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Weak Positive (weak + positive)

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Medical Sciences100%

Terms modified by Weak Positive

  • weak positive correlation
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    Selected Abstracts

    Genetic parameters for individual birth and weaning weight and for litter size of Large White pigs

    JOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 3 2000
    D. Kaufmann
    Summary Data from a French experimental herd recorded between 1990 and 1997 were used to estimate genetic parameters for individual birth and weaning weight, as well as litter size of Large White pigs using restricted maximum likelihood (REML) methodology applied to a multivariate animal model. In addition to fixed effects the model included random common environment of litter, direct and maternal additive genetic effects. The data consisted of 1928 litters including individual weight observations from 18151 animals for birth weight and from 15360 animals for weaning weight with 5% of animals transferred to a nurse. Estimates of direct and maternal heritability and proportion of the common environmental variance for birth weight were 0.02, 0.21 and 0.11, respectively. The corresponding values for weaning weight were 0.08, 0.16 and 0.23 and for litter size 0.22, 0.02 and 0.06, respectively. The direct and the maternal genetic correlations between birth and weaning weight were positive (0.59 and 0.76). Weak positive (negative) genetic correlations between direct effects on weight traits and maternal effects on birth weight (weaning weight) were found. Negative correlations were found between direct genetic effect for litter size and maternal genetic effects on all three traits. The negative relationship between litter size and individual weight requires a combined selection for litter size and weight. Zusammenfassung Daten einer französischen Versuchsherde aus den Jahren 1990 bis 1997 wurden für die Schätzung von genetischen Parametern für individuelles Geburts-, Absetzgewicht und Wurfgrösse bei französischen Large White verwendet. Die Schätzung der Parameter erfolgte mit der Restricted Maximum Likelihood Methode (REML) angewandt auf ein multivariates Tiermodell. Neben fixen Effekten berücksichtigte das Modell die zufällige gemeinsame Wurfumwelt und direkte und maternale additiv genetische Effekte. Der Datensatz bestand aus 1928 Wurfaufzeichnungen mit Angaben zum individuellen Geburtsgewicht von 18151 Tieren und zum Absetzgewicht von 15360 Tieren. Nach der Geburt wurden 5% der Ferkel in einen anderen Wurf versetzt. Die geschätzten Werte für die direkte, die maternale Heritabilität und den Varianzanteil der Wurfumwelt waren für das Geburtsgewicht 0.02, 0.21 und 0.11. Die entsprechenden Werte für das Absetzgewicht waren 0.08, 0.16 und 0.23 und für die Wurfgrösse 0.22, 0.02 und 0.06. Die direkten und die maternalen genetischen Korrelationen zwischen Geburts-und Absetzgewicht waren positiv (0.59 und 0.76). Schwache positive (negative) genetische Korrelationen wurden zwischen den direkten genetischen Effekten auf die Gewichtsmerkmale und dem maternalen genetischen Effekt auf das Geburtsgewicht (Absetzgewicht) gefunden. Negative Korrelationen gab es zwischen dem direkten genetischen Effekt auf die Wurfgrösse und den maternalen genetischen Effekten auf alle drei Merkmale. Die negative Beziehung zwischen Wurfgrösse und individuellem Gewicht verlangt nach einer kombinierten Selektion für Wurfgrösse und Gewicht. [source]

    FC02.4 Meteorological factors and standard series patch test reactions

    CONTACT DERMATITIS, Issue 3 2004
    Janice Hegewald
    The existence of seasonal patterns to patch test reactions has been described, but with conflicting causal interpretations. The potential seasonality of patch tests may be due to irritation, changes to skin barrier or changes to immunological functions caused by meteorological fluctuations. For example, increased skin irritability due to cold winter weather and low humidity may cause an increase in irritative/doubtful and weak positive (false positive) reactions. To investigate the extent of the association between weather and patch test results, consecutive patients (N = 73691) patch tested with the standard series of the German Contact Dermatitis Research Group (DKG) at German or Austrian IVDK (http://www.ivdk.de) centres were matched with weather data collected at a nearby (30 km radius) weather station. Temperature and absolute humidity (AH) on the day of patch test application and the two preceding days were averaged to represent the environment most likely to have influenced the skin condition at the time of testing. The results of 24 standard series substances were analyzed with multivariate logistic regression. Half of the standard series substances examined, including fragrance mix, nickel sulphate, and formaldehyde, exhibited evidence of a relationship with meteorological conditions. Fragrance mix and p-Phenylene diamine exhibited the strongest evidence of an association to weather, with the odds of the reactions in all three reaction categories (ir/?, +, ++/+++) increasing during winter conditions. Due to the association between weather and patch test reactivity, the potential effect of meteorological conditions should be considered in the interpretation of patch test reactions. [source]

