Covalent Degrader of the Oncogenic Transcription Factor ß-Catenin.

ß-catenin (CTNNB1) is an oncogenic transcription factor that is important in cell-cell adhesion and transcription of cell proliferation and survival genes that drive the pathogenesis of many different types of cancers. However, direct pharmacological targeting of CTNNB1 has remained challenging. Here, we have performed a screen with a library of cysteine-reactive covalent ligands to identify the monovalent degrader EN83 that depletes CTNNB1 in a ubiquitin-proteasome-dependent manner. We show that EN83 directly and covalently targets CTNNB1 three cysteines C466, C520, and C619, leading to destabilization and degradation of CTNNB1. Through structural optimization, we generate a highly potent and relatively selective destabilizing degrader that acts through the targeting of only C619 on CTNNB1. Our results show that chemoproteomic approaches can be used to covalently target and degrade challenging transcription factors like CTNNB1 through destabilization-mediated degradation.

Ophiobolin A Covalently Targets Mitochondrial Complex IV Leading to Metabolic Collapse in Cancer Cells.

Ophiobolin A (OPA) is a sesterterpenoid fungal natural product with broad anticancer activity. While OPA possesses multiple electrophilic moieties that can covalently react with nucleophilic amino acids on proteins, the proteome-wide targets and mechanism of OPA remain poorly understood in many contexts. In this study, we used covalent chemoproteomic platforms to map the proteome-wide reactivity of the OPA in a highly sensitive lung cancer cell line. Among several proteins that OPA engaged, we focused on two targets: lysine-72 of cytochrome c oxidase subunit 5A (COX5A) and cysteine-53 of mitochondrial hypoxia induced gene 1 domain family member 2A (HIGD2A). These two subunit proteins are part of complex IV (cytochrome C oxidase) within the electron transport chain and contributed significantly to the antiproliferative activity of OPA. OPA activated mitochondrial respiration in a COX5A- and HIGD2A-dependent manner, leading to an initial spike in mitochondrial ATP and heightened mitochondrial oxidative stress. OPA compromised mitochondrial membrane potential, ultimately leading to ATP depletion. We have used chemoproteomic strategies to discover a unique anticancer mechanism of OPA through activation of complex IV leading to compromised mitochondrial energetics and rapid cell death.

Covalent Degrader of the Oncogenic Transcription Factor ß-Catenin.

ß-catenin (CTNNB1) is an oncogenic transcription factor that is important in cell-cell adhesion and transcription of cell proliferation and survival genes that drives the pathogenesis of many different types of cancers. However, direct pharmacological targeting of CTNNB1 has remained challenging deeming this transcription factor as "undruggable." Here, we have performed a screen with a library of cysteine-reactive covalent ligands to identify a monovalent degrader EN83 that depletes CTNNB1 in a ubiquitin-proteasome-dependent manner. We show that EN83 directly and covalently targets CTNNB1 through targeting four distinct cysteines within the armadillo repeat domain-C439, C466, C520, and C619-leading to a destabilization of CTNNB1. Using covalent chemoproteomic approaches, we show that EN83 directly engages CTNNB1 in cells with a moderate degree of selectivity. We further demonstrate that direct covalent targeting of three of these four cysteines--C466, C520, and C619--in cells contributes to CTNNB1 degradation in cells. We also demonstrate that EN83 can be further optimized to yield more potent CTNNB1 binders and degraders. Our results show that chemoproteomic approaches can be used to covalently target and degrade challenging transcription factors like CTNNB1 through a destabilization-mediated degradation.

Ophiobolin A Covalently Targets Complex IV Leading to Mitochondrial Metabolic Collapse in Cancer Cells.

Ophiobolin A (OPA) is a sesterterpenoid fungal natural product with broad anti-cancer activity. While OPA possesses multiple electrophilic moieties that can covalently react with nucleophilic amino acids on proteins, the proteome-wide targets and mechanism of OPA remain poorly understood in many contexts. In this study, we used covalent chemoproteomic platforms to map the proteome-wide reactivity of OPA in a highly sensitive lung cancer cell line. Among several proteins that OPA engaged, we focused on two targets-cysteine C53 of HIG2DA and lysine K72 of COX5A-that are part of complex IV of the electron transport chain and contributed significantly to the anti-proliferative activity. OPA activated mitochondrial respiration in a HIG2DA and COX5A-dependent manner, led to an initial spike in mitochondrial ATP, but then compromised mitochondrial membrane potential leading to ATP depletion. We have used chemoproteomic strategies to discover a unique anti-cancer mechanism of OPA through activation of complex IV leading to compromised mitochondrial energetics and rapid cell death.

Cardio-protective effect of dapagliflozin against doxorubicin induced cardiomyopathy in rats.

