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Biomedical subjects

C Edwards

Publications and source records attributed to C Edwards.

At least 253 records · Page 14Linked to original sources
PubMed1985

The effects of cognitive task demand on subjective stress and blood glucose levels in diabetics and non-diabetics.

Blood glucose levels (BGLs) and subjective estimate of stress levels (SESLs) were measured repeatedly in 45 min baseline sessions on three successive days in insulin-dependent diabetic and non-diabetic groups. In the diabetic groups the initial level of BG was twice that of the non-diabetic group and BGLs declined steadily within each session but not across sessions whereas BGLs in the non-diabetic group remained steady both within and across sessions. On two subsequent days half of each group performed a high demand and half a low demand task, BGLs and SESLs being assessed before, during and after the stress period. Stress did not appear to induce significant changes in BGL in any of the groups even though SESL measures indicated that the task appeared stressful to the groups. The implications of these findings for the relationship between stress and increases or decreases in BGL are discussed.

Adult↗
PubMed1985

Is an acetylcholine transport system responsible for nonquantal release of acetylcholine at the rodent myoneural junction?

Experiments were performed to investigate the effects on the spontaneous, nonquantal release of acetylcholine (AcCho) from motor nerve terminals of substances known to inhibit the AcCho transport system present in cholinergic synaptic vesicles. In mouse diaphragms, the hyperpolarization normally produced by d-tubocurarine in the endplate area of muscle fibers that had been treated by an anticholinesterase was partly or completely blocked by 2-(4-phenylpiperidino)cyclohexanol (AH5183, 0.1-1 microM), quinacrine (0.1 microM), and tetraphenylborate (1 microM). Since the sensitivity of the subsynaptic area to AcCho was not changed, the block of the hyperpolarizing action of d-tubocurarine indicated in inhibition of the spontaneous, nonquantal release of AcCho. This was confirmed in experiments on rat diaphragm using direct radioenzymatic measurement of the AcCho released into the incubation medium. The release of AcCho from the innervated diaphragm was decreased by about 50% in the presence of AH5183 (0.01-1 microM) and by 42% in the presence of quinacrine (0.1-1 microM). The AcCho released was presumably neural, since the release of AcCho from 4-day denervated diaphragms was not diminished by either AH5183 or quinacrine. The results indicate that the spontaneous release of AcCho from the motor nerve terminals is highly sensitive to low concentrations of specific inhibitors and is probably mediated by a carrier. It is proposed that spontaneous release is due to the incorporation into the membrane of the nerve terminal during exocytosis of the vesicular transport system responsible for moving AcCho into the vesicle.

Acetylcholine↗
PubMed1985

Relationships between the circadian rhythms of TSH, prolactin and cortisol in surgically treated microprolactinoma patients.

Pharmacological doses of glucocorticoids inhibit TSH release both in vivo and in vitro and since the circadian rhythms of TSH and cortisol show a reciprocal relationship, the hypothesis has been advanced that changes in cortisol levels may be a primary determinant of circadian TSH changes. We have tested this hypothesis by studying the relationship between circadian cortisol and TSH rhythms in subjects before and during blockade with metyrapone. Seven patients were studied during their routine post-operative assessment following selective transethmoidal adenomectomy for microprolactinomas. PRL levels were restored to normal (less than 420 mU/l) in all patients by surgery (pre-op: 930-2752 mU/l, post-op: 33-376 mU/l) and the patients also had normal pituitary function in other respects. Blood was sampled hourly for 24 h before and on the third day of treatment with metyrapone (250 mg, 2 hourly). In order to compare circadian rhythms, hormonal data were subjected to cosinor analysis which involved fitting of the data with a cosine function using the method of least squares. The 6% cross reactivity of the cortisol antibody with 11-deoxycortisol was taken into account during the calculation of results. All subjects showed a normal cortisol rhythm which was strikingly blunted during metyrapone treatment. Group mean (+/- SD) TSH mesors, amplitudes and acrophases for control and metyrapone treated subjects were 1.5 +/- 0.26, 1.29 +/- 0.48; 0.46 +/- 0.26, 0.23 +/- 0.13 and -49 degrees +/- 9.8 degrees; -62 degrees +/- 2.7 degrees respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Bronchopulmonary disease in coeliac patients.

This paper describes the necropsy changes in a patient with coeliac disease and respiratory disease and the pulmonary biopsies from 13 other coeliac patients with physiological evidence of a parenchymal lung disorder. Postmortem examination showed partial fibrous obliteration of small airways and dilatation of larger airways, and the biopsies suggested similar changes in the other patients. We were unable to find any evidence of granulomatous or primary interstitial lung disease.

