Search PubMed⌕ Search

Biomedical subjects

N Wilson

Publications and source records attributed to N Wilson.

At least 217 records · Page 12Linked to original sources
PubMed1985

Evaluation of an elliptical area technique for calculating mitral blood flow by Doppler echocardiography.

To evaluate a method for measuring blood flow through the mitral valve 18 normal subjects and 19 patients with cardiac disease in whom mitral and aortic blood flows were identical were studied. Initially the mitral ring area was planimetered from the echocardiographic image, but the results of area calculation using the mathematical formula for the area of an ellipse were found to approximate to within 8% of the planimetered result in most cases. The formula was therefore used if the ring appeared elliptical on the cross sectional echo image, and other shapes were planimetered. Mitral velocity, aligned with flow in three planes, was recorded just distal to the ring. Mitral flow calculated using the elliptical technique correlated closely with flow measured in the ascending aorta by the Doppler technique and also with systemic flow measured by the Fick method at cardiac catheterisation in 10 patients. The mitral flow technique that assumed a circular orifice correlated almost as well with Doppler aortic flow and with Fick flow but overestimated flow by a mean of 1446 ml, whereas the elliptical method had a mean error of only 138 ml. Both methods correlated well with standards, but the elliptical method was easy to apply and gave a better correlation with comparison reference values.

Adolescent↗
PubMed1985

Plasma vasopressin during increases and decreases in blood volume in anaesthetized dogs.

In chloralose-anaesthetized dogs, plasma vasopressin concentration was measured by radioimmunoassay during step changes in blood volume of 4 mL/kg over a range of blood volume from +20 to -12 mL/kg. Blood volume was both increased and decreased over this range. There was a logarithmic relationship between blood volume and plasma vasopressin concentration over the range of blood volume examined. There was also a logarithmic relationship between blood volume and mean left atrial pressure. Linear regression between the natural logarithm of plasma vasopressin concentration and mean arterial pressure, heart rate, and mean left atrial pressure gave the highest correlation coefficient (r = 0.94) between vasopressin and mean arterial pressure. The results support the hypothesis that there are sensitive mechanisms controlling the release of vasopressin in response to changes in blood volume. Observations were also made of changes in atrial pressure and activity of left atrial receptors during changes in blood volume over the same range. The results suggest that changes in atrial receptor activity are unlikely to be the major cause of the large increases in plasma vasopressin concentration associated with hypovolemia.

Anesthesia↗
PubMed1985

Release of atrial natriuretic peptide by atrial distension.

A heterologous radioimmunoassay was used to measure the concentration of immunoreactive atrial natriuretic peptide (iANP) in plasma from the femoral artery of eight chloralose anaesthetized dogs. Mitral obstruction which increased left atrial pressure by 11 cmH2O increased plasma iANP from 97 +/- 10.3 (mean +/- SE) to 135 +/- 14.3 pg/mL. Pulmonary vein distension increased heart rate but did not increase plasma iANP. Bilateral cervical vagotomy and administration of atenolol (2 mg/kg) did not prevent the increase in iANP with mitral obstruction. Samples of blood from the coronary sinus had plasma iANP significantly higher than simultaneous samples from the femoral artery confirming the cardiac origin of the iANP. Release of iANP depends on direct stretch of the atrium rather than on a reflex involving left atrial receptors.

Animals↗
PubMed1985

Autoradiographic localization of binding sites for atrial natriuretic factor.

The distribution of atrial natriuretic factor (ANF) binding sites in Wistar rat tissues, as well as tissues from other species was studied. Using autoradiography of slide mounted tissue sections incubated with 125I-labelled ANF, high densities of binding sites were found in the renal glomeruli and papilla, aortic smooth muscle, iliac vein, choroid plexus, anterior pituitary, lung, and adrenal zona glomerulosa. Results from renal, aortic, adrenal, and lung tissues from spontaneously hypertensive rats did not differ from those of Wistar rats. Binding sites were also observed in guinea pig glomeruli, renal medulla, and aorta as well as in the rabbit aorta.

Adrenal Cortex↗
PubMed1984

The relationship between plasma vasopressin concentration and urinary excretion during left atrial distension in anaesthetized dogs.

