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Biomedical subjects

N Wilson

Publications and source records attributed to N Wilson.

At least 199 records · Page 11Linked to original sources
PubMed1987

Extracted and nonextracted atrial natriuretic peptide in rabbits during tachycardia.

The time course of changes in the plasma concentration of immunoreactive atrial natriuretic peptide (iANP) accompanying tachycardia was measured in anesthetized rabbits. In contrast to the hemodynamic changes, which occurred within the 1st min of tachycardia, the plasma iANP increased gradually and did not reach significantly elevated levels until 10 min into the stimulation period. After 20 min of tachycardia iANP was almost 200 pg/ml. Immunoreactive ANP was measured prior to and following extraction. Although the basal levels of iANP were higher in the unextracted than in extracted plasma (62 vs. 22 pg/ml), the time course of changes in iANP was identical in both. The gradual increase in iANP suggests that the release of iANP in this model may not simply be a consequence of the increase in atrial pressure.

Animals↗
PubMed1986

Relation of Still's murmur, small aortic diameter and high aortic velocity.

The origin of Still's innocent murmur, first described in 1909, is obscure. Seventy normal children and young adults, 29 with Still's murmur and 41 with no murmur, were studied. Pulsed Doppler and 2-dimensional echocardiography were used to evaluate possible causes, including tricuspid regurgitation, left ventricular bands, ascending and descending aortic and pulmonary velocities, ascending aortic diameter, and magnitude of spectral widths. Mean ascending aortic diameter relative to body surface area was significantly smaller for the group with Still's murmur (p less than 0.001). Since cardiac output was similar for the 2 groups, the average peak ascending velocity (133 cm/s) and average peak descending aortic velocity (118 cm/s) were significantly higher in the innocent murmur group as compared to similar respective means in the control group without the murmur (107 and 104 cm/s, respectively) (p less than 0.001 and p less than 0.01, respectively). No significant differences were found when the 2 groups were compared with respect to mean peak pulmonary artery velocity adjusted for body size, spectral widths in the ascending and descending aorta and in the pulmonary artery, and the presence of tricuspid regurgitation or ventricular bands. These observations suggest that the origin of Still's murmur is related to a small ascending aortic diameter with concomitant high aortic blood flow velocity.

Adolescent↗
PubMed1986

Tachycardia releases atrial natriuretic peptide in the anesthetized rabbit.

In anesthetized, vagotomized rabbits the plasma concentration of immunoreactive atrial natriuretic peptide (IR-ANP) was found to be 58.5 +/- 3.4 pg/mL (n = 18) when measured using a radio-immunoassay. Tachycardia, induced by electrical pacing of the right atrium, resulted in increased plasma levels of IR-ANP. The size of the increase in IR-ANP appeared to be related to the degree of tachycardia induced. The release of IR-ANP with tachycardia was unaffected by beta-adrenergic blockade with atenolol (2 mg/kg), muscarinic blockade with atropine (2 mg/kg) or ganglionic blockade with hexamethonium (10 mg/kg). The results show that IR-ANP is released in response to tachycardia and that this does not involve a neuronal reflex.

Acetylcholine↗
PubMed1986

Haemodynamic and plasma vasopressin responses during high-dose fentanyl or sufentanil anaesthesia.

This study compared the haemodynamic and arginine vasopressin responses of patients to fentanyl or sufentanil anaesthesia for coronary artery bypass surgery. Fourteen normotensive patients with normal left ventricular function were studied. Patients were induced with fentanyl (N = 7) 37.5 micrograms X kg-1 or sufentanil (N = 7) 7.5 micrograms X kg-1 by intravenous infusion over three minutes. Clinically important chest wall rigidity, bradycardia and recall of intraoperative events did not occur. All of the fentanyl patients became hypertensive after induction and five required vasodilator therapy since they did not respond to boluses of fentanyl (12.5 micrograms X kg-1). Two of these five patients had S-T depression greater than 1 mm. Five patients in the sufentanil group became hypertensive after induction. Four of these patients responded to additional sufentanil (3.75 micrograms X kg-1) while one required vasodilator therapy for concomitant S-T depression. Sufentanil attenuated the increase of arginine vasopressin during cardiopulmonary bypass. Levels of arginine vasopressin in the fentanyl group were significantly higher than those of the sufentanil group during bypass. Levels of AVP after bypass were higher in the sufentanil group. The incidence of hypertension was similar in both groups. The hypertension was more easily treated with sufentanil but concomitant vasodilators (nitroglycerine) were required in both patient groups. Neither fentanyl in doses up to 128 +/- 8.7 micrograms X kg-1 nor sufentanil in doses up to 23 +/- 1.4 micrograms X kg-1 can be used as sole agents for anaesthesia in adult coronary artery bypass patients with good ventricular function when induction times are three minutes and bolus top-up doses are used.

