published_or_final_version / abstract / toc / Pharmacology / Doctoral / Doctor of Philosophy

published_or_final_version / Pharmacology / Master / Master of Philosophy

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The purpose of this study was to compare the concentration of and the time to peak blood lactate following three 90-s cycle ergometer tests--intermittent all-out (Int-A), continuous all-out (Cont-A), and continuous constant (Cont-C), and to compare group peak lactate to blood lactate at individual peak time. Eight fingertip blood samples were drawn between 1 and 12min post-exercise. Subjects were university hockey players (n = 19) and physical education students (n = 19). The two all-out tests had a higher peak concentration than the Cont-C test (P $<$ 0.05). The Int-A test had an earlier peak than the two continuous tests (P $<$ 0.05) but this difference vanished if peak time was measured from the onset of the tests. A number of sampling times had lactate concentrations similar to the individual peak concentration (P $<$ 0.05): (1) 1, 2, 3, and 4min for Int-A; (2) 2, 3, 4, 5, and 6min for Cont-A; (3) 2 and 4min for Cont-C.

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To investigate the relationship between pulmonary diffusion limitation, ventilation-perfusion (VA/Q) mismatch, pulmonary transit times (PTT) and pulmonary gas exchange during exercise, 10 highly trained male athletes (age=26.4±4.4 years, Height=185.5±5.3cms, Weight=78.2±8.6 kg, V 02max=5.15±0.521-min-1) under went exercise testing at rest (R) and 150W, 300W and maximal exercise (372±22W), corresponding to an oxygen consumption (V0₂) of 0.41±0.09, 2.16±0.17, 4.32±0.35 and 5.13±0.50 1-min-1respectively, while trace amounts of six inert gases were infused via a peripheral vein. Arterial blood samples, mixed expired gas samples and metabolic data were obtained. Observed alveolar arterial difference ([A-a]D0₂(0)was calculated according to the alveolar gas equation. Indices of VA/Q mismatch: LogSDi and Log SDa and predicted [A-a]D0₂([A-a]DO₂(p)) were derived from 50 compartment model analysis of retentions and excretions of the inert gases. Additional indices of '/A/I,) mismatch: DISPR*, DISPE and DISPR*_E and inert gas alveolar difference ([A-a]D, R(A-a)D and E(A-a)D) were obtained directly from the inert gas data. One to two weeks later, the subjects underwent first pass radionuclide angiography using a Siemens ZLC wide field of view gamma camera. Following in vitro labeling with 99mTechnecium, 5-10 ml of the subject's blood, containing 10-20 mCi of activity, were injected at rest. First pass and post-static data were obtained on an ADAC 3003 computer and cardiac output was calculated using the Stewart Hamilton equation. PTT was determined using deconvolution and centroid methods. Gated radionuclide angiography was then performed at rest, 150, and 300W. On a separate occasion, first pass cardiac outputs and pulmonary transit times were obtained at maximal exercise. Mean arterial partial pressure of 0₂ (Pa0₂) decreased significantly from rest to 150W , and from 150 to 300W to a low value of 86±9 torn, before increasing to near resting values at maximal exercise. [A-a]D0₂(3) increased across each exercise levels however only the increase from 150 to 300 W was significant. The overall and perfusion-related indices of VA/Q mismatch showed a significant increase with exercise, mainly as a result of increasing perfusion of areas of high VA/Q [A-a]D0₂(0 was greater than predicted, becoming significant during heavy exercise, indicating diffusion limitation. Cardiac output increased from 6.9±0.9 1-min-1 (R) to 25.2±2.5 1-min-1 at 300W and 33.3±3.7 1-min-1 at maximal exercise. End diastolic volume increased from R to heavy exercise (p < 0.001), accompanied by a decrease in end systolic volume (p =0.05). Stroke volume and ejection fraction also increased significantly from R to 300W (p <0.001). Deconvolution PTT decreased from 9.32±1.41 s at rest to 2.91±0.30 s during max exercise and was highly correlated with centroid PTT both at rest (r=0.99, p<0.001) and during maximal exercise (r=0.96, p<0.001). PTT during maximal exercise was significantly correlated with Pa0₂ (1=0.65, p<0.05) and [A-a]D0₂(0)_[A-a]D0₂(p) (r=-0.60, p<0.05). Calculated pulmonary blood volume increased during maximal exercise by 57% over resting values to over 25% of total blood volume and when corrected for body surface area correlated significantly with Pa0₂ (r=0.69, p<0.05). There was a significant correlation between (A-a)D, PTT, the ventilatory equivalent for CO₂ and Pa0₂ during maximal exercise (r=0.94, p<0.01) allowing prediction of over 80% of the variance in Pa0₂ between subjects. These data indicate that highly trained athletes develop VA/Q mismatch accompanied by diffusion limitation during maximal exercise. Observed decrease in Pa0₂2 during high intensity exercise is the result of a complex interaction between VA/Q mismatch, hypoventilation and diffusion limitation secondary to shortened pulmonary transit.

Glycation is a series of chemical interactions occurring in food and biological systems between reducing sugars and proteins leading to the formation of Advanced Glycation End products (AGEs). Ingestion of dietary AGEs and/or their formation in-vivo are mainly associated with cardiovascular and other age-related diseases and complications of long term diabetes. Potential strategies to prevent AGE formation can help to reduce risk factors associated with thermal processing of many foods. The overall objective of this research was focused on the identification of potential AGE inhibitors and investigation of their activity in glucose and ribose-based model systems containing lysozyme. The carboxylic acid functional group was chosen as a potential candidate based on their ability to interact with Schiff bases in addition to their ability to form amide bonds and carboxylate salts with the lysine side chains of proteins. The model systems were incubated with and without selected carboxylic acids (maleic, acetic, oxalic and citraconic) at 50&deg;C for 12, 24 and 48h at pH 6.5. The effect of carboxylic acids on the glycation of lysozyme was studied by electrospray ionization mass spectrometry (ESI-MS). The experimental results showed that none of the carboxylic acids were able to form amide linkages with lysozyme under the experimental conditions and only maleic acid was able to form carboxylate salts, however, oxalic acid was the only acid able to interact with the Schiff base and form 1,3-oxazolidine-4,5-dione intermediate and thus hinder its rearrangement into Amadori product and consequently inhibit glycation. As a result the percentage of free or unreacted lysozyme was the highest in oxalic acid model systems (9.4% in the case of glucose, 7.1% in the case of ribose system) and was even higher than the control systems (6.0% in the case of glucose, 1.2% in the case of ribose system) of both glucose and ribose. In addition, all carboxylic acids were able to modify the relative distribution of different glycoforms generated during the incubation period however oxalic acid was the most efficient in shifting the distribution of glycoforms to lower molecular weight clusters which can additionally contribute to its anti-glycation activity.

The scientific study of sex has developed significantly since the inception of psychophysiological methods to assess sexual arousal. Sexual psychophysiology involves assessing the physiological activation of the sexual response system, in addition to mental, behavioral, and emotional processes or experiences (Rosen & Beck, 1988). Measures of sexual arousal are reviewed in Chapter One. Chapter Two describes a study testing the validity of the most commonly used measure of genital arousal in women, vaginal photoplethysmography. Results indicate that vaginal photoplethysmography is sensitive to sexual arousal only, and that there are important sex differences in patterns of physiological arousal to sexual stimuli. Directions for future research are discussed. / x, 176 leaves ; 29 cm.