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Biomedical subjects

D G Jones

Publications and source records attributed to D G Jones.

At least 73 records · Page 4Linked to original sources
PubMed1998

CDA hones its marketing message.

This article discusses the many tacks CDA has taken with its marketing campaigns over the years. The keys to success have been reasonable goals and sufficient funds to make an impact. The current campaign, while underfunded due to budget constraints, carries on the successful theme of positioning CDA and its member dentists as the trusted sources of dental information for consumers, legislators, and health care decision-makers. An accompanying article discusses the proposed ADA national marketing campaign.

Advertising↗
PubMed1997

Aging, dementia and care: setting limits on the allocation of health care resources to the aged.

This article explores the ethical dimensions behind care of the elderly and considers whether younger people should be given priority over the aged in the provision of health care resources. It is argued that age is a relevant consideration in decisions concerning the allocation of health care. The notions of a 'natural life span' and a 'tolerable death' are discussed and on this basis I conclude that while the interests and claims of the elderly must be protected, the use of unlimited resources in the pursuit of life extending measures cannot be justified. When traditional ethical principles are applied to care of the aged they have to be viewed in a modified fashion. The nature of dementia is such that integrity in caregiving has to take account of the patient's premorbid self. I argue that the morally appropriate response to demented patients excludes acute-care, life-extending medicine, but neither does it advocate active euthanasia. The aim is to find a middle ground between treating the demented too aggressively and failing to give them sufficient treatment.

Aged↗
PubMed1997

Persistence of immunity of Nematodirus battus infection in lambs.

Fifty-four Greyface Suffolk lambs aged 3 months were allocated to six groups of seven and one group of 12. Three groups were infected continuously with Nematodirus battus larvae (L3) over a 7-week period and three groups remained worm-free. One week after the last larval dose all six groups were treated with anthelmintic and challenged with a single dose of 30,000 N. battus L3 either 1, 6 or 12 weeks post-treatment (PT) and killed 10 days later. A seventh continuously infected and treated group (n = 12) was segregated into four sub-groups of three lambs which were used as tissue cell count controls and provided data on local cellular responses prior to challenge. Lambs in the first sub-group were killed immediately after anthelmintic treatment and those in the other sub-groups were killed on the same day that the lambs in the other main groups were challenged. Overall post-challenge worm burdens did not differ significantly between previously infected and challenge control groups although they were significantly reduced in both treatment groups by Week 12 PT. The principal manifestation of acquired immunity that was maintained throughout 12 weeks without further infection was retardation in larval development. There was also evidence of preferential rejection of male worms from immune lambs. Local mast cell, but not eosinophil, responses were significantly enhanced by previous infection and persisted up to Week 12 PT. The numbers of bone marrow eosinophils were significantly increased as a result of previous infection and this response persisted up to Week 12 PT. During primary infection anti-L4 and anti-adult worm IgG responses were significantly increased in the previously infected lambs by Day 42 post-infection. Eosinophil responses during this period did not differ between groups. The inflammatory cell responses, coupled with the parasitological observations, suggest that immunity to previous infection is maintained for up to 12 weeks PT without further antigenic stimulation. This 'immunological memory' may have waned partially after 6 weeks PT although the superimposition of age resistance may have masked the effect.

Animals↗
PubMed1997

Anatomy departments and anatomy education: reflections and myths.

This report is based on the basic postulate that if the overall goal of anatomy departments is to function as vigorous academic and scholastic communities welcoming research and innovative thinking, there will be implications for the nature of anatomy teaching. In developing this theme, perceptions about the meaning of the term "anatomy" are explored, as are the repercussions of teaching anatomy entirely within the context of a medical curriculum. There have been a variety of responses to the perceived demise of anatomy, resulting in a discipline that is heterogeneous, both in terms of teaching and research emphases. The options open to university departments are assessed by way of the model of third-wave departments, with their characteristics of excellence, flexibility, planning, networking, and risk-taking. The consequences of this model for anatomy departments include the importance of a research emphasis, a close conceptual link between teaching and research, and a structural base for the research. In view of these consequences, three distinct forms of teaching are recognized: undergraduate teaching to medical and other health science students, undergraduate teaching to science students, and postgraduate teaching. Some of the distinctive features of the two forms of undergraduate teaching are explored. Various central contentions (myths) regarding anatomy departments and anatomy education are rejected.

