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Biomedical subjects

D J Johnston

Publications and source records attributed to D J Johnston.

14 recordsLinked to original sources
PubMed2005

The influence of lower face vertical proportion on facial attractiveness.

This study investigated the influence of changing lower face vertical proportion on the attractiveness ratings scored by lay people.Ninety-two social science students rated the attractiveness of a series of silhouettes with normal, reduced or increased lower face proportions. The random sequences of 10 images included an image with the Eastman normal lower face height relative to total face height [lower anterior face height/total anterior face height (LAFH/TAFH) of 55 per cent], and images with LAFH/TAFH increased or decreased by up to four standard deviations (SD) from the Eastman norm. All the images had a skeletal Class I antero-posterior (AP) relationship. A duplicate image in each sequence assessed repeatability. The participants scored each image using a 10 point numerical scale and also indicated whether they would seek treatment if the image was their own profile. The profile image with normal vertical facial proportions was rated by the lay people as the most attractive. Attractiveness scores reduced as the vertical facial proportions diverged from the normal value. Images with a reduced lower face proportion were rated as significantly more attractive than the corresponding images with an increased lower face proportion. Images with a reduced lower face proportion were also significantly less likely to be judged as needing treatment than the corresponding images with an increased lower face proportion.

Adolescent↗
PubMed2003

Are facial expressions reproducible?

OBJECTIVES: To determine the extent of reproducibility of five facial expressions. DESIGN: Thirty healthy Caucasian volunteers (15 males, 15 females) aged 21 to 30 years had 20 landmarks highlighted on the face with a fine eyeliner pencil. Subjects were asked to perform a sequence of five facial expressions that were captured by a three-dimensional camera system. Each expression was repeated after 15 minutes to investigate intrasession expression reproducibility. To investigate intersession expression reproducibility, each subject returned 2 weeks after the first session. A single operator identified 3-dimensional coordinate values of each landmark. A partial ordinary procrustes analysis was used to adjust for differences in head posture between similar expressions. Statistical analysis was undertaken using analysis of variance (linear mixed effects model). RESULTS: Intrasession expression reproducibility was least between cheek puffs (1.12 mm) and greatest between rest positions (0.74 mm). The reproducibility of individual landmarks was expression specific. Except for the lip purse, the reproducibility of facial expressions was not statistically different within each of the two sessions. Rest position was most reproducible, followed by lip purse, maximal smile, natural smile, and cheek puff. Subjects did not perform expressions with the same degree of symmetry on each occasion. Female subjects demonstrated significantly better reproducibility with regard to the maximal smile than males (p =.036). CONCLUSIONS: Under standardized conditions, intrasession expression reproducibility was high. Variation in expression reproducibility between sessions was minimal. The extent of reproducibility is expression specific. Differences in expression reproducibility exist between males and females.

Adult↗
PubMed2002

Purebred-crossbred performance and genetic evaluation of postweaning growth and carcass traits in Bos indicus x Bos taurus crosses in Australia.

Growth and carcass data on 7,154 cattle from a purebred project and 1,241 cattle from a crossbred project, comprising 916 first-crosses and 325 purebred Brahman controls, were analyzed to estimate genetic parameters, including the genetic correlations between purebred and crossbred performance (rpc). The data also allowed the estimation of sire breed means for various growth and carcass traits. Crossbred calves were produced using 9 Angus, 8 Hereford, 7 Shorthorn, 14 Belmont Red, and 8 Santa Gertrudis sires bred to Brahman dams. These same sires produced 1,568 progeny in a separate purebreeding project. Cattle in both projects were managed under two finishing regimens (pasture and feedlot) to representative market live weights of 400 (domestic), 520 (Korean), and 600 kg (Japanese). The traits studied included live weight at around 400 d of age (400W), hot carcass weight (CWT), retail beef yield percentage (RBY), intramuscular fat percentage (IMF), rump fat depth (P8), and preslaughter ultrasound scanned eye muscle area (SEMA). Estimated breeding values (EBV) of sires from their BREEDPLAN genetic evaluations were used to assess their value in predicting crossbred performance. Regressions of actual crossbred calf performance on sire EBV for each of the traits differed little from their expectation of 0.5. Angus sires produced crossbred carcasses with the highest P8 and lowest RBY but highest IMF. In contrast, crossbred progeny from Belmont Red sires had the lightest 400W and CWT, lowest P8, and highest RBY. Estimates of rpc were 0.48, 0.48, 0.83, 0.95, 1.00, and 0.78 for 400W, CWT, RBY, IMF, P8, and SEMA, respectively. Commercial breeders selecting sires for crossbreeding programs with Brahman females, based on EBV computed from purebred data, might encounter some reranking of sire's performance for weight-related traits, with little expected change in carcass traits.

