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Biomedical subjects

E J Smith

Publications and source records attributed to E J Smith.

At least 19 recordsLinked to original sources

A comparison of four methods of variance component estimation for heritability of embryonic mortality in turkeys.

A comparison of four methods for variance component estimation to compute heritability of embryonic mortality in the early (Days 1 to 10) and late (Days 21 to 28) incubation period, was performed using Henderson's Method 3, maximum likelihood (ML), restricted maximum likelihood (REML), and minimum variance quadratic unbiased estimator (MIVQUE). Incubation records from Wrolstad Medium White turkeys divergently selected for semen ejaculate volume were the source of data for the present study. Negative sire components of variance were obtained for early mortality by both Henderson's Method 3 and the MIVQUE procedure. Estimates of the sire variance component for the late mortality period were lower (P less than .05) for ML than those obtained using Henderson's Method 3, REML, and MIVQUE. It was concluded that likelihood procedures (ML and REML) are superior for estimating variance components and genetic parameters from unbalanced data.

Analysis of Variance

Genetic variation in total plasma and high density lipoprotein cholesterol and body weight in medium white turkeys.

Plasma total cholesterol (PC) and its high density lipoprotein cholesterol (HDLC) fraction were determined in 700 16-wk-old Medium White turkeys in Generation 15 of selection for low and high semen ejaculate volumes (SEV). The birds examined were from pedigree matings involving 10 sires mated to 100 dams in each line. Mean PC and HDLC were not different between lines and between sexes within lines. Genetic parameters were estimated for PC, HDLC, and BW. Sire component heritabilities estimated based on pooled data from low and high SEV lines for PC and HDLC were -.03 and .26, respectively. Genetic correlations were .05 between PC and HDLC; .13 between PC and BW; and -.34 between HDLC and BW. It was concluded that variation in PC in 16-wk-old Medium White turkeys is largely due to environmental variation and that the genetic component is largely nonadditive. However, a moderate additive genetic component was observed for HDLC. Further, determination of total PC and HDLC at 16 wk of age does not exhibit a potential value as an indicator of future SEV potential.

Animals

Classification of turkeys as low or high volume semen producers using discriminant analysis.

Medium White turkeys in Generation 10 of divergent selection for semen ejaculate volume (SEV) were classified into lines that produce either low or high volumes of semen using a multivariate statistical technique, discriminant analysis. The discriminant function was based on records of hen fertility, embryonic mortality in the early and late incubation periods, and the incidence of pipped eggs. A hit ratio, the proportion of birds correctly categorized as low or high, of .60 was obtained. The discriminant function was subsequently used to classify birds in Generation 12. A misclassification rate of .28 and .48 was obtained for birds in the low and high lines, respectively. It was concluded that the relatively low rates of misclassification indicate a potential method for identifying male and female turkeys as belonging to low or high SEV lines, based on fertility and incubation records.

Animals

Maxillofacial trauma in severely injured patients.

A study was made of maxillofacial trauma in seriously injured patients to determine the likely role of oral and maxillofacial surgeons working in the regional trauma centres proposed by the Royal College of Surgeons of England. There were 153 patients, aged 70 years or less, who sustained major trauma (injury severity score 16 or more) and were admitted directly to the accident departments of the Bristol Royal Infirmary or Derriford Hospital, Plymouth during 1989. Maxillofacial injuries occurred in 50 (33%) of these patients with lacerations present in 39, burns in 1 and facial bone fractures in 28 (18%); soft tissue abrasions and contusions were excluded. The aetiology, patterns of injury, surgical treatment and outcome were reviewed. The implications for the provision of maxillofacial surgical services in regional trauma centres is discussed.

Accidents, Traffic

Performance of early and late feathering broiler breeder females with different feeding regimens.

1. Growth, reproductive characteristics and immunocompetence were evaluated in a line of broiler breeder females segregating at the sex-linked feathering locus when maintained on three feeding regimens with two forms of food in a factorial design. 2. Long-term obesity but not short-term weight gain had deleterious consequences for reproductive characteristics, response to sheep red blood cell antigen, resistance to Escherichia coli and livability. 3. Reproductive performance of early feathering females was superior to that of late feathering ones. Differences were attributed to an association between the allele for late feathering and an endogenous viral locus ev21, which encodes for avian leucosis virus. 4. Reproductive performance of breeders fed crumbles was superior to that of breeders fed a combination of crumbles and fines.

