We sequenced the genomes of 3,615 strains of serotype Emm protein 1 (M1) group A Streptococcus to unravel the nature and timing of molecular events contributing to the emergence, dissemination, and ...genetic diversification of an unusually virulent clone that now causes epidemic human infections worldwide. We discovered that the contemporary epidemic clone emerged in stepwise fashion from a precursor cell that first contained the phage encoding an extracellular DNase virulence factor (streptococcal DNase D2, SdaD2) and subsequently acquired the phage encoding the SpeA1 variant of the streptococcal pyrogenic exotoxin A superantigen. The SpeA2 toxin variant evolved from SpeA1 by a single-nucleotide change in the M1 progenitor strain before acquisition by horizontal gene transfer of a large chromosomal region encoding secreted toxins NAD ⁺-glycohydrolase and streptolysin O. Acquisition of this 36-kb region in the early 1980s into just one cell containing the phage-encoded sdaD2 and speA2 genes was the final major molecular event preceding the emergence and rapid intercontinental spread of the contemporary epidemic clone. Thus, we resolve a decades-old controversy about the type and sequence of genomic alterations that produced this explosive epidemic. Analysis of comprehensive, population-based contemporary invasive strains from seven countries identified strong patterns of temporal population structure. Compared with a preepidemic reference strain, the contemporary clone is significantly more virulent in nonhuman primate models of pharyngitis and necrotizing fasciitis. A key finding is that the molecular evolutionary events transpiring in just one bacterial cell ultimately have produced millions of human infections worldwide.
The increased expression of SIRT1 has recently been identified in numerous human tumors and a possible correlation with c-Myc oncogene has been proposed. However, it remains unclear whether SIRT1 ...functions as an oncogene or tumor suppressor. We sought to elucidate the role of SIRT1 in liver cancer under the influence of c-Myc and to determine the prognostic significance of SIRT1 and c-Myc expression in human hepatocellular carcinoma. The effect of either over-expression or knock down of SIRT1 on cell proliferation and survival was evaluated in both mouse and human liver cancer cells. Nicotinamide, an inhibitor of SIRT1, was also evaluated for its effects on liver tumorigenesis. The prognostic significance of the immunohistochemical detection of SIRT1 and c-Myc was evaluated in 154 hepatocellular carcinoma patients. SIRT1 and c-Myc regulate each other via a positive feedback loop and act synergistically to promote hepatocellular proliferation in both mice and human liver tumor cells. Tumor growth was significantly inhibited by nicotinamide in vivo and in vitro. In human hepatocellular carcinoma, SIRT1 expression positively correlated with c-Myc, Ki67 and p53 expression, as well as high á-fetoprotein level. Moreover, the expression of SIRT1, c-Myc and p53 were independent prognostic indicators of hepatocellular carcinoma. In conclusion, this study demonstrates that SIRT1 expression supports liver tumorigenesis and is closely correlated with oncogenic c-MYC expression. In addition, both SIRT1 and c-Myc may be useful prognostic indicators of hepatocellular carcinoma and SIRT1 targeted therapy may be beneficial in the treatment of hepatocellular carcinoma.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Thoracic outlet syndrome (TOS) is a group of disorders all having in common compression at the thoracic outlet. Three structures are at risk: the brachial plexus, the subclavian vein, and the ...subclavian artery, producing neurogenic (NTOS), venous (VTOS), and arterial (ATOS) thoracic outlet syndromes, respectively. Each of these three are separate entities, though they can coexist and possibly overlap. The treatment of NTOS, in particular, has been hampered by lack of data, which in turn is the result of inconsistent definitions and diagnosis, uncertainty with regard to treatment options, and lack of consistent outcome measures. The Committee has defined NTOS as being present when three of the following four criteria are present: signs and symptoms of pathology occurring at the thoracic outlet (pain and/or tenderness), signs and symptoms of nerve compression (distal neurologic changes, often worse with arms overhead or dangling), absence of other pathology potentially explaining the symptoms, and a positive response to a properly performed scalene muscle test injection. Reporting standards for workup, treatment, and assessment of results are presented, as are reporting standards for all phases of VTOS and ATOS. The overall goal is to produce consistency in diagnosis, description of treatment, and assessment of results, in turn then allowing more valuable data to be presented.
