Isolation,structure elucidation and biological activity of angucycline antibiotics from an epiphytic yew streptomycete

In the course of study of epiphytic microorganisms occurring on the surface of roots of Taxus baccata L. a new strain Streptomyces sp. AC113 was isolated. According to 16S ribosomal DNA‐based identification the new strain is 99% identical with Streptomyces flavidofuscus. This strain cultivated in an arginine glycerol medium produced three major metabolites identified as (–)‐8‐O ‐methyltetrangomycin ( 1 ), 8‐O ‐methyltetrangulol ( 2 ) and 8‐O ‐methyl‐7‐deoxo‐7‐hydroxytetrangomycin ( 3 ). The chemical structures of these angucyclines were elucidated by 1D and 2D NMR as well as by mass spectrometry. Isolated angucycline metabolites showed significant antimicrobial activity against Bacillus cereus and Listeria mocytogenes. Cytotoxic activities of compounds 1 , 2 and 3 against four cell lines (B16, HT‐29 and non – tumor V79, L929) were evaluated. Compound 3 was the most potent anticancer agents with IC₅₀ 0.054 μg/ml against cell line B16. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Potentialities of aberrantly methylated circulating DNA for diagnostics and post-treatment follow-up of lung cancer patients

To date, aberrant DNA methylation has been shown to be one of the most common and early causes of malignant cell transformation and tumors of different localizations, including lung cancer. Cancer cell-specific methylated DNA has been found in the blood of cancer patients, indicating that cell-free DNA circulating in the blood (cirDNA) is a convenient tumor-associated DNA marker that can be used as a minimally invasive diagnostic test. In the current study, we investigated the methylation status in blood samples of 32 healthy donors and 60 lung cancer patients before and after treatment with neoadjuvant chemotherapy followed by total tumor resection. Using quantitative methylation-specific PCR, we found that the index of methylation (IM), calculated as IM = 100 × [copy number of methylated/(copy number of methylated + unmethylated gene)], for the RASSF1A and RARB2 genes in the cirDNA isolated from blood plasma and cell-surface-bound cirDNA was elevated 2- to 3-fold in lung cancer patients compared with healthy donors. Random forest classification tree model based on these variables combined (RARB2 and RASSF1A IM in both plasma and cell-surface-bound cirDNA) lead to NSCLC patients’ and healthy subjects’ differentiation with 87% sensitivity and 75% specificity. An association of increased IM values with an advanced stage of non-small-cell lung cancer was found for RARB2 but not for RASSF1A. Chemotherapy and total tumor resection resulted in a significant decrease in the IM for RARB2 and RASSF1A, in both cirDNA fractions, comparable to the IM level of healthy subjects. Importantly, a rise in the IM for RARB2 was detected in patients within the follow-up period, which manifested in disease relapse at 9 months, confirmed with instrumental and pathologic methods. Our data indicate that quantitative analysis of the methylation status of the RARB2 and RASSF1A tumor suppressor genes in both cirDNA fractions is a useful tool for lung cancer diagnostics, evaluation of cancer treatment efficiency and post-treatment monitoring.     

Electrochemical sensing of blood proteins for mild traumatic brain injury (mTBI) diagnostics and prognostics: towards a point-of-care application

Traumatic Brain Injury (TBI) being one of the principal causes of death and acquired disability in the world imposes a large burden on the global economy. Mild TBI (mTBI) is particularly challenging to assess due to the frequent lack of well-pronounced post-injury symptoms. However, if left untreated mTBI (especially when repetitive) can lead to serious long-term implications such as cognitive and neuropathological disorders. Computer tomography and magnetic resonance imaging commonly used for TBI diagnostics require well-trained personnel, are costly, difficult to adapt for on-site measurements and are not always reliable in identifying small brain lesions. Thus, there is an increasing demand for sensitive point-of-care (POC) testing tools in order to aid mTBI diagnostics and prediction of long-term effects. Biomarker quantification in body fluids is a promising basis for POC measurements, even though establishing a clinically relevant mTBI biomarker panel remains a challenge. Actually, a minimally invasive, rapid and reliable multianalyte detection device would allow the efficient determination of injury biomarker release kinetics and thus support the preclinical evaluation and clinical validation of a proposed biomarker panel for future decentralized in vitro diagnostics. In this respect electrochemical biosensors have recently attracted great attention and the present article provides a critical study on the electrochemical protocols suggested in the literature for detection of mTBI-relevant protein biomarkers. The authors give an overview of the analytical approaches for transduction element functionalization, review recent technological advances and highlight the key challenges remaining in view of an eventual integration of the proposed concepts into POC diagnostic solutions.

Critical review on the electrochemical (EC) protocols suggested in the literature for the quantification of protein biomarkers relevant to mild traumatic brain injury (mTBI).     

