Allele-specific activation, enzyme kinetics, and inhibitor sensitivities of EGFR exon 19 deletion mutations in lung cancer.

Oncogenic mutations within the epidermal growth factor receptor (EGFR) are found in 15 to 30% of all non-small-cell lung carcinomas. The term exon 19 deletion (ex19del) is collectively used to refer to more than 20 distinct genomic alterations within exon 19 that comprise the most common EGFR mutation subtype in lung cancer. Despite this heterogeneity, clinical treatment decisions are made irrespective of which EGFR ex19del variant is present within the tumor, and there is a paucity of information regarding how individual ex19del variants influence protein structure and function. Herein, we identified allele-specific functional differences among ex19del variants attributable to recurring sequence and structure motifs. We built all-atom structural models of 60 ex19del variants identified in patients and combined molecular dynamics simulations with biochemical and biophysical experiments to analyze three ex19del mutations (E746_A750, E746_S752 > V, and L747_A750 > P). We demonstrate that sequence variation in ex19del alters oncogenic cell growth, dimerization propensity, enzyme kinetics, and tyrosine kinase inhibitor (TKI) sensitivity. We show that in contrast to E746_A750 and E746_S752 > V, the L747_A750 > P variant forms highly active ligand-independent dimers. Enzyme kinetic analysis and TKI inhibition experiments suggest that E746_S752 > V and L747_A750 > P display reduced TKI sensitivity due to decreased adenosine 5'-triphosphate Km. Through these analyses, we propose an expanded framework for interpreting ex19del variants and considerations for therapeutic intervention.

Circulating Tumor DNA as a Biomarker of Radiographic Tumor Burden in SCLC.

INTRODUCTION: Blood-based next-generation sequencing assays of circulating tumor DNA (ctDNA) have the ability to detect tumor-associated mutations in patients with SCLC. We sought to characterize the relationship between ctDNA mean variant allele frequency (VAF) and radiographic total-body tumor volume (TV) in patients with SCLC. METHODS: We identified matched blood draws and computed tomography (CT) or positron emission tomography (PET) scans within a prospective SCLC blood banking cohort. We sequenced plasma using our previously developed 14-gene SCLC-specific ctDNA assay. Three-dimensional TV was determined from PET and CT scans using MIM software and reviewed by radiation oncologists. Univariate association and multivariate regression analyses were performed to evaluate the association between mean VAF and total-body TV. RESULTS: We analyzed 75 matched blood draws and CT or PET scans from 25 unique patients with SCLC. Univariate analysis revealed a positive association between mean VAF and total-body TV (Spearman's ρ = 0.292, p < 0.01), and when considering only treatment-naive and pretreatment patients (n = 11), there was an increase in the magnitude of association (ρ = 0.618, p = 0.048). The relationship remained significant when adjusting for treatment status and bone metastases (p = 0.046). In the subgroup of patients with TP53 variants, univariate analysis revealed a significant association (ρ = 0.762, p = 0.037) only when considering treatment-naive and pretreatment patients (n = 8). CONCLUSIONS: We observed a positive association between mean VAF and total-body TV in patients with SCLC, suggesting mean VAF may represent a dynamic biomarker of tumor burden that could be followed to monitor disease status.

Beyond Programmed Death-Ligand 1: B7-H6 Emerges as a Potential Immunotherapy Target in SCLC.

INTRODUCTION: The programmed death-ligand 1 (PD-L1) immune checkpoint inhibitors, atezolizumab and durvalumab, have received regulatory approval for the first-line treatment of patients with extensive-stage SCLC. Nevertheless, when used in combination with platinum-based chemotherapy, these PD-L1 inhibitors only improve overall survival by 2 to 3 months. This may be due to the observation that less than 20% of SCLC tumors express PD-L1 at greater than 1%. Evaluating the composition and abundance of checkpoint molecules in SCLC may identify molecules beyond PD-L1 that are amenable to therapeutic targeting. METHODS: We analyzed RNA-sequencing data from SCLC cell lines (n = 108) and primary tumor specimens (n = 81) for expression of 39 functionally validated inhibitory checkpoint ligands. Furthermore, we generated tissue microarrays containing SCLC cell lines and patient with SCLC specimens to confirm expression of these molecules by immunohistochemistry. We annotated patient outcomes data, including treatment response and overall survival. RESULTS: The checkpoint protein B7-H6 (NCR3LG1) exhibited increased protein expression relative to PD-L1 in cell lines and tumors (p < 0.05). Higher B7-H6 protein expression correlated with longer progression-free survival (p = 0.0368) and increased total immune infiltrates (CD45+) in patients. Furthermore, increased B7-H6 gene expression in SCLC tumors correlated with a decreased activated natural killer cell gene signature, suggesting a complex interplay between B7-H6 expression and immune signature in SCLC. CONCLUSIONS: We investigated 39 inhibitory checkpoint molecules in SCLC and found that B7-H6 is highly expressed and associated with progression-free survival. In addition, 26 of 39 immune checkpoint proteins in SCLC tumors were more abundantly expressed than PD-L1, indicating an urgent need to investigate additional checkpoint targets for therapy in addition to PD-L1.

