A Natural-Language-Processing-Based Procedure for Generating Distractors for Multiple-Choice Questions.

One of the most challenging aspects of writing multiple-choice test questions is identifying plausible incorrect response options-i.e., distractors. To help with this task, a procedure is introduced that can mine existing item banks for potential distractors by considering the similarities between a new item's stem and answer and the stems and response options for items in the bank. This approach uses natural language processing to measure similarity and requires a substantial pool of items for constructing the generating model. The procedure is demonstrated with data from the United States Medical Licensing Examination (USMLE®). For about half the items in the study, at least one of the top three system-produced candidates matched a human-produced distractor exactly; and for about one quarter of the items, two of the top three candidates matched human-produced distractors. A study was conducted in which a sample of system-produced candidates were shown to 10 experienced item writers. Overall, participants thought about 81% of the candidates were on topic and 56% would help human item writers with the task of writing distractors.

Voltage-sensing optical recording: A method of choice for high-throughput assessment of cardiotropic effects.

INTRODUCTION: Voltage and calcium-sensing optical recording (VSOR and CSOR, respectively) from human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) have been validated for in vitro evaluation of cardiotropic effects of drugs. When compared to electrophysiological devices like microelectrode array, multi-well optical recordings present a lower sample rate that may limit their capacity to detect fast depolarization or propagation velocity alterations. Additionally, the respective sensitivities of VSOR and CSOR to different cardiac electrophysiological effects have not been compared in the same conditions. METHODS: FluoVolt and Cal520 dyes were used in 96 well format on hPSC-CMs to report sodium channel block by lidocaine and propagation slowing by the junctional uncoupler carbenoxolone at three recording frequencies (60, 120 and 200 Hz) as well as their sensitivity to early and late repolarization delay. RESULTS: Sodium channel block led to a dose-dependent decrease of the VSOR signal rising slope that was improved by an increased sampling frequency. In contrast, the CSOR signal rising slope was only decreased at the highest concentration with no influence from the sampling rate. A similar result was obtained with carbenoxolone. Early repolarization delay by Bay K8644 showed the same effects on VSOR and CSOR signal durations while repolarization slowing by dofetilide had a significantly stronger prolongating effect on the VSOR signal at the lowest concentration. DISCUSSION: VSOR showed a higher capacity to detect sodium channel block, propagation slowing and modest late repolarization delay than CSOR. Increasing the sampling rate improved the detection threshold of VSOR for excitability and conduction velocity alterations.

Validity of the Health Systems Science Examination: Relationship Between Examinee Performance and Time of Training.

The health systems science (HSS) framework articulates systems-relevant topics that medical trainees must learn to be prepared for physician practice. As new HSS-related curricula are developed, measures demonstrating appropriate levels of reliability and validity are needed. The authors describe a collaborative effort between a consortium of medical schools and the National Board of Medical Examiners to create a multiple-choice HSS examination in the areas of evidence-based medicine/population health, patient safety, quality improvement, and teamwork. Fifteen schools administered the 100-question examination through 2 academic years a total of 1887 times to 1837 first-time takers. Total test score mean was 67% (SD 11%). Total test reliability as measured by coefficient α was .83. This examination differentiated between medical students who completed the examination before, during, and after relevant training/instruction. This new HSS examination can support and inform the efforts of institutions as they integrate HSS-related content into their curricula.

Antitumor activity of a rhenium (I)-diselenoether complex in experimental models of human breast cancer.

Rhenium (I)-diselenother (Re-diselenoether) is a water soluble metal-based compound, combining one atom of rhenium and two atoms of selenium. This compound has been reported to exhibit marked activities against several solid tumor cell lines. We now disclose an improved synthesis of this complex. The Re-diselenoether showed a potent inhibitory effect on MDA-MB231 cell division in vitro, which lasted when the complex was no longer present in the culture. Re-diselenoether induced a remarkable reduction of the volume of the primitive breast tumors and of the pulmonary metastases without clinical signs of toxicity, in mice-bearing a MDA-MB231 Luc+ tumor, orthotopically transplanted, after a daily oral administration at the dose of 10 mg/kg/d. Interestingly, an antagonism was observed when cisplatin was administered as a single i.p. injection 1 week after the end of the Re-diselenoether administration. In an effort to gain insight of the mechanisms of action of Re-diselenoether complex, interaction with 9-methylguanine as a nucleic acid base model was studied. We have shown that Re-diselenoether gave both mono- and bis-guanine Re adducts, the species assumed to be responsible for the DNA intrastrand lesions.

