Growth inhibition of colon cancer cells by transfection of dominant-negative apoptosis signal-regulating kinase-1

Apoptosis signal-regulating kinase-1 (ASK-1) is an important molecule for the pro-apoptotic signaling. ASK-1 also contributes to the cellular survival for many types of cells. Thus, ASK-1 has a broad range of biological activities depending on the cell type. The present study assessed the role(s) of ASK-1 in colorectal cancer cells (HT-29) by using adenovirus vectors expressing wild-type (WT)-ASK-1 or dominant-negative (DN) mutant of ASK-1 and recombinant adenovirus containing the bacterial beta-galactosidase gene (Ad-LacZ), a negative control for Ad-DN-ASK-1. Selective phosphorylation of ASK-1 at Thr 845, a kinase domain site, but not Ser 83 nor 967 sites was induced by serum stimulation in a time-dependent manner. Transfection with Ad-DN-ASK-1 inhibited the serum-induced phosphorylation of p38 mitogen-activated protein kinase, a downstream molecule of ASK-1. Transfection with Ad-DN-ASK-1 diminished the serum-induced cell proliferation in a dose-dependent manner, whereas WT-ASK-1 increased it. Apoptosis assessed by Hoechst staining was induced in the Ad-DN-ASK-1 treated cells. In vivo transfection of Ad-DN-ASK-1 into tumor xenografts of HT-29 cells in nude mice significantly decreased the tumor volume on day 29. Cleaved caspase-3 was found in the tumors of DN-ASK-1 treated mice. We obtained the first evidence that DN-ASK-1 transfection exerted significant antitumor effects on colon cancer mediated by apoptosis.     

Cyanidin 3-glucoside ameliorates hyperglycemia and insulin sensitivity due to downregulation of retinol binding protein 4 expression in diabetic mice

Adipocyte dysfunction is strongly associated with the development of obesity and insulin resistance. It is accepted that the regulation of adipocytokine expression is one of the most important targets for the prevention of obesity and improvement of insulin sensitivity. In this study, we have demonstrated that anthocyanin (cyanidin 3-glucoside; C3G) which is a pigment widespread in the plant kingdom, ameliorates hyperglycemia and insulin sensitivity due to the reduction of retinol binding protein 4 (RBP4) expression in type 2 diabetic mice. KK-A(y) mice were fed control or control +0.2% of a C3G diet for 5 weeks. Dietary C3G significantly reduced blood glucose concentration and enhanced insulin sensitivity. The adiponectin and its receptors expression were not responsible for this amelioration. C3G significantly upregulated the glucose transporter 4 (Glut4) and downregulated RBP4 in the white adipose tissue, which is accompanied by downregulation of the inflammatory adipocytokines (monocyte chemoattractant protein-1 and tumor necrosis factor-alpha) in the white adipose tissue of the C3G group. These findings indicate that C3G has significant potency in an anti-diabetic effect through the regulation of Glut4-RBP4 system and the related inflammatory adipocytokines.     

An 88-year-old woman with symptoms of intoxication due to a small dose of digoxin]

An 88-year-old woman was admitted to our hospital because of palpitations, dyspnea, orthopnea and appetite loss. On admission, small crackles were heard on her lower back, and her liver was swollen. Chest rentogenogram showed cardiomegaly (cardio-thoracic ratio 65.5%) and bilateral pleural effusion. Electrocardiograms showed atrial fibrillation with an average heart rate of 95 per minute. Echocardiography revealed mitral stenosis. Because the patient was considered to be suffered from heart failure due to mitral stenosis with atrial fibrillation, furosemide (20 mg per day) and digoxin (0.25 mg per day) was started. After digoxin had been raised to a dose of 0.50 mg per day because of sustained rapid ventricular response on the fourth hospital day, she complained of nausea and vomiting. Serum digoxin concentration was 2.55 ng/ml on the next day, and 1.08 ng/ml 96 hours after discontinuing digoxin. There was no complaint after digoxin was restarted with a dose of 0.05 mg per day. She complained of nausea again on the third day when the digoxin was raised to a dose of 0.083 mg in a blinded study. This observation indicates that digoxin intoxication could occur even in the smaller dose of digoxin than usual in the elderly.     

Coronary reserve of the hypertensive heart: relationship to left ventricular hypertrophy

We investigated the relationship between electrocardiographic left ventricular hypertrophy with ST-changes, and coronary circulation and myocardial metabolism in 25 patients with essential hypertension (systolic blood pressure greater than or equal to 160 mmHg, diastolic blood pressure greater than or equal to 95 mmHg). No patients had abnormal coronary arteriograms. They were categorized in two groups: non-hypertrophy group; cases with no hypertrophy on echocardiograms (interventricular septum and posterior wall thickness less than or equal to 11 mm), and hypertrophy group; cases with hypertrophy (wall thickness greater than or equal to 12 mm). Supine bicycle ergometry (50 watts, 50 rpm, 15 min) was performed during coronary sinus catheterization and electrocardiography. For cardiac hemodynamics, the coronary circulation and myocardial metabolism were observed at rest and during exercise. There was no significant difference in unit coronary