PubMed Health⌕ Search

Biomedical subjects

K Peterson

Publications and source records attributed to K Peterson.

At least 19 recordsLinked to original sources
PubMed2006

Preschool children's eating behaviours are related to dietary adequacy and body weight.

OBJECTIVE: The aim of this paper is to analyse the relationships between eating behaviours (picky eating, irregular eating and overeating), and dietary adequacy in accordance with nutrition recommendations and body weight during the preschool years. DESIGN AND SETTING: Our analyses were performed using data from the Longitudinal Study of Child Development in Québec (1998-2002), a population-based birth cohort. SUBJECTS: The study followed a representative sample (n=2103) of children born in 1998 in the Canadian province of Québec. METHODS: Eating behaviours were derived from self-administered questionnaires when children were 2.5, 3.5 and 4.5 years. Nutrition data were collected from one 24-hour recall interview conducted at home by trained nutritionists at 4.5 years. Children's weight and height were measured at 4.5 years. Statistical analyses were carried out with SAS (version 8.2). Weighted data adjusted for within-variability were used in the analysis, and the significance level was set at 5%. RESULTS: Picky eaters consume fewer total fats, less energy and less protein than children never reporting picky eating behaviours. Picky eaters were more likely to consume less than dietary recommendations for fruit and vegetables, and meat and alternatives. Overeaters consumed more total energy and more of each macronutrient than children who were never reported as overeaters during the preschool years. These children consumed more servings of grain products and meats and alternatives per day than children not classified as overeaters. Even when the number of servings of grain products consumed was similar for overeaters and children who were never overeaters, overeaters had higher body mass index. CONCLUSION: Given that children as young as 4.5 years are displaying some form of problematic eating behaviour which is shown to be related to dietary adequacy and body weight, public health professionals should be targeting parents of young children to provide messages about strategies for coping with problematic eating behaviours in early childhood.

Body Mass Index↗
PubMed2006

Microscopic and flow cytometric semen assessment of Dutch AI-bucks: effect of semen processing procedures and their correlation to fertility.

This study was done to determine the effects of processing techniques on the quality of semen from Dutch AI-bucks with the view on improving pregnancy rates after artificial insemination (AI) with liquid or frozen-thawed semen. Motility of spermatozoa was estimated under a microscope whereas the percentage live spermatozoa and the percentage live spermatozoa with intact acrosomes were determined by means of flow cytometry. Aspects of semen processing that were investigated are storage temperature of liquid semen (i), the effect of glycerol on liquid-stored semen (ii), removal of seminal plasma (iii) and type of extender (iv). The correlation between semen quality and fertility rates in inseminated does was also investigated. The percentage motile spermatozoa in semen stored in liquid form for 72 h progressively declined over time, irrespective of whether storage occurred at 4 or 18 degrees C. The percentage motile spermatozoa in semen stored at 18 degrees C was similar to that in semen stored at 4 degrees C if stored for 24 h but lower if stored for 48 h. Goats differ in the sensitivity of their spermatozoa to the deleterious effects of glycerol. Neither the removal of seminal plasma nor the type of extender had any effect on semen quality before freezing but semen frozen in a Tris-citric acid-glucose (TCG) buffer with egg yolk without removal of the seminal plasma had better quality after thawing than semen frozen in another diluent or after removal of seminal plasma. Remarkably no significant correlation between fertility and membrane integrity of spermatozoa could be found. Thus, although integrity assays for spermatozoa are useful to asses resistance to semen handling, the validity of these assays for predicting fertility is questioned.

Animals↗
PubMed2005

Reducing workload in systematic review preparation using automated citation classification.

OBJECTIVE: To determine whether automated classification of document citations can be useful in reducing the time spent by experts reviewing journal articles for inclusion in updating systematic reviews of drug class efficacy for treatment of disease. DESIGN: A test collection was built using the annotated reference files from 15 systematic drug class reviews. A voting perceptron-based automated citation classification system was constructed to classify each article as containing high-quality, drug class-specific evidence or not. Cross-validation experiments were performed to evaluate performance. MEASUREMENTS: Precision, recall, and F-measure were evaluated at a range of sample weightings. Work saved over sampling at 95% recall was used as the measure of value to the review process. RESULTS: A reduction in the number of articles needing manual review was found for 11 of the 15 drug review topics studied. For three of the topics, the reduction was 50% or greater. CONCLUSION: Automated document citation classification could be a useful tool in maintaining systematic reviews of the efficacy of drug therapy. Further work is needed to refine the classification system and determine the best manner to integrate the system into the production of systematic reviews.