    Allergy and infectious disease histories and the risk of childhood acute lymphoblastic leukaemia

    PAEDIATRIC & PERINATAL EPIDEMIOLOGY, Issue 2 2005
    Paula F. Rosenbaum
    Summary Infectious disease histories were evaluated in a population-based case-control study of childhood acute lymphoblastic leukaemia (ALL) as it has been hypothesised that delays in early infections are associated with an increased risk of disease. Allergy histories were also assessed as part of a broader evaluation of the role of immune factors in ALL. Cases (n = 255) were diagnosed between 1980 and 1991 at one of four referral centres in a 31-county area of New York State; controls (n = 760) were a random sample of live births from the same region, frequency matched to cases by sex, race and birth year. Data were collected by mailed questionnaire, completed by case and control parents in 1995. Allergy and infectious histories before the age at leukaemia diagnosis for cases and an equivalent age for controls were evaluated. The adjusted odds ratio and 95% confidence interval [CI] associated with a positive history of any allergy was 0.58 [95% CI 0.38, 0.88] compared with a negative allergy history. The occurrence of several common childhood illnesses before 25 months of age and ALL were assessed, with both weak positive and weak inverse associations observed. Overall, these analyses provide little support for the hypothesis that infection delay in early life is associated with an increased risk of ALL. Children with positive allergy histories reported significantly more infections than those with negative histories; however, effect modification of the infection-ALL associations by child allergy history was not observed. Nonetheless, these observations suggest the importance of assessing both allergy and infectious histories and their possible interactions when evaluating the association between these immune factors and childhood ALL. [source]

    A medium-term rat liver bioassay for rapid in vivo detection of carcinogenic potential of chemicals

    CANCER SCIENCE, Issue 1 2003
    Nobuyuki Lto
    A reliable medium-term bioassay system for rapid detection of carcinogenic potential of chemicals in the human environment has been developed. The 8-week-protocol consists of 2 stages; male F344 rats are given a single intraperitoneal injection of diethylnitrosamine (200 mg/kg) for initiation of liver carcinogenesis, followed by a 6-week test chemical treatment starting 2 weeks thereafter. Test chemicals are usually given in the diet or the drinking water and in the 2nd week of test chemical treatment, all rats are subjected to two-thirds partial hepatectomy in order to induce regenerative cell replication. The end-point marker is the glutathione S-transferase placental form (GST-P)-positive hepatic focus, the numbers and sizes of which are analyzed using an image-analyzer and expressed as values per unit liver section (1 cm2). When the yield of GST-P-positive foci is significantly enhanced (P<0.05) over the control value, a chemical is judged to possess carcinogenic or promotion potential for the liver. Among 313 chemicals already tested in this system in our laboratory, 30/31 (97%) mutagenic hepatocarcinogens and 29/33 (88%) non-mutagenic hepatocarcinogens gave positive results. Ten out of 43 (23%) agents known to be carcinogenic in organs other than the liver were also positive. It is particularly important that only one of 48 non-carcinogens gave a very weak positive result, so that the system has a very low false-positivity rate. It is now well documented that the assay system is highly effective for detecting hepatocarcinogens, bridging the gap between traditional long-term carcinogenicity tests and short-term screening assays. At the Fourth International Conference on Harmonization, our medium-term liver bioassay based on an initiation and promotion protocol was recommended in the guidelines as an acceptable alternative to the long-term rodent carcinogenicity test. (Cancer Sci 2003; 94: 3,8) [source]