Arrhythmogenic Peroxynitrite-Induced Alterations in Mammalian Heart Contractility and Its Prevention with Quercetin-Filled Liposomes

Current Advances in the Use of Nanophytomedicine Therapies for Human Cardiovascular Diseases

Considering the high prevalence of cardiovascular diseases (CVDs), the primary cause of death during the last several decades, it is necessary to develop proper strategies for the prevention and treatment of CVDs. Given the excessive side effects of current therapies, alternative therapeutic approaches like medicinal plants and natural products are preferred. Lower toxicity, chemical diversity, cost-effectiveness, and proven therapeutic potentials make natural products superior compared to other products. Nanoformulation methods improve the solubility, bioavailability, circulation time, surface area-to-volume ratio, systemic adverse side effects, and drug delivery efficiency of these medications. This study intended to review the functionality of the most recent nanoformulated medicinal plants and/or natural products against various cardiovascular conditions such as hypertension, atherosclerosis, thrombosis, and myocardial infarction. Literature review revealed that curcumin, quercetin, and resveratrol were the most applied natural products, respectively. Combination therapy, conjugation, or fabrication of nanoparticles and nanocarriers improved the applications and therapeutic efficacy of herbal- or natural-based nanoformulations. In the context of CVDs prevention and/or treatment, available data suggest that natural-based nanoformulations are considerably efficient, alone or in blend with other herbal/synthetic medicines. However, clinical trials are mandatory to elucidate the safety, cardioprotective effect, and mechanism of actions of nanophytomedicines.

Effect of dentin biomodification techniques on the stability of the bonded interface

Aim:

The aim of this study is to evaluate the effect of different bonding techniques ethanol wet bonding and dimethyl sulfoxide (DMSO) wet bonding and a novel collagen cross-linker Quercetin application on the durability of resin-dentin bond and observe the bonded interface under the scanning electron microscope (SEM).

Materials and Methods:

For shear bond strength testing, flat coronal dentin surfaces were prepared on 110 extracted human molars. Teeth were randomly divided into five experimental groups according to different surface pretreatments techniques. Group A was control group without any surface pretreatment. In Group B, ethanol wet bonding pretreatment was done before the application of adhesive. In Group C, DMSO wet bonding was done before the application of adhesive and in Groups D and E, Quercetin along with ethanol and Quercetin along with DMSO pretreatment, respectively, were done before adhesive application. Composite restorations were placed in all the samples. Twenty samples from each group were subjected to immediate and delayed (9 months) shear bond strength evaluation. In addition, two samples per group were subjected to the scanning electron microscopic analysis for the observation of resin-dentin interface.

Statistical Analysis:

Data collected were subjected to the statistical analysis using the one-way analysis of variance and post hoc Tukey's test at a significance level of P < 0.05.

Results:

Dentin pretreatment with all the techniques resulted in significantly higher resin-dentin bond strength after 9 months storage with DMSO group showing the highest bond strength values.

Conclusion:

It can be concluded that these biomodification techniques can improve the durability of the resin-dentin bond.

Mitochondrial and Sarcoplasmic Reticulum Interconnection in Cardiac Arrhythmia

Ca²⁺ plays a pivotal role in mitochondrial energy production, contraction, and apoptosis. Mitochondrial Ca²⁺-targeted fluorescent probes have demonstrated that mitochondria Ca²⁺ transients are synchronized with Ca²⁺ fluxes occurring in the sarcoplasmic reticulum (SR). The presence of specialized proteins tethering SR to mitochondria ensures the local Ca²⁺ flux between these organelles. Furthermore, communication between SR and mitochondria impacts their functionality in a bidirectional manner. Mitochondrial Ca²⁺ uptake through the mitochondrial Ca²⁺ uniplex is essential for ATP production and controlled reactive oxygen species levels for proper cellular signaling. Conversely, mitochondrial ATP ensures the proper functioning of SR Ca²⁺-handling proteins, which ensures that mitochondria receive an adequate supply of Ca²⁺. Recent evidence suggests that altered SR Ca²⁺ proteins, such as ryanodine receptors and the sarco/endoplasmic reticulum Ca²⁺ ATPase pump, play an important role in maintaining proper cardiac membrane excitability, which may be initiated and potentiated when mitochondria are dysfunctional. This recognized mitochondrial role offers the opportunity to develop new therapeutic approaches aimed at preventing cardiac arrhythmias in cardiac disease.

