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Age-Associated Changes In The Kinetics Of Ventilation And Pulmonary Gas Exchange, Mark Anthony Babcock
Age-Associated Changes In The Kinetics Of Ventilation And Pulmonary Gas Exchange, Mark Anthony Babcock
Digitized Theses
The purpose of these studies was to examine ageing effects on the dynamics of pulmonary gas exchange and ventilation during the transition from light to moderate work. In the first study maximal oxygen uptake (VO{dollar}\sb2{dollar}max), ventilation threshold (VeT), the time constant for VO{dollar}\sb2{dollar} ({dollar}\tau\sp\prime{dollar}VO{dollar}\sb2{dollar}), and efficiency were determined from a ramp forcing test in eighty-three males aged 30 to 84y. The results showed a decline in VO{dollar}\sb2{dollar}max with age of {dollar}-{dollar}0.037 1{dollar}\cdot{dollar}min{dollar}\sp{lcub}-1{rcub}{dollar} per year. The VeT also declined with age but at one-third the rate of loss of the VO{dollar}\sb2{dollar}max. The {dollar}\tau\sp\prime{dollar}VO{dollar}\sb2{dollar} increased with age; the older group (60+y) had …
31-Phosphorous, Nuclear Magnetic Resonance Spectroscopy Studies Of Exercising Human Muscle, Gregory D. Marsh
31-Phosphorous, Nuclear Magnetic Resonance Spectroscopy Studies Of Exercising Human Muscle, Gregory D. Marsh
Digitized Theses
Phosphorous 31, nuclear magnetic resonance spectroscopy {dollar}(\sp{lcub}31{rcub}{dollar}P NMRS) was used as a non-invasive probe of forearm muscle metabolism in three studies of healthy men and women. Specific objectives of the studies were to: (1) observe the changes in high energy phosphates and intracellular pH in muscle, during a ramp exercise protocol, (2) study the effect of endurance training on muscle metabolism and evaluate the utility of the forearm ramp test as a means to assess muscle oxidative capacity, and (3) describe the kinetics of phosphocreatine (PCr) and inorganic phosphate (Pi) metabolism during the on and off transient response to moderate …
The Effects Of Gastrin Releasing Peptide In Fetal Sheep, Pregnant Sheep And Non Pregnant Sheep, Pamela Elizabeth Houghton
The Effects Of Gastrin Releasing Peptide In Fetal Sheep, Pregnant Sheep And Non Pregnant Sheep, Pamela Elizabeth Houghton
Digitized Theses
These studies examined the hypothesis that GRP stimulates insulin release from the endocrine pancreas of ovine fetuses. This could occur due to the action of GRP directly within the fetal compartment or due to indirect effects of GRP on glucose and insulin concentrations in the maternal compartment which in turn influences the availability of glucose for transplacental transfer to the fetus and hence produce alterations in fetal insulin release.;The studies performed provided the following results: (1) IR-GRP was detectable in nerves of the GI tract and in the systemic circulation but not in the pancreas of fetal and adult sheep; …
Myosin Transformation In Thyrotoxic Rat Soleus Muscle, Margaret Mary Sopper
Myosin Transformation In Thyrotoxic Rat Soleus Muscle, Margaret Mary Sopper
Digitized Theses
Male Sprague-Dawley rats were injected with 300{dollar}\mu{dollar}g/kg body weight of Triiodo-L-thyronine (T{dollar}\sb3{dollar}) and L-thyroxine (T{dollar}\sb4{dollar}) on alternate days over a 28-day treatment period. Thyrotoxicosis was confirmed by increased serum T{dollar}\sb3{dollar} levels and a pronounced ventricular hypertrophy (p {dollar}\le{dollar} 0.05 after 5 days). The effects of thyroid hormone on isometric contractile properties of the slow-twitch soleus muscle were studied in situ after 2, 5, 7, 15, 21 or 28 days. Time to peak tension (TPT) and one half relaxation time (1/2 RT) were significantly reduced after 5 days (T-5, p {dollar}\le{dollar} 0.05) and reached 56.7% and 51.1% of age-matched control values …
The Phosphoinositide Second Messenger System And The Regulation Of The Release Of Growth Hormone From Purified Rat Somatotrophs, Michelle Brigid French
The Phosphoinositide Second Messenger System And The Regulation Of The Release Of Growth Hormone From Purified Rat Somatotrophs, Michelle Brigid French
Digitized Theses
The release of growth hormone (GH) from the somatotrophs of the anterior pituitary is controlled by two hypothalamic hormones growth hormone-releasing factor (GRF) and somatostatin (SRIF). The former stimulates, while the later inhibits the release of GH. cAMP and Ca{dollar}\sp{lcub}2+{rcub}{dollar} are second messengers for GRF. Previous reports suggested that the phosphoinositide second messenger system was an additional pathway for GRF. Our purpose was to examine the role of this system in GRF action. We used perifused dispersed anterior pituitary cells and purified somatotrophs from male rats to ask: (1) Does activation of protein kinase C stimulate the release of GH …
Regulation Of Porcine Thecal Cell Steroidogenesis By Locally Produced Factors, Heidi E. Engelhardt
Regulation Of Porcine Thecal Cell Steroidogenesis By Locally Produced Factors, Heidi E. Engelhardt
Digitized Theses
Regulation of steroidogenesis (measured by radioimmunoassay) by peptides produced within the ovary was investigated in monolayer cultures of porcine thecal cells (TC). In serum-free cultures LH but not FSH stimulated accumulation of androstenedione (Ad) and progesterone (P). No further accumulation of either steroid occurred after 19h. Addition of fetal bovine serum (FBS; optimal at 1%) maintained steroidogenesis for 3-4 days, but Ad production declined, and, in the presence of LH, P production increased. IGF-I plus LH markedly enhanced P production, an effect most pronounced after 3-4 days of treatment, and not associated with increases in DNA per well. Changes in …