Adipose Tissue↗
PubMed2001

Comparison of radiographic image quality from four digitization devices as viewed on computer monitors.

The objective of this study was to compare the quality of radiographic images digitized from commercial-grade and consumer-grade digital cameras and scanners as viewed on computer monitor. Radiographic images were digitized from hardcopy film using a commercial-grade laser scanner, a consumer-grade desktop flatbed scanner, a commercial-grade digital camera, and a consumer-grade digital camera. The quality of images without and with grayscale histogram adjustment was evaluated subjectively by 10 board-certified radiologists. Optical density response was evaluated objectively using a grayscale test pattern. There was no significant difference in subjective quality among images digitized with the commercial scanner, consumer scanner, and commercial camera. The quality of images digitized with the consumer camera was lower than the other 3. Objective tests showed the commercial scanner to have the most linear optical density response. For the purpose of viewing images on a computer monitor, a consumer-grade desktop scanner can produce images of similar quality to those produced by more expensive laser commercial-grade scanners and digital cameras and provides cost-efficient means to digitize radiographic plain films. A consumer-grade camera may not be optimal for use in this setting.

Analysis of Variance↗
PubMed2001

Genetic and phenotypic variance and covariance components for feed intake, feed efficiency, and other postweaning traits in Angus cattle.

Records on 1,180 young Angus bulls and heifers involved in performance tests were used to estimate genetic and phenotypic parameters for feed intake, feed efficiency, and other postweaning traits. The mean age was 268 d at the start of the performance test, which comprised 21-d adjustment and 70-d test periods. Traits studied included 200-d weight, 400-d weight, scrotal circumference, ultrasonic measurements of rib and rump fat depths and longissimus muscle area, ADG, metabolic weight, daily feed intake, feed conversion ratio, and residual feed intake. For all traits except the last five, additional data from the Angus Society ofAustralia pedigree and performance database were included, which increased the number of animals to 27,229. Genetic (co)variances were estimated by REML using animal models. Direct heritability estimates for 200-d weight, 400-d weight, rib fat depth, ADG, feed conversion,and residual feed intake were 0.17 +/- 0.03, 0.27 +/- 0.03, 0.35 +/- 0.04, 0.28 +/- 0.04, 0.29 +/- 0.04, and 0.39 +/- 0.03, respectively. Feed conversion ratio was genetically (r(g) = 0.66 ) and phenotypically (r(p) = 0.53) correlated with residual feed intake. Feed conversion ratio was correlated (r(g) = -0.62, r(p) = -0.74) with ADG, whereas residual feed intake was not (rg = -0.04, r(p) = -0.06). Genetically, both residual feed intake and feed conversion ratio were negatively correlated with direct effects of 200-d weight (r(g) = -0.45 and -0.21) and 400-d weight (r(g) = -0.26 and -0.09). The correlations between the remaining traits and the feed efficiency traits were near zero, except between feed intake and feed conversion ratio (r(g) = 0.31, r(p) = 0.23), feed intake and residual feed intake (r(g) = 0.69, r(p) = 0.72), and rib fat depth and residual feed intake (r(g) = 0.17, r(p) = 0.14). These results indicate that genetic improvement in feed efficiency can be achieved through selection and, in general, correlated responses in growth and the other postweaning traits will be minimal.