Animal Feed

The influence of ev6 on the immune response to avian leukosis virus infection in rapid-feathering progeny of slow- and rapid-feathering dams.

Endogenous virus (EV) locus ev6 encodes only virus envelope glycoprotein. The influence of ev6 on the immune response to contact infection with hatchmates infected with avian leukosis virus (ALV) was compared in replicate hatches. The ALV Subgroup E-resistant, rapid-feathering (RF) female chickens produced by slow-feathering (SF) and RF dams with and without ev6 were exposed at hatch to hatchmates infected with ALV Subgroup A (Strain RPL-40). The RPL-40 viremia, shedding, and virus neutralizing antibodies were measured among pullets from two hatches at 22 wk of age. Although significant (P less than .05) differences between hatches in the immune response to contact infection were noted among ev6+ pullets, significantly fewer ev6+ pullets seroconverted than their ev6- hatchmates. At 22 wk of age, significantly more lymphomas were also found among ev6+ pullets than among ev6- hatchmates. In flocks wherein both parents and progeny were homozygous resistant to Subgroup E virus, there was no deterimental maternal effect on RF progeny from SF dams that carried ev21. These results also confirm that selection for genetic cellular resistance to Subgroup E ALV infection eliminates congenital transmission of EV21.

Animals

Association of a chicken repetitive element with the endogenous virus-21 slow-feathering locus.

The DNA sequences of an endogenous virus ev21-cell junction fragment (JFIL-1), and the pristine ev21 unoccupied region were analyzed. Comparisons of 3' proviral sequences of JFIL-1 with comparable regions of ev2, the prototype Rous-associated provirus (RAV-0), revealed minor single-base substitutions in the transmembrane domain of proviral envelope glycoprotein and the long terminal repeat of ev21. In the cell component of the JFIL-1, insertion of a 9-bp direct repeat and deletion of a guanine deoxynucleotide abolished HaeIII and BalI recognition sites that were present in the pristine region. Upstream from the insertion site, a large region was 71 and 75% homologous with dispersed chicken repetitive (CR1) elements associated with vitellogenin and very low density apolipoprotein II genes, respectively. Southern blot hybridizations and comparisons of CR1 motifs such as polypurine tracts, a tandem imperfect octamer, and 6-bp duplications indicated that this sex-linked, CR1 element (CR1ev21) may be the longest member of this family reported thus far.

Animals

Application of a locus-specific DNA hybridization probe in the analysis of the slow-feathering endogenous virus complex of chickens.

To investigate further the sex-linked, slow-feathering (SF) locus, a DNA hybridization probe that flanks the integration site of endogenous virus ev21 was used to probe Southern blots from a variety of commercial SF White Leghorn (WL), broiler, and endangered lines. After HaeIII digestion of DNA from SF WL, the 5' and 3' provirus-cell junction fragments were seen in addition to a 2.5-kb fragment of cell sequences that was homologous with the viral integration region. The latter polymorphism, which appeared to represent sequences duplicated after integration of EV21, was designated unoccupied repeat URa. Among SF broiler crosses, the same provirus-cell junction fragments were found but the pristine region that represented the 1.6-kb proviral URb was also found. Only URb was found among rapid-feathering (RF) chickens, regardless of breed. Although there was marked (greater than 95%), agreement between the presence of ev21-cell; junction fragments and the SF phenotype among both WL and broilers, Southern blots of DNA from a few commercial SF broiler chickens lacked ev21 junction fragments but some RF revertants harbored ev21 junction fragments. These anomalies suggest that ev21 may not be the sole determinant of the SF phenotype.

Animals

Genetic variation in the incidence of pipped eggs in turkeys selected for low and high semen ejaculate volume.

Genetic variation in embryonic mortality, expressed as embryos that pip their eggshell but do not hatch, was investigated in turkeys selected for low and high semen ejaculate volume (SEV). Through five generations (Generations 10 to 14, inclusive) mean heritability estimates for pipped eggs were .21 and .08 in the low- and high-SEV lines, respectively. Estimates of sire, dam, and within-hatch components of variance suggest greater environmental and maternal effects than genetic influences on the incidence of pipped eggs in turkeys.

Animals

Ankle arthrodesis in the rheumatoid patient.