Structure-function analysis of oncogenic EGFR Kinase Domain Duplication reveals insights into activation and a potential approach for therapeutic targeting.

Mechanistic understanding of oncogenic variants facilitates the development and optimization of treatment strategies. We recently identified in-frame, tandem duplication of EGFR exons 18 - 25, which causes EGFR Kinase Domain Duplication (EGFR-KDD). Here, we characterize the prevalence of ERBB family KDDs across multiple human cancers and evaluate the functional biochemistry of EGFR-KDD as it relates to pathogenesis and potential therapeutic intervention. We provide computational and experimental evidence that EGFR-KDD functions by forming asymmetric EGF-independent intra-molecular and EGF-dependent inter-molecular dimers. Time-resolved fluorescence microscopy and co-immunoprecipitation reveals EGFR-KDD can form ligand-dependent inter-molecular homo- and hetero-dimers/multimers. Furthermore, we show that inhibition of EGFR-KDD activity is maximally achieved by blocking both intra- and inter-molecular dimerization. Collectively, our findings define a previously unrecognized model of EGFR dimerization, providing important insights for the understanding of EGFR activation mechanisms and informing personalized treatment of patients with tumors harboring EGFR-KDD. Finally, we establish ERBB KDDs as recurrent oncogenic events in multiple cancers.

Bioactive constituents of Salvia przewalskii and the molecular mechanism of its antihypoxia effects determined using quantitative proteomics.

Context: Environmental hypobaric hypoxia induces several physiological or pathological responses in individuals in high-altitude regions. Salvia przewalskii Maxim (Labiatae) (SPM) is a traditional Chinese herbal medicine and has known antibacterial, antiviral, antioxidant, anti-thrombotic, and anti-depressant activities.Objective: This study examined the antihypoxia effects of SPM in vivo.Materials and methods: The dried and pulverised of SPM was extracted from root crude drug with 70% ethanol with ultrasound. Male Sprague-Dawley rats were divided into three groups (n = 10): normal group, hypoxia group (altitude of 4260 m), and hypoxia + SPM group (altitude of 4260 m, SPM of 1.0 g/kg/day). The experiment persisted for 4 weeks. The mean pulmonary arterial pressure (mPAP), hypoxia-inducible factor-1α (HIF-1α) mRNA, and lung pathology were analysed using pulmonary artery pressure recorder, quantitative polymerase chain reaction, and histopathological analysis. Moreover, the effects of SPM on lung proteomes during hypoxia were observed by a TMT-based proteomic approach.Results: Pre-treatment with SPM decreased mPAP (24.86%) and HIF-1α (31.24%), and attenuated the pathological changes in lung tissues. In addition, a total of 28 proteins were differentially expressed in lung of hypoxia + SPM group (fold change > ± 1.2 and p < 0.05). The differentially altered proteins were primarily associated with antioxidative stress, as evidenced by the downregulated expression of Adh7, Cyp2d1, Plod2, Selenow, ND3, and Fabp1, and fructose metabolism, as evidenced by the downregulated expression of Khk and Aldob.Discussion and conclusions: These results suggested that SPM is a promising drug for antihypoxia. The mechanism of action might be related to increasing antioxidant capacity and inhibiting fructose metabolism.

Magnesium lithospermate B ameliorates hypobaric hypoxia-induced pulmonary arterial hypertension by inhibiting endothelial-to-mesenchymal transition and its potential targets.

