ROS-Suppression Nanoplatform Combined Activation of STAT3/Bcl-2 Pathway for Preventing Myocardial Infarction in Mice.

Myocardial infarction (MI) is the leading cause of death worldwide. The most effective way to treat myocardial infarction is to rescue ischemic cardiomyocytes. After an ischemic event, the overproduction of reactive oxygen species (ROS) is a key driver of myocardial injury. The produced ROS affects mitochondrial function and induces apoptosis in cardiomyocytes. This was accomplished by constructing platelet-membrane-encapsulated ROS-responsive drug-releasing nanoparticles (PMN@NIC-MalNPs) to deliver malonate and niclosamide (NIC). The results revealed that PMN@NIC-MalNPs degraded and released malonate and niclosamide in a high-level ROS microenvironment, effectively reducing the oxidative stress and apoptosis rate. By enhancing basal mitochondrial oxygen consumption rate (OCR), adenosine triphosphate (ATP) production, and spare respiratory capacity (SRC) in vitro, reduced the oxidative stress levels and restored mitochondrial function. In vivo studies revealed that the PMN@NIC-MalNPs improved cardiac dysfunction, inhibited succinate dehydrogenase (SDH) activity, increased ATP production, and reduced the myocardial infarct size in myocardial infarction model mice. Further, transcriptome analysis and Western blot revealed that PMN@NIC-MalNPs prevented apoptosis by activating the expressions of the signal transducer and activator of transcription 3 (STAT3) and Bcl-2, and inhibiting the expression of Bax. Thus, this study provides a novel therapeutic solution for treating myocardial infarction and predicting the viability of an antioxidant and antiapoptotic therapeutic solution in the treatment of myocardial injury.

Ischemia-Selective Cardioprotection by Malonate for Ischemia/Reperfusion Injury.

BACKGROUND: Inhibiting SDH (succinate dehydrogenase), with the competitive inhibitor malonate, has shown promise in ameliorating ischemia/reperfusion injury. However, key for translation to the clinic is understanding the mechanism of malonate entry into cells to enable inhibition of SDH, its mitochondrial target, as malonate itself poorly permeates cellular membranes. The possibility of malonate selectively entering the at-risk heart tissue on reperfusion, however, remains unexplored. METHODS: C57BL/6J mice, C2C12 and H9c2 myoblasts, and HeLa cells were used to elucidate the mechanism of selective malonate uptake into the ischemic heart upon reperfusion. Cells were treated with malonate while varying pH or together with transport inhibitors. Mouse hearts were either perfused ex vivo (Langendorff) or subjected to in vivo left anterior descending coronary artery ligation as models of ischemia/reperfusion injury. Succinate and malonate levels were assessed by liquid chromatography-tandem mass spectrometry LC-MS/MS, in vivo by mass spectrometry imaging, and infarct size by TTC (2,3,5-triphenyl-2H-tetrazolium chloride) staining. RESULTS: Malonate was robustly protective against cardiac ischemia/reperfusion injury, but only if administered at reperfusion and not when infused before ischemia. The extent of malonate uptake into the heart was proportional to the duration of ischemia. Malonate entry into cardiomyocytes in vivo and in vitro was dramatically increased at the low pH (≈6.5) associated with ischemia. This increased uptake of malonate was blocked by selective inhibition of MCT1 (monocarboxylate transporter 1). Reperfusion of the ischemic heart region with malonate led to selective SDH inhibition in the at-risk region. Acid-formulation greatly enhances the cardioprotective potency of malonate. CONCLUSIONS: Cardioprotection by malonate is dependent on its entry into cardiomyocytes. This is facilitated by the local decrease in pH that occurs during ischemia, leading to its selective uptake upon reperfusion into the at-risk tissue, via MCT1. Thus, malonate's preferential uptake in reperfused tissue means it is an at-risk tissue-selective drug that protects against cardiac ischemia/reperfusion injury.

