Tumor-Induced Cardiac Dysfunction: A Potential Role of ROS.

Cancer and heart diseases are the two leading causes of mortality and morbidity worldwide. Many cancer patients undergo heart-related complications resulting in high incidences of mortality. It is generally hypothesized that cardiac dysfunction in cancer patients occurs due to cardiotoxicity induced by therapeutic agents, used to treat cancers and/or cancer-induced cachexia. However, it is not known if localized tumors or unregulated cell growth systemically affect heart function before treatment, and/or prior to the onset of cachexia, hence, making the heart vulnerable to structural or functional abnormalities in later stages of the disease. We incorporated complementary mouse and Drosophila models to establish if tumor induction indeed causes cardiac defects even before intervention with chemotherapy or onset of cachexia. We focused on one of the key pathways involved in irregular cell growth, the Hippo-Yorkie (Yki), pathway. We used overexpression of the transcriptional co-activator of the Yki signaling pathway to induce cellular overgrowth, and show that Yki overexpression in the eye tissue of Drosophila results in compromised cardiac function. We rescue these cardiac phenotypes using antioxidant treatment, with which we conclude that the Yki induced tumorigenesis causes a systemic increase in ROS affecting cardiac function. Our results show that systemic cardiac dysfunction occurs due to abnormal cellular overgrowth or cancer elsewhere in the body; identification of specific cardiac defects associated with oncogenic pathways can facilitate the possible early diagnosis of cardiac dysfunction.

Metabolic shifts modulate lung injury caused by infection with H1N1 influenza A virus.

Influenza A virus (IAV) infection alters lung epithelial cell metabolism in vitro by promoting a glycolytic shift. We hypothesized that this shift benefits the virus rather than the host and that inhibition of glycolysis would improve infection outcomes. A/WSN/33 IAV-inoculated C57BL/6 mice were treated daily from 1 day post-inoculation (d.p.i.) with 2-deoxy-d-glucose (2-DG) to inhibit glycolysis and with the pyruvate dehydrogenase kinase (PDK) inhibitor dichloroacetate (DCA) to promote flux through the TCA cycle. To block OXPHOS, mice were treated every other day from 1 d.p.i. with the Complex I inhibitor rotenone (ROT). 2-DG significantly decreased nocturnal activity, reduced respiratory exchange ratios, worsened hypoxemia, exacerbated lung dysfunction, and increased humoral inflammation at 6 d.p.i. DCA and ROT treatment normalized oxygenation and airway resistance and attenuated IAV-induced pulmonary edema, histopathology, and nitrotyrosine formation. None of the treatments altered viral replication. These data suggest that a shift to glycolysis is host-protective in influenza.

BKCa (Slo) Channel Regulates Mitochondrial Function and Lifespan in Drosophila melanogaster.

BKCa channels, originally discovered in Drosophila melanogaster as slowpoke (slo), are recognized for their roles in cellular and organ physiology. Pharmacological approaches implicated BKCa channels in cellular and organ protection possibly for their ability to modulate mitochondrial function. However, the direct role of BKCa channels in regulating mitochondrial structure and function is not deciphered. Here, we demonstrate that BKCa channels are present in fly mitochondria, and slo mutants show structural and functional defects in mitochondria. slo mutants display an increase in reactive oxygen species and the modulation of ROS affected their survival. We also found that the absence of BKCa channels reduced the lifespan of Drosophila, and overexpression of human BKCa channels in flies extends life span in males. Our study establishes the presence of BKCa channels in mitochondria of Drosophila and ascertains its novel physiological role in regulating mitochondrial structural and functional integrity, and lifespan.

Effect of Three Behavior Guidance Techniques on Anxiety Indicators of Children Undergoing Diagnosis and Preventive Dental Care.

Objective(s): To assess the effect of three behavior guidance techniques on anxiety indicators of children undergoing diagnosis and preventive dental care. Study Design: Sixty-three subjects (7-9 years) were divided into three groups as per the behavior guidance technique namely tell-show-do, live and filmed modeling (using Tablet Computer) to receive diagnostic (Oral examination & radiographic assessment using intraoral periapical radiographs) and preventive dental care (Oral prophylaxis and topical fluoride application). Anxiety indicators-Facial Image Scale (FIS) scores and heart rate were recorded before, during and after diagnosis/preventive treatment. Three-way repeated measures ANOVA with post-hoc analysis was performed at significance of p-value < 0.05. Results: There was a statistically significant difference in the anxiety indicators of children under the influence of different behavior guidance approaches undergoing diagnosis/preventive treatments except for mean heart rate of children while oral examination. Multiple comparison results reveal that the mean FIS scores and heart rate of children with modeling techniques were significantly better as compared to tell-show-do technique with no significant difference between the two modeling techniques. Conclusion: This study suggests that the modeling techniques (filmed and live) seem to be an efficient behavioral guidance approach for children aged 7-9 years undergoing routine diagnosis and preventive dental care as compared to tell-show-do technique.

Drosophila Voltage-Gated Calcium Channel α1-Subunits Regulate Cardiac Function in the Aging Heart.

