GENETICS SOCIETY OF CANADA AWARD OF EXCELLENCE LECTURE: THE GENETICS OF COMMON FAMILIAL DISORDERS — MAJOR GENES OR MULTIFACTORIAL?

1981 ◽  
Vol 23 (1) ◽  
pp. 1-8 ◽  
Author(s):  
F. C. Fraser
Keyword(s):  
Mathematical Models ◽  
Threshold Model ◽  
Genetic Component ◽  
Pharmacological Agent ◽  
Major Genes ◽  
Predisposing Genes ◽  
The Common ◽  
Low Levels ◽  
Therapeutic Doses ◽  
Familial Disorders

The common familial disorders were, until recently, neglected by geneticists because their familial distributions did not neatly fit the Mendelian mold, and no specific genes could be identified. The multifactorial-threshold model made the familial characteristics of these disorders more intelligible. Although it originally postulated a polygenic genetic component the model can also accommodate one or more major genes with low penetrance. The resulting upsurge of interest has led to (1) the development of increasingly sophisticated mathematical models from which to calculate recurrence risks for specific family situations and (2) the identification of specific predisposing genes in a number of such disorders. One of the corollaries of the model is that any pharmacological agent at therapeutic doses is likely to be teratogenic to at least some embryos, so that regulation should be in terms of "acceptably low" levels of teratogenicity rather than "safety".

Hyperstimulation of the immune system as a cause of autoimmune diseases

2020 ◽  
Vol 75 (3) ◽  
pp. 204-213
Author(s):  
Varvara A. Ryabkova ◽  
Leonid P. Churilov ◽  
Yehuda Shoenfeld
Keyword(s):  
Immune System ◽  
Autoimmune Diseases ◽  
Genetic Basis ◽  
Threshold Model ◽  
Subsequent Development ◽  
Threshold Effect ◽  
Successful Management ◽  
Polygenic Inheritance ◽  
Autoimmune Pathology ◽  
The Common

The pathogenesis of autoimmune diseases is very complex and multi-factorial. The concept of Mosaics of Autoimmunity was introduced to the scientific community 30 years ago by Y. Shoenfeld and D.A. Isenberg, and since then new tiles to the puzzle are continuously added. This concept specifies general pathological ideas about the multifactorial threshold model for polygenic inheritance with a threshold effect by the action of a number of external causal factors as applied to the field of autoimmunology. Among the external factors that can excessively stimulate the immune system, contributing to the development of autoimmune reactions, researchers are particularly interested in chemical substances, which are widely used in pharmacology and medicine. In this review we highlight the autoimmune dynamics i.e. a multistep pathogenesis of autoimmune diseases and the subsequent development of lymphoma in some cases. In this context several issues are addressed namely, genetic basis of autoimmunity; environmental immunostimulatory risk factors; gene/environmental interaction; pre-clinical autoimmunity with the presence of autoantibodies; and the mechanisms, underlying lymphomagenesis in autoimmune pathology. We believe that understanding the common model of the pathogenesis of autoimmune diseases is the first step to their successful management.

scholarly journals Why Do Immigrant and Swedish Adolescents Engage in Ethnic Victimization? Common and Distinct Underlying Factors

2021 ◽  
Vol 50 (11) ◽  
pp. 2236-2248
Author(s):  
S. Bayram Özdemir ◽  
C. Giles ◽  
M. Özdemir
Keyword(s):  
Ethnic Composition ◽  
Attitudes Toward Immigrants ◽  
Factors Associated ◽  
School Settings ◽  
Immigrant Background ◽  
Positive Attitudes ◽  
The Common ◽  
Native Youth ◽  
Low Levels ◽  
Ethnic Victimization

