Browsing by Subject "Dehydration (Physiology)"
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Item Effects of Short-Term Dehydration and Rehydration on Acoustic Measures of Voice(Texas Tech University, 1998-03) Dane, Rebecca LThe purpose of this study was to determine whether short-term dehydration (i.e., no fluid or food intake for a 10-hour period) and subsequent rehydration (i.e., 4-ounce fluid intake every 17 minutes over a period of 2 hours and 15 minutes) resulted in significant changes in acoustic measures of voice. Employing a within-subject, quasi-time series design, a total of 25 healthy subjects (3 males and 22 females) between the ages of 20 and 30 years participated in the study. Baseline data were established through speech samples obtained on four successive evenings and mornings. Speech samples consisted of phonating the randomly ordered vowels /a/, I'll, IvJ, and lol within the carrier phrase "Say /hAb_b/ again." During experimental procedures, speech samples were obtained at 17-minute intervals following intake of 4 ounces of water. It was hypothesized that the morning pretest samples would exhibit decreased fundamental frequency and greater values for jitter, shimmer, and harmonic-to-noise ratio across vowels due to decreased hydration levels. During post-tests, it was hypothesized that fundamental frequency values would increase and jitter, shimmer, and harmonic-to-noise ratio measures would decrease for all vowels over time as a function of increased hydration. Results indicated a significant (p < 0.01) main effect for vowel type across all acoustic measures; however, a significant (p < 0.01) main effect for time was only noted for fundamental frequency, jitter, and shimmer. Descriptive statistics revealed trends which supported the hypotheses for all vowels and acoustic measures with the exception of harmonic-to-noise ratio. Results of this study contribute to normative data and have implications for voice therapy and care of the professional voice.Item Physiological effects of water stress on two species of heteromyid rodents(Texas Tech University, 1992-05) Homan, Jacqueline AFew studies of desert rodents (Mammalia: Heteromyidae) have been designed to address the adaptive role of arginine vasopressin (AVP). The objectives of this study were to determine the effects of water stress on plasma and pituitary arginine vasopressin (AVP) and the Impact of increased hormone levels on blood and urine parameters. Adult males of two sympatric species of heteromyid rodents (Dipodomys ordii and Chaetodipus hispidus) were live-trapped on the Llano Estacado of western Texas and acclimated to laboratory conditions. Experimental groups, which were fed different diets for 15 days, included: water control (grain, carrots, and water); baseline control (grain and carrots); and water-stressed (grain only). Plasma and whole pituitary AVP concentrations, urine and plasma osmolalities, hematocrit, and weight changes were each compared among experimental groups. Kidneys were processed for AVP receptor studies. Two-way (species and treatments) analysis of variance for each variable revealed that the two species reacted differently to the treatments. Water-stressed C. hispidus had significantly greater concentrations of pituitary AVP (1.017 µg AVP/mg) compared to concentrations in D. ordii (0.088 jig AVP/mg). Dipodomys ordii had higher plasma AVP levels compared to those in C. hispidus. Urine osmolality increased significantly with dehydration in both species, but no significant difference existed between species. Values ranged from 1878 mOsm/kg In water controls to 3535 mOsm/kg In water-stressed C. hispidus, and from 1158 mOsm/kg to 3267 mOsm/kg for the same treatments in D. ordii. Compared to both control groups, values for plasma osmolality were higher in water-stressed D. ordii but lower in 0. hispidus. Hematocrit increased in both species with dehydration. Limited data indicated that receptor concentration in all treatment groups was higher for C. hispidus than for D. ordii. Together, data indicate that the aridadapted D. ordii appears to be more stressed by 15 days of dehydration than the more mesic-adapted C. hispidus