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Biomedical subjects

C B Clayton

Publications and source records attributed to C B Clayton.

At least 19 recordsLinked to original sources

Chest physiotherapy in cystic fibrosis: a comparative study of autogenic drainage and the active cycle of breathing techniques with postural drainage.

BACKGROUND--Autogenic drainage has been suggested as an alternative method of chest physiotherapy in patients with cystic fibrosis. In this study autogenic drainage was compared with the active cycle of breathing techniques (ACBT) together with postural drainage. METHODS--Eighteen patients with cystic fibrosis took part in a randomised two-day crossover trial. There were two sessions of one method of physiotherapy on each day, either autogenic drainage or ACBT. The study days were one week apart. On each day the patients were monitored for six hours. Mucus movement was quantified by a radioaerosol technique. Airway clearance was studied qualitatively using xenon-133 scintigraphic studies at the start and end of each day. Expectorated sputum was collected during and for one hour after each session of physiotherapy. Pulmonary functions tests were performed before and after each session. Oxygen saturation (SaO2) and heart rate were measured before, during, and after each session. RESULTS--Autogenic drainage cleared mucus from the lungs faster than ACBT over the whole day. Both methods improved ventilation, as assessed by the xenon-133 ventilation studies. No overall differences were found in the pulmonary function test results, but more patients had an improved forced expiratory flow from 25% to 75% with autogenic drainage, while more showed an improved forced vital capacity with ACBT. No differences were found in sputum weight and heart rate, nor in mean SaO2 over the series, but four patients desaturated during ACBT. CONCLUSIONS--Autogenic drainage was found to be as good as ACBT at clearing mucus in patients with cystic fibrosis and is therefore an effective method of home physiotherapy. Patients with cystic fibrosis should be assessed as to which method suits them best.

Adolescent↗

A new method for measuring the blood volume of the rat using 113mIndium as a tracer.

A new method is described for the estimation of blood volume in the rat using 113mIndium chloride. No in vitro labelling step is necessary as the isotope binds specifically to transferrin in vivo. Under anaesthesia, an external jugular vein was cannulated for blood sampling and indium chloride injected directly into a lateral tail vein. Three blood samples of 0.2 ml were taken at short intervals and radioactivity measured under standard conditions. Blood volume was found to be 7.46 +/- 0.14 (mean +/- SEM) ml/100 g body weight. Repeating the study of 5 animals gave similar values for blood volume on the 2 occasions (7.23 +/- 0.26 and 6.95 +/- 0.23 ml/100 g, P > 0.05). The new technique was compared with established methods using 51Cr labelled red blood cells and 125Iodinated albumin. In each animal, the 113mIndium technique produced values approximately 10% higher than those obtained using the sum of plasma and red cell mass, in keeping with the known difference between whole body and large vein haematocrit (Indium, 7.20 +/- 0.19 and Iodine with Chromium, 6.40 +/- 0.34 ml/100 g). Data on blood volume determined using 125Iodine as the tracer on these same animals were identical (Indium, 7.20 +/- 0.19 and iodine, 7.16 +/- 0.34 ml/100 g). The method is simple to perform and appears to be at least as accurate and reproducible as established methods for measuring blood volume.

Animals↗

The effect of immunosuppression on the development of cerebral oedema in an experimental model of intracerebral haemorrhage: whole body and regional irradiation.

The oedema which forms around an intracerebral haemorrhage has a complex aetiology. The immune response may have a role in its formation. There is clinical and experimental evidence that circulating leucocytes and platelets may mediate oedema formation. Global depletion of circulating leucocytes and platelets by whole body irradiation in a rodent model of intracerebral haemorrhage was found to confer protection against both ischaemia and oedema formation. This was not a direct effect of irradiation of the brain. The possible mechanisms for this protection are discussed.

Animals↗

Thallous chloride uptake and DNA profile in parathyroid adenomas.

Thallium isotope scintigraphy is used to localize parathyroid adenomas but the mechanism underlying the technique is poorly understood. While larger adenomas are reliably localized the results are less certain for small tumours. This study explores the relationship between cellular DNA profile and thallium uptake (localization accuracy) in 24 parathyroid adenomas. The DNA profile was assessed using flow cytometry and standard subtraction thallium scintigraphy was performed before surgery. Fifteen of the 24 adenomas demonstrated excessive mitotic activity and 13 of these glands were accurately localized. Of the remaining nine glands, only five were localized accurately (P less than 0.01, chi 2 test including Yates' correction). This difference in thallium uptake could not be accounted for on the basis of gland weight. Thallium localization of parathyroid adenomas is related to mitotic activity. This may explain some of the limitations of this technique.

Adenoma↗

Ventilation perfusion lung scans in the management of suspected pulmonary embolism.