OBJECTIVE: Cancer is the second most common non-communicable disease group in the world and its frequency is increasing. In parallel, side effects of drugs used in cancer treatment are frequently encountered. Doxorubicin (DOX) is one of the most effective multi-purpose anticancer drugs. However, its use is significantly limited due to the risk of cardiotoxicity. Sodium-glucose cotransporter-2 inhibitors are a group of antidiabetic drugs that have been shown to reduce cardiovascular events. Our aim is to examine the preventive effect of dapagliflozin on DOX-induced cardiac damage. SUBJECTS AND METHODS: We used 30 albino rats. 20 of 30 rats were administered doxorubicin for cardiomyopathy model. The rats in the DOX arm were divided into two groups: those given penicillin and placebo. After the rats were terminated, tissues were prepared for histopathological and immunohistochemical examination. TNF-α, pro-BNP, troponin T and plasma FGF-21 levels were also measured in plasma. RESULTS: The mean concentrations of cTnT and pro-BNP in the plasma of the DOX treated rats demonstrated a significantly higher value compared to the control group. Treatment with dapagliflozin caused a significant reduction in plasma cTnT, pro-BNP and TNF-α levels concentrations compared to the DOX control group (p < 0.001). The group of rats treated with dapagliflozin was effective in significantly decreasing the FGF-21 concentration and the percentage of fibronectin immunoexpression compared to the DOX control group (p  < 0.0001). CONCLUSIONS: This study revealed, for the first time, that dapagliflozin can improve DOX-induced cardiac dysfunction and pathological changes in non-diabetic rats. This result has shown that dapaglifozin, may be promising in terms of preventing cardiac damage that may develop in cancer treatment.

Dental injuries among children and adolescents aged 1-15 years attending to public hospital in Temuco, Chile.

A cross-sectional study was carried out in children and adolescents of both sexes, aged 1-15 years that sought dental emergency attention to the Regional Hospital between 2004 and 2007 in Temuco, Chile. The purpose of this study was to identify the aetiology, types of traumatic dental injuries in primary and permanent dentitions, sex and age distributions, accident location; and time elapsed before emergency treatment in children and adolescents. The sample consisted of 359 patients with 145 primary teeth and 525 permanent teeth affected by dental trauma. The results showed a 2:1 male:female ratio distribution (242/117) with a mean age of 8.4 years. The 7- to 12-year-old group had the highest frequency of dental injuries (66.6%). Unspecific accidental falls were the main cause of injury to primary and permanent dentition (51.8%), followed by striking teeth against objects (15.6%) and bike accidents (13.9%). In primary dentition the most common diagnosis were subluxation (38.6%) and avulsion (16.6%), whereas in permanent dentition was uncomplicated crown fracture (32.9%). A high proportion of the patients received their first emergency attention 24 h after the accident (32.6%). This study revealed a high frequency (37.9%) in 1-15 aged population that sought emergency attention by dental trauma in the period of time study. A large proportion of children with dental trauma received delayed first emergency care, even 24 h after the accident. Considering the high frequency of traumatic dental injuries in 1-15 aged population and the high percentage of delayed emergency attention is necessary to develop effective educational campaigns in regard to causes, prevention and emergency management of traumatic dental injuries, especially in deprived areas. In conclusion, traumatic dental injury may be considered as a serious dental public health problem especially in children of deprived areas.

Determination of bioavailable soluble arsenic and phosphates in mine tailings by spectrophotometric Sequential Injection Analysis.

By using a simple Sequential Injection Analysis (SIA) manifold and in base to the kinetic reaction of the molybdenum with As(V) and P(V) was possible to determine As(III), As(V) and P(V) in simple, binary and ternary samples. The activation energies for the reaction between molybdenum and As(V) and P(V) were of 70.90 kJ mol(-1) and of 19.02 kJ mol(-1), respectively, therefore it was possible to determine both analytes in mixtures by using different reaction temperature. When the analyses were carried out at room temperature, only the P(V) supplied analytical signal; with increased temperature, the kinetics of reaction for As(V) also increased, and a signal was obtained, being 55 degrees C the optimum temperature. In order to determine As(III), it was oxidized into As(V) with KIO(3,) and the reaction was carried out in the same way as for As(V). To resolve mixtures, an equations system from six calibration curves with different sequences of SIA at different temperature was performed. The lineal ranges were between 0.5 microg mL(-1) and 10 microg mL(-1) with a repeatability and reproducibility between 0.7% and 5.2% and detection limits between 0.36 microg mL(-1) and 0.58 microg mL(-1). In binary mixtures of P(V)/As(V) the recoveries were close to 100% for both analytes at ratios lesser than 10:1. For As(V)/As(III) ratios between 1:1 and 5:1 the recoveries were ranged between 85% and 95%. The method was applied in mine tailings and in arsenopyrite. The results showed that the soluble arsenic was found oxidized as As(V). These results were compared with those obtained by atomic absorption spectrometry and both proved to be very close.

