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Biomedical subjects

D G Jones

Publications and source records attributed to D G Jones.

At least 127 records · Page 7Linked to original sources
PubMed1990

Evidence for the presence of nematode-derived acetylcholinesterase in sheep infected with Trichostrongylus colubriformis.

The distribution of acetylcholinesterase isoenzymes in the ovine intestinal nematode Trichostrongylus colubriformis was compared with that in chronically infected and worm-free lambs. Total acetylcholinesterase activity in homogenates of adult T colubriformis was resolved into five isoenzyme peaks following gel electrophoresis and specific esterase staining. Two isoenzymes with electrophoretic mobilities similar to those present in adult worm homogenates were detected in mucosal homogenates and plasma extracts from all of six sheep chronically infected with T colubriformis, but not in similar preparations from two uninfected animals.

Acetylcholinesterase↗
PubMed1989

The New Zealand Report of the cervical cancer inquiry: significance for medical education.

The New Zealand Cervical Cancer Inquiry has elicited considerable interest in Australia as well as in New Zealand. However, relatively little attention has been paid to the future practice of medicine with regard to the relevance of the Inquiry's findings for medical education, although it did recommend the incorporation of ethics teaching into all stages of the medical curriculum, and also urged that attention be paid to communication skills within the curriculum. In this article, I argue that medical ethics teaching should be seen as an essential part of the medical curriculum, with the teaching being integrated closely with the other disciplines that comprise the medical course. To illustrate one possible approach, I have outlined elements of current ethics teaching at the University of Otago. I also have raised what I regard as wider issues for the medical curriculum. These include the need for students to develop a critical facility and an ability to handle conflicting data and attitudes (fostered principally by an understanding of research methods), to appreciate the importance of accountability (fostered in part through group learning activities) and to be aware of the impact of community concerns on the practice of medicine. Another issue which I consider is raised indirectly by the Inquiry concerns the procedures that are used for the selection of students into medical courses.

Attitude of Health Personnel↗
PubMed1989

Effect of cytosine arabinoside on rat cerebral explants: fibroblasts and reactive microglial cells as the primary cellular barrier to neurite growth.

Rat cerebral explants were cultured in the presence or absence of the mitotic inhibitor cytosine arabinoside (AraC) to investigate whether reports of increased neurite outgrowth may be primarily related to a decreased incidence of fibroblastic-reactive microglial cells. Treated explants were exposed to AraC from 7 to 10 days in vitro (DIV) and processed for transmission electron microscopy at 18 DIV. Morphometric analysis of the outgrowth zone revealed a statistically significant decrease in the incidence of fibroblastic-reactive microglial cells (from 12 to 0%), and a significant increase in the incidence of protoplasmic astrocytic-epithelial cells (from 82 to 96%), for AraC-treated explants compared to controls. In contrast, the incidence of fibrous astrocytes was similar to that of control explants (4 and 6%, respectively). Thus, it appears that AraC may primarily enhance neurite growth by curtailing the proliferation of fibroblastic-reactive microglial cells. These results suggest that fibroblastic-reactive microglial cells, rather than fibrous astrocytes, may constitute the primary cellular barrier to neurite growth.

Animals↗
PubMed1989

Relationships between vitamin E status and erythrocyte stability in sheep.

Stability of erythrocytes from sheep with vitamin E deficiency (E-deficient) was compared by two haemolytic tests, one based on osmotic fragility in hypotonic saline and the other on detergent sensitivity in Tween 20. Relationships between haemolysis, plasma alpha-tocopherol concentration and creatine kinase (CK) activity were evaluated. E-deficient animals were clinically healthy but had elevated (greater than 1000 iu per 1) CK activities and low (less than 1 mumol per 1) alpha-tocopherol concentrations compared with control sheep (less than 500 iu per 1 and greater than 1.5 mumol per 1, respectively). Erythrocytes from E-deficient sheep were markedly more susceptible to detergent treatment than those from controls, but osmotic fragility was similar in both groups. Detergent sensitivity was directly related to plasma alpha-tocopherol concentration and CK activity but not to erythrocyte glutathione peroxidase activity. Within 24 h of supplementation (300 mg alpha-tocopherol subcutaneously) of E-deficient sheep, plasma alpha-tocopherol concentrations were increased, CK activities decreased and erythrocyte susceptibility to detergent-induced haemolysis was significantly reduced. Concentrations of alpha-tocopherol returned rapidly (less than 3 days) to pre-supplement values, although decreased haemolytic responses persisted longer (greater than 7 days). Cells from E-deficient animals were protected against detergent-induced haemolysis by preincubation with alpha-tocopherol in vitro. The results indicate that detergent sensitivity of erythrocytes may provide the basis of a simple functional test for vitamin E deficiency in sheep.

