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Biomedical subjects

N Aspin

Publications and source records attributed to N Aspin.

13 recordsLinked to original sources
PubMed1979

Cilia with defective radial spokes: a cause of human respiratory disease.

We studied the fine structure of respiratory-tract cilia in three siblings with chronic respiratory disease, comparing them with those from a patient with Kartagener's syndrome who had dynein-deficient cilia and with control patients who had chronic bronchitis or chronic sinusitis. Electron microscopy of the siblings revealed a new abnormality in the ciliary axoneme--namely, lack of the radial spokes. Their cilia showed an eccentric central pair of tubules but otherwise had a normal central sheath, outer-doublet microtubules, nexin links and dynein arms. The cilia were immotile. Mucociliary clearance was completely lacking in the three siblings and in the patient with Kartagener's syndrome, but was normal in their parents and unaffected siblings. Sperm from the male sibling showed identical structural abnormalities and were immotile. We consider the radial spoke defect to be the congenital anomaly responsible for dysfunction of the mucociliary clearance mechanism in these three patients and of the immotile sperm in one of the them. This defect is apparently another cause of the "immotilecilia syndrome."

Adult↗
PubMed1978

A mathematical description of the airways of the human lungs.

To study the physiological implications of the morphological structure of the conducting airways of the human lungs algorithms are derived for Model I of Horsfield et al. (1971). These algorithms produce descriptions of every pathway from the trachea to the respiratory bronchioles in terms of the combined airway orders. The distributions of surface area and circumference with airway order for this model are given. Also illustrated is the frequency distribution of pathway lengths in the lungs. Computations involving fluid flow in the airways are illustrated by developing a model for mucociliary clearance.

Computers↗
PubMed1978

Effect of body position on carbon monoxide diffusing capacity in asymptomatic smokers and nonsmokers.

We measured carbon monoxide diffusion capacity (DLCO) in the sitting and supine position in 73 apparently normal subjects (41 nonsmokers and 32 smokers). The coefficient of DLCO standardized for alveolar volume (KCO) was less in the smokers than in the nonsmokers (P less than 0.05) in the sitting position, but the separation was wider in the supine posture (P less than 0.01). The per cent changes between supine and sitting KCO (deltaKCO) were shown to be age dependent in both nonsmokers and smokers, but this age dependence was more accentuated in the latter group. Only 3 smokers were below the 95 per cent confidence limit of nonsmokers for KCO in the sitting position, but there were 7 smokers below that limit for deltaKCO. An attempt was made, using intravenous injection of xenon-133, to study the mechanism of this impairment. Persons who failed to increase KCO in the supine posture showed an ability to increase apical blood flow in that position. The mechanisms of impairment in deltaKCO remain to be explained and may be due either to a predominant apical defect or to a widespread abnormality of the pulmonary capillary bed.

Adult↗
PubMed1977

The incidence of radiation pneumonitis as a result of single fraction upper half body irradiation.

The incidence of radiation pneumonitis was determined in 43 patients following a single fraction half body (UHB) irradiation. Radiographs taken before and at least 4 months after UHB treatment were scored for evidence of pneumonitis. Nine patients received only pulmonary irradiation from the UHB treatment. There was no evidence of radiation pneumonitis in eight for whom there was adequate follow up. From this and other supportive evidence presented in this retrospective study, it is suggested that a total lung irradiation of 800 rads produces no changes that can be seen radiographically, provided there has been no previous major pulmonary irradiation or concurrent malignant pulmonary disease. In patients who received additional mediastinal irradiation, severe changes appeared within this field while mild to moderate radiographic changes were seen outside the mediastinal field.

Breast Neoplasms↗
PubMed1977

Physiological and radiographic assessment during the development of pulmonary radiation fibrosis.

Repeated regional measurements of pulmonary blood flow and ventilation were performed in 25 patients irradiated for breast cancer. Patients were studied before and at varying times after (16 to 47 days) the start of radiotherapy. At the same time, chest radiographs were taken and symptoms recorded. Of all the parameters measured, blood flow showed the earliest and greatest decrease. Since changed in blood flow at 60 days are predictive of the changes at 300 days, we believe that earlier studies during the course of irradiation could be useful in predicting long-term effects.

Breast Neoplasms↗
PubMed1977

Effects of gravity on tracheal mucus transport rates in normal subjects and in patients with cystic fibrosis.