Pulmonary arterial hypertension (PAH) is a progressive disease characterized by vascular remodeling leading to elevation of pulmonary artery pressure, right ventricular hypertrophy, and death. Currently, there are no cure exists for PAH. Magnesium lithospermate B (MLB) is the major component of Salvia przewalskii water extracts with treating angina and cardiovascular damage, anti-inflammation, anti-oxidation and anti-apoptosis. However, the effects of MLB on PAH still unclear. This study we investigated the efficacy of MLB in the hypobaric hypoxia-induced rat model of PAH. The results showed that MLB relieved mean pulmonary arterial pressure (mPAP) and right ventricular hypertrophy index (RVHI). Meanwhile, MLB significantly reduced pulmonary vascular remodeling. Additionally, MLB inhibited hypobaric hypoxia-induced α-smooth muscle actin (α-SMA) expression, cell apoptosis, and α-SMA and von Willebrand factor (vWF) co-expression in lung, suggesting that MLB could inhibit hypobaric hypoxia-induced endothelial-to-mesenchymal transition (EndMT). Furthermore, after treatment with MLB, the expression of hypoxia inducible factor-1α (HIF-1α), nuclear factor-kappa B (NF-κB), monocyte chemoattractant protein-1 (MCP-1), proliferating cell nuclear antigen (PCNA), cyclin-dependent kinase 4 (CDK4), CyclinD1, RhoA, rho-associated protein kinase 1 (ROCK1) and ROCK2 was decreased. Further, CHK1, PIM1, STK6, LKHA4, PDE5A, BRAF1, PLK1, AKT1, PAK6, PAK7 and ELNE may be the potential targets of MLB. Taken together, our findings suggest that MLB ameliorates hypobaric hypoxia-induced PAH by inhibiting EndMT in rats, and has potential value in the preventment and treatment of PAH.

Blood-Based Surveillance Monitoring of Circulating Tumor DNA From Patients With SCLC Detects Disease Relapse and Predicts Death in Patients With Limited-Stage Disease.

INTRODUCTION: Most patients (70%) with limited-stage SCLC (LS-SCLC) who are treated with curative-intent therapy suffer disease relapse and cancer-related death. We evaluated circulating tumor DNA (ctDNA) as a predictor of disease relapse and death after definitive therapy in patients with LS-SCLC. METHODS: In our previous work, we developed a plasma-based ctDNA assay to sequence 14 genes (TP53, RB1, BRAF, KIT, NOTCH1-4, PIK3CA, PTEN, FGFR1, MYC, MYCL1, and MYCN) that are frequently mutated in SCLC. In this work, we evaluated 177 plasma samples from 23 patients with LS-SCLC who completed definitive chemoradiation (n = 21) or surgical resection (n = 2) and had an end-of-treatment blood collection (median 4 d, range 0-40 d from treatment completion) plus monthly surveillance blood sampling. Median overall survival (OS) and progression-free survival (PFS) were compared using a Wilcoxon test. RESULTS: The median OS among patients in whom we ever detected ctDNA after definitive treatment (n = 15) was 18.2 months compared with a median OS of greater than 48 months among patients in whom we never detected ctDNA after definitive treatment (n = 8; p = 0.081). The median PFS among patients in whom we ever detected ctDNA after definitive treatment was 9.1 months compared with a median PFS of greater than 48 months among patients in whom we never detected ctDNA after definitive treatment (p < 0.001). CONCLUSIONS: Detection of ctDNA in patients with LS-SCLC after curative-intent therapy predicts disease relapse and death. Prospective trials using ctDNA as an integral biomarker for therapeutic selection should be considered in SCLC.

Extract of Salvia przewalskii Repair Tissue Damage in Chronic Hypoxia Maybe through the RhoA-ROCK Signalling Pathway.

