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  1. Article ; Online: Recursive computed ABC (cABC) analysis as a precise method for reducing machine learning based feature sets to their minimum informative size.

    Lötsch, Jörn / Ultsch, Alfred

    Scientific reports

    2023  Volume 13, Issue 1, Page(s) 5470

    Abstract: Selecting the k best features is a common task in machine learning. Typically, a few features have high importance, but many have low importance (right-skewed distribution). This report proposes a numerically precise method to address this skewed feature ...

    Abstract Selecting the k best features is a common task in machine learning. Typically, a few features have high importance, but many have low importance (right-skewed distribution). This report proposes a numerically precise method to address this skewed feature importance distribution in order to reduce a feature set to the informative minimum of items. Computed ABC analysis (cABC) is an item categorization method that aims to identify the most important items by partitioning a set of non-negative numerical items into subsets "A", "B", and "C" such that subset "A" contains the "few important" items based on specific properties of ABC curves defined by their relationship to Lorenz curves. In its recursive form, the cABC analysis can be applied again to subset "A". A generic image dataset and three biomedical datasets (lipidomics and two genomics datasets) with a large number of variables were used to perform the experiments. The experimental results show that the recursive cABC analysis limits the dimensions of the data projection to a minimum where the relevant information is still preserved and directs the feature selection in machine learning to the most important class-relevant information, including filtering feature sets for nonsense variables. Feature sets were reduced to 10% or less of the original variables and still provided accurate classification in data not used for feature selection. cABC analysis, in its recursive variant, provides a computationally precise means of reducing information to a minimum. The minimum is the result of a computation of the number of k most relevant items, rather than a decision to select the k best items from a list. In addition, there are precise criteria for stopping the reduction process. The reduction to the most important features can improve the human understanding of the properties of the data set. The cABC method is implemented in the Python package "cABCanalysis" available at https://pypi.org/project/cABCanalysis/ .
    Language English
    Publishing date 2023-04-04
    Publishing country England
    Document type Journal Article
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/s41598-023-32396-9
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Comments on the importance of visualizing the distribution of pain-related data.

    Lötsch, Jörn / Ultsch, Alfred

    European journal of pain (London, England)

    2023  Volume 27, Issue 7, Page(s) 787–793

    MeSH term(s) Humans ; Pain
    Language English
    Publishing date 2023-05-24
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 1390424-3
    ISSN 1532-2149 ; 1090-3801
    ISSN (online) 1532-2149
    ISSN 1090-3801
    DOI 10.1002/ejp.2135
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Artificial intelligence and machine learning in clinical pharmacological research.

    Mayer, Benjamin / Kringel, Dario / Lötsch, Jörn

    Expert review of clinical pharmacology

    2024  Volume 17, Issue 1, Page(s) 79–91

    Abstract: Background: Clinical pharmacology research has always involved computational analysis. With the abundance of drug-related data available, the integration of artificial intelligence (AI) and machine learning (ML) methods has emerged as a promising way to ...

    Abstract Background: Clinical pharmacology research has always involved computational analysis. With the abundance of drug-related data available, the integration of artificial intelligence (AI) and machine learning (ML) methods has emerged as a promising way to enhance clinical pharmacology research.
    Methods: Based on an accepted definition of clinical pharmacology as a field of research dealing with all aspects of drug-human interactions, the analysis included publications from institutes specializing in clinical pharmacology. Research topics and the most used machine learning methods in clinical pharmacology were retrieved from the PubMed database and summarized.
    Results: ML was identified in 674 publications attributed to clinical pharmacology research, with a significant increase in publication activity over the last decade. Notable research topics addressed by ML/AI included Covid-19-related clinical pharmacology research, clinical neuropharmacology, drug safety and risk assessment, clinical pharmacology related to cancer research, and antimicrobial and antiviral research unrelated to Covid-19. In terms of ML methods, neural networks, random forests, and support vector machines were frequently mentioned in the abstracts of the retrieved papers.
    Conclusions: ML, and AI in general, is increasingly being used in various research areas within clinical pharmacology. This report presents specific examples of applications and highlights the most used ML methods.
    MeSH term(s) Humans ; Artificial Intelligence ; Machine Learning ; COVID-19 ; Pharmacology, Clinical
    Language English
    Publishing date 2024-01-23
    Publishing country England
    Document type Journal Article
    ISSN 1751-2441
    ISSN (online) 1751-2441
    DOI 10.1080/17512433.2023.2294005
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Odor dilution sorting as a clinical test of olfactory function: normative values and reliability data.