The hydrogen isotopes deuterium (D) and tritium (T) have become essential tools in chemistry, biology and medicine
. Beyond their widespread use in spectroscopy, mass spectrometry and mechanistic and ...pharmacokinetic studies, there has been considerable interest in incorporating deuterium into drug molecules
. Deutetrabenazine, a deuterated drug that is promising for the treatment of Huntington's disease
, was recently approved by the United States' Food and Drug Administration. The deuterium kinetic isotope effect, which compares the rate of a chemical reaction for a compound with that for its deuterated counterpart, can be substantial
. The strategic replacement of hydrogen with deuterium can affect both the rate of metabolism and the distribution of metabolites for a compound
, improving the efficacy and safety of a drug. The pharmacokinetics of a deuterated compound depends on the location(s) of deuterium. Although methods are available for deuterium incorporation at both early and late stages of the synthesis of a drug
, these processes are often unselective and the stereoisotopic purity can be difficult to measure
. Here we describe the preparation of stereoselectively deuterated building blocks for pharmaceutical research. As a proof of concept, we demonstrate a four-step conversion of benzene to cyclohexene with varying degrees of deuterium incorporation, via binding to a tungsten complex. Using different combinations of deuterated and proteated acid and hydride reagents, the deuterated positions on the cyclohexene ring can be controlled precisely. In total, 52 unique stereoisotopomers of cyclohexene are available, in the form of ten different isotopologues. This concept can be extended to prepare discrete stereoisotopomers of functionalized cyclohexenes. Such systematic methods for the preparation of pharmacologically active compounds as discrete stereoisotopomers could improve the pharmacological and toxicological properties of drugs and provide mechanistic information related to their distribution and metabolism in the body.
Medulloblastoma, the most common malignant pediatric brain tumor, often harbors MYC amplifications. Compared to high-grade gliomas, MYC-amplified medulloblastomas often show increased photoreceptor ...activity and arise in the presence of a functional ARF/p53 suppressor pathway. Here, we generate an immunocompetent transgenic mouse model with regulatable MYC that develop clonal tumors that molecularly resemble photoreceptor-positive Group 3 medulloblastoma. Compared to MYCN-expressing brain tumors driven from the same promoter, pronounced ARF silencing is present in our MYC-expressing model and in human medulloblastoma. While partial Arf suppression causes increased malignancy in MYCN-expressing tumors, complete Arf depletion promotes photoreceptor-negative high-grade glioma formation. Computational models and clinical data further identify drugs targeting MYC-driven tumors with a suppressed but functional ARF pathway. We show that the HSP90 inhibitor, Onalespib, significantly targets MYC-driven but not MYCN-driven tumors in an ARF-dependent manner. The treatment increases cell death in synergy with cisplatin and demonstrates potential for targeting MYC-driven medulloblastoma.
Specimen collection is an integral component of clinical research. Specimens from subjects with various stages of cancers or other conditions, as well as those without disease, are critical tools in ...the hunt for biomarkers, predictors, or tests that will detect serious diseases earlier or more readily than currently possible. Analytic methodologies evolve quickly. Access to high-quality specimens, collected and handled in standardized ways that minimize potential bias or confounding factors, is key to the “bench to bedside” aim of translational research. It is essential that standard operating procedures, “the how” of creating the repositories, be defined prospectively when designing clinical trials. Small differences in the processing or handling of a specimen can have dramatic effects in analytical reliability and reproducibility, especially when multiplex methods are used. A representative working group, Standard Operating Procedures Internal Working Group (SOPIWG), comprised of members from across Early Detection Research Network (EDRN) was formed to develop standard operating procedures (SOPs) for various types of specimens collected and managed for our biomarker discovery and validation work. This report presents our consensus on SOPs for the collection, processing, handling, and storage of serum and plasma for biomarker discovery and validation.
