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Biomedical subjects

R V Anderson

Publications and source records attributed to R V Anderson.

At least 19 recordsLinked to original sources
PubMed2007

Carcass traits and M. longissimus lumborum palatability attributes of calf- and yearling-finished steers.

A 2-yr experiment was conducted to compare carcass characteristics and meat palatability attributes of steers ((3/4) British, (1/4) Continental) finished postweaning as calves or yearlings. Calves and yearlings of the same contemporary group were designated to a finishing system at weaning. Calves (n = 73) were finished in the feedlot (191 d) on a high-concentrate diet. Yearlings (n = 84) grazed crop residues after weaning, followed by spring and summer pasture grazing, and concluded with a short finishing period (91 d) in the feedlot. All steers were fed to a constant, fat thickness endpoint of 1 cm. The M. longissimus lumborum steaks from each production system were aged for 7, 14, or 21 d for Warner-Bratzler shear force determination and for 7 or 14 d for in-house sensory panel evaluation. Insoluble, percent soluble, and total collagen were determined. Yearlings produced heavier (P < 0.001) carcasses with larger (P < 0.001) LM areas and lower (P < 0.001) marbling scores and quality grades. Calves possessed greater amounts of total collagen (P < 0.001), with a significantly greater percentage of soluble collagen compared with yearlings (39.72 vs. 24.38%). Calves produced steaks with lower (P < 0.001) shear force values and greater (P < 0.001) sensory ratings for flavor. The USDA Choice steaks from the calves were more (P < 0.001) tender and more (P < 0.050) palatable than Choice steaks from yearlings, and USDA Select steaks from calves were rated more tender (P < 0.001), juicy (P = 0.012), and desirable (P < 0.001) than Select steaks from yearlings. As expected, increasing aging time from 7- to 14- to 21-d produced steaks with lower (P < 0.001) shear force values, regardless of the production system. Risk probabilities showed 1.24% of the steaks from calf-finished steers and 21.22% of steaks from yearling-finished steers to be tough. Sensory rating probabilities showed the steaks from the calves were most likely to be desirable for tenderness, whereas steaks from the yearlings were most likely to be undesirable for tenderness, juiciness, flavor, and overall acceptability. Thus, calf-finished steers produce carcasses superior in quality and palatability compared with those from yearling-finished steers. However, yearling-finished steers can produce tender beef with extended aging.

Aging↗
PubMed2005

An evaluation of production and economic efficiency of two beef systems from calving to slaughter.

A 3-yr experiment was conducted with cows and their calves to evaluate resource inputs, animal performance, and carcass characteristics of two production systems. In the control system, cows (CON; n = 99/yr) grazed pasture and were fed hay during the winter, and CON steer calves were finished in the feedlot for 211 d after weaning. In the treatment system (TRT; n = 100/yr), cows grazed pasture and crop residue during the winter and were fed hay. Treatment steer calves grazed crop residue after weaning, grazed pasture in the spring and summer, and were finished in the feedlot for 90 d. Body condition scores after TRT cows returned from crop residue grazing were greater (P < 0.01) for CON than for TRT cows. Calving rates were similar for both groups (CON = 91%; TRT = 93%). In the feedlot, CON steers had lower (P < 0.05) ADG and DMI, but were more efficient (P < 0.01) than TRT steers. Treatment steers had greater (P < 0.05) final weight, hot carcass weight and longissimus muscle area, and decreased marbling score. The cost per weaned calf and weaning breakeven were greater (P = 0.07) for the CON system than for the TRT system (CON = 455.12 dollars, 0.91 dollar/0.45 kg; TRT = 421.43 dollars, 0.84 dollar/0.45 kg). When steers were priced into the postweaning phase on an economic basis, slaughter breakeven was lower (P = 0.01), and profit potential tended (P = 0.14) to be greater for TRT steers when they were sold on a live basis. When steers were priced into the postweaning phase on a financial basis, slaughter breakeven was lower (P = 0.03) and profit potential from the sale of steers on a live basis was greater (P = 0.07) for TRT than for CON steers. Economic evaluation of the total system resulted in greater (P = 0.06) profit potential for the TRT system when steers were priced into the system on either an economic or a financial basis and when steers were sold on a live basis, but no differences were observed when steers were sold on a grid basis. Despite differences in cow weight and body condition, calving rates did not differ between systems. Although calves were herdmates, feedlot performance and carcass characteristics differed between systems. The TRT system had lower weaning and slaughter breakeven, lower cost per weaned calf, and greater profit potential when finished steers were sold on a live basis.

Animal Feed↗
PubMed1998

Utility of transesophageal echocardiography during port-access minimally invasive cardiac surgery.