    Lötsch, Jörn / Wolter, Anne / Hähner, Antje / Hummel, Thomas

    Chemical senses

    2024  Volume 49

    Abstract: Clinical assessment of an individual's sense of smell has gained prominence, but its resource-intensive nature necessitates the exploration of self-administered methods. In this study, a cohort of 68 patients with olfactory loss and 55 controls were ... ...

    Abstract Clinical assessment of an individual's sense of smell has gained prominence, but its resource-intensive nature necessitates the exploration of self-administered methods. In this study, a cohort of 68 patients with olfactory loss and 55 controls were assessed using a recently introduced olfactory test. This test involves sorting 2 odorants (eugenol and phenylethyl alcohol) in 5 dilutions according to odor intensity, with an average application time of 3.5 min. The sorting task score, calculated as the mean of Kendall's Tau between the assigned and true dilution orders and normalized to [0,1], identified a cutoff for anosmia at a score ≤ 0.7. This cutoff, which marks the 90th percentile of scores obtained with randomly ordered dilutions, had a balanced accuracy of 89% (78% to 97%) for detecting anosmia, comparable to traditional odor threshold assessments. Retest evaluations suggested a score difference of ±0.15 as a cutoff for clinically significant changes in olfactory function. In conclusion, the olfactory sorting test represents a simple, self-administered approach to the detection of anosmia or preserved olfactory function. With balanced accuracy similar to existing brief olfactory tests, this method offers a practical and user-friendly alternative for screening anosmia, addressing the need for resource-efficient assessments in clinical settings.
    MeSH term(s) Humans ; Odorants ; Olfaction Disorders/diagnosis ; Anosmia ; Reproducibility of Results ; Sensory Thresholds ; Smell
    Language English
    Publishing date 2024-01-10
    Publishing country England
    Document type Journal Article
    ZDB-ID 754122-3
    ISSN 1464-3553 ; 0379-864X
    ISSN (online) 1464-3553
    ISSN 0379-864X
    DOI 10.1093/chemse/bjae008
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Data Science-Based Analysis of Patient Subgroup Structures Suggest Effects of Rhinitis on All Chemosensory Perceptions in the Upper Airways

    Lötsch, J. / Hummel, T.

    2021  

    Abstract: Art. bjab001 ... Viral rhinitis contributes significantly to olfactory dysfunction, but it is unclear how many patients have other chemosensory symptoms in addition to olfactory loss. This was addressed in the present reanalysis of data previously ... ...

    Abstract Art. bjab001

    Viral rhinitis contributes significantly to olfactory dysfunction, but it is unclear how many patients have other chemosensory symptoms in addition to olfactory loss. This was addressed in the present reanalysis of data previously published in Pellegrino R, Walliczek-Dworschak U, Winter G, Hull D, Hummel T. 2017. Investigation of chemosensitivity during and after an acute cold. Int Forum Allergy Rhinol. 7(2):185-191, using unsupervised and supervised machine-learning methods. Fifty-eight patients with acute rhinitis and 59 healthy controls were assessed for orthonasal and retronasal olfactory function, taste, and intranasal trigeminal sensitivity. Unsupervised analysis showed that during rhinitis, clinical scores of olfactory function, expressed as threshold, discrimination, identification (TDI) values, were trimodally distributed. Two minor modes were separated from the main mode at TDI = 30.5, which corresponds to the established limit of hyposmia. This trimodal distribution was not observed after the rhinitis subsided. Olfactory function was not significantly impaired in 40% of all rhinitis patients, whereas it was transiently impaired in 59%. For this group, supervised machine-learning algorithms could be trained with information on retronasal olfactory function, gustatory function, and trigeminal sensitivity to assign patients to subgroups based on orthonasal olfactory function with a balanced classification accuracy of 64-65%. The ability to recognize patients with olfactory loss based on retronasal olfactory function as well as gustatory function and trigeminal sensitivity suggests in turn that these modalities are affected by rhinitis. However, the only modest accuracy at which this information allowed to reproduce the olfactory diagnosis indicated they are involved in the symptomatology of rhinitis to a lesser extent compared with the orthonasal olfactory function.