Megakaryocyte progenitors in paroxysmal nocturnal haemoglobinuria are sensitive to complement

Abstract: We have investigated growth in vitro of bone marrow megakaryocytic progenitors (CFU-Mk) in 7 patients with paroxysmal nocturnal haemoglobinuria (PNH) to determine the sensitivity of CFU-Mk to complement. Bone marrow light density mononuclear cells were exposed to fresh or heat-inactivated AB human serum in the presence of medium or isotonic sucrose solution. We found that the proliferative activity of bone marrow CFU-Mk in PNH patients was significantly lower than in controls. In addition, the number of CFU-Mk in PNH bone marrow cells exposed to isotonic sucrose and complement was reduced to 25% of that in PNH cells exposed to isotonic sucrose without complement. In conclusion, our finding showed an increased sensitivity of CFU-Mk in PNH bone marrow cells to complement, supporting the hypothesis that the PNH defect is present at the level of CFU-Mk.     

Restricted MHC-peptide repertoire predisposes to autoimmunity

MHC molecules associated with autoimmunity possess known structural features that limit the repertoire of peptides that they can present. Such limitation gives a selective advantage to TCRs that rely on interaction with the MHC itself, rather than with the peptide residues. At the same time, negative selection is impaired because of the lack of negatively selecting peptide ligands. The combination of these factors may predispose to autoimmunity. We found that mice with an MHC class II-peptide repertoire reduced to a single complex demonstrated various autoimmune reactions. Transgenic mice bearing a TCR (MM14.4) cloned from such a mouse developed severe autoimmune dermatitis. Although MM14.4 originated from a CD4+ T cell, dermatitis was mediated by CD8+ T cells. It was established that MM14.4+ is a highly promiscuous TCR with dual MHC class I/MHC class II restriction. Furthermore, mice with a limited MHC-peptide repertoire selected elevated numbers of TCRs with dual MHC class I/MHC class II restriction, a likely source of autoreactivity. Our findings may help to explain the link between MHC class I responses that are involved in major autoimmune diseases and the well-established genetic linkage of these diseases with MHC class II.     

(+)-Usnic Acid and Its Derivatives as Inhibitors of a Wide Spectrum of SARS-CoV-2 Viruses

In order to test the antiviral activity, a series of usnic acid derivatives were synthesized, including new, previously undescribed compounds. The activity of the derivatives against three strains of SARS-CoV-2 virus was studied. To understand the mechanism of antiviral action, the inhibitory activity of the main protease of SARS-CoV-2 virus was studied using the developed model as well as the antiviral activity against the pseudoviral system with glycoprotein S of SARS-CoV-2 virus on its surface. It was shown that usnic acid exhibits activity against three strains of SARS-CoV-2 virus: Wuhan, Delta, and Omicron. Compounds 10 and 13 also showed high activity against the three strains. The performed biological studies and molecular modeling allowed us to assume that the derivatives of usnic acid bind in the N-terminal domain of the surface glycoprotein S at the binding site of the hemoglobin decay metabolite.     

Influence of resistance exercise intensity and metabolic stress on anabolic signaling and expression of myogenic genes in skeletal muscle

Introduction: We investigated the effect of resistance exercise intensity and exercise‐induced metabolic stress on the activation of anabolic signaling and expression of myogenic genes in skeletal muscle. Methods: Ten strength‐trained athletes performed high‐intensity [HI, 74% of 1‐repetition maximum (RM)], middle‐intensity (MI, 54% 1RM), or middle‐intensity (54% 1RM) no‐relaxation exercise (MIR). Kinase phosphorylation level and myogenic gene expression in muscle samples were evaluated before, 45 min, 5 h, and 20 h after exercise. Results: The lactate concentration in MI was approximately 2‐fold lower than in the 2 other sessions, and was highest in MIR. The phosphorylation level of extracellular kinase 1/2^{Thr202/Tyr204} after exercise was related to metabolic stress. Metabolic stress induced a decrease in myostatin mRNA expression, whereas mechano‐growth factor mRNA level depended on exercise intensity. Conclusions: This study demonstrates that both intensity and exercise‐induced metabolic stress can be manipulated to affect muscle anabolic signaling. Muscle Nerve 51: 434–442, 2015     

Focused open necrosectomy in necrotizing pancreatitis

Background

The control of sepsis is the primary goal of surgical intervention in patients with infected necrosis. Simple surgical approaches that are easy to reproduce may improve outcomes when specialists in endoscopy are not available. The aim of the present study was to describe the experience with a focused open necrosectomy (FON) in patients with infected necrosis.

Method

A prospective pilot study conducted to compare a semi-open/closed drainage laparotomy and FON with the assistance of peri-operative ultrasound. The incidence of sepsis, dynamics of C-reactive protein (CRP), intensive care unit (ICU)/hospital stay, complication rate and mortality were compared and analysed.

Results

From a total of 58 patients, 36 patients underwent a conventional open necrosectomy and 22 patients underwent FON. The latter method resulted in a faster resolution of sepsis and a significant decrease in mean CRP on Day 3 after FON, P = 0.001. Post-operative bleeding was in 1 versus 7 patients and the incidence of intestinal and pancreatic fistula was 2 versus 8 patients when comparing FON to the conventional approach. The median ICU stay was 11.6 versus 23 days and the hospital stay was significantly shorter, 57 versus 72 days, P = 0.024 when comparing FON versus the conventional group. One patient died in the FON group and seven patients died in the laparotomy group, P = 0.139.

Discussion

FON can be an alternative method to conventional open necrosectomy in patients with infected necrosis and unresolved sepsis.