Adult↗
PubMed1986

Heterologous radioimmunoassay of atrial natriuretic polypeptide in dog and rabbit plasma.

Atrial natriuretic peptide (ANP) was measured in plasma of dogs and rabbits by radioimmunoassay (RIA) using a commercially available anti alpha-ANP serum and compared to our measurements of ANP in rats and humans. Plasma concentration of ANP in dog coronary sinus (234.9 +/- 41.0 pg/ml) was significantly greater than in systemic arterial blood (81.2 +/- 8.4 pg/ml). Gel filtration of dog coronary sinus plasma resulted in an ANP peak with the elution volume (Ve) of synthetic atriopeptin III (AIII) and a minor peak eluting with the void volume (Vo). Rabbit systemic arterial plasma ANP was 53.3 +/- 4.3 pg/ml and yielded one peak, with a Ve of AIII. Ion exchange chromatography of dog and rabbit atrial extracts (AE) resulted in a major ANP region which resembled AIII. Gel filtration of AE showed larger molecular species as well as AIII. Dilutions of dog and rabbit plasma and AE were parallel with the AIII standard in radioimmunoassay.

Animals↗
PubMed1986

Abnormalities of the mitral valve in congenitally corrected transposition (discordant atrioventricular and ventriculoarterial connections).

Abnormalities of the mitral valve were found in 16 (55%) of 29 necropsy specimens of hearts with congenitally corrected transposition of the great arteries (discordant atrioventricular and ventriculoarterial connections). These abnormalities were most commonly of cusp number (21%) and tension apparatus (21%). Dysplasia of the valve was less common (10%), and other abnormalities identified included common valve, stenosis, and cleft valve. Some of the cases showed more than one morphological abnormality. The median age at death in those cases with mitral valve abnormalities was significantly higher than those without. More females than males had valves affected (ratio 2:1). Malformations such as ventricular septal defect and tricuspid or pulmonary valve anomalies were represented in similar proportions in cases with and without mitral anomalies.

Abnormalities, Multiple↗
PubMed1986

Plasma vasopressin response to haemorrhage in the anaesthetized rabbit.

In chloralose-urethane anaesthetized rabbits the acute circulatory and plasma vasopressin (pAVP) responses to moderate haemorrhage of 6 mL/kg body weight (10% blood volume) were followed after serial section of the aortic, vagus, and carotid sinus nerves. With all nerves intact, haemorrhage resulted in significant increases in pAVP, accompanied by decreases in systemic arterial pressure and right atrial pressure. With subsequent section of each afferent nerve, pAVP still increased in response to haemorrhage regardless of the order of nerve section. These results suggest that, in the anaesthetized rabbit, there is a further component of the pAVP response to haemorrhage, in addition to those carried in the aortic, vagus, and carotid sinus nerves.

Animals↗
PubMed1986

Time course of release of atrial natriuretic peptide in the anaesthetized dog.

In 12 chloralose anaesthetized dogs plasma concentration of immunoreactive atrial natriuretic peptide (IR-ANP) was measured using a radioimmunoassay. Plasma IR-ANP was 74 +/- 4.8 pg/mL (mean +/- SE) and increased by 39 +/- 4.1 pg/mL when left atrial pressure was increased by 10 cm H2O during partial mitral obstruction. Observation of the time course of the changes in IR-ANP during atrial distension showed that IR-ANP was increased within 2 min of atrial distension and declined after atrial distension, with a half-time of 4.5 min. The time course of the changes in IR-ANP was unaffected by vagotomy or administration of atenolol. Maximum electrical stimulation of the right ansa subclavia failed to produce any change in IR-ANP. IR-ANP was higher in coronary sinus plasma than in femoral arterial plasma confirming that the heart was the source of the IR-ANP. The results support the hypothesis that IR-ANP is released from the heart by a direct effect of stretch of the atrial wall rather than by a neural or humoral mechanism involving a reflex from atrial receptors.

Animals↗
PubMed1986

The role of 99mTc HIDA cholescintigraphy in the diagnosis of acute gallbladder disease: comparison with oral cholecystography and ultrasonography.

Fifty-four patients with suspected acute cholecystitis underwent 99mTc HIDA cholescintigraphy, ultrasonography and oral cholecystography. The correct diagnosis was reached in 49 patients by cholescintigraphy (91%) in 35 (65%) by ultrasonography and in 45 (83%) by oral cholecystography. 99mTc HIDA cholescintigraphy provides a rapid accurate diagnosis with minimal discomfort to the patient and is the investigation of choice for patients with symptoms of acute gallbladder disease, particularly if early cholecystectomy is to be considered.

Acute Disease↗
PubMed1986

Intussusception.

Explore the source record for details and available documents.

Child↗
PubMed1985

Inflammatory response induced by intrapleural injection of antiserum to IgE in rat. An evaluation of the role of histamine.