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    Keywords 571
    Subject code 610
    Language English
    Publishing country de
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: Euclidean distance-optimized data transformation for cluster analysis in biomedical data (EDOtrans).

    Ultsch, Alfred / Lötsch, Jörn

    BMC bioinformatics

    2022  Volume 23, Issue 1, Page(s) 233

    Abstract: Background: Data transformations are commonly used in bioinformatics data processing in the context of data projection and clustering. The most used Euclidean metric is not scale invariant and therefore occasionally inappropriate for complex, e.g., ... ...

    Abstract Background: Data transformations are commonly used in bioinformatics data processing in the context of data projection and clustering. The most used Euclidean metric is not scale invariant and therefore occasionally inappropriate for complex, e.g., multimodal distributed variables and may negatively affect the results of cluster analysis. Specifically, the squaring function in the definition of the Euclidean distance as the square root of the sum of squared differences between data points has the consequence that the value 1 implicitly defines a limit for distances within clusters versus distances between (inter-) clusters.
    Methods: The Euclidean distances within a standard normal distribution (N(0,1)) follow a N(0,[Formula: see text]) distribution. The EDO-transformation of a variable X is proposed as [Formula: see text] following modeling of the standard deviation s by a mixture of Gaussians and selecting the dominant modes via item categorization. The method was compared in artificial and biomedical datasets with clustering of untransformed data, z-transformed data, and the recently proposed pooled variable scaling.
    Results: A simulation study and applications to known real data examples showed that the proposed EDO scaling method is generally useful. The clustering results in terms of cluster accuracy, adjusted Rand index and Dunn's index outperformed the classical alternatives. Finally, the EDO transformation was applied to cluster a high-dimensional genomic dataset consisting of gene expression data for multiple samples of breast cancer tissues, and the proposed approach gave better results than classical methods and was compared with pooled variable scaling.
    Conclusions: For multivariate procedures of data analysis, it is proposed to use the EDO transformation as a better alternative to the established z-standardization, especially for nontrivially distributed data. The "EDOtrans" R package is available at https://cran.r-project.org/package=EDOtrans .
    MeSH term(s) Algorithms ; Cluster Analysis ; Computational Biology ; Genomics ; Normal Distribution
    Language English
    Publishing date 2022-06-16
    Publishing country England
    Document type Journal Article
    ZDB-ID 2041484-5
    ISSN 1471-2105 ; 1471-2105
    ISSN (online) 1471-2105
    ISSN 1471-2105
    DOI 10.1186/s12859-022-04769-w
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Robust Classification Using Posterior Probability Threshold Computation Followed by Voronoi Cell Based Class Assignment Circumventing Pitfalls of Bayesian Analysis of Biomedical Data.

    Ultsch, Alfred / Lötsch, Jörn

    International journal of molecular sciences

    2022  Volume 23, Issue 22

    Abstract: Bayesian inference is ubiquitous in science and widely used in biomedical research such as cell sorting or “omics” approaches, as well as in machine learning (ML), artificial neural networks, and “big data” applications. However, the calculation is not ... ...