AbstractYouth of immigrant background are at risk of experiencing victimization due to their ethnic or cultural background. However, limited knowledge is available regarding why youth victimize their immigrant peers, and whether the factors associated with engagement in ethnic victimization vary across adolescents of different background. To address this gap in knowledge, the present study aimed to elucidate the common or differential factors associated with engagement in ethnic victimization among immigrant and native youth. The analytical sample included seventh grade students residing in Sweden from 55 classrooms (N = 963, Mage = 13.11, SD = 0.41; 46% girls; 38% youth of immigrant background). The results showed that being morally disengaged and engaging in general victimization are the common denominators of engagement in ethnic victimization for immigrant and Swedish youth. Low levels of positive attitudes toward immigrants provide a foundation for ethnic victimization among Swedish youth, but not youth of immigrant background. Classroom ethnic composition was not significantly related to engagement in ethnic victimization in either group. Predictors of engagement in ethnic victimization seem to have similarities and differences among immigrant and Swedish youth. The factors involved require further attention in developing strategies to combat bias-based hostile behaviors in diverse school settings.

Evaluation of Gas-Liquid Chromatography in Assays for Blood Volatiles

1965 ◽  
Vol 11 (11) ◽  
pp. 1023-1035 ◽  
Author(s):  
Alan Mather ◽  
Angel Assimos
Keyword(s):  
Liquid Chromatography ◽  
Alcohol Concentration ◽  
Quantitative Assay ◽  
Gas Liquid Chromatography ◽  
Internal Reference ◽  
Detection And Identification ◽  
Large Populations ◽  
The Common ◽  
Low Levels ◽  
Better Than

Abstract A simple screening by gas-liquid chromatography (GLC) can provide definitive answers in the detection and identification of a number of volatile substances, including acetone and the common alcohols. After identification, quantitative assay by an internal-reference technic yields highly specific values for ethyl alcohol concentration with a precision at least equal to (and for low levels, better than) that of conventional assays. The unique advantage of GLC is in its simultaneous quantitative assay of mixtures, some of which cannot be satisfactorily assayed or even recognized in any other way. The combination of speed and negligible sample volumes render the technic valuable for sequential studies on capillary blood samples and, potentially, for mass screening of large populations.

scholarly journals Development of a Combined Sensory-Cognitive Measure Based on the Common Cause Hypothesis: Heterogeneous Trajectories and Associated Risk Factors

2019 ◽  
Vol 60 (5) ◽  
pp. e357-e366 ◽  
Author(s):  
Javier de la Fuente ◽  
Dario Moreno-Agostino ◽  
Alejandro de la Torre-Luque ◽  
A Matthew Prina ◽  
Josep María Haro ◽  
...  
Keyword(s):  
Risk Factors ◽  
Cognitive Functioning ◽  
Growth Mixture Modeling ◽  
Common Cause ◽  
Cognitive Difficulties ◽  
Cognitive Measure ◽  
Health Related ◽  
The Common ◽  
Low Levels ◽  
Associated Risk Factors

Abstract Background and Objectives There is a link between sensory and cognitive functioning across old age. However, there are no integrative measures for assessing common determinants of sensory-cognitive functioning. This study aims to develop a combined measure of sensory-cognitive functioning, and to identify heterogeneous trajectories and associated risk factors. Research Design and Methods Two thousand two hundred and fifty-five individuals aged 60 years and over selected from the first six waves (2002–2012) of the English Longitudinal Study of Ageing completed a set of five self-reported visual and hearing functioning items and four cognitive items. Several health-related outcomes were also collected. Results The common cause model presented longitudinal factorial invariance (Tucker-Lewis index [TLI] = 0.989; Comparative Fit Index [CFI] = 0.991; Root Mean Square Error of Approximation [RMSEA] = 0.026). A common factor explained 32%, 36%, and 26% of the visual, hearing, and cognitive difficulties, respectively. The developed sensory-cognitive measure predicted incident dementia over 10 years (area under the curve = .80; 95% confidence interval [CI] = .75, .86). A three-trajectory model was proved to fit better, according to growth mixture modeling. Low levels of education and household wealth, disability, diabetes, high blood pressure, depressive symptoms, and low levels of physical activity were risk factors associated with the classes showing trajectories with a steeper increase of sensory-cognitive difficulties. Discussion and Implications A time-invariant factor explains both sensory and cognitive functioning over 8 years. The sensory-cognitive measure derived from this factor showed a good performance for predicting dementia 10 years later. Several easily identifiable socioeconomic and health-related risk factors could be used as early markers of subsequent sensory-cognitive decline. Therefore, the proposed latent measure could be useful as a cost-effective indicator of sensory-cognitive functioning.

