Nine bovine muscles (m. adductor, m. gluteobiceps, m. gluteus medius, m. longissimus lumborum, m. longissimus thoracis, m. psoas major, m. semimembranosus, m. supraspinatus and m. semitendinosus) were removed from beef carcasses (n = 18) to study the affects of muscle, grade, and display time on color stability. Carcasses represented two USDA quality grades (Choice and Select) equally. Muscles were cut into steaks at 10 d postmortem and displayed under retail conditions for 7 d. Percent fat had a muscle × grade interaction as muscle reacted differently based on grade. The m. gluteobiceps, m. gluteus medius, and m. semitendinosus from Choice carcasses tended to be higher in percent fat than those from Select carcasses. Percent metmyoglobin increased from d 1 to d 7. High color stable muscles (e.g., m. longissimus lumborum and m. longissimus thoracis) displayed the least percent metmyoglobin. Generally most muscles displayed high metmyoglobin reductase activity throughout retail display. Aerobic reducing ability for low color stability muscles were high on d 1 and decreased dramatically by d 7, whereas high color stability muscles (m. longissimus lumborum and m. longissimus thoracis) showed an increase in aerobic reducing ability before decreasing on d 7. Oxygen penetration depth was highest over the retail display in the two most color stable muscles (m. longissimus lumborum and m. longissimus thoracis). Myoglobin content decreased over time for all muscles despite differences in initial myoglobin concentration between muscles. TBARS values generally were a good indicator of discoloration and lean color. Color panel found that low color stability muscles decreased rapidly in lean color and increased in discoloration. Those muscles with poor color stability tended to have lower Hunter L* (lightness) and a* (redness). Muscle clearly had a major impact on overall color stability; however, grade showed only few differences, which conflicted with results from previous research. The USDA Select steaks tended to be higher in color stability than USDA Choice. Data indicated that differences in muscle types and grades play a major role in shelf-stability due to different oxidative potentials and reducing ability, and remain complicated factors in the quest to better understand color stability.

No description available.

Nineteen bovine muscles were removed from beef carcasses (n = 9). Muscles were trimmed free of fat, cut into 2.54 cm thick steaks, and were packaged in Styrofoam trays with polyvinylchloride overwrap. Steaks were assigned randomly to a day of retail display (0-, 1-, 2-, 3-, 4-, or 5-d). Steaks were evaluated over the course of retail display for objective measures of discoloration (metmyoglobin, oxymyoglobin, L*-, a*-, and b*-values), reducing ability (metmyoglobin reductase activity, resistance to induced metmyoglobin formation, and nitric oxide metmyoglobin reducing ability), oxygen consumption rate, oxygen penetration depth, myoglobin content, oxidative rancidity, and pH. Muscles were grouped according to objective color measures of discoloration. M. longissimus lumborum, M. longissimus thoracis, M. semitendinosus, and M. tensor fasciae latae were grouped as "high" color stability muscles, M. semimembranosus, M. rectus femoris, and M. vastus lateralis were grouped as "moderate" color stability muscles, M. trapezius, M. gluteus medius, and M. latissimus dorsi were grouped as "intermediate" color stability muscles, M. triceps brachi - long head, M. biceps femoris, M. pectoralis profundus, M. adductor, M. triceps brachi - lateral head, and M. serratus ventralis were grouped as "low" color stability muscles, and M. supraspinatus, M. infraspinatus, and M. psoas major were grouped as "very low" color stability muscles. Generally, muscles of high color stability had high resistance to induced metmyoglobin formation, nitric oxide reducing ability, and oxygen penetration depth and possessed low oxygen consumption rates, myoglobin content, and oxidative rancidity. In contrast, muscles of low color stability had high metmyoglobin reductase activity, oxygen consumption rates, myoglobin content, and oxidative rancidity and low resistance to induced metmyoglobin formation, nitric oxide metmyoglobin reducing ability, and oxygen penetration depth. Data indicate that discoloration differences between muscles are related to the amount of reducing activity relative to the oxygen consumption rate.

Questionnaires were constructed to measure dieter's beliefs in their abilities to (1) adhere to a diet in eating situations, (2) perform various dieting behaviors, and (3) reach their dieting goals. The three questionnaires were called the Situation-, Behavior-, and Goal-Based Dieting Self-Efficacy Scales. / Preliminary work examined the reliability of the three scales. The Situtation-Based scale demonstrated a high level of test-retest reliability over a two to four week period in the two college samples. Examination of scale intercorrelations in the clinical sample indicated that the scales were correlated at only a low level, suggesting that the scales measure different aspects of the construct of dieting self-efficacy. / Results of the laboratory studies demonstrated that the Situation-Based scale was a significant predictor of how much dieters ate in response to two different types of challenges to their diets, high calorie preloads and a depressed mood induction. / The ability of the three scales to predict weight changes was examined in the clinical sample. Only the Goal-Based scale was found to predict weight change. / In summary, the present study adds to the body of literature supporting goal-based dieting self-efficacy as a significant predictor of weight change during dieting attempts. Suggestions were offered about ways to apply this finding to clinical practice, in the areas of patient selection and treatment prescription. / The present research was limited in the following ways. The laboratory studies were limited by the narrow range of subjects, and the artificiality of the eating situation. Future research should extend this finding with other populations, as well as methodologies for examining the relation between dieting self-efficacy and eating in real-life situations. The clinical study was limited by the absence of a follow-up assessment. Future research must examine the ability of dieting self-efficacy to predict weight change over longer periods of time. Finally, suggestions were made concerning the importance of future research attempting to clarify the construct of dieting self-efficacy, particularly research aimed at determining the relation between responses to these questionnaires and the actual cognitive processes engaged in by dieters in eating situations, and over the course of their weight control efforts. (Abstract shortened with permission of author.)