    Abstract Bayesian inference is ubiquitous in science and widely used in biomedical research such as cell sorting or “omics” approaches, as well as in machine learning (ML), artificial neural networks, and “big data” applications. However, the calculation is not robust in regions of low evidence. In cases where one group has a lower mean but a higher variance than another group, new cases with larger values are implausibly assigned to the group with typically smaller values. An approach for a robust extension of Bayesian inference is proposed that proceeds in two main steps starting from the Bayesian posterior probabilities. First, cases with low evidence are labeled as “uncertain” class membership. The boundary for low probabilities of class assignment (threshold ε) is calculated using a computed ABC analysis as a data-based technique for item categorization. This leaves a number of cases with uncertain classification (p < ε). Second, cases with uncertain class membership are relabeled based on the distance to neighboring classified cases based on Voronoi cells. The approach is demonstrated on biomedical data typically analyzed with Bayesian statistics, such as flow cytometric data sets or biomarkers used in medical diagnostics, where it increased the class assignment accuracy by 1−10% depending on the data set. The proposed extension of the Bayesian inference of class membership can be used to obtain robust and plausible class assignments even for data at the extremes of the distribution and/or for which evidence is weak.
    MeSH term(s) Bayes Theorem ; Probability ; Uncertainty ; Big Data ; Biomedical Research
    Language English
    Publishing date 2022-11-15
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2019364-6
    ISSN 1422-0067 ; 1422-0067 ; 1661-6596
    ISSN (online) 1422-0067
    ISSN 1422-0067 ; 1661-6596
    DOI 10.3390/ijms232214081
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article: A data science-based analysis of seasonal patterns in outpatient presentations due to olfactory dysfunction.

    Lotsch, J / Hummel, T

    Rhinology

    2019  Volume 58, Issue 2, Page(s) 151–157

    Abstract: Background: Changes in human olfactory function throughout the year appear to be a common perception due to the seasonal oscillations in some etiologies associated with olfactory loss. However, longitudinal data from large cohorts were rarely analysed ... ...

    Abstract Background: Changes in human olfactory function throughout the year appear to be a common perception due to the seasonal oscillations in some etiologies associated with olfactory loss. However, longitudinal data from large cohorts were rarely analysed for temporal patterns of human olfaction apart from oscillations in specific etiologies of olfactory loss.
    Methods: Temporal patterns in the presentation of patients with olfactory disorders to a single centre were investigated as part of a cohort study. The time series analysis performed utilized a power spectrum analysis and an autoregressive integrated moving average (ARIMA) model in order to demonstrate repetitive fluctuations or trends in the monthly number of patients reporting from January 1999 to December 2017. The analyses additionally addressed temporal changes in the causes to which the olfactory disorder was attributed and in the degree of olfactory loss.
    Results: A cohort of 7,014 patients was included. Descriptive analysis showed that the presentation of olfactory disorders had seasonal variation, high in March, without a trend. Power spectrum analysis showed a general seasonality of the numbers of patients, without further pattern in the causes or the degree of olfactory dysfunction.
    Conclusions: The yearly periodicity in patient presentations at a specialized smell and taste clinic, was not readily attributable to seasonally changing medical causes of olfactory loss such as viral infections. This suggests that in addition to exploring the seasonality of olfactory etiologies, the changes in human olfactory acuity merit further assessments in longitudinal studies.
    MeSH term(s) Cohort Studies ; Data Science ; Humans ; Olfaction Disorders/epidemiology ; Outpatients ; Seasons ; Smell
    Language English
    Publishing date 2019-12-03
    Publishing country Netherlands
    Document type Journal Article
    ZDB-ID 80336-4
    ISSN 0300-0729
    ISSN 0300-0729
    DOI 10.4193/Rhin19.099
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: A perspective of randomness in a clinical test of olfactory performance.

    Lötsch, Jörn / Hummel, Thomas / Ultsch, Alfred

    Scientific reports

    2023  Volume 13, Issue 1, Page(s) 17923

    Abstract: Random walks describe stochastic processes characterized by a sequence of unpredictable changes in a random variable with no correlation to past changes. This report describes the random walk component of a clinical sensory test of olfactory performance. ...