Survival characteristics of the free-living cercarial population of the ectoparasitic digenean Transversotrema patialensis (Soparker, 1924)

Parasitology ◽  
1975 ◽  
Vol 70 (3) ◽  
pp. 295-310 ◽  
Author(s):  
R. M. Anderson ◽  
P. J. Whitfield
Keyword(s):  
Mathematical Models ◽  
Life Span ◽  
Conceptual Understanding ◽  
Biological Processes ◽  
Energy Reserves ◽  
Age Dependence ◽  
Maximum Life Span ◽  
Free Living ◽  
Age Dependent ◽  
Low Levels

The survival characteristics of free-living cercarial populations of Transversotrema patialensis were described and shown to be age-dependent. The maximum life-span was found to be 44 h with a 50% survival at 26 h. Activity and infectivity of the larvae were also characterized by age-dependence, and were demonstrated to be closely correlated with one another. For individual cercariae, both activity and infectivity had dropped to extremely low levels many hours before death occurred. An attempt was made to interrelate activity and infectivity, in a theoretical manner, with the availability of energy reserves.Conceptual understanding of the biological processes involved was aided by the formulation of simple mathematical models.

scholarly journals Using Theory and Measurement to Sharpen Conceptualizations of Mathematics Teaching in the Common Core Era

AERA Open ◽  
2017 ◽  
Vol 3 (1) ◽  
pp. 233285841668056 ◽  
Author(s):  
Mary Kay Stein ◽  
Richard Correnti ◽  
Debra Moore ◽  
Jennifer Lin Russell ◽  
Katelynn Kelly
Keyword(s):  
Student Learning ◽  
Conceptual Understanding ◽  
Teaching And Learning ◽  
Large Scale ◽  
Standardized Test ◽  
Past Research ◽  
Different Types ◽  
The Common ◽  
Low Levels ◽  
Task Sets

We argue that large-scale, standards-based improvements in the teaching and learning of mathematics necessitate advances in our theories regarding how teaching affects student learning and progress in how we measure instruction. Our theory—an embodiment of the interaction of high and low levels of two constructs that past research has shown to influence students’ development of conceptual understanding (explicit attention to concepts and students’ opportunity to struggle)—guided the development of survey-, video-, and artifact-based measures of teaching. Here, we develop a validity argument for the inferences that can be drawn about teaching from these measures by identifying claims and empirical evidence about the extent to which those claims are born out in practice. Results suggest our theory is capturing four patterns of teaching and that it can successfully predict different types of student learning: skills efficiency measured on the state standardized test and conceptual understanding as measured through open-ended task sets.

scholarly journals Visual Symptoms, Vegetative Growth, and Mineral Concentration in Fig Tree (Ficus carica L.) Under Macronutrient Deficiencies

Agronomy ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 787
Author(s):  
Carlos Alberto Garza-Alonso ◽  
Emilio Olivares-Sáenz ◽  
Adriana Gutiérrez-Díez ◽  
Rigoberto E. Vázquez-Alvarado ◽  
Alfredo López-Jiménez
Keyword(s):  
Vegetative Growth ◽  
Dry Weight ◽  
Mineral Concentration ◽  
Hydroponic System ◽  
Visual Symptoms ◽  
Organoleptic Characteristics ◽  
The Common ◽  
Fig Tree ◽  
Low Levels ◽  
Element Technique

The common fig is an edible fruit which is appreciated for its organoleptic characteristics and high commercial value. Several factors, including mineral nutrition, affect fig production. Macronutrients fulfill specific functions in the metabolism of plants, affecting some functions when they are at low levels. So, in the present investigation, the visual symptoms of nitrogen, phosphorus, potassium, calcium, and magnesium deficiencies were identified and characterized, as well as their effects on vegetative growth and the concentration of minerals in fig tree tissues, using the missing element technique in a controlled hydroponic system. N was the element that most affected vegetative growth, causing smaller stem diameter, leaf area, and dry weight. Treatments without P and K followed. In addition, significant differences were found in the mineral concentration in leaf, stem, and root, with various interactions of antagonism and synergism observed according to the absence of each element.

