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Biomedical subjects

J Cairney

Publications and source records attributed to J Cairney.

At least 19 recordsLinked to original sources
PubMed2005

Developmental coordination disorder and overweight and obesity in children aged 9-14 y.

Developmental coordination disorder (DCD) is a significant problem that affects between 5 and 9% of all children. Since children with DCD are less likely than their non-DCD peers to participate in physical activities, they may be at greater risk for overweight and obesity. In this report, we examine the relationship between DCD and overweight and obesity in a sample of 578 children aged 9-14 y. We also examine whether the relationship between DCD and overweight/obesity is the same for boys and girls, taking into account sex and age-appropriate differences in percentage body fat and body mass index (BMI) criteria. Our results show that for boys, DCD may be a risk factor for overweight/obesity in childhood and early adolescence. For girls, there is no difference in the prevalence of overweight/obesity between children with and without the disorder.

Adolescent↗
PubMed2003

Improving loblolly pine somatic embryo maturation: comparison of somatic and zygotic embryo morphology, germination, and gene expression.

Clonal production of loblolly pine ( Pinus taeda L.) through somatic embryogenesis has the potential to meet the increasing industrial demands for high-quality uniform raw materials. A major barrier to the commercialization of this technology is the low quality of the resulting embryos. Twenty-five newly initiated loblolly pine genotypes were followed through the process of liquid culture establishment, embryo maturation, germination, and retrieval from cryogenic storage. A maturation medium, capable of promoting the development of loblolly pine somatic embryos that can germinate, is presented that combines 1/2 P6 modified salts, 2% maltose, 13% polyethylene glycol 8000 (PEG), 5 mg/l abscisic acid (ABA), and 2.5 g/l Gelrite. A procedure for converting and acclimating germinants to growth in soil and greenhouse conditions is also described. A set of somatic seedlings, produced from the maturation medium, showed 100% survival when planted in a field setting. Somatic seedlings showed normal yearly growth relative to standard seedlings from natural seed. The quality of the resulting embryos was examined and compared to that of zygotic embryos using such parameters as morphology, dry weight, germination performance, and gene expression. All of the observations that were made support the conclusion that even with the new maturation medium somatic embryos grow approximately only halfway through the normal sequence of development and then prematurely discontinue growth.

Abscisic Acid↗
PubMed2001

An aquaglyceroporin is abundantly expressed early in the development of the suspensor and the embryo proper of loblolly pine.

In contrast to angiosperms, pines and other gymnosperms form well-developed suspensors in somatic embryogenic cultures. This creates a useful system to study suspensor biology. In a study of gene expression during the early stages of conifer embryogenesis, we identified a transcript, PtNIP1;1, that is abundant in immature loblolly pine (Pinus taeda) zygotic and somatic embryos, but is undetectable in later-stage embryos, megagametophytes, and roots, stems, and needles from 1 year-old seedlings. Analysis of PtNIP1;1 transcript in embryo proper and suspensor tissues by reverse transcription-polymerase chain reaction suggests preferential expression in the suspensor. Based on comparisons of derived amino acid sequences, PtNIP1;1 belongs to the nodulin-like members of the major intrinsic protein superfamily branch of the aquaporin (major intrinsic protein) superfamily. Through heterologous expression in Xenopus laevis oocytes and the yeast (Saccharomyces cerevisiae) fps1(-) mutant, PtNIP1;1 has been shown to be an active aquaglyceroporin.

Amino Acid Sequence↗
PubMed2000

Major depressive disorder and marital transition among mothers: results from a national panel study.

This analysis employs a national panel study to examine the relationship between marital transition and depression among mothers within the framework of selection and causation processes. The data come from the two-wave, longitudinal National Population Health Survey (NPHS) by Statistics Canada collected in 1994 and again in 1996 focusing on women between 20 and 65 years of age with children living at home (N = 2169). Compared with mothers who remain married, mothers making the transition into single-parenthood had a significantly higher rate of major depression at Time 1, which increased, but not significantly, at Time 2. This suggests that a selection effect may explain the elevated levels of depression among mothers experiencing a marital disruption. Rates of depression among single-parent mothers making the transition into a marital relationship did not decrease significantly between waves nor did the rate differ significantly from stable single-parent mothers at Time 1 or Time 2, suggesting that movement into marriage is not a protective factor.

