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Biomedical subjects

J Mackenzie

Publications and source records attributed to J Mackenzie.

At least 19 recordsLinked to original sources
PubMed1998

Repeatability of the hand-held Nidek auto-keratometer in children.

Measurement of the anterior corneal radius of curvature is important in the pediatric population for proper fitting of contact lenses, calculation of intraocular lens power in patients undergoing cataract surgery, and monitoring changes in shape of the cornea in keratoconus. Because astigmatism in preschool children is mainly the result of corneal asphericity, measurement of the anterior corneal radius of curvature may also be used in screening in children at risk for amblyopia. The aim of this study was to determine the repeatability of the hand-held automated Nidek keratometer (Nidek Co. Ltd, Tokyo, Japan) and its ease of use in children.

Adolescent↗
PubMed1997

Isolation of Japanese encephalitis virus from Culex annulirostris in Australia.

Mosquitoes were collected using CO2 and octenol-baited light traps during an outbreak of Japanese encephalitis (JE) on Badu Island in the Torres Strait, Australia in April 1995. A total of 13,300 mosquitoes comprising 12 species were processed for virus isolation. Eight isolates of JE virus were obtained from Culex annulirostris, with a carriage rate of 2.97:1,000; this mosquito also yielded one Sindbis virus isolate. A reverse transcriptase-polymerase chain reaction was used to sequence the JE viruses, which were compared with published sequences. The eight isolates were 90% homologous with known JE strains but only 68% homologous with other flaviviruses. Among the isolates, 99% homology was obtained, suggesting a common point of origin.

Aedes↗
PubMed1997

'A thorny problem for feminism': an analysis of the subjective work experiences of enrolled nurses.

Feminist methodology has been used in this study to investigate the subjective work experiences of 19 enrolled nurses. Reflexive conversational techniques enabled participants to relate autobiographical narratives examining their experiences of working in a nursing hierarchy. Two themes are reported: 'nursing identity' and 'exploitation'. Through an analysis of these themes insight has been gained into the manner in which nurses inter-relate. The study demonstrates how the correlation between rank, status and expertise within the nursing hierarchy may have negative consequences for patient care.

Adult↗
PubMed1996

Characterization of a novel influenza hemagglutinin, H15: criteria for determination of influenza A subtypes.

Two viruses with a novel hemagglutinin (HA), A/duck/Australia/341/83 and A/shearwater/West Australia/2576/79, have been isolated from a duck and a shorebird in Australia. Hemagglutination inhibition and double immunodiffusion assays failed to reveal cross-reactivity with any of the known subtypes (H1 to H14). We therefore propose that these viruses constitute a new HA subtype, H15. Sequence analysis of the HA genes confirmed the serologic findings. When compared at the amino acid level, the HA1 region of the H15 subtype differs from those of the other subtypes by 30% and more. This degree of heterogeneity is also found among HA genes of other subtypes. Thus we propose that amino acid sequence data should be evaluated when determining the HA subtypes of influenza A viruses. Sequence comparison and phylogenetic analysis suggested that the HA subtype H15 is most closely related to the H7. Compared to the H7 HA, the H15 acquired a 30-nucleotide insertion within HA1 at position 253 which is located in the globular head of the molecule. This finding suggests that RNA recombination, although a rare event in nature, may play an important role in the evolution of influenza viruses.

Amino Acid Sequence↗
PubMed1996

Zinc and calcium apparent absorption from an infant cereal: a stable isotope study in healthy infants.

Fractional apparent absorption of Zn and Ca from a wheat-milk-based infant cereal was studied in six healthy infants (18-30 weeks old). Mineral absorption was measured by a stable-isotope technique based on faecal excretion of the isotopes. Each test meal (40 g cereal) was extrinsically labelled with 70Zn and 42Ca before intake. All faecal material passed during the 21 d following intake of the labelled test meal was collected on trace-element-free nappies. Individual stool samples were analysed for their content of 70Zn and 42Ca by thermal ionization mass spectrometry. Apparent absorption was calculated as intake minus total faecal excretion of the isotopes over 68-92 h after administration. The fractional apparent absorption values for Zn and Ca were 33.9 (SD 16.4) % (range 19.2-63.9%) and 53.5 (SD 12.6) % (range 36.7-71.7%) respectively. Re-excretion of absorbed 70Zn (> 68-92 h to 21 d after intake of the labelled meal) was 0.44 (SD 0.38) % of administered dose while only one infant re-excreted detectable amounts of 42Ca (1.74% of administered dose). The analysis of individual stool samples confirmed that 72 h is a sufficient time period for complete collections of non-absorbed isotopes in faecal material from infants during the weaning period and that re-excretion of initially absorbed 70Zn and 42Ca (> 68-92 h to 21 d after intake of the labelled meal) is negligible.

Calcium↗
PubMed1996

Dietary fiber in weaning cereals: a study of the effect on stool characteristics and absorption of energy, nitrogen, and minerals in healthy infants.