Size-Dependent Ability of Liposomes to Accumulate in the Ischemic Myocardium and Protect the Heart

Liposomes have the potential to be used for drug delivery. Meanwhile, liposome size may affect their accumulation in the target tissue. We investigated the myocardial accumulation of 2 populations of liposomes (∼70 and 110 nm diameter) during ischemia and their effect on ischemia/reperfusion injury. Isolated rat hearts were subjected to 30 minutes of low-flow ischemia with the liposomes, followed by 30 minutes of liposome-free reperfusion. The liposomes were loaded with the fluorescent dye Nile Red to assess their accumulation in the myocardium. The cardiac functional recovery during reperfusion was evaluated using force–velocity characteristics and coronary flow (CF). Reperfusion injury was evaluated by lactate dehydrogenase release. In addition, CF and contractility were assessed in hearts perfused normally with 70 nm liposomes. There was a 6- and 4-fold greater accumulation of the small liposomes in the myocardium and mitochondria, respectively, compared with the large liposomes. Importantly, even without any incorporated drugs, both populations of liposomes improved functional recovery and reduced lactate dehydrogenase release. However, the smaller liposomes showed significantly higher protective and vasodilatory effects during reperfusion than the larger particles. These liposomes also increased CF and contractility during normal perfusion. We suggest that the protective properties of the liposomes could be related to their membrane-stabilizing effect.

The environmental pollutant, polychlorinated biphenyls, and cardiovascular disease: a potential target for antioxidant nanotherapeutics

Despite production having stopped in the 1970s, polychlorinated biphenyls (PCBs) represent persistent organic pollutants that continue to pose a serious human health risk. Exposure to PCBs has been linked to chronic inflammatory diseases, such as cardiovascular disease, type 2 diabetes, obesity, as well as hepatic disorders, endocrine dysfunction, neurological deficits, and many others. This is further complicated by the PCB's strong hydrophobicity, resulting in their ability to accumulate up the food chain and to be stored in fat deposits. This means that completely avoiding exposure is not possible, thus requiring the need to develop intervention strategies that can mitigate disease risks associated with exposure to PCBs. Currently, there is excitement in the use of nutritional compounds as a way of inhibiting the inflammation associated with PCBs, yet the suboptimal delivery and pharmacology of these compounds may not be sufficient in more acute exposures. In this review, we discuss the current state of knowledge of PCB toxicity and some of the antioxidant and anti-inflammatory nanocarrier systems that may be useful as an enhanced treatment modality for reducing PCB toxicity.

The devastating effect of exposure to high irradiation dose on liver and the performance of synthesized nano-Hap in relieve the associated symptoms in rats

Ionizing radiation is one of the environmental factors that may contribute to liver dysfunction through a mechanism involving oxidative stress. This investigation studied the possible therapeutic effects of nano-HAp on hepatotoxicity in rats induced with gamma (γ) radiation. The study was carried out using 3 groups with 10 rats in each. Group 1 comprised the non-irradiated control rats, whereas the rats in groups 2 and 3 received a single dose of 10 Gy γ-radiation. The rats in group 3 were treated with nano-HAp [100 mg·(kg body mass)−1] once a week for 2 weeks starting the day after irradiation. The results showed that the rats exposed to γ-radiation had fragmented DNA, and significantly decreased levels of liver tissue enzymes such as paraoxonase 1, gamma glutamyl, alanine aminotransferase (ALT), and aspartate aminotransferase (AST). Pro-inflammatory factors such as interleukin (IL)-2, IL-6, tumor necrosis factor alpha (TNF-α), and interferon gamma (IFN-γ) in tissue were significantly increased compared with the controls. Also, exposure to γ-radiation significantly decreased the activity of superoxide dismutase and glutathione oxidase and increased lipid peroxidation in liver tissue. These effects were accompanied by severe histopathological changes to the hepatocytes. Intravenous injection of nano-HAp after irradiation has significant therapeutic potential against irradiation-induced liver damage because the treatment with nano-HAp restored antioxidant activity in the liver, antagonized the significant changes in the levels of IL-2, IL-6, TNF-α, IFN-γ, and restored the tissue level of paraoxonase 1, gamma glutamyl, ALT, and AST. Administering nano-HAp seemed to relieve the pathological changes induced by γ-radiation. Based on these results, it could be concluded that nano-HAp may have a therapeutic effect against liver dysfunction induced by γ-radiation through antagonizing the generation of free radicals and enhancing the antioxidant defense mechanisms.

