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Biomedical subjects

J A Moran

Publications and source records attributed to J A Moran.

At least 19 recordsLinked to original sources
PubMed2006

Low stomatal and internal conductance to CO2 versus Rubisco deactivation as determinants of the photosynthetic decline of ageing evergreen leaves.

A novel A-Ci curve (net CO2 assimilation rate of a leaf -An- as a function of its intercellular CO2 concentration -Ci) analysis method (Plant, Cell & Environment 27, 137-153, 2004) was used to estimate the CO2 transfer conductance (gi) and the maximal carboxylation (Vcmax) and electron transport (Jmax) potentials of ageing, non-senescing Pseudotsuga menziesii leaves in relation to their nitrogen (N) content and protein and pigment composition. Both gi and the stomatal conductance (gsc) of leaves were closely coupled to Vcmax, Jmax and An with all variables decreasing with increasing leaf age. Consequently, both Ci and Cc (chloroplastic CO2 concentration) remained largely conserved through successive growing seasons. The N content of leaves, as well as the amount of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and other sodium dodecyl sulfate-soluble proteins, increased during the first three growing seasons, then stabilized or decreased only slightly afterwards. Thus, the age-related photosynthetic nitrogen use efficiency (PNUE) decline of leaves was not a consequence of decreased allocation of N towards Rubisco and other proteins involved in bioenergetics and light harvesting. Rather, loss of photosynthetic capacity was the result of the decreased activation state of Rubisco and proportional down-regulation of electron transport towards the photosynthetic carbon reduction (PCR) and photorespiratory (PCO) cycles in response to a reduction of CO2 supply to the chloroplasts' stroma. This study emphasizes the regulatory potential and homeostaticity of Cc- rather than photosynthetic metabolites or Ci- in relation to the commonly observed correlation between photosynthesis and gsc.

Carbon Dioxide↗
PubMed2001

Desiccation, cryopreservation and water relations parameters of white spruce (Picea glauca) and interior spruce (Picea glauca x engelmannii complex) somatic embryos.

Effects of drying and cryopreservation on survival of spruce (Picea glauca (Moench) Voss and Picea glauca x engelmannii complex) somatic embryos (SEs) were investigated with the aim of developing simple and robust protocols for embryo storage. Somatic embryos dried over salt solutions of known water potential (Psi) survived removal of virtually all free water, to a relative water content (RWC) of approximately 0.13, a value similar to that for spruce zygotic embryos from dry seed. Desiccated SEs also survived subsequent freezing in liquid nitrogen, without the addition of cryoprotectant or pre-culture steps. Highest survival (> 80%) after freezing in liquid nitrogen was in embryos pre-dried to Psi of -15 to -20 MPa, which yielded RWC close to predicted bound (apoplastic) water values. Low (< 35%) or no survival after freezing was observed in embryos pretreated at higher Psi (above -5 MPa) or at very low Psi (-540 MPa, using silica gel), respectively.

Cryopreservation↗
PubMed2000

Differentiation among effects of nitrogen fertilization treatments on conifer seedlings by foliar reflectance: a comparison of methods.

Analysis of reflectance can be used to estimate foliar concentrations of photosynthetic pigments, thus providing information on the physiological status of green plants. We compared several methods of reflectance analysis for the capacity to differentiate among effects of fertilization treatments across different irradiances on seedlings of Engelmann spruce (Picea engelmanii Parry ex Engelm.). Seedlings were grown in two light treatments (0 and 60% shade) and three nitrogen (N) treatments (10, 25 and 100 mg N l-1) for one growing season, after which foliar reflectance of the needles was measured. Five indices were tested: R550 (% reflectance at 550 nm); red edge position; the ratio R698:R760; the structure independent pigment index (SIPI); and the photochemical reflectance index (PRI). Both the light and nutrient treatments significantly affected foliar chlorophyll a and b and carotenoid concentrations. Among the indices tested, R550, red edge position and R698:R760 ratio were related to chlorophyll concentration, and were significantly affected by both light and N treatments. Both SIPI and PRI were related to chlorophyll and carotenoid concentrations. Among these relationships, PRI was affected by both treatments, whereas SIPI was sensitive to N treatment but not to light treatment. All five indices were weakly but significantly correlated with growth as measured by dry weight.

