Biomedical subjects

M J Harrison

Publications and source records attributed to M J Harrison.

At least 55 records · Page 3Linked to original sources

PubMed1999

The assessment of postmortem brain volume; a comparison of stereological and planimetric methodologies.

We compared two methods of estimating the volume of 10 formalin-fixed brains using MRI. MRI was performed and total brain volume was then assessed using two distinct techniques: a stereological point-counting technique based on the Cavalieri principle, and an edge-tracing technique. The total brain volumes obtained using these two techniques were similar and correlated closely with each other (r = 0.97). Both methods could be optimised to a similar degree while maintaining the coefficient of error at an acceptably low level. However, the stereological assessment of brain volume required between 20 min and 30 min per brain, depending on the number of points per sampling grid, compared with 1 h per brain using the planimetric method. Thus, while planimetric and stereological approaches yield very similar results, the stereological method has the advantage of greater speed and, therefore, efficiency.

Aged↗

PubMed1999

Formative evaluation of a collaborative community-based child abuse prevention project.

OBJECTIVE: Together for Kids is a child abuse prevention project that serves children and families in two neighboring communities in a mid-sized Canadian city. The project, a collaborative endeavor of various agencies in the health, social services, and law enforcement sectors, focuses on preventing child abuse and neglect through family support and programming. This article presents the results of a formative evaluation of the project focusing on client and team member views on project implementation. METHOD: The evaluation strategy was primarily qualitative. In-person interviews following a semi-structured format were conducted with 17 clients and 10 team members by an external evaluator. In addition a review of all client records was conducted. RESULTS: The community-based approach, the multidisciplinary composition of the team, the ability to seek services when needed, the immediacy of the response time and the availability of support during stressful times were all aspects of the project that clients found beneficial. The most beneficial aspect of the project, however, was the informal support received from team members who were accepting, non-threatening, and non-judgmental. Team members found the collaborative approach made access to services easier for clients, particularly for those who were more socially isolated. CONCLUSIONS: Multidisciplinary, community-based models of service delivery contribute to a more effective and compassionate response to vulnerable families. Attention to the variables identified as important aspects of the project from the clients' perspective in this evaluation may assist others in developing similar programs.

Adolescent↗

PubMed1999

Fathers' scores on the Nursing Child Assessment Teaching Scale: are they different from those of mothers?

Fathers of 103 Canadian infants (ages 2 to 12 months) were observed interacting with their child using the Nursing Child Assessment Teaching Scale (NCATS). Compared with the NCATS reference data for 387 mothers of similar-aged infants with similar marital status and ethnic background, there was no significant difference on the overall total score. However, fathers had significantly lower scores than mothers on the total parent score. Infants interacting with the fathers had significantly higher total child scores than those interacting with the mothers. Although mothers and fathers were equally sensitive to their infant's cues, fathers were less contingent in interaction with their infants. Implications for practitioners are discussed.

Adult↗

PubMed1999

Diagnostic monitoring in anaesthesia using fuzzy trend templates for matching temporal patterns.

A technique based on the concept of a 'fuzzy trend template' has been developed to identify characteristic patterns in multiple time-series. The method has its foundation in fuzzy logic and allows for the intuitive and transparent description of 'templates', which preserve nuances of vagueness, temporal relationships and quantitative descriptors. Evaluation of fuzzy trend templates can provide both belief and plausibility information for use in diagnostic applications. The technique has been applied to the diagnosis of specific problems in anaesthesia and has demonstrated sensitivity and specificity of 95 and 65%, respectively. Evaluation of fuzzy trend templates is, computationally, relatively efficient and has allowed a real-time implementation. The technique has the potential to be useful in any domain that requires temporal pattern recognition based on linguistic rules.

Anesthesia↗

PubMed1999

Personality traits of anaesthetists and physicians: an evaluation using the Cloninger Temperament and Character Inventory (TCI-125).

The personality profiles of Specialist Anaesthetists, Trainee Anaesthetists and Specialist Physicians were examined using Cloninger's Temperament and Character Inventory. These were compared with validated Community Sample 'average values' and a historical Norwegian Physician sample. Completed forms were returned from 364 doctors (Specialist Anaesthetists 222, Trainee Anaesthetists 75, Physicians 67), an overall response rate of 71%. Specialist Anaesthetists were more Cooperative, Harm Avoidant and Self-Directed than the Community Sample but less Reward Dependent, Novelty Seeking and Persistent than the Community Sample. Physicians were more Cooperative than their Specialist Anaesthetist colleagues, but both more so than were the general population. Trainee anaesthetists appear to be more Novelty Seeking and Reward Dependent than the Specialist Anaesthetists, this factor being predominately age related. Extreme/Mild personality traits were identified in 33% of Specialists, 41% of Trainees and 33% of Physicians, whilst personality disorders were found at the expected rates (Specialist Anaesthetists 9%, Trainee Anaesthetists 10%, Physicians 2%). Personality assessment has implications for recruitment, crisis management and professional development within anaesthesia.

