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Shayna McKay

University of California, Los Angeles

Publishes on Atomic and Subatomic Physics Research, Advanced MRI Techniques and Applications, Salmonella and Campylobacter epidemiology. 14 papers and 568 citations.

14Publications
568Total Citations

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Top publicationsby citations

Morphine for the Relief of Breathlessness in Patients with Chronic Heart Failure—A Pilot Study
Miriam J. Johnson, Theresa A. McDonagh, Allan Harkness et al.|European Journal of Heart Failure|2002
Cited by 224

BACKGROUND: Chronic heart failure (CHF) patients can experience significant breathlessness despite maximum medication for their heart failure. Morphine has long been used to relieve symptoms in acute failure, but there is little evidence about this potentially useful palliative therapy in CHF. AIMS: To determine the efficacy of morphine for the relief of breathlessness in patients with CHF. METHOD: Ten out-patients with NYHA III/IV CHF entered a randomised, double-blind, placebo controlled, crossover pilot study. The active arm was 4 days of 5 mg oral morphine four times daily (2.5 mg morphine if creatinine > 200 micromol/l). There were 2 days wash-out between active and placebo arms. RESULTS: 6/10 patients indicated that morphine improved their breathlessness. On morphine, the median breathlessness score fell by 23 mm (P = 0.022) by day 2. The improvement was maintained. Sedation scores increased until day 3 (P = 0.013), reducing on day 4. Four patients developed constipation (P = 0.026). On placebo, there was no significant difference in breathlessness or sedation. One patient had constipation. There were no significant differences in either arm in nausea, quality of life scores, blood pressure, pulse, respiratory rate, or catecholamines. Brain natriuretic peptide fell in both arms; significantly in the morphine arm. CONCLUSION: Morphine relieves breathlessness due to CHF. A larger study is indicated.

Hyperpolarized 3He Ventilation Defects and Apparent Diffusion Coefficients in Chronic Obstructive Pulmonary Disease
Grace Párraga, Alexei Ouriadov, Andrea Evans et al.|Investigative Radiology|2007
Cited by 153

OBJECTIVE: Hyperpolarized 3He magnetic resonance imaging (3He MRI) at 3.0 Tesla of healthy volunteers and chronic obstructive pulmonary disease (COPD) patients was performed for quantitative evaluation of ventilation defects and apparent diffusion coefficients (ADC) and for comparison to published results acquired at 1.5 Tesla. The reproducibility of 3He ADC and ventilation defects was also assessed in subjects scanned 3 times, twice within 10 minutes, and again within 7 +/- 2 days of the first MRI visit. MATERIALS AND METHODS: Hyperpolarized 3He MRI was performed in 6 subjects. Two interleaved images with and without additional diffusion sensitization were acquired with the first image serving as a ventilation image from which defect score and volume were measured and the combination of the 2 images used to compute ADC maps and ADC histograms. RESULTS: He MRI at 3.0 Tesla showed increased mean ADC and ADC standard deviation for subjects with COPD compared with healthy volunteers (ADC healthy volunteer (0.24 +/- 0.12 cm2/s), mild-moderate COPD (0.34 +/- 0.14 cm2/s), and severe COPD (0.47 +/- 0.21 cm2/s), and these values were similar to previously reported results acquired at 1.5 Tesla. Reproducibility of mean ADC was high (coefficient of variation 2% in severe COPD, 3% in mild-moderate COPD, 4% in healthy volunteers) across all 3 scans. Higher same-day scan reproducibility was observed for ventilation defect volume compared with 1-week scan reproducibility in this small group of subjects. CONCLUSIONS: ADC values for emphysematous lungs were significantly increased compared with healthy lungs in age-matched subjects, and all values were comparable to those reported previously at 1.5 Tesla. Ventilation defect score and ventilation defect volume results were also comparable to results previously reported in COPD subjects Reproducibility of ADC for same-day scan-rescan and 7-day rescan was high and similar to previously reported results.

Value of theophylline treatment in patients handicapped by chronic obstructive lung disease.
Shayna McKay, CA Howie, Anne Thomson et al.|Thorax|1993
Cited by 102Open Access

BACKGROUND: It is still not certain whether it is worth using theophylline in addition to inhaled bronchodilators and corticosteroids to treat obstructive airways disease. This trial was designed to test whether the addition of prescribed theophylline in doses sufficient for sustained optimal steady state plasma concentrations would produce any detectable additional advantage in spirometric or functional variables in these handicapped patients. METHODS: A randomised, double blind, placebo controlled, crossover study of added theophylline treatment was aimed at steady state plasma concentrations of 10 and 17 mg/l, the dose being calculated individually by Bayesian parameter estimation and maintained for six weeks along with the patient's previously prescribed bronchodilators and steroids. Of 20 patients sequentially recruited, 15 provided data that could be analysed. All had chronic obstructive lung disease with a mean forced expiratory volume in the first second (FEV1) up to about 30% of the predicted value and gave no history of being treated with theophylline. The protocol included spirometry, whole body plethysmography, and treadmill exercise. Measurements also included steady state plasma theophylline concentrations and trapped gas volume. Quality of life was assessed by an established questionnaire method covering breathlessness in everyday activities, fatigue, emotional function, and control over the disease. RESULTS: Both target plasma concentrations were achieved. Improvements in peak flow (PEF; mean 20%), trapped gas volumes (38%), two stage vital capacity (15%), distances walked (48%), breathlessness in everyday activities (32%), and fatigue (18%) were found at the higher plasma concentration only. FEV1, forced vital capacity (FVC), emotional function, and control did not change. CONCLUSION: Theophylline treatment with sustained steady state concentrations about 17 mg/l provides worthwhile objective and subjective further benefits for patients handicapped by chronic obstructive lung disease when it is added to bronchodilators and corticosteroids.

Effects of staphylococcal products on locomotion and chemotaxis of human blood neutrophils and monocytes
Robert J. Russell, P. C. Wilkinson, R. J. McInroy et al.|Journal of Medical Microbiology|1976
Cited by 47Open Access

Following the attacks on the creators of the controversial satirical magazine Charlie Hebdo in Paris in January 2015, the shootings at a debate on free speech in Copenhagen, the punishment of the rights activist and blogger Raif Badawi in Saudi Arabia, and the subsequent massive civil mobilisation, the cultural field is forced to process the significance of these events and their wider implications for our work. In Paris and many other instances across continents, representation itself came under attack. Arguably, the field of representation has been in crisis for some time, yet the current context demands that we consider this crisis from ...

Age-Related Susceptibility of Mice to Staphylococcal Infection
Shayna McKay, J. P. Arbuthnott|Journal of Medical Microbiology|1979
Cited by 13

The virulence of six strains of staphylococci in experimental subcutaneous infection in mice of three age groups (3, 10 and 21 days) was studied. The results showed an age-related susceptibility to infection, in that the newborn mice were more susceptible than older mice to death and lesion formation. Resistance, i.e., ability to survive challenge of 10(7) c.f.u., developed at about 5 days. The strains used varied in toxin and enzyme pattern and there were marked differences in response to challenge as measured by mortality and lesion development. The Staphylococcus epidermidis strain was least virulent, while some strains of S. aureus produced lesions at low doses (10(4) c.f.u.). Two distinct types of lesion were observed, abscesses and necrotic lesions. Development of necrotic lesions appeared to be correlated with the ability to produce toxin in vitro.