Our first objective was to compare deuterium incorporation and mass isotopomer distribution analysis in the measurement of in vivo cholesterol biosynthesis in humans. Twelve healthy subjects were recruited to participate in a 24 h stable isotope infusion study which mimicked temporal conditions typical of both deuterium incorporation and mass isotopomer distribution analysis techniques. Data suggest both deuterium incorporation and mass isotopomer distribution analysis accurately define cholesterol synthesis in humans when measured over a period of 24 h. / Our second objective was to examine the effects of weight loss through energy restriction upon human in vivo circulating cholesterol concentrations and synthesis using the deuterium incorporation methodology. Seven overweight subjects with a mean BMI of 30.6 +/- 1.6 kg·m-2 were recruited into a 2-phase prospective clinical trial including 3 mo on a weight stable American Heart Association Step I diet and 6 mo on an energy-reduced American Heart Association Step I diet. Data suggest that deuterium incorporation and mass isotopomer distribution analysis are equally effective methods for measuring cholesterol biosynthesis in humans, and that energy restriction resulting in modest weight loss effectively reduces endogenous cholesterol synthesis thus decreasing the risk of CVD development in obese and overweight men. (Abstract shortened by UMI.)

The sulphate-reducing bacteria (SRB) are a diverse group of organisms which use sulphate as a terminal electron acceptor and produce the highly toxic gas, hydrogen sulphide. The deleterious effects of this include hydrocarbon reservoir souring, formation damage and microbial corrosion. The SRB are of major economic importance to the oil industry. However, knowledge of the microbial ecology of the deep subsurface remains limited. The aim of this project was to investigate whether organisms are indigenous to the hydrocarbon formation and/or are introduced during drilling operations. A range of molecular techniques such as 16S rDNA sequence analysis, probing with labelled oligonucleotides, and denaturing gradient gel electrophoresis (DGGE) were employed to investigate the microbial diversity in oil field samples. A wide range of bacterial 16S rDNA sequences were identified using these molecular methods. An analysis of drilling mud samples revealed a diverse range of bacterial 16S rDNA sequences confirming that bacteria, including SRB, can be introduced to the reservoir during drilling operations. A number of bacterial 16S rDNA sequences were recovered from a geological core sample taken from a depth of 9,770 feet. The microbial diversity was remarkable in such a high temperature, high pressure environment. This lends credence to the theory that certain bacteria may be indigenous to the subsurface environment. Scanning electron micrographs of core which had been incubated in growth medium indicated the presence of 'nannobacteria'. These tiny coccoids, with a diameter of only 0.1 μm are far smaller than the generally accepted minimum size for cellular life forms. The nannobacteria grew in regular colony shaped structures and were seen only in sections taken from inside the rock. This study indicates that hydrocarbon reservoirs provide an environment in which bacteria, if introduced during drill operations, may become established. However, the subsurface also contains complex indigenous microbial populations that demonstrate considerable species diversity and may include unrecognised life forms.

The purpose of this study was to determine effects of diet composition and exercise on the loss and maintenance of loss of body weight and body fat; and the protection of muscle in obese subjects. Ten subjects who were members of the Ball State University (BSU) Adult Fitness Program and/or the BSU Weight Management Program, and who were at least 120 percent of ideal body weight, participated in the one-year study.Three-day diet records collected at four-month intervals were assessed using the Nutriplanner computer data base to determine energy and nutrient composition of subjects' diets. Measures of weight, triceps skinfolds (TSF), and arm circumference were collected at three-month intervals to assess changes in weight, arm fat area (AFA), and arm muscle area (AMA). Adherence to exercise was reported by participants.The findings of this study showed that obese subjects who consumed low-fat, high-carbohydrate diets while adhering to an exercise program lost, or tended to lose, more weight and arm fat area, while experiencing an increase in arm muscle area. Further studies in this area of research are needed to assess the effects of diet composition, exclusive of exercise, on changes in fat and muscle area. In addition, work is needed to develop more reliable means of assessing food intake over an extended period of time.

Twelve highly trained collegiate wrestlers were studied to determine if performance of a six-minute arm crank task can be maintained by feeding a hypocaloric, high percentage carbohydrate diet to athletes during a four day weight loss period. Subjects were placed on a hypocaloric, low percentage (41.9%) carbohydrate diet (LC) and a hypocaloric, high percentage (65.9%) carbohydrate diet (HC) during two separate weight loss periods. The reduction in work performed during six minutes of arm cranking from pre- to post-weight loss was 0.9% and 8.2% for HC and LC treatments, respectively. Post exercise lactate measures were significantly lower and pH values were significantly higher pre- and post-weight loss under the LC treatment as compared to the HC treatment. Pre-exercise glycerol values were significantly higher post weight loss as compared to pre weight loss under both diet treatments. Profile of Mood State (POMS) scores indicate a negative effect of weight loss on psychological well being of the subjects. This negative effect is exacerbated during weight loss under the LC as compared to HC treatment. These data indicate a significant reduction in performance following a four day weight loss of 6.1% under the LC treatment, while performance is maintained following the HC treatment. / Department of Biology

No description available.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 66-70). Also available via the Internet.