Artificial Intelligence↗
PubMed2005

Application of Bruchin B to pea pods results in the up-regulation of CYP93C18, a putative isoflavone synthase gene, and an increase in the level of pisatin, an isoflavone phytoalexin.

Bruchins, mono and bis (3-hydroxypropanoate) esters of long chain alpha,omega-diols, are a recently discovered class of insect elicitors that stimulate cell division and neoplasm formation when applied to pods of peas and certain other legumes. Differential display analysis resulted in the identification of an mRNA whose level was increased by the application of Bruchin B to pea pods. The corresponding amplification product was cloned and sequenced and a full length cDNA sequence was obtained. This cDNA and the gene from which it was derived were assigned the name CYP93C18 based upon sequence similarities to the cytochrome P450 mono-oxygenase CYP93C subfamily, which contains isoflavone synthase genes from legumes. RNA gel blots and quantitative RT-PCR demonstrated that expression of CYP93C18 increased within 8 h of bruchin treatment to a maximum of 100-200-fold of the level in untreated pods, and then declined. The up-regulation of CYP93C18 was followed by an increase in the level of the isoflavone phytoalexin, pisatin. Pisatin was detectable in the bruchin-treated pods after 16 h and reached a maximum between 32 h and 64 h. This, the first report of induction of phytoalexin biosynthesis by an insect elicitor, suggests that Bruchin B not only stimulates neoplasm formation, but also activates other plant defence responses.

Amino Acid Sequence↗
PubMed2003

Global venous function correlates better than duplex derived reflux to clinical class in the evaluation of chronic venous disease.

AIM: To compare the symptoms and signs of patients with chronic venous disease with the objective results of duplex ultrasound and plethysmography (foot volumetry). METHODS: One hundred and one patients with symptomatic chronic venous disease were investigated with duplex ultrasound and foot volumetry. Patients were classified according to the CEAP classification and the symptoms of pain, heaviness, tiredness, ankle swelling and night cramps were graded. The severity of the disease was judged objectively by the reflux time (sum of reflux time at 6 levels) and the venous function was measured globally with expelled volume (ml) and refilling rate (Q) (ml/100 mlxmin) after exercise, and expelled volume related to foot volume (EVrel), (ml/100 ml). The ratio Q/EVrel)was calculated. Correlation was calculated between clinical class, symptoms and objective parameters. RESULTS: The correlation analyses showed a clear constant relationship between the CEAP clinical classification and the foot volumetry measures (Q/EVrel), r=0.48; p<0.01) There was no such relationship between clinical class and the sum of duplex calculated reflux time (r=-0.05), or between foot volumetry and reflux time. There was no correlation between the clinical class and the total score of symptoms (r=0.044). CONCLUSION: The clinical class of CEAP classification correlates significantly with foot volumetry parameters. There is no correlation between clinical class and reflux time. The severity of the venous disorder and subsequently the need for treatment is more accurately judged by foot volumetry as a global measure. Clinical classification has a realistic meaning concerning the functional evaluation of venous disease.

Adult↗
PubMed2002

A randomised controlled trial of micronised purified flavonoid fraction vs placebo in patients with chronic venous disease.

OBJECTIVE: to evaluate the efficacy of a micronised purified flavonoid fraction (MPFF) in the treatment of chronic venous disease (CVD). DESIGN: prospective double blind, randomised, control study. PATIENTS AND METHODS: one hundred and one patients with symptomatic CVD were randomly allocated to treatment for 60 days with either MPFF (51 patients) or placebo (50 patients) 500 mg twice daily. There were 28 men and 73 women, aged 22-65 years (mean age 48 years). No difference regarding age, gender, clinical class or duration of symptoms was recorded between the treatment and placebo groups. A global score for evaluation of symptoms was used. Patients were investigated with plethysmography (foot-volumetry) and duplex-ultrasonography before and after the treatment period. For statistical comparison Cochran-Mantel-Haenszel test, two-sided Student t-test and covariance analysis were used and p<0.05 was regarded significant. RESULTS: improvement of the global score of symptoms was reported by 21 patients in the MPFF group and by 16 in the placebo group (N.S.). For the whole groups, no significant differences were recorded before and after treatment regarding foot-volumetric or ultrasonographic parameters. On the other hand, in patients with edema (20 in the MPFF group, 23 in the placebo group) ultrasonographic reflux time was significantly reduced for those in the treatment group (p=0.03). This finding did not correlate to clinical symptoms. CONCLUSION: in this study, MPFF did not change the symptoms of CVD, except night cramps. A secondary finding was reduced reflux times in patients with oedema, although no ultrasonographic or foot-volumetric parameters changed significantly for the whole group. The role of MPFF in treatment of patients with CVD needs to be further analysed in a large population.