Capsaicin Protects Cardiomyocytes against Anoxia/Reoxygenation Injury via Preventing Mitochondrial Dysfunction Mediated by SIRT1

Capsaicin (Cap) has been reported to have beneficial effects on cardiovascular system, but the mechanisms underlying these effects are still poorly understood. Apoptosis has been shown to be involved in mitochondrial dysfunction, and upregulating expression of SIRT1 can inhibit the apoptosis of cardiomyocytes induced by anoxia/reoxygenation (A/R). Therefore, the aim of this study was to test whether the protective effects of Cap against the injury to the cardiomyocytes are mediated by SIRT1. The effects of Cap with or without coadministration of sirtinol, a SIRT1 inhibitor, on changes induced by A/R in the cell viability, activities of lactate dehydrogenase (LDH), creatine phosphokinase (CPK), levels of intracellular reactive oxygen species (ROS), and mitochondrial membrane potential (MMP), related protein expression, mitochondrial permeability transition pore (mPTP) opening, and apoptosis rate in the primary neonatal rat cardiomyocytes were tested. Cap significantly increased the cell viability, upregulated expression of SIRT1 and Bcl-2, and decreased the LDH and CPK release, generation of ROS, loss of MMP, mPTP openness, activities of caspase-3, release of the cytochrome c, and apoptosis of the cardiomyocytes. Sirtinol significantly blocked the cardioprotective effects of Cap. The results suggest that the protective effects of Cap against A/R-induced injury to the cardiomyocytes are involved with SIRT1.

Cardioprotective effects of quercetin against ischemia-reperfusion injury are age-dependent

Quercetin, a polyphenolic compound present in various types of food, has been shown to exert beneficial effects in different cardiac as well as non-cardiac ischemia/reperfusion (I/R) models in adult animals. However, there is no evidence about the effects of quercetin on I/R injury in non-mature animals, despite the fact that efficiency of some interventions against I/R is age-dependent. This study was aimed to investigate the effects of chronic quercetin treatment on I/R injury in juvenile and adult rat hearts. Juvenile (4-week-old) as well as adult (12-week-old) rats were treated with quercetin (20 mg/kg/day) for 4 weeks, hearts were excised and exposed to 25-min global ischemia followed by 40-min reperfusion. Functional parameters of hearts and occurrence of reperfusion arrhythmias were registered to assess the cardiac function. Our results have shown that quercetin improved post-ischemic recovery of LVDP, as well as recovery of markers of contraction and relaxation, +(dP/dt)max and -(dP/dt)max, respectively, in juvenile hearts, but not in adult hearts. Quercetin had no impact on incidence as well as duration of reperfusion arrhythmias in animals of both ages. We conclude that the age of rats plays an important role in heart response to quercetin treatment in the particular dose and duration of the treatment. Therefore, the age of the treated subjects should be taken into consideration when choosing the dose of quercetin and duration of its application in prevention and/or treatment of cardiovascular diseases.

Effect of quercetin on apoptosis of PANC-1 cells

Purpose

To investigate the chemotherapeutic effect of quercetin against cancer cells, signaling pathway of apoptosis was explored in human pancreatic cells.

