Biomedical subjects
Publications and source records attributed to R E Wright.
The case of a 41-year-old man with myelofibrosis who presented with anaemia and splenomegaly is described. Ultrasound examination revealed several multiple circumscribed hypoechoic masses adjacent to both kidneys. The lesions were confirmed by computed tomography (CT) and biopsy of them revealed extramedullary haematopoietic tissue.
This paper examines the relationship between parental education and child mortality in Burundi using data collected in the 1987 Demographic and Health Survey. Proportional hazards models are estimated to examine this relationship, while holding constant other known child mortality determinants. Parental education proves to be a key factor in explaining differences in child mortality, the effect of maternal education being particularly strong compared to paternal education.
Eight Hereford heifer calves were infested 28 times over a 64-d period with approximately 49,560 Dermacentor albipictus (Packard) larvae per calf. The fecundity of partially engorged and small, fully engorged female ticks, prematurely removed by grooming behavior of the calves, were compared. A total of 3,532 females of various engorged weights was collected from all calves, resulting in a mean female tick yield of 1.78% based on the number of larvae used for all infestations. The ratio of partially to fully engorged females was 1:16. Female oviposition success was 96%. The mean (+/- SE) values for female weight, number of larvae, and percentage larval eclosion of 50 partially engorged females that ranged in weight from 54 to 397 mg was 174 +/- 99, 1,272 +/- 931 and 85 +/- 14, respectively. The correlation between preoviposition weight and number of larvae from partially engorged females was highly significant (r = 0.95, P less than 0.0001). A prediction model (Y = -354.6 + 9.07X) showed that the preoviposition weight of partially engorged females and larval fecundity from a separate study was highly correlated (r = 0.92, P less than 0.0001). There was no significant difference between mean values of larval numbers and percentage eclosion for partially engorged and small, fully engorged females of similar weight.
Thin-layer chromatography of the cuticular lipids of horse flies from Oklahoma revealed that hydrocarbon was the major lipid class present. The hydrocarbon fraction was composed of n-alkanes and methyl branched alkanes with only a small amount of alkenes present. Gas chromatography of the isolated cuticular hydrocarbons from a single species, Tabanus abactor Philip, showed no major differences in the profiles between individuals or between the sexes. Analysis of extracts of fresh, frozen, and pinned specimens yielded nearly identical hydrocarbon profiles. Profiles of several species were examined and found to be unique for each. Three species with similar morphological characteristics and similar geographical ranges. Tabanus abdominalis F., T. limbatinevris Macquart, and T. sulcifrons Macquart, were differentiated easily by comparison of the hydrocarbon profiles.
A successful attempt was made to mechanically transmit bovine leukosis virus (BLV) from a BLV-infected cow with a normal lymphocyte count to sheep by inoculation with horse fly (Tabanus abactor) mouthparts. After interrupted natural feeding, horse flies were anesthetized with CO2. Mouthparts were severed and pooled into a tissue grinder containing medium. Five inocula containing the mouthparts of 10 flies each, and 5 inocula containing the mouthparts of 20 flies each, were prepared and inoculated SC in the right axilla of 10 BLV antibody-negative sheep. Five additional sheep served as controls. Serum samples were collected at 2-week intervals and tested by agar gel immunodiffusion for BLV antibodies. One sheep injected with 20 mouthparts developed antibodies to BLV at 10 weeks after inoculation. Six months after inoculation with fly mouthparts, 1 BLV antibody-negative sheep was randomly selected from each treatment group and injected, in the left axilla, with 3 ml of blood from the donor cow to confirm susceptibility of the sheep. All 3 sheep developed antibodies to BLV within 4 weeks.
