Cluster analysis of flow cytometric list mode data on a personal computer

A cluster analysis algorithm, dedicated to analysis of flow cytometric data is described. The algorithm is written in Pascal and implemented on an MS-DOS personal computer. It uses k-means, initialized with a large number of seed points, followed by a modified nearest neighbor technique to reduce the large number of subclusters. Thus we combine the advantage of the k-means (speed) with that of the nearest neighbor technique (accuracy). In order to achieve a rapid analysis, no complex data transformations such as principal components analysis were used. \ud Results of the cluster analysis on both real and artificial flow cytometric data are presented and discussed. The results show that it is possible to get very good cluster analysis partitions, which compare favorably with manually gated analysis in both time and in reliability, using a personal computer

A new principle of cell sorting by using selective electroporation in a modified flow cytometer

When a strong electric field pulse of a few microseconds is applied to biological cells, small pores are formed in the cell membranes; this process is called electroporation. At high field strengths and/or long pulse durations the membranes will be damaged permanently. This eventually leads to cell kill. \ud We have developed a modified flow cytometer in which one can electroporate individual cells selected by optical analysis. The first experiments with this flow cytometer were designed to use it as a damaging sorter; we used electric pulses of 10 s and resulting field strengths of 2.0 and 3.2 X 106 V/m to kill K562 cells and lymphocytes respectively. The hydrodynamically focused cells are first optically analyzed in the usual way in a square flow channel. At the end of this channel the cells are forced to flow through a small Coulter orifice, into a wider region. If optical analysis indicates that a cell is unwanted, the cell is killed by applying a strong electric field across the Coulter orifice. The wanted living cells can be subsequently separated from the dead cells and cell fragments by a method suitable for the particular application (e.g., centrifugation, cell growth, density gradient, etc.). \ud The results of these first experiments demonstrate that by using very simple equipment, sorting by selective killing with electric fields is possible at rates of 1,000 cells/s with a purity of the sorted fraction of 99.9%

Is rumination after bereavement linked with loss avoidance? : Evidence from eye-tracking

Funding: This research was funded by a Zon-MW TOP Grant of the Dutch Society for Scientific Research (NWO) under Grant number 91208009. Website: www.zonmw.nl. The funders had no role in the study design, data collection and analysis, decision to publish or preparation of the manuscript.Peer reviewedPublisher PD

A flow cytometric study of the membrane potential of natural killer and k562 cells during the cytotoxic process

This study demonstrates that it is possible to investigate the membrane potential of interacting cells during the cytotoxic process using flow cytometry. Changes in the membrane potential of NK and K562 cells, involved in a cell-mediated cytotoxic process, were studied by standard and slit-scan flow cytometry, using the membrane potential sensitive fluorescent probe DiBAC4(3). The NK cells were labeled with a membrane marker (TR-18 or DiI) prior to incubation with K562 cells and the conjugates that were formed could be identified on the basis of the membrane marker fluorescence and light scattering signals. With a slit-scan technique we measured the membrane potential of each cell in a conjugate separately. The results show that depolarization of the K562 cell occurs as a consequence of the cytotoxic activity of the NK cell. This depolarization appears to be an early sign of cell damage because the cell membrane still remains impermeable to propidium iodide. Our data also indicate that depolarization of the NK cell occurs as a result of its cytotoxic activity

Personality traits, depression and itch in patients with atopic dermatitis in an experimental setting : A regression analysis

It is known that itch is associated with psychological variables, but it is not known whether personality characteristics, depression or anxiety are predictors of experimentally induced itch in patients with atopic dermatitis (AD). In this study itch was induced in 27 patients with AD and 28 healthy controls by the presentation of an experimental video on crawling insects and skin diseases. Itch intensity was measured by self-ratings and by observing the number of scratch movements. Itch increase was determined by subtracting itch intensity induced by the experimental video from itch intensity induced by a control video. Psychological variables were assessed using validated questionnaires. In patients with AD, depression was a significant predictor of self-rated induced itch (corrected R2 = 0.175); while agreeableness and public self-consciousness were significant predictors of induced scratching (corrected R2 = 0.534). In healthy controls no associations were found. These results imply that a special group of patients with AD might benefit from certain psychological interventions

On the Classification and Reporting of Prolonged Grief:Assessment and Research Guidelines