Succinate accumulation contributes to oxidative stress and iron accumulation in pentylenetetrazol-induced epileptogenesis and kainic acid-induced seizure.

This study explored the role of succinate accumulation in the oxidative stress and iron accumulation in both pentylenetetrazol (PTZ)-induced epileptogenesis and kainic acid (KA)-induced status epilepticus (SE). The levels of succinate, oxidative stress, iron content, iron-related protein expression, and the severity of neuronal injury and seizures were measured in both models. We found that increased concentrations of succinate were associated with increased levels of oxidative stress, iron content, iron regulator protein, and iron importer divalent metal transporter 1, as well as decreased levels of iron exporter ferropotin 1. Aggravated neuronal injury was observed in the hippocampi and cortices of both models. The cell-permeable molecule dimethyl malonate (DM), a competitive inhibitor of succinate dehydrogenase (SDH), significantly attenuated succinate accumulation, reduced the oxidative stress and iron levels, and mitigated the severity of the seizures and neuronal injury. Our results thus indicate that the accumulation of succinate due to the reverse catalysis of SDH may exacerbate oxidative stress and thus induce iron accumulation and neuronal injury in both models. Targeting succinate accumulation may achieve neuroprotective and anti-seizure effects.

Malonate Promotes Adult Cardiomyocyte Proliferation and Heart Regeneration.

BACKGROUND: Neonatal mouse cardiomyocytes undergo a metabolic switch from glycolysis to oxidative phosphorylation, which results in a significant increase in reactive oxygen species production that induces DNA damage. These cellular changes contribute to cardiomyocyte cell cycle exit and loss of the capacity for cardiac regeneration. The mechanisms that regulate this metabolic switch and the increase in reactive oxygen species production have been relatively unexplored. Current evidence suggests that elevated reactive oxygen species production in ischemic tissues occurs as a result of accumulation of the mitochondrial metabolite succinate during ischemia via succinate dehydrogenase (SDH), and this succinate is rapidly oxidized at reperfusion. Mutations in SDH in familial cancer syndromes have been demonstrated to promote a metabolic shift into glycolytic metabolism, suggesting a potential role for SDH in regulating cellular metabolism. Whether succinate and SDH regulate cardiomyocyte cell cycle activity and the cardiac metabolic state remains unclear. METHODS: Here, we investigated the role of succinate and SDH inhibition in regulation of postnatal cardiomyocyte cell cycle activity and heart regeneration. RESULTS: Our results demonstrate that injection of succinate into neonatal mice results in inhibition of cardiomyocyte proliferation and regeneration. Our evidence also shows that inhibition of SDH by malonate treatment after birth extends the window of cardiomyocyte proliferation and regeneration in juvenile mice. Remarkably, extending malonate treatment to the adult mouse heart after myocardial infarction injury results in a robust regenerative response within 4 weeks after injury via promoting adult cardiomyocyte proliferation and revascularization. Our metabolite analysis after SDH inhibition by malonate induces dynamic changes in adult cardiac metabolism. CONCLUSIONS: Inhibition of SDH by malonate promotes adult cardiomyocyte proliferation, revascularization, and heart regeneration via metabolic reprogramming. These findings support a potentially important new therapeutic approach for human heart failure.

Cardioprotective effect of succinate dehydrogenase inhibition in rat hearts and human myocardium with and without diabetes mellitus.