Adult↗

PubMed1999

Novel genes induced during an arbuscular mycorrhizal (AM) symbiosis formed between Medicago truncatula and Glomus versiforme.

Many terrestrial plant species are able to form symbiotic associations with arbuscular mycorrhizal fungi. Here we have identified three cDNA clones representing genes whose expression is induced during the arbuscular mycorrhizal symbiosis formed between Medicago truncatula and an arbuscular mycorrhizal fungus, Glomus versiforme. The three clones represent M. truncatula genes and encode novel proteins: a xyloglucan endotransglycosylase-related protein, a putative arabinogalactan protein (AGP), and a putative homologue of the mammalian p110 subunit of initiation factor 3 (eIF3). These genes show little or no expression in M. truncatula roots prior to formation of the symbiosis and are significantly induced following colonization by G. versiforme. The genes are not induced in roots in response to increases in phosphate. This suggests that induction of expression during the symbiosis is due to the interaction with the fungus and is not a secondary effect of improved phosphate nutrition. In situ hybridization revealed that the putative AGP is expressed specifically in cortical cells containing arbuscules. The identification of two mycorrhiza-induced genes encoding proteins predicted to be involved in cell wall structure is consistent with previous electron microscopy data that indicated major alterations in the extracellular matrix of the cortical cells following colonization by mycorrhizal fungi.

Amino Acid Sequence↗

PubMed1999

The down-regulation of Mt4-like genes by phosphate fertilization occurs systemically and involves phosphate translocation to the shoots.

Mt4 is a cDNA representing a phosphate-starvation-inducible gene from Medicago truncatula that is down-regulated in roots in response to inorganic phosphate (Pi) fertilization and colonization by arbuscular mycorrhizal fungi. Split-root experiments revealed that the expression of the Mt4 gene in M. truncatula roots is down-regulated systemically by both Pi fertilization and colonization by arbuscular mycorrhizal fungi. A comparison of Pi levels in these tissues suggested that this systemic down-regulation is not caused by Pi accumulation. Using a 30-bp region of the Mt4 gene as a probe, Pi-starvation-inducible Mt4-like genes were detected in Arabidopsis and soybean (Glycine max L.), but not in corn (Zea mays L.). Analysis of the expression of the Mt4-like Arabidopsis gene, At4, in wild-type Arabidopsis and pho1, a mutant unable to load Pi into the xylem, suggests that Pi must first be translocated to the shoot for down-regulation to occur. The data from the pho1 and split-root studies are consistent with the presence of a translocatable shoot factor responsible for mediating the systemic down-regulation of Mt4-like genes in roots.

Amino Acid Sequence↗

PubMed1999

Transient ischaemic attacks related to carotid stenosis precipitated by straining, bending, and sneezing.

Three patients are described in whom one or more carotid territory transient ischaemic attacks (TIAs) were preceded by sneezing, straining, or bending over. It is argued that the mechanism involved dislodgment of embolic material from the site of carotid atheroma. This mechanism should be considered as an alternative to paradoxical embolism when TIAs are precipitated by such physiological manoeuvres. Furthermore, TIAs should be added to the list of medical hazards associated with such events.

Carotid Stenosis↗

PubMed1999

Parent-child interactions and development of toddlers born preterm.

Fathers and mothers of 49 healthy preterm and 54 full-term infants were observed interacting with their child at 3 and 12 months using the Nursing Child Assessment Teaching Scale. Each parent completed the Parenting Stress Index at both times. At 18 months adjusted age, the children were assessed using the Bayley Scales of Infant Development, Sequenced Inventory of Communication Development-Revised, and MacArthur Communicative Development Inventory. Preterm children scored significantly lower on the Bayley Mental scale and on the number of words produced. Early parent-child interactions contributed to the child's development. Mother's interactions with the child, child gender, and family socioeconomic status predicted 17% of the variance in the Bayley Mental score. Mother's and father's interactions with the child, child gender, and the child's behavior with his or her mother predicted 22% of the variance in receptive communication skills.

