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Biomedical subjects

C Burgess

Publications and source records attributed to C Burgess.

At least 109 records · Page 6Linked to original sources
PubMed1990

The airways effects of inhaled chlorbutol in asthmatic subjects.

Chlorbutol is an antibacterial and antifungal agent incorporated in terbutaline (Bricanyl) nebulizer solution. Ten stable atopic asthmatic subjects undertook bronchial challenge testing, according to a double-blind protocol. Patients inhaled doubling concentrations of either methacholine (0.13-4.0 mg.ml-1) or chlorbutol (0.16-5.0 mg.ml-1) for 2 min until the forced expiratory volume in one second (FEV1) had fallen by 20% from baseline. If this had not occurred following the administration of the final concentration, then this highest concentration was repeated for 4 min. The nine subjects completing the study had a geometric mean provocation concentration producing a 20% fall from baseline FEV1 (PC20) methacholine of 0.16 mg.ml-1 (range less than 0.125-0.475 mg.ml-1). After inhalation of 2.5 mg.ml-1 chlorbutol one subject experienced a fall in FEV1 greater than 20%. In the remaining eight subjects, inhalation of chlorbutol did not affect airway calibre. We conclude that chlorbutol, in the concentration present in Bricanyl nebulizer solution, has no clinically significant effect on airway calibre.

Adult↗
PubMed1989

Free sphingosine formation from endogenous substrates by a liver plasma membrane system with a divalent cation dependence and a neutral pH optimum.

Long-chain (sphingoid) bases may serve as another category of "lipid second messenger" because they inhibit protein kinase C and affect multiple cellular functions. Free sphingosine has been found in rat liver (Merrill, A. H., Jr., Wang, E., Mullins, R. E., Jamison, W. C. L., Nimkar, S., and Liotta, D. C. (1988) Anal. Biochem. 171, 373-381); hence, this study determined if liver plasma membranes contain free long-chain bases and have the ability to form them from endogenous enzymes and substrates. Isolated plasma membranes contained 0.45 nmol of sphingosine/mg of protein which, based on the recovery of the membranes, was equivalent to 3.5 +/- 1.2 nmol/g of liver and at least half of the total free sphingosine in liver. When the membranes were incubated at 37 degrees C, the amount increased at an initial rate of 5-25 pmol/min/mg, resulting in a 2-3-fold increase over an hour. Sphingosine formation required divalent cations, was optimal at neutral to alkaline pH, and was temperature-dependent. Activities with these characteristics were not identified in microsomes or lysosomes (lysosomal activities with acidic pH optima were detected, however); hence, they appear to reflect a separate plasma membrane system. Sphingosine formation was stimulated by ceramides either added exogenously or formed endogenously by treating the membranes with sphingomyelinase (but not endoglycoceramidase). Sphingomyelin hydrolysis to ceramide was also observed during incubation of the plasma membranes alone. Some of the properties of this system resembled the neutral sphingomyelinase and ceramidase activities of liver. While the physiological significance of this endogenous sphingosine is not known, this system has the appropriate subcellular location to provide sphingosine as a participant in signal transduction.

Animals↗
PubMed1989

Prescribed fenoterol and death from asthma in New Zealand, 1981-83: case-control study.

A case-control study was conducted to examine the hypothesis that fenoterol by metered dose inhaler (MDI) increases the risk of death in patients with asthma. The case group comprised 117 patients aged 5-45 who died of asthma between August, 1981, and July, 1983. For each case, 4 controls, matched for age and ethnic group, were selected from asthma admissions to hospitals to which the cases themselves would have been admitted, had they survived. The relative risk of asthma death in patients prescribed fenoterol by MDI was 1.55 (95% CI 1.04-2.33, p = 0.03). The possibility of confounding or effect modification by severity was assessed by consideration of subgroups defined by markers of asthma severity. The fenoterol MDI relative risk was 2.21 (95% CI 1.26-3.88, p = 0.01) in patients prescribed three or more categories of asthma drugs, 2.16 (95% CI 1.14-4.11, p = 0.02) in patients with a hospital admission for asthma during the previous 12 months, and 6.45 (95% CI 2.72-15.3, p less than 0.01) in patients prescribed oral corticosteroids at time of death or admission. In the group of patients with the most severe asthma (defined by a hospital admission during the previous year and prescription of oral corticosteroids) the fenoterol MDI relative risk was 13.29 (95% CI 3.45-51.2, p less than 0.01). After adjustment for severity, no other asthma treatment commonly used in New Zealand seemed to be associated with an increased risk of asthma death. Not all sources of bias can be definitely excluded; however, when considered together with other epidemiological and experimental evidence, these findings are consistent with the hypothesis that use of fenoterol by MDI increases the risk of death in severe asthma.

