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Biomedical subjects

D Yates

Publications and source records attributed to D Yates.

At least 37 records · Page 2Linked to original sources
PubMed1999

Corticotropin-releasing hormone mimics stress-induced colonic epithelial pathophysiology in the rat.

We examined the effect of stress on colonic epithelial physiology, the role of corticotropin-releasing hormone (CRH), and the pathways involved. Rats were restrained or injected intraperitoneally with CRH or saline. Colonic segments were mounted in Ussing chambers, in which ion secretion and permeability (conductance and probe fluxes) were measured. To test the pathways involved in CRH-induced changes, rats were pretreated with hexamethonium, atropine, bretylium, doxantrazole, alpha-helical CRH-(9-41) (all intraperitoneally), or aminoglutethimide (subcutaneously). Restraint stress increased colonic ion secretion and permeability to ions, the bacterial peptide FMLP, and horseradish peroxidase (HRP). These changes were prevented by alpha-helical CRH-(9-41) and mimicked by CRH (50 microgram/kg). CRH-induced changes in ion secretion were abolished by alpha-helical CRH-(9-41), hexamethonium, atropine, or doxantrazole. CRH-stimulated conductance was significantly inhibited by alpha-helical CRH-(9-41), hexamethonium, bretylium, or doxantrazole. CRH-induced enhancement of HRP flux was significantly reduced by all drugs but aminoglutethimide. Peripheral CRH reproduced stress-induced colonic epithelial pathophysiology via cholinergic and adrenergic nerves and mast cells. Modulation of stress responses may be relevant to the management of colonic disorders.

Animals↗
PubMed1996

Reducing accident death rates in children and young adults: the contribution of hospital care. Steering Committee of the Major Trauma Outcome Study Group.

OBJECTIVE: To assess the contribution of trauma care to the recent decline in accident death rates among children and young people. DESIGN: Logistic regression modelling of temporal trends in the probability of death in patients admitted to hospital for the treatment of severe injury. SETTING: Hospitals participating the United Kingdom major trauma outcome study. SUBJECTS: 3230 patients with an injury severity score of 16 or more, who were admitted for more than three days, transferred or admitted to intensive care, or died from their injuries. MAIN OUTCOME MEASURES: Death or survival in hospital within three months of injury. RESULTS: Over the seven year period 1989-95 there was a substantial decline in the probability of death among children and young adults admitted to hospital after severe injury. The overall estimate of the reduction in the odds of death was 16% per year (odds ratio for the yearly trend 0.84; 95% confidence interval 0.79 to 0.89). This decline did not differ significantly between age groups. (0-4 years 0.79; 5-14 years 0.87; 15-24 years 0.83). CONCLUSIONS: Reductions in hospital case fatality have made an important contribution to reaching the Health of the Nation targets. The contribution of hospital care in the reduction of accident mortality should be taken into account in decisions about the allocation of resources to preventive and curative services.

Accidents↗
PubMed1996

Trauma care in China: challenge and development.

The People's Republic of China has significantly improved the general health of its people by a concerted effort in primary health care but trauma care and its prevention remains a problem. This paper provides an overview of the strengths and weaknesses of the trauma-care system in China and proposes a strategy for its future development. This includes public-health legislation, the integration of military and civilian practice to provide comprehensive care from the scene of the incident through to rehabilitation, medical audit, the introduction of postgraduate trauma-management training courses and international academic exchanges.

China↗
PubMed1995

Acute and chronic effects of cigarette smoking on exhaled nitric oxide.

Cigarette smoking is associated with an increased risk of respiratory tract infections, chronic airway disease, and cardiovascular diseases, all of which may be modulated by endogenous nitric oxide (NO). We have investigated whether cigarette smoking reduces the production of endogenous NO. We compared exhalations of 41 current cigarette smokers with normal lung function and 73 age-matched non-smoking controls. Peak exhaled NO levels were measured by a modified chemiluminescence analyzer. The effects of inhaling a single cigarette in smokers were also measured. In control subjects we also measured the effects of inhalation of NO itself and carbon monoxide, both constituents of tobacco smoke. Peak exhaled NO concentrations were significantly reduced in smokers (42 +/- 3.9 compared with 88 +/- 2.7 parts per billion in nonsmokers, p < 0.01), with a significant relation between the exhaled NO and cigarette consumption (r = 0.77, p < 0.001). Smoking a single cigarette also significantly (p < 0.02), but transiently, reduced exhaled NO. Inhalation of carbon monoxide and NO had no effect on exhaled NO in normal subjects. Cigarette smoking decreased exhaled NO, suggesting that it may inhibit the enzyme NO synthase. Since endogenous NO is important in defending the respiratory tract against infection, in counteracting bronchoconstriction and vasoconstriction, and in inhibiting platelet aggregation, this effect may contribute to the increased risks of chronic respiratory and cardiovascular disease in cigarette smokers.