Salvia przewalskii Maxim is a traditional Chinese herbal medicine and is known to have antibacterial, antiviral, anti-oxidant, anti-thrombotic and anti-depressant properties. However, the major active components of S. przewalskii and its anti-hypoxic effects are still unclear. This study probed the major active component and anti-hypoxic activity of S. przewalskii. The major active components of S. przewalskii were detected by HPLC. The anti-hypoxic effects of S. przewalskii were detected in mice and a rat model of hypoxic preconditioning. The results showed that there are eight active components, including sodium danshensu, rosmarinic acid, lithospermic acid, salvianolic acid B, dihydrotanshinone I, cryptotanshinone, tanshinone I and tanshinone IIA, and each component showed a certain anti-hypoxic effect. Moreover, S. przewalskii enhanced anti-hypoxia in mice, which was manifested as prolonged survival time in acute hypoxic preconditioning and the amelioration of acute hypoxia-induced changes in the activity of superoxide dismutase (SOD) and lactate dehydrogenase (LDH). In addition, S. przewalskii also repaired tissue damage in chronic hypoxia by downregulating hypoxia inducible factor-1α (HIF-1α), proliferating cell nuclear antigen (PCNA), Bcl-2, CDK4, CyclinD1 and P27Kip1 and inhibiting pro-inflammatory cytokines and the RhoA-Rho-associated protein kinase (ROCK) signalling pathway. Our findings provide new insight into the anti-hypoxic effect of S. przewalskii as a promising agent for high-altitude pulmonary hypertension treatment.

On-target Resistance to the Mutant-Selective EGFR Inhibitor Osimertinib Can Develop in an Allele-Specific Manner Dependent on the Original EGFR-Activating Mutation.

PURPOSE: The third-generation EGFR inhibitor, osimertinib, is the first mutant-selective inhibitor that has received regulatory approval for the treatment of patients with EGFR-mutant lung cancer. Despite the development of highly selective third-generation inhibitors, acquired resistance remains a significant clinical challenge. Recently, we and others have identified a novel osimertinib resistance mutation, G724S, which was not predicted in in vitro screens. Here, we investigate how G724S confers resistance to osimertinib.Experimental Design: We combine structure-based predictive modeling of G724S in combination with the 2 most common EGFR-activating mutations, exon 19 deletion (Ex19Del) and L858R, with in vitro drug-response models and patient genomic profiling. RESULTS: Our simulations suggest that the G724S mutation selectively reduces osimertinib-binding affinity in the context of Ex19Del. Consistent with our simulations, cell lines transduced with Ex19Del/G724S demonstrate resistance to osimertinib, whereas cells transduced with L858R/G724S are sensitive to osimertinib. Subsequent clinical genomic profiling data further suggest G724S occurs with Ex19Del but not L858R. Furthermore, we demonstrate that Ex19Del/G724S retains sensitivity to afatinib, but not to erlotinib, suggesting a possible therapy for patients at the time of disease relapse. CONCLUSIONS: Altogether, these data suggest that G724S is an allele-specific resistance mutation emerging in the context of Ex19Del but not L858R. Our results fundamentally reframe the problem of targeted therapy resistance from one focused on the "drug-resistance mutation" pair to one focused on the "activating mutation-drug-resistance mutation" trio. This has broad implications across clinical oncology.

[Effects of Salvia przewalskii Maxim. on high-altitude pulmonary hypertension in rats and its mechanism].

OBJECTIVE: To investigate the interventive effects of Salvia przewalskii Maxim.(SPM)on high-altitude pulmonary hypertension(HAPH)in rats and possible mechanism. METHODS: The male SD rats were randomly divided into the control group, the hypoxia group and SPM(0.5 g/kg,1 g/kg and 2 g/kg) group. There were 14 rats in each group. The rats in control group were feed in Xining(with an altitude about 2 260 m), and the other group rats were all feed in Maduo county people's hospital(with an altitude about 4 260 m). The rats in SPM groups were treated with SPM at the doses of 0.5 g/kg,1 g/kg and 2 g/kg by gavage respectively (100 g/ml). The rats in control and the hypoxia groups were received equal volume of distilled water, once a day. After 4 weeks, the mean pulmonary artery pressure (mPAP) of rats was measured and the same part of lung tissue of each rat was collected and stored in liquid nitrogen. Then the relative mRNA expression levels of the proliferation cell nuclear antigen(PCNA), the cell cycle dependent kinase 4(CDK4), CyclinD1, RhoA, ROCK1, ROCK2 in lung tissues of each group rats were all tested by RT-PCR. RESULTS: Compared with the control group, the mPAP and the relative mRNA expression levels of PCNA, CDK4, CyclinD1, RhoA, ROCK1 and ROCK2 were increased significantly in the hypoxia group(P＜0.01). Compared with the hypoxia group, the mPAP and the relative mRNA expression levels of PCNA, CDK4, CyclinD1, RhoA, ROCK1 and ROCK2 in the lung tissues of the SPM group rats were all decreased significantly(P＜ 0.05 or P＜0.01). CONCLUSION: SPM can prevent the HAPH in rats, and the mechanisms may be related to the inhibition of the excessive proliferation of smooth muscle cells in pulmonary artery and the excessive activation of the RhoA/Rho kinase(ROCK) signaling pathway.

