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Biomedical subjects

R Heaton

Publications and source records attributed to R Heaton.

30 records · Page 2Linked to original sources
PubMed1988

Ventilatory and circulatory responses at the onset of exercise in man following heart or heart-lung transplantation.

1. Ventilatory and cardiovascular responses to the onset of voluntary and electrically induced leg exercise were studied in six patients following heart transplantation and five following heart-lung transplantation; the results were compared between the patient groups and also with responses from a group of normal subjects. 2. Oxygen consumption, carbon dioxide production and ventilation and its components were measured over two 30 s periods prior to, and two 30 s periods following, the onset of exercise. Relative changes in stroke volume and cardiac output were derived from ensemble-averaged Doppler measurements of ascending aortic blood velocity over the same 30 s periods. 3. None of the groups of subjects showed any significant differences in responses to voluntary exercise compared to electrically induced exercise of similar work pattern and intensity. 4. Compared to normal controls, the transplanted subjects showed higher resting heart rates which did not increase at the onset of exercise; stroke volume increased, but less than in the normal subjects. The resulting cardiac output increases in the transplanted subjects were minimal compared to the normal subjects. 5. Ventilation and oxygen uptake increased immediately and with similar magnitude in all three groups. 6. These results show that in the same individual it is possible to have an appropriate ventilatory response to the onset of exercise in the presumed absence of a normal corticospinal input to the exercising muscles (electrically induced exercise) and afferent neural information from the lungs and heart, and in the absence of a normal circulatory response to exercise. The mechanisms underlying this ventilatory response remain undetermined.

Adult↗
PubMed1988

Bronchial reactivity to methacholine after combined heart-lung transplantation.

The operation of combined heart-lung transplantation results in acute denervation of the heart, lungs, and airways below the level of the trachea. The bronchoconstrictor response to inhaled methacholine of 12 recipients of heart-lung transplants was compared with that of 12 recipients of heart transplants having similar medication and 12 normal subjects. The median dose of methacholine that produced a reduction of at least 20% in the FEV1 (PC20) for the recipients of heart-lung transplants (8 mg/ml) was significantly lower than that for the recipients of heart transplants (64 mg/ml) and normal subjects (greater than 64 mg/ml). The increased airway reactivity may be related to the effects of chronic pulmonary denervation or subclinical inflammation in the airways. The effect of denervation on the response to full inspiration during bronchoconstriction was studied in six patients with heart-lung transplants by means of partial and maximal forced expiratory manoeuvres. Four showed bronchodilation after a deep breath, indicating that this response can occur after extrinsic pulmonary denervation in man. The patients with heart-lung transplants described a "tight" sensation in the anterior chest during bronchoconstriction, indicating that this sensation is not dependent on pulmonary innervation.

Adolescent↗
PubMed1988

Clinical features and therapy of acute thallium poisoning.

Severe acute thallium poisoning in a young man is described. He presented with transient loss of consciousness and paraesthesiae of finger tips and lips, with a blood thallium concentration of 5750 micrograms/l (levels above 200 micrograms/l are toxic). He rapidly lost limb sensation and power and later required temporary mechanical ventilation and nasogastric feeding. The neurological sequelae one year afterwards are a flaccid paraparesis, cerebellar ataxia and mental impairment. Immediate cardiovascular complications included hypertension, sinus tachycardia, ECG abnormalities and an episode of ventricular fibrillation. We were able to assess the relative merits of different methods advocated for enhancing thallium excretion. Oral Prussian blue, forced diuresis and haemodialysis were found to be the most effective: 2000 mg of thallium were eliminated over 20 days, 820 mg over 46 days and 225 mg over 25 days respectively by these methods. Haemofiltration was ineffective. Diethyldithiocarbamate, a chelating agent, brought about a rise in serum thallium concentration accompanied by clinical deterioration and its use should be abandoned.

Acute Disease↗
PubMed1988

The elastase: anti-elastase profile in lung lavage from sarcoidosis patients.