Acute Disease↗
PubMed1989

Context and lexical access: implications of nonword interference for lexical ambiguity resolution.

To eliminate potential "backward" priming effects, Glucksberg, Kreuz, and Rho (1986) introduced a variant of the cross-modal lexical priming task in which subjects made lexical decisions to nonword targets that were modeled on a word related to either the contextually biased or unbiased sense of an ambiguous word. Lexical decisions to nonwords were longer than controls only when the nonword was related to the contextually biased sense of the ambiguous word, leading Glucksberg et al. to conclude that context does constrain lexical access and that the multiple access pattern observed in previous studies was probably an artifact of backward priming. We did not find nonword interference when the nonword targets used by Glucksberg et al. were preceded by semantically related ambiguous or unambiguous word primes. However, we did replicate their sentence context results when the ambiguous words were removed from the sentences. We conclude that the interference obtained by Glucksberg et al. is due to postlexical judgements of the congruence of the sentence context and the target, not to context constraining lexical access.

Adult↗
PubMed1989

Cardiovascular and hypokalaemic effects of inhaled salbutamol, fenoterol, and isoprenaline.

The cardiovascular and hypokalaemic effects of equal doses of inhaled fenoterol, isoprenaline and salbutamol were compared in eight healthy male volunteers, in a double blind, placebo controlled study. Increasing doses of 400, 600, and 800 micrograms were given from a metered dose inhaler at 15 minute intervals, followed by measurements of heart rate, blood pressure, total electromechanical systole (as a measure of inotropic response), QTc interval, and plasma potassium concentration. After repeated inhalation, fenoterol resulted in significantly greater chronotropic, electrocardiographic, and hypokalaemic effects than either isoprenaline or salbutamol. The maximum inotropic effect of fenoterol was similar to that of isoprenaline.

Administration, Inhalation↗
PubMed1989

The cardiovascular effects of inhaled fenoterol alone and during treatment with oral theophylline.

We have investigated whether oral theophylline potentiated the cardiovascular effects of fenoterol administered by metered-dose inhaler. Eight healthy subjects were investigated on four occasions. On successive days (1 and 2), the subjects were given doses of 400 micrograms, 600 micrograms, and 800 micrograms of fenoterol at 15-minute intervals (total dose, 1.8 mg) or matched placebo. Systolic time intervals, blood pressure, and the ECG were recorded at baseline and five minutes after each inhalation. Thereafter, the subjects were treated with slow-release theophylline for eight days. On days 9 and 10, the procedures on days 1 and 2 were repeated. The order of treatment was applied according to a crossover Latin-square design. The effects after theophylline alone were no different from placebo. Theophylline potentiated those hemodynamic effects of fenoterol due to enhanced cardiac sympathetic tone (mean +/- SE) as measured by a decrease in Q-S2I (-41.6 +/- 7.6 ms vs -27.3 +/- 5.9 ms; p = 0.0004), an increase in systolic BP (23.5 +/- 2.8 mm Hg vs 9.0 +/- 5.3 mm Hg; p = 0.00001), and an increase in heart rate (15.8 +/- 1.6 bpm vs 9.1 +/- 3.7 bpm; p = 0.0013). The responses mediated by beta 2-adrenergic receptor stimulation, namely, a decrease in PEP and diastolic BP, were not potentiated. Although fenoterol prolonged the Q-Tc interval and decreased T-wave amplitude, these effects were not potentiated by theophylline. Oral theophylline potentiates the positively inotropic and chronotropic effects of fenoterol.

Administration, Inhalation↗
PubMed1988

Psychological response to cancer diagnosis--I. Correlations with prognostic variables.

A prospective, multidisciplinary study of 168 newly diagnosed patients with early breast cancer and Hodgkin's or non-Hodgkin's lymphoma was conducted. Psychological assessments were conducted at 3 and 12 months following diagnosis and correlated with clinical and pathological variables. There was no statistical association between psychological response to breast cancer and any other prognostic variable measured. In lymphoma patients of both groups there was evidence of greater psychiatric morbidity in those with more advanced disease and those who failed to respond to treatment. However there was also no statistical association between any cognitive response category and known prognostic variables. There was no evidence that the patient's gender or type of tumour affected their overall mental adjustment to cancer and the effect described in breast cancer may apply to all types of malignant disease.

Adaptation, Psychological↗
PubMed1988

Psychological response to cancer diagnosis--II. Evidence for coping styles (coping styles and cancer diagnosis).

