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Biomedical subjects

R H Edwards

Publications and source records attributed to R H Edwards.

At least 217 records · Page 12Linked to original sources
PubMed1989

Quantitative magnetic resonance imaging in autologous bone marrow transplantation for Hodgkin's disease.

Fifteen consecutive patients with refractory or relapsed Hodgkin's disease (HD) referred for autologous bone marrow transplantation (ABMT) underwent quantitative magnetic resonance (MR) studies of the lumbar vertebral bone marrow. Markedly elevated lumbar vertebral marrow T1 values suggestive of bone marrow involvement with HD were seen in four patients, two of whom had no evidence of HD on bilateral iliac crest bone marrow biopsy. Serial studies showed normalisation of T1 values in the post-transplant period. T1 relaxation rate correlated positively with time to engraftment following ABMT and a significant correlation (r = 0.73, 0.02 greater than P greater than 0.01) between T2 relaxation rate and granulocyte and macrophage colony forming units (CFU-GM) of processed bone marrow was seen. This preliminary study illustrates the potential role of quantitative MRI both in the pre-transplant assessment of patients considered for ABMT and in the post-transplant evaluation of tumour response when marrow involvement with HD is present.

Adult↗
PubMed1989

Management of muscular dystrophy in adults.

Muscular dystrophies in adults present a spectrum of disabilities and medical problems which require diagnosis and timely management. Weight control and orthotic assistance can help the sufferer maintain as near a normal life style as possible. Surgery may offer benefits in selected patients. Major issues such as employment, personal/sexual relations, parenthood, chronic disability and handicap, require clear analysis and sympathetic management. Later, respiratory and/or cardiac failure become significant considerations. Currently the move is towards a policy of respiratory support but it is not yet clear how much this may improve the quality or length of life.

Adult↗
PubMed1989

Isoforms of creatine kinase: MM in the study of skeletal muscle damage.

Isoforms of creatine kinase (CK) MM have been analysed in plasma from normal subjects and patients with muscular dystrophy using isoelectric focusing techniques. Most plasma samples analysed contained three isoforms of CK-MM of isoelectric points 7.26 (MMI), 6.85 (MMII) and 6.45 (MMIII) although in some plasma samples two additional isoforms of isoelectric points 7.12 and 6.65 were seen. Patients with muscular dystrophy were found to have a generally higher proportion of CK-MMI in their plasma than normal subjects and this was relatively unaffected by large variations in the total creatine kinase activity. By comparison eccentric exercise in normal subjects was found to result in a large increase in total plasma CK activity which then declined to normal over a period of approximately 6 days. CK-MMI was found to increase initially followed by CK-MMII and CK-MMIII. Analysis of the isoforms in biopsy samples of human muscle revealed the presence of two of the bands found in plasma (CK-MMI and MMII) and a third muscle specific isoform, while incubation of muscle homogenates in plasma induced the formation of CK-MMIII and the two isoforms of pI 7.12 and 6.65. It is concluded that analyses of CK-MM isoforms in human plasma can provide useful information on the extent and relative time course following an episode of muscle damage but that in patients with muscular dystrophy the large variations in plasma CK activity are not reflected in the proportion of CK found in each isoform.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Protriptyline treatment of sleep hypoxaemia in Duchenne muscular dystrophy.

Protriptyline 20 mg daily reduced the total time spent in rapid eye movement sleep in an open study in four subjects with Duchenne muscular dystrophy. Sleep related hypoxaemia and episodes of desaturation were reduced. Anticholinergic side effects were prominent, however, in these patients, precluding its use for regular treatment.

Adolescent↗
PubMed1989

Oxygen treatment of sleep hypoxaemia in Duchenne muscular dystrophy.

Patients with Duchenne muscular dystrophy develop progressive ventilatory muscle weakness and often die of respiratory complications. Recurrent, often profound, hypoxaemia has been shown in a previous study by this group to occur during rapid eye movement (REM) sleep in these patients before they develop sleep symptoms. In this study the efficacy and physiological effects of nocturnal oxygen in such patients have been assessed. Seven patients with Duchenne muscular dystrophy (age range 16-22 years; mean vital capacity 1.37 litres) with normal arterial blood gas tensions when awake were investigated by standard overnight polysomnography on an acclimatization night followed by two successive nights on which they received room air and nasal oxygen (2 litres/min) respectively in random order. Total sleep time, proportion of REM and non-REM sleep, and frequency and duration of arousals were similar on the two nights. When breathing air six of the seven subjects developed oxygen desaturation of more than 5% during REM sleep. With oxygen only one subject showed any oxygen desaturation exceeding 2.5%. Oxygen desaturation was associated with periods of hypopnoea or cessation of respiratory effort. The mean duration of episodes of hypopnoea and apnoea was prolonged during oxygen breathing by 19% and the mean duration of episodes during REM sleep by 33% (the proportion of REM sleep associated with hypopnoea and apnoea increased in all subjects). Heart rate in non-REM sleep fell by 9.3%; heart rate variation in REM and non-REM sleep was unchanged. These acute studies show that oxygen reduces the sleep hypoxaemia associated with respiratory muscle weakness; whether long term treatment will be possible or desirable is not clear as oxygen potentiates the underlying ventilatory disturbance.

Adolescent↗
PubMed1989

Tuberculous retropharyngeal abscess producing respiratory obstruction.

Oropharyngeal tuberculosis is a rare presentation of the disease even in the presence of extensive pulmonary tuberculosis. A case is described in which a retropharyngeal abscess, causing stridor and threatening respiratory obstruction, was the only manifestation of Mycobacterium tuberculosis infection.

