Cilostazol Inhibits Accumulation of Triglyceride in Aorta and Platelet Aggregation in Cholesterol-Fed Rabbits

Cilostazol is clinically used for the treatment of ischemic symptoms in patients with chronic peripheral arterial obstruction and for the secondary prevention of brain infarction. Recently, it has been reported that cilostazol has preventive effects on atherogenesis and decreased serum triglyceride in rodent models. There are, however, few reports on the evaluation of cilostazol using atherosclerotic rabbits, which have similar lipid metabolism to humans, and are used for investigating the lipid content in aorta and platelet aggregation under conditions of hyperlipidemia. Therefore, we evaluated the effect of cilostazol on the atherosclerosis and platelet aggregation in rabbits fed a normal diet or a cholesterol-containing diet supplemented with or without cilostazol. We evaluated the effects of cilostazol on the atherogenesis by measuring serum and aortic lipid content, and the lesion area after a 10-week treatment and the effect on platelet aggregation after 1- and 10-week treatment. From the lipid analyses, cilostazol significantly reduced the total cholesterol, triglyceride and phospholipids in serum, and moreover, the triglyceride content in the atherosclerotic aorta. Cilostazol significantly reduced the intimal atherosclerotic area. Platelet aggregation was enhanced in cholesterol-fed rabbits. Cilostazol significantly inhibited the platelet aggregation in rabbits fed both a normal diet and a high cholesterol diet. Cilostazol showed anti-atherosclerotic and anti-platelet effects in cholesterol-fed rabbits possibly due to the improvement of lipid metabolism and the attenuation of platelet activation. The results suggest that cilostazol is useful for prevention and treatment of atherothrombotic diseases with the lipid abnormalities

Hyperlipidemic Rabbit Models for Anti-Atherosclerotic Drug Development

Hyperlipidemia or dyslipidemia is a major risk factor for atherosclerotic diseases. Experimental animals play an important role in elucidating the molecular mechanisms of the pathophysiology of hyperlipidemia as well as in drug development. Rabbits are one of the most suitable models to study human hyperlipidemia because many features of the lipoprotein metabolism of rabbits are similar to those of humans such as LDL-rich lipoproteins in plasma, apolipoprotein B mRNA editing, and cholesteryl ester transfer protein. Currently, three types of rabbit models are commonly used for studying hyperlipidemia: (1) diet-induced hyperlipidemic rabbits, (2) spontaneous hyperlipidemic rabbits, and (3) gene-manipulated rabbits (transgenic and knockout rabbits). In this review, we give an overview of the features of hyperlipidemic rabbits and discuss the usefulness of rabbits for the development of anti-atherogenic drugs

Strategies for Highly Efficient Rabbit Sperm Cryopreservation

The rabbit is a valuable animal for both the economy and biomedical sciences. Sperm cryopreservation is one of the most efficient ways to preserve rabbit strains because it is easy to collect ejaculate repeatedly from a single male and inseminate artificially into multiple females. During the cooling, freezing and thawing process of sperms, the plasma membrane, cytoplasm and genome structures could be damaged by osmotic stress, cold shock, intracellular ice crystal formation, and excessive production of reactive oxygen species. In this review, we will discuss the progress made during the past years regarding efforts to minimize the cell damage in rabbit sperms, including freezing extender, cryoprotectants, supplements, and procedures

The Combined Administration of Vitamin C and Copper Induces a Systemic Oxidative Stress and Kidney Injury