Adult↗
PubMed2001

Brain tumors.

The total care of a patient with an incurable brain tumor is a complex task. It is best performed by a team of specialized care providers including neurologists, neuro-oncologists, neurosurgeons, radiation oncologists, nurses, neuropsychologists, social workers, and physical and occupational therapists. Hospice providers, and spiritual counselors provide particular skilled services and comfort to patients nearing the end of life. The role and prominence of each team member evolves during the course of the illness as the disease progresses and the symptoms and needs of the patient change. Family members often provide the bulk of the direct care, and themselves require support, education, and counseling. While we currently lack curative therapies for most patients with malignant brain tumors, careful attention to symptom diagnosis and management can greatly enhance the quality of life of a patient with a brain tumor throughout the course of the illness and at the end of life.

Brain Neoplasms↗
PubMed2001

Daily low-dose carboplatin as a radiation sensitizer for newly diagnosed malignant glioma.

Surgical resection followed by local field radiotherapy is currently our most effective approach to treatment for most patients with malignant glioma. Carboplatin chemotherapy has direct cytotoxic effects on glioma cells and acts as a radiation sensitizer to enhance cell killing. Its demonstrated efficacy as a sensitizer in other solid tumors led to this clinical trial of carboplatin as a radiation sensitizer in the treatment of newly diagnosed glioblastoma multiforme (GBM) and anaplastic astrocytoma (AA). Fourteen patients (nine GBM and five AA) were treated with daily low-dose carboplatin 25 mg/m2 intravenously within 2 h of their fractionated radiotherapy to a total dose of 600 mg/m2. No significant toxicities attributable to this combined therapy were observed. All patients have progressed, with median time to progression of 16 weeks. Eleven patients have died, with median survival of 38 weeks for the entire cohort. Although this regimen appeared safe, there was no benefit in survival time compared to historical patients treated with radiotherapy. The limitations and future potential for the strategy of radiation sensitization are discussed.

Adult↗
PubMed2001

Expression profiling of medulloblastoma: PDGFRA and the RAS/MAPK pathway as therapeutic targets for metastatic disease.

Little is known about the genetic regulation of medulloblastoma dissemination, but metastatic medulloblastoma is highly associated with poor outcome. We obtained expression profiles of 23 primary medulloblastomas clinically designated as either metastatic (M+) or non-metastatic (M0) and identified 85 genes whose expression differed significantly between classes. Using a class prediction algorithm based on these genes and a leave-one-out approach, we assigned sample class to these tumors (M+ or M0) with 72% accuracy and to four additional independent tumors with 100% accuracy. We also assigned the metastatic medulloblastoma cell line Daoy to the metastatic class. Notably, platelet-derived growth factor receptor alpha (PDGFRA) and members of the downstream RAS/mitogen-activated protein kinase (MAPK) signal transduction pathway are upregulated in M+ tumors. Immunohistochemical validation on an independent set of tumors shows significant overexpression of PDGFRA in M+ tumors compared to M0 tumors. Using in vitro assays, we show that platelet-derived growth factor alpha (PDGFA) enhances medulloblastoma migration and increases downstream MAP2K1 (MEK1), MAP2K2 (MEK2), MAPK1 (p42 MAPK) and MAPK3 (p44 MAPK) phosphorylation in a dose-dependent manner. Neutralizing antibodies to PDGFRA blocks MAP2K1, MAP2K2 and MAPK1/3 phosphorylation, whereas U0126, a highly specific inhibitor of MAP2K1 and MAP2K2, also blocks MAPK1/3. Both inhibit migration and prevent PDGFA-stimulated migration. These results provide the first insight into the genetic regulation of medulloblastoma metastasis and are the first to suggest a role for PDGFRA and the RAS/MAPK signaling pathway in medulloblastoma metastasis. Inhibitors of PDGFRA and RAS proteins should therefore be considered for investigation as possible novel therapeutic strategies against medulloblastoma.

Butadienes↗
PubMed2001

Finding the balance.

Explore the source record for details and available documents.

Attitude of Health Personnel↗
PubMed2001

CD4(+) T cells and gamma interferon in the long-term control of persistent friend retrovirus infection.