Adult↗
PubMed2000

Abg1: a novel gene up-regulated by abscisic acid in guard cells of Vicia faba L.

A novel gene (abg1) was isolated by differential display RT-PCR from guard cells of Vicia faba L. Abg1 transcript accumulated in guard cells that were incubated with 5 microM S(+)-ABA for 1 h. The full-length abg1 cDNA was 753 bp, which included a 513 bp coding region. The deduced 17.8 kDa protein shared sequence similarity with several desiccation-related proteins reported in plants.

Abscisic Acid↗
PubMed2000

Focused ion beam in dental research.

Focused ion beam (FIB) has been available for over 10 yrs but until recently its usage has been confined to the semiconductor industry. It has been developed as an important tool in defect analysis, circuit modification and recently transmission electron microscope sample preparation. This paper introduces FIB and demonstrates its application in dental research. Its ion and electron imaging modes complement the SEM while its ability to prepare TEM samples from a wide range of material will allow the study of new types of adhesive interface. As an example, its use is described in the characterization of the interface of resin to a tribochemically treated surface of an experimental fiber-reinforced resin-based composite. As with all new techniques, the initial learning curve was difficult to manage. This new instrument offers opportunities to expand research in dental materials to areas not possible before.

Aluminum Oxide↗
PubMed1998

Correlates of body weight in the 1994 National Population Health Survey.

OBJECTIVE: This study examines three specific questions about obesity and overweight, using a nationally representative sample of Canadians. Are sociodemographic and lifestyle behaviors associated with body weight? Is body weight correlated with specific health outcomes? Has the prevalence of obesity in Canada changed since 1978? METHODS: Secondary data analysis of a cross-sectional survey. SAMPLE: This study uses the 1994 National Population Health Survey (NPHS) by Statistics Canada. It is a stratified random sample of 19600 Canadians across all provinces. RESULTS: The results show that age, gender, education, birth place and region, are significantly associated with obesity. When a lower criterion is used for overweight and obesity (body mass index, BMI > or = 25), dummy variables for marital status and occupation are also significant. Second, obesity is associated with poorer self-rated health, high blood pressure, heart disease, diabetes, arthritis, respiratory and stomach problems. For those respondents who have a BMI score of 25 or greater, there is also an association with stroke. Finally, it is unclear whether the prevalence of obesity has changed. However, there appears to be a systematic difference between studies using actual height and weight measurements (anthropometric) vs self-reported measurements. CONCLUSIONS: Weight can be considered a modifiable risk factor and reductions in the prevalence of obesity should reduce the risk of specific chronic conditions. Provincial variations in the prevalence of obesity (BMI > or = 27) and overweight and obesity (BMI > or = 25) suggest that collapsing provinces into regions may obscure important inter-provincial differences in body weight. More research is required to assess whether or not obesity is decreasing in Canada. Some of the limitations of self-reported data are discussed.

Adult↗
PubMed1996

Cloning of a cDNA for a chitinase homologue which lacks chitin-binding sites and is down-regulated by water stress and wounding.

A cDNA clone (pLP6) of a gene which is repressed under water deficit was isolated from a loblolly pine (Pinus taeda L.) cDNA library and characterized. The predicted polypeptide encoded by pLP6 bears strong resemblance to a number of Class I chitinases. However, LP6 lacks most of the amino-terminal and, consequently the signal peptide, cysteine-rich chitin-binding domain and glycine/proline-rich "hinge' region, diagnostic of Class I chitinases, are absent. Although the cDNA is similar in size to its mRNA, the long open reading frame encoding the LP6 protein commences halfway through the mRNA, implying a 5'-untranslated region of over 700 nucleotides. Subfragments from the 5' end of pLP6 hybridize to the same mRNA as do probes consisting of the entire cDNA. Reverse transcription(RT)-PCR experiments confirm that the cDNA derives from a single mRNA molecule. Analysis of the 5'-UTR revealed six upstream open reading frames and four inverted repeat structures. Expression of the pLP6 gene is repressed by water deficit stress and wounding. Possible functions and origin of this gene are discussed.