In this study, we sought to determine the use of transesophageal echocardiography (TEE) as the primary imaging technique to assist in the placement of endovascular catheters during minimally invasive, port-access cardiac surgery. The recent development of endovascular catheters that are placed via the femoral artery and vein has enabled patients to be placed on cardiopulmonary bypass without the need for direct visualization of the heart or great vessels via sternotomy. This has allowed cardiac surgery to be performed through smaller thoracotomy incisions. Placement of these catheters has previously been performed with fluoroscopic guidance, which has major imaging limitations. Thirty-six patients underwent port-access cardiac surgery at our institution during the study period. All patients underwent intraoperative TEE. We used TEE to visualize the coronary sinus os, right atrium and superior vena cava, and thoracic aorta to assist with placement of the coronary sinus catheter, venous cannula, and endoaortic clamp. Twenty patients underwent mitral valve surgery, 14 patients coronary artery bypass grafting, 1 patient aortic valve replacement, and 1 patient repair of an atrial septal defect by the port-access approach. TEE was able to adequately visualize the cardiac structures and assist in the placement of the endovascular catheters in all patients. Fluoroscopy was only helpful as an aid to TEE for placement of the coronary sinus catheter. TEE is an excellent imaging modality for the proper placement of these new endovascular catheters, obviating the need for fluoroscopy, except to be on standby and for placement of the coronary sinus catheter.

Adult↗
PubMed1998

Pollution-tolerant allele in fingernail clams (Musculium transversum).

For nearly 50 years, the fingernail clam (Musculium transversum) was believed to be virtually eliminated from the Illinois River. In 1991, workers began finding substantial populations of M. transversum in the Illinois River including several beds in and around the highly polluted Chicago Sanitary District. In order to determine if populations of M. transversum from polluted sites exhibited any genetic response to the high levels of toxins and to examine the genetic structure of several populations of M. transversum for any changes due to the population crash, starch-gel electrophoresis was performed on M. transversum from three Illinois River localities and four Mississippi River basin locations. The sampled populations produced an inbreeding coefficient (FIS) of 0.929, indicating that the populations were highly inbred. The results of a suspected founder effect due to a bottleneck was suggested by an FST = 0.442. The isozyme Glucose-6-phosphate isomerase-2 (Gpi-2) produced allelic frequency patterns that were consistent with expected patterns of a pollution-tolerant allele. Polluted sites exhibited elevated frequencies of Gpi-2(100) whereas nonpolluted sites exhibited elevated frequencies of Gpi-2(74). This frequency pattern suggested that natural selection was occurring in populations under severe toxic pressures, leading to an increase in the frequency of the allele Gpi-2(100). Therefore, Gpi-2(100) is a possible pollution-tolerant mutation in M. transversum.

Animals↗
PubMed1998

Minimally invasive port-access coronary artery bypass grafting with early angiographic follow-up: initial clinical experience.

OBJECTIVE: New techniques for minimally invasive coronary artery bypass grafting have recently emerged. The purpose of this study was to determine the safety and efficacy of Port-Access (Heartport, Inc., Redwood City, Calif.) coronary revascularization and to evaluate with angiography the early graft patency rate with this new approach. METHODS: From October 1996 to May 1997, 31 patients underwent Port-Access coronary artery bypass grafting with an anterior minithoracotomy and endovascular-occlusion cardiopulmonary bypass. There were 26 men and 5 women with a mean age of 62 years (range 42 to 82 years). Fifteen patients underwent single bypass; 12 patients underwent double bypass, and 4 patients underwent triple bypass. Bypass conduits included the left internal thoracic artery (n = 30), right internal thoracic artery (n = 2), radial artery (n = 10), and saphenous vein (n = 6). Three sequential grafts were used. Angiographic studies of the bypass grafts were performed in 27 of 31 patients (87%). RESULTS: There were no deaths, neurologic deficits, myocardial infarctions, or aortic dissections. Conversion to sternotomy was not required in any case. There were two reoperations for bleeding, one reoperation for tamponade, and one reoperation for pulmonary embolus. Postoperative angiography revealed anastomotic patency of the left internal thoracic artery to left anterior descending artery in 26 of 26 grafts (100%) with overall anastomotic patency in 43 of 44 grafts (97.7%). CONCLUSION: These results demonstrate that Port-Access coronary artery bypass can be performed accurately and safely with acceptable morbidity. This approach allows for multivessel revascularization on an arrested, protected heart with excellent anastomotic precision and reproducible early graft patency.

Adult↗
PubMed1993

Low-flow cardiopulmonary bypass and cerebral protection: a summary of investigations.