Ischemia reperfusion (IR) injury may be attenuated through succinate dehydrogenase (SDH) inhibition by dimethyl malonate (DiMAL). Whether SDH inhibition yields protection in diabetic individuals and translates into human cardiac tissue remain unknown. In isolated perfused hearts from 24 weeks old male Zucker diabetic fatty (ZDF) and age matched non-diabetic control rats and atrial trabeculae from patients with and without diabetes, we compared infarct size, contractile force recovery and mitochondrial function. The cardioprotective effect of a 10 minutes DiMAL administration prior to global ischemia and ischemic preconditioning (IPC) was evaluated. In non-diabetic hearts exposed to IR, DiMAL 0.1 mM reduced infarct size compared to IR (55 ± 7% vs. 69 ± 6%, p < 0.05). Mitochondrial respiration was reduced by DiMAL 0.6 mM compared to sham and DiMAL 0.1 mM (p < 0.05). In diabetic hearts an increased concentration of DiMAL (0.6 mM) was required for protection compared to IR (64 ± 13% vs. 79 ± 8%, p < 0.05). Mitochondrial function remained unchanged. In trabeculae from humans without diabetes, IPC and DiMAL improved contractile force recovery compared to IR (43 ± 12% and 43 ± 13% vs. 23 ± 13%, p < 0.05) but in patients with diabetes only IPC provided protection compared to IR (51 ± 15% vs. 21 ± 8%, p < 0.05). Neither IPC nor DiMAL modulated mitochondrial respiration in patients. Cardioprotection by SDH inhibition is possible in human tissue, but depends on diabetes status. The narrow therapeutic range and discrepancy in respiration between experimental and human studies may limit clinical translation.

Protection against cardiac ischemia-reperfusion injury by hypothermia and by inhibition of succinate accumulation and oxidation is additive.

Hypothermia induced at the onset of ischemia is a potent experimental cardioprotective strategy for myocardial infarction. The aim of our study was to determine whether the beneficial effects of hypothermia may be due to decreasing mitochondria-mediated mechanisms of damage that contribute to the pathophysiology of ischemia/reperfusion injury. New Zealand male rabbits were submitted to 30 min of myocardial ischemia with hypothermia (32 °C) induced by total liquid ventilation (TLV). Hypothermia was applied during ischemia alone (TLV group), during ischemia and reperfusion (TLV-IR group) and normothermia (Control group). In all the cases, ischemia was performed by surgical ligation of the left anterior descending coronary artery and was followed by 3 h of reperfusion before assessment of infarct size. In a parallel study, male C57BL6/J mice underwent 30 min myocardial ischemia followed by reperfusion under either normothermia (37 °C) or conventionally induced hypothermia (32 °C). In both the models, the levels of the citric acid cycle intermediate succinate, mitochondrial complex I activity were assessed at various times. The benefit of hypothermia during ischemia on infarct size was compared to inhibition of succinate accumulation and oxidation by the complex II inhibitor malonate, applied as the pro-drug dimethyl malonate under either normothermic or hypothermic conditions. Hypothermia during ischemia was cardioprotective, even when followed by normothermic reperfusion. Hypothermia during ischemia only, or during both, ischemia and reperfusion, significantly reduced infarct size (2.8 ± 0.6%, 24.2 ± 3.0% and 49.6 ± 2.6% of the area at risk, for TLV-IR, TLV and Control groups, respectively). The significant reduction of infarct size by hypothermia was neither associated with a decrease in ischemic myocardial succinate accumulation, nor with a change in its rate of oxidation at reperfusion. Similarly, dimethyl malonate infusion and hypothermia during ischemia additively reduced infarct size (4.8 ± 2.2% of risk zone) as compared to either strategy alone. Hypothermic cardioprotection is neither dependent on the inhibition of succinate accumulation during ischemia, nor of its rapid oxidation at reperfusion. The additive effect of hypothermia and dimethyl malonate on infarct size shows that they are protective by distinct mechanisms and also suggests that combining these different therapeutic approaches could further protect against ischemia/reperfusion injury during acute myocardial infarction.

Effect of Promising Antitumor Phenolic Antioxidant Anphen Sodium on the BCL-2 Family Proteins.

The proapoptotic effect of anphen (the effect on the level of the antiapoptotic protein Bcl-2) was investigated by immunoblotting. Incubation of Lewis carcinoma cell suspension with anphen at a concentration of 10-6 M for 0-3 h caused a 80% reduction in the level of the Bcl-2 protein and its homodimer. In vivo, when administered for 4 days to outbred mice, anphen (10-4 M) induced a decrease in the level of the Bcl-2 homodimer in the spleen cells by 20% and an increase in the content of the Bad protein (apoptosis activator) and the Bcl-XL protein. The antitumor effect of anphen may be due to blocking the hydrophobic pocket of the Bcl-2 protein.