Adipose Tissue↗
PubMed2000

Genetic analyses of live-animal ultrasound and abattoir carcass traits in Australian Angus and Hereford cattle.

In order to estimate genetic parameters, abattoir carcass data on 1,713 Angus and 1,007 Hereford steers and heifers were combined with yearling live-animal ultrasound measurements on 8,196 Angus and 3,405 Hereford individuals from seedstock herds. Abattoir measures included carcass weight (CWT), percentage of retail beefyield (RBY), near-infrared measured intramuscular fat percentage (CIMF), preslaughter scanned eye muscle area (CEMA), and subcutaneous fat depth at the 12th rib (CRIB) and at the P8 site (CP8). Ultrasound scans on yearling animals included 12th-rib fat depth (SRIB), rump fat depth at the P8 site (SP8), eye muscle area (SEMA), and percentage of intramuscular fat (SIMF). Records on CWT were adjusted to 650-d slaughter age, and the remaining abattoir traits were adjusted to 300-kg CWT. Scan data were analyzed treating records on males and females as different traits. Multivariate analyses were performed on a variety of trait combinations using animal model and REML algorithm. Heritability (h2) estimates for CWT, RBY, CIMF, CP8, CRIB, and CEMA were .31, .68, .43, .44, .28, and .26, respectively, for Angus and .54, .36, .36, .08, .27, .38, respectively, for Hereford. Pooled across sexes, h2 estimates for SIMF, SP8, SRIB, and SEMA were .33, .55, .51, and .42, respectively, for Angus and .20, .31, .18, and .38, respectively, for Hereford. Genetic correlations (r(g)) between the same pair of carcass traits measured at yearling through scanning and directly at the abattoir were moderate to strongly positive, suggesting that selection using yearling ultrasound measurements of seedstock cattle should result in predictable genetic improvement for abattoir carcass characteristics. Estimates of r(g) between the scanned fat measurements and RBY were negative, ranging from -.85 for Angus heifers to -.05 for Hereford heifers. Also, the estimates of r(g) between SEMA and the fat records measured at the abattoir were negative and ranged from -.94 in Hereford heifers to -.02 in Angus heifers.

Adipose Tissue↗
PubMed1997

Assessing the efficiency of multiplicative mixed model equations to account for heterogeneous variance across herds in carcass scan traits from beef cattle.

Data (n = 2,658) from live animal ultrasonic measures from 17 Angus herds were used to evaluate a multiplicative mixed model that incorporates scaling factors to correct for across-herd heterogeneity of variance. Traits included were ribeye muscle area (EMA), surface fat at the P8 site (P8), surface fat between the 12th and 13th ribs (RIB12), and weight at scanning (WEIGHT). Cattle ranged in age from 501 to 698 d and represented 291 contemporary groups. Data were initially analyzed using single-trait, animal model, Method R procedures to estimate variance components and heritabilities (h2). These estimates were incorporated into a multiplicative mixed model that simultaneously estimates breeding values (EBV) and heterogeneity factors. Re-estimation of h2 after scaling the data with the correction factors was explored to obtain a measure of the improvement in the genetic evaluation and to detect changes in ranking of individuals and herds. Initial h2 estimates for EMA, P8, RIB12, and WEIGHT were .36, .39, .29, and .48, respectively. Scaling factors ranged from .25 for P8 in a herd with eight records to 1.96 for RIB12 in a herd with 86 individuals. Re-estimates of h2 increased by an average of 4.2% for all the traits as a result of correcting for heterogeneity. Deviations of new scaling factors were within expectations. Correlations between EBV with and without heterogeneity correction were greater than .97 for all the traits. However, some substantial re-rankings of herds were observed for some traits in the smaller herds.

Analysis of Variance↗
PubMed1992

Additive and nonadditive differences in postweaning growth and carcass characteristics of Devon, Hereford, and reciprocal-cross steers.

