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Biomedical subjects

A H Brown

Publications and source records attributed to A H Brown.

At least 19 recordsLinked to original sources
PubMed1992

Is repeated coronary surgery for recurrent angina cost effective?

Between January 1980 and May 1988, 1363 patients underwent first time coronary artery bypass grafting (CABG) and 49 (3.6%) were reoperated for recurrent angina by the same surgeon in this unit. There were 42 males and five females with a mean age of 53.6 years. Mean time since first operation was 68.9 (37 SD) months. Prior to surgery only eight (16.3%) were still working. There were three hospital deaths and two late deaths at 2.5 and 3.5 years after surgery and one patient underwent cardiac transplantation at 1.5 years. Follow-up has been completed up to March 1989, mean 3.7 years, range 10-108 months. Questionnaires were sent to all patients concerning the financial and functional situation. Hospital expenses were calculated (a) prospectively for 15 consecutive first time CABGs and for five second time CABGs, (b) retrospectively from patients' records with the help of a simple computer programme. The final figures were corrected for inflation rates. The 1- and 5-year actuarial probability of angina-free interval was 87.5% and 40% respectively. Eight patients (12.2%) had no benefit, six (13.6%) had benefit but were not able to work, 16 (36.4%) were able to work but unemployed and 14 (13.8%) were fully employed producing a total salary of 69,072 pounds per annum. Hospital expenses were: first time CABG 3645-4049 pounds, second time CABG 6290-7235. The total for the entire group was 308 166 pounds. Repeated coronary surgery can be accomplished with reasonable mortality and has good late results.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1992

Effect of including relationships in the estimation of genetic parameters of beef calves.

Variances and covariances for birth weight, gain from birth to weaning (ADG), and 205-d weight were obtained from a sire-dam model and a sire-maternal grandsire model for a herd of Angus and a herd of Hereford cattle. Estimates of direct additive genetic variance (sigma 2A), maternal additive genetic variance (sigma 2M), covariance between direct and maternal additive genetic effects (sigma AM), permanent environmental variance (sigma 2PE), and residual variance (sigma 2e) were obtained both with and without the inverse of the numerator relationship matrix (A-1) included. Estimates of heritability for direct genetic effects (h2A), maternal genetic effects (h2M), and the correlation between direct and maternal effects (rAM) for birth weight were .37, .18, and -.01 in Angus and .53, .23, and -.19 in Herefords, respectively, for the analyses without A-1. For the analyses with A-1, estimates of h2A, h2M, and rAM were .42, .22, and -.12 for Angus and .58, .22, and -.13 for Herefords, respectively. Estimates of h2A, h2M, and rAM for ADG were .43, .15, and -.44 in Angus and .52, .38, and -.03 in Herefords, respectively, without A-1. With A-1, estimates of h2A, h2M, and rAM were .57, .15, and -.32 for Angus and .58, .39, and -.05 for Herefords, respectively. Estimates of h2A, h2M, and rAM for 205-d weight were .49, .15, and -.46 for Angus and .58, .43, and -.06 for Herefords, respectively, without A-1. With A-1, estimates of h2A, h2M, and rAM were .63, .16, and -.36 for Angus and .66, .43, and -.08 for Herefords, respectively. Estimates of h2A were higher with A-1 than without A-1, but estimates of h2M were similar. Using variances and covariances obtained from analyses including A-1 generally gave higher estimates of direct breeding values than using variances and covariances obtained from analyses not including A-1. Both Pearson product-moment and Spearman rank correlations were high (.99) between estimates of breeding values from the two analyses, although some changes in rank did occur.

Analysis of Variance↗
PubMed1992

Estimates of repeatability and heritability of horn fly resistance in beef cattle.

Horn fly population density on 215 beef cows representing seven breed groups and 51 sires was used to obtain estimates of repeatability (rXX) and heritability (h2) for resistance to the horn fly (Haematobia irritans [L.] Diptera: Muscidae). Total horn fly densities were determined weekly on each cow beginning in May and ending in late October or early November of 1988, 1989, and 1990. No insecticides were used on cattle in this study. Estimates of h2 for horn fly resistance (low horn fly number per cow) were obtained by the paternal half-sib method (4 sigma 2S) and as twice the intrasire regression of offspring on dam (2bDD/S). Variance component estimates were obtained using a completely nested ANOVA that included overall mean, breed, sire/breed, cow/sire, and residual error. One hundred twenty-six daughter-dam pairs were available for regression analysis. In a preliminary analysis, the within-breed regression was nonsignificant (P greater than .05), implying that the regression was the same for all breeds; therefore, breed was deleted from the model. The regression model included an overall mean, year, and the intrasire regression of daughter on dam (bDD/S). The estimate of rXX was .47 +/- .02. Estimates of h2 were .78 +/- .16 and .59 +/- .10 from the 4 sigma 2S and 2bDD/S methods, respectively. Similar estimates of rXX and h2 were obtained when each observation of horn fly number per cow (x) was transformed to both log10 (x) and square root of x. These estimates suggest the possibility of selection procedures as an environmentally safe alternative to the use of chemical control.