Administration, Inhalation↗
PubMed1995

Increased nitric oxide in exhaled air of normal human subjects with upper respiratory tract infections.

Viral infection may induce the expression of nitric oxide (NO) synthase, resulting in increased NO formation that has an antiviral effect. NO may be produced by various cells of the upper and lower respiratory tract, and may be detected in the exhaled air. We have studied the levels of exhaled NO in 18 normal subjects during symptomatic upper respiratory tract infections and during recovery 3 weeks later. Exhaled NO was measured using a modified chemiluminescence analyser. At the time of symptoms of upper respiratory tract infection, the peak exhaled NO values were 315 +/- 57 ppb (mean +/- SEM) and decreased to 87 +/- 9 ppb during recovery. Recovery values of exhaled NO were similar to those reported in age-matched normal control subjects (88 +/- 3 ppb, n = 72). These findings suggest that symptomatic upper respiratory tract infections markedly increase the concentration of NO in exhaled air. This may reflect the induction of nitric oxide synthase (NOS) in upper and lower respiratory tract, and may be relevant to viral exacerbations of asthma.

Adult↗
PubMed1994

Increased nitric oxide in exhaled air of asthmatic patients.

Nitric oxide (NO) gas is produced by various cells within the lower respiratory tract, including inflammatory and epithelial cells, and is detectable in the exhaled air of normal human subjects. We have measured exhaled NO in patients with asthma, since several cell types that are activated in asthma can produce NO after induction. NO was measured reproducibly by a slow vital capacity manoeuvre and an adapted chemiluminescence analyser. NO was detectable in exhaled air of 67 control subjects (mean peak concentration 80.2 [SE 4.1] ppb) and was significantly reduced by inhalation of the specific NO synthase inhibitor NG-monomethyl-L-arginine. 61 non-steroid-treated asthmatic subjects had significantly higher peak expired NO concentrations than controls (283 [16] ppb, p < 0.001) but 52 asthmatic patients receiving inhaled corticosteroids had levels similar to controls (101 [7] ppb). High exhaled NO concentrations in asthmatic patients may reflect induction of NO synthase, which is known to be inhibited by steroids. Measurement of exhaled NO concentrations may be clinically useful in detection and management of cytokine-mediated inflammatory lung disorders.

Adrenal Cortex Hormones↗
PubMed1993

Adherence and fibronectin binding are environmentally regulated in the group A streptococci.

The ability of the pathogenic Gram-positive bacterium Streptococcus pyogenes (group A streptococcus) to bind fibronectin and adhere to respiratory epithelial cells is dependent on a surface protein called protein F. In this study, we have examined the regulation of expression of protein F and have shown that it is environmentally regulated in response to alterations in atmosphere. In six recent clinical isolates expression of protein F was repressed during growth under reduced concentrations of O2. Expression in an anaerobic environment was induced by both superoxide-generating and redox-altering reagents. However, regulation did not involve mry, a gene that controls expression of several streptococcal surface proteins. Protein F was constitutively expressed in one of two laboratory-passaged strains analysed, and in a complementation analysis using an allele of the gene that encodes protein F (prtF) cloned from a regulated strain and expressed in a constitutive strain, the constitutive phenotype was shown to be dominant in trans. Regulation, as monitored by fusion of prtF to a promoterless chloramphenicol acetyltransferase gene, involved transcriptional control. Environmentally induced alterations in protein F expression affected the ability of the bacterium to adhere to epithelial cells, which suggests that the ability to regulate expression of protein F may be important during infection.

Bacterial Adhesion↗
PubMed1989

Rear seat belts.

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Adult↗
PubMed1988

Steady-state visual evoked potentials to asymmetrical contrast.

The temporal frequency components in the steady-state visual evoked response (VEP) depend on the method of stimulus presentation; a first harmonic is generated to "on-off" patterns while a second harmonic occurs to both "on-off" and counterphase patterns. This study examined the VEP response in humans to patterns between these two extremes. In the main experiment, a 1 c/d sinusoidal grating was phase reversed sinusoidally at 8 Hz. The DC offset, however, was adjusted such that two different levels of peak contrast occurred during a temporal cycle. Within this context, a counterphase pattern would represent complete contrast symmetry and an "on-off" pattern would represent maximum contrast asymmetry during a temporal cycle. With this manipulation, the a) integrated luminance change; b) local luminance change; and c) total contrast remained constant. Only mean contrast varied. The amplitude of the first harmonic strongly depended on mean contrast. The amplitude and phase of the second harmonic, however, changed little across experimental conditions suggesting a dependence on one or more of the above three listed stimulus attributes which remained constant. In a supplementary experiment, this phase constancy was confirmed using other temporal frequencies.

Adult↗