Spectral cut-off regularizations for ill-posed linear models

International audienceThis paper deals with recovering an unknown vector β from the noisy data Y = Xβ + σξ, where X is a known n × p-matrix with n ≥ p and ξ is a standard white Gaussian noise. In order to estimate β, a spectral cutoff estimate β(m,Y) with a data-driven cutoff frequency m(Y) is used. The cutoff frequency is selected as a minimizer of the unbiased risk estimate of the mean square prediction error, i.e. m(Y) = arg min_{m}\| Y − X β (m, Y)\|^2 + 2σ^2 m. Assuming that β belongs to an ellipsoid W, we derive upper bounds for the maximal risk sup_{β∈W}E \|β[m(Y), Y] − β\|^2 and show that β[m(Y), Y] is a rate optimal minimax estimate over W

Ordered smoothers with exponential weighting

International audienceThe main goal in this paper is to propose a new approach to deriving oracle inequalities related to the exponential weighting method. The paper focuses on recovering an unknown vector from noisy data with the help of the family of ordered smoothers. The estimators within this family are aggregated using the exponential weighting method and the aim is to control the risk of the aggregated estimate. Based on natural probabilistic properties of the unbiased risk estimate, we derive new oracle inequalities for mean square risk and show that the exponential weighting permits to improve Kneip's oracle inequality

Steady states of lattice population models with immigration

In a lattice population model where individuals evolve as subcritical branching random walks subject to external immigration, the cumulants are estimated and the existence of the steady state is proved. The resulting dynamics are Lyapunov stable in that their qualitative behavior does not change under suitable perturbations of the main parameters of the model. An explicit formula of the limit distribution is derived in the solvable case of no birth. Monte Carlo simulation shows the limit distribution in the solvable case

MYCOBACTERIOSIS IN THE PRACTICE OF PULMONOLOGISTS AND PHTHISIOLOGISTS

Goal of the study: to investigate the frequency of mycobacteriosis in the practice of pulmonologists and phthisiologists.Materials and methods. The analysis included medical files of 156 patients with various non-specific respiratory diseases and tuberculosis who were examined in 2011-2014 and non-tuberculous mycobacteria were found in their sputum.Results of the study. pulmonary mycobacteriosis was diagnosed in 93 (59.6%) patients out of 156 who corresponded the criteria of American Thoracic Society and etiotropic treatment was prescribed. While detection of non-tuberculous mycobacteria in the other patients was considered as innidiation of respiratory tract by those mycobacteria in case of chronic non-specific pulmonary disease and/or tuberculosis. Mycobacterioses were treated with the relevance to drug susceptibility of the causative agent and there were numerous obstacles due to high frequency of adverse reactions

DETECTION AND DIFFERENTIATION OF NON-TUBERCULOUS MYCOBACTERIA AND M. TUBERCULOSIS COMPLEX BY REAL TIME PCR

Goal of the study: to define the design of primers and probes specific to DNA of non-tuberculous mycobacteria and evaluate their diagnostic value in case of simultaneous detection of non-tuberculous mycobacteria and M. tuberculosis complex by real time PCR.Materials and methods. Primer 3, Primer BLAST, Ugene Uni Pro were used to design primers and probes. Preliminary assessment of specificity and sensitivity of detection of non-tuberculous mycobacteria DNA was performed on cultures belonging to 18 types of non-tuberculous mycobacteria, 16 strains of M. tuberculosis complex and 14 types of microorganisms being none Mycobacterum. Analytic sensitivity was tested on 284 cultures of non-tuberculous mycobacteria and diagnostic sensitivity was tested on 124 sputum samples. The kit ofM-Sorb-Tub-Avtomat (ZAO Sintol) was used for DNA isolation. Cultures were subcultured on the liquid medium of Middlebrook 7H9 in Bactec MGIT 960. Cultures were identified with the use of standard microbiological techniques. Analysis of DNA isolated from cultures was performed by the reagent kit of GenoTypeCM/AS (Hain Lifescience, Germany).Results. 100% specificity and sensitivity of PCR was demonstrated in mycobacterial cultures and 100% specificity and 69-70% sensitivity was demonstrated in diagnostic material analysis

Endobronchial Ultrasound in Mediastinal Lymphadenopathy

Currently, endobronchial ultrasound dramatically changed diagnostic approaches for mediastinal lesions, both benign and malignant. Still there is a lack of data regarding the optimal anaesthesia, route of intubation, needle type, and specific clinical situations concerning EBUS in real clinical practice. A short, but clinically oriented, description of EBUS-TBNA and EUS-b-FNA techniques for mediastinal lesions is provided

Сравнительная молекулярно-генетическая характеристика культур Mycobacterium tuberculosis, выделенных в Европейской части Российской Федерации в 1998–2003 гг. и 2016–2021 гг.