Uptake and efflux of rhenium in cells exposed to rhenium diseleno-ether and tissue distribution of rhenium and selenium after rhenium diseleno-ether treatment in mice.

UNLABELLED: We proposed a new water-soluble rhenium diseleno-ether compound (with one atom of Re and two atoms of Se) and investigated the uptake of Re into the nucleus of malignant cells in culture exposed to the compound for 48 h and its efflux from the nucleus after a post-exposure period of 48 h, as DNA is the main target of Re. We also studied the distribution of both Re and Se in the main organs after an oral administration of 10 or 40 mg/kg Re diseleno-ether to mice for four weeks, five days-a-week. MATERIALS AND METHODS: Re and Se concentrations were assayed by inductively coupled plasma mass spectrometry (ICP-MS). Statistical analysis was performed using the Wilcoxon signed-rank test, comparing two related groups. RESULTS: We observed that Re was well incorporated into the nucleus of malignant cells in the most sensitive cells MCF-7, derived from human breast cancer, and that there was no efflux of Re. In contrast, in MCF-7 resistant cells (MCF-7 Mdr and MCF-7 R), A549 and HeLa cells, there was significant efflux of Re from the nucleus after the wash-out period. In mice, an important and dose-dependent uptake of both Re and Se was observed in the liver, with lower concentrations in kidneys. The lowest concentrations were observed in blood, lung, spleen and bones. There was a significant increase of Re concentrations in the blood, liver and kidney in mice treated with Re diseleno-ether at the dose of 40 mg/kg/24 h versus those treated at the dose of 10 mg/kg/24 h. There was a significant increase of Se concentrations in all tissues with the dose of Re diseleno-ether of 10 mg/kg/24 h versus controls, and a significant increase in the liver in mice treated with dose of Re diseleno-ether of 40 mg/kg/24h versus those treated with 10 mg/kg/24 h. CONCLUSION: We are the first to demonstrate that a compound combining Re and Se in a single molecule, is able to deliver Re and Se to the organism via an oral route, for cancer treatment.

Combination of three metals for the treatment of cancer: gallium, rhenium and platinum. 1. Determination of the optimal schedule of treatment.

Platinum is well known for its anticancer activity, firstly used as cis-diaminedichloroplatinum (II) (CDDP), with a wide range of activity. Its main mechanism of action involves its binding to DNA. Gallium, another metal, has also demonstrated apoptotic effects on malignant cells, but through interaction with targets other than DNA, such as the membrane, cytoskeleton and proteasome, and on enzyme activities. An antitumor synergism between CDDP and both gallium and rhenium compounds has been demonstrated. For these reasons, we proposed to combine these three metals and to determine at which doses each compound could be administered without major toxicity. CDDP, tetrakis(1-octanol) tris(5-aminosalicylate)gallium(III), and a diseleno-ether rhenium(I) complex were used in this experimental study in breast cancer MCF-7 tumor-bearing mice. CDDP was administered intraperitoneally (i.p.) twice a week at the dose of 3 mg/kg. Tetrakis(1-octanol) tris(5-aminosalicylate) gallium (III) and rhenium(I) diseleno-ether complexes were administered orally, daily, five days a week for three weeks, at doses ranging from 20 to 100 mg/kg for the gallium compound and from 10 to 50 mg/kg for the rhenium compound. Doses of 10 mg/kg of rhenium(I) diseleno-ether, and 100 mg/kg of the salicylate gallium compound, in combination with CDDP induced a significant decrease of 50% of the tumor volume, by comparison with the control group. In contrast, the decrease of the tumor volume in mice treated by CDDP alone was less than 25%. Changes in the sequence of administration of the three metals will be discussed to improve the therapeutic index.