We studied 11 patients with severe rheumatoid arthritis of the ankle joint who underwent arthrodesis employing the Charnley technique. Results of the procedure were assessed using the Fries score and the ankle evaluation grading system of Mazur et al. Four patients (36%) suffered pin-track sepsis. Three patients also showed delayed union, but sound bony fusion was eventually achieved in all patients.

Adult

Interactions between endogenous virus loci ev6 and ev21. 1. Immune response to exogenous avian leukosis virus infection.

The effects of ev6, ev21, sex, and hatch, were studied with respect to avian leukosis virus (ALV) viremia, cloacal shedding, and antibody response among RPL-40 virus-infected White Leghorns that carried ev6 and ev21 in all combinations. Among the four possible ev genotypes, chickens that carried only ev21 were the most immunologically tolerant to RPL-40 infection. Incidence of RPL-40 viremia was lowest among hatchmates that lacked both ev genes. Analysis of variance indicated significant interactions between ev6 and ev21 with respect to all responses. Among ev21+ slow-feathering (SF) chickens, the incidence of viremia and shedding of RPL-40 was reduced in the presence of ev6 when compared with ev6- hatchmates. Conversely, among ev21- rapid-feathering (RF) chickens, ev6 significantly enhanced the incidence of RPL-40 viremia when compared with ev6- hatchmates. The endogenous virus, ev6, markedly reduced recovery of the endogenous virus (EV21) from plasmas of slow-feathering chickens. When both flocks were terminated at 21 wk of age, significantly more ev21+ SF females had died from or developed RPL-40-induced tumors than ev21- hatchmates.

Animals

Interactions between endogenous virus loci ev6 and ev21. 2. Congenital transmission of EV21 viral product to female progency from slow-feathering dams.

The influence of the endogenous virus ev6 on congenital transmission of EV21, the infectious viral product encoded by locus ev21, and the immune response to exogenous avian leukosis virus (ALV) infection was studied in rapid-feathering (RF) female progeny from four classes of slow-feathering (SF) (ev21+ and RF (ev21-) dams with and without ev6. Apart from transmitting infectious EV21 and ev6 to progency, dam ev genotype did not influence the immune response or shedding of RPL-40. The endogenous virus envelope glycoprotein encoded by ev6, however, completely restricted shedding and congenital transmission of infectious endogenous virus EV21, from SF dams. After 19 wk of exposure to ALV strain RPL-40 infected cage mates, only 11% of the congenitally infected female progeny mounted neutralizing antibodies against RPL-40, whereas 73% of their noncongenitally infected sisters seroconverted. More ev6+ female progeny, however, were shedders of RPL-40 and developed tumors than ev6- sisters. Among progeny from the four classes of dams, EV21 congenitally infected hens had the highest incidence (31%) of RPL-40-induced tumors.

Animals

Molecular analysis of endogenous virus ev21-slow feathering complex of chickens. 1. Cloning of proviral-cell junction fragment and unoccupied integration site.

Sex-linked slow-feathering gene, K, is genetically associated with the presence of an avian endogenous retrovirus ev21 in White Leghorns (WL). An EcoRI fragment corresponding to the endogenous virus ev21-cell junction fragment and a fragment homologous to the proviral unoccupied site (US) were cloned, respectively, from genomic DNA libraries of two WL chickens: an ev21-only female and an ev-negative male. A 1.7-kilobase pairs (kbp) fragment cleaved from the cloned proviral US by the HaeIII restriction endonuclease was the most informative probe to molecularly characterize the occupied and unoccupied integration sites of ev21 locus. Restriction fragment length polymorphism analysis of slow-feathering (SF) and rapid-feathering (RF) chickens from various commercial breeds, using the US HaeIII 1.7-kbp probe, indicated that the complete genetic association between ev21 and SF phenotype is common among other lines of SF chickens and was not restricted to WL. It was also shown that there was at least one additional DNA region highly homologous to DNA sequences flanking the EV21 integration site in the chicken genome. In SF birds of either sex this additional repeat was distinguishable from the site occupied by ev21 (OR) and represents an unoccupied repeat (UR). Analysis of DNA from RF revertant females showed novel patterns of reversion. In Type I RF revertants, RF is associated with the complete excision of proviral ev21 DNA sequences. In Type II revertants, the UR homologous to the cell sequences flanking ev21 integration site is excised, but proviral ev21 sequences remain intact. A hypothesis to explain these types of reversion is suggested. It postulates a close association between OR and UR on the Z chromosome.

Animals