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Biomedical subjects

R G Thomas

Publications and source records attributed to R G Thomas.

158 records · Page 9Linked to original sources
PubMedDate not supplied

Analysis of longitudinal data in an Alzheimer's disease clinical trial.

Evidence of delayed progression is the primary mechanism for demonstrating therapeutic efficacy in clinical trials in Alzheimer's disease. In the major trials of therapeutic treatment of AD, to date, measures based on clinical judgement and cognitive performance, instead of mortality, have been used as the primary response measures. There is good reason for this since the course of the disease is quite long, and AD trials designed around mortality would require either very large sample sizes or very long follow-up in order to have adequate power. However, the evaluation of progression in AD using clinical markers is subject to a number of challenges often found in longitudinal databases, for example, missing data, floor and ceiling effects and non-linearity. Unfortunately, few of these issues are being addressed in the typical analysis of progression data. This paper explores these analytic issues in the context of the recently completed Alzheimer's Disease Cooperative Study trial of vitamin E and Selegeline in moderate AD patients.

Aged↗
PubMedDate not supplied

The pituitary-testicular axis at rest and during moderate exercise in males with diabetes mellitus and normal sexual function.

Hormonal studies of pituitary-testicular function in insulin-dependent diabetes mellitus were examined at rest and during moderate exercise to assess whether diabetes per se caused abnormalities of nocturnal penile tumescence and androgen function in men with normal sexual function. The present study compared 10 healthy men and eight men with Type I diabetes mellitus in whom normal sexual function was determined by clinical history. Urinary gonadotropin excretion, semen analysis and diurnal variation of serum glucose, prolactin, testosterone and free testosterone were determined in both groups. In addition, the serum levels of testosterone, free testosterone, prolactin, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) were measured at rest, during 45 minutes of exercise on a bicycle ergometer at 50% of the subjects previously determined maximal oxygen uptake (VO2 max) and during a 30-minute recovery period. Nocturnal penile tumescence and parameters of semen analysis were similar in both groups. Urinary FSH excretion and serum FSH were higher (P less than or equal to 0.01) in the diabetic subjects while urinary LH excretion was similar. Diurnal variation of serum prolactin, testosterone and free testosterone were similar in both groups. Exercise produced a significant (P less than or equal to 0.01) increase in maximal free and total testosterone in both groups without changes in serum FSH or LH. Prolactin increased significantly (P less than or equal to 0.01) during exercise in the diabetic group only. We conclude that, for the most part, the pituitary-testicular axis and nocturnal penile tumescence under basal conditions and the pituitary-testicular axis during moderate exercise are similar in healthy males and insulin-dependent diabetic males with normal sexual function.

Adolescent↗
PubMedDate not supplied

Partitioning the respiratory effects of airway citric acid and normal saline in lambs.

Aspiration is common in the intubated human neonate. Thus, the ventilatory and blood gas responses to citric acid and saline instillation into different airway sites were studied in ten awake, unanesthetised lambs, breathing spontaneously via a tracheostomy tube. With a system of balloons, 1 ml of saline or citric acid was placed selectively into the midtrachea, the laryngeal area, or the lower trachea (lower tr). Changes in minute ventilation (VE), after a 30 sec baseline period, were measured 30 sec and 1 and 2 min after the challenge. Arterial blood gas changes were measured at 30 sec and 2 min. Major increases in VE were seen only when saline or citric acid was instilled into the lower tr, the citric acid responses exceeding saline ones. The arterial oxygen tension (PaO2) fell after lower tr saline, whereas the arterial CO2 tension (PaCO2) fell with midtracheal saline instillation. A rise in pH and a fall in PaCO2 accompanied citric acid given into the lower tr. An initial rise in PaO2 after citric acid into the lower tr was followed by a return to baseline despite hyperventilation. The ventilatory and blood gas changes with saline and citric acid depend on the site of airway instillation.

Airway Resistance↗
PubMedDate not supplied

Quantifying behavioral disturbance in Alzheimer's disease patients.

In the course of a four-month study of interventions for behavioral disturbances in Alzheimer's disease (AD) patients, the following assessment instruments were examined for validity: the clinical global impression of change (CGIC), Cohen-Mansfield agitation inventory (CMAI); CERAD behavioral rating scale for dementia (BRSD), revised memory and behavioral problems checklist (RMBPC) and the agitated behavior in dementia scale (ABID). The four specific behavioral/agitation scales had excellent cross-sectional and longitudinal correlations with each other, suggesting high validity, but changes as indicated by CGIC scores did not correlate well with change scores on the other instruments. We conclude that specific behavioral instruments are preferable to the more general CGIC for detecting and quantifying behavioral disturbances in AD patients.

Aged↗