Epigenetic effects of benzo(a)pyrene in Fundulus heteroclitus and Danio rerio

DNA methylation is one of the epigenetic mechanisms that controls gene expression and is vulnerable to early life environmental toxicant exposures. Our goal was to use two fish models, Fundulus heteroclitus and Danio rerio (zebrafish), to study the benzo(a)pyrene (BaP) effects on DNA methylation status and whether the alterations could contribute to BaP-mediated reproductive and developmental toxicities. Initially, we used Fundulus to study BaP effects on glycine N-methyltransferase (GNMT) expression throughout development. Fundulus embryos were exposed to waterborne BaP at nominally 10 or 100 μg/L and both GNMT mRNA expression and enzyme activity were measured. Quantitative PCR and whole mount in situ hybridization shosignificant GNMT mRNA induction by BaP, whereas enzyme activity was significantly inhibited in the Fundulus embryos. In zebrafish embryos, however, neither significant changes in GNMT gene expression nor enzyme activity were detected after BaP (1, 10 or 100 μg/L) exposure. Similarly, BaP exposure did not change DNA methyltransferase 1 (DNMT1) mRNA expression at 48, 60 or 96 hours post fertilization (hpf) or nuclear DNMT1 enzyme activity at 96 hpf. Direct waterborne BaP treatment at 100 μg/L from 2.5 to 96 hpf to zebrafish embryos did significantly decrease global DNA methylation by 55% and gene-specifically reduced promoter CpG methylation in vasa by 17%. As a result, vasa mRNA expression was significantly increased by 33% after exposure. However, BaP at 100 μg/L did not change CpG island methylation or gene expression in Ras-association domain family member 1 (RASSF1), telomerase reverse transcriptase (TERT), c-Jun and c-Myca at 96 hpf. Teratogenic effects (e.g. delayed hatching, pericardial edema, head and tail deformity) were observed in the BaP-treated embryos. Parental zebrafish were also exposed to 23±2.3 or 42±1.9 μg/L BaP to measure the adverse impact on fish reproduction. Although BaP was detected in the exposed fish ovaries, egg production was not affected. However, when the offspring were continuously exposed, they demonstrated DNA hypomethylation, high mortality and various deformities (e.g. pericardial edema, tube heart, head and tail deformity). In conclusion, BaP can cause global and gene specific DNA methylation changes in zebrafish embryos, which may play a role in BaP-induced reproductive and developmental toxicities

Regulation of Obesity and Metabolic Complications by Gamma and Delta Tocotrienols

Tocotrienols (T3s) are a subclass of unsaturated vitamin E that have been extensively studied for their anti-proliferative, anti-oxidative and anti-inflammatory properties in numerous cancer studies. Recently, T3s have received increasing attention due to their previously unrecognized property to attenuate obesity and its associated metabolic complications. In this review, we comprehensively evaluated the recent published scientific literature about the influence of T3s on obesity, with a particular emphasis on the signaling pathways involved. T3s have been demonstrated in animal models or human subjects to reduce fat mass, body weight, plasma concentrations of free fatty acid, triglycerides and cholesterol, as well as to improve glucose and insulin tolerance. Their mechanisms of action in adipose tissue mainly include (1) modulation of fat cell adipogenesis and differentiation; (2) modulation of energy sensing; (3) induction of apoptosis in preadipocytes and (4) modulation of inflammation. Studies have also been conducted to investigate the effects of T3s on other targets, e.g., the immune system, liver, muscle, pancreas and bone. Since δT3 and γT3 are regarded as the most active isomers among T3s, their clinical relevance to reduce obesity should be investigated in human trials

Embryonic Caffeine Exposure Acts via A1 Adenosine Receptors to Alter Adult Cardiac Function and DNA Methylation in Mice