We have used the Friend virus model to determine the basic mechanisms by which the immune system can control persistent retroviral infections. Previously we showed that CD4(+) T cells play an essential role in keeping persistent retrovirus in check. The present in vitro experiments with a Friend virus-specific CD4(+) T-cell clone revealed that these cells produce gamma interferon (IFN-gamma), which acts with two distinct mechanisms of antiviral activity. First, IFN-gamma had a direct inhibitory effect on virus production. This inhibitory effect was noncytolytic and, interestingly, was not associated with decreased cell surface expression of viral antigens. The second mechanism of IFN-gamma-mediated antiviral activity was an enhancement of CD4(+) T-cell-mediated cytolytic activity. We also found an in vivo role for IFN-gamma in the control of persistent Friend virus infections. Neutralization of IFN-gamma in persistently infected mice resulted in significantly increased levels of virus in the spleen, and a significant percentage of IFN-gamma-deficient mice were unable to maintain long-term control over Friend virus infections.

Animals↗
PubMed2001

Male sex workers in three Australian cities: socio-demographic and sex work characteristics.

This article describes the socio-demographic and sex work characteristics of sex workers in Sydney, Melbourne, and Brisbane. A total of 185 male sex workers completed the questionnaire component of the study. The results of this study serve to debunk many of the myths surrounding the popular view of the male sex worker (MSW). The respondents in this study were on average 27 years old, and the majority had completed secondary education, with 30% having gained some form of tertiary qualification. Interestingly, those MSWs who had not completed secondary education were mostly street workers and were generally aged under 25 years. The majority of sex workers lived in rented accommodation, with only 6% reporting to be homeless. Half of all respondents identified as being "gay," 31% as "bisexual" and 5.5% as "straight." More than half of the respondents were in a permanent relationship. Only 7.3% of this group reported using heroin daily, although the majority consumed alcohol, tobacco, marijuana, and ecstasy. The majority of sex workers had been in the profession for less than six months, although some had been working in the industry for more than ten years. Most of the sex workers reported having taken an HIV test and a preference to offer safer sex. The article highlights ways in which the work context of MSW can be better understood and supported by education and public policy programs.

Adult↗
PubMed2001

Development of a human DNA quantitation system.

The AluQuant Human DNA Quantitation System has been developed for human-specific quantitation of forensic samples. This system uses probes specific to repetitive genetic elements allowing quantitation without target amplification. Target immobilization is unnecessary with employment of solution hybridization. The AluQuant Human DNA Quantitation System uses a series of enzymatic reactions to produce a luminescent signal proportional to the quantity of human DNA present. This report demonstrates a range of quantitation from 0.1-50 ng of human DNA. Signal from non-human DNAs tested was insignificant and addition of non-human DNAs into a human sample did not alter quantitation. Lastly, the system was unaffected by degradation of sample through sonication. The AluQuant Human DNA Quantitation System is a simple and sensitive method for quantitating the concentration of human DNA in forensic samples.

DNA↗
PubMed2000

Complete genomic sequence of the human ABCA1 gene: analysis of the human and mouse ATP-binding cassette A promoter.

The ABCA1 gene, a member of the ATP-binding cassette A (ABCA1) transporter superfamily, encodes a membrane protein that facilitates the cellular efflux of cholesterol and phospholipids. Mutations in ABCA1 lead to familial high density lipoprotein deficiency and Tangier disease. We report the complete human ABCA1 gene sequence, including 1,453 bp of the promoter, 146,581 bp of introns and exons, and 1 kb of the 3' flanking region. The ABCA1 gene spans 149 kb and comprises 50 exons. Sixty-two repetitive Alu sequences were identified in introns 1-49. The transcription start site is 315 bp upstream of a newly identified initiation methionine codon and encodes an ORF of 6,783 bp. Thus, the ABCA1 protein is comprised of 2,261 aa. Analysis of the 1,453 bp 5' upstream of the transcriptional start site reveals multiple binding sites for transcription factors with roles in lipid metabolism. Comparative analysis of the mouse and human ABCA1 promoter sequences identified specific regulatory elements, which are evolutionarily conserved. The human ABCA1 promoter fragment -200 to -80 bp that contains binding motifs for SP1, SP3, E-box, and AP1 modulates cellular cholesterol and cAMP regulation of ABCA1 gene expression. These combined findings provide insights into ABCA1-mediated regulation of cellular cholesterol metabolism and will facilitate the identification of new pharmacologic agents for the treatment of atherosclerosis in humans.

ATP Binding Cassette Transporter 1↗