Mitotic cell death induction by targeting the mitotic spindle with tubulin-inhibitory indole derivative molecules.

Tubulin-targeting molecules are widely used cancer therapeutic agents. They inhibit microtubule-based structures, including the mitotic spindle, ultimately preventing cell division. The final fates of microtubule-inhibited cells are however often heterogeneous and difficult to predict. While recent work has provided insight into the cell response to inhibitors of microtubule dynamics (taxanes), the cell response to tubulin polymerization inhibitors remains less well characterized. Arylthioindoles (ATIs) are recently developed tubulin inhibitors. We previously identified ATI members that effectively inhibit tubulin polymerization in vitro and cancer cell growth in bulk cell viability assays. Here we characterise in depth the response of cancer cell lines to five selected ATIs. We find that all ATIs arrest mitotic progression, yet subsequently yield distinct cell fate profiles in time-lapse recording assays, indicating that molecules endowed with similar tubulin polymerization inhibitory activity in vitro can in fact display differential efficacy in living cells. Individual ATIs induce cytological phenotypes of increasing severity in terms of damage to the mitotic apparatus. That differentially triggers MCL-1 down-regulation and caspase-3 activation, and underlies the terminal fate of treated cells. Collectively, these results contribute to define the cell response to tubulin inhibitors and pinpoint potentially valuable molecules that can increase the molecular diversity of tubulin-targeting agents.

New Indole Tubulin Assembly Inhibitors Cause Stable Arrest of Mitotic Progression, Enhanced Stimulation of Natural Killer Cell Cytotoxic Activity, and Repression of Hedgehog-Dependent Cancer.

We designed 39 new 2-phenylindole derivatives as potential anticancer agents bearing the 3,4,5-trimethoxyphenyl moiety with a sulfur, ketone, or methylene bridging group at position 3 of the indole and with halogen or methoxy substituent(s) at positions 4-7. Compounds 33 and 44 strongly inhibited the growth of the P-glycoprotein-overexpressing multi-drug-resistant cell lines NCI/ADR-RES and Messa/Dx5. At 10 nM, 33 and 44 stimulated the cytotoxic activity of NK cells. At 20-50 nM, 33 and 44 arrested >80% of HeLa cells in the G2/M phase of the cell cycle, with stable arrest of mitotic progression. Cell cycle arrest was followed by cell death. Indoles 33, 44, and 81 showed strong inhibition of the SAG-induced Hedgehog signaling activation in NIH3T3 Shh-Light II cells with IC50 values of 19, 72, and 38 nM, respectively. Compounds of this class potently inhibited tubulin polymerization and cancer cell growth, including stimulation of natural killer cell cytotoxic activity and repression of Hedgehog-dependent cancer.

Evaluation of the Generalizability of the Number of Abnormal Scores and the Overall Test Battery Mean as Measures of Performance Validity to a Different Test Battery.

Davis, Axelrod, McHugh, Hanks, and Millis (2013) documented that in a battery of 25 tests, producing 15, 10, and 5 abnormal scores at 1, 1.5, and 2 standard deviations below the norm-referenced mean, respectively, and an overall test battery mean (OTBM) of T ≤ 38 accurately identifies performance invalidity. However, generalizability of these findings to other samples and test batteries remains unclear. This study evaluated the use of abnormal scores and the OTBM as performance validity measures in a different sample that was administered a 25-test battery that minimally overlapped with Davis et al.'s test battery. Archival analysis of 48 examinees with mild traumatic brain injury seen for medico-legal purposes was conducted. Producing 18 or more, 7 or more, and 5 or more abnormal scores at 1, 1.5, and 2 standard deviations below the norm-referenced mean, respectively, and an OTBM of T ≤ 40 most accurately classified examinees; however, using Davis et al.'s proposed cutoffs in the current sample maintained specificity at or near acceptable levels. Due to convergence across studies, producing ≥5 abnormal scores at 2 standard deviations below the norm-referenced mean is the most appropriate cutoff for clinical implementation; however, for batteries consisting of a different quantity of tests than 25, an OTBM of T ≤ 38 is more appropriate.

Rates of False-Positive Classification Resulting From the Analysis of Additional Embedded Performance Validity Measures.

