Biomedical subjects
M Atkinson
Publications and source records attributed to M Atkinson.
Food photography II: use of food photographs for estimating portion size and the nutrient content of meals.
The aim of the present study was to determine the errors in the conceptualization of portion size using photographs. Male and female volunteers aged 18-90 years (n 136) from a wide variety of social and occupational backgrounds completed 602 assessments of portion size in relation to food photographs. Subjects served themselves between four and six foods at one meal (breakfast, lunch or dinner). Portion sizes were weighed by the investigators at the time of serving, and any waste was weighed at the end of the meal. Within 5 min of the end of the meal, subjects were shown photographs depicting each of the foods just consumed. For each food there were eight photographs showing portion sizes in equal increments from the 5th to the 95th centile of the distribution of portion weights observed in The Dietary and Nutritional Survey of British Adults (Gregory et al. 1990). Subjects were asked to indicate on a visual analogue scale the size of the portion consumed in relation to the eight photographs. The nutrient contents of meals were estimated from food composition tables. There were large variations in the estimation of portion sizes from photographs. Butter and margarine portion sizes tended to be substantially overestimated. In general, small portion sizes tended to be overestimated, and large portion sizes underestimated. Older subjects overestimated portion size more often than younger subjects. Excluding butter and margarine, the nutrient content of meals based on estimated portion sizes was on average within +/- 7% of the nutrient content based on the amounts consumed, except for vitamin C (21% overestimate), and for subjects over 65 years (15-20% overestimate for energy and fat). In subjects whose BMI was less than 25 kg/m2, the energy and fat contents of meals calculated from food composition tables and based on estimated portion size (excluding butter and margarine) were 5-10% greater than the nutrient content calculated using actual portion size, but for those with BMI 30 kg/m2 or over, the calculated energy and fat contents were underestimated by 2-5%. The correlation of the nutrient content of meals based on actual or estimated portion sizes ranged from 0-84 to 0-96. For energy and eight nutrients, between 69 and 89% subjects were correctly classified into thirds of the distribution of intake using estimated portion size compared with intakes based on actual portion sizes. When 'average' portion sizes (the average weight of each of the foods which the subjects had served themselves) were used in place of the estimates based on photographs, the number of subjects correctly classified fell to between 60 and 79%. We report for the first time the error associated with conceptualization and the nutrient content of meals when using photographs to estimate food portion size. We conclude that photographs depicting a range of portion sizes are a useful aid to the estimation of portion size. Misclassification of subjects according to their nutrient intake from one meal is reduced when photographs are used to estimate portion size, compared with the use of average portions. Age, sex, BMI and portion size are all potentially important confounders when estimating food consumption or nutrient intake using photographs.
Stromelysin-3 (ST-3) mRNA expression in colorectal carcinomas. Localization and clinicopathologic correlations.
Stromelysin-3 (ST-3) mRNA expression was studied in 28 colorectal carcinomas and compared with that of adjacent nontumorous tissue. By Northern blot analysis, levels of ST-3 mRNA were significantly increased in the carcinomas compared with ST-3 expression was seen with degree of invasion, nodal or distant metastases, or histologic grade. In situ hybridization of nontumorous tissue showed no significant ST-3 expression. In tumor tissue, ST-3 mRNA was localized adjacent to colon carcinoma cells in irregular foci within the stoma. No significant difference in ST-3 expression was found between the center and periphery of the colon tumors. Most of the colon carcinomas (26 of 28) induced an expression of ST-3 in the directly adjacent stroma. No significant correlation between ST-3 mRNA expression and tumor stage and grade was seen. By Northern blot, we also saw expression of ST-3 in noncarcinomatous tissue, further supporting the concept that ST-3 expression is a tumor-induced but not a tumor-specific phenomenon.
Research training and productivity among faculty: the Canadian Association of Professors of Psychiatry and the Canadian Psychiatric Association Survey.
OBJECTIVE: This survey assesses the research training and productivity of academic faculty in Canadian departments of psychiatry and compares the findings with those of colleagues in the United States. METHOD: A questionnaire was adapted to suit the Canadian milieu and was distributed to a target population of 2484, including a core 522 full-time faculty. RESULTS: The response rate among full-time faculty was 65%, but only 26.5% for clinical and adjunct faculty. A small proportion (16%) of our MD and a greater proportion (57%) of our PhD respondents were included in a fairly lenient definition of researcher. Departments seek to recruit PhDs with an active involvement in research. Overall there appear to be more similarities than differences in research interests with our colleagues in the United States. The pharmaceutical industry was the most frequently mentioned source of research funding for MDs, while the availability of a mentor was perceived as the most influential factor determining the choice of a research career. CONCLUSIONS: Recommendations include adequate exposure to research during medical school and residency as well as appropriate inducements for the recruitment and retention of practising researchers.
