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Biomedical subjects

J MacGregor

Publications and source records attributed to J MacGregor.

At least 19 recordsLinked to original sources
PubMed1999

Enhanced expression of P-selectin (CD62P) by endothelial cells seeded onto synthetic arterial prostheses (PET, Dacron) is correlated with leukocyte interactions.

This study evaluated the expression by seeded endothelial cells (S-EC) of P-selectin (CD62P/GMP-140/PADGEM), an adhesion molecule implicated in endothelial-leukocyte interactions. Endothelial cells were seeded onto knitted polyethylene terephthalate (PET, Dacron(R)) prostheses and compared with control endothelial cells (C-EC) cultured in flasks to the same stage. Using flow cytometry techniques, we observed that CD62P expression by PET S-EC was significantly increased (p<0.05) compared to C-EC. Moreover, RT PCR techniques showed that the CD62P RNA level was higher on S-ECs compared to C-ECs. Following adhesion assays, increased polymorphonuclear neutrophil (PMN) attachment to the PET-seeded prostheses as compared to control cultures (p<0.001) was observed. PMN adherence was enhanced by TNFalpha activation. PMN adhesion was decreased significantly (p<0.001) after the incubation of resting EC or TNFalpha-activated EC-seeded prostheses with a blocking monoclonal antibody (LYP20) directed against the P-selectin. Such results suggest that: (1) PET prosthetic material may induce the expression of P-selectin by S-EC; (2) seeding conditions provoke an increase in PMN adhesion; (3) increased PMN interactions with seeded PET material is partially dependent upon P-selectin expression by the S-EC.

Animals↗
PubMed1999

Selectin and Lewis(x) are required as co-receptors in antibody-dependent cell-mediated cytotoxicity of human eosinophils to Schistosoma mansoni schistosomula.

Killing of Schistosoma mansoni larvae by human eosinophils via antibody-dependent cell-mediated cytotoxicity (ADCC) mechanisms requires adherence between effector cells and parasite targets. The role of adhesion molecules in this mechanism was investigated using blocking monoclonal antibodies (mAb) and soluble ligands. We show that, along with the Mac-1 alpha chain, interactions between selectins and LewisX-related structures, both expressed by eosinophils and parasite targets, play a critical part in the antibody-dependent cytotoxic function of eosinophils. To further elucidate the interactions between adhesion molecules and eosinophil Fc receptors, ADCC was performed with IgG1 or IgA mAb. We found that mAb directed against Mac-1 alpha chain or against LewisX could significantly inhibit the IgG1-, but not IgA cytotoxicity. This result might be explained, at least in part, by the inhibitory effect of these mAb on the release by eosinophils of eosinophil cationic protein, one of the major mediators involved in target killing. Taken together, these results suggest novel interactions between Fc receptors and selectins and LewisX-related structures which might act as co-receptors for eosinophil-mediated cytotoxicity.

Animals↗
PubMed1998

Charting the course of change.

Change and transition are different concepts. Transition for practitioners in the workplace is complex. Transition within roles needs a positive tripartite arrangement with teacher and clinical manager. This paper looks at the findings from a study of 100 enrolled nurses undertaking a part-time conversion programme to RGN, RMN or RSCN. Evidence suggests that student perceptions change over time within a 2-year programme. This conversion programme is seen as a positive experience by participants and employers.

Adaptation, Psychological↗
PubMed1997

Opening up the options: making the inflexible into a flexible framework.

