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At least 127 records · Page 7Linked to original sources
PubMed2005

Outcome of accelerated radiotherapy alone or accelerated radiotherapy followed by exenteration of the nasal cavity in dogs with intranasal neoplasia: 53 cases (1990-2002).

OBJECTIVE: To compare long-term results of radiotherapy alone versus radiotherapy followed by exenteration of the nasal cavity in dogs with malignant intranasal neoplasia. DESIGN: Retrospective study. ANIMALS: 53 dogs with malignant intranasal neoplasia. PROCEDURE: All dogs underwent radiotherapy consisting of administration of 10 fractions of 4.2 Gy each on consecutive weekdays. For dogs in the surgery group (n=13), follow-up computed tomography was performed, and dogs were scheduled for surgery if persistent or recurrent tumor was seen. RESULTS: Perioperative complications for dogs that underwent surgery included hemorrhage requiring transfusion (2 dogs) and subcutaneous emphysema (8). Rhinitis and osteomyelitis-osteonecrosis occurred significantly more frequently in dogs in the radiotherapy and surgery group (9 and 4 dogs, respectively) than in dogs in the radiotherapy-only group (4 and 3 dogs, respectively). Two- and 3-year survival rates were 44% and 24%, respectively, for dogs in the radiotherapy group and 69% and 58%, respectively, for dogs in the surgery group. Overall median survival time for dogs in the radiotherapy and surgery group (477 months) was significantly longer than time for dogs in the radiotherapy-only group (19.7 months). CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that exenteration of the nasal cavity significantly prolongs survival time in dogs with intranasal neoplasia that have undergone radiotherapy. Exenteration after radiotherapy may increase the risk of chronic complications.

Animals↗
PubMed2004

Adjusting muscle function to demand: joint work during acceleration in wild turkeys.

We measured the net work performed at hind limb joints in running turkeys to determine the source of mechanical power for acceleration. We tested the hypothesis that net mechanical work per step increases in proportion to acceleration at all four major hind limb joints (hip, knee, ankle and tarsometatarsal-phalangeal joint). This hypothesis was based on the idea that all hind limb muscles should contribute mechanical work to maximize performance during accelerations, and a previous study that indicated the mechanical power output of the entire turkey hind limb musculature was remarkably high. We used high-speed video and force-plate measurements to measure joint moment, velocity and power output during single foot-contacts of running accelerations. By measuring steps in which the animals were relatively more or less motivated to accelerate, we obtained data for a range of accelerations, all at approximately the same running speed. Net joint work per step increased at the hip and ankle as a function of acceleration. Hip net work per unit body mass was 0.12+/-0.09 J kg(-1) averaged over the five lowest accelerations (-0.22+/-0.08 m s(-2)), and 0.87+/-0.20 J kg(-1) for the five highest accelerations (4.86+/-0.27 m s(-2)). Ankle work was -0.21+/-0.11 J kg(-1) for the lowest accelerations and 0.71+/-0.28 J kg(-1) for the highest. The high work output at the ankle is consistent with the idea that elastic mechanisms function to increase muscle work during acceleration. The work performed at the knee and tarsometatarsal-phalangeal joint was independent of acceleration in a step. These results support the idea that hip and ankle extensors contribute significantly to the work necessary to accelerate the body. We also measured the change in joint moment and angular excursion with acceleration to determine whether the mechanism for increasing work output at a joint involved an increase in muscle force or muscle shortening. The increase in joint work at the hip and ankle resulted almost entirely from an increase in joint angular excursion during stance. Hip extension increased by more than threefold from the lowest to the highest accelerations, and the angular excursion of the ankle increased from -24.8+/-4.7 degrees (net flexion) at the lowest accelerations to 33.0+/-12.8 degrees (net extension) at the highest accelerations. Mean stance joint moment was unchanged with acceleration at the ankle and increased by approximately 35% at the hip across the range of accelerations. These patterns of joint moment and excursion indicate that turkeys increase mechanical work for acceleration primarily by increasing muscle shortening, rather than muscle force.

Acceleration↗
PubMed1999

Short-arm (1.9 m) +2.2 Gz acceleration: isotonic exercise load-O2 uptake relationship.

BACKGROUND: The deconditioning syndrome from prolonged bed rest (BR) or spaceflight includes decreases in maximal oxygen uptake (VO2max), muscular strength and endurance, and orthostatic tolerance. In addition to exercise training as a countermeasure, +Gz (head-to-foot) acceleration training on 1.8-2.0 m centrifuges can ameliorate the orthostatic and acceleration intolerances induced by BR and immersion deconditioning. PURPOSE: Study A was designed to determine the magnitude and linearity of the heart rate (HR) response to human-powered centrifuge (HPC) acceleration with supine exercise vs. passive (no exercise) acceleration. Study B was designed to test the hypothesis that moderate +Gz acceleration during exercise will not affect the respective normal linear relationships between exercise load and VO2max, HR, and pulmonary ventilation (VEBTPS). Study C: To determine if these physiological responses from the HPC runs (exercise + on-platform acceleration) will be similar to those from the exercise + off-platform acceleration responses. METHODS: In Study A, four men and two women (31-62 yr) were tested supine during exercise + acceleration and only passive acceleration at 100% [maximal acceleration (rpm) = Amax] and at 25%, 50%, and 75% of Amax. In Studies B and C, seven men (33+/-SD 7 yr) exercised supine on the HPC that has two opposing on-platform exercise stations. A VO2max test and submaximal exercise runs occurred under three conditions: (EX) exercise (on-platform cycle at 42%, 61%, 89% and 100% VO2max) with no acceleration; (HPC) exercise + acceleration via the chain drive at 25%,50%, and 100% Gzmax (35%, 72% and 100% VO2max); and (EXA) exercise (on-platform cycle at 42%, 61%, 89%, and 100% VO2max) with acceleration performed via the off-platform cycle operator at +2.2+/-0.2 Gz [50% of max (rpm) G]. RESULTS: Study A: Mean (+/-SE) Amax was 43.7+/-1.3 rpm (mean = +3.9+/-0.2, range = 3.3 to 4.9 Gz). Amax run time for exercise +acceleration was 50-70 s, and 40-70 s for passive acceleration. Regression of X HR on Gz levels indicated explained variances (r2) of 0.88 (exercise) and 0.96 (passive). The mean exercise HR of 107+/-4 (25%), to 189+/-13 (100%) bpm were 43-50 bpm higher (p < 0.05) than comparable passive HR of 64+/-2 to 142+/-22 bpm, respectively. Study B: There were no significant differences in VO2, HR or VEBTPS at the submaximal or maximal levels between the EX and EXA runs. Mean (+/-SE) VO2max for EX was 2.86+/-0.12 L x min(-1)(35+/-2 ml x min(-1) x kg(-1)) and for EXA was 3.09+/-0.14 L x min(-1) (37+/-2 ml-min(-1) x kg(-1)). Study C: There were no significant differences in the essentially linear relationships between the HPC and EXA data for VO2 (p = 0.45), HR (p < 0.08), VEBTPS (p = 0.28), or the RE (p = 0.15) when the exercise load was % VO2max. CONCLUSION: Addition of + 2.2 Gz acceleration does not significantly influence levels of oxygen uptake, heart rate, or pulmonary ventilation during submaximal or maximal cycle ergometer leg exercise on a short-arm centrifuge.

Acceleration↗