Developing an in-training examination for fellows: the experience of the American Society of Clinical Oncology.

The American Society of Clinical Oncology (ASCO) developed its own test -- the Medical Oncology In-Training Examination (MedOnc ITE) -- as a tool to assess trainees' knowledge of the clinical oncology subspecialty, establish consistency in educational standards across training programs, identify areas of strength and weakness in individual programs, and stimulate intraprogrammatic reading and discussion. The Accreditation Council for Graduate Medical Education Outcome Project provided additional incentive for ASCO to develop an ITE. The examination was developed in 4 years. The concept of the examination and the budget were approved by the ASCO governing board. The National Board of Medical Examiners was selected to work with ASCO. Fellowship programs were contacted to determine if they had the information technology support to hold the examination. A blueprint for the examination was developed. The test format, including the number of questions and the selection of case-based single best answers, was determined. Physician volunteers to write the questions were solicited from among program directors, various ASCO committees, and disease experts. A workshop was held to teach volunteers how to write proper case-based questions. From this pool, a smaller group of physicians was selected to develop the test and review all test questions. The final examination was developed and administered in February 2008, with scores provided to fellows and program directors in April 2008. Feedback received after the examination will be helpful for developing future MedOnc ITEs. The process ASCO went through to develop the MedOnc ITE serves as a model for other subspecialties interested in developing their own ITEs.

Inhibitors of strand transfer that prevent integration and inhibit human T-cell leukemia virus type 1 early replication.

The replication of the retrovirus human T-cell leukemia virus type 1 (HTLV-1) is linked to the development of lymphoid malignancies and inflammatory diseases. Data from in vitro, ex vivo, and in vivo studies have revealed that no specific treatment can prevent or block HTLV-1 replication and therefore that there is no therapy for the prevention and/or treatment of HTLV-1-associated diseases in infected individuals. HTLV-1 and human immunodeficiency virus type 1 (HIV-1) integrases, the enzymes that specifically catalyze the integration of these retroviruses in host cell DNA, share important structural properties, suggesting that compounds that inhibit HIV-1 integration could also inhibit HTLV-1 integration. We developed quantitative assays to test, in vitro and ex vivo, the efficiencies of styrylquinolines and diketo acids, the two main classes of HIV-1 integrase inhibitors. The compounds were tested in vitro in an HTLV-1 strand-transfer reaction and ex vivo by infection of fresh peripheral blood lymphocytes with lethally irradiated HTLV-1-positive cells. In vitro, four styrylquinoline compounds and two diketo acid compounds significantly inhibited HTLV-1 integration in a dose-dependent manner. All compounds active in vitro decreased cell proliferation ex vivo, although at low concentrations; they also dramatically decreased both normalized proviral loads and the number of integration events during experimental ex vivo primary infection. Accordingly, diketo acids and styrylquinolines are the first drugs that produce a specific negative effect on HTLV-1 replication in vitro and ex vivo, suggesting their potential efficiency for the prevention and treatment of HTLV-1-associated diseases.

Experimental/theoretical electrostatic properties of a styrylquinoline-type HIV-1 integrase inhibitor and its progenitors.