The relationship between the changes in plasma vasopressin (AVP) concentration and urinary concentration during left atrial distension has been examined in 12 anaesthetized dogs. Left atrial pressure was increased by 1.2 kPa for 30 min. Plasma AVP concentration (radioimmunoassay) was decreased 5 min after the start of atrial distension and was increased again 5 min after the end of distension. The average decrease was about 50% from a mean of 6.4 +/- 2.4 pg X ml-1 (SE). Urine osmolality decreased more slowly reaching its lowest value in the first 10 min after removal of atrial distension. In contrast sodium excretion increased immediately upon atrial distension. Because of the difference in the time course of the changes in plasma AVP and urine osmolality, plasma AVP was compared with the urine osmolality in samples collected 15 min after the plasma samples. At any plasma AVP concentration there was a wide variation in urine osmolality between dogs, but in any one dog there was clear relationship between plasma AVP and urine osmolality. The results support the view that the diuretic response to left atrial distension is due, at least in part to decreases in plasma AVP concentration. They also show that a stimulus arising from increased left atrial pressure influences the relationship between plasma osmolality and plasma AVP concentration.

Anesthesia, General↗
PubMed1984

Junctional epidermolysis bullosa in two siblings: clinical observations, collagen studies and electron microscopy.

Two siblings with junctional epidermolysis bullosa are described: both survived beyond parturition. They were treated with the usual therapeutic doses of phenytoin, dapsone, prednisolone, and zinc supplements without effect. Investigation of the skin of one of the patients showed that his fibroblasts, collagen synthesis and collagenase levels were normal. In view of the normality of the collagenase levels, it is probably not surprising that phenytoin was ineffective. Electron microscopy demonstrated junctional cleavage without pathology in the dermis itself: abnormal hemidesmosomes were seen as described previously, though it is suggested that this is not the primary abnormality which results in the disease process.

Child, Preschool↗
PubMed1984

Oral tartrazine challenge in childhood asthma: effect on bronchial reactivity.

Ten asthmatic children who gave a history of cough or wheeze after orange drinks, were tested for tartrazine sensitivity. On separate days, either oral tartrazine (1 mg) or a placebo capsule were administered double blind. Bronchial reactivity was measured before, 30 and 60 min after ingestion by means of a histamine-inhalation challenge test. There was no change in baseline lung function after tartrazine, but histamine sensitivity (PC20) increased significantly in four of the children. No response was obtained to a larger dose of tartrazine (10 mg) in four of the non-responders. Alteration in the bronchial reactivity after an oral challenge, appears to be a sensitive means of detecting tartrazine sensitivity.

Adolescent↗
PubMed1984

Digital subtraction angiography in infants and children with congenital heart disease.

Digital subtraction angiography was used as the sole imaging technique in 95 infants and children aged 13 hours to 16 years undergoing cardiac catheterisation for the investigation of congenital heart disease. Injections of diluted contrast medium were made selectively at central sites, and the images were obtained using continuous image intensification fluoroscopy at either 32.25 nC/kg/s (125 microR /s) or 129 nC/kg/s (500 microR /s). In all cases images adequate for diagnosis and management were obtained with appreciably less contrast medium and a lower radiation dose than in a comparable group of patients using conventional biplane cineangiography. Thus digital subtraction angiography is a viable alternative to biplane cineangiography for children with congenital heart disease.

Adolescent↗
PubMed1984

Valvar stenosis in truncus arteriosus.

Twenty three morphological specimens of truncus arteriosus were examined for evidence of stenosis of the semilunar valve. One third showed good evidence of stenosis as judged by careful measurement of the valve orifice, the valve ring, and the maximum diameter of the truncus. Correlation with measured pressure gradients was poor, but angiography and cross sectional echocardiography were better predictors of stenosis. Stenosis was invariably associated with cusp dysplasia and was more common in valves with two or four cusps.

Angiocardiography↗
PubMed1984

Pulmonary artery velocity patterns in ductus arteriosus.

In 12 patients with ductus arteriosus a characteristic velocity pattern in the pulmonary artery was identified using pulsed Doppler echocardiography. This pattern, which was absent in 52 normal control subjects and 200 consecutive patients with cardiac lesions other than ductus, consisted of a pandiastolic velocity directed away from the transducer. This pattern is thought to represent the diastolic component of flow into the pulmonary tree which occurs as a result of the left to right shunt.