One feature of pulmonary sarcoidosis is an increase of lymphocyte numbers in bronchoalveolar lavage fluid (BALF). In some patients the number of polymorphonuclear neutrophils (PMN) also rises. It has been suggested that the prognosis for the latter subjects is likely to be worse than that for the former, but the damaging agent (or agents) released by the PMN have not yet been identified. Therefore, in the current study, the activity of one neutrophilic enzyme, elastase, which is known to damage the pulmonary interstitium, has been assessed in sarcoid BALF and compared to BALF from subjects matched for age, sex and smoking status. As BALF also contains locally-produced and serum-derived inhibitors of elastase, levels of which may change in subjects with sarcoidosis, the serine protease inhibitory capacity and the levels of three anti-elastases have been measured in the samples. Levels of the serum-derived antiproteases, alpha 1 proteinase inhibitor (alpha 1PI) and alpha 2 macroglobulin (alpha 2M) were found to be significantly increased. However, alpha 1PI/albumin and alpha 2M/albumin ratios were unchanged, suggesting that the increased levels were due to an increased permeability of the alveolar-capillary barrier. The total protease inhibitory capacity was elevated and this could be entirely explained by the raised levels of alpha 1PI and alpha 2M. Levels of the locally-produced inhibitor were unaltered. The elastolytic capacity of sarcoid BALF was unchanged. Thus, the elastase: anti-elastase balance was shifted against elastolytic activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Controlled trial of respiratory health worker visiting patients with chronic respiratory disability.

Seventy five patients with chronic respiratory disability were randomised to a group visited by a respiratory health worker (42) or control group (33). The first group was visited monthly by a respiratory nurse, who gave education and support. The effect of the intervention was assessed in terms of quality of life (by questionnaires), the number and duration of admissions to hospital, and the number of deaths. The questionnaires on quality of life showed no changes in either group during the study, but nearly all of the group visited by a respiratory health worker said that they valued the visits and wished them to continue. Their knowledge about their condition also improved compared with that of the controls. The duration of stay in hospital for respiratory reasons in the group visited by a respiratory health worker was longer than that of control patients. This was explained by their being scored as more ill than the controls on admission. Fewer patients died in the group visited by a respiratory health worker than in the control group (p = 0.11). The patients in the group visited by respiratory health workers may have survived longer because they sought help rather than dying at home. If confirmed this could have implications for the cost of their care.

Aged↗
PubMed1985

Effects of ketotifen on in vitro bronchoconstriction.

We have studied the effects of Ketotifen [Ke] (10(-4)M and 10(-6)M) on two in vitro models of bronchoconstriction: actively sensitized guinea-pig trachea (GPT), and passively sensitized human bronchial muscle (HBM). Experiments were performed on matched pairs of tissues. Cumulative dose response curves [CDRC] for histamine and acetyl choline were constructed, and repeated after pre-incubation with Ke or saline control. The effect of Ke on maximal antigen induced contractions was also studied. Contraction of GPT by histamine and acetyl choline was inhibited by Ke 10(-4)M, though this effect was not apparent at high doses of acetyl choline. Ke 10(-6)M had a weaker inhibitory effect on histamine and acetyl choline induced responses. Contraction of GPT by antigen was unaffected by Ketotifen. In the HBM model, Ke 10(-4)M inhibited acetyl choline and antigen induced responses. Ketotifen, 10(-6)M had an inhibitory effect on acetyl choline induced contractions, though this was small, and not seen at higher agonist doses. Contraction of HBM by antigen was unaffected by Ke 10(-6)M. We were unable to obtain reproducible CD RC's to histamine with HBM. The weaker or absent effects of Ke 10(-6)M, a level close to that obtained in clinical practice, may explain some of the poor results of clinical trials, and suggest that efficacy may be improved by the use of higher doses.

Acetylcholine↗
PubMedDate not supplied

Psychiatric disorders in patients with fibromyalgia. A multicenter investigation.

The authors conducted an investigation in four tertiary-care centers to determine if psychiatric comorbidity and psychological variables were predictive of functional impairment in patients with fibromyalgia syndrome (FMS). Seventy-three individuals were administered the Structured Clinical Interview for DSM-III-R, the Rand 36-item Health Survey (SF-36), and multiple self-report measures. The patients with FMS were found to have a high lifetime and current prevalence of major depression and panic disorder. The most common disorders were major depression (lifetime [L] = 68%, current [C] = 22%); dysthymia (10% [C only]); panic disorder (L = 16%, C = 7%); and simple phobia (L = 16%, C = 12%). The self-report scales revealed significant elevations in depression, anxiety, neuroticism, and hypochondriasis. Functional impairment on all measures of the SF-36 was severe (e.g., physical functioning = 45.5 and role limitations due to physical problems = 20.0). Stepwise multiple-regression analysis revealed that current anxiety was the only variable that predicted a significant proportion of the variance (29%) in SF-36 physical functioning. Thus, in this multicenter study, the persons with FMS exhibited marked functional impairment, high levels of some lifetime and current psychiatric disorders, and significant current psychological distress. Current anxiety level appears to be an important correlate of functional impairment in individuals with FMS.

Adult↗