LIVIVO - The Search Portal for Life Sciences

zur deutschen Oberfläche wechseln
Advanced search

Your last searches

  1. AU="Kaiser, Jan Christian"
  2. AU="Torres, Flaviene Felix"

Search results

Result 1 - 10 of total 46

Search options

  1. Article ; Online: Shape-specific characterization of colorectal adenoma growth and transition to cancer with stochastic cell-based models.

    Simonetto, Cristoforo / Mansmann, Ulrich / Kaiser, Jan Christian

    PLoS computational biology

    2023  Volume 19, Issue 1, Page(s) e1010831

    Abstract: Colorectal adenoma are precursor lesions on the pathway to cancer. Their removal in screening colonoscopies has markedly reduced rates of cancer incidence and death. Generic models of adenoma growth and transition to cancer can guide the implementation ... ...

    Abstract Colorectal adenoma are precursor lesions on the pathway to cancer. Their removal in screening colonoscopies has markedly reduced rates of cancer incidence and death. Generic models of adenoma growth and transition to cancer can guide the implementation of screening strategies. But adenoma shape has rarely featured as a relevant risk factor. Against this backdrop we aim to demonstrate that shape influences growth dynamics and cancer risk. Stochastic cell-based models are applied to a data set of 197,347 Bavarian outpatients who had colonoscopies from 2006-2009, 50,649 patients were reported with adenoma and 296 patients had cancer. For multi-stage clonal expansion (MSCE) models with up to three initiating stages parameters were estimated by fits to data sets of all shapes combined, and of sessile (70% of all adenoma), peduncular (17%) and flat (13%) adenoma separately for both sexes. Pertinent features of adenoma growth present themselves in contrast to previous assumptions. Stem cells with initial molecular changes residing in early adenoma predominantly multiply within two-dimensional structures such as crypts. For these cells mutation and division rates decrease with age. The absolute number of initiated cells in an adenoma of size 1 cm is small around 103, related to all bulk cells they constitute a share of about 10-5. The notion of very few proliferating stem cells with age-decreasing division rates is supported by cell marker experiments. The probability for adenoma transiting to cancer increases with squared linear size and shows a shape dependence. Compared to peduncular and flat adenoma, it is twice as high for sessile adenoma of the same size. We present a simple mathematical expression for the hazard ratio of interval cancers which provides a mechanistic understanding of this important quality indicator. We conclude that adenoma shape deserves closer consideration in screening strategies and as risk factor for transition to cancer.
    MeSH term(s) Male ; Female ; Humans ; Colorectal Neoplasms/pathology ; Colonoscopy/methods ; Risk Factors ; Incidence ; Adenoma/diagnosis
    Language English
    Publishing date 2023-01-23
    Publishing country United States
    Document type Journal Article
    ZDB-ID 2193340-6
    ISSN 1553-7358 ; 1553-734X
    ISSN (online) 1553-7358
    ISSN 1553-734X
    DOI 10.1371/journal.pcbi.1010831
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  2. Article ; Online: Socioeconomic correlates of SARS-CoV-2 and influenza H1N1 outbreaks.

    Kaiser, Jan Christian / Stathopoulos, Georgios T

    The European respiratory journal

    2020  Volume 56, Issue 3

    MeSH term(s) Betacoronavirus ; COVID-19 ; Coronavirus Infections/epidemiology ; Coronavirus Infections/mortality ; Disease Outbreaks ; Gross Domestic Product ; Health Expenditures ; Humans ; Influenza A Virus, H1N1 Subtype ; Influenza, Human/epidemiology ; Influenza, Human/mortality ; Linear Models ; Pandemics ; Pneumonia, Viral/epidemiology ; Pneumonia, Viral/mortality ; Population Density ; Regression Analysis ; Risk Factors ; SARS-CoV-2 ; Socioeconomic Factors ; Urbanization
    Keywords covid19
    Language English
    Publishing date 2020-09-17
    Publishing country England
    Document type Letter
    ZDB-ID 639359-7
    ISSN 1399-3003 ; 0903-1936
    ISSN (online) 1399-3003
    ISSN 0903-1936
    DOI 10.1183/13993003.01400-2020
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  3. Article ; Online: Heterogeneity in coronary heart disease risk.

    Simonetto, Cristoforo / Rospleszcz, Susanne / Kaiser, Jan Christian / Furukawa, Kyoji

    Scientific reports

    2022  Volume 12, Issue 1, Page(s) 10131

    Abstract: There is large inter-individual heterogeneity in risk of coronary heart disease (CHD). Risk factors traditionally used in primary risk assessment only partially explain this heterogeneity. Residual, unobserved heterogeneity leads to age-related ... ...