Academic Medical Centers↗
PubMed1997

Reassessing the importance of dissection: a critique and elaboration.

How important is dissection in basic anatomical education? In an attempt to provide an adequate basis for a rigorous answer to this seminal question, a number of subsidiary questions are asked. What is the value of the direct experience of human cadavers? What is the value of dissection? Where does the use of prosections fit in? What are the alternatives? The emphasis throughout is on the need for hard data and serious analysis. To this end, a variety of issues are raised for debate, including the variety of responses demonstrated by students to human cadavers, the importance of dissection for introducing students to aspects of the clinical ethos, the problems raised by students who attempt to bypass dissection, and the relative costs and educational merits of using cadavers and alternative approaches (including prosections and computer-based approaches). The relevance of the debate for histology teaching is also raised.

Anatomy↗
PubMed1997

Skeletal muscle extra-aortic counterpulsation in dogs with dilated cardiomyopathy.

Skeletal muscle extra-aortic counterpulsation was performed in seven dogs with dilated cardiomyopathy. A left latissimus dorsi dynamic descending thoracic aortomyoplasty was used as the autologous counterpulsator. Pulse train stimulation in diastole was used to initiate contraction and fibre type transformation. Two of the dogs died within 48 hours of surgery. The device was successfully activated in the five remaining dogs, but in one individual it failed within 48 hours of activation. Serial echocardiographic examinations of dogs in which the device functioned successfully (n = 4) showed trends towards the decrease in the left ventricular systolic internal dimension, left ventricular diastolic internal dimension, E-point to septal separation and left atrial diameter in systole seven to 14 days following the procedure, although these changes failed to persist in the long-term. The results suggest that skeletal muscle for cardiac assistances such as extra-aortic muscle counterpulsation, might be a therapeutic option for dogs with cardiac failure due to dilated cardiomyopathy.

Animals↗
PubMed1996

Studies on caprine responsiveness to nematodiasis: segregation of male goats into responders and non-responders.

Eighty-three 2-4-year-old intact male goats exposed to a combination of artificial and natural challenge were segregated into responders and non-responders by ranking of weekly faecal egg counts (FECs). Retrospective analysis of samples over a 15-week-period showed responders had a statistically lower mean FEC than non-responders. Estimates of repeatability between consecutive egg counts were significant in both groups. The 6 top responders and bottom non-responders were subsequently given an artificial trickle challenge with Teladorsagia circumcincta and Trichostrongylus vitrinus. Mean faecal egg output was significantly lower in responders than non-responders. Peripheral eosinophil numbers following challenge were significantly greater in responder than non-responder goats. Abomasal and intestinal worm burdens were considerably lower in responders, with evidence of retardation of worm development compared to non-responders. Both abomasal and jejunal tissue eosinophil numbers were significantly higher in responders, although there was no difference in mucosal mast cell or globule leucocyte numbers. These results suggest that under temperate climatic conditions, it is possible to segregate male goats into responders and non-responders on the basis of simple parasitological criteria.

Abomasum↗
PubMed1996

Dietary protein influences upon immunity to Nematodirus battus infection in lambs.