Postweaning growth and carcass characters of 110 steers from a complete two-breed diallel of the Devon and Hereford breeds were examined under two environments. Additive and nonadditive effects were estimated using linear contrasts for several growth and carcass traits. Steers from each of the four breed groups were grown postweaning to slaughter in high- and low-nutrition environments. Weights were recorded every 2 mo. At slaughter, hot carcass weight, longissimus muscle area, kidney and channel fat, and subcutaneous fat at nine sites were measured. Heterosis for postweaning growth rate was 3.9% (P less than .01) and for slaughter weight 5.0% (P less than .01). Within the low-nutrition environment during periods of slow and fast growth, the Devons and Herefords performed differently. The growth rate of the steers differed in the two environments; however, heterosis for slaughter weight was of the same magnitude in both environments. No differences existed between the straightbreds or between the reciprocal crosses for slaughter weight. Crossbred carcasses were 7.4% heavier (P less than .01) than the straightbred carcasses; however, this effect was removed after adjustment for differences in slaughter weight. Heterosis for longissimus muscle area and carcass fatness were not significant after adjusting for carcass weight. Additive differences occurred for carcass traits. Devon carcasses had more kidney and channel fat (P less than .05) at a constant hot carcass weight and differences occurred in the partitioning of fat within the subcutaneous depot. No significant maternal effects were observed for the carcass traits measured. Crossbreeding increased carcass weight without altering composition, and relative performance was not affected by the diverse environments.

Adipose Tissue↗
PubMed1990

Variation in intracellular P1P4-bis(5'-adenosyl) tetraphosphate (Ap4A) in virus-infected cells.

The effect of virus infection on the intracellular concentration of the proposed stress alarmone P1P4-bis(5'-adenosyl) tetraphosphate (Ap4A) has been examined in Vero cells. Compared with exposure to 0.8 mM-Cd2+, which causes a 30-fold increase in Ap4A, infection with simian virus 40 and poliovirus causes only a 2-fold increase, whereas herpes simplex virus type 1 results in a decrease in Ap4A during the course of the infection.

Animals↗
PubMed1983

Pindolol and propranolol in patients with angina pectoris and normal or near-normal ventricular function. Lack of influence of intrinsic sympathomimetic activity on global and segmental left ventricular function assessed by radionuclide ventriculography.

To investigate the role of intrinsic sympathomimetic activity on left ventricular (LV) function during antianginal therapy with beta-adrenoreceptor antagonists, 23 patients with chronic, exercise-induced angina pectoris and normal or near normal LV function underwent radionuclide ventriculography at rest and during exercise, during 3 randomly allocated periods: (a) treatment with oral propranolol, a drug without intrinsic sympathomimetic activity, 40 to 80 mg 4 times a day; (2) treatment with pindolol, a drug with marked intrinsic sympathomimetic activity, 5 to 10 mg 2 times a day; and (3) a control period. During the control period, the LV ejection fraction decreased from rest (58.9 +/- 8.2%) to exercise (54.3 +/- 10.7%), and the wall motion score decreased from 0.57 +/- 1.08 at rest to 2.39 +/- 2.10 during exercise, p less than 0.001. After propranolol, the ejection fraction did not change significantly at rest (57.2 +/- 8.1%) but improved during exercise (56.8 +/- 11.8%), compared with control values. After pindolol, the ejection fraction did not change at rest (57.9 +/- 8.6%) but improved during exercise (56.9 +/- 8.1%), compared with control values. Similarly, the wall motion score after administration of both agents did not change significantly at rest, but improved during exercise (p less than 0.001). The number of anginal episodes, nitroglycerin tablets consumed, and magnitude of S-T segment depression decreased significantly with both pindolol and propranolol. With both drugs, a similar improvement in exercise tolerance and a similar decrease in exercise heart rate and blood pressure were obtained. It is concluded that pindolol and propranolol, beta-adrenoreceptor antagonists with and without intrinsic sympathomimetic activity, respectively, have similar effects on global and regional LV function in patients with angina pectoris, at doses producing equal suppression of exercise heart rate and similar antianginal effect.

Adult↗