Several studies have documented improvements in the classification accuracy of performance validity tests (PVTs) when they are combined to form aggregated models. Fewer studies have evaluated the impact of aggregating additional PVTs and changing the classification threshold within these models. A recent Monte Carlo simulation demonstrated that to maintain a false-positive rate (FPR) of ≤.10, only 1, 4, 8, 10, and 15 PVTs should be analyzed at classification thresholds of failing at least 1, at least 2, at least 3, at least 4, and at least 5 PVTs, respectively. The current study sought to evaluate these findings with embedded PVTs in a sample of real-life litigants and to highlight a potential danger in analytic flexibility with embedded PVTs. Results demonstrated that to maintain an FPR of ≤.10, only 3, 7, 10, 14, and 15 PVTs should be analyzed at classification thresholds of failing at least 1, at least 2, at least 3, at least 4, and at least 5 PVTs, respectively. Analyzing more than these numbers of PVTs resulted in a dramatic increase in the FPR. In addition, in the most extreme case, flexibility in analyzing and reporting embedded PVTs increased the FPR by 67%. Given these findings, a more objective approach to analyzing and reporting embedded PVTs should be introduced.

Performance Validity Classification Accuracy of Single-, Pairwise-, and Triple-Failure Models Using the Halstead-Reitan Neuropsychological Battery for Adults.

Embedded performance validity tests (PVTs) have been criticized for their poor specificity and sensitivity. Aggregated models of embedded PVTs have been proposed to improve their classification accuracy; however, limitations to aggregation-based improvement of PVTs have yet to be explored. The current study evaluated the classification accuracy of 3 types of models of embedded PVTs in the Halstead-Reitan Neuropsychological Battery for Adults (HRNB): a single-, a pairwise-, and a triple-failure model. In addition, this study evaluated the impact of aggregating between 1 and 6 embedded PVTs in each of these 3 types of models. Analyzing only the 2, 4, and 6 most discriminating embedded PVTs in the single-, pairwise-, and triple-failure models maximized classification accuracy, respectively. Comparisons across these models indicated that the single-failure model including only the two most discriminating embedded PVTs had the best classification accuracy; however, classification accuracy was only minimally improved in this model relative to analyzing just Reliable Digit Span. These results suggest that aggregation of embedded PVTs from the HRNB does not substantially improve their classification accuracy and that the benefits of aggregating PVTs may only emerge when the PVTs entered into the aggregated models have sufficient classification accuracy on their own.

New pyrrole derivatives with potent tubulin polymerization inhibiting activity as anticancer agents including hedgehog-dependent cancer.

We synthesized 3-aroyl-1-arylpyrrole (ARAP) derivatives as potential anticancer agents having different substituents at the pendant 1-phenyl ring. Both the 1-phenyl ring and 3-(3,4,5-trimethoxyphenyl)carbonyl moieties were mandatory to achieve potent inhibition of tubulin polymerization, binding of colchicine to tubulin, and cancer cell growth. ARAP 22 showed strong inhibition of the P-glycoprotein-overexpressing NCI-ADR-RES and Messa/Dx5MDR cell lines. Compounds 22 and 27 suppressed in vitro the Hedgehog signaling pathway, strongly reducing luciferase activity in SAG treated NIH3T3 Shh-Light II cells, and inhibited the growth of medulloblastoma D283 cells at nanomolar concentrations. ARAPs 22 and 27 represent a new potent class of tubulin polymerization and cancer cell growth inhibitors with the potential to inhibit the Hedgehog signaling pathway.

A comparison of the standard category test with a new computer version.

The Halstead Category Test is a popular measure of abstraction, concept formation, and logical analysis skills. Due to its large apparatus, however, ease of administration of the standard Category Test is limited. For this reason, a number of computer versions of the Category Test have been developed to facilitate its administration. The current study evaluated the equivalence of a new computer version to the standard Category Test in a sample of undergraduate students. Analyses revealed that the two versions did not differ significantly on subtest error scores, total error scores, or Neuropsychological Deficit Scale scores. Results of the current study support the equivalence of this new computer version to the standard version of the Category Test.

Can the Sensitivity and Specificity of the TOMM Be Increased with Differential Cutoff Scores?

