg. The results suggest that the corticotropin-releasing factor acts independently of direct activation of the dopamine or opioid peptide systems.

Animals↗
PubMed1984

Identification of an oestrus-associated glycoprotein in oviducal fluid of the sheep.

Samples of oviducal fluid were collected daily from sheep with indwelling catheters. Fluid samples taken from both oviducts of 2 sheep for 2 cycles during the middle of the breeding season (April/May) (8 sets of data) were compared with 9 sets of data generated from 2 cycles in 3 sheep later in the breeding season (June/July). Around the period of oestrus, the output of oviducal fluid increased to a peak volume of 1.56 +/- 0.35 ml per day (mean +/- s.d.) compared with a mid-cycle volume of 0.49 +/- 0.29 ml. Later in the breeding season, the flow rates were lower, but showed the same trend (0.91 +/- 0.24 ml at the peak and 0.25 +/- 0.18 ml 7 days later). The total amount of protein secreted by the oviduct each day increased 2-4-fold around the time of oestrus, with higher levels in mid-season ewes. When oviducal fluids were fractionated by SDS electrophoresis, a novel glycoprotein, subunit size of Mr 80-90 000 was identified in samples for 3-6 days of each cycle, coinciding with the period of high fluid flow rate. This protein first appeared in the oviducal fluid on the day of oestrus or the following day and it represented 1 of the 2 major glycoproteins in oviducal fluid as assessed by periodic acid-Schiff (PAS) staining. A PAS-positive protein (Mr 80-90 000) was also detected in fluid taken after oestrus on native highly cross-linked gradient gels after electrophoresis at pH 3.1 but not at pH 8.3. Both gradient gel systems showed an increase in high molecular weight material (Mr greater than 10(6] in fluid taken soon after oestrus.

Animals↗
PubMed1983

Characterization of detergent-solubilized adenosine triphosphatase of chromaffin granule membranes.

Purified bovine chromaffin granule membranes contain approximately 24 pmol/mg protein (16 copies per granule) of an F1-like adenosine 5'-triphosphatase, and 340 pmol/mg protein (200 copies per granule) of a low-molecular weight protein which reacts covalently with dicyclohexylcarbodiimide. These co-purify on electrofocusing and exclusion chromatography and are apparently components of a proton-translocating adenosine triphosphatase complex, that is involved in maintaining the high concentration of catecholamines in the granules. The membranes contain another adenosine 5'-triphosphatase, of lower molecular weight, which is sensitive to inhibition by vanadate but relatively insensitive to dicyclohexylcarbodiimide. The function of this enzyme is unknown.

Adenosine Triphosphatases↗
PubMed1983

Sustained improvement in exercise tolerance following physiological cardiac pacing.

Fifty-three patients have received 'physiological' pacemakers, 37 with atrioventricular (AV) block having atrial synchronous units (VAT or VDD) implanted and the remaining 16 patients with both AV block and sick sinus syndrome having 'universal' (DDD) pacemakers. Effort tolerance was assessed by serial bicycle ergometry and in 16 patients direct comparisons between ventricular pacing and atrial synchronous pacing could be made acutely. Physiological pacemakers were found to increase maximum effort tolerance by 43% compared to pre-pacing values (P less than 0.01). The increase was sustained over a mean of 33 months post pacing. The atrial synchronous mode increased maximum effort tolerance by 34% acutely compared to ventricular inhibited pacing. Dual chambered 'physiological' pacemakers represent a significant therapeutic advance over standard ventricular inhibited pacemakers.

Adult↗
PubMed1983

A comparison of once daily atenolol and metoprolol SA in mild to moderate hypertension.

Atenolol 100 mg once daily and metoprolol SA 200 mg once daily were compared in 20 patients with mild to moderate hypertension, in a randomised, double-blind cross-over trial. Blood pressure and heart rate were compared at rest and during maximal exercise on a bicycle ergometer at 2 and 24 h post-dose. Blood pressure control was similar with both drugs, except at 2 h when systolic blood pressure was significantly lower with atenolol. Blood pressure and heart rate were less well controlled at 24 h than at 2 h with both drugs, but the majority of patients were still considered adequately controlled at 24 h. Atenolol and metoprolol SA can be considered equally effective in the treatment of mild to moderate hypertension and can be recommended as a once daily regime.

Adult↗
PubMed1983

Physiological benefits of atrial synchrony in paced patients.

Over a five-year period, hemodynamic exercise capacity studies and a randomized controlled trial have been performed in a total of 50 patients. DVI vs. VVI pacing showed an increase in stroke work index (P less than 0.005) and a fall in left ventricular filling pressure (P less than 0.05) in 17 patients. VDD/DDD pacing vs. VVI showed an exercise capacity benefit in 44 patients (P less than 0.01) including 8 patients with sinus node disease and a lower peak heart rate (P less than 0.02). Maintenance of benefit was also shown of VDD/DDD pacing in the longer term (13 months) vs. acute (P - NS). The controlled trial VDD/DDD vs. VVI showed benefit in shortness of breath (P less than 0.01) and general well being (P less than 0.01). It is concluded that atrial synchronous ventricular pacing (VDD/DDD) is the mode of choice in suitable patients.

Bradycardia↗
PubMed1983

The role of rate hysteresis pacing in the hypersensitive carotid sinus syndrome.

The ability of rate hysteresis programming with the escape interval longer than the automatic interval to reduce the hypotensive response to carotid sinus massage at the onset of ventricular pacing was studied in six patients paced for carotid sinus syndrome. Rate hysteresis significantly reduced this hypotensive response and abolished spontaneous symptoms in two patients and symptoms reproduced by carotid sinus massage in four patients.

Adult↗