A mark-recapture technique was used to estimate daily populations of host-seeking Tabanus abactor Philip. Daily population estimates were calculated for 31 and 37 d for areas of 2.1 km2 and 4.6 km2 for 1982 and 1983, respectively. In 1982, population estimates ranged from 22,767 to 2,125,322 flies/2.1 km2 per d with a mean of 467,277 flies/d. In 1983, population estimates ranged from 48,962 to 2,794,389 flies/4.6 km2 per d with a mean of 759,616 flies/d. The estimated average number of host-seeking females per hectare was 2,225 (0.22 flies/m2) and 1,651 (0.17 flies/m2) for 1982 and 1983, respectively. Although daily population estimates fluctuated greatly, primarily because of fluctuation in recapture rates, seasonal trends during both years were similar. The estimates calculated in this study appear to be representative of the population of T. abactor in northcentral Oklahoma based on previous studies determining seasonal abundance.
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A 12-year comparison of changes in the distribution of age, sex and level of functioning, as well as in life expectancy for mentally retarded persons in Canadian institutions has been reported. The major findings of the study corroborate, for the most part, studies from other parts of the developed world despite differences in measures of mortality. Several trends have emerged from the data which will have implications for long-term planning.
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Adult age differences on a variety of free recall measures were examined. Although primary memory capacity was found to be the same in young and old adults, there was a smaller recency effect in the older group. Recall of primacy items was also less for that group. However, the pattern of serial position effects was the same for the two age groups. Similarly, there was no age difference in the development of the strategy of recalling recency items early in the output sequence. Young adults showed the typical negative recency effect in final free recall, and old adults the absence of a positive recency effect. The results indicate that the lower level of recall of old, relative to young, adults cannot be attributed to a qualitative difference in the way the two age groups approach a free recall task.
Adult age differences were examined for relative frequency judgments on a task in which categories had either zero, one, three, or five instances in a study list. Judgments required selecting from pairs of category names which member had the greater representation of instances in the prior list. Contrary to the results obtained in earlier studies using a task in which discrete events vary in frequency of occurrence, an age difference favoring young adults over elderly adults in accuracy of frequency judgments was found for categories. Neither instructional variation (incidental learning vs. intentional learning) nor variation in priming (cuing vs. noncuing with the list of categories prior to the study trial) yielded either main effects or interaction effects with age. The results were interpreted in terms of an age deficit in either the storage or the retrieval of memory traces of category names established by the automatic elicitation of implicit associative responses to instances of taxonomic categories.
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A survey of South Carolina diary cattle in 12 commercial herds was conducted, using serologic testing to determine the frequency and impact on reproduction of bluetongue (BT) and bovine parvovirus (BFV) infections. Results of the study of serum antibodies titers and dairy cattle health records indicated that the majority of the cattle surveyed was adequately protected against the major reproductive tract diseases through vaccination programs. The frequency of reproductive dysfunction was common in vaccinated herds, however. Six of the 12 herds in the survey had cattle which were BT serotest reactors, although total numbers of these reactor cattle were relatively small. Further, reproductive performance of reactor cows indicated that BT was of little consequence and was not associated with reproductive problems. All herds contained BPV serotest reactors and the latter comprised 59.7% of the total number of cows surveyed. The BPV seroreactor cows were commonly associated with the group of reproductive problem cows which experienced higher rates of embryonic mortality and more services per conception than did nonreactor cattle. The results of the survey emphasize the need for continued investigation and efforts to control BT, and especially BPV infection, in dairy cattle.
The performance of young and old adults was compared in two different situations to investigate the reasons why the latter are especially poor at divided attention tasks. Although the two experimental tasks were quite different, one a single task and the other time-sharing, task difficulty was manipulated in a similar fashion in both situations. Specifically, in both tasks difficulty was varied by manipulation of number of items to be rehearsed and number of mental operations necessary for successful performance. The most salient difference in task demands, that is, divided versus nondivided attention, had little effect on results. Performance of both age groups declined as task difficulty increased, with the decline being greater and more rapid for the older subjects. Results are discussed in terms of competition for limited processing capacity in working memory.