Abscess↗
PubMed1989

Bone marrow disorders: characterization with quantitative MR imaging.

Thirty patients with various hematologic disorders and 15 healthy control subjects underwent quantitative magnetic resonance (MR) imaging of the lumbar spine with spin-echo techniques. Images of patients with infiltrative bone marrow disorders showed significantly more prolonged T1 times than those of control subjects (P less than .001). It was not possible to distinguish different diffuse infiltrative bone marrow disorders on the basis of T1 values. Aplastic anemia could be distinguished from normality because of significantly shortened T1 (P less than .001). A significant correlation was seen between T1 and bone marrow cellularity (r = .74, P less than .001). T2 was of no value in the characterization of bone marrow disorders. Quantitative MR imaging dose not improve the diagnostic potential of bone marrow imaging in the detection of diffuse marrow infiltrates.

Adult↗
PubMed1989

Selenium metabolism and supplementation in patients with muscular dystrophy.

We studied selenium metabolism in patients with Duchenne muscular dystrophy and in contrast to previous reports found no significant abnormalities in these patients. Supplementation of muscular dystrophy patients and control subjects with sodium selenite (1 mg selenium/day) induced a variable rise in the activity of the selenium-dependent enzyme glutathione peroxidase in plasma and red cells, but no significant change in muscle glutathione peroxidase activities. There was no effect of selenium supplementation on disease activity in the patients with muscular dystrophy. Thiobarbituric acid-reacting substances (an index of free radical-mediated lipid peroxidation) were elevated in the muscle of patients with Duchenne muscular dystrophy in contrast to patients with other forms of muscular dystrophy and control subjects. This elevation was unaffected by selenium supplementation.

Clinical Trials as Topic↗
PubMed1989

Ventilation and breathing pattern during sleep in Duchenne muscular dystrophy.

Ventilatory data, including timing and partitioning of ventilation, were obtained from six subjects with advanced Duchenne muscular dystrophy, aged 16 to 22 years, during polysomnography on two consecutive nights; the subjects were randomized to breathing air or oxygen. Five of the six patients developed oxygen desaturation exceeding 5 percent during rapid eye movement (REM) sleep while breathing air. Minute ventilation on air (the mean of at least six consecutive minutes) was 6.9 +/- 0.7 (SEM) L min-1 but fell, owing to decreases in both tidal volume and frequency, to 4.9 +/- 0.3 L min-1 (p less than 0.05) in slow wave sleep and to 4.5 +/- 0.6 L min-1 (p less than 0.05) in REM sleep. Similar falls were seen on oxygen. The variability of all ventilatory data was significantly greater in REM than non-REM (NREM) sleep. The mean abdominal contribution to breathing was lower than predicted for wakefulness and all sleep stages, and two subjects showed paradoxical abdominal movement in NREM sleep; a correlation (p less than 0.05) existed between the NREM abdominal (diaphragmatic) contribution and the extent of oxygen desaturation subsequently seen in REM. We conclude that although awake minute ventilation is normal in Duchenne muscular dystrophy, hypoventilation occurs in all sleep stages, and those with diaphragmatic dysfunction are especially vulnerable to oxygen desaturation during REM sleep.

Adolescent↗
PubMed1988

Normal muscle strength and fatigability in patients with effort syndromes.

To examine fatigue mechanisms in an unselected series of patients with excess fatigue ("effort syndromes") their muscle function was compared with that of normal subjects. Voluntary performance was assessed with a cycle ergometer to exhaustion and by maximal isometric contractions of the quadriceps femoris. The mean maximal heart rate in patients during ergometry was 89% of the predicted rate, and quadriceps strength was either normal or was inappropriate for the available muscle, which suggested submaximal effort. Contractile performance was examined in the absence of volition with stimulated contractions of the adductor pollicis. During stimulated fatiguing activity patients were neither weaker nor more fatigable than controls; thus the excess fatigue experienced by the patients was not due to a defect of the contractile apparatus. The increased perception of effort must therefore be due to impairment of central rather than peripheral mechanisms. The optimal approach to treatment of effort syndromes combines physical and psychological techniques.

Adult↗
PubMed1988

Apparent haematuria.

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Diagnosis, Differential↗
PubMed1988

Processing of the native nerve growth factor precursor to form biologically active nerve growth factor.

In the mouse submaxillary gland beta nerve growth factor (beta-NGF) forms a complex with two members of the kallikrein family of serine proteases, termed the alpha- and gamma-subunits of NGF. We demonstrate that the beta-NGF precursor produced in mammalian cells via a recombinant vaccinia virus can be cleaved by stoichiometric quantities of the gamma-subunit to produce beta-NGF. Trypsin in catalytic quantities also produces native beta-NGF. Proper cleavage depends critically on the conformation of the precursor. beta-NGF has at least 10-fold more biological activity than its precursor.

Animals↗
PubMed1988

Calcium ionophore enhances the electron spin resonance signal from isolated skeletal muscle.

Electron spin resonance studies of the free radical signal from isolated skeletal muscle during experimental damage have shown that elevation of muscle intracellular calcium with the calcium ionophore A23187 induced an average 61% increase in the amplitude of the signal of g value 2.0047 compared to paired, untreated control muscles, accompanied by a large efflux of intracellular creatine kinase to the external medium. Inhibitors of the calcium-induced loss of cell viability leading to enzyme efflux, i.e., chlorpromazine, phenidone and nordihydroguaiaretic acid had variable effects on the signal, suggesting that the free radical signal obtained from skeletal muscle by electron spin resonance techniques is stimulated by intracellular calcium overload, but is not directly related to the mechanisms by which calcium overload leads to a loss of cell viability leading to intracellular enzyme efflux.

Animals↗