    Abstract There is large inter-individual heterogeneity in risk of coronary heart disease (CHD). Risk factors traditionally used in primary risk assessment only partially explain this heterogeneity. Residual, unobserved heterogeneity leads to age-related attenuation of hazard rates and underestimation of hazard ratios. Its magnitude is unknown. Therefore, we aimed to estimate a lower and an approximate upper bound. Heterogeneity was parametrized by a log-normal distribution with shape parameter σ. Analysis was based on published data. From concordance indices of studies including traditional risk factors and additional diagnostic imaging data, we calculated the part of heterogeneity explained by imaging data. For traditional risk assessment, this part typically remains unexplained, thus constituting a lower bound on unobserved heterogeneity. Next, the potential impact of heterogeneity on CHD hazard rates in several large countries was investigated. CHD rates increase with age but the increase attenuates with age. Presuming this attenuation to be largely caused by heterogeneity, an approximate upper bound on σ was derived. Taking together both bounds, unobserved heterogeneity in studies without imaging information can be described by a shape parameter in the range σ = 1-2. It substantially contributes to observed age-dependences of hazard ratios and may lead to underestimation of hazard ratios by a factor of about two. Therefore, analysis of studies for primary CHD risk assessment should account for unobserved heterogeneity.
    MeSH term(s) Coronary Disease/epidemiology ; Coronary Disease/etiology ; Humans ; Proportional Hazards Models ; Risk Assessment ; Risk Factors
    Language English
    Publishing date 2022-06-16
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/s41598-022-14013-3
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  4. Article ; Online: Concepts of association between cancer and ionising radiation: accounting for specific biological mechanisms.

    Eidemüller, Markus / Becker, Janine / Kaiser, Jan Christian / Ulanowski, Alexander / Apostoaei, A Iulian / Hoffman, F Owen

    Radiation and environmental biophysics

    2023  Volume 62, Issue 1, Page(s) 1–15

    Abstract: The probability that an observed cancer was caused by radiation exposure is usually estimated using cancer rates and risk models from radioepidemiological cohorts and is called assigned share (AS). This definition implicitly assumes that an ongoing ... ...

    Abstract The probability that an observed cancer was caused by radiation exposure is usually estimated using cancer rates and risk models from radioepidemiological cohorts and is called assigned share (AS). This definition implicitly assumes that an ongoing carcinogenic process is unaffected by the studied radiation exposure. However, there is strong evidence that radiation can also accelerate an existing clonal development towards cancer. In this work, we define different association measures that an observed cancer was newly induced, accelerated, or retarded. The measures were quantified exemplarily by Monte Carlo simulations that track the development of individual cells. Three biologically based two-stage clonal expansion (TSCE) models were applied. In the first model, radiation initiates cancer development, while in the other two, radiation has a promoting effect, i.e. radiation accelerates the clonal expansion of pre-cancerous cells. The parameters of the TSCE models were derived from breast cancer data from the atomic bomb survivors of Hiroshima and Nagasaki. For exposure at age 30, all three models resulted in similar estimates of AS at age 60. For the initiation model, estimates of association were nearly identical to AS. However, for the promotion models, the cancerous clonal development was frequently accelerated towards younger ages, resulting in associations substantially higher than AS. This work shows that the association between a given cancer and exposure in an affected person depends on the underlying biological mechanism and can be substantially larger than the AS derived from classic radioepidemiology.
    MeSH term(s) Humans ; Adult ; Middle Aged ; Neoplasms, Radiation-Induced/epidemiology ; Neoplasms, Radiation-Induced/etiology ; Nuclear Warfare ; Models, Biological ; Carcinogenesis ; Radiation, Ionizing ; Japan
    Language English
    Publishing date 2023-01-12
    Publishing country Germany
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 124987-3
    ISSN 1432-2099 ; 0301-634X
    ISSN (online) 1432-2099
    ISSN 0301-634X
    DOI 10.1007/s00411-022-01012-1
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  5. Article ; Online: Biologically-based modeling of radiation risk and biomarker prevalence for papillary thyroid cancer in Japanese a-bomb survivors 1958-2005.

    Kaiser, Jan Christian / Misumi, Munechika / Furukawa, Kyoji

    International journal of radiation biology

    2020  Volume 97, Issue 1, Page(s) 19–30

    Abstract: Purpose: Thyroid cancer of papillary histology (PTC) is the dominant type in radio-epidemiological cohorts established after nuclear accidents or warfare. Studies on post-Chernobyl PTC and on thyroid cancer in the life span study (LSS) of Japanese a- ... ...