We evaluated the effect of increased dietary fiber (DF) content in weaning cereals based on wheat/soy (8.0 and 1.8% DF) and wheat/milk (5.3 and 2.0% DF) in healthy, formula-fed infants 7-17 weeks old. The study had a cross-over design, each infant acting as his or her own control. Stool characteristics and anthropometry were monitored over 4-week periods in groups of 34 (wheat/soy) and 23 (wheat/milk) infants. Absorption of zinc (Zn) and calcium (Ca) was studied by measuring the fecal excretion of stable isotopes during 72 h (70Zn and 42Ca) in a subgroup of the infants consuming wheat/soy cereals. Iron (Fe) bioavailability was evaluated by analysis of the incorporation of 58Fe into erythrocytes 14 days after administration. Fractional absorption (X +/- SD: 8.0 versus 1.8% DF) was 45.3 +/- 27.5 versus 41.2 +/- 19.4% of 70Zn and 63.4 +/- 15.8 versus 64.4 +/- 10.6% of 42Ca. Bioavailability of 58Fe varied between 1.0% and 5.4% (8.0% DF) and from <0.9% to 9.1% (1.8% DF). No significant difference in energy (95.3 +/- 2.0% versus 95.7 +/- 1.2%) or nitrogen (92.6 +/- 2.3% versus 93.0 +/- 1.6%) apparent absorption from the total diet was found during consumption of cereal with 8.0 and 1.8% DF. The intake of cereal decreased with higher DF content in the wheat/soy product: 34 +/- 23 g/d (8.0% DF) versus 42 +/- 23 g/d (1.8% DF), p < 0.01. While consuming the 8.0% DF product, 11 infants were reported to have "gritty stools"; no other differences were observed between different groups in stool characteristics or anthropometry. These results demonstrate no negative effect on the absorption of energy and nutrients with higher dietary fiber intake in primarily formula-fed infants. The impact of increased dietary fiber levels remains unknown in less well-nourished infants.

Aging↗
PubMed1995

Gynopia in nursing practice: the case of urethral catheterization.

A pilot study of catheterized women was designed to investigate their perceptions of pain and discomfort during the procedure. The study aimed to test the feasibility of conducting a larger randomized controlled trial. Problems were encountered during the execution of the study, due to the need to conform to established principles in clinical research. Restrictions on access to patients impinged upon the opportunity to 'cast the net wide' in order to generate meaningful data.

Attitude to Health↗
PubMed1994

A comparison study of the EF-18 agar/Hydrophobic Grid Membrane Filter (HGMF) method and the enzyme linked antibody (ELA)/HGMF method to the HPB standard method in the isolation of Salmonella.

As part of a comparative and collaborative study of rapid methods for the detection of Salmonella and the standard Health Protection Branch (HPB) method, six Federal and Provincial Laboratories compared the EF-18 agar/Hydrophobic Grid Membrane Filters (HGMF) method to the standard HPB method. Two Federal Laboratories also compared the enzyme linked antibody (ELA)/HGMF method (which is a further development of the EF-18 agar/HGMF method) to the standard method. During this study the false-negative rates ranged from 0% to 15% for the standard HPB method, from 5.88% to 43.5% for the EF-18 agar/HGMF method, and from 0% to 10.5% for the ELA/HGMF method. The EF-18 agar/HGMF method did not compare well with the standard HPB method due to the number of false-negatives. Problems with this method resulted from the inability to isolate colonies of Salmonella on the HGMF due to the small colony size, abnormal colony coloration, and overgrowth by competitors. The ELA/HGMF method, however, was shown to be comparable to the standard HPB method. The main advantages of this method are that the antibody-staining step is independent of colony coloration and carbohydrate utilization on the plating media; the ability to detect some unusual strains of Salmonella irrespective of their atypical reactions on the media; and the ELA staining can indicate the presence of Salmonella even when the HGMF is overgrown by competitors. Also, cultural confirmation can proceed simultaneously yet independently of the ELA staining procedure. The data presented here indicate that this method is worth further study.

Bacteriological Techniques↗
PubMed1994

Aortic valvuloplasty: an alternative for aortic insufficiency.

The authors describe a technique for aortic valve repair in patients with aortic regurgitation with excellent intermediate term results avoiding the complications of prosthetic valve replacement. Conservation of native valve tissue will obviate complications associated with prosthetic valves.

Aortic Valve↗
PubMed1993

Protein kinase C activity during the process of lung liquid clearance.

Although active transport of sodium plays an important role in the resolution of pulmonary edema, the biochemical regulation of this process is still under investigation. The purpose of this study was to evaluate the activity of protein kinase C during the process of lung liquid clearance. Alveolar flooding was induced by instilling 5% bovine serum albumin solution, saline, or heterologous serum in the air spaces of rats. The activity of protein kinase C was measured in both the instilled and control lungs at 10 min and 1 and 4 h after fluid instillation. Four hours after instillation of 5% bovine serum albumin, the ratio of protein kinase C activity in the instilled lung compared with the control lung was 2.2 +/- 0.3. Similar results were obtained following instillation with heterologous serum or saline. Since we measured a clearance rate of 0.8 ml/h in anesthetized rats, we can postulate that the activation of protein kinase C occurred when > 40% of the liquid had been cleared from the lung. This increased activity of protein kinase C was not due to an increase in kinase activity in the inflammatory cells or an increase in enzyme quantity but due to a decrease of protein kinase C inhibitory activity in the lung. These results suggest that protein kinase C second messenger system may play a regulatory role in lung liquid clearance.

Animals↗