We have established that polyhydroxylated styrylquinolines are potent inhibitors of HIV-1 integrase (IN). Among them, we have identified (E)-8-hydroxy-2-[2-(4,5-dihydroxy-3-methoxyphenyl)-ethenyl]-7-quinolinecarboxylic acid (1) as a promising lead. Previous molecular dynamics simulations and docking procedures have shown that the inhibitory activity involves one or two metal cations (Mg2+), which are present in the vicinity of the active center of the enzyme. However, such methods are generally based on a force-field approach and still remain not as reliable as ab initio calculations with extended basis sets on the whole system. To go further in this area, the aim of the present study was to evaluate the predictive ability of the electron density and electrostatic properties in the structure-activity relationships of this class of HIV-1 antiviral drugs. The electron properties of the two chemical progenitors of 1 were derived from both high-resolution X-ray diffraction experiments and ab initio calculations. The twinning phenomenon and solvent disorder were observed during the crystal structure determination of 1. Molecule 1 exhibits a planar s-trans conformation, and a zwitterionic form in the crystalline state is obtained. This geometry was used for ab initio calculations, which were performed to characterize the electronic properties of 1. The electron densities, electrostatic potentials, and atomic charges of 1 and its progenitors are here compared and analyzed. The experimental and theoretical deformation density bond peaks are very comparable for the two progenitors. However, the experimental electrostatic potential is strongly affected by the crystal field and cannot straightforwardly be used as a predictive index. The weak difference in the theoretical electron densities between 1 and its progenitors reveals that each component of 1 conserves its intrinsic properties, an assumption reinforced by a 13C NMR study. This is also shown through an excellent correlation of the atomic charges for the common fragments. The electrostatic potential minima in zwitterionic and nonzwitterionic forms of 1 are discussed in relation with the localization of possible metal chelation sites.

New HIV-1 replication inhibitors of the styryquinoline class bearing aroyl/acyl groups at the C-7 position: synthesis and biological activity.

Novel variants of HIV-1 replication inhibitors of the styrylquinoline class harboring aroyl/acyl group at the C-7 position have been synthesized. In sharp contrast with styrylquinolines bearing a carboxylic acid group at C-7, these compounds proved to be inactive toward HIV-1 integrase in in vitro assays.

A methodology to study intracellular distribution of nanoparticles in brain endothelial cells.

Cell internalisation and intracellular distribution of PEG-coated polyhexadecylcyanoacrylate (PEG-PHDCA) nanoparticles in rat brain endothelial cells (RBEC) have been investigated. A cell fractionation method has been developed based on the selective permeabilisation of RBEC plasma membrane by digitonin. By interacting with membrane cholesterol, digitonin creates pores allowing the release of soluble and diffusible species outside the cell. The selectivity of plasma membrane permeabilisation was controlled by using compartment markers such as lactate dehydrogenase (LDH) for cytoplasm and cathepsin B for lysosomes. An optimal digitonin concentration of 0.003% (w/v) has been identified to induce a pattern of membrane permeabilisation corresponding to the extraction of 72% LDH and less than 15% of Cathepsin B. Membrane permeabilisation at this digitonin concentration allows one to distinguish between the cell cytoplasm and its endo/lysosomal fraction. This methodology was applied to investigate the intracellular distribution of the nanoparticles after their incubation with the RBEC. The results showed that PEG-PHDCA nanoparticles were able to be internalised to a higher extent than PHDCA nanoparticles (after 20 min incubation). Additionally, these nanoparticles displayed different patterns of intracellular capture, depending on their specific surface composition: PEG-PHDCA nanoparticles were 48% in the plasma membrane, 24% in the cytoplasm, 20% in vesicular compartments and 8% associated with the fraction of the nucleus, the cytoskeleton and caveolae suggesting that PEG-PHDCA nanoparticle uptake by RBEC is specific and presumably due to endocytosis. Confocal microscopy studies confirmed the cellular uptake of PEG-PHDCA nanoparticles.

7-Carboxylato-8-hydroxy-2-methylquinolinium monohydrate and 7-carboxy-8-hydroxy-2-methylquinolinium chloride monohydrate at 100 K.

Both 7-carboxylato-8-hydroxy-2-methylquinolinium monohydrate, C11H9NO3.H2O, (I), and 7-carboxy-8-hydroxy-2-methylquinolinium chloride monohydrate, C11H10NO3+.Cl-.H2O, (II), crystallize in the centrosymmetric P-1 space group. Both compounds display an intramolecular O-H...O hydrogen bond involving the hydroxy group; this hydrogen bond is stronger in (I) due to its zwitterionic character [O...O = 2.4449 (11) A in (I) and 2.5881 (12) A in (II)]. In both crystal structures, the HN+ group participates in the stabilization of the structure via intermolecular hydrogen bonds with water molecules [N...O = 2.7450 (12) A in (I) and 2.8025 (14) A in (II)]. In compound (II), a hydrogen-bond network connects the Cl- anion to the carboxylic acid group [Cl...O = 2.9641 (11) A] and to two water molecules [Cl...O = 3.1485 (10) and 3.2744 (10) A].