The objective: to evaluate changes in detection frequency of Mycobacterium tuberculosis of the main phylogenetic lines with various genetic determinants of resistance to rifampicin, isoniazid and fluoroquinolones in 1998–2003 and 2016–2021.Subjects and Methods. 965 mycobacterial cultures were studied, those cultures were isolated from pulmonary tuberculosis patients in 1998–2003 and 2016–2021. The spoligotypes of isolated Mycobacterium tuberculosis cultures and presence of gene mutations associated with resistance to isoniazid, rifampicin, and fluoroquinolones were determined.Results. In 2016–2021 versus 1998–2003, the incidence of Beijing subline increased from 50,72% to 64,60%. Within Euro-American line, the detection frequency of subline LAM9 decreased (from 40,00% to 14,81%), while the detection frequency of sublineT1 increased (from 27,11% to 41,36%). Mycobacterium tuberculosis with MDR genotype rpoB531_Ser->Leu + katG315_Ser-> Thr [1] was selected. Mycobacterium tuberculosis with genotypic resistance to fluoroquinolones was detected only in cultures of 2016–2021, and Mycobacterium tuberculosis with preXDR genotype was significantly more common in Beijing subline compared to Euro-American line (21,67% vs. 3,73%, p <0,05).Цель исследования: оценить динамику частоты выявления МБТ основных филогенетических линий с различными генетическими детерминантами устойчивости к рифампицину, изониазиду и фторхинолонам в периоды 1998–2003 гг. и 2016–2021 гг.Материалы и методы. Исследовано 965 культур микобактерий, выделенных от больных туберкулезом легких в 1998–2003 гг. и 2016–2021 гг. Определены сполиготипы выделенных культур МБТ и наличие мутаций в генах, ассоциированных с устойчивостью к изониазиду, рифампицину и фторхинолонам.Результаты. В 2016–2021 гг. по сравнению с 1998–2003 гг. повысилась частота встречаемости МБТ Пекинской сублинии с 50,72% до 64,60%. В рамках Евро-Американской линии снизилась частота выявления МБТ сублинии LAM9 (с 40,00% до 14,81%) с повышением частоты выявления МБТ сублинии T1 (с 27,11% до 41,36%). Произошел отбор МБТ с МЛУ-генотипом rpoB531_Ser->Leu + katG315_Ser->Thr [1]. МБТ с генотипической устойчивостью к фторхинолонам были выявлены только в культурах 2016–2021 гг., причем МБТ с преШЛУ-генотипом достоверно чаще встречались у МБТ Пекинской сублинии по сравнению с МБТ Евро-Американской линии (21,67% против 3,73%, p<0,05)

АНАЛИЗ МУТАЦИЙ МИКОБАКТЕРИЙ ТУБЕРКУЛЕЗА, ОПРЕДЕЛЯЮЩИХ ИХ ЛЕКАРСТВЕННУЮ УСТОЙЧИВОСТЬ У БОЛЬНЫХ С НЕЛЕЧЕННЫМ ТУБЕРКУЛЕЗОМ ЛЕГКИХ ПРИ РАЗНОМ ВИЧ-СТАТУСЕ В СВЕРДЛОВСКОЙ ОБЛАСТИ

Goal of the study: to identify profile of mutations of tuberculous mycobacteria responsible for resistance to anti-tuberculosis drugs in HIV positive and HIV negative tuberculosis patients without prior history of treatment.Materials and methods. 165 strains of tuberculous mycobacteria from HIV positive patients and 166 strains of tuberculous mycobacteria from HIV negative patients were studied in Sverdlovsk Region (TB Dispensary, Yekaterinburg). Mutations in genes were identified using microchips of TB-BIOCHIP® and TB-BIOCHIP®-2 in compliance with the manufacturer's guidelines (OOO Biochip-IMB, Moscow).Results. It was observed that 85/165 (51.52%) strains isolated from HIV positive tuberculosis patients and 58/166 (34.94%) strains isolated from tuberculosis patients not associated with HIV possessed MDR genotype (p < 0.01). The majority of MDR strains had mutations in the 531th codon of rpoB (Ser→Leu) and 315th codon of katG (Ser→Thr) (64/85, 75.29% and 38/58, 65.52% respective the groups), resulting in the high level of resistance to rifampicin and isoniazid. Each group also had approximately equal ratio (11/165, 6.67% and 12/166, 7.23% respective the groups) of strains with genomic mutations defining the resistance to isoniazid, rifampicin and fluoruquinolones. No confident difference was found in mutation patterns of genome of tuberculous mycobacteria isolated from HIV positive and HIV negative tuberculosis patients. Цель исследования: определить спектр мутаций МБТ, ответственных за устойчивость к противотуберкулезным препаратам, у больных нелеченным туберкулезом, имеющим ВИЧ-позитивный или ВИЧ-негативный статус.Материалы и методы. Исследовано 165 штаммов МБТ от ВИЧ-позитивных и 166 штаммов МБТ от ВИЧ-негативных больных из Свердловской области (ГБУЗ СО «Противотуберкулезный диспансер», г. Екатеринбург). Определение мутаций в генах проводили на микрочипах «ТБ-БИОЧИП®» и «ТБ-БИОЧИП®-2» согласно инструкции изготовителя (ООО «Биочип-ИМБ», Москва).Результаты. Показано, что 85/165 (51,52%) штаммов, выделенных от больных туберкулезом с ВИЧ-инфекцией, и 58/166 (34,94%) штаммов от больных туберкулезом, не ассоциированным с ВИЧ-инфекцией, обладали МЛУ-генотипом (p < 0,01). Подавляющее большинство МЛУ-штаммов имели мутации в 531-м кодоне rpoB (Ser→Leu) и 315-м кодоне katG (Ser→Thr) (64/85, 75,29% и 38/58, 65,52% соответственно по группам), приводящие к высокому уровню резистентности к рифампицину и изониазиду. Кроме того, в каждой группе приблизительно в равном соотношении (11/165, 6,67% и 12/166, 7,23% соответственно по группам) встречались штаммы, несущие в геноме мутации, определяющие устойчивость к изониазиду, рифампицину и фторхинолонам. Достоверных отличий по спектру мутаций в геноме МБТ, выделенных от ВИЧ-позитивных и ВИЧ-негативных больных туберкулезом, не показано