Mathematical models of transmission and control of infectious agents

2021 ◽  
pp. 241-258
Author(s):  
Alex Welte ◽  
Cari van Schalkwyk
Keyword(s):  
Public Health ◽  
Mathematical Modelling ◽  
Mathematical Models ◽  
Statistical Modelling ◽  
Model Construction ◽  
Primary Data ◽  
Infectious Agents ◽  
The Common ◽  
And Control ◽  
Epidemiological Situation

Indeed, the ‘heavy lifting’ of healthcare is in the care of patients, the development and distribution of vaccines, drugs and devices, and the conception and implementation of sensible systems and policies. However, in recent decades, spectacular increases in the availability of computational capacity have paved the way for mathematical modelling to play an ever-increasing role in many aspects of public health, by supporting formal analyses at various scales of the processes involved. This chapter explores a particular kind of ‘modelling’—and it is not the common (bio)statistical kind. We focus on what we would call ‘dynamical’ modelling (as opposed to ‘statistical’ modelling). This essentially entails the reduction, to mathematics, of key facts and principles inherent in the ‘processes’ or ‘mechanisms’ in an epidemiological situation. We can then manipulate these mathematical constructs, in search of insights that, while ultimately implied in the model construction, are not superficially apparent from our primary data and our intuition.

scholarly journals Energy Conservation via Hydrogen Cycling in the Methanogenic ArchaeonMethanosarcina barkeri

mBio ◽  
2018 ◽  
Vol 9 (4) ◽  
Author(s):  
Gargi Kulkarni ◽  
Thomas D. Mand ◽  
William W. Metcalf
Keyword(s):  
Energy Conservation ◽  
Direct Evidence ◽  
Methanosarcina Barkeri ◽  
Content Type ◽  
Anaerobic Microorganisms ◽  
Transport Chain ◽  
Substrate Level ◽  
The Common ◽  
Low Levels ◽  
Living Organisms

ABSTRACTEnergy conservation via hydrogen cycling, which generates proton motive force by intracellular H2production coupled to extracellular consumption, has been controversial since it was first proposed in 1981. It was hypothesized that the methanogenic archaeonMethanosarcina barkeriis capable of energy conservation via H2cycling, based on genetic data that suggest that H2is a preferred, but nonessential, intermediate in the electron transport chain of this organism. Here, we characterize a series of hydrogenase mutants to provide direct evidence of H2cycling.M. barkeriproduces H2during growth on methanol, a phenotype that is lost upon mutation of the cytoplasmic hydrogenase encoded byfrhADGB, although low levels of H2, attributable to the Ech hydrogenase, accumulate during stationary phase. In contrast, mutations that conditionally inactivate the extracellular Vht hydrogenase are lethal when expression of thevhtGACDoperon is repressed. Under these conditions, H2accumulates, with concomitant cessation of methane production and subsequent cell lysis, suggesting that the inability to recapture extracellular H2is responsible for the lethal phenotype. Consistent with this interpretation, double mutants that lack both Vht and Frh are viable. Thus, when intracellular hydrogen production is abrogated, loss of extracellular H2consumption is no longer lethal. The common occurrence of both intracellular and extracellular hydrogenases in anaerobic microorganisms suggests that this unusual mechanism of energy conservation may be widespread in nature.IMPORTANCEATP is required by all living organisms to facilitate essential endergonic reactions required for growth and maintenance. Although synthesis of ATP by substrate-level phosphorylation is widespread and significant, most ATP is made via the enzyme ATP synthase, which is energized by transmembrane chemiosmotic gradients. Therefore, establishing this gradient across the membrane is of central importance to sustaining life. Experimental validation of H2cycling adds to a short list of mechanisms for generating a transmembrane electrochemical gradient that is likely to be widespread, especially among anaerobic microorganisms.

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