    Abstract Random walks describe stochastic processes characterized by a sequence of unpredictable changes in a random variable with no correlation to past changes. This report describes the random walk component of a clinical sensory test of olfactory performance. The precise definition of this stochastic process allows the establishment of precise diagnostic cut-offs for the identification of olfactory loss. Within the Sniffin`Sticks olfactory test battery, odor discrimination (D) and odor identification (I) are assessed by four- and three-alternative forced-choice designs, respectively. Meanwhile, the odor threshold (T) test integrates a three-alternative forced-choice paradigm within a staircase paradigm with seven turning points. We explored this paradigm through computer simulations and provided a formal description. The odor threshold assessment test consists of two sequential components, the first of which sets the starting point for the second. Both parts can be characterized as biased random walks with significantly different probabilities of moving to higher (11%) or lower (89%) values. The initial odor concentration step for the first phase of the test and the length of the subsequent random walk in the second phase significantly affect the probability of randomly achieving high test scores. Changing the odor concentration from where the starting point determination for the second test part begins has raised the current cut-off for anosmia, represented as T + D + I < 16, from the 87th quantile of random test scores to the 97th quantile. Analogous findings are likely applicable to other sensory tests that use the staircase paradigm characterized as random walk.
    MeSH term(s) Humans ; Sensory Thresholds ; Smell ; Odorants ; Computer Simulation ; Electric Power Supplies ; Olfaction Disorders/diagnosis
    Language English
    Publishing date 2023-10-20
    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/s41598-023-45135-x
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Machine learning analysis predicts a person's sex based on mechanical but not thermal pain thresholds.

    Lötsch, Jörn / Mayer, Benjamin / Kringel, Dario

    Scientific reports

    2023  Volume 13, Issue 1, Page(s) 7332

    Abstract: Sex differences in pain perception have been extensively studied, but precision medicine applications such as sex-specific pain pharmacology have barely progressed beyond proof-of-concept. A data set of pain thresholds to mechanical (blunt and punctate ... ...

    Abstract Sex differences in pain perception have been extensively studied, but precision medicine applications such as sex-specific pain pharmacology have barely progressed beyond proof-of-concept. A data set of pain thresholds to mechanical (blunt and punctate pressure) and thermal (heat and cold) stimuli applied to non-sensitized and sensitized (capsaicin, menthol) forearm skin of 69 male and 56 female healthy volunteers was analyzed for data structures contingent with the prior sex structure using unsupervised and supervised approaches. A working hypothesis that the relevance of sex differences could be approached via reversibility of the association, i.e., sex should be identifiable from pain thresholds, was verified with trained machine learning algorithms that could infer a person's sex in a 20% validation sample not seen to the algorithms during training, with balanced accuracy of up to 79%. This was only possible with thresholds for mechanical stimuli, but not for thermal stimuli or sensitization responses, which were not sufficient to train an algorithm that could assign sex better than by guessing or when trained with nonsense (permuted) information. This enabled the translation to the molecular level of nociceptive targets that convert mechanical but not thermal information into signals interpreted as pain, which could eventually be used for pharmacological precision medicine approaches to pain. By exploiting a key feature of machine learning, which allows for the recognition of data structures and the reduction of information to the minimum relevant, experimental human pain data could be characterized in a way that incorporates "non" logic that could be translated directly to the molecular pharmacological level, pointing toward sex-specific precision medicine for pain.
    MeSH term(s) Humans ; Female ; Male ; Pain Threshold/physiology ; Hyperalgesia ; Pain Measurement ; Pain ; Capsaicin/pharmacology ; Hot Temperature ; Machine Learning
    Chemical Substances Capsaicin (S07O44R1ZM)
    Language English
    Publishing date 2023-05-05
    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/s41598-023-33337-2
    Database MEDical Literature Analysis and Retrieval System OnLINE

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