Ion channels maintain numerous physiological functions and regulate signaling pathways. They are the key targets for cellular reactive oxygen species (ROS), acting as signaling switches between ROS and ionic homeostasis. We have carried out a paraquat (PQ) screen in Drosophila to identify ion channels regulating the ROS handling and survival in Drosophila melanogaster. Our screen has revealed that α1-subunits (D-type, T-type, and cacophony) of voltage-gated calcium channels (VGCCs) handle PQ-mediated ROS stress differentially in a gender-based manner. Since ROS are also involved in determining the lifespan, we discovered that the absence of T-type and cacophony decreased the lifespan while the absence of D-type maintained a similar lifespan to that of the wild-type strain. VGCCs are also responsible for electrical signaling in cardiac cells. The cardiac function of each mutant was evaluated through optical coherence tomography (OCT), which revealed that α1-subunits of VGCCs are essential in maintaining cardiac rhythmicity and cardiac function in an age-dependent manner. Our results establish specific roles of α1-subunits of VGCCs in the functioning of the aging heart.

Expression and Activation of BKCa Channels in Mice Protects Against Ischemia-Reperfusion Injury of Isolated Hearts by Modulating Mitochondrial Function.

Aims: Activation and expression of large conductance calcium and voltage-activated potassium channel (BKCa) by pharmacological agents have been implicated in cardioprotection from ischemia-reperfusion (IR) injury possibly by regulating mitochondrial function. Given the non-specific effects of pharmacological agents, it is not clear whether activation of BKCa is critical to cardioprotection. In this study, we aimed to decipher the mechanistic role of BKCa in cardioprotection from IR injury by genetically activating BKCa channels. Methods and Results: Hearts from adult (3 months old) wild-type mice (C57/BL6) and mice expressing genetically activated BKCa (Tg-BKCa R207Q, referred as Tg-BKCa) along with wild-type BKCa were subjected to 20 min of ischemia and 30 min of reperfusion with or without ischemic preconditioning (IPC, 2 times for 2.5 min interval each). Left ventricular developed pressure (LVDP) was recorded using Millar's Mikrotip® catheter connected to ADInstrument data acquisition system. Myocardial infarction was quantified by 2,3,5-triphenyl tetrazolium chloride (TTC) staining. Our results demonstrated that Tg-BKCa mice are protected from IR injury, and BKCa also contributes to IPC-mediated cardioprotection. Cardiac function parameters were also measured by echocardiography and no differences were observed in left ventricular ejection fraction, fractional shortening and aortic velocities. Amplex Red® was used to assess reactive oxygen species (ROS) production in isolated mitochondria by spectrofluorometry. We found that genetic activation of BKCa reduces ROS after IR stress. Adult cardiomyocytes and mitochondria from Tg-BKCa mice were isolated and labeled with Anti-BKCa antibodies. Images acquired via confocal microscopy revealed localization of cardiac BKCa in the mitochondria. Conclusions: Activation of BKCa is essential for recovery of cardiac function after IR injury and is likely a factor in IPC mediated cardioprotection. Genetic activation of BKCa reduces ROS produced by complex I and complex II/III in Tg-BKCa mice after IR, and IPC further decreases it. These results implicate BKCa-mediated cardioprotection, in part, by reducing mitochondrial ROS production. Localization of Tg-BKCa in adult cardiomyocytes of transgenic mice was similar to BKCa in wild-type mice.

Comparative evaluation and correlation of salivary total antioxidant capacity and salivary pH in caries-free and severe early childhood caries children.

BACKGROUND: Dental caries is a major problem in preschool children. The contribution of saliva in providing defense during caries process is of primary importance. pH buffer capacity through bicarbonate, phosphate and protein buffer systems have universal acceptance as a caries defense mechanism. Antioxidant capacity of saliva can constitute a first line of defense against chronic degenerative diseases including dental caries. Till date, no study is presented with salivary antioxidant capacity of younger children affected with severe early childhood caries with its salivary pH correlation. Hence, this study was carried out to compare, evaluate and correlate the salivary total antioxidant capacity (TAC) and salivary pH of children with caries-free and severe early childhood caries. MATERIALS AND METHODS: Fifty children from ages 3 to 5 years divided into two study groups had undergone screening. Group I (n = 25) with severe early childhood caries (S-ECC) and group II (n = 25) who were caries free. Unstimulated whole saliva of subjects were in the collection during the study by draining method. Salivary pH determination of saliva samples was done using pH indicator paper strips. The TAC was done using an antioxidant assay with the help of a spectrophotometer at wavelength 532 nm. The means of salivary pH and TAC were subjected to analysis using unpaired student 't' test and correlation was determined using Pearsons correlation coefficient analysis. RESULTS: Mean salivary pH was higher in group II (7.46 ± 0.37). Mean TAC was greater in group I (1.82 ± 0.19). A statistically significant negative correlation as seen between TAC and salivary pH in S-ECC patients. CONCLUSION: The study concludes that salivary TAC increases in patients with S-ECC are by that showing a high indirect relationship with salivary pH.