Analysis of Variance↗
PubMed1991

Interactive response of the horn fly (Diptera: Muscidae) and selected breeds of beef cattle.

Statistically significant differences were observed in the population density of the horn fly, Haematobia irritans irritans (L.), on different breeds of beef cattle. The European breed Chianina had a population density of horn flies generally less than or equal to 50% than that of the British cattle breeds (Angus, Hereford, Polled Hereford, and Red Poll) and another European breed (Charolais). Generally, no significant difference existed among numbers of horn flies on Hereford, Polled Hereford, and Red Poll cows in 1988 or among Angus, Hereford, Polled Hereford, and Red Poll cows in 1989. Factors other than color appeared to be involved in the selective process between the horn fly and its host. Population densities on two white European breeds (Charolais and Chianina) were significantly different on all weekly intervals except for 4 wk in both 1988 and 1989. No significant difference existed among Charolais and British breeds except during 4 wk in 1988 and 3 wk in 1989. When weaning weights of all calves were adjusted for the effects of age to 205 d, sex of calf, and age of dam, the indirect effect of the horn fly on weaning weight showed a significant linear regression. Each 100 flies per cow caused a reduction of 8.1 kg in calf weaning weight. Cows within each breed with low numbers of horn flies weaned significantly heavier calves than cows with higher numbers of horn flies.

Animals↗
PubMed1991

Effects of 84-, 112- and 140-day postweaning feedlot performance tests for beef bulls.

Changes in performance traits in beef cattle over the last 30 yr necessitate the re-evaluation of central testing procedures to ensure that they are cost effective and appropriate for current test objectives. The objective of this study was to evaluate the potential for reducing the length of evaluation from 140 d to either 112 or 84 d. Data evaluated were postweaning feedlot performance test records (collected from 1977 to 1986) on 1,830 individually fed bulls. Bulls representing 13 breeds (n greater than 25 per breed) were evaluated in the University of Arkansas Cooperative Bull Tests at Fayetteville, Hope, and Monticello, Arkansas. Models were fit for ADG, daily feed intake (FI) and feed conversion (FCONV) from d 1 to d 140 (ADG1-140, FI1-140 and FCONV1-140, respectively) and from d 1 to d 112 (ADG1-112, F11-112 and FCONV1-112, respectively). Models fit for ADG1-140, FI1-140, and FCONV1-140 using information up to d 112 had R2 of .90, .99, .88, and .94, respectively, and using information up to d 84 had R2 of .82, .94, and .80, respectively. Spearman rank correlation coefficients (all P less than .0001) were .93 for ADG1-140 and ADG1-112, .93 for ADG1-112 and ADG1-84, .99 for FI1-140 and FI1-112, .91 for FCONV1-140 and FCONV1-112, and .90 for FCONV1-112 and FCONV1-84. These coefficients indicate that bulls ranked similarly for performance traits at 84, 112, and 140 d. If the primary objective of central station testing is to evaluate ADG during the linear phase of growth, and if testing procedures are those currently recommended by the Beef Improvement Federation, then feeding bulls beyond 112 d has no advantage because the information upon which selection decisions are made is similar at both 112 and 140 d.

Analysis of Variance↗
PubMed1991

Dissection of the two internal mammary arteries with maximal exposure and minimal adverse sequelae by means of an inexpensive, simple, atraumatic retractor.

The increasing use of internal mammary arteries for grafting, the possibility that both internal mammary arteries should be used, and the need for longer portions of these vessels should multiple sequential distal anastomoses be needed make a technique for safe and extensive dissection of these vessels important. We describe such a technique that uses a retractor adapter. This adaptation has considerably reduced our reluctance to use both mammary arteries and to dissect lengths that can be used for multiple distal anastomoses. It has also reduced the prevalence of undesirable side effects from retraction.

Dissection↗
PubMed1990

Breed means for average daily gain, feed conversion and intake of beef bulls during postweaning feedlot performance tests.

