Real-time changepoint detection in a nonlinear expectile model

An online changepoint detection procedure based on conditional expectiles is introduced. The key contribution is threefold: nonlinearity of the underlying model improves the overall flexibility while a parametric form of the unknown regression function preserves a simple and straightforward interpretation; The conditional expectiles, well-known in econometrics for being the only coherent and elicitable risk measure, introduce additional robustness-especially with respect to asymmetric error distributions common in various types of data; The proposed statistical test is proved to be consistent and the distribution under the null hypothesis does not depend on the functional form of the underlying model nor the unknown parameters. Empirical properties of the proposed real-time changepoint detection test are investigated in a simulation study and a practical applicability is illustrated using the Covid-19 prevalence data from Prague.

Stressful Daylight: Differences in Diel Rhythmicity Between Albino and Pigmented Fish

In laboratory experiments, variously colored strains of animals, including those with albino phenotypes, are commonly used. The melanocortin theory suggests, however, that coloration phenotypes alter animal physiology and behavior. Animals with the albino phenotype show photoreceptor degradation associated with lowered visual accuracy, escape reactions, etc., presumably accompanied by prevailing nocturnal activity and lowered aggressiveness. This assumption was tested in small groups of albino and pigmented European catfish, Silurus glanis, during the diel cycle. The frequency of agonistic interactions was observed during mutual contests for shelters, and subsequently, blood plasma, brain, gill, and liver samples were collected to evaluate stress parameters. In an experimental arena with shelters, the light/dark rhythmicity of locomotor activity and aggressiveness of the two phenotypes were comparable; the peak was observed at night, and a lower peak was observed at dawn. In an experimental stream without shelters, the peak of locomotor activity occurred at night for only the pigmented phenotype. In the evaluation of 4 antioxidants and 1 oxidative stress indicator, representing a total of 15 indices, albino fish showed significant rhythmicity for 8 indices, whereas pigmented catfish showed significant rhythmicity for 5 indices. The production of blood stress parameters with the peak during the day occurred only in albino fish. A complex model was fitted with the aim of evaluating the links between behavioral and biochemical indices. Time periodicity was modeled using a sine wave and confirmed parallel courses of agonistic interactions in the catfish groups; the peak at dawn was associated with a 4.08-fold (conf. int. 3.53–4.7) increase in such interactions. The changes in glucose and superoxide dismutase concentrations varied with phenotype, while the effects of cortisol, lactate and catalase did not. In summary, the rhythmicity of locomotor activity and changes in the aggressiveness of catfish were influenced by shelter availability, and the effect of light-induced stress was more apparent in albino fish than in pigmented conspecific fish. The results suggested that laboratory-raised animals with pigmentation patterns naturally occurring in the wild show more reasonable values during experiments than those with an albino phenotype.

Can the One-Step Nucleic Acid Amplification method of lymph nodes examination make the staging of pulmonary tumours more precise?

INTRODUCTION

The aim of this article is to compare the sensitivity of detecting micrometastases in hilar and mediastinal lymph nodes in case of primary (non-small cell) and secondary (metastases of colorectal carcinoma) pulmonary tumours using standard histopathological examination with haematoxylin-eosin staining, immunohistochemistry examination with Anti-Cytokeratin 19 antibody and examination based on the One-Step Nucleic Acid Amplification method.

METHOD

During radical surgical treatment of primary non-small cell lung carcinoma and pulmonary metastases of colorectal carcinoma, hilar and mediastinal lymph nodes of 100 patients enrolled in the study in the period from 2015 to 2017 were extracted based on a standard classification. These lymph nodes were subsequently divided along the longitudinal axis into 4 identical parts where part one and three on the left were intended for examination based on the One-Step Nucleic Acid Amplification method, whereas parts two and four were subjected to histopathological examination. In evaluating the respective parts of the nodes by histological examination, the nodes were first examined by a standard procedure that involves haematoxylin-eosin staining, followed by immunohistochemistry examination with Anti-Cytokeratin 19 antibody. The One-Step Nucleic Acid Amplification method was performed in the kit supplied by Sysmex (Kobe, Japan) and is based on the detection of cytokeratin 19 mRNA (messenger ribonucleic acid) by reverse transcription coupled with isothermal amplification.

RESULTS

A total of 1,426 lymph nodes of the patients enrolled in the study were extracted and examined using the above mentioned methodology. In 78 patients (78%), identical results were obtained using haematoxylin-eosin staining, immunohistochemistry with Anti-Cytokeratin 19 and One-Step Nucleic Acid Amplification. Micrometastases in the lymph nodes using the One-Step Nucleic Acid Amplification method in the absence of the other methods were proven in 16 patients (16%). Only in 3 cases (3%), the examination by haematoxylin-eosin staining, or immunohistochemistry with Anti-Cytokeratin 19, was positive while One-Step Nucleic Acid Amplification was negative. The results obtained by immunohistochemistry with Anti-Cytokeratin 19 antibody were practically the same as those obtained by haematoxylin-eosin staining (97%).