Several indices of the immune response to Nematodirus battus infection in lambs offered differing levels of dietary protein were quantified. Lambs were offered either a complete basal ruminant diet (13.2% crude protein (CP)) or the same diet supplemented with fish meal as a source of rumen bypass protein (18.3% CP). Lambs from each dietary treatment group were given either a 7-week continuous trickle infection with N. battus L3 or remained uninfected. All lambs were drenched with anthelmintic at week 8 post-infection (PI), challenged with a single dose of 30,000 N. battus L3 1 week later, and killed 9 days post-challenge (PC). Previous infection induced a significant reduction in worm burdens (p < 0.001) and enhancement of immune responses when compared to challenge controls. Among previously infected lambs, protein supplementation did not reduce worm burdens significantly, although there was a trend for fewer worms in the supplemented lambs. However, a significant increase in mucosal globule leucocyte (p < 0.05) and eosinophil (p < 0.05) numbers was evident. Supplementation (p < 0.05) and previous infection (p < 0.001) both enhanced serum anti-worm IgG titres over time. Peripheral blood eosinophil counts were not affected by supplementation but were significantly elevated over time as a result of previous infection (p < 0.001). Since there were no significant differences in worm burdens of supplemented and unsupplemented previously infected lambs, it was of interest to determine whether lambs possessed an innate ability to regulate their parasite burden. Hence they were re-grouped based on an arbitrary cut-off burden of 1000 worms. High responders (HR) had burdens below 1000 worms, while low responders (LR) had burdens above this value and challenge controls were pooled. The data were re-analyzed based on these groupings and showed significant reduction in worm burdens between all three groups (p < 0.001). Globule leucocytes were the only cell type that appeared to be significantly more abundant in the intestinal mucosa of HR (p < 0.001). Serum antibody responses (p < 0.05) and peripheral blood eosinophil counts (p < 0.01) were significantly elevated over time in accord with the degree of responsiveness. The results of this study suggest that supplementation of protein upon an adequate basal diet of lambs previously exposed to N. battus does not significantly enhance worm regulation despite significant increases in cellular and antibody responses. The immunity acquired is characterized by reduction in worm burdens, elevated anti-worm antibodies and a cellular inflammatory response. The identification of HR and LR essentially shows that when the protein supply is adequate, the predominant host effect influencing the pathogenicity of the parasites is the level of genetically determined susceptibility of the host.

Analysis of Variance↗
PubMed1996

The response of breeding doses to nematodiasis: segregation into "responders" and "non-responders".

Responder and non-responder does were identified from a flock of 95 Scottish cashmere 2-6 year-old does exposed to natural nematode infection over a 12-month period. Every 5 weeks, the does were faecal sampled for worm-egg counts prior to anthelmintic treatment. Responsive and non-responsive individuals were identified on the basis of their cumulative faecal egg count (FEC) rankings: the 8 lowest and 8 highest rankings were deemed to be responders and non-responders, respectively. Retrospective analysis showed that the mean egg count of the 8 responders was significantly lower than that of the 8 non-responders. The selected responders and non-responders were subsequently housed together with 8 randomly selected does from a control line, and given a mixed trickle challenge with Teladorsagia circumcincta and Trichostrongylus vitrinus larvae (L3). Mean responders FEC was significantly lower following artificial infection than that of non-responder and unselected does. Peripheral eosinophilia was significantly greater in responders in the first 3 weeks of this infection. On day 60, the infection was terminated with anthelmintic and 7 days later the goats were given a single challenge of 50,000 T. circumcincta L3. The mean responder worm burden was lower, and exhibited greater evidence of retardation of worm development, than those of non-responder and unselected does. Responders had significantly more mast cells and globule leukocytes post-challenge than did the other 2 groups. These results suggest that under the conditions encountered in this experiment, it is possible to segregate goats into responders and non-responders using simple parasitological criteria, as individual responsiveness is a relatively repeatable phenomenon.

Animal Feed↗
PubMed1996

Sources of situation awareness errors in aviation.

BACKGROUND: Situation Awareness (SA) is a crucial factor in effective decision-making, especially in the dynamic flight environment. Consequently, an understanding of the types of SA errors that occur in this environment is beneficial. METHODS: This study uses reports from the Aviation Safety Reporting System (ASRS) database (accessed by the term "situational awareness") to investigate the types of SA errors that occur in aviation. The errors were classified into one of three major categories: Level 1 (failure to correctly perceive the information), Level 2 (failure to comprehend the situation), or Level 3 (failure to project the situation into the future). RESULTS: Of the errors identified, 76.3% were Level 1 SA errors, 20.3% were Level 2, and 3.4% were Level 3. Level 1 SA errors occurred when relevant data were not available, when data were hard to discriminate or detect, when a failure to monitor or observe data occurred, when presented information was misperceived, or when memory loss occurred. Level 2 SA errors involved a lack of or an incomplete mental model, the use of an incorrect mental model, over-reliance on default values, and miscellaneous other factors. Level 3 errors involved either an overprojection of current trends or miscellaneous other factors. CONCLUSIONS: These results give an indication of the types and frequency of SA errors that occur in aviation, with failure to monitor or observe available information forming the largest single category. Many other causal factors are also indicated, however, including vigilance, automation problems, and poor mental models.

Accidents, Aviation↗