Exploring treatment with Ribociclib alone or in sequence/combination with Everolimus in ER+HER2−Rb wild-type and knock-down in breast cancer cell lines

Background Breast cancer (BC) is the second most common type of cancer worldwide. Among targeted therapies for Hormone Receptor-positive (HR+) and Human Epidermal growth factor Receptor 2-negative (HER2−) BC, the Cyclin-Dependent Kinases (CDK4/6) are targeted by inhibitors such as Ribociclib (Rib); however, resistance to CDK4/6 inhibitors frequently develops. The aim of this work is to assess in vitro activity of Rib and Everolimus (Eve) in HR+HER2− MCF-7 and HR−HER2−BT-549 BC cell lines. Methods HR+HER2− MCF-7 and HR−HER2− BT-549 BC cell lines were treated with increasing concentration of Rib and Eve (up to 80 μg/mL) for 48–72 h. Subsequently, HR+HER2− MCF-7 cells were silenced for Retinoblastoma (Rb) gene, and thus, the effect of Rib in sequential or concurrent schedule with Eve for the treatment of both Rb wild type or Rb knock-down MCF-7 in vitro was evaluated. Cell viability of HR+HER2− MCF-7cells treated with sequential and concurrent dosing schedule was analyzed by MTT assay. Moreover, cell cycle phases, cell death and senescence were evaluated by cytofluorimetric analysis after treatment with Rib or Eve alone or in combination. Results The sequential treatment didn’t produce a significant increase of cytotoxicity, compared to Rib alone. Instead, the cotreatment synergized to increase the cytotoxicity compared to Rib alone. The cotreatment reduced the percentage of cells in S and G2/M phases and induced apoptosis. Rib triggered senescence and Eve completely reversed this effect in Rb wild type BC cells. Rib also showed Rb-independent effects as shown by results in Rb knock-down MCF-7. Conclusion Overall, the Rib/Eve concurrent therapy augmented the in vitro cytotoxic effect, compared to Rib/Eve sequential therapy or single treatments.

Extinguishing cocaine-associated discriminative stimuli attenuates cocaine vs food choice in male rhesus monkeys

ABSTRACTBackgroundIn drug addiction, relapse can be triggered by cues that function as discriminative stimuli to signal contingencies of drug availability and promote drug-taking behavior. Extinction procedures can weaken the association between drug-associated cues and drug use and may reduce the probability of relapse. This study evaluated effects of a regimen of extinction training on cocaine self-administration maintained in rhesus monkeys under a cocaine-vs.-food choice procedure that has been used previously to evaluate effectiveness of other candidate treatments for cocaine abuse.MethodsBehavior was initially maintained under a concurrent schedule of food delivery (1-g food pellets; fixed-ratio 100 schedule) and cocaine injections (0-0.1 mg/kg/injection; fixed-ratio 10 schedule) during daily 2-h choice sessions in male rhesus monkeys (n=4). Subsequently, choice sessions were supplemented by daily 20-h extinction sessions for 14 consecutive days. During extinction sessions, cocaine-associated discriminative stimuli were presented, but responding did not produce cocaine injections. Cocaine continued to be available during choice sessions.ResultsPrior to extinction, cocaine maintained a dose-dependent increase in cocaine vs. food choice. Responding during extinction sessions declined to low levels by the fifth day. Exposure to extinction sessions produced a more gradual but significant decline in cocaine choice and a complementary increase in food choice during choice sessions.ConclusionsThese preclinical results support the effectiveness of extinguishing cocaine-associated discriminative stimuli as a non-pharmacological treatment strategy for reducing cocaine choice. Moreover, these results also support the construct validity of preclinical drug vs. food choice procedures as a tool for candidate treatment evaluation for cocaine addiction.

Choice Under Conditions of Uncertainty

All behavior varies, and behavior under a wide range of circumstances displays high levels of variability. This is especially true under many concurrent schedules of reinforcement, despite those schedules not being designed to elicit unpredictable behavior. A generalized matching analysis was performed to measure the effects of reinforcement on 5-item choice under two conditions: Probabilistic concurrent schedules and threshold-based operant variability schedules. Behavior was analyzed in terms of conditional probabilities, incorporating trial-by-trial response dynamics into the model. Performing this analysis meant overcoming a major difficulty: Obtained reinforcement is not a valid independent predictor of behavior the two are causally interlinked. The method of instrumental variable estimation is utilized to overcome the “endogeneity” of reinforcement, which permits unbiased estimation of the causal influence of reinforcement on responding. The analysis revealed a simple relationship between choices made and the distances traveled to make them. Subjects were more willing to travel through the chamber under the Concurrent schedule than under the Variability schedule. As a result, with respect to predicting a subject’s next response, Concurrent schedules elicited higher levels of behavioral variability than did Variability schedules. However, longer-term behavior under the Variability schedules better resembled a steady-state random process.

Extracting Energy From the Hydrodynamic Instability of a Yawing Flat Plate

The extraction of energy from currents is still an issue. Both design point and off-design behavior should be addressed conveniently. In the present study, a new concept based on the flow-induced instability of an elastic structure is introduced by which the energy can be extracted from the water current. The energy extractor device is named “Fernandes-Armandei”, which consists of a simple flat plate attached to a torsion spring and located vertically in the water current. The flat plate has only 1 DOF that is yawing about its axis, which is in its mid chord length. A concurrent-schedule research (Armandei and Fernandes, 2012) demonstrates that one such motion becomes dynamically unstable, as the velocity exceeds a special threshold. The motivation of doing this research was the robustness of the oscillations created due to the flow-induced instability. Two different cases (a) and (b) are studied, case (a) with larger natural frequency and case (b) with larger mass moment and added moment of inertia. A damper is also applied in the device as a transmission system which converts oscillation to rotation. The rotary motion is utilized to lift a weight up to a prescribed height, to assess the energy extraction behavior of each case. The results show that case (b) can lift heavier weights than case (a). However, the maximum efficiency of case (a) (9.18%) is about three times more than the maximum efficiency of case (b) (3.26%).