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Biomedical subjects

A McLennan

Publications and source records attributed to A McLennan.

12 recordsLinked to original sources
PubMed2001

Similarities not differences: an exploration of the impact of change upon a group of nursing lecturers within a university setting.

The concepts of collaboration and partnership currently have extensive impact upon health care providers and higher education institutions. One of the challenges is to develop networks which will foster partnerships able to react, and contribute, to an ever-evolving educational culture. These themes are illustrated by using the example of one school of nursing and midwifery, and the collective experience of a number of its academic staff. By focusing on distinct features of collaboration (strategic planning, origins of change, group dynamics and building a community), the authors seek to explore the impact of an educational culture in an attempt to provide meaning to their recent experiences. In so doing, group identity is explored and the prospect for creating partnerships across disciplines ('similarities rather than differences') is considered.

Faculty, Nursing↗
PubMed1999

Ap4A induces apoptosis in human cultured cells.

Diadenosine oligophosphates (Ap(n)A) have been proposed as intracellular and extracellular signaling molecules in animal cells. The ratio of diadenosine 5',5'''-P1,P3-triphosphate to diadenosine 5',5'''-P1,P4-tetraphosphate (Ap3A/Ap4A) is sensitive to the cellular status and alters when cultured cells undergo differentiation or are treated with interferons. In cells undergoing apoptosis induced by DNA topoisomerase II inhibitor VP16, the concentration of Ap3A decreases significantly while that of Ap4A increases. Here, we have examined the effects of exogenously added Ap3A and Ap4A on apoptosis and morphological differentiation. Penetration of Ap(n)A into cells was achieved by cold shock. Ap4A at 10 microM induced programmed cell death in human HL60, U937 and Jurkat cells and mouse VMRO cells and this effect appeared to require Ap4A breakdown as hydrolysis-resistant analogues of Ap4A were inactive. On its own, Ap3A induced neither apoptosis nor cell differentiation but did display strong synergism with the protein kinase C activators 12-deoxyphorbol-13-O-phenylacetate and 12-deoxyphorbol-13-O-phenylacetate-20-acetate in inducing differentiation of HL60 cells. We propose that Ap4A and Ap3A are physiological antagonists in determination of the cellular status: Ap4A induces apoptosis whereas Ap3A is a co-inductor of differentiation. In both cases, the mechanism of signal transduction remains unknown.

3T3 Cells↗
PubMed1998

Protection against solar ultraviolet radiation.

Interest in protection against solar ultraviolet radiation (UVR) among the general public in Australia has been increasing steadily as a result of the 'SunSmart' campaigns run by the various state cancer councils. This increasing awareness is due in part to the requirements for occupational protection of outdoor workers and to provision of UVR protection for the recreational market. Behaviour outdoors can significantly affect exposure to solar UVR and use of items of personal protection can provide a substantial reduction in the UVR dose received. The protective properties of sunscreens, sunglasses, hats and clothing against UVR have been the subject of considerable research for some time, and over the last few years interest has extended to the provision of shade structures and the UVR protection provided by various commonly used materials. These materials include shadecloth, plastics, glass, windscreens and applicable tints. Australia has rigorous standards covering protection and UVR, in particular for sunscreens [Standards Australia/Standards New Zealand, Sunscreen products-evaluation and classification, Report No. AS 2604, Sydney/Wellington, 1993.], sunglasses [Standards Australia, Sunglasses and fashion spectacles-nonprescription types, Report No. AS 1067.1, Sydney, 1990.], protective eyewear [Standards Australia/Standards New Zealand, Eye protectors for industrial applications, Report No. AS/NZS 1337, Sydney/Wellington, 1992.] and shadecloth [Standards Australia, Synthetic shadecloth, Report No. AS 4174, Sydney, 1994.]. Compliance with the sunglass standard became mandatory in 1988 and UVR protection provided by sunglasses has increased substantially since then. In July 1996 a standard on 'sun protective textiles' [Standards Australia/Standards New Zealand, Sun protective clothing-evaluation and classification, Report No. AS/NZS 4399, Sydney, 1996.] incorporating ultraviolet protection factors (UPFs) and a rating scheme with protection categories, was introduced; this was the first of its kind in the world. Australian Radiation Laboratory (ARL) UPF swing tags with UVR protection advice from the Australian Cancer Society on the reverse side are used to denote the amount of protection against solar UVR provided by clothing. To date in excess of 5 million ARL swing tags have been issued. Work on the various standards is continuing. The maximum allowed 'sun protection factor' (SPF) limit for sunscreens may be increased to SPF 30 + in the near future, and additions to the sun protective textiles standard are also planned. This paper discusses measurement methods, results, the rationale used in formulating the Australian Standards and the current state of UVR protection in Australia.