The post-registration framework for registered nurses and midwives was set up to provide flexible continuing education programmes for registered nurses. For those students who already have the basic professional qualification specific to their area of practice, professional development programmes are intended as a vehicle for improving their own personal professional competence. However, for those individuals who wish to gain further qualification or to change from one practice context to another, it is argued that the framework does not adequately address their needs. At present, pre-registration diplomates emerge from the Project 2000 programme with a qualification which enables them to work in one specific area of practice only. This early specialization is not in line with current and projected USA and European thinking (Castledine 1995) and may lead to a reduction in the broad base of nursing knowledge. It is further argued that pre-registration programmes should provide a generic base of nursing theory and practice, whereas specialist knowledge and practice should be the main thrust of post-registration work. The authors argue that initial development of nurses in specialist areas at pre-registration level restricts their ability to respond to rapidly changing health care needs later in their careers. The post-registration framework should be a flexible vehicle by which individuals can gain expanded knowledge in a particular field of practice or can change professional direction if they wish. Thus, nurses would have the freedom to develop in a way that is most appropriate to their changing individual needs.

Education, Nursing, Baccalaureate↗
PubMed1996

Orientation to higher education: the challenges and rewards.

A new 'starter' course for qualified nurses entering higher education is discussed in this article. The background and aims of this course, which enables traditionally trained nurses to enter a pathway of professional and academic development, are presented. Learning outcomes of the course, identified through a formal evaluation procedure, were categorized into product and process components. Course teachers anticipated that the product outcomes would be evaluated most highly but the participants reported that the process outcomes were more important to them. They believed these process outcomes would empower them not only to undertake further academic studies but also to take a greater part in clinical decision-making. The results of this evaluation demonstrate that for many nurses, who seek to launch themselves into higher education, a 'bridging' programme is necessary to support this transition.

Career Mobility↗
PubMed1996

The potential role of insulin-like growth factors in skeletal muscle regeneration.

The role of the insulin-like growth factors I and II (IGF-I and IGF-II), previously known as the somatomedins, in general growth and development of various tissues have been known for many years. Thought of exclusively as endocrine factors produced by the liver, and under the control of growth hormone, the somatomedins were known as the intermediaries by which growth hormone exerted its cellular effects during tissue growth and maturation. Eventually it was discovered that virtually every tissue type is capable of autocrine production of the IGFs, and their involvement in skeletal muscle tissue repair and regeneration became apparent. Recent advances in technology have allowed the characterisation of many of the different growth factors believed to play a role in muscle regeneration, and experimental manipulations of cells in culture have provided insight into the effects of the various growth factors on the myoblast. This paper explores the potential role of the IGFs in skeletal muscle regeneration. A critical role of IGF-II in terminal differentiation of proliferating muscle precurser cells following injury is proposed.

Animals↗
PubMed1996

Converting the image.

Explore the source record for details and available documents.

Education, Nursing, Baccalaureate↗
PubMed1994

Rolling and stationary cytoadhesion of red blood cells parasitized by Plasmodium falciparum: separate roles for ICAM-1, CD36 and thrombospondin.

Adhesion of parasitized erythrocytes to microvascular endothelium is a central event in the pathogenesis of severe falciparum malaria. We have characterized the adhesion of flowing parasitized red blood cells to three of the known endothelial receptors coated on plastic surfaces (CD36, intercellular adhesion molecule-1 (ICAM-1) and thrombospondin (TSP)), and also to cells bearing these receptors (human umbilical vein endothelial cells (HUVEC) and platelets). All of the surfaces could mediate adhesion at wall shear stress within the physiological range. The great majority of adherent parasitized cells formed rolling rather than static attachments to HUVEC and ICAM-1, whereas static attachments predominated for platelets, CD36 and TSP. Studies with monoclonal antibodies verified that binding the HUVEC was mainly via ICAM-1, and to platelets via CD36. Adhesion via ICAM-1 was least sensitive to increasing wall shear stress, but absolute efficiency of adhesion was greatest for CD36, followed by ICAM-1, and least for TSP. TSP did not give long-lasting adhesion under flow, whereas cells remained adherent to CD36 or ICAM-1. We propose that the different receptors may have complementary roles in modulating adhesion in microvessels. Initial interaction at high wall shear stress may be of a rolling type, mediated by ICAM-1 or other receptors, with immobilization and stabilization occurring via CD36 and/or TSP.