Aged↗
PubMed1985

Clear cell carcinoma of the lung.

Six tumours of the lung initially classified as clear cell carcinoma, were studied. Examination of further material by light and electron microscopy showed adenocarcinomatous differentiation in three cases and squamous differentiation in two. One case showed the features of a large cell anaplastic carcinoma. The clear appearance of the cytoplasm in paraffin sections was due to accumulations of glycogen that were partially removed during processing. It is concluded that clear cell carcinoma is not a single and separate entity.

Adenocarcinoma↗
PubMed1984

Light microscopic observations on the release of vesicles by isolated chromaffin cells.

Cultured bovine adrenal medullary chromaffin cells were stimulated with the secretogogues Ba2+ or carbamyl choline plus Ca2+. With video-enhanced contrast, differential interference contrast microscopy, small vesicles were found to appear on the cell surface during stimulation. The structures were of lower refractive index than the cytoplasm, and their appearance required several tenths of a second. The vesicles are thought to correspond to omega figures seen with electron microscopy due to exocytosis. Many of the structures disappeared within a few seconds, but some appeared to coalesce into larger structures. The large structures may lead to the vacuoles that have been demonstrated to be present following stimulation. The nature of the cellular elements responsible for the vesicle which appeared on the surface was not found with either differential interference or interference reflection microscopy. The simplest explanation is that the refractive index of the elements is similar to that of the cell, and therefore the elements cannot be seen.

Adrenal Medulla↗
PubMed1984

Tissue-specific and light-regulated expression of a pea nuclear gene encoding the small subunit of ribulose-1,5-bisphosphate carboxylase.

We have examined the expression of a member of the multigene family encoding the small subunit (rbcS) of ribulose-1,5-bisphosphate carboxylase in various tissues of pea. The rbcS gene, pPS-2.4, was characterized by DNA sequence analysis and 5' and 3' end mapping of its mRNA transcript. rbcS polypeptides were shown to be differentially present in various tissues of light- and dark-grown plants. Northern analysis shows that compared with green leaves, the level of rbcS mRNA is reduced to approximately 50% in pericarps, 8% in petals and seeds, and 1-3% in etiolated leaves, stems, and roots. 5' S1 nuclease mapping of total rbcS mRNA was used to quantitate the relative amount of pPS-2.4 gene-specific transcripts in each tissue. pPS-2.4 mRNA accounts for approximately 30-35% of total rbcS transcripts in green leaves, but only 5-10% in pericarps, 15-20% in seeds, and is below detection in petals and etiolated leaves. We conclude that the pPS-2.4 gene is expressed in a tissue-specific, light-regulated fashion and that transcriptional controls of individual rbcS genes vary.

Base Sequence↗
PubMed1984

Carbamazepine 10,11-epoxide in children.

Concentrations of carbamazepine (CBZ) and its 10,11-epoxide metabolite (CBZ-E) were measured in simultaneously collected plasma and mixed saliva samples from 15 children (aged 1-13 years). Saliva concentrations of CBZ and CBZ-E were measured in hourly samples taken from six of these children during dose intervals whilst on different dose or dose-frequency regimens. Saliva and plasma CBZ (r = 0.91; P less than 0.001) and CBZ-E (r = 0.91; P less than 0.001) concentrations were significantly correlated. The mean +/- s.d. steady state CBZ-E/CBZ concentration ratio in the six children was 0.40 +/- 0.21 and was similar at all times within the 12 h dose interval. The mean +/- s.d. percentage fluctuation of the combined CBZ + CBZ-E (103.0 +/-28.9) was significantly less than that of CBZ-E (145.5 +/- 52.8) but not CBZ (109.6 +/- 31.1). If CBZ and CBZ-E have equipotent anticonvulsant activity in man, the contribution of CBZ-E approximates to 30% of total anticonvulsant effect in children taking CBZ alone.

Adolescent↗
PubMed1984

A pharmacokinetic study of the recommended dosing schedules of Theo-Dur and Uniphylline.

Theo-Dur, 300 mg twice daily, and Uniphylline, 600 mg once daily taken with food were compared in an open cross-over study in healthy volunteers. Uniphylline had significantly (P less than 0.001) higher peaks, lower troughs and wider variation in theophylline concentrations than Theo-Dur. Peak plasma concentrations were reached earlier for Theo-Dur but the difference failed to reach statistical significance (0.05 less than P less than 0.1). There was no significant difference between the two drugs in area under the plasma concentration time curve. Therapeutic occupancy lasted significantly longer (P less than 0.05) with Theo-Dur; eight volunteers attained 24 h therapeutic occupancy after administration of Theo-Dur compared to 4 h with Uniphylline.