Targeting SLC25A10 alleviates improved antioxidant capacity and associated radioresistance of cancer cells induced by chronic-cycling hypoxia.

High tumor heterogeneity and increased therapy resistance acquired in a hypoxic tumor microenvironment remain major obstacles to successful radiotherapy. Others and we have shown that adaptation of cancer cells to cycling severe hypoxia and intermittent reoxygenation stress (chronic-cycling hypoxia) increases cellular antioxidant capacity thereby supporting resistance to chemotherapy and radiotherapy. Here we explored the involvement of antioxidant-associated mitochondrial transport-systems for maintenance of redox-homeostasis in adaptation to chronic-cycling hypoxia and associated radioresistance. Genetic or pharmacological inhibition of the mitochondrial dicarboxylate carrier (SLC25A10) or the oxoglutarate-carrier (SLC25A11) increased the cytotoxic effects of ionizing radiation (IR). But only targeting of SLC25A10 was effective in overcoming chronic-cycling hypoxia-induced enhanced death resistance in vitro and in vivo by disturbing increased antioxidant capacity. Furthermore, in silico analysis revealed that overexpression of SLC25A10 but not SLC25A11 is associated with reduced overall survival in lung- and breast-cancer patients. Our study reveals a role of SLC25A10 in supporting both, redox- and energy-homeostasis, ensuring radioresistance of cancer cells with tolerance to chronic-cycling hypoxia thereby proposing a novel strategy to overcome a mechanism of hypoxia-induced therapy resistance with potential clinical relevance regarding decreased patient survival.

Mechanism of action of hypoglycemic effects of an intestine-specific inhibitor of microsomal triglyceride transfer protein (MTP) in obese rats.

Diminished insulin sensitivity in the peripheral tissues and failure of pancreatic beta cells to secrete insulin are known major determinants of type 2 diabetes mellitus. JTT-130, an intestine-specific microsomal transfer protein inhibitor, has been shown to suppress high fat-induced obesity and ameliorate impaired glucose tolerance while enhancing glucagon-like peptide-1 (GLP-1) secretion. We investigated the effects of JTT-130 on glucose metabolism and elucidated the mechanism of action, direct effects on insulin sensitivity and glucose-stimulated insulin secretion in a high fat diet-induced obesity rat model. Male Sprague Dawley rats fed a high-fat diet were treated with a single administration of JTT-130. Glucose tolerance, hyperglycemic clamp and hyperinsulinemic-euglycemic testing were performed to assess effects on insulin sensitivity and glucose-stimulated insulin secretion, respectively. Plasma GLP-1 and tissue triglyceride content were also determined under the same conditions. A single administration of JTT-130 suppressed plasma glucose elevations after oral glucose loading and increased the disposition index while elevating GLP-1. JTT-130 also enhanced glucose-stimulated insulin secretion in hyperglycemic clamp tests, whereas increased insulin sensitivity was observed in hyperinsulinemic-euglycemic clamp tests. Single-dose administration of JTT-130 decreased lipid content in the liver and skeletal muscle. JTT-130 demonstrated acute and direct hypoglycemic effects by enhancing insulin secretion and/or insulin sensitivity.

Bumadizone calcium dihydrate microspheres compressed tablets for colon targeting: formulation, optimization and in vivo evaluation in rabbits.