Adult↗

PubMed1999

Computer-enhanced diagnosis of malignant hyperpyrexia.

A computer program using fuzzy logic templates has been developed to enhance the diagnosis of malignant hyperpyrexia. When tested, retrospectively, against the physiological changes that occurred during the onset of a bona fide malignant hyperpyrexia episode it made the diagnosis about 10 minutes before the anaesthetist. When tested against the changes associated with laparoscopic surgery, which has certain similarities, the diagnosis of malignant hyperpyrexia was very transient. The use of this program may assist the anaesthetist in the diagnosis of this rare event.

Algorithms↗

PubMed1998

Characterization of the Mt4 gene from Medicago truncatula.

Previously we identified Mt4, a phosphate starvation inducible cDNA from Medicago truncatula which is down-regulated in roots in response to phosphate fertilization as well as colonization by arbuscular mycorrhizal (AM) fungi (AM). Here we present further studies of Mt4. Expression was highly sensitive to exogenous applications of phosphate fertilizer; transcripts were abundant in roots fertilized with nutrient solution lacking phosphate, reduced when fertilized with 0.02 or 0.1 mM phosphate and undetectable when fertilized with 1 or 5 mM phosphate. A time course experiment, to study the expression of Mt4 following colonization by AM fungi, revealed that Mt4 transcripts increased in uncolonized roots during the first three weeks of growth and then plateaued, while transcript levels in roots colonized with the AM fungus, Glomas versiforme, increased transiently and then decreased. Although the Mt4 gene is expressed exclusively in roots, transcripts were also detected in M. truncatula cell suspension cultures following phosphate starvation. A genomic clone containing the Mt4 gene and 1133 bp of the 5' flanking sequence was identified from a M. truncatula genomic library. The promoter region contains a conserved cis-element found in the promoters of phosphate starvation inducible genes of yeast and tomato. As Mt4 is the first cDNA reported to show independent regulation by both phosphate and mycorrhizal fungi, the genomic clone may provide a starting point from which to analyze the signal transduction pathways involved in these two processes.

Base Sequence↗

PubMed1998

Modified glycosylation of cellobiohydrolase I from a high cellulase-producing mutant strain of Trichoderma reesei.

Cellobiohydrolase I is an industrially important exocellulase secreted in high yields by the filamentous fungus Trichoderma reesei. The nature and effect of glycosylation of CBHI and other cellulolytic enzymes is largely unknown, although many other structural and mechanistic aspects of cellulolytic enzymes are well characterised. Using a combination of liquid chromatography, electrospray mass spectrometry, solid-phase Edman degradation, and monosaccharide analysis we have identified every site of glycosylation of CBHI from a high cellulase-producing mutant strain of T. reesei, ALKO2877, and characterised each site in terms of its modifying carbohydrate and site-specific heterogeneity. The catalytic core domain comprises three N-linked glycans which each consist of a single N-acetylglucosamine residue. Within the glycopeptide linker domain, all eight threonines are variably glycosylated with between at least one, and up to three, mannose residues per site. All serines in this domain are at least partially glycosylated with a single mannose residue. This linker region has also been shown to be sulfated by a combination of ion chromatography and collision-induced dissociation electrospray mass spectrometry. The sulfate is probably mannose-linked. The biological significance of N-linked single N-acetylglucosamine in the catalytic core, and mannose sulfation in the linker region, is not known.

Acetylglucosamine↗

PubMed1998

Glycobiology and proteomics: is mass spectrometry the Holy Grail?

One characteristic of glycoproteins is that they are separated by two-dimensional electrophoresis (2-D PAGE) into typical 'trains' of protein spots which separate on the basis of different isoelectric point (pI) and/or molecular mass. The pattern of these trains often varies in development and disease. While the isoforms differ both in the number of sites of glycosylation and the types of carbohydrate attached to the protein, classical methods of glycan analysis are insensitive at the levels typically separated by 2-D PAGE. Developments in mass spectrometry technologies have enabled the characterization of most of the oligosaccharide attributes to be determined on picomole amounts of protein. These techniques are beginning to allow the glycoform heterogeneity on 2-D separated glycoproteins to be analyzed.

Amino Acid Sequence↗

PubMed1998

Central pontine myelinolysis in AIDS.