Accurate determination of performance validity is paramount in any neuropsychological assessment. Numerous freestanding symptom validity tests, like the Test of Memory Malingering (TOMM), have been developed to assist in this process; however, research and clinical experiences have suggested that each may not function with the same classification accuracy. In an effort to increase the TOMM's ability to accurately classify performance validity, recent research has investigated the use of nonstandard cutoff scores. The purpose of this study was to potentially validate the use of two, nonstandard cutoff scores (<49 on Trial 2 or the Retention Trial or ≤39 on Trial 1) applied to the TOMM in a medicolegal sample of mild traumatic brain injury litigants. Both descriptive and inferential statistics found that the cutoff of <49 on Trial 2 or the Retention Trial was the most sensitive to performance validity as compared with both the standard TOMM criteria and the cutoff of ≤39. These findings support the use of nonstandard cutoffs to increase the TOMM's classification accuracy.

The degree of conation on neuropsychological tests does not account for performance invalidity among litigants.

Conation has been defined as the ability to focus and maintain intellectual energy over time. Prior research has shown that conation contributes to the magnitude of differences in test scores among brain-damaged and non-brain-damaged examinees. The purpose of the current investigation was to determine if conation might similarly account for differences in test scores among performance valid and performance invalid examinees. An archival analysis was therefore carried out on 52 examinees administered the Halstead-Reitan Neuropsychological Battery (HRNB) and several performance validity tests in a medico-legal context. Analyses revealed that conation had no impact on the magnitude of test score differences between groups and that performance invalid examinees scored worse than performance valid examinees on all but one test of the HRNB. These results support the idea that the identification of performance invalidity calls into question the reliability and the validity of all test score interpretations in an evaluation, even those with less conative load.

The fuld object-memory evaluation: development and validation of an alternate form.

The Fuld Object-Memory Evaluation (FOME) uses multisensory (tactile, visual, and verbal) encoding of objects for assessing memory, with particular clinical and research application in older adults. This preliminary study reports the first known psychometric data on the development of an alternate form of the FOME. Data were drawn from 102 independent-living older adults participating in a larger clinical trial. Seventy participants completed three versions of the shortened administration of the FOME, and comparability of forms was established by significant, moderate intraclass correlation coefficients for immediate and delayed recall scores. Reliable change indexes indicate the new alternate form performs well, with minimal practice or learning effects. Evidence of convergent and discriminant validity was documented using the Rey Auditory Verbal Learning Test, category fluency task, and North American Adult Reading Test. Normative data are provided stratified by age for participants completing at least one of three time points (n = 96). Results of this preliminary study provide evidence for the comparability and construct validity of a new alternate form of the FOME with prior forms. An additional well-validated form of the FOME has practical implications for serial testing often required in clinical practice and research design.

Performance of non-neurological older adults on the Wisconsin Card Sorting Test and the Stroop Color-Word Test: normal variability or cognitive impairment?

There is currently no standard criterion for determining abnormal test scores in neuropsychology; thus, a number of different criteria are commonly used. We investigated base rates of abnormal scores in healthy older adults using raw and T-scores from indices of the Wisconsin Card Sorting Test and Stroop Color-Word Test. Abnormal scores were examined cumulatively at seven cutoffs including >1.0, >1.5, >2.0, >2.5, and >3.0 standard deviations (SD) from the mean as well as those below the 10th and 5th percentiles. In addition, the number of abnormal scores at each of the seven cutoffs was also examined. Results showed when considering raw scores, ∼15% of individuals obtained scores>1.0 SD from the mean, around 10% were less than the 10th percentile, and 5% fell >1.5 SD or <5th percentile from the mean. Using T-scores, approximately 15%-20% and 5%-10% of scores were >1.0 and >1.5 SD from the mean, respectively. Roughly 15% and 5% fell at the <10th and <5th percentiles, respectively. Both raw and T-scores>2.0 SD from the mean were infrequent. Although the presence of a single abnormal score at 1.0 and 1.5 SD from the mean or at the 10th and 5th percentiles was not unusual, the presence of ≥2 abnormal scores using any criteria was uncommon. Consideration of base rate data regarding the percentage of healthy individuals scoring in the abnormal range should help avoid classifying normal variability as neuropsychological impairment.