Carotenoids↗
PubMed1998

IL-3-mediated enhancement of particulate antigen presentation by macrophages.

Mice were exposed to interleukin- (IL-) 3 in vivo by injection of tumor cells transfected with the IL-3 gene. At 10 days post tumor injection, bone marrow cells were recovered, pulsed with particulate antigen in the form of ovalbumin (Ova)-coated magnetic beads, and tested for their ability to present antigen via class I to an Ova/class I-restricted T cell hybridoma. Cells from IL-3-stimulated mice exhibited a marked increase in antigen presentation compared with cells from mice injected with control non-cytokine-secreting tumor cells. These cells were markedly more efficient at presenting particulate Ova antigen than in presenting soluble Ova. Based on adherence, radiation resistance, and surface markers, the cells presenting antigen appear to be in the macrophage cell lineage. These cells are susceptible to lysis by antigen-specific cytotoxic T lymphocytes, which may contribute to limiting the effectiveness of antitumor responses.

Animals↗
PubMed1996

Measuring the effectiveness of a pilot continuing medical education program.

OBJECTIVE: To evaluate a learner-centred, small group CME program intended to improve the clinical performance of family physicians identified as having serious practice deficiencies by the University of Manitoba's Clinical Assessment and Enhancement Program. DESIGN: Nonrandomized control trial in which data were collected from patients' charts and physician performance was evaluated. Differences in subjects' scores were tested at program entry and at 6 months and 18 months later using a two-way analysis of variance. SETTING: Family medicine practices in Manitoba. PARTICIPANTS: Fifteen family physicians: five study subjects and 10 control subjects. The five study subjects were identified as needing CME to improve their clinical performance. The 10 control subjects were randomly selected. INTERVENTIONS: Participants attended a 10-session, learner-centred, small group CME program. MAIN OUTCOME MEASURES: Clinical care, preventive care, charting, and the use of drugs were the variables assessed. RESULTS: Study subjects' initial scores were much lower than those of controls, but improved significantly during the CME program. CONCLUSION: A learner-centred, small group CME program can improve clinical performance.

Analysis of Variance↗
PubMed1993

Flexible fibreoptic sigmoidoscopy. Safe and effective for family practice.

Flexible fibreoptic sigmoidoscopy can detect malignancy, polyps, and other common diseases of the large bowel when they are distal to the splenic flexure. The procedure is safe and not painful when correctly performed. Family physicians could play an important role in the earlier diagnosis and prevention of colorectal cancer by adding the procedure to their repertoire.

Attitude of Health Personnel↗
PubMed1992

Primum non nocere.

Explore the source record for details and available documents.

Attitude to Health↗
PubMed1982

Enhancement of individual and community competence: the older adult as community worker.

This paper presents an evaluation of a primary prevention program designed to enhance individual and community competence in older adult community workers and in community residents with whom they worked. A total of 22 community workers and 97 community residents participated in the study; 30 residents constituted as posttest-only control group. Pre-post changes included increased knowledge of community services among all participants, as well as increased number of community information channels and increased life satisfaction for the workers. Residents, particularly black residents, became more internal, and their increased sense of personal control was related to their increased knowledge of services. Thus, the helper-therapy principle was supported for these older adult, mostly female, community workers, and their helping role had a net empowering effect.

Aged↗
PubMed1977

Retinal pigment epitheliitis.

Sixty-one patients with retinal pigment epitheliitis were studied. Fifty-two eyes in 40 patients were followed for 2 years. Good central visual acuity was maintained in more than 80% of these eyes. The differential diagnosis of retinal pigment epitheliitis and the characteristic findings are described.

Adult↗