The objective of this study was the development of a colon-targeted microspheres which were compressed into tablets containing the non-steroidal anti-inflammatory bumadizone calcium hemihydrate. [corrected]. A 3(2) full factorial design was adopted for the evaluation of the prepared microspheres. The effect of two independent variables namely polymer type (Eudragit RS100, ethyl cellulose and cellulose acetate butyrate), and drug: polymer ratio (1:1, 9:1 and 18:1) was studied on the entrapment efficiency and in vitro drug release for 12 h. Colon targeting aims to minimize the release of the drug off target area (pH 1.2 and 6.8) and to maximize the release of the drug in target area (pH 7.4). Candidate formulae were compressed into core tablets and colon targeting was achieved using the enzyme-dependent polymer (pectin) as coat in three different concentrations 50, 75 and 90%. Candidate formula F15 (microspheres prepared using BDZ:CAB in a ratio of 18:1 and compressed into tablets using 50% pectin and 50% Avicel in the coat) was able to adequately modulate drug release avoiding drug release in the gastric ambient, and reaching the colonic targeting where 99.7% release was achieved within 12 h following zero-order model. In vivo studies showed that F15 achieved significant decrease in myeloperoxidase activity and inflammation with delayed Tmax (4 h) and lower Cmax (2700 ng/ml) when compared to marketed product.

Correlation Between Radiographic Area and Immunolocation of MMP-2 and MMP-9 in Unilocular Radiographic Lesions

Unilocular bone cysts are the most common entities affecting the maxillofacial region. The mechanism of proliferation and expansion remains unclear. Metalloproteinases (MMPs) are associated to diverse pathological conditions. The aim of the present study was to correlate the radiographic aspect (area) and the presence of MMP-2 and MMP-9 in dentigerous cysts, radicular cysts and keratocystic odontogenic tumors. The radiographic area of each lesion was calculated using the mathematical formula of the ellipse area. All specimens were subjected to immunohistochemical analysis for these enzymes. The average radiographic area was 284.17 mm2, 235.81 mm2 and 381.81 mm2, respectively. Statistical analyses revealed no association between the immunoreactivity of MMPs and radiographic area of the lesions in all pathologies studied, except for MMP-2 and radicular cysts, for which smaller lesions had increased immunostaining for this enzyme. The results demonstrate that quantities of MMP-2 and MMP-9 are especially involved with dentigerous and radicular cysts in expansion, whereas these enzymes seem to be related to the biological behavior of keratocystic odontogenic tumors, indicating invasion and cell proliferation. Moreover, there is an inverse association between MMP-2 and MMP-9 in keratocystic odontogenic tumors (p=0.03; rs=-0.660), indicating activity in different regions.

Cistos ósseos uniloculares são as entidades mais comuns que afetam a região maxilofacial. O mecanismo de proliferação e expansão permanece obscuro. As metaloproteinases (MMPs) estão associadas a diversas condições patológicas. O objetivo do presente estudo foi correlacionar o aspecto radiográfico (área) e a presença de MMP-2 e MMP-9 em cistos dentígeros, cistos radiculares e tumores odontogênicos queratocísticos. A área radiográfica de cada lesão foi calculada usando a fórmula matemática da área de elipse. Todas as amostras foram submetidas à análise imunoistoquímica para estas enzimas. A área radiográfica média foi de 284,17 mm2, 235,81 mm2 e 381,81 mm2, respectivamente. As análises estatísticas não mostraram associação entre a imunorreatividade de MMPs e área radiográfica das lesões em todas as patologias estudadas, exceto para MMP-2 e cistos radiculares, nas quais as lesões menores tinham maior imunomarcação para esta enzima. Os resultados demonstraram que a quantidade de imunomarcação da MMP-2 e MMP-9 estão envolvidos com cistos dentígeros e radiculares na expansão óssea, ao passo que estas enzimas parecem estar relacionados com o comportamento biológico dos tumores odontogénicos queratocísticos, indicando invasão e proliferação celular. Além disso, há uma relação inversa entre a MMP-2 e MMP-9 em tumores odontogénicos queratocísticos (p=0,03; rs= -0,660), indicando atividade em diferentes regiões.

In vivo evaluation of 1-benzyl-4-aminoindole-based thyroid hormone receptor ß agonists: importance of liver selectivity in drug discovery.