Animals↗
PubMed1989

Recent developments in trace element metabolism and function: trace elements, disease resistance and immune responsiveness in ruminants.

Evidence for the influence of trace elements on disease resistance in ruminants is reviewed with emphasis on susceptibility to infection in vivo during the more common deficiencies (copper, selenium and cobalt). Copper deficiency associated with increases in pasture molybdenum increased the susceptibility of lambs to microbial infections. Under experimental conditions, dietary molybdenum decreased the establishment of abomasal and intestinal nematodes but not their pathogenicity to lambs. Molybdenum may enhance inflammatory responses leading to parasite rejection by the host. Decreased incidence of metritis in selenium-treated dairy cows provides a rare example of an association between selenium deficiency and decreased disease resistance. Improved antibody responses following selenium administration have also been found in sheep. Cobalt deficiency has reduced lamb survival and increased susceptibility to parasitic infection transiently in cattle and lastingly in sheep. In copper-, selenium- or cobalt-deficient sheep and cattle, there are many reports of impaired leucocyte and lymphocyte responses to in vitro challenges, but their relevance to disease resistance in vivo is unproven. Disease resistance may have priority for limited micronutrient supplies, leaving other processes vulnerable.

Animals↗
PubMed1989

Brain birth and personal identity.

The concept of brain birth has assumed a position of some significance in discussions on the status of the human embryo and on the point in embryonic development prior to which experimental procedures may be undertaken on human embryos. This paper reviews previous discussions of this concept, which have placed brain birth at various points between 12 days' and 20 weeks' gestation and which have emphasised the symmetry of brain birth and brain death. Major developmental features of brain development are outlined, including the gradualness with which new features generally appear, and also the electroencephalogram (EEG) characteristics of premature infants. From this it is concluded that, if the concept of brain birth is a valid one, it should be placed at 24-28 weeks' gestation. More importantly, it is concluded that the differences between brain development and brain death throw doubt on the concept itself.

Beginning of Human Life↗
PubMed1989

Automated medication dispensing: the ATC 212 system.

Innovative technology is currently being designed and produced that will change the way hospital pharmacy is practiced in the future. Automated technology is becoming a powerful component of health care as human resources become scarce. The report describes a technology currently in use at a large general acute care hospital. This new automated system assists the pharmacy department by packaging and dispensing medications to be used in the centralized, computer supported cart-filling process. The ATC 212 System (Baxter Healthcare Corporation, Deerfield, IL) was reviewed and selected as a tool to enhance pharmacy operations. The system has made a positive impact on the unit dose centralized cart-fill operations. A reduction of one full-time technician, a reallocation of pharmacists' time and an increase in productivity and operational flexibility has been realized as a result of the ATC 212 system implementation.

Automation↗
PubMed1988

Extracorporeal shock wave lithotripsy. Use of antibiotics to avoid postprocedural infection.

Extracorporeal shock wave lithotripsy (ESWL) has the potential to revolutionize the treatment of urolithiasis, but its success depends in part upon minimizing potential sequelae. Although ESWL is safe, effective, and relatively economical, one complication can be urosepsis, resulting from liberation of bacteria when the stones disintegrate. Patients who are at increased risk of infection are those who have existing urinary tract infection; perioperative urologic manipulation; infected stones; predisposition for infectious endocarditis; or multiple, large, or complex stones. If urosepsis occurs, it usually requires prolonged hospitalization, which obviates any cost-benefits that can be accrued from ESWL. Prophylactic use of an antibiotic before ESWL is rational and cost-effective. Ideally, the antibiotic should possess a spectrum of activity against the most likely bacteria to be encountered, require a limited number of doses, and offer the flexibility of sustained coverage in the event that the procedure is delayed. Our experience at Presbyterian Hospital of Dallas supports the use of a long-acting cephalosporin for the prevention of infections following ESWL.

