Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

COMPARATIVE ANALYSIS OF TEMPERATURE EFFECTS ON FOUR KINDS OF FLEXURE HINGES

In order to reduce the temperature effects on compliant mechanisms,the comparative analysis of temperature effects on four kinds of typical flexure hinge with straight-beam,circular,elliptic and parabolic section is carried out,so that we can choose reasonablely the flexure hinge used to design compliant mechanisms. The flexure hinge is diviede into two variable cross-section beam elements,and the initial strain caused by temperature change is accounted into. The principle of minimum potential energy is applied to derive the thermal load vector and stiffness matrix of four kinds flexure hinge,and the mass matrix is obstained by employing Lagrange equation. And the mechanical model of the flexure hinges is obtained. The comparative analysis of the precision,thermal stress and thermal vibration of the compliant four-link mechanism is carried out based on the finite element model of the flexure hinge. The analysis results showed that the thermal errors of circular hinge is largest,and parabolic one,elliptic and straight-beam is smallest; The sequence of thermal stress from large to small is circular,elliptic,parabolic and straight-beam flexure hinge; The thermal vibration resonant frequency of the straight-beam hinge is minimum,the circular and elliptic one is second,parabolic is maximum,and it illustrated that the straight-beam hinge is more sussceptible to temperature changes. But the amplitude of the parabolic hinge at the resonant frequecy is maximum,and the thermal vibration is more larger

Preparation and biodistribution of novel 99mTc(CO)3-CNR complexes for myocardial imaging

We evaluated lipophilicity and biodistribution of a series of 99mTc(CO)3-ether isonitrile complexes todetermine whether different lipophilicity and structure of isonitrile ligands would improve the imaging properties ofthe radiopharmaceutical for the heart. Novel 99mTc(CO)3-MIBI analogs were prepared and analyzed by radio-HPLC,and their lipophilicity was determined. These new complexes could be bi- or tri-substituted in specified pHconditions like 99mTc(CO)3-MIBI. These new complexes exhibited low liver, lungs and blood uptake compared with[99mTc(CO)3(MIBI)3]+ though their heart uptake was not so high. Among these complexes, [99mTc(CO)3(EPI)2(OH2)]+showed higher target to non-target ratios at 5 and 30 min post-injection than that of [99mTc(CO)3(MIBI)3]+. Copyright# 2007 John Wiley & Sons, Lt

Sequence-dependent Effect of Triptolide with Gefitinib on the Proliferation and Apoptosis of Lung Adenocarcinoma Cell H1975

Background and objective Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) show promising therapeutic effects in patients with advanced non-small cell lung cancer (NSCLC). However, despite an initial response to TKIs treatment among responsive patients, most inevitably acquire resistance after a progression-free period of about 10 months. The percentage of T790M in TKI acquired-resistant patients in most studies is around 50%. The aim of this study is to assess the effects of the sequential administration of triptolide and geftinib on cell proliferation and apoptosis of lung adenocarcinoma cell H1975. Methods A MTT assay was used to measure cell proliferation. The potency of the sequential administration of triptolide and geftinib were determined by isobolograms and combination index (CI). Cell apoptosis and cycle distribution were detected by flow cytometry. The Hoechst 33258 method was used to observe the apoptotic morphology. Chemical colorimetric luminescence was used to measure the caspase activity. Results The results of isobolograms and CI showed that the sequential administration of triptolide following geftinib remarkably inhibited cell proliferation and cell apoptosis compared with other sequential administration models. The cycle distribution results indicated that sequential triptolide administration following geftinib blocked the cells in the G2/M phase but not in the G0/G1 phase. The activation of the Caspase-9/Caspase-3 cascade was mainly involved in the apoptotic pathway of lung adenocarcinoma cell H1975 in all sequential administration models. Conclusion The triptolide administration following geftinib might be a new therapeutic strategy for lung cancer with T790M mutation after having EGFR-TKIs resistance

ATTEMPT OF RADIOLABELING alpha-MSH ANALOG WITH F-18 AS MELANOMA TUMOR IMAGING AGENT

17th International Symposium on Radiopharmaceutical Science

Theranostic Small-Molecule Prodrug Conjugates for Targeted Delivery and Controlled Release of Toll-like Receptor 7 Agonists

We previously reported the design and synthesis of a small-molecule drug conjugate (SMDC) platform that demonstrated several advantages over antibody–drug conjugates (ADCs) in terms of in vivo pharmacokinetics, solid tumor penetration, definitive chemical structure, and adaptability for modular synthesis. Constructed on a tri-modal SMDC platform derived from 1,3,5-triazine (TZ) that consists of a targeting moiety (Lys-Urea-Glu) for prostate-specific membrane antigen (PSMA), here we report a novel class of chemically identical theranostic small-molecule prodrug conjugates (T-SMPDCs), [18/19F]F-TZ(PSMA)-LEGU-TLR7, for PSMA-targeted delivery and controlled release of toll-like receptor 7 (TLR7) agonists to elicit de novo immune response for cancer immunotherapy. In vitro competitive binding assay of [19F]F-TZ(PSMA)-LEGU-TLR7 showed that the chemical modification of Lys-Urea-Glu did not compromise its binding affinity to PSMA. Receptor-mediated cell internalization upon the PSMA binding of [18F]F-TZ(PSMA)-LEGU-TLR7 showed a time-dependent increase, indicative of targeted intracellular delivery of the theranostic prodrug conjugate. The designed controlled release of gardiquimod, a TLR7 agonist, was realized by a legumain cleavable linker. We further performed an in vivo PET/CT imaging study that showed significantly higher uptake of [18F]F-TZ(PSMA)-LEGU-TLR7 in PSMA+ PC3-PIP tumors (1.9 ± 0.4% ID/g) than in PSMA− PC3-Flu tumors (0.8 ± 0.3% ID/g) at 1 h post-injection. In addition, the conjugate showed a one-compartment kinetic profile and in vivo stability. Taken together, our proof-of-concept biological evaluation demonstrated the potential of our T-SMPDCs for cancer immunomodulatory therapies

A comparative study of trans- and cis-isomers of a bone-seeking agent, DO2A2P

Museo de Arquitectura en N

Cation exchange separation of 61Cu2+ from natCo targets and preparation of 61Cu-DOTA-HSA as a blood pool agent

An improved method for isolation of (61)Cu(2+) from a (nat)Co target using cation exchange was developed. (61)Cu(2+) was eluted from a cation exchange resin column by 0.2 M HCl with 90% acetone, while Co(2+) remained on the column. The whole separation process was completed within 50 min at more than 72% yield. The Co(2+) impurity level in (61)Cu(2+) solution was reduced to less than 0.1 ppm. Highly pure (61)Cu(2+) solution was then applied to prepare (61)Cu-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-human serum albumin (HSA) which showed good blood pool imaging properties