We recently reported that the novel thyroid hormone receptor ß (TRß) selective agonists SKL-12846 and SKL-13784 reduce blood cholesterol levels without affecting thyroid-stimulating hormone (TSH) in cholesterol-fed rats. Our aim in this study was to elucidate what sets apart these SKL-compounds as TRß agonists with no effect on TSH. To this end, we determined SKL-compounds pharmacokinetics and tissue distribution in normal rats and compared them to those of GC-1, a liver-selective TRß agonist with concomitant effect on TSH. The present study explains why SKL-12846 and SKL-13784 have beneficial effects on lowering lipids without affecting heart rate and TSH production at the therapeutic dose in cholesterol-fed rats. In addition, we found that SKL-13784 shows no sign of escape phenomenon in fructose-fed rats. These results demonstrate the advantages of extremely high liver specificity to TRß agonists. However, SKL-13784 has been found significantly to reduce endogenous T4 levels at doses lower than its lipid-lowering dose, which may raise concerns over this compound's ability to alter thyroid hormone metabolism in the liver. While the mechanism by which SKL-13784 reduces endogenous T4 levels is still unclear, our results would help design better liver-selective TRß modulators.

JTT-130, a novel intestine-specific inhibitor of microsomal triglyceride transfer protein, improves hyperglycemia and dyslipidemia independent of suppression of food intake in diabetic rats.

We investigated the effects of JTT-130 on glucose and lipid metabolism independent of the suppression of feeding by comparing with pair-fed animals. Male Zucker diabetic fatty (ZDF) rats were divided into control, JTT-130 treatment, and pair-fed groups. The rats were fed with a regular powdered diet with or without JTT-130 as a food admixture for 6 weeks. We compared the effects on glucose and lipid metabolism in JTT-130 treatment group with those in pair-fed group. RESULTS. Hyperglycemia in ZDF rats was prevented in both JTT-130 treatment and pair-fed groups, but the prevention in pair-fed group became poor with time. Moreover, reduction in plasma cholesterol levels was observed only in JTT-130 treatment group. JTT-130 treatment group showed improved glucose tolerance at 5 weeks after treatment and significant elevation of portal glucagon-like peptide-1 (GLP-1) levels. The hepatic lipid content in JTT-130 treatment group was decreased as compared with pair-fed group. Furthermore, pancreatic protection effects, such as an increase in pancreatic weight and an elevation of insulin-positive area in islets, were observed after JTT-130 treatment. CONCLUSIONS. JTT-130 improves hyperglycemia and dyslipidemia via a mechanism independent of suppression of food intake, which is ascribed to an enhancement of GLP-1 secretion and a reduction of lipotoxicity.

Combination therapy of an intestine-specific inhibitor of microsomal triglyceride transfer protein and peroxisome proliferator-activated receptor γ agonist in diabetic rat.

We investigated effects on glucose and lipid metabolism in combination of JTT-130, a novel intestine-specific microsomal triglyceride transfer protein (MTP) inhibitor, and pioglitazone, peroxisome proliferator-activated receptor (PPAR) γ agonist. Male Zucker diabetic fatty rats were divided into 4 groups: control group, JTT-130 treatment group, pioglitazone treatment group, and combination group. The Zucker diabetic fatty rats were fed a regular powdered diet with JTT-130 and/or pioglitazone as a food admixture for 6 weeks. Effects on glucose and lipid metabolism were compared mainly between JTT-130 treatment group and combination group. JTT-130 treatment showed good glycemic control, while the plasma glucose and glycated hemoglobin levels in combination group were significantly decreased as compared with those JTT-130 treatment group. The reduction in the plasma triglyceride and free fatty acid levels in combination group was higher than that in JTT-130 treatment group, and glucose utilization was significantly elevated in adipose tissues. In Zucker diabetic fatty rats, combination treatment of JTT-130 and pioglitazone showed better glycemic control and a strong hypolipidemic action with an enhancement of insulin sensitivity. Combination therapy of MTP inhibitor and PPAR γ agonist might be more useful in the treatment of type 2 diabetes accompanied with obesity and insulin resistance.