    Abstract Purpose: Thyroid cancer of papillary histology (PTC) is the dominant type in radio-epidemiological cohorts established after nuclear accidents or warfare. Studies on post-Chernobyl PTC and on thyroid cancer in the life span study (LSS) of Japanese a-bomb survivors consistently revealed high radiation risk after exposure during childhood and adolescence. For post-Chernobyl risk assessment overexpression of the CLIP2 gene was proposed as molecular biomarker to separate radiogenic from sporadic PTC. Based on such binary marker a biologically-based risk model of PTC carcinogenesis has been developed for observational Chernobyl data. The model featured two independent molecular pathways of disease development, of which one was associated with radiation exposure. To gain credibility the concept for a mechanistic risk model must be based on general biological features which transcend findings in a single cohort. The purpose of the present study is therefore to demonstrate portability of the model concept by application to PTC incidence data in the LSS. By exploiting the molecular two-path concept we improve the determination of the probability of radiation causing cancer (POC).
    Materials and methods: The current analysis uses thyroid cancer incidence data of the LSS with thyroid cancer diagnoses and papillary histology (
    Results: Judged by goodness-of-fit all applied models described the data almost equally well. They yielded similar risk estimates in cohorts post-Chernobyl and LSS. The preferred mechanistic model was selected by biological plausibility. It reflected important features of an imperfect radiation marker which are not easily addressed by descriptive models. Precise model predictions of marker prevalence in strata of epidemiological covariables can be tested by molecular measurements. Application of the radiation-related molecular pathway from our preferred model in retrospective risk assessment decreases the threshold dose for 50% POC from 0.33 (95% confidence interval (CI) 0.18; 0.64) Gy to 0.04 (95% CI 0.01; 0.19) Gy for females and from 0.43 (95% CI 0.17; 1.84) Gy to 0.19 (95% CI 0.05; 1.00) Gy for males. These improvements are still not sufficient to separate radiation-induced from sporadic PTC cases at very low doses <0.015 Gy typical for the Fukushima accident.
    Conclusions: Successful application of our preferred mechanistic model to LSS incidence data confirms and improves the biological two-path concept of radiation-induced PTC. Model predictions suggest further molecular validation studies to consolidate the basis of biologically-based risk estimation.
    MeSH term(s) Adolescent ; Female ; Humans ; Japan ; Male ; Models, Biological ; Neoplasms, Radiation-Induced/etiology ; Nuclear Warfare ; Risk Assessment ; Survivors ; Thyroid Cancer, Papillary/etiology ; Thyroid Neoplasms/etiology
    Language English
    Publishing date 2020-07-02
    Publishing country England
    Document type Journal Article
    ZDB-ID 3065-x
    ISSN 1362-3095 ; 0020-7616 ; 0955-3002
    ISSN (online) 1362-3095
    ISSN 0020-7616 ; 0955-3002
    DOI 10.1080/09553002.2020.1784488
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  6. Article ; Online: Biologically based models of cancer risk in radiation research.

    Kaiser, Jan Christian / Blettner, Maria / Stathopoulos, Georgios T

    International journal of radiation biology

    2020  Volume 97, Issue 1, Page(s) 2–11

    MeSH term(s) Biomarkers ; Databases, Factual ; Humans ; Models, Biological ; Neoplasms, Radiation-Induced/etiology ; Radiation Dosage ; Radiation Protection ; Research Design ; Risk Assessment
    Chemical Substances Biomarkers
    Language English
    Publishing date 2020-07-16
    Publishing country England
    Document type Journal Article
    ZDB-ID 3065-x
    ISSN 1362-3095 ; 0020-7616 ; 0955-3002
    ISSN (online) 1362-3095
    ISSN 0020-7616 ; 0955-3002
    DOI 10.1080/09553002.2020.1784490
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  7. Article ; Online: Simonetto et al. Respond to "Mechanistic Models in Epidemiology".

    Simonetto, Cristoforo / Heier, Margit / Peters, Annette / Kaiser, Jan Christian / Rospleszcz, Susanne

    American journal of epidemiology

    2022  Volume 191, Issue 10, Page(s) 1781–1782

    Language English
    Publishing date 2022-06-02
    Publishing country United States
    Document type Journal Article ; Comment
    ZDB-ID 2937-3
    ISSN 1476-6256 ; 0002-9262
    ISSN (online) 1476-6256
    ISSN 0002-9262
    DOI 10.1093/aje/kwac100
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  8. Article ; Online: From Atherosclerosis to Myocardial Infarction: A Process-Oriented Model Investigating the Role of Risk Factors.