The purpose of the study was twofold: (a) to relate the degree of clinical suspicion of pulmonary embolism (PE) to the findings of isotope ventilation-perfusion (V/Q) scans, and (b) to determine the extent to which the scan results influence patient management. A questionnaire was completed by the requesting clinician before V/Q scanning in 60 consecutive in-patients in whom PE had, with varying degrees of probability, been considered possible. Retrospectively, the case notes were reviewed to determine whether or not the patients were anticoagulated when discharged. Prior to scanning, PE was considered probable or almost certain in 35 (58 per cent) patients and unlikely or very unlikely in 25 (42 per cent) patients. Thirty-seven (62 per cent) scans were confidently reported positive or negative for PE; in the remaining 23 (38 per cent) cases, the scan report was necessarily inconclusive. The clinical assessment was supported by the scan result in 23/25 (92 per cent) patients in whom PE was felt unlikely or very unlikely, but in only 14/35 (40 per cent) in whom this diagnosis was felt probable or almost certain. Twenty (33 per cent) patients were already anticoagulated when scanned; this treatment was initiated in nine (15 per cent) and discontinued in eight (13 per cent) in the light of the scan result. Isotope V/Q scans are not always useful in confidently confirming or excluding the presence of PE. Nevertheless, the scan reports, even when necessarily guarded and somewhat at variance with the clinical assessment of the probability of PE, strongly influence clinicians in their decisions as to whether to anticoagulate their patients.

Angiography↗

A double-radionuclide autoradiographic method using N-isopropyl-iodoamphetamine for sequential measurements of local cerebral blood flow.

A double-radionuclide autoradiographic method has been assessed for sequential determinations of local CBF (LCBF). It is based on two successive intravascular injections of N-isopropyl-p-iodoamphetamine (IMP) labelled with different radionuclides, whose concentrations can later be differentiated in the same tissue section using double-radionuclide autoradiography. Previous studies suggested that the distribution of IMP, up to 30 min after its administration, still represents LCBFs. Our data indicate that, provided the tracer is injected directly into the left ventricle, there is little back diffusion from normal brain to blood under physiological conditions for at least 35 min following the tracer injection and an injection of unlabelled IMP, in a dose larger than that used for blood flow determination, does not displace any labelled IMP previously taken up by the brain, nor does it displace any labelled IMP previously accumulated in the lung that would lead to secondary brain uptake. On the basis of these results, we conclude that sequential autoradiographic determinations of LCBF using IMP labelled with different radionuclides is possible. This is a promising experimental method for the simultaneous investigation of changes in LCBF in several CNS structures.

Amphetamines↗

Static and sequential dynamic scintigraphy of the tibia following fracture.

Eighty patients who had sustained a fracture of the tibial shaft were studied by scintigraphy using technetium-99m labelled methylene diphosphonate (99Tcm MDP) and a gamma camera. Static scintigrams were obtained in the early stages following injury and examined for the presence of 'cold spots' which may indicate loss of blood supply to fracture fragments; these were found in 10 per cent of cases but did not bear any definite relationship to the normal progression of union. Sequential dynamic scintigrams were obtained at intervals up to 20 weeks after fracture to determine whether a pattern of uptake of tracer could be identified which correlated with the subsequent progression of union, but no significant difference was observed between fractures healing promptly (less than 20 weeks) and those in which healing was delayed (greater than 20 weeks).

Adolescent↗

Application of Bayes' theorem to the diagnosis of ankylosing spondylitis from radioisotope bone scans.

The ratio of the uptake of radioactivity in each sacroiliac joint to the uptake in the sacrum has been measured in 57 patients with early ankylosing spondylitis and in 51 control subjects. The distribution of ratios of uptake obtained in each of these two groups shows appreciable overlap, and it is shown that the specification of a 'normal range' in this sort of situation can be misleading in the interpretation of the uptake ratio obtained in a given subject. An alternative approach described here is to use Bayes' theorem, which combines a probability based on the numerical value of the measured ratio with the pretest clinical impression about the likelihood of ankylosing spondylitis to yield a post-test probability of the presence of the disease.

Adolescent↗

Scintigraphy and contrast radiography for epiphora.

During a one-year period 53 patients were referred for the investigation of epiphora. All underwent bilateral dacryoscintigraphy. Following the isotope study the patients had either bilateral or unilateral macrodacryocystography; a total of 66 tear ducts were shown by this procedure. The scintigraphs were more sensitive for obstruction (51/66 systems or 77%) than radiography (33/66 systems or 51%). Normal dacryoscintigraphy was always associated with duct patency on dacryocystography. We have concluded that scintigraphy should always be the first investigation and that, if this is normal, radiography is not necessary. The use of digital subtraction imaging for the lacrimal passages is discussed. It is suggested that this may provide information obtained at present only by combining dacryoscintigraphy with conventional contrast radiography.

Humans↗

Scintigraphic appearance of the tibia in the early stages following fracture.

A scintigraphic study of the human tibia in the early stages following fracture of the shaft was carried out to investigate the condition of the blood supply of the main fracture fragments. Using a gamma camera and 99mTc-MDP, scintigraphs were obtained from less than 24 hours to 21 days after injury. A generalized increase in tracer uptake was found in the tibia in all cases. In some cases very early after injury there was an additional local increase at the fracture site. In 10% of cases "cold spots" were observed, which may indicate an impaired blood supply to bone tissue adjacent to the fracture. Neither the presence of a "cold spot" nor any other scintigraphic feature could be correlated with the progress or time to fracture union.

Adolescent↗

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Blood Flow Velocity↗