One hundred and seventy-eight newly diagnosed patients with breast cancer, non-Hodgkin's or Hodgkin's lymphoma were studied with respect to their cognitive responses to cancer diagnosis. These were examined in relation to anxiety, depression and health locus of control as well as to clinical-pathological variables. Data analysis of cognitive responses alone did not confirm the existence of mutually exclusive categories of response. Analysis of cognitive responses and the other psychological variables combined, however, revealed that four broad coping 'styles' could be delineated: 'positive/confronting', 'fatalistic', 'hopeless-helpless' and 'denial/avoidance', which corresponded to our previously described categories. Lower psychological morbidity was associated with a positive/confronting response to diagnosis and with high internal locus of control, while higher anxiety and depression scores were associated with a hopeless-helpless response to diagnosis and with low internal locus of control. The evidence for coping 'styles' is discussed as well as the implications of the results for the psychological management of cancer patients.

Adaptation, Psychological↗
PubMed1988

Cerebral hemispheric mechanisms in the retrieval of ambiguous word meanings.

Targets related to ambiguous primes were projected to the left and right visual fields in a lexical priming experiment with stimulus onset asynchronies (SOA) of 35 and 750 msec. Right visual field results were similar to our earlier results with central projection (G. B. Simpson & C. Burgess, 1985, Journal of Experimental Psychology: Human Perception and Performance, 11, 28-39). Facilitation was found for the more frequent meaning at both SOAs and a decrease in facilitation for the less frequent meaning at the longer SOA. In contrast, left visual field results indicated a decay of facilitation for the more frequent meaning at the longer SOA, while activation for the subordinate meaning increased. Results suggest that, while automatic processing occurs in both hemispheres, only the left hemisphere engages in controlled processing of ambiguous word meanings. In addition, the present results support the idea that the right hemisphere has a special role in ambiguity resolution and that the right hemisphere lexicon possesses a richer endowment than earlier thought.

Adult↗
PubMed1988

Development of a questionnaire measure of adjustment to cancer: the MAC scale.

This paper describes the development of a self-rating scale to measure adjustment to cancer. The Mental Adjustment to Cancer (MAC) Scale has been completed by 235 patients with various types and stages of cancer. It is easily understood by, and acceptable to, patients. Data relating to reliability and internal consistency indicate that the MAC scale is a valuable research tool for clinical studies of patients' psychological adjustment to cancer.

Adaptation, Psychological↗
PubMed1987

Stress and cancer.

Stress is a term that has been variously defined in the literature. In the context of research into psychophysiological aspects of cancer, 'stress' usually refers to stressful events occurring in people's lives, such as bereavement or unemployment. The effects of stress in terms of psychological morbidity and physical illness are being studied more and more. Experimental work has been conducted using animals but the results are contradictory and inconclusive. It is postulated that the effects of stress are mediated hormonally or immunologically, and there is evidence in support of this view from both animal experiments and human studies. Other mechanisms may also exist. Observations that stress is implicated in the onset of cancer have been traced back to the sixteenth and seventeenth centuries. Early studies were methodologically flawed, however, and results from recent, more carefully controlled investigations have not supported consistently the connection between stress and cancer. The methodological problems to be overcome in this area are still enormous, not least that of causality: because the data of onset of malignancy is uncertain, it is impossible to know whether a stressful event preceded or followed the genesis of cancer. Recurrence of cancer is easier to date and more amenable to study. The contributory role of stress in recurrence or reactivation of tumour growth may be a more fruitful line of inquiry. Different methods for measuring stress are available. Questionnaires which patients complete themselves have been criticized on the grounds that they ignore the meaning and context of stressful events, and because their scoring systems imply additivity. Interview methods are superior and reliable, although more costly and time consuming. Studies that seek to measure the effects of stress on the course of cancer should control for intervening variables such as personality and social support.

Animals↗
PubMed1985

Analysis of neomycins A, B and C by high-performance liquid chromatography with post-column reaction detection.

The analysis of the antibiotics neomycins A, B and C was investigated. The separation of the components was studied using reversed-phase and reversed-phase ion-pair chromatography. The optimum separation was obtained utilizing a Lichrosorb RP-2 column with a mobile phase consisting of 75 mg/l sodium dodecyl sulphate, 0.5M Na2SO4 and 0.015 M sodium acetate buffer at pH 7.0. Using this mobile phase, baseline separation was obtained for all three compounds in approximately 20 min. Detection was via post-column derivatization of the analytes with ortho-phthalaldehyde in the presence of mercaptoethanol to form fluorescent iso-indole products. This system is applied to the analysis of a number of formulated products containing neomycin.

Journal Article↗