Longitudinal Cell-Free DNA Analysis in Patients with Small Cell Lung Cancer Reveals Dynamic Insights into Treatment Efficacy and Disease Relapse.

INTRODUCTION: Patients with SCLC have a poor prognosis and limited treatment options. Because access to longitudinal tumor samples is very limited in patients with this disease, we chose to focus our studies on the characterization of plasma cell-free DNA (cfDNA) for rapid, noninvasive monitoring of disease burden. METHODS: We developed a liquid biopsy assay that quantifies somatic variants in cfDNA. The assay detects single nucleotide variants, copy number alterations, and insertions or deletions in 14 genes that are frequently mutated in SCLC, including tumor protein p53 gene (TP53), retinoblastoma 1 gene (RB1), BRAF, KIT proto-oncogene receptor tyrosine kinase gene (KIT), notch 1 gene (NOTCH1), notch 2 gene (NOTCH2), notch 3 gene (NOTCH3), notch 4 gene (NOTCH4), phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha gene (PIK3CA), phosphatase and tensin homolog gene (PTEN), fibroblast growth factor receptor 1 gene (FGFR1), v-myc avian myelocytomatosis viral oncogene homolog gene (MYC), v-myc avian myelocytomatosis viral oncogene lung carcinoma derived homolog gene (MYCL1), and v-myc avian myelocytomatosis viral oncogene neuroblastoma derived homolog gene (MYCN). RESULTS: Over the course of 26 months of peripheral blood collection, we examined 140 plasma samples from 27 patients. We detected disease-associated mutations in 85% of patient samples with mutant allele frequencies ranging from 0.1% to 87%. In our cohort, 59% of the patients had extensive-stage disease, and the most common mutations occurred in TP53 (70%) and RB1 (52%). In addition to mutations in TP53 and RB1, we detected alterations in 10 additional genes in our patient population (PTEN, NOTCH1, NOTCH2, NOTCH3, NOTCH4, MYC, MYCL1, PIK3CA, KIT, and BRAF). The observed allele frequencies and copy number alterations tracked closely with treatment responses. Notably, in several cases analysis of cfDNA provided evidence of disease relapse before conventional imaging. CONCLUSIONS: These results suggest that liquid biopsies are readily applicable in patients with SCLC and can potentially provide improved monitoring of disease burden, depth of response to treatment, and timely warning of disease relapse in patients with this disease.

SFK/FAK Signaling Attenuates Osimertinib Efficacy in Both Drug-Sensitive and Drug-Resistant Models of EGFR-Mutant Lung Cancer.

Mutant-selective EGFR tyrosine kinase inhibitors (TKI), such as osimertinib, are active agents for the treatment of EGFR-mutant lung cancer. Specifically, these agents can overcome the effects of the T790M mutation, which mediates resistance to first- and second-generation EGFR TKI, and recent clinical trials have documented their efficacy in patients with EGFR-mutant lung cancer. Despite promising results, therapeutic efficacy is limited by the development of acquired resistance. Here we report that Src family kinases (SFK) and focal adhesion kinase (FAK) sustain AKT and MAPK pathway signaling under continuous EGFR inhibition in osimertinib-sensitive cells. Inhibiting either the MAPK pathway or the AKT pathway enhanced the effects of osimertinib. Combined SFK/FAK inhibition exhibited the most potent effects on growth inhibition, induction of apoptosis, and delay of acquired resistance. SFK family member YES1 was amplified in osimertinib-resistant EGFR-mutant tumor cells, the effects of which were overcome by combined treatment with osimertinib and SFK inhibitors. In conclusion, our data suggest that the concomitant inhibition of both SFK/FAK and EGFR may be a promising therapeutic strategy for EGFR-mutant lung cancer. Cancer Res; 77(11); 2990-3000. ©2017 AACR.