Methods

Various anticancer drugs including adriamycin, cisplatin, 5-fluorouracil (5-FU) and gemcitabine were used. Cell viability was measured by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphe-nyltetra zolium bromide assay. Apoptosis was determined by 4'-6-diamidino-2-phenylindole nuclei staining and flow cytometry in PANC-1 cells treated with 50 µg/mL quercetin for 24 hours. Expression of endoplas mic reticulum (ER) stress mediators including, Grp78/Bip, p-PERK, PERK, ATF4, ATF6 and GADD153/CHOP proteins were measured by Western blot analysis. Mitochondrial membrane potential was measured by fluorescence staining with JC-1, rhodamine 123. Quercetin induced the apoptosis of PANC-1, which was characterized as nucleic acid and genomic DNA fragmentation, chromatin condensation, and sub-G0/G1 fraction of cell cycle increase. But not adriamycin, cisplatin, gemcitabine, and 5-FU. PANC-1 cells were markedly sensitive to quercetin.

Results

Treatment with quercetin resulted in the increased accumulation of intracellular Ca²⁺ ion. Treatment with quercetin also increased the expression of Grp78/Bip and GADD153/CHOP protein and induced mitochondrial dysfunction. Quercetin exerted cytotoxicity against human pancreatic cancer cells via ER stress-mediated apoptotic signaling including reactive oxygen species production and mitochondrial dysfunction.

Conclusion

These data suggest that quercetin may be an important modulator of chemosensitivity of cancer cells against anticancer chemotherapeutic agents.

Liposomal Antioxidants for Protection against Oxidant-Induced Damage

Reactive oxygen species (ROS), including superoxide anion, hydrogen peroxide, and hydroxyl radical, can be formed as normal products of aerobic metabolism and can be produced at elevated rates under pathophysiological conditions. Overproduction and/or insufficient removal of ROS result in significant damage to cell structure and functions. In vitro studies showed that antioxidants, when applied directly and at relatively high concentrations to cellular systems, are effective in conferring protection against the damaging actions of ROS, but results from animal and human studies showed that several antioxidants provide only modest benefit and even possible harm. Antioxidants have yet to be rendered into reliable and safe therapies because of their poor solubility, inability to cross membrane barriers, extensive first-pass metabolism, and rapid clearance from cells. There is considerable interest towards the development of drug-delivery systems that would result in the selective delivery of antioxidants to tissues in sufficient concentrations to ameliorate oxidant-induced tissue injuries. Liposomes are biocompatible, biodegradable, and nontoxic artificial phospholipid vesicles that offer the possibility of carrying hydrophilic, hydrophobic, and amphiphilic molecules. This paper focus on the use of liposomes for the delivery of antioxidants in the prevention or treatment of pathological conditions related to oxidative stress.

ATP-loaded liposomes for treatment of myocardial ischemia

A major obstacle to drug therapy for treatment of potential myocardial infarction is the limited access to the ischemic myocardium by drugs in an active form. Encouraging results have been reported with liposomes loaded with ATP in a variety of in vitro and in vivo models. We describe methods for optimized encapsulation of ATP in liposomes, enhancement of their effectiveness by increasing circulation time, and targeting of injured myocardial cells with surface attached antimyosin. In isolated ischemic rat hearts, ATP-loaded liposomes and ATP-loaded immunoliposomes effectively protected myocardium from ischemia/reperfusion damage as measured by systolic and diastolic functional improvements. In vivo, in rabbits with induced localized myocardial ischemia, liposomal encapsulation of ATP significantly diminished the proportion of ventricular muscle at risk that was irreversibly damaged during reperfusion. Therefore, ATP encapsulated in liposomes can provide an effective exogenous source for in vivo application which can protect ischemically damaged hearts.

Peroxynitrite formation mediates LPC-induced augmentation of cardiac late sodium currents