Comparisons of ADG, feed/gain, daily feed intake and daily feed intake as percentage of body weight may be important to beef cattle producers and researchers in breed selection and computer modeling. Data evaluated were postweaning feedlot performance test records collected from 1967 to 1986 of 3,661 individually fed bulls. Bulls originated from University of Arkansas purebred herds, Fayetteville, and the University of Arkansas Cooperative Bull Tests at Fayetteville, Hope and Monticello. Data were analyzed separately for years 1967 to 1976 (P1) (n = 1,654) and 1977 to 1986 (P2) (n = 2,007). Breeds in P1 were Hereford (HH), Angus (AN), Charolais (CH), Polled Hereford (HP) and Santa Gertrudis (SG). Breeds in P2 were HH, AN, CH, HP, SG, Simmental (SM), Maine-Anjou (MA), Brangus (BN) and Beefmaster (BM). The model fitted included initial age, breed and test number (all P less than .01 except for initial age on ADG in P1). Test number included variation of year, location and season. Breed rankings from highest to lowest for ADG in P1 were CH, SG, HH, HP and AN and in P2 were MA, CH, SM, AN, HP, SG, HH, BN and BM. Breed rankings from highest to lowest for feed/gain in P1 were AN, SG, CH, HP and HH and in P2 were BM, BN, AN, SG, HP, SM, HH, MA and CH. Breeds highest to lowest for daily feed intake (as-fed basis) in P1 were CH, SG, AN, HP and HH and in P2 were SM, MA, CH, AN, BN, HP, SG, HH and BM.(ABSTRACT TRUNCATED AT 250 WORDS)

Analysis of Variance↗
PubMed1989

Aspartate aminotransferase isozymes in the genus Capsella (Brassicaceae): subcellular location, gene duplication, and polymorphism.

The subcellular location of aspartate aminotransferase isozymes (EC 2.6.1.1) in the genus Capsella (Brassicaceae) was studied. The diploid species C. grandiflora and C. rubella have three AAT isozymes, including one located in the plastids. Each locus is duplicated in the tetraploid Capsella bursa-pastoris. Variation at the plastid-coding locus exceeded that at the other loci. C. bursa-pastoris had some unique alleles not detected in the diploid species. Segregation in open-pollinated families revealed that Capsella grandiflora was outcrossing, whereas C. rubella was highly inbred, with most populations homozygous or uniform at all three loci. Inheritance in the tetraploid colonizer C. bursa-pastoris is disomic. This species was also predominantly selfing with outcrossing rates between 2% and 10%.

Alleles↗
PubMed1988

Reperfusion with nifedipine: improved functional recovery after cold cardioplegic arrest.

Nifedipine, an antagonist of myocardial calcium uptake, given after a period of a cold, cardioplegic arrest (150 min, 18 degrees C, St Thomas' cardioplegic solution) improved contractile recovery of the isolated working rat heart model of cardiopulmonary bypass. The hearts were reperfused with various concentrations of nifedipine in Krebs-Henseleit buffer (37 degrees C, 100 cm H2O) and their functional recoveries were compared with the control series reperfused without nifedipine. A bell-shaped dose/response curve was produced by the drug, and optimal protection observed with 0.1 mumol/l of nifedipine which improved the post-ischaemic recovery of the aortic flow from 56.8% +/- 3.7% to 80.1% +/- 3.2% (P less than 0.001). The importance of careful dose adjustment is stressed since it was noted that higher concentrations inhibit both functional and metabolic performance. This study supports the hypothesis that at the end of a cold cardioplegic arrest there are still reversibly injured cells which could restore their function if the cellular ingress of Ca++ during reperfusion is reduced by nifedipine.

Animals↗
PubMed1988

Relationships among absolute growth rate, relative growth rate and feed conversion during postweaning feedlot performance tests.

Knowledge of the relationships between absolute growth rate (AGR), relative growth rate (RGR) and feed conversion (FCONV) of bulls in postweaning feedlot performance tests can give cattle producers important information for selecting superior sires. Weight gain and FCONV data that were collected during 16 yr were analyzed from 393 Angus and 340 Hereford bulls by 26 and 27 sires, respectively, that were individually fed in 140-d tests. Sire variance and covariance components were used to obtain heritability (h2) estimates for AGR, RGR and FCONV and the genetic correlations (rg) and phenotypic correlations (rp) among these traits. Respective mean AGR, RGR and FCONV were 1.27 +/- .14 kg/d, .4378 +/- .0395%/d and 7.32 +/- .58 kg/kg for the Angus and 1.28 +/- .12 kg/d, .4552 +/- .0388%/d and 6.56 +/- .46 kg/kg for the Hereford bulls. Estimates of h2 were similar for AGR and RGR in both Angus (.36 +/- .11 and .22 +/- .09) and Hereford (.33 +/- .11 and .20 +/- .09) bulls. The h2 estimates for FCONV were .14 +/- .07 for Angus and .13 +/- .08 for Herefords. For the Angus and Hereford bulls, respectively, rg were .86 +/- .09 and .86 +/- .13 between AGR and RGR, -.84 +/- .38 and -.74 +/- .49 between AGR and FCONV and -.84 +/- .49 and -.61 +/- .64 between RGR and FCONV. The rp were .80 +/- .03 and .68 +/- .04 between AGR and RGR, -.58 +/- .05 and -.51 +/- .05 between AGR and FCONV and -.71 +/- .04 and -.73 +/- .04 between RGR and FCONV for the Angus and Hereford bulls, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animal Nutritional Physiological Phenomena↗
PubMed1986