EGFR Fusions as Novel Therapeutic Targets in Lung Cancer.

UNLABELLED: Here, we report that novel epidermal growth factor receptor (EGFR) gene fusions comprising the N-terminal of EGFR linked to various fusion partners, most commonly RAD51, are recurrent in lung cancer. We describe five patients with metastatic lung cancer whose tumors harbored EGFR fusions, four of whom were treated with EGFR tyrosine kinase inhibitors (TKI) with documented antitumor responses. In vitro, EGFR-RAD51 fusions are oncogenic and can be therapeutically targeted with available EGFR TKIs and therapeutic antibodies. These results support the dependence of EGFR-rearranged tumors on EGFR-mediated signaling and suggest several therapeutic strategies for patients whose tumors harbor this novel alteration. SIGNIFICANCE: We report for the first time the identification and therapeutic targeting of EGFR C-terminal fusions in patients with lung cancer and document responses to the EGFR inhibitor erlotinib in 4 patients whose tumors harbored EGFR fusions. Findings from these studies will be immediately translatable to the clinic, as there are already several approved EGFR inhibitors. Cancer Discov; 6(6); 601-11. ©2016 AACR.See related commentary by Paik, p. 574This article is highlighted in the In This Issue feature, p. 561.

A novel Pseudomonas aeruginosa strain with an oprD mutation in relation to a nosocomial respiratory infection outbreak in an intensive care unit.

Seven imipenem-resistant Pseudomonas aeruginosa isolates were recovered from the sputum samples of pneumonia patients in southwestern China. They had identical antibiotic resistance patterns and indistinguishable pulsed-field gel electrophoresis profiles. Nucleotide sequence analysis revealed a 4-bp (AGTC) insertion in the oprD gene, resulting in a frameshift in the cognate open reading frame. These isolates became imipenem susceptible when the chromosomal oprD lesion was complemented, indicating that the 4-bp insertion in the oprD gene resulted in imipenem resistance.

Rationale for co-targeting IGF-1R and ALK in ALK fusion-positive lung cancer.

Crizotinib, a selective tyrosine kinase inhibitor (TKI), shows marked activity in patients whose lung cancers harbor fusions in the gene encoding anaplastic lymphoma receptor tyrosine kinase (ALK), but its efficacy is limited by variable primary responses and acquired resistance. In work arising from the clinical observation of a patient with ALK fusion-positive lung cancer who had an exceptional response to an insulin-like growth factor 1 receptor (IGF-1R)-specific antibody, we define a therapeutic synergism between ALK and IGF-1R inhibitors. Similar to IGF-1R, ALK fusion proteins bind to the adaptor insulin receptor substrate 1 (IRS-1), and IRS-1 knockdown enhances the antitumor effects of ALK inhibitors. In models of ALK TKI resistance, the IGF-1R pathway is activated, and combined ALK and IGF-1R inhibition improves therapeutic efficacy. Consistent with this finding, the levels of IGF-1R and IRS-1 are increased in biopsy samples from patients progressing on crizotinib monotherapy. Collectively these data support a role for the IGF-1R-IRS-1 pathway in both ALK TKI-sensitive and ALK TKI-resistant states and provide a biological rationale for further clinical development of dual ALK and IGF-1R inhibitors.

A microfluidic-enabled mechanical microcompressor for the immobilization of live single- and multi-cellular specimens.

A microcompressor is a precision mechanical device that flattens and immobilizes living cells and small organisms for optical microscopy, allowing enhanced visualization of sub-cellular structures and organelles. We have developed an easily fabricated device, which can be equipped with microfluidics, permitting the addition of media or chemicals during observation. This device can be used on both upright and inverted microscopes. The apparatus permits micrometer precision flattening for nondestructive immobilization of specimens as small as a bacterium, while also accommodating larger specimens, such as Caenorhabditis elegans, for long-term observations. The compressor mount is removable and allows easy specimen addition and recovery for later observation. Several customized specimen beds can be incorporated into the base. To demonstrate the capabilities of the device, we have imaged numerous cellular events in several protozoan species, in yeast cells, and in Drosophila melanogaster embryos. We have been able to document previously unreported events, and also perform photobleaching experiments, in conjugating Tetrahymena thermophila.