Amino Acid Sequence↗
PubMed1987

The osmotically regulated proU locus of Salmonella typhimurium encodes a periplasmic betaine-binding protein.

The proU locus of Salmonella typhimurium encodes an osmotically induced betaine transport system. We have identified a 31 kDa periplasmic protein, encoded by proU, whose synthesis is induced by osmotic stress. A specific betaine-binding activity with a KD of about 1 microM is also present in the periplasm of osmotically induced cells. This activity is absent in those proU mutants which lack the 31 kDa periplasmic protein. Thus, ProU is a periplasmic binding-protein-dependent transport system.

Bacterial Proteins↗
PubMed1986

Osmotic regulation of transcription: induction of the proU betaine transport gene is dependent on accumulation of intracellular potassium.

The proU locus, which encodes a high-affinity betaine transport system, and the kdp operon, which encodes a potassium transport system, are the principal osmoresponsive genes in Escherichia coli and Salmonella typhimurium. The kdp operon is known to be induced in response to changes in cell turgor. We have investigated the control of proU expression and shown that it differs from that of kdp in a number of fundamental ways. Rather than responding to changes in turgor, proU expression is principally determined by the intracellular accumulation of potassium ions. Potassium and betaine were shown to play distinct osmoprotective roles. Potassium serves as the principal osmoprotectant and is accumulated in response to low-level osmotic stress to restore turgor. As external osmolarity is increased to a level at which the corresponding increase in internal potassium concentrations is potentially deleterious to enzyme function, betaine (when available) is accumulated in preference to potassium. The different mechanisms of proU and kdp regulation reflect the different physiological roles of these two osmoprotectants.

Betaine↗
PubMed1985

Salmonella typhimurium proP gene encodes a transport system for the osmoprotectant betaine.

Betaine (N,N,N-trimethylglycine) can be accumulated to high intracellular concentrations and serves an important osmoprotective function in enteric bacteria. We found that the proP gene of Salmonella typhimurium, originally identified as encoding a minor transport system for proline (permease PP-II), plays an important role in betaine uptake. Mutations in proP reduced the ability of betaine to serve as an osmoprotectant. Transport of betaine into the cells was also severely impaired in these mutants. The kinetics of uptake via PP-II suggest that betaine, rather than proline, is the important physiological substrate for this transport system. Betaine uptake via PP-II was regulated by osmotic pressure at two different levels: transcription of the proP gene was increased by increasing osmolarity, and, in addition, activity of the transport system itself was dependent upon the osmotic pressure of the medium. The specificity of the transport system was also altered by increasing osmolarity which enhanced the affinity for betaine while reducing that for proline.

Amino Acid Transport Systems, Neutral↗
PubMed1985

Osmoregulation of gene expression in Salmonella typhimurium: proU encodes an osmotically induced betaine transport system.

Previous evidence has indicated that a gene, proU, is involved in the response of bacterial cells to growth at high osmolarity. Using Mu-mediated lacZ operon fusions we found that transcription of the proU gene of Salmonella typhimurium is stimulated over 100-fold in response to increases in external osmolarity. Our evidence suggests that changes in turgor pressure are responsible for these alterations in gene expression. Expression of proU is independent of the ompR gene, known to be involved in osmoregulation of porin expression. Thus, there must be at least two distinct mechanisms by which external osmolarity can influence gene expression. We show that there are relatively few genes in the cell which are under such osmotic control. The proU gene is shown to encode a high-affinity transport system (Km = 1.3 microM) for the osmoprotectant betaine, which is accumulated to high concentrations in response to osmotic stress. Even when fully induced, this transport system is only able to function in medium of high osmolarity. Thus, betaine transport is regulated by osmotic pressure at two levels: the induction of expression and by modulation of activity of the transport proteins. We have previously shown that the proP gene encodes a lower-affinity betaine transport system (J. Cairney, I. R. Booth, and C. F. Higgins, J. Bacteriol., 164:1218-1223, 1985). In proP proU strains, no saturable betaine uptake could be detected although there was a low-level nonsaturable component at high substrate concentrations. Thus, S. typhimurium has two genetically distinct pathways for betaine uptake, a constitutive low-affinity system (proP) and an osmotically induced high-affinity system (proU).

Betaine↗