Percutaneous removal of a fractured right heart catheter from the apex of the right ventricle.

A 58-year-old woman underwent right and left heart catheterization for suspected ischaemic heart disease with ventricular tachycardia. During the procedure a Bourassa catheter fractured and lodged at the right ventricular apex. Under general anaesthesia and radiographic screening the fragment was removed using a bronchoscopy biopsy forceps via the jugular vein after other methods had failed. This case highlights the need for familiarity with several techniques for the removal of such fragments.

Cardiac Catheterization↗
PubMed1986

Trends of performance in Arkansas cooperative beef-bull performance tests from 1962 through 1982.

Individual records of performance of 2787 bulls in cooperative beef-bull performance tests from 1962 through 1982 were analyzed to determine trends in final weight, average daily gain, daily feed consumption and gross feed efficiency. Data from Angus, Polled Hereford, Charolais, Hereford and Santa Gertrudis breeds were analyzed separately. Performance-test procedures and the ration fed remained the same in all tests. Least-squares means by year, adjusted for location of test, initial weight, initial age and initial condition score, were regressed on time to determine average yearly change in the traits. Yearly changes for Angus, Polled Hereford, Charolais, Hereford and Santa Gertrudis breeds in final weight were 3.3, 1.6, 3.3, 2.5, and 2.6 kg, respectively; in average daily gain and yearly changes were .02, .01, .02, .02, and .02 kg, respectively; in daily feed consumption the yearly changes were .08, .03, .09, and .04 kg, respectively; and in feed per kg gain the yearly changes were -.08, -.04, -.05, -.03, and -.07 kg, respectively. Because the test procedures were the same in all years, these trends represent genetic progress made by the Arkansas beef industry toward faster-gaining, more efficient cattle.

Animals↗
PubMed1984

Three alcohol dehydrogenase genes in wild and cultivated barley: characterization of the products of variant alleles.

Barley (Hordeum vulgare) and its wild progenitor (H. spontaneum) have three loci for alcohol dehydrogenase (EC 1.1.1.1; ADH). The Adh1 locus is constitutively expressed in seed tissues, whereas expression of the loci Adh2 and Adh3 requires anaerobic induction. The Adh3 gene is well expressed in aleurone and embryo tissues kept under N2 for 2-3 days. Using N2-treated embryos, a diverse collection of H. spontaneum was screened in starch gels for electrophoretic variants at the Adh3 locus. Four variants were found: two were conventional mobility variants (Adh3 S, Adh3 V); one was a null variant (Adh3 n); and the fourth (Adh3 I) variant lacked active homodimers and showed reduced heterodimer activity. The 35S-labeled monomers induced under N2 in the lines homozygous for Adh1, Adh2, or Adh3 variants were immunoprecipitated with antiserum raised against maize ADH. Fluorography after separation by SDS-PAGE and by urea-isoelectric focusing indicated that the Adh3 n allele was CRM- and that the Adh3 I gene product was smaller than normal. The Adh1 and Adh3 variants showed independent segregation.

Alcohol Dehydrogenase↗
PubMed1983

Three years' experience with esophageal stapling device.

The authors report their experience with forty patients undergoing resection of middle and lower thirds carcinomas of the esophagus or proximal stomach, with esophagogastric or esophagojejunal anastomosis using an end-to-end anastomosis (EEA) stapler. A fatal anastomotic leak occurred in the first two patients and seven other patients died in the early postoperative period from respiratory and cardiovascular complications. Four other patients developed fibrotic strictures between 6 and 24 months after their operation. The strictures were easily dilated and did not recur. The use of an EEA stapler is recommended because it reduces the operating time, the incidence of anastomotic leaks, and probably the blood loss. The majority of anastomoses can be accomplished exclusively through the left chest by using the stapler.

Adenocarcinoma↗