Central pontine myelinolysis (CPM) is an uncommon complication in sick patients with severe underlying disorders such as chronic alcoholism, malignancy, malnutrition and hyponatraemia. We report two patients with advanced HIV infection who developed CPM. In one case the diagnosis was not suspected in life, in the other the diagnosis was made just before death, on the basis of magnetic resonance (MR) imaging appearances. At post mortem there was a close correlation between the MR abnormalities and the anatomic changes in the pons.

Acquired Immunodeficiency Syndrome↗

PubMed1998

Development of the arbuscular mycorrhizal symbiosis.

The arbuscular mycorrhizal (AM) symbiosis formed between plant roots and fungi is one of the most widespread symbiotic associations found in plants, yet our understanding of events underlying its development are limited. The recent integration of biochemical, molecular and genetic approaches into analyses of the symbiosis is providing new insights into various aspects of its development. In the past year there have been advances in our understanding of the signals required for the formation of appressoria, the molecular changes in the root in response to colonisation, and components of the signal transduction pathways common to both the AM and Rhizobium symbioses.

Fabaceae↗

PubMed1998

Elevated cerebrospinal fluid and serum nitrate and nitrite levels in patients with central nervous system complications of HIV-1 infection: a correlation with blood-brain-barrier dysfunction.

As nitric oxide (.NO) is hypothesised to play a role in the immunopathogenesis of neurological complications associated with inflammation, we compared levels of cerebrospinal fluid (CSF) and serum .NO metabolites in 24 patients with HIV-1 infection, to those in 58 non-HIV infected patients with neurological disorders. Levels of .NO metabolites were correlated with blood-brain-barrier dysfunction. CSF and serum nitrate and nitrite levels were measured by the nitrate reductase and Griess reaction methods. The .NO metabolites, nitrate and nitrite, were raised in the CSF and serum of patients with AIDS and central nervous system complications, when compared to non-HIV infected patients with inflammatory and non-inflammatory neurological disorders (median nitrate and nitrite: CSF=18.3 microM vs. 11.1 microM vs. 7.0 microM, P<0.001, and serum=53.8 microM vs. 50.3 microM vs. 41.4 microM, P=0.04, respectively). CSF nitrate and nitrite levels correlated with the albumin quotient. This study supports the evidence that .NO is a potential mediator of blood-brain-barrier breakdown in inflammatory diseases of the central nervous system.

Acquired Immunodeficiency Syndrome↗

PubMed1998

Prediction of the mechanisms of enzyme-catalysed reactions using hybrid quantum mechanical/molecular mechanical methods.

The use of hybrid methods, involving both quantum mechanics and molecular mechanics, to model the mechanism of enzyme-catalysed reactions, is discussed. Two alternative approaches to treating the electrostatic interactions between the quantum mechanical and molecular mechanical regions are studied, involving either the inclusion of this term in the electronic Hamiltonian (QM/MM), or evaluating it purely classically (MO + MM). In the latter scheme, possible problems of using force fields that are standard for macromolecular modelling are identified. The use of QM/MM schemes to investigate the mechanism of the enzymes thymidine phosphorylase (ThdPase) and protein tyrosine phosphatase (PTP) is described. For both systems, transition states have been identified using a PM3 Hamiltonian. For ThdPase, concerted motion of the enzyme during the course of the reaction is suggested and, for PTP, a two-step dephosphorylation reaction is indicated, both with quite low barriers.

Catalysis↗

PubMed1998

Men as caregivers: reciprocal relationships or obligation?

This study explored reciprocity in the relationships of men caregivers of cognitively impaired older adults. Reciprocity is a dimension of social support that is important in caregivers' ability to sustain supportive relationships. Equity theory predicts that inequitable (non-reciprocal) exchanges will result in termination of relationships. The objective of the study was to identify the context in which reciprocity was present or absent, the characteristics of reciprocity in caregivers' relationships with the care recipient, family and friends, and the men's feelings about reciprocal social support during caregiving. Twenty-two men caregivers were interviewed three times over 18 months. Study findings were confirmed in a focus group discussion with seven caregivers. Three variations in reciprocity in the men's relationship with the care recipient were identified: waived reciprocity, generalized reciprocity and constructed reciprocity. Those experiencing constructed or generalized reciprocity described positive feelings, whereas men identifying waived reciprocity described either positive or negative feelings. When reciprocity was absent the men described giving care on the basis of obligation with either mixed or negative feelings. Reciprocity in relationships with friends and family is also described. The study findings support the assumptions of equity theory about reciprocity; however, perceptions of obligation may be better understood in the context of the principles of justice and caring.

Adult↗