Learning Objectives: After participating in this CME activity, the psychiatrist should be better able to • Explain the steps required for diagnosis of mental disorders in diagnostic handbooks. • Identify current procedures for classifying and reporting prolonged grief disorder. Abstract Prolonged grief disorder (PGD) was added to the 11th edition of the International Classification of Diseases in 2018 and to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders in its 2022 text revision. Thus, reporting and classifying PGD according to established guidelines has become fundamental for scientific research and clinical practice. Yet, PGD assessment instruments and criteria are still being developed and debated. The purpose of this article is to examine the adequacy of current procedures for classifying and reporting PGD in research and to suggest guidelines for future investigation and dissemination of knowledge. We outline the standard steps required for diagnosis and assessment of a mental disorder (notably, the administration of clinical interviews). In order to illustrate reporting about the presence/prevalence of PGD in recent scientific articles, we conducted a search of Scopus that identified 22 relevant articles published between 2019 and 2023. Our review of the literature shows that standard classification procedures are not (yet) followed. Prevalences of PGD are based on self-reported symptomatology, with rates derived from percentages of bereaved persons reaching a certain cutoff score on a questionnaire, without clinical interviewing. This likely results in systematic overestimation of prevalences. Nevertheless, the actual establishment of PGD prevalence was often stated in titles, abstracts, and results sections of articles. Further, the need for structured clinical interviews for diagnostic classification was frequently mentioned only among limitations in discussion sections - but was not highlighted. We conclude by providing guidelines for researching and reporting self-reported prolonged grief symptoms and the presence/prevalence of PGD.</p

On the Classification and Reporting of Prolonged Grief:Assessment and Research Guidelines

Learning Objectives: After participating in this CME activity, the psychiatrist should be better able to • Explain the steps required for diagnosis of mental disorders in diagnostic handbooks. • Identify current procedures for classifying and reporting prolonged grief disorder. Abstract Prolonged grief disorder (PGD) was added to the 11th edition of the International Classification of Diseases in 2018 and to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders in its 2022 text revision. Thus, reporting and classifying PGD according to established guidelines has become fundamental for scientific research and clinical practice. Yet, PGD assessment instruments and criteria are still being developed and debated. The purpose of this article is to examine the adequacy of current procedures for classifying and reporting PGD in research and to suggest guidelines for future investigation and dissemination of knowledge. We outline the standard steps required for diagnosis and assessment of a mental disorder (notably, the administration of clinical interviews). In order to illustrate reporting about the presence/prevalence of PGD in recent scientific articles, we conducted a search of Scopus that identified 22 relevant articles published between 2019 and 2023. Our review of the literature shows that standard classification procedures are not (yet) followed. Prevalences of PGD are based on self-reported symptomatology, with rates derived from percentages of bereaved persons reaching a certain cutoff score on a questionnaire, without clinical interviewing. This likely results in systematic overestimation of prevalences. Nevertheless, the actual establishment of PGD prevalence was often stated in titles, abstracts, and results sections of articles. Further, the need for structured clinical interviews for diagnostic classification was frequently mentioned only among limitations in discussion sections - but was not highlighted. We conclude by providing guidelines for researching and reporting self-reported prolonged grief symptoms and the presence/prevalence of PGD.</p

On the Classification and Reporting of Prolonged Grief:Assessment and Research Guidelines

Learning Objectives: After participating in this CME activity, the psychiatrist should be better able to • Explain the steps required for diagnosis of mental disorders in diagnostic handbooks. • Identify current procedures for classifying and reporting prolonged grief disorder. Abstract Prolonged grief disorder (PGD) was added to the 11th edition of the International Classification of Diseases in 2018 and to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders in its 2022 text revision. Thus, reporting and classifying PGD according to established guidelines has become fundamental for scientific research and clinical practice. Yet, PGD assessment instruments and criteria are still being developed and debated. The purpose of this article is to examine the adequacy of current procedures for classifying and reporting PGD in research and to suggest guidelines for future investigation and dissemination of knowledge. We outline the standard steps required for diagnosis and assessment of a mental disorder (notably, the administration of clinical interviews). In order to illustrate reporting about the presence/prevalence of PGD in recent scientific articles, we conducted a search of Scopus that identified 22 relevant articles published between 2019 and 2023. Our review of the literature shows that standard classification procedures are not (yet) followed. Prevalences of PGD are based on self-reported symptomatology, with rates derived from percentages of bereaved persons reaching a certain cutoff score on a questionnaire, without clinical interviewing. This likely results in systematic overestimation of prevalences. Nevertheless, the actual establishment of PGD prevalence was often stated in titles, abstracts, and results sections of articles. Further, the need for structured clinical interviews for diagnostic classification was frequently mentioned only among limitations in discussion sections - but was not highlighted. We conclude by providing guidelines for researching and reporting self-reported prolonged grief symptoms and the presence/prevalence of PGD.</p