Signals, resistance to change, and conditioned reinforcement in a multiple schedule.

The effect of signals on resistance to change was evaluated using pigeons responding on a three-component multiple schedule. Each component contained a variable-interval initial link followed by a fixed-time terminal link. One component was an unsignaled-delay schedule, and two were equivalent signaled-delay schedules. After baseline training, resistance to change was assessed through (a) extinction and (b) adding free food to the intercomponent interval. During these tests, the signal stimulus from one of the signaled-delay components (SIG-T) was replaced with the initial-link stimulus from that component, converting it to an unsignaled-delay schedule. That signal stimulus was added to the delay period of the unsignaled-delay component (UNS), converting it to a signaled-delay schedule. The remaining signaled component remained unchanged (SIG-C). Resistance-to-change tests showed removing the signal had a minimal effect on resistance to change in the SIG-T component compared to the unchanged SIG-C component except for one block during free-food testing. Adding the signal to the UNS component significantly increased response rates suggesting that component had low response strength. Interestingly, the direction of the effect was in the opposite direction from what is typically observed. Results are consistent with the conclusion that the signal functioned as a conditioned reinforcer and inconsistent with a generalization-decrement explanation.

Effect of unsignaled delays between stimuli in a chain schedule on responding and resistance to change.

Behavioral momentum theory is an evolving theoretical account of the strength of behavior. One challenge for the theory is determining the role of signal stimuli in determining response strength. This study evaluated the effect of an unsignaled delay between the initial link and terminal link of a two-link chain schedule on resistance to change using a multiple schedule of reinforcement. Pigeons were presented two different signaled delay to reinforcement schedules. Both schedules employed a two-link chain schedule with a variable interval 120-s initial link followed by a 5-s fixed time terminal link schedule. One of the schedules included a 5-s unsignaled delay between the initial link and the terminal link. Resistance to change was assessed with two separate disruption procedures: extinction and adding a variable time 20-s schedule of reinforcement to the inter-component interval. Baseline responding was lower in the schedule with the unsignaled delay but resistance to change for the initial link was unaffected by the unsignaled delay. The results suggest that not all unsignaled delays are equal in their effect on resistance to change.

Loss of consciousness from acute quetiapine overdosage.

BACKGROUND: Quetiapine (Seroquel) is a new atypical antipsychotic agent developed for the treatment of schizophrenia. This dibenzothiazepine derivative possesses high affinity for 5-HT2 receptors with lower affinity for D1 and D2 dopamine receptors. In comparison to other antipsychotic agents, quetiapine has less antimuscarinic and alpha1 antagonist receptor activity. Overdose reports outside of clinical trials are limited. We report an intentional overdose of quetiapine by a schizophrenic. CASE REPORT: A 26-year-old female presented to the emergency department following an alleged ingestion of greater than 10,000 mg of quetiapine. At 1 1/2 hours postingestion, the patient was awake, ambulatory, and responded to verbal stimuli. At 2 1/2 hours postingestion, the patient experienced a decreased level of consciousness and responded only to deep pain. Physical findings included sinus tachycardia, pupils 3-4 mm and sluggish, and BP 135/70. Within 16 hours, the patient became awake and alert and was subsequently extubated. Serum electrolytes and blood count were unremarkable. The electrocardiogram at 18 hours postingestion showed a sinus tachycardia, which lasted for approximately 40 hours postingestion. A follow-up electrocardiogram at 42 hours postingestion was normal. CONCLUSION: This ingestion resulted in the loss of consciousness with need for airway protection and persistent tachycardia. Major overdoses of quetiapine warrant close observation in an intensive care setting.

The template-VLC provisional restoration system.

The removal of tooth structure during preparation results in varying degrees of pulpal hyperemia. The ability of the pulpal tissue to respond either by recovery or degeneration depends in part upon the adequacy and fit of the provisional restoration. The response of the gingival tissue also depends on a large degree on the success of the temporary coverage. Provisional restorations are commonly given less attention and importance thereby biologic, mechanical, and esthetic considerations are not adequately met. Since a provisional restoration must be made or improvised during the same appointment in which the abutment teeth are prepared, costly chairside time most often leads to an unacceptable restoration. Failures such as color instability, color incompatibility, inappropriate anatomic contours, fractures, occlusal disharmony, changes in tooth position, gingival inflammation, and unhealthy periodontal conditions are usually encountered. A technique of fabricating an exacting provisional restoration with compliance to optimum quality is presented.