Physician resource variables and their impact on the future pool of research expertise among psychiatrists: the Canadian Association of Professors of Psychiatry and Canadian Psychiatric Association Survey.
OBJECTIVE: To assess the impact of the increased proportion of female psychiatrists and trainees, the rapid reduction of international medical graduates allowed in the country, and the expanding number of practitioners with subspecialization on the future pool of psychiatrist researchers in Canadian academic departments of psychiatry. METHOD: A questionnaire was adapted to suit the Canadian milieu and distributed to a target population of 2484, including a core of 522 full-time faculty. RESULTS: Female psychiatrists responding to the questionnaire reported less research involvement overall than their male counterparts. International medical graduates with both undergraduate and residency training abroad reported more research interests than other graduate categories. Respondents training in a subspecialty showed no difference in research commitment. CONCLUSIONS: Concerted efforts must be made to recruit, support, and retain female researchers. Particular attention must be paid to developing research expertise among Canadian medical graduates. The trend towards subspecialization influences only the selection of research topic.
AIDS knowledge and high-risk behaviour in the chronic mentally ill.
OBJECTIVE: To ascertain the degree of HIV-risk knowledge among patients attending a downtown program and to identify the extent of high-risk behaviour for HIV infection. METHOD: A total of 151 patients were selected at the Calgary Community Mental Health Clinic (N = 110) and the nearby Self Help Association (N = 41). Most of the subjects were being treated for either schizophrenia (n = 69), bipolar disorder (n = 37), or unipolar mood disorder (n = 35). Questionnaires included a 10-item instrument that assessed subjects' knowledge about HIV or AIDS and another 10-item tool that assessed the high-risk situations patients might have encountered over the past month or past year. RESULTS: Although the percentage of subjects erring on questions about AIDS knowledge was smaller when compared with previous studies, a significant number of subjects believed that one could acquire AIDS by donating blood, and 25% did not think that having only one unsafe sexual contact would make them vulnerable to HIV infection. At least 50% of the participants have had sex with at least one partner in the past year, and 33% of the participants indicated that they would not insist that they or their partners wear a condom. CONCLUSIONS: This Canadian study confirms the need for psychiatrists and mental health workers to continue to explore high-risk behaviour in the chronic mentally ill population and to further educate these patients through the development of prevention and risk-reduction strategies.
Research productivity among PhD faculty members and affiliates responding to the Canadian Association of Professors of Psychiatry and Canadian Psychiatric Association survey.
OBJECTIVE: This survey endeavours to assess the research productivity of PhD degree holders affiliated with Canadian academic departments of psychiatry. METHOD: A questionnaire was adapted to suit the Canadian milieu and was distributed to a target population of 2484, of whom 345 were nonmedical PhDs. RESULTS: Out of 861 respondents, 148 indicated that they held a PhD degree only--a response rate of 42.9% for that subgroup. PhD respondents engaged in significantly more research activities than MDs. Their fields of research activity differed according to amount of time spent in research activities. Few gender differences were observed. CONCLUSIONS: The recruitment of sole PhD holders is an indicator of the current research needs of departments and of the dearth of candidates for these positions among MDs.
Cardiac coherence: a new, noninvasive measure of autonomic nervous system order.
Although cardiac sympathovagal regulation has been studied during stress using power spectral density analysis of heart rate variability, little is known about its regulation during emotional states. Using heart rate variability measurements, we studied autonomic balance in 20 subjects trained in a mental and emotional self-management technique called Freeze-Frame. The study was conducted in two environments: under controlled laboratory conditions, and under real-life stressful conditions in the workplace. Power spectral density plots of R-R intervals obtained from electrocardiogram recordings were divided into three regions: low frequency (predominantly sympathetic activity), midfrequency, and high frequency (parasympathetic activity). Measurements were taken for a 5-minute baseline period, followed by a 5-minute period of positive emotional expression. Three unique conditions of autonomic nervous system order can be clearly discriminated in the data: (1) normal heart function mode, (2) entrainment mode, and (3) internal coherence mode. The internal coherence mode is new to the electrophysiology literature. We provide supporting data for modes 2 and 3 and show that a group of 20 subjects trained in this technique can enter and maintain these states at will. We found that, when one is in the entrainment mode, other physiological systems lock to the entrainment frequency, which is approximately 0.1 Hz. The results suggest that emotional experiences play a role in determining sympathovagal balance independent of heart rate and respiration and further suggest that positive emotions lead to alterations in heart rate variability that may be beneficial in the treatment of hypertension and reduce the likelihood of sudden death in patients with congestive heart failure and coronary artery disease.