Animals↗
PubMed1983

Paucity of morphological changes in the brains of ageing beagle dogs: further evidence that Alzheimer lesions are unique for primate central nervous system.

Twelve regions of grey matter from the brains of 25 Beagle dogs, varying from one to over 16 years in age, were serially sectioned and sequentially scanned with a semi-automated sampling stage microscope, in a morphometric search for neuritic plaques, neurofibrillary tangles, and evidence of nerve cell loss. Examination of 227,776 light microscopic fields failed to reveal any senile plaques or neurofibrillary tangles. The neuronal densities, which ranged from 473 to 37,014 nucleolated neurons/mm3, showed no significant relationship with ageing. Neuronal lesions of Alzheimer type may be more typical of the human CNS; and physiological evidence for regionally reduced glucose metabolic rate in this animal model may require other structural alterations for its explanation.

Aging↗
PubMed1983

The physiological cost of gait (PCG): a new technique for evaluating nonsteroidal anti-inflammatory drugs in rheumatoid arthritis.

The physiological cost of gait (PCG) provides a technique for reproducibly quantifying the physical disabilities occasioned by inflammatory joint disease. The preferred walking speed (PWS) and the physiological cost index (PCI) related to achieving that PWS are shown to be abnormal in rheumatoid arthritis (RA) and objective improvement can be demonstrated with naproxen and indomethacin, two commonly-used nonsteroidal anti-inflammatory drugs (NSAIDs). Twenty patients with active RA were studied by double-blind cross-over technique and 16 completed the two-month study. Reliable PCG data obtained in 13 patients showed statistically significant improvement in PWS and PCI with NSAID therapy. Improvement was not correlated with conventional clinical measures of joint inflammation such as pain score, articular index, haemoglobin or ESR but the trends were similar. PCG may offer a reproducible, objective method of quantifying disability and response to treatment.

Arthritis, Rheumatoid↗
PubMed1982

An infra-red reflectance system for ambulatory characterization of left ventricular function.

An optical method of detecting the arterial pulse is described. The system employs an infra-red light emitting diode (LED) and phototransistor arranged to operate in the reflectance mode and sited over the superficial temporal artery. The LED is pulsed and the signal recovery system performs a synchronous sample-and-hold function on the phototransistor output. This arrangement improves peak light output relative to ambient light and extends battery life. The transducer, used at its site of application over the temporal artery produces an arterial pulse-wave relatively resistant to motion artefact, and is thus suitable for ambulatory monitoring applications. The pulsewave can be used to obtain measurements of left ventricular ejection time with the accuracy required for clinical systolic time interval investigations.

Ambulatory Care↗
PubMed1981

Phospholipase A activity in supernatants from cultures of Bacteroides melaninogenicus.

The phospholipase A activity in culture supernatants of two strains of Bacteroides melaninogenicus is described. The enzyme utilize phosphatidylcholine as substrate and produce mainly lysophosphatidylcholine and free fatty acids. The activities are Ca2+-independent, are not affected by the presence of a chelating agent, have a broad pH range (5-9) and an optimum temperature for activity of approx. 50 degrees C. The activity in a growing bacterial culture increases from the end of the lag phase to the late exponential phase of growth. Analysis of the products resulting from the actions of the enzymes on L-alpha-palmitoyl-beta-oleoyl[1-14C]phosphatidylcholine indicates that the enzymes are phospholipase A1 (EC 3.1.1.32).

Bacteroides↗
PubMed1980

Long-term ambulatory physiological surveillance equiment (LAPSE).

A system is described for the acquisition of physiological data for up to 24-hour periods in the ambulant subject free to undertake his usual daily activities. ECG and trunk acceleration signals are recorded on a small analogue magnetic tape recorder along with a stable time-reference. The standard C120 tape cassette used in the recorder is replayed at 60 times the recording speed and the recovered data automatically processed to yield outputs which describe the instantaneous heart rate response of the subject to particular activity. The system is evaluated and the potential indicated by examples of clinical application.

Activities of Daily Living↗