Anti-Bacterial Agents↗
PubMed1988

Blood biochemical reference values for farmed red deer.

The activities and concentrations of 30 whole blood and plasma constituents including enzymes, substrates, electrolytes and vitamins were determined in samples from 91 clinically healthy farmed red deer (Cervus elaphus) hinds ranging in age from one to 15 years. The hinds were randomly selected from a herd maintained on a mixture of reseeded and permanent hill pasture at an experimental research station in north east Scotland. The results were analysed statistically and the calculated means, standard errors and tolerance intervals provide a basis for diagnostic clinical chemistry in red deer. The data are compared with data from earlier reports on blood biochemistry in deer and other livestock species.

Animals↗
PubMed1988

External fixation and recovery of function following fractures of the distal radius in young adults.

The functional recovery from Colles' fracture was studied prospectively over a 1-year period in 106 patients randomized to treatment by plaster or external fixation. Although external fixation allows immediate mobilization of the wrist and leads to a much better anatomical result, these factors did not permit any improvement in the wrist's early functional recovery. One year following injury the grip strength of the fixator-treated group was significantly superior to that of the plaster-treated patients.

Adult↗
PubMed1988

Silastic foam in injured patients.

Four dressing techniques are described; these techniques enable patients with granulating wounds complicating skeletal injuries to be treated as outpatients. The patients perform their own dressings, thus reducing demands on nursing services and freeing hospital beds. In a study of 63 patients there was no problem in managing the wounds from weekly outpatient clinics; good wound healing was achieved.

Bandages↗
PubMed1988

Estimation of the numerical density of synapses in rat neocortex. Comparison of the 'disector' with an 'unfolding' method.

The numerical density of synapses in the molecular layer of the parietal cortex of normal 28-day-old rats has been estimated by using two stereological methods, namely an unfolding technique and the disector method. For the unfolding technique it was assumed that the synapses formed a polydispersed population of disc-shaped particles. The technique also relies upon various assumptions regarding the size, shape and projection of synapses in the plane of section, these assumptions producing a result that is biased to an unknown extent. Such simplifying assumptions are unnecessary for the disector method. The mean +/- S.E.M. numerical density of synapses was found to be 2.16 +/- 0.14 x 10(9)/mm3 using the disector method. This was not significantly different (paired t-test; P less than 0.05) from the value of 2.41 +/- 0.22 x 10(9)/mm3 obtained using the unfolding technique with correction for truncation ('lost caps'). When the unfolding method was used without a correction for lost caps the numerical density was 1.98 +/- 0.10 x 10(9)/mm3, a value also not significantly different from that obtained using the disector method. The mean projected height (Hs) of the synaptic particles was also determined using both procedures; the results were not significantly different. When the variances of the final estimates and the time taken to carry out the procedures described were taken into account, it was estimated that the disector method was about 86% more efficient than the unfolding method with capping correction. Although the unfolding method can give essentially similar values for the numerical density of synapses to those obtained by the disector method, it is biased and much less efficient. It is concluded, therefore, that the disector method is the superior method for the estimation of the number and size of particles such as synapses, particularly when they have complex spatial configurations.

Animals↗
PubMed1988

Digital techniques for luminescence detection in liquid chromatography with an intensified linear photodiode array.

The use of a rapid-scanning fluorescence detector in liquid chromatography is examined in the context of its potential contribution in pharmaceutical and biomedical analysis. The data generated by an intensified linear photodiode array detector is presented as an isometric plot of (I(em),lambda(em),t) at a defined excitation wavelength. Techniques examined for peak homogeneity assessment include: emission spectral normalisation at points through the chromatographic peak profile, second order differentiation (d(2)I/dt(2)) and the fluorescence emission ratio chromatogram, generated by calculating the ratio of emission intensifies at two defined emission wavelengths, at all points in the time domain elution profile. These techniques are illustrated with reference to some polynuclear aromatic hydrocarbons and to the beta-blocker drug atenolol and its related impurities. Future developments of this new detector technology in LC are also considered.

Journal Article↗