Mitochondrial triglyceride transfer protein inhibition: new achievements in the treatment of dyslipidemias.

Current lipid-lowering drugs are often unable to achieve low density lipoprotein cholesterol (LDL-C) goals. Moreover, despite LDL-C lowering mostly by statins, a considerable residual vascular risk remains. This is partly associated with atherogenic dyslipidemia where apolipoprotein (apo) B-containing lipoproteins predominate. Mitochondrial Triglyceride (TG) transfer protein (MTP) is a key enzyme for apoB-containing lipoprotein assembly and secretion. This is mostly attributed to its capacity to transfer lipid components (TGs, cholesterol esters and phospholipids) to the endoplasmic reticulum lumen, where these lipoproteins are assembled. Several agents were developed to inhibit MTP wherever it is expressed, namely the liver and/or the intestine. Liver-specific MTP inhibitors reduce secretion of very low density lipoproteins (VLDL) mostly containing apoB100, while the intestine-specific ones reduce secretion of chylomicrons containing apoB48. These drugs can significantly reduce total cholesterol, LDL-C, TGs, VLDL cholesterol, as well as apoB levels in vivo. They may also exert anti-atherosclerotic and insulin-sensitizing effects. Limited clinical data suggest that these compounds can also improve the serum lipid profile in patients with homozygous familial hypercholesterolemia (HoFH). The accumulation of unsecreted fat in the liver and intestinal lumen is associated with elevation of aminotransferases and steatorrhea. Liver steatosis can be avoided by the use of intestine-specific MTP inhibitors, while steatorrhea by low-fat diet. Future indications for these developing drugs may include dyslipidemia associated with insulin resistant states, familial combined hyperlipidemia and HoFH. Future clinical trials are warranted to assess the efficacy and safety of MTP inhibitors in various clinical states.

JTT-130, a novel intestine-specific inhibitor of microsomal triglyceride transfer protein, ameliorates impaired glucose and lipid metabolism in Zucker diabetic fatty rats.

AIM: Microsomal triglyceride transfer protein (MTP) takes part in the mobilization of triglyceride-rich lipoproteins from enterocytes and hepatocytes. We investigated the effects of JTT-130, a novel intestine-specific MTP inhibitor, on impaired glucose and lipid metabolism in Zucker diabetic fatty (ZDF) rats. METHODS: Male ZDF rats were fed a regular powdered diet with or without JTT-130 as a food admixture (0.01-0.02%) for 6 weeks. Food intake, body weight, blood biochemical parameters, fecal lipid contents, hepatic lipid contents, tissue mRNA levels and glucose utilization in adipose tissues were assessed. An intraperitoneal glucose tolerance test (IPGTT) and histological analysis of the pancreas were performed. RESULTS: JTT-130 treatment decreased food intake, glycated hemoglobin, plasma levels of glucose, triglycerides and total cholesterol, hepatic levels of triglycerides and cholesterol and hepatic mRNA levels of glucose-6-phosphatase, phosphoenolpyruvate carboxykinase and fructose-1,6-bisphosphatase. JTT-130 treatment increased fecal levels of free fatty acids and cholesterol, plasma levels of glucagon-like peptide-1 and peptide YY, mRNA levels of glucose transporter 4 (GLUT4) and lipoprotein lipase in adipose tissues and GLUT4 in muscle and glucose utilization in adipose tissues. Plasma insulin decreased after 2 weeks and increased after 4 weeks of JTT-130 treatment. Plasma glucose in the JTT-130-treated rats was lower with higher plasma insulin than in the control rats during the IPGTT. The islets of the JTT-130-treated rats were larger and contained more insulin than those of the control rats. CONCLUSIONS: JTT-130 ameliorates impaired glucose and lipid metabolism in the ZDF rats thereby suggesting that JTT-130 could be useful for prevention and treatment of type 2 diabetes.

The thyromimetic T-0681 protects from atherosclerosis.