Evidence indicates that disruption of normal prenatal development influences an individual's risk of developing obesity and cardiovascular disease as an adult. Thus, understanding how in utero exposure to chemical agents leads to increased susceptibility to adult diseases is a critical health related issue. Our aim was to determine whether adenosine A1 receptors (A1ARs) mediate the long-term effects of in utero caffeine exposure on cardiac function and whether these long-term effects are the result of changes in DNA methylation patterns in adult hearts. Pregnant A1AR knockout mice were treated with caffeine (20 mg/kg) or vehicle (0.09% NaCl) i.p. at embryonic day 8.5. This caffeine treatment results in serum levels equivalent to the consumption of 2–4 cups of coffee in humans. After dams gave birth, offspring were examined at 8–10 weeks of age. A1AR+/+ offspring treated in utero with caffeine were 10% heavier than vehicle controls. Using echocardiography, we observed altered cardiac function and morphology in adult mice exposed to caffeine in utero. Caffeine treatment decreased cardiac output by 11% and increased left ventricular wall thickness by 29% during diastole. Using DNA methylation arrays, we identified altered DNA methylation patterns in A1AR+/+ caffeine treated hearts, including 7719 differentially methylated regions (DMRs) within the genome and an overall decrease in DNA methylation of 26%. Analysis of genes associated with DMRs revealed that many are associated with cardiac hypertrophy. These data demonstrate that A1ARs mediate in utero caffeine effects on cardiac function and growth and that caffeine exposure leads to changes in DNA methylation

Regulation of Obesity and Metabolic Complications by Gamma and Delta Tocotrienols

Tocotrienols (T3s) are a subclass of unsaturated vitamin E that have been extensively studied for their anti-proliferative, anti-oxidative and anti-inflammatory properties in numerous cancer studies. Recently, T3s have received increasing attention due to their previously unrecognized property to attenuate obesity and its associated metabolic complications. In this review, we comprehensively evaluated the recent published scientific literature about the influence of T3s on obesity, with a particular emphasis on the signaling pathways involved. T3s have been demonstrated in animal models or human subjects to reduce fat mass, body weight, plasma concentrations of free fatty acid, triglycerides and cholesterol, as well as to improve glucose and insulin tolerance. Their mechanisms of action in adipose tissue mainly include (1) modulation of fat cell adipogenesis and differentiation; (2) modulation of energy sensing; (3) induction of apoptosis in preadipocytes and (4) modulation of inflammation. Studies have also been conducted to investigate the effects of T3s on other targets, e.g., the immune system, liver, muscle, pancreas and bone. Since δT3 and γT3 are regarded as the most active isomers among T3s, their clinical relevance to reduce obesity should be investigated in human trials

Regulation of Obesity and Metabolic Complications by Gamma and Delta Tocotrienols

Tocotrienols (T3s) are a subclass of unsaturated vitamin E that have been extensively studied for their anti-proliferative, anti-oxidative and anti-inflammatory properties in numerous cancer studies. Recently, T3s have received increasing attention due to their previously unrecognized property to attenuate obesity and its associated metabolic complications. In this review, we comprehensively evaluated the recent published scientific literature about the influence of T3s on obesity, with a particular emphasis on the signaling pathways involved. T3s have been demonstrated in animal models or human subjects to reduce fat mass, body weight, plasma concentrations of free fatty acid, triglycerides and cholesterol, as well as to improve glucose and insulin tolerance. Their mechanisms of action in adipose tissue mainly include (1) modulation of fat cell adipogenesis and differentiation; (2) modulation of energy sensing; (3) induction of apoptosis in preadipocytes and (4) modulation of inflammation. Studies have also been conducted to investigate the effects of T3s on other targets, e.g., the immune system, liver, muscle, pancreas and bone. Since δT3 and γT3 are regarded as the most active isomers among T3s, their clinical relevance to reduce obesity should be investigated in human trials

AT₁ angiotensin II receptor and novel non-AT₁, non-AT₂ angiotensin II/III binding site in brainstem cardiovascular regulatory centers of the spontaneously hypertensive rat