Negative preclinical results with stealth nanospheres-encapsulated Doxorubicin in an orthotopic murine brain tumor model.

Previous results have shown that PEG-coated poly(hexadecylcyanoacrylate) (PEG-PHDCA) nanospheres displayed a significant accumulation within an orthotopic 9L gliosarcoma model, after i.v. administration to rats. Hence, the aim of the present study was to evaluate in the same model the pre-clinical efficacy of this carrier when loaded with Doxorubicin, an anticancer drug which poorly distributes in the CNS. Free and nanospheres-encapsulated Doxorubicin were administered with a multiple dose treatment. Their maximum tolerated dose (MTD) and increase in life span were respectively assessed in healthy and intracranially 9L-bearing rats. A comparative biodistribution study of Doxorubicin-loaded and unloaded PEG-PHDCA nanospheres was also performed in the tumor-bearing group. The results showed that the cumulative MTD of nanoparticulate doxorubicin was 1.5 times higher than this of free Doxorubicin. Nevertheless, encapsulated Doxorubicin was unable to elicit a better therapeutic response in the 9L gliosarcoma. Biodistribution study revealed that the Doxorubicin-loaded nanospheres accumulated to a 2.5-fold lesser extent in the 9L tumor as compared to the unloaded nanospheres and that they were mainly localized in the lungs and the spleen. Such a typical profile indicated aggregation with plasma proteins as a consequence of the positive surface charge of these loaded particles; this ionic interaction resulting from drug encapsulation was mainly responsible for 9L treatment failure.

Asymmetric Michael reaction involving chiral imines/secondary enamines: stereocontrolled synthesis of 2,2-disubstituted tetrahydrothiophen-3-ones.

[reaction: see text] The asymmetric Michael reaction involving a chiral imine derived from 2-methyltetrahydrothiophenone-3-one and enantiopure (R)-1-phenylethylamine with a variety of electrophilic alkenes furnished 2,2-disubstituted tetrahydrothiophenone-3-ones with good yields and excellent stereoselectivity.

Crystallographic/experimental electron density characterizations and reactions with nucleophiles of beta-enaminonitriles possessing a pyrrolobenzazepine core.

In connection with a total synthesis of cephalotaxine (1a), we have examined the addition of various nucleophilic reagents to [ABC] subunits 2 and 7 possessing a pyrrolobenzazepine core. In fact, this reaction implicates invariably the carbonyl group of 2. Regarding the reaction of 7 with nucleophiles, the most striking aspect is the complete lack of reactivity of the enaminonitrile moiety. For instance, the condensation of 7 with methylmagnesium bromide involves exclusively the cleavage of the dioxole ring, yielding regioisomers 9 and 10. With the aim of understanding the unexpected reactivity of 2 and 7 toward nucleophiles, crystallographic studies of 2 and 7 and an experimental electron density determination of 7 were carried out. The marked reactivity of the carbonyl group of 2 was interpreted by invoking the weakness of the amide resonance, due to a pronounced delocalization of the N(9) lone pair over the enaminonitrile moiety. The electron density study of 7 reveals this electron delocalization along the enaminonitrile fragment, highlighted and quantified through the bond geometries, topological indicators, and atomic charges, a phenomenon that is responsible for the failure of the addition of nucleophilic species.

Styrylquinolines, integrase inhibitors acting prior to integration: a new mechanism of action for anti-integrase agents.

We have previously shown that styrylquinolines (SQLs) are integrase inhibitors in vitro. They compete with the long terminal repeat substrate for integrase. Here, we describe the cellular mode of action of these molecules. We show that SQLs do not interfere with virus entry. In fact, concentrations of up to 20 times the 50% inhibitory concentration did not inhibit cell-to-cell fusion or affect the interaction between GP120 and CD4 in vitro. Moreover, the pseudotype of the retrovirus envelope did not affect drug activity. Quantitative reverse transcription PCR experiments showed that SQLs do not inhibit the entry of the genomic RNA. In contrast, the treatment of human immunodeficiency virus type 1-infected cells with SQLs reduced the amount of the late cDNA, suggesting for the first time that integrase targeting molecules may affect the accumulation of DNA during reverse transcription. The cellular target of SQLs was confirmed by the appearance of mutations in the integrase gene when viruses were grown in the presence of increasing concentrations of SQLs. Finally, these mutations led to SQL-resistant viruses when introduced into the wild-type sequence. In contrast, SQLs were fully active against reverse transcriptase inhibitor- and diketo acid-resistant viruses, positioning SQLs as a second group of anti-integrase compounds.

Linker-modified quinoline derivatives targeting HIV-1 integrase: synthesis and biological activity.

A novel series of HIV-1 integrase inhibitors was synthesized and tested in both in vitro and ex vivo assays. These inhibitors are featured by the presence of a quinoline subunit and an ancillary aromatic ring linked by functionalized spacers such as amide, hydrazide, urea and 1-hydroxyprop-1-en-3-one moiety. Amide derivatives are the most promising ones and could serve as leads for further developments.

Use of the Kohonen neural network for rapid screening of ex vivo anti-HIV activity of styrylquinolines.

Using the Kohonen neural network, the electrostatic potentials on the molecular surfaces of 14 styrylquinoline derivatives were drawn as comparative two-dimensional maps and compared with their known human immunodeficiency virus (HIV)-1 replication blocking potency in cells. A feature of the potential map was discovered to be related with the HIV-1 blocking activity and was used to unmask the activity of further five analogues, previously described but whose cytotoxicity precluded an estimation of their activity, and to predict the activity of 10 new compounds while the experimental data were unknown. The measurements performed later turned out to agree with the predictions.

Stereochemical Aspects in the Asymmetric Michael Addition of Chiral Imines to Substituted Electrophilic Alkenes.

The Michael-type addition of chiral imines, derived from racemic alpha-substituted cyclanones and optically active 1-phenylethylamine, to electrophilic alkenes, in neutral conditions, constitutes one of the most efficient methods for the stereocontrolled construction of quaternary carbon centers. In order to create an additional stereogenic center at the alpha- or beta-position to the quaternary one, the behavior of a variety of alpha- and beta-substituted alkenyl acceptors was examined. In general, these additions are highly regioselective, the alkylation taking place predominantly, if not exclusively, at the more substituted alpha-side of the imine function; however, in some cases (electrophilic alkenes 28 and 49), significant amounts (10-15%) of regioisomeric adducts were obtained. With the exception of methyl propiolate 52, a remarkable control of the absolute configuration of the adducts were always observed with these Michael acceptors. According to the general rule we have previously proposed, the alkylation process takes place preferentially on the less hindered pi-face of the more substituted secondary enamine, in tautomeric equilibrium with the starting imine. An excellent diastereocontrol was always obtained by using the present alpha- and beta-substituted alkenes. These stereochemical outcomes can be interpreted by invoking that the reaction proceeds through a compact approach of the reactants, the hydrogen atom at the nitrogen center of the enamine being transferred to the alpha-vinylic carbon atom of the acceptor, concertedly with the creation of the C-C bond. In this respect the "endo-approach" 58, in which the electron-withdrawing group of the acceptor faced to the nitrogen atom of the enamine (case of acceptors 10, methyl methacrylate, 24, 28, 43, 47, and 49) largely prevails over the "exo-approach" 59 (case of acceptor 38). This predominant "endo-preference" can be reasonably interpreted in terms of a cooperative effect between steric and stereoelectronic factors.