This report describes studies in hyperlipidemic New Zealand White (NZW) rabbits investigating the impact of the liver-selective thyromimetic T-0681 on lipoprotein metabolism and the development of atherosclerosis. Prolonged treatment with T-0681 increased the hepatic expression of both LDL receptor and scavenger receptor class B, type I without affecting cholesteryl ester transfer protein activity. Upregulation of hepatic lipoprotein receptors was accompanied by a marked decrease of apolipoprotein B-containing lipoproteins, reflected by a 60% reduction of plasma cholesterol and a >70% reduction of plasma triglyceride levels. Most importantly, T-0681 reduced the development of atherosclerosis by 80% in NZW rabbits on high-cholesterol chow. Our data suggest that liver-selective thyromimetics, such as T-0681, may prove to be useful therapeutic agents against the development of atherosclerosis in humans.

Phase II clinical trial of SKI-2053R, a new platinum analog, in the treatment of patients with advanced gastric adenocarcinoma.

BACKGROUND: SKI-2053R (SK Chemicals, Kyungki-Do, South Korea) is a new platinum derivative with antitumor activity against various cell lines, including cisplatin-resistant tumor cell lines. Preclinical studies have suggested that it is less nephrotoxic than cisplatin. This study evaluated the efficacy and toxicity of SKI-2053R in the treatment of patients with advanced gastric adenocarcinoma. METHODS: Thirty-seven patients with advanced gastric adenocarcinoma that was unresectable or metastatic were treated. No prior chemotherapy or radiotherapy was allowed. Patients received SKI-2053R 360 mg/m(2) by 1-hour infusion on Day 1. After the first cycle, subsequent doses were adjusted according to the toxicity. Courses were repeated every 28 days. RESULTS: Thirty-five patients were evaluable for response and toxicity. Six patients achieved a major response (17%; 95% confidence interval, 8-33%); 2 were complete and 4 were partial responses. The median duration of response was 7.2 months, with a range of 1-20 months. Patients could tolerate the treatment without significant toxicity. No patients had Grade 3 or 4 toxicity. The most frequent toxicity was Grade 1 or 2 proteinuria (26% of cycles), but it was mild and transient. Leukopenia, thrombocytopenia, azotemia, nausea and vomiting, and neurotoxicity were not frequent. These low toxicity profiles indicated that the dose of SKI-2053R could be increased in future studies. CONCLUSIONS: SKI-2053R was active in the treatment of patients with gastric adenocarcinoma and had favorable toxicity profiles.

Phase II trial of a novel platinum analog, SKI 2053R, in patients with previously untreated extensive-stage small-cell lung cancer.

A phase II trial of a novel platinum analog, SKI 2053R, was performed in patients with previously untreated extensive-stage disease (ED) small-cell lung cancer (SCLC). SKI 2053R was administered at the dose of 400 mg/m2 every 3 to 4 weeks as a 1-h infusion. After the first cycle, the dose was escalated to 440 mg/m2 based on toxicity. Thirty-eight patients (31 male) were enrolled between June 1995 and August 1997. The median age was 61 years (range, 36-70 years). Six of 37 evaluable patients achieved a partial response (16.2%; 95% confidence interval [CI], 4.4-28.0%). The durations of response were 1.1, 1.5, 1.7, 1.9, 3.4, and 4.6 months. The estimated median survival time was 7.4 months (95% CI, 5.1-9.7 months). Grade 3 or 4 toxicities were not observed. Grade 1 to 2 leukopenia, anemia, and thrombocytopenia were seen in 5 of 68 cycles, 16 of 68, and 2 of 68, respectively. Nonhematologic toxicities included grade 1 to 2 nausea or vomiting (30 of 68 cycles), nephrotoxicity (27 of 68), and hepatotoxicity (13 of 68). SKI 2053R showed a modest antitumor activity with limited toxicities in patients with ED SCLC. Further clinical trials are warranted in SCLC with a higher dose of SKI 2053R.