Lysophosphatidylcholine (LPC) accumulates in the ischaemic myocardium and is arrhythmogenic. We have examined the mechanisms underlying the effects of LPC on the late cardiac Na(+) current (I(L)Na). Na(+) currents were recorded in HEK293 cells expressing Na(V)1.5 and isolated rat ventricular myocytes. LPC enhanced recombinant I(L)Na, while it reduced peak Na(+) current. Computer modeling of human ventricular myocyte action potentials predicted a marked duration prolonging effect and arrhythmogenic potential due to these effects of LPC on peak and late currents. Enhancement of recombinant I(L)Na was suppressed by the antioxidant ascorbic acid and by the NADPH oxidase inhibitor DPI. Inhibitors of the mitochondrial electron transport chain (rotenone, TTFA and myxothiazol) were without effect on LPC responses. The superoxide donor pyrogallol was without effect on I(L)Na. Enhancement of I(L)Na was abrogated by the NOS inhibitors l-NAME and 7-nitroindazole, while LPC induced an l-NAME-sensitive production of NO, measured as enhanced DAF-FM fluorescence, in both HEK293 cells and ventricular myocytes. Despite this, the NO donors SNAP and SNP caused no change in I(L)Na. However, SNAP enhanced TTX-sensitive recombinant and native I(L)Na in the presence of pyrogallol, suggesting peroxynitrite formation as a mediator of the response to LPC. In support of this, the peroxynitrite scavenger FeTPPS prevented the response of I(L)Na to LPC. Peroxynitrite formation provides a novel mechanism by which LPC regulates the late cardiac Na(+) current.

Nitric oxide and peroxynitrite in health and disease

The discovery that mammalian cells have the ability to synthesize the free radical nitric oxide (NO) has stimulated an extraordinary impetus for scientific research in all the fields of biology and medicine. Since its early description as an endothelial-derived relaxing factor, NO has emerged as a fundamental signaling device regulating virtually every critical cellular function, as well as a potent mediator of cellular damage in a wide range of conditions. Recent evidence indicates that most of the cytotoxicity attributed to NO is rather due to peroxynitrite, produced from the diffusion-controlled reaction between NO and another free radical, the superoxide anion. Peroxynitrite interacts with lipids, DNA, and proteins via direct oxidative reactions or via indirect, radical-mediated mechanisms. These reactions trigger cellular responses ranging from subtle modulations of cell signaling to overwhelming oxidative injury, committing cells to necrosis or apoptosis. In vivo, peroxynitrite generation represents a crucial pathogenic mechanism in conditions such as stroke, myocardial infarction, chronic heart failure, diabetes, circulatory shock, chronic inflammatory diseases, cancer, and neurodegenerative disorders. Hence, novel pharmacological strategies aimed at removing peroxynitrite might represent powerful therapeutic tools in the future. Evidence supporting these novel roles of NO and peroxynitrite is presented in detail in this review.

Construction of rat calcineurin A alpha cDNA recombinant adenovirus vector and its identification

Rat calcineurin (CaN) A alpha isoform (Ppp3ca) cDNA recombinant adenovirus vector was constructed in order to explore the effect of CaN on the myocardium apoptosis induced by ischemia-reperfusion injury. Total RNA was isolated from the heart of the adult Wistar rat, and Ppp3ca CDS segment of approximate 1.59 kb size was amplified by reverse transcriptional PCR method. Ppp3ca cDNA segment was cloned into pMD18-T Simple vector for sequencing, and the right clone was named T-Ppp3ca. Ppp3ca cDNA segment obtained from T-Ppp3ca was ligated with pShuttle2-IRES-EGFP to construct a recombinant plasmid pShuttle2-Ppp3ca-IRES-EGFP. Ppp3ca-IRES-EGFP expression cassette containing CMV, Ppp3ca-IRES-EGFP and SV40 polyA DNA fragment (3.97 kb) obtained from pShuttle2-Ppp3ca-IRES-EGFP was connected with pAdeno-X backbone sequence to construct a recombinant plasmid pAdeno-Ppp3ca. After being identified by PCR and enzyme digestion, recombinant plasmid pAdeno-Ppp3ca was packaged in HEK293 cells. Supernatant of adenovirus from HEK293 cells was collected after a visible cytopathic effect (CPE) appeared. The DNA of the recombinant adenovirus was extracted with the standard method. The presence of the recombinant adenovirus was verified by PCR. The results showed that sequencing results verified that the PCR product of Ppp3ca gene was identical to GenBank. Agarose electrophoresis showed the bands of recombined plasmid pAdeno-Ppp3ca and the recombinant adenovirus identified by enzyme digestion and PCR were in the right range corresponding with expectation. It was concluded that the recombinant adenovirus carrying rat calcineurin A alpha (Ppp3ca) cDNA as well as a report gene-enhancer green fluorescent protein gene was successfully constructed in this experiment.