A supervised 12‐week intervention of time‐matched aerobic vs resistance versus concurrent exercise training was employed to investigate mode‐ and time course‐specific effects of exercise training in ...older adults. Community‐dwelling men and women (n = 84; M/F, 45/39; 69.3 ± 3.5 years; 26.4 ± 3.8 kg m−2) were randomly assigned (n = 21 each) to either non‐exercise control (CON), aerobic exercise only (AER), resistance exercise only (RES), or concurrent aerobic and resistance exercise (CEX). Training groups trained three times per week, each performing 72 minutes of active exercise time per week. Body composition, physical and cognitive function, and markers of metabolic health were assessed before (PRE), and after 6 (MID) and 12 (POST) weeks of exercise training. Hand‐grip strength, 1RM chest press, and arm LBM were improved by both RES and CEX, but not AER. Aerobic fitness increased in AER and RES, but not CEX. Cognitive function improved in all groups, but occurred earlier (ie, at MID) in AER. CEX improved gait speed and lower limb strength and reduced trunk fat compared to either AER or RES. Leg LBM was unchanged in any group. Temporal patterns were observed as early as 6 weeks of training (gait speed, upper and lower limb strength, aerobic fitness), whereas others were unchanged until 12 weeks (hand‐grip strength, timed up‐and‐go, sit‐to‐stand). Compared to either aerobic or resistance exercise training alone, concurrent exercise training is as efficacious for improving a range of health‐related parameters and is more efficacious for increasing gait speed and lower limb strength, and decreasing trunk fat in older adults.
Hepatic cancer is one of the most lethal cancers worldwide. Here, we report that the expression of Ca2+/calmodulin‐dependent protein kinase kinase 2 (CaMKK2) is significantly up‐regulated in ...hepatocellular carcinoma (HCC) and negatively correlated with HCC patient survival. The CaMKK2 protein is highly expressed in all eight hepatic cancer cell lines evaluated and is markedly up‐regulated relative to normal primary hepatocytes. Loss of CaMKK2 function is sufficient to inhibit liver cancer cell growth, and the growth defect resulting from loss of CaMKK2 can be rescued by ectopic expression of wild‐type CaMKK2 but not by kinase‐inactive mutants. Cellular ablation of CaMKK2 using RNA interference yields a gene signature that correlates with improvement in HCC patient survival, and ablation or pharmacological inhibition of CaMKK2 with STO‐609 impairs tumorigenicity of liver cancer cells in vivo. Moreover, CaMKK2 expression is up‐regulated in a time‐dependent manner in a carcinogen‐induced HCC mouse model, and STO‐609 treatment regresses hepatic tumor burden in this model. Mechanistically, CaMKK2 signals through Ca2+/calmodulin‐dependent protein kinase 4 (CaMKIV) to control liver cancer cell growth. Further analysis revealed that CaMKK2 serves as a scaffold to assemble CaMKIV with key components of the mammalian target of rapamycin/ribosomal protein S6 kinase, 70 kDa, pathway and thereby stimulate protein synthesis through protein phosphorylation. Conclusion: The CaMKK2/CaMKIV relay is an upstream regulator of the oncogenic mammalian target of rapamycin/ribosomal protein S6 kinase, 70 kDa, pathway, and the importance of this CaMKK2/CaMKIV axis in HCC growth is confirmed by the potent growth inhibitory effects of genetically or pharmacologically decreasing CaMKK2 activity; collectively, these findings suggest that CaMKK2 and CaMKIV may represent potential targets for hepatic cancer. (Hepatology 2015;62:505–520
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