Adult↗
PubMed1984

The larger bronchi in byssinosis: a morphometric study.

The proportions of gland, muscle and cartilage were measured in the named bronchi of 43 byssinotics, and compared with the proportions in normal subjects and chronic bronchitics. The smoking habits and symptomatology of the byssinotics were also investigated. In the byssinotics the proportions of gland, muscle and cartilage were higher than in the normal, non-smoking subject at all levels in the bronchial tree, and were similar to those in chronic bronchitics. The increase was not confined to the lobar bronchi as the results of a previous investigation had suggested. It is concluded that although exposure to cotton dust is a factor in the pathogenesis of chronic byssinosis, anatomical changes in the bronchi of Lancashire cotton workers are non-specific, and are confounded by other environmental factors. Smoking has a deleterious effect on the natural history of the disease, but no morphological difference between smokers and non-smokers was found.

Adult↗
PubMed1984

The effects of the replacement of K+ by Tl+, Rb+, and NH+4 on the muscle membrane potential.

The resting membrane potential (RMP) of mouse diaphragm muscle was measured in solutions containing several concentrations of K+ (0.4 to 5 mmol/l) or one of the following cations: Tl+ (0.4, 1 or 2 mmol/l), Rb+ (1, 2 or 5 mmol/l), or NH+4 (4, 8 or 16 mmol/l). In terms of controlling the RMP, the ratios of the efficacies were Tl+:K+:Rb+:NH+4 = 2.5:1.0:1.0:0.12. These ratios are similar to those of the selectivities of the voltage dependent K+ channel (delayed rectifier) in frog nerve and muscle, and this similarity suggests that the resting membrane potential may be controlled by this channel.

Ammonia↗
PubMed1984

Astrocytes in primary culture have chemically activated sodium channels.

The effects of two neurotoxins, veratridine and alpha-scorpion toxin II, on the resting potential (RMP) of identified astrocytes in primary cell culture were studied using standard electophysiological techniques. Veratridine caused either a series of transient depolarizations or a single sustained depolarization. alpha-Scorpion toxin (II), which alone had no effect on the RMP, increased the duration of the veratridine-induced transient depolarizations. The depolarization caused by veratridine, or veratridine plus alpha-scorpion toxin II, was reversibly inhibited by tetrodotoxin and was reversibly reduced in magnitude by reductions of the external sodium concentration. Cells that were depolarized by veratridine were shown to contain glial fibrillary acidic protein, a marker considered specific for astrocytes. The effect of long-term (10 sec) hyperpolarizing and depolarizing current pulses on the RMP were also studied using two microelectrodes, i.e., dual impalement. In the absence of veratridine, the RMP returned to its original value after termination of the hyperpolarizing current, and the current-voltage relationship was found to be linear over a wide range of membrane potentials. In the presence of veratridine, termination of the hyperpolarizing current produced a transient depolarization that was sensitive to tetrodotoxin. Depolarizing current pulses were without effect. These results show that astrocytes in primary culture have a chemically inducible Na+ channel that appears to be voltage-dependent.

Astrocytes↗
PubMed1984

HCMR interviews physician administrator leaders. Interview by Michael J. Enright.

This interview departs from HCMR's usual format, interviewing several leaders in health care administration for their ideas on current economic pressures, the impact of competition and joint ventures, attitudes toward equity and capital formation, and competition between the interest of clinical medicine and the cost of care. The physician administrators interviewed hold senior administrative positions: Charles Edwards, President and Chief Executive Officer of Scripps Clinic and Research Foundation; Robert A. Henry, President and Chief Executive Officer of Swedish-American Corporation; William S. Kiser, Chairman of the Board of Governors at Cleveland Clinic Foundation; W. Eugene Mayberry, Chairman of the Board of Governors at Mayo Clinic; and Ronald P. Kaufman, Vice-President for Medical Affairs of George Washington University Hospital. All are members of the Board of Regents or Fellows of the American College of Physician Executives.

Economic Competition↗
PubMed1984

The effects of X irradiation on the cytoskeleton of rat alveolar macrophages in vitro.

The three-dimensional visualization of Triton X-100 resistant cytoskeletons has been used to demonstrate that an absorbed dose of 120 Gy from X rays causes a distinctive and reproducible alteration of the cytoskeleton of intact rat alveolar macrophages in vitro. The alteration has also been shown to be rapidly and completely "repaired" and to be apparently similar to alterations caused by colchicine but dissimilar to those caused by cytochalasin B. From these observations and those of other workers who have studied the irradiation of extracted microtubular proteins in vitro, we think it likely that microtubules rather than microfilaments are the radiosensitive component of the macrophage cytoskeleton.

Animals↗