Spontaneously hypertensive rats (SHR) have an activated brain angiotensin system that contributes to the elevation of blood pressure in this animal model. Physiological and pharmacological studies suggest that hyperactivation of brain AT₁ angiotensin receptors is a major pathophysiological factor. Consistent with these observations, radioligand binding studies indicate widespread up-regulation of brain angiotensin receptors in SHR. One key brainstem site in which AT₁ receptor stimulation appears to contribute to the elevated blood pressure in SHR is the rostral ventrolateral medulla (RVLM). However, no quantitative comparison of AT₁ receptor binding in the RVLM has been made in SHR versus normotensive rats. A novel, non-AT₁, non-AT₂ binding site, specific for angiotensins II and III, has recently been discovered in the brain. To determine if radioligand binding to either AT₁ receptors or this novel angiotensin binding site is altered in the RVLM and other caudal brainstem regions of SHR, a quantitative densitometric autoradiographic comparison of radioligand binding in SHR versus normotensive Wistar-Kyoto rats was made. In both the RVLM and caudal ventrolateral medulla (CVLM) as well as dorsomedial medulla (DMM), there was increased expression of AT₁ receptor binding in SHR (13%, 9%, and 23%, respectively). Conversely, expression of the novel, non-AT₁, non-AT₂, angiotensin II and III binding site was decreased in the RVLM and DMM of SHR (37% and 13%, respectively). This increased AT₁ receptor binding in the RVLM may contribute to the hypertension of SHR. Reduced radioligand binding to the novel, non-AT₁, non-AT₂, angiotensin binding site in the RVLM of SHR may indicate a role for this binding site to reduce blood pressure via its interactions with angiotensins II and III

Optimized CyberKnife Lung Treatment: Effect of Fractionated Tracking Volume Change on Tracking Results

Objectives. To explore the impact of volume change in the fractionated tracking of stereotactic radiotherapy on the results of synchronous, respiratory tracking algorithm using CyberKnife. Methods. A total of 38 lung tumor patients receiving stereotactic radiotherapy at our center from March 2018 to October 2019 were counted. Photoshop CS4 image processing software was used to obtain the pixels and the average value of brightness of the tracking volume in the image and calculate the grayscale within the contour of the tracking volume on the real-time X-ray image. At the same time, parameters of the synchronous respiratory tracking algorithm of the fractional CyberKnife were extracted for comparison between the volume of image-guided image tracking and the number of fractions during stereotactic radiotherapy. We also analyzed the relationship between fraction tumor location and characteristics and the calculated results of synchronous respiratory tracking by CyberKnife. Results. There were no significant differences between the first four fractions (p>0.05) for left lung lesions and no significant differences between the first five fractions for right lung lesions (p≥0.05). For peripheral lung cancer, longer fractional treatment led to greater variation in grayscale (G-A: >4 fractions p4 fractions p0.7, p4 fractions were advised to reevaluate with simulated CT and replan. For tumors with small diameter and low density, the imaging changes of volume should be closely followed during treatment. For left lung and central lung cancer, carefully select the synchronous tracking treatment with 2-view

Bumetanide increases Cl--dependent short-circuit current in late distal colon: Evidence for the presence of active electrogenic Cl- absorption.

Mammalian colonic epithelia consist of cells that are capable of both absorbing and secreting Cl-. The present studies employing Ussing chamber technique identified two opposing short-circuit current (Isc) responses to basolateral bumetanide in rat distal colon. Apart from the transepithelial Cl--secretory Isc in early distal colon that was inhibited by bumetanide, bumetanide also stimulated Isc in late distal colon that had not previously been identified. Since bumetanide inhibits basolateral Na+-K+-2Cl- cotransporter (NKCC) in crypt cells and basolateral K+-Cl- cotransporter (KCC) in surface epithelium, we proposed this stimulatory Isc could represent a KCC-mediated Cl- absorptive current. In support of this hypothesis, ion substitution experiments established Cl- dependency of this absorptive Isc and transport inhibitor studies demonstrated the involvement of an apical Cl- conductance. Current distribution and RNA sequencing analyses revealed that this Cl- absorptive Isc is closely associated with epithelial Na+ channel (ENaC) but is not dependent on ENaC activity. Thus, inhibition of ENaC by 10 μM amiloride or benzamil neither altered the direction nor its activity. Physiological studies suggested that this Cl- absorptive Isc senses dietary Cl- content; thus when dietary Cl- was low, Cl- absorptive Isc was up-regulated. In contrast, when dietary Cl- was increased, Cl- absorptive Isc was down-regulated. We conclude that an active Cl- extrusion mechanism exists in ENaC-expressing late distal colon and likely operates in parallel with ENaC to facilitate NaCl absorption