Amplified expression and large-scale purification of protein L'.
The gene fragment (PPL') encoding the functional unit of peptostreptococcus protein L was isolated using PCR and expressed in E. coli. As the gene fragment lacked its own promoter, the 5' PCR primer was designed to incorporate an Nde1 restriction site (CATATG) into the gene. This enabled the gene to be cloned in frame into an Nde1 restriction site immediately downstream of a trp promoter. To prevent read through, a stop codon was introduced into the 3' primer. Expression of PPL' was up to 27% total cell protein which compares favourably to the 0.1% total soluble cell protein obtained from the original clone of peptostreptococcus. Following a heat step homogeneous PPL' was recovered by a single anion-exchange chromatography step on Q-Sepharose FF in yields of 90%.
The effects of emotions on short-term power spectrum analysis of heart rate variability .
In summary, this work extends previous findings by demonstrating that anger produces a sympathetically dominated power spectrum, whereas appreciation produces a power spectral shift toward MF and HF activity. Results suggest that positive emotions lead to alterations in HRV, which may be beneficial in the treatment of hypertension and in reducing the likelihood of sudden death in patients with congestive heart failure and coronary artery disease.
Substitutions of aspartic acid for glycine-220 and of arginine for glycine-664 in the triple helix of the pro alpha 1(I) chain of type I procollagen produce lethal osteogenesis imperfecta and disrupt the ability of collagen fibrils to incorporate crystalline hydroxyapatite.
We identified two infants with lethal (type II) osteogenesis imperfecta (OI) who were heterozygous for mutations in the COL1A1 gene that resulted in substitutions of aspartic acid for glycine at position 220 and arginine for glycine at position 664 in the product of one COL1A1 allele in each individual. In normal age- and site-matched bone, approximately 70% (by number) of the collagen fibrils were encrusted with plate-like crystallites of hydroxyapatite. In contrast, approximately 5% (by number) of the collagen fibrils in the probands' bone contained crystallites. In contrast with normal bone, the c-axes of hydroxyapatite crystallites were sometimes poorly aligned with the long axis of fibrils obtained from OI bone. Chemical analysis showed that the OI samples contained normal amounts of calcium. The probands' bone samples contained type I collagen, overmodified type I collagen and elevated levels of type III and V collagens. On the basis of biochemical and morphological data, the fibrils in the OI samples were co-polymers of normal and mutant collagen. The results are consistent with a model of fibril mineralization in which the presence of abnormal type I collagen prevents normal collagen in the same fibril from incorporating hydroxyapatite crystallites.
Identification of genes specifically expressed at discrete stages of B-cell development.
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Molecular mapping of wheat: major genes and rearrangements in homoeologous groups 4, 5, and 7.
A molecular-marker linkage map of hexaploid wheat (Triticum aestivum L. em. Thell) provides a framework for integration with teh classical genetic map and a record of the chromosomal rearrangements involved in the evolution of this crop species. We have constructed restriction fragment length polymorphism (RFLP) maps of the A-, B-, and D-genome chromosomes of homoeologous groups 4, 5, and 7 of wheat using 114 F7 lines from a synthetic X cultivated wheat cross and clones from 10 DNA libraries. Chromosomal breakpoints for known ancestral reciprocal translocations involving these chromosomes and for a known pericentric inversion on chromosome 4A were localized by linkage and aneuploid analysis. Known genes mapped include the major vernalization genes Vrn1 and Vrn3 on chromosome arms 5AL and 5DL, the red-coleoptile gene Rc1 on 7AS, and presumptively the leaf-rust (Puccinia recondita f.sp. tritici) resistance gene Lr34 on 7DS and the kernel-hardness gene Ha on 5DS. RFLP markers previously obtained for powdery-mildew (Blumeria graminis f.sp. tritici) resistance genes Pm2 and Pm1 were localized on chromosome arms 5DS and 7AL.
Alkaline gastro-oesophageal reflux: dual probe pH monitoring.