    Simonetto, Cristoforo / Heier, Margit / Peters, Annette / Kaiser, Jan Christian / Rospleszcz, Susanne

    American journal of epidemiology

    2022  Volume 191, Issue 10, Page(s) 1766–1775

    Abstract: Mathematical models are able to reflect biological processes and to capture epidemiologic data. Thus, they may help elucidate roles of risk factors in disease progression. We propose to account for smoking, hypertension, and dyslipidemia in a previously ... ...

    Abstract Mathematical models are able to reflect biological processes and to capture epidemiologic data. Thus, they may help elucidate roles of risk factors in disease progression. We propose to account for smoking, hypertension, and dyslipidemia in a previously published process-oriented model that describes the development of atherosclerotic lesions resulting in myocardial infarction (MI). The model is sex-specific and incorporates individual heterogeneity. It was applied to population-based individual risk factors and MI rates (Cooperative Health Research in the Region of Augsburg (KORA) study) together with subclinical atherosclerotic lesion data (Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study). Different model variants were evaluated, testing the association of risk factors with different disease processes. Best fits were obtained for smoking affecting a late-stage disease process, suggesting a thrombogenic role. Hypertension was mainly related to complicated, vulnerable lesions. Dyslipidemia was consistent with increasing the number of initial lesions. By accounting for heterogeneity, individual hazard ratios differ from the population average. The mean individual hazard ratio for smoking was twice the population-based hazard ratio for men and even more for women. Atherosclerotic lesion progression and MI incidence data can be related in a mathematical model to illuminate how risk factors affect different phases of this pathological process.
    MeSH term(s) Adolescent ; Atherosclerosis/epidemiology ; Atherosclerosis/etiology ; Dyslipidemias ; Female ; Humans ; Hypertension/complications ; Hypertension/epidemiology ; Male ; Myocardial Infarction/epidemiology ; Myocardial Infarction/etiology ; Risk Factors
    Language English
    Publishing date 2022-02-25
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2937-3
    ISSN 1476-6256 ; 0002-9262
    ISSN (online) 1476-6256
    ISSN 0002-9262
    DOI 10.1093/aje/kwac038
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

  9. Article ; Online: Simulating the dynamics of atherosclerosis to the incidence of myocardial infarction, applied to the KORA population.

    Simonetto, Cristoforo / Rospleszcz, Susanne / Heier, Margit / Meisinger, Christa / Peters, Annette / Kaiser, Jan Christian

    Statistics in medicine

    2021  Volume 40, Issue 14, Page(s) 3299–3312

    Abstract: Analyzing epidemiological data with simplified mathematical models of disease development provides a link between the time-course of incidence and the underlying biological processes. Here we point out that considerable modeling flexibility is gained if ... ...

    Abstract Analyzing epidemiological data with simplified mathematical models of disease development provides a link between the time-course of incidence and the underlying biological processes. Here we point out that considerable modeling flexibility is gained if the model is solved by simulation only. To this aim, a model of atherosclerosis is proposed: a Markov Chain with continuous state space which represents the coronary artery intimal surface area involved with atherosclerotic lesions of increasing severity. Myocardial infarction rates are assumed to be proportional to the area of most severe lesions. The model can be fitted simultaneously to infarction incidence rates observed in the KORA registry, and to the age-dependent prevalence and extent of atherosclerotic lesions in the PDAY study. Moreover, the simulation approach allows for non-linear transition rates, and to consider at the same time randomness and inter-individual heterogeneity. Interestingly, the fit revealed significant age dependence of parameters in females around the age of menopause, qualitatively reproducing the known vascular effects of female sex hormones. For males, the incidence curve flattens for higher ages. According to the model, frailty explains this flattening only partially, and saturation of the disease process plays also an important role. This study shows the feasibility of simulating subclinical and epidemiological data with the same mathematical model. The approach is very general and may be extended to investigate the effects of risk factors or interventions. Moreover, it offers an interface to integrate quantitative individual health data as assessed, for example, by imaging.
    MeSH term(s) Atherosclerosis ; Female ; Humans ; Incidence ; Male ; Myocardial Infarction ; Registries ; Risk Factors
    Language English
    Publishing date 2021-05-19
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 843037-8
    ISSN 1097-0258 ; 0277-6715
    ISSN (online) 1097-0258
    ISSN 0277-6715
    DOI 10.1002/sim.8951
    Database MEDical Literature Analysis and Retrieval System OnLINE

    More links

    Kategorien

To top