A noninvasive, radionuclide imaging technique for measuring the rate of mucus clearance in the trachea (RT), was used to study gravitational effects on mucus clearance in 13 patients with cystic fibrosis (CF), average age 17 years; 7 normal, nonsmoking adults, average age 26 years; and a normal subject who was recovering from an acute upper respiratory tract infection (URTI). In the upright position, nine of the CF patients and the subject with URTI demonstrated abnormal tracheal mucus clearance which approached normal when they were placed in 25 degrees headdown position. The normal subjects and two of the CF patients showed no significant difference in the RT measured in the two positions. The results of the study indicate that the force of gravity can be a major influence on tracheal mucus clearance in CF and URTI subjects. This conclusion supports the use of postural drainage as an effective form of therapy in patients with cystic fibrosis.

Adolescent↗
PubMed1976

Mucociliary transport in trachea of patients with cystic fibrosis.

Mucociliary tracheal transport rates were measured in 20 patients with cystic fibrosis, in whom these rates ranged from 0 to 12.8 mm/min. The patients were divided into 3 roughly equal groups on the basis of their transport rates. (1) Those in whom no abnormality in mucociliary transport was detected in the trachea; (2) those in whom normal transport rates were measured but in whom abnormalities such as cessation, or reversal of bolus movement were observed; (3) those in whom no normal transport rates were observed. In the first group the rates were similar to those observed in a population of healthy adults. These normal rates were observed in some patients who had a productive cough. The mean mucociliary tracheal transport rate increased with increasing maximum midexpiratory flow. Those patients with a low Shwachman score and poor arterial oxygen tension tended to fall into groups 2 and 3. In the ciliary dyskinesia assay in rabbit trachea the serum from the patients with the higher transport rates tended to initiate more rapid discharge of material from the epithelium and ciliary dyskinesia.

Adolescent↗
PubMed1976

Long-distance transmission of digital scintillation camera signals.

A system is described for the long-distance transmission of digital positional information from a scintillation camera to a computer through a shielded multiple-twisted-pair cable. Data errors caused by noise induction along the cable are completely eliminated. The operation of the complete interface and its routine testing are described.

Diagnosis, Computer-Assisted↗
PubMed1975

Mucociliary tracheal transport rates in man.

A new method for measuring mucociliary tracheal transport rates (MTTR's) is described. An aqueous aerosol containing albumin microspheres labeled with 99mTc was inhaled in such a manner that it was deposited in local concentrations in the large airways. These boli of microspheres were transported up the trachea and their MTTR's measured using a gamma camera. MTTR's were measured in 42 healthy nonsmoking adults (32 men and 10 women, mean age 28 yr). The mean MTTR's appeared to be log normally distributed with a geometric mean of 3.6 mm/min and a coefficient of variation of 75%. The MTTR's of men and women were similar. Each individual's short-term coefficient of variation was 25%. Twenty-two repeat studies 1 wk to 15 mo apart showed the variation within individuals was less than between individuals. The parasympatholytic drug, atropine (0.6 mg iv) decreased MTTR's for at least 3 h. Inhalation of the sympathomimetic drug, Th1165a increased MTTR's. Chronic and acute smoking did not appreciably change the MTTR'S.

Adrenergic beta-Agonists↗
PubMedDate not supplied

A comparison of three radionuclide techniques for measuring blood flow to rat extremities.

A detailed comparison of three radionuclide techniques to estimate blood flow was done in the rat hind limb under reduced, normal and increased blood flow. The techniques compared were the washout of intra-arterial and intra-muscular Xenon-133 and the accumulation of radioactive microspheres in the reference organ technique. There was no significant difference between the three techniques at each of the three flow states. This confirmed that the simpler I.M. Xenon technique is a useful and accurate technique in estimating low blood flow rates in small animals. It was found that the skin puncture had to be sealed after the intra-muscular injection of Xenon to obtain valid results.

Animals↗
PubMedDate not supplied

Regional and total lung function in patients following pulmonary irradiation.

Regional and total lung function measurements and chest radiographs were obtained from 18 patients with cancer of the breast from 3 months to 6.7 years after the start of treatment. A control group of 20 patients was studied before radiotherapy but after mastectomy. The functional parameter most affected by radiation was blood flow. In some cases in which the radiographic changes were mild the functional measurements indicated severe vascular damage. The radiation appears to reduce the number and efficiency of functioning lung units within the irradiated region.

Adult↗