Differentiation of adipose-derived adult stem cells into epithelial-like stem cells.

Adipose-derived adult stem (ADAS) cells can be easily obtained in large quantities. Previous studies have suggested that all-trans-retinoic acid (ATRA) plays an important role in the differentiation of mesenchymal stem cells toward an epithelial lineage. In order to verify that ADAS-cells can differentiate into an epithelial lineage retaining most of the characteristics of stem cells, ADAS-cells were isolated and cultured. They were induced to differentiate toward an epithelial lineage in vitro. Differentiated epithelial cells were assayed as to whether they retain characteristics of stem cells by RT-PCR and cell cycle stage analysis, and were further induced to differentiate toward an osteogenic lineage. RT-PCR analysis revealed that no CK5, CK10 or CK19 mRNA was detected in ADAS-cells, CK19 but not CK5 or CK10 mRNA was detected in differentiated cells at passage 1, CK10 and CK19 expression but not CK5 mRNA was detected in differentiated cells at passage 10. After induction, the expression of CK19 was observed by immunofluorescent staining. Positive staining with alkaline phosphatase (ALP) and Von Kossa staining verified that differentiated epithelial cells still had potential to further differentiate toward an osteogenic lineage. These experiments provide proof that ADAS-cells can differentiate into an epithelial lineage retaining most of the characteristics of stem cells.

Comparative evaluation of Bruker Biotyper and BD Phoenix systems for identification of bacterial pathogens associated with urinary tract infections.

The Bruker Biotyper and BD Phoenix systems were evaluated for identification of 1,024 bacterial urinary tract isolates. The Biotyper and Phoenix systems correctly identified 99.9% and 99.5% to the genus level and 99.1% and 98.5% to the species level, respectively. Both systems provide reliable results, and the Biotyper system offers a rapid tool for urine bacterial isolate identification.

Molecular assays for the detection and characterization of respiratory viruses.

Patient care providers face an enormous challenge in diagnosing vial respiratory diseases because of similar clinical manifestations, as well as insensitivity and/or slow conventional laboratory detection methods. Nucleic acid-targeted molecular assays are playing critical roles in rapid detection, screening, and identification of respiratory viral pathogens due to their high sensitivity and specificity, short test turnaround time, as well as automatic and high-throughput processing. User-developed and commercial molecular methods have gradually been developed and become available for detection and identification of common viral pathogens causing respiratory tract infections. Incorporated with cutting edge techniques, these methods can be used to detect one or more pathogens in a single reaction tube qualitatively and quantitatively. Although the molecular assays have been increasingly used in the clinical setting, laboratorians and clinicians should well know the limitations of these molecular assays to wisely choose the right tests and correctly interpret test results.

Improved identification of yeast species directly from positive blood culture media by combining Sepsityper specimen processing and Microflex analysis with the matrix-assisted laser desorption ionization Biotyper system.

Current methods for identification of yeast from blood cultures may take several days after these microorganisms have been observed by Gram stain smears from positive blood cultures. We explored the use of a matrix-assisted laser desorption ionization (MALDI) Biotyper system in combination with Sepsityper specimen processing and Microflex analysis for improved detection and identification of yeast species directly from positive blood culture specimens demonstrating yeast-like organisms by Gram stain. The limit of detection of yeast species in blood culture medium was determined to be 5.9 × 10(5) CFU, with intra- and interstrain coefficients of variation of 1.8 to 3.6% and 2.9%, respectively. A total of 42 yeast-containing positive blood culture specimens were processed, and the identification results were compared to those obtained by routinely used phenotypic methods. Specimens with discrepant results between the Biotyper and phenotypic methods were identified on the basis of internal transcribed spacer region sequencing. The MALDI Biotyper system correctly identified the 42 specimens to species level, including 28 (66.7%) Candida albicans, 8 (19.0%) Candida parapsilosis, and 5 (11.9%) Candida tropicalis isolates and 1 (2.4%) Cryptococcus neoformans isolate. The entire procedure, from specimen extraction to final result reporting, can be completed within 1 h. Our data indicated that the Sepsityper specimen processing and Microflex analysis by the MALDI Biotyper system provide a rapid and reliable tool for yeast species identification directly from positive blood culture media.