Intrapleural injection of antiserum to rat IgE (anti-IgE) into rats resulted in release of histamine from mast cells and rapid effusion of fluid and plasma proteins into the pleural cavity. By 4 hr this was followed by infiltration of neutrophils. These responses were dependent on the amount of anti-IgE injected, and maximal responses were greater than those obtained with compound 48/80. The effusion of fluid and protein, but not the infiltration of cells, was partially suppressed by prior treatment with the H1 histamine receptor antagonist mepyramine (5 mg/kg, s.c.) or the H2 antagonist metiamide (100 mg/kg, s.c.) and was almost totally suppressed (85-88%) when both drugs were administered simultaneously. Neither methysergide (1 and 4 mg/kg, s.c.) nor indomethacin (5 and 10 mg/kg, i.v.) had an effect on the responses to anti-IgE. Although it seemed likely that histamine was a primary mediator of increased vascular permeability, the intrapleural injection of histamine agonists or histamine in large amounts (50 micrograms) provoked a much less intense response than did anti-IgE. The effects of injected histamine may not, therefore, mimic those induced by histamine released from mast cells in situ. The intrapleural injection of histamine releasers such as anti-IgE may serve as a useful model to test the therapeutic efficacy of antihistamine drugs. The present results also confirm previous reports that localized neutrophil infiltration occurs after mast cell degranulation.

Animals↗
PubMed1985

A comparison of information obtained by ultrasound examination and cardiac catheterisation in paediatric patients with congenital heart disease.

Fifty-eight paediatric patients were studied by cross-sectional echocardiography and pulsed Doppler ultrasound in a blind fashion. The information obtained was compared with data collected at cardiac catheterisation. The correct anatomical diagnosis was made by ultrasound in almost all cases but in 11 patients the diagnosis was incomplete or incorrect. Flow measurements made at the tricuspid valve, the pulmonary trunk and the ascending aorta using pulsed Doppler ultrasound correlated well with Fick measurements (r greater than 0.9 at all three sites). The correlation of pressure gradients by the two methods was 0.94. Measurement of the time to peak velocity in the pulmonary trunk provided a method for the identification of patients with elevated pulmonary pressure but the relationship with measured pressures was not sufficiently strong to provide a high degree of reliability.

Blood Flow Velocity↗
PubMed1985

Diastolic forward blood flow in the pulmonary artery detected by Doppler echocardiography.

The etiology of diastolic motion of the pulmonary valve seen on the M-mode echocardiogram has been the subject of much debate. To further investigate diastolic events in the pulmonary artery, the patterns of diastolic pulmonary artery blood flow velocity were studied using pulsed Doppler echocardiography in patients with a normal heart. Two diastolic waveforms were found, one in early diastole related to passive filling of the right ventricle and one in late diastole related to atrial contraction. These waveforms were also related to the two recognized phases of diastolic pulmonary valve motion detected by M-mode echocardiography. The presence of biphasic diastolic blood flow in the pulmonary artery was confirmed by electromagnetic flow velocimetry in four additional patients with various cardiac diseases and normal right heart pressures. It is concluded that both atrial contraction and passive right ventricular filling produce blood flow in the pulmonary artery.

Adolescent↗
PubMed1985

Normal intracardiac and great artery blood velocity measurements by pulsed Doppler echocardiography.

One hundred and 10 normal subjects were studied by pulsed Doppler velocimetry to determine the range of values of blood velocity across the cardiac valves and in the great vessels. Modal peak velocities of 1.55 m/s occurred in the left heart, but right heart peak velocities were lower. In most sites a statistically significant inverse relation between peak velocities and age or body surface area was found. Time to peak velcocity in the pulmonary artery and ascending aorta increased significantly with age and was shorter in the aorta than in the pulmonary artery. These data were developed to serve as standards for the assessment of values recorded in patients with congenital and acquired cardiac disease.

Adolescent↗
PubMed1985

Increased blood velocities in the heart and great vessels of patients with congenital heart disease. An assessment of their significance in the absence of valvar stenosis.

During a previous investigation and during routine clinical Doppler echocardiography velocities distal to normal valves were found to be increased in patients with congenital heart disease. To investigate this observation the velocity proximal and distal to cardiac valves was recorded in 56 patients with congenital heart disease. No detectable pressure gradient had been found across these valves at catheterisation and no velocity gradient greater than 20 cm/s was found across them by range gated Doppler echocardiography. In 82% of the patients, however, the blood velocity across one or more valves exceeded normal limits. Increased velocities were found at the tricuspid inflow (55%), pulmonary artery (38%), mitral inflow (34%), and ascending aorta (11%). Factors predisposing to the presence of increased velocities in these areas were increased flow through the valve and decreased compliance of the receiving chamber. This study shows the necessity for recording velocity both proximal and distal to a valve before a gradient is calculated according to the modified Bernouilli equation.

Adolescent↗