Although the aetiology of Barrett's oesophagus or columnar line oesophagus (CLO), remains unknown, bile reflux has been implicated as a factor in its pathogenesis. This study aimed to detect alkaline reflux in gastro-oesophageal reflux patients using dual probe pH monitoring. Thirty patients with histologically diagnosed CLO, 15 age and sex matched patients with oesophagitis (grade 1-3), and 15 healthy volunteers were studied by dual probe, 18 hour pH monitoring and analysis of the bile acid content of oesophageal refluxate. Total acid exposure and acid exposure in the upright and supine postures were greater in CLO subjects than in oesophagitis patients and controls. Furthermore, the number of reflux episodes lasting more than five minutes and the duration of the longest reflux episode were significantly greater in the CLO subjects than the oesophagitis and control subjects. Nine subjects with CLO and oesophagitis, however, were not identified as refluxers, although six had a bile acid concentration in their oesophageal aspirate higher than the 95th centile value of the controls. There was no correlation between the oesophageal pH and the bile acid contents of refluxate. It is concluded that dual probe pH monitoring is not useful in detecting alkaline refluxers. pH monitoring, although the only subjective test available to identify acid refluxers, is not a sufficiently sensitive test with which to define alkaline reflux.
Cloning, expression and purification of Ppl-1, a kappa-chain binding protein, based upon protein L from Peptostreptococcus magnus.
Protein L is a multi-domain, cell wall constituent of certain strains of Peptostreptococcus magnus, which binds to the variable domain of the L-chains of Ig. A gene fragment which codes for a single Ig-binding domain of protein L (Ppl-1) was cloned into a modified pKK223-3 vector and over-expressed in E. coli JM103. A rapid protein purification protocol is described. In these studies, purified Ppl-1 was immobilised on to an agarose gel and tested against an array of Igs and Ig fragments. It was found that Ppl-1-bound Igs from a number of different sources via interactions with the L kappa-chain. An enzyme linked immunosorbant assay has been developed to assay the binding of Ppl-1 to IgG. The incubation of Ppl-1 with human serum does not produce an immunoprecipitate, thus suggesting one unique interaction per binding domain which has been confirmed by ELISA. These experiments demonstrate the potential value of Ppl-1 as an immunological tool and as an affinity chromatography ligand for the purification of Igs.
GAD65 autoantibodies increase the predictability but not the sensitivity of islet cell and insulin autoantibodies for developing insulin dependent diabetes mellitus.
The clinical onset of insulin-dependent diabetes (IDD) can be predicted by determination of autoantibodies to several pancreatic-islet cell antigens. Islet-cell autoantibodies (ICA) and insulin autoantibodies (AA) are most commonly used. We have developed a recombinant human glutamic acid decarboxylase (GAD65) radioimmunoassay and measured autoantibodies to GAD65 (GAD65A) in the sera of 73 documented prediabetic individuals, 76 newly-diagnosed patients, 103 relatives of IDD probands at increased risk for the development of IDD because they were positive for ICA and/or IAA, 72 ICA and IAA negative relatives, and 207 healthy controls. Our data demonstrate that GAD65A are strongly associated with the currently established autoantibody markers of IDD. Their presence in prediabetic subjects with only ICA or IAA enhances their risk for progression to IDD, yet does not much enhance the screening sensitivity already available through conventional ICA and IAA for IDD prediction.
Food photography. I: The perception of food portion size from photographs.
Fifty-one male and female volunteers aged 18-90 years from a wide variety of social and occupational backgrounds completed 7284 assessments of portion size in relation to food photographs. Subjects were shown six portion sizes (two small, two medium and two large) for each of six foods, and asked to compare the amount on the plate in front of them to (a) a series of eight photographs showing weights of portions from the 5th to the 95th centile of portion size (British Adult Dietary Survey), or (b) a single photograph of the average (median) portion size. Photographs were prepared either in colour or in black and white, and in two different sizes. The order of presentation of foods; use of black and white or colour; the size of photographs; and presentation of eight or average photographs were each randomized independently. On average, the mean differences between the portion size presented and the estimate of portion size using the photographs varied from -8 to +6 g (-4 to +5%) for the series of eight photographs, and from -34 to -1 g (-23 to +9%) for the single average photograph. Large portion sizes tended to be underestimated more than medium or small portion sizes, especially when using the average photograph (from -79 to -14 g, -37 to -13%). Being female, 65 years and over, or retired, or seeing photographs in colour, were all associated with small but statistically significant overestimations of portion size. Having a body mass index > or = 30 kg/m2 was associated with an 8% underestimate of portion size. We conclude that use of a series of eight photographs is associated with relatively small errors in portion size perception, whereas use of an average photograph is consistently associated with substantial underestimation across a variety of foods.