CONCLUSION

The results of the study have demonstrated a higher percentage of metastases detected in hilar and mediastinal lymph nodes if the One-Step Nucleic Acid Amplification method of examination was used compared to haematoxylin-eosin staining and immunohistochemistry with Anti-Cytokeratin 19 antibody (upstaging in 16%). This shows that the examination of lymph nodes using the One-Step Nucleic Acid Amplification method can have a certain potential to make the pulmonary tumours staging more accurate. On the other hand, immunohistochemistry with Anti-Cytokeratin 19 antibody seems to be not so useful. However, it is necessary to prove this hypothesis in follow-up studies, or where applicable, in a larger cohort of patients. Another task is to ascertain, by careful patient monitoring, the influence of the micrometastases detected in their lymph nodes using the One-Step Nucleic Acid Amplification method on these patients' follow-up. Key words: lung cancer - lymph nodes - H&E - IHC CK19 - OSNA assay.

[One-Step Nucleic Acid Amplification method - what is the future of sentinel lymph node management?]

OBJECTIVE

The article summarizes current possibilities of usage of the One-Step Nucleic Acid Amplification method (OSNA) in the perioperative management of sentinel lymph nodes in oncologic surgery. The principle of this method is the detection of cytokeratin 19 (CK19) in the lymphatic tissue as a marker of the metastatic spread.

DESIGN

Review article.

SETTINGS

Department of Obstetrics and Gynaecology, University Hospital Pilsen, Faculty of Medicine in Pilsen, Charles University, Prague; Department of Biology, Faculty of Medicine in Pilsen, Charles University, Prague; Department of Immunochemistry, University Hospital Pilsen, Faculty of Medicine in Pilsen, Charles University, Prague; Sikl´s Department of Pathology, University Hospital Pilsen, Faculty of Medicine in Pilsen, Charles University, Prague.

METHODS

The review of the literature published until the end of April 2017 available on the PubMed database was performed. The official abbreviation OSNA and the full name of the method One-Step Nucleic Acid Amplification was used for search in this database.

CONCLUSION

The usage of the OSNA method with the detection of CK 19 in the sentinel lymph nodes as a marker of metastatic spread to the lymphatic tissue currently represents an acceptable form of perioperative sentinel lymph node management in patients with breast and colorectal cancer. Until now published data are pointing towards possible successful application of this method in sentinel lymph node management in patients with some other malignancies, such as thyroid carcinoma, gastric cancer, uterus cancer and head and neck cancer. More data is needed to establish this method also in those neoplasms.

[Predictive and prognostic factors of gastric cancer]

INTRODUCTION

Gastric cancer is a frequent malignant disease with poor prognosis. Most patients undergo only palliative treatment. Chemotherapy is another alternative but its effect differs in individual patients.

METHOD

This is retrospective study. We enrolled 54 patients (N=54) according to the inclusion criteria. We performed quantification of gene expression of selected genes and some microRNA from tumour tissue, which was used for the diagnosis. Statistical analysis of the data was performed.

RESULTS

We demonstrated a predictive value of gene expression of thynidylate synthase in tumour tissue for a therapeutic effect of chemotherapy based on 5-Fluorouracil or Capecitabine. At the same time, we demonstrated a predictive value of miR181, miR150, mir192 and miR342 microRNA levels from the tumour tissue. In addition, we succeeded to demonstrate a predictive value of miR221, miR224, miR520 and miR375 microRNA levels for a therapeutic effect of chemotherapy based on platinum derivates.

CONCLUSION

Thanks to the use of efficient therapy predictors, we can distinguish those patients who will profit from chemotherapy from patients where an effect cannot be expected. Thanks to personified oncology therapy the quality of life of some patients can be improved while reducing the costs of the therapy by avoiding inefficient chemotherapy. Only an early diagnosis of gastric cancer can reverse the adverse prognosis of patients with this disease.

KEY WORDS

gastric cancer - microRNA - prognostic markers - predictive markers.

Characterization of P19 cells during retinoic acid induced differentiation

The aim of our study was to characterize mouse embryonal carcinoma (EC) cells P19 in different stages of retinoic acid induced neurodifferentiation by two methods, immunocytochemistry and RT qPCR. The characterization of the cells is crucial before any transplantation into any model, e.g. in our case into the mouse brain with the aim to treat a neurodegenerative disease. Specific protein markers (MAP-2, OCT-4, FORSE-1) were detected by immunocytochemistry in the cell cultures. The mRNA expression levels of PAX-6, MASH-1, Brachyury, GATA-4 and AFP were determined by RT qPCR method. HPRT was used as a housekeeping gene. The degree of differentiation can be characterized by expression of analyzed genes. The presence of OCT-4 and FORSE-1 proteins in undifferentiated pluripotent cells and the presence of dendrite specific MAP-2 in neuroprogenitors was detected. The expression levels of PAX-6 and MASH-1 increased and expression of Brachyury decreased during the neurodifferentiation process. The expression levels of GATA-4 and AFP were the highest after induction of differentiation with retinoic acid. Detailed characterization of cells before transplantation experiments can contribute to better understanding of their effect.