Vitamin C (ascorbic acid; AA) and copper (Cu2+) are well used supplements with many health-promoting actions. However, when they are used in combination, the Fenton reaction occurs, leading to the formation of highly reactive hydroxyl radicals. Given that kidney is vulnerable to many toxicants including free radicals, we speculated that the in vivo administration of AA plus Cu2+ may cause oxidative kidney injury. The purpose of this study was to address this possibility. Mice were administered with AA and Cu2+, alone or in combination, via oral gavage once a day for various periods. Changes in the systemic oxidative status, as well renal structure and functions, were examined. The administration of AA plus Cu2+ elevated protein oxidation in serum, intestine, bladder, and kidney, as evidenced by the increased sulfenic acid formation and decreased level of free sulfhydryl groups (-SH). The systemic oxidative stress induced by AA plus Cu2+ was associated with a significant loss of renal function and structure, as indicated by the increased blood urea nitrogen (BUN), creatinine and urinary proteins, as well as glomerular and tubular cell injury. These effects of AA and Cu2+ were only observed when used in combination, and could be entirely prevented by thiol antioxidant NAC. Further analysis using cultured renal tubular epithelial cells revealed that AA plus Cu2+ caused cellular protein oxidation and cell death, which could be abolished by NAC and catalase. Moreover, coincubation of AA and Cu2+ led to H2O2 production. Collectively, our study revealed that a combined administration of AA and Cu2+ resulted in systemic oxidative stress and renal cell injury. As health-promoting supplements, AA and Cu2+ should not be used together

Development of Dietary Thiol Antioxidant via Reductive Modification of Whey Protein and Its Application in the Treatment of Ischemic Kidney Injury

Thiol antioxidants play important roles in cell and body defense against oxidative stress. In body fluid, albumin is the richest source of thiol antioxidants. One recent study showed that the reductive modification of thiol residues in albumin potentiated its antioxidative activity. Given that whey protein (WP) contains albumin and other thiol-active proteins, this property of WP could be exploited to develop novel thiol antioxidants. The aim of this study was to address this possibility. WP was reductively modified with dithiothreitol (DTT). The modified protein exhibited significantly elevated free sulfhydryl groups (-SH) and thiol antioxidative activity. It detoxified H2O2 and prevented H2O2-initiated protein oxidation and cell death in a -SH group-dependent way in vitro. In addition, it reacted with GSH/GSSG and altered the GSH/GSSG ratio via thiol–disulfide exchange. In vivo, oral administration of the reductively modified WP prevented oxidative stress and renal damage in a mouse model of renal injury caused by ischemia reperfusion. It significantly improved renal function, oxidation, inflammation, and cell injury. These protective effects were not observed in the WP control and were lost after blocking the -SH groups with maleimide. Furthermore, albumin, one of the ingredients of WP, also exhibited similar protective effects when reductively modified. In conclusion, the reductive modification of thiol residues in WP transformed it into a potent thiol antioxidant that protected kidneys from ischemia reperfusion injury. Given that oxidative stress underlies many life-threatening diseases, the reductively modified dietary protein could be used for the prevention and treatment of many oxidative-stress-related conditions, such as cardiovascular diseases, cancer, and aging

Phase I study of photodynamic therapy using talaporfin sodium and diode laser for local failure after chemoradiotherapy for esophageal cancer

Abstract Background Photodynamic therapy (PDT) is a less invasive and effective salvage treatment for local failure after chemoradiotherapy (CRT) for esophageal cancer, however it causes a high rate of skin phototoxicity and requires a long sun shade period. Talaporfin sodium is a rapidly cleared photosensitizer that is expected to have less phototoxicity. This study was undertaken to clarify the optimum laser fluence rate of PDT using talaporfin sodium and a diode laser for patients with local failure after CRT or radiotherapy (RT) for esophageal cancer. Methods This phase I, laser dose escalation study used a fixed dose (40 mg/m2) of intravenous talaporfin sodium administered 4 to 6 hours before irradiation in patients with local failure limited to T2 after CRT or RT (≥ 50 Gy). The primary endpoint was to assess the dose limiting toxicity (DLT) of PDT, and the secondary endpoints were to evaluate the adverse events and toxicity related to PDT. The starting fluence of the 664 nm diode laser was 50 J/cm2, with an escalation plan to 75 J/cm2 and 100 J/cm2. Results 9 patients with local failure after CRT or RT for ESCC were enrolled and treated in groups of 3 individuals to the third fluence level. No DLT was observed at any fluence level. Phototoxicity was not observed, but one subject had grade 1 fever, three had grade 1 esophageal pain, and 1 had grade 1 dysphagia. Five of 9 patients (55.6%) achieved a complete response after PDT. Conclusions PDT using talaporfin sodium and a diode laser was safe for local failure after RT in patients with esophageal cancer. The recommended fluence for the following phase II study is 100 J/cm2.</p