Australia↗
PubMed1997

Fetal hemoglobin changes in the twin oligohydramnios-polyhydramnios sequence.

Fetal hemoglobin concentration was measured in each twin from five monochorionic pregnancies complicated by twin-to-twin transfusion, diagnosed by growth discordance and coexistent oligohydramnios-polyhydramnios. In three cases the hemoglobin concentration of the smaller twin with oligohydramnios was lower than the normal mean for gestation, and the hemoglobin difference was more than 5 g/dl in two of these cases. In the other two cases, the hemoglobin concentration of the four fetuses with coexistent oligohydramnios-polyhydramnios was within the normal range. This suggests that twin-to-twin transfusion may occur without hemoglobin changes, or that alternatively coexistent oligohydramnios-polyhydramnios occurs in the absence of twin-to-twin transfusion.

Female↗
PubMed1997

UV protection by clothing: an intercomparison of measurements and methods.

In an attempt to reduce the incidence of skin cancer, cancer foundations have run educational campaigns which encourage the general population to limit their solar UVR exposures. An important part of these campaigns, in particular in Australia, but also more recently in Europe and the U.S., has been the adoption of protective measures such as sunscreens, hats, sunglasses and clothing. The protective properties of fabrics and clothing against ultraviolet radiation (UVR) have been known for some time, but recently there has been considerable interest in quantifying the degree of protection. This has been generated, in part, by the requirements for occupational protection for outdoor workers as well as the provision of UVR protection for the recreational market. The quantification of UVR protection has been laboratory based using in vitro test methods. Development of a standard test method has become an important part of the testing process, and this paper presents results from an intercomparison involving five independent testing laboratories. Agreement is good, in particular for samples with protection factors below 50. Technical difficulties and sources of errors associated with the measurements are discussed.

Australia↗
PubMed1996

Evaluation of three-dimensional ultrasonography and magnetic resonance imaging in assessment of congenital heart anomalies in fetal cardiac specimens.

In this observational study, multiplanar three-dimensional ultrasound images were reconstructed from tomographic views obtained by scanning seven cadavaric fetal hearts with various congenital heart defects. Comparisons were made with multiplanar three-dimensional magnetic resonance imaging (MRI) of the hearts. Good-quality echocardiographic images were obtained in all but one of the fetal hearts. Multiplanar as well as three-dimensional reconstructions were possible and allowed accurate assessment of complex cardiac defects. Overall, the MRI projections had better image quality and revealed more structural details than the sonographic views, although both imaging modes showed the same cardiac anatomical abnormalities. Our initial results demonstrate that simultaneous multiplanar display of cross-sectional echocardiographic views can be performed to provide three-dimensional images of the fetal heart, demonstrating structural cardiac malformation. However, the clinical application of three-dimensional fetal echocardiography is at present limited by the time required for image data acquisition and the need for accurate temporal and positional gating in the living fetus.

Autopsy↗
PubMed1996

A new lethal chondrodysplasia with platyspondyly, long bone angulation and mixed bone density.

A fetus diagnosed by sonography at 20 weeks' gestation had multiple skeletal abnormalities. The main features were absent ossification of the skull and cervical and upper thoracic vertebral bodies; short, angulated femora, tibiae, radii and ulnae but normal humeri; platyspondyly; trident-shaped acetabular roofs; sclerotic bands on the iliac wings and scapulae; clavicular hooks; and overall, mixed bone density. We suggest that this is a new chondrodysplasia which, since the parents are first cousins, could follow autosomal recessive inheritance.

Abnormalities, Multiple↗
PubMed1990

Bacteraemia following incision and drainage of dento-alveolar abscesses.

Twenty-five patients undergoing routine incision and drainage of dento-alveolar abscesses were screened for bacteraemia during the procedure. In 13 patients, the abscesses were aspirated with a needle prior to incision and drainage, while needle aspiration was omitted in the remaining 12. A blood sample was taken from all individuals immediately before the surgical procedures and at one-minute intervals for a period of 5 minutes after surgery. Needle aspiration of pus resulted in a significant reduction (P less than 0.05) in the bacteraemic episodes (0 out of 13) during subsequent surgery as compared with incision and drainage, without aspiration (3 out of 12). Bacteraemia appeared to be transient, although in one case it was detected at 5 minutes. It is concluded that bacteraemic episodes occur during incision and drainage of dento-alveolar abscesses and this may be reduced by aspiration of the abscess contents prior to incision and drainage. In addition, the aspirates could serve as excellent microbiological samples, uncontaminated with salivary flora. The need for antibiotic cover in at risk patients, however, needs to be established by further studies.

Bacteria↗