Adolescent↗
PubMed1984

Left ventricular bands. A normal anatomical feature.

Discrete delicate fibromuscular structures crossing the cavity of the left ventricle were identified on morphological examination in 329 (48%) of 686 hearts from patients of all ages with congenital heart disease, acquired heart disease, or normal hearts. These structures were also present in 151 (95%) of 159 hearts from animals of six species. Cross sectional echocardiographic findings compatible with these structures were obtained in 39 (21.7%) of 179 children reviewed retrospectively and in three of 800 (0.4%) adults studied prospectively. These structures appear to be a normal anatomical finding.

Adult↗
PubMed1984

Bronchial responsiveness to hyperventilation in children with asthma: inhibition by ipratropium bromide.

Isocapnic hyperventilation dose response curves were constructed for 11 asthmatic children before and after pretreatment with placebo or ipratropium bromide, 40-1500 micrograms given by inhalation, on three separate days. The response before and after placebo was highly reproducible (within subject coefficient of variation 7.5%, 18%, and 22% for intervals of two hours, within two weeks, and over two weeks). It was independent of baseline lung function. Complete protection against hyperventilation induced asthma was achieved by ipratropium bromide 40 micrograms in six children and by 200 micrograms or more in a further four. The remaining child was unaffected by any dose of ipratropium up to 1500 micrograms. The dose of ipratropium required for protection was better related to the subjects' requirement for regular medication than to their sensitivity to hyperventilation or baseline lung function.

Adolescent↗
PubMed1983

Neurohypophysial peptides and the hippocampus. I. Vasopressin immunoreactivity in the rat hippocampus.

Immunocytochemical studies have demonstrated that nerve fibres containing immunoreactive vasopressin project to many areas of the central nervous system. In the present investigation, the presence of immunoreactive arginine vasopressin (IR-AVP) in the hippocampus of Wistar rats was confirmed by radioimmunoassay. The vasopressin content of the dorsal hippocampus was 30.3 +/- 7.3 pg IR-AVP/mg soluble protein (mean +/- SEM, n = 9) and that of the ventral hippocampus was 81.4 +/- 8.3 pg IR-AVP/mg soluble protein (n = 9), while tissue from the cerebral cortex contained no detectable vasopressin. That the immunoreactivity was due to vasopressin was confirmed by its absence in hippocampal or cortical tissue from homozygous Brattleboro rats, which are genetically unable to synthesize vasopressin.

Animals↗
PubMed1983

Neurohypophysial peptides and the hippocampus. II. Excitation of rat hippocampal neurones by oxytocin and vasopressin applied in vitro.

Neurohypophysial peptides were applied by superfusion to rat hippocampal slices. The peptides, arginine vasopressin, lysine vasopressin, arginine vasotocin and oxytocin, increased the activity of 88% of spontaneously active cells in the CA1 region and induced firing in many neurones that were not spontaneously active. The peptide sensitive cells appeared to be pyramidal cells rather than interneurones. The four peptides were found to be of roughly equivalent potency, producing a reversible, dose-dependent response in the range 10(-9) to 10(-6)M. Most of the cells were tested with more than one peptide and were always found to respond either to all or to none of them. The analogue [7-glycine]oxytocin and the deamino, dicarba derivatives of oxytocin and vasopressin were about as active as the parent compounds, but the oxytocin fragment prolyl-leucyl-glycinamide had no effect, and desglycinamide vasopressin was extremely weak. Responses to the peptides could be blocked by "specific" antagonists. The results suggest that all of the peptides are acting upon a single class of receptor.

Animals↗
PubMed1983

Randomized controlled trial of physiotherapy for postoperative pulmonary complications.

A prospective randomized controlled trial was conducted in patients undergoing elective cholecystectomy to assess the value of routine chest physiotherapy. One hundred and two patients entered the study: 47 patients developed no pulmonary complications, 29 had pulmonary atelectasis and a further 26 developed chest infection. The pattern of changes in arterial oxygen tension in the period after operation supported the clinical allocation of the patients. Of 51 patients not receiving physiotherapy, 11 developed atelectasis and 19 chest infection. Of 51 treated patients, 18 developed atelectasis and seven chest infection. Routine prophylactic postoperative chest physiotherapy decreased significantly the frequency of chest infection (P less than 0.02).

Adult↗