A research program in cerebral ischemia was initiated by our laboratory to determine optimal strategies for cerebroprotection. Four studies relating to cerebroprotection using nuclear magnetic resonance spectroscopy in a sheep model of hypothermic cardiopulmonary bypass are summarized. These showed, first, that low-flow bypass, with a flow as low as 10 mL.kg-1 x min-1, maintained normal cerebral metabolism; second, that hypothermia increases the high-energy phosphate content and the intracellular pH of the brain; third, that hyperglycemia causes a profound intracellular acidosis; and, finally, that barbiturates prevent the normal increase in high-energy phosphates associated with hypothermia.

Adenosine Triphosphate↗
PubMed1992

Hyperglycemia increases cerebral intracellular acidosis during circulatory arrest.

Phosphorus 31 nuclear magnetic resonance spectroscopy was used to assess cerebral high-energy phosphate metabolism and intracellular pH in normoglycemic and hyperglycemic sheep during hypothermic circulatory arrest. Two groups of sheep (n = 8 per group) were placed in a 4.7-T magnet and cooled to 15 degrees C using cardiopulmonary bypass. Spectra were acquired before and during circulatory arrest and during reperfusion and rewarming. Intracellular pH and adenosine triphosphate levels decreased during circulatory arrest. Compared with the normoglycemic animals, the hyperglycemic group was significantly more acidotic with the greatest difference observed during the first 20 minutes of reperfusion (6.40 +/- 0.08 versus 6.08 +/- 0.06; p < 0.001). Intracellular pH returned to baseline after 30 minutes of reperfusion in the normoglycemic group but did not reach baseline until 1 hour of reperfusion in the hyperglycemic animals. Adenosine triphosphate levels were significantly higher in the hyperglycemic group during circulatory arrest. Repletion of adenosine triphosphate during reperfusion was similar for both groups. These results support the hypothesis that hyperglycemia during cerebral ischemia drives anaerobic glycolysis and thus leads to increased lactate production and an increase [corrected] in the intracellular acidosis normally associated with ischemia.

Acidosis, Lactic↗
PubMed1992

Barbiturates impair cerebral metabolism during hypothermic circulatory arrest.

Barbiturates have been used as a method of cerebral protection in patients undergoing open heart operations. Phosphorus 31 nuclear magnetic resonance spectroscopy was used to assess barbiturate-induced alterations in the cerebral tissue energy state during cardiopulmonary bypass, hypothermic circulatory arrest, and subsequent reperfusion. Sheep were positioned in a 4.7-T magnet with a radiofrequency coil over the skull. Nuclear magnetic resonance spectra were obtained at 37 degrees C, during cardiopulmonary bypass before and after drug administration at 37 degrees C and 15 degrees C, throughout a 1-hour period of hypothermic circulatory arrest, and during a 2-hour reperfusion period. A group of animals (n = 8) was administered a bolus of sodium thiopental (40 mg/kg) during bypass at 37 degrees C followed by an infusion of 3.3 mg.kg-1 x min-1 until hypothermic arrest. A control group of animals (n = 8) received no barbiturate. The phosphocreatine/adenosine triphosphate ratio, reflecting tissue energy state, was lower during cardiopulmonary bypass at 15 degrees C in the treated animals compared with controls (1.06 +/- 0.08 versus 1.36 +/- 0.17; p < 0.001). Lower phosphocreatine/adenosine triphosphate ratios were observed throughout all periods of arrest and reperfusion in the barbiturate-treated animals compared with controls (p < or = 0.01). Thiopental prevented the increase in cerebral energy state normally observed with hypothermia and resulted in a decrease in the energy state of the brain during hypothermic circulatory arrest and subsequent reperfusion. These results suggest that thiopental administration before a period of hypothermic circulatory arrest may prove detrimental to the preservation of the energy state of the brain.

Adenosine Triphosphate↗
PubMed1985

Inhibition of the differentiation of Candida albicans by the chelator 1,10-phenanthroline.

Several chelators were examined for their ability to prevent the synchronous release of 24- to 48-hour stationary phase singlet cells of the dimorphic yeast Candida albicans into either the mycelial or the budding phenotypes (in a defined liquid medium at 37 degrees C; at pH 6.5 or pH 4.5, respectively). The only chelator that was found to inhibit mycelium formation completely and to restrict bud formation to about 10% was 1,10-phenanthroline at minimal concentrations of 50 microM and 230 microM, respectively. The inhibition of both phenotypes could be reversed completely by the addition of 200 microM of ZnSO4. The synchrony of recovery from inhibition by the addition of zinc paralleled that of the controls for both phenotypes, and the final number of mycelia or buds as a percentage of the control was the same (100%). These findings support the hypothesis that the lag period between the release from stationary phase and the onset of development for Candida represents the time of acquisition of a minimum threshold amount of a cation, such as zinc. The involvement of zinc in phenotypic development is discussed, suggesting that while zinc is involved in the initiation of development, it may not determine the phenotype of Candida albicans.

Candida albicans↗