The Albany Consistency Index for the Test of Memory Malingering.

The determination of examinee effort is an important component of a neuropsychological evaluation and relies heavily on the use of symptom validity tests (SVTs) such as the Test of Memory Malingering (TOMM) and the Word Memory Test (WMT). Diagnostic utility of SVTs varies. The sensitivity of traditional TOMM criteria to suboptimal effort is low. An index of response consistency across three trials of the TOMM was developed, denoted the Albany Consistency Index (ACI). This index identified a large proportion of examinees classified as optimal effort using traditional TOMM interpretive guidelines but suboptimal effort using the WMT profile analysis. In addition, previous research was extended, demonstrating a relationship between examinee performance on SVTs and neuropsychological tests. Effort classification using the ACI predicted the performance on the Global Memory Index from the Memory Assessment Scales. In conclusion, the ACI was a more sensitive indicator of suboptimal effort than traditional TOMM interpretive guidelines.

Are embedded validity indices equivalent to free-standing symptom validity tests?

Symptom validity assessment is an important part of neuropsychological evaluation. There are currently several free-standing symptom validity tests (SVTs), as well as a number of empirically derived embedded validity indices, that have been developed to assess that an examinee is putting forth an optimal level of effort during testing. The use of embedded validity indices is attractive since they do not increase overall testing time and may also be less vulnerable to coaching. In addition, there are some instances where embedded validity indices are the only tool available to the neuropsychological practitioner for assessing an examinee's level of effort. As with free-standing measures, the sensitivity and specificity of embedded validity indices to suboptimal effort varies. The present study evaluated the diagnostic validity of 17 embedded validity indices by comparing performance on these indices to performance on combinations of free-standing SVTs. Results from the current medico-legal sample revealed that of the embedded validity indices, Reliable Digit Span had the best classification accuracy; however, the findings do not support the use of this embedded validity index in the absence of free-standing SVTs.

Comparison of computerized versus booklet versions of the TOMM™.

This study examined whether there is a significant difference in performance on two different versions of the Test of Memory Malingering (TOMM; Tombaugh, 1996). Differences in performance were compared between the examiner-administered booklet version versus the self-administered computerized version. No statistically significant differences were found between performance on the two versions. These data indicate that the two versions of the TOMM produce equivalent performance, at least among college students. Further studies employing other populations are warranted.

Comparison of verbal memory impairment rates in mild cognitive impairment.

There are no accepted guidelines establishing the most sensitive neuropsychological methods to define memory impairment in mild cognitive impairment (MCI). We investigated whether similar impairment rates were observed between the Hopkins Verbal Learning Test-Revised (HVLT-R) and Logical Memory (LM) in 90 patients with amnestic or amnestic plus MCI. On HVLT-R delayed recall, 80% of participants performed in the MCI range compared to only 32.2% on LM II. The same pattern was seen for both amnestic and amnestic plus subtypes. Individuals impaired on HVLT-R delayed recall performed significantly worse on LM first recall and on delayed recall of LM Story A than those not impaired. MCI patients with executive dysfunction performed significantly worse than patients with no executive impairment on both LM I and HVLT-R Total Learning, but not for delayed recall of either measure. Future studies can address the longitudinal course of impairment on these measures.

The structure of individual differences in batteries of rapid acquisition tasks in mice.

Two experiments examined the structure of individual differences in mice by means of tasks that produced significant acquisition within 1 session. In Experiment 1, 5 cognitive tasks-detour, winshift, olfactory discrimination, fear conditioning, and operant acquisition-were used in conjunction with two control procedures: an open field and a light- dark test. In Experiment 2, some modifications were made to the tasks used in the 1st experiment, and 3 new tasks were used in conjunction with the same control procedures. The battery consisted of 5 learning tasks: detour, Hebb-Williams, radial maze, olfactory foraging, and fear conditioning. Results of both experiments indicate that when cognitive tasks and control procedures were included in principal-components analyses most of the variance attached principally to individual tasks rather than to a general component as is found typically in human cognitive batteries. When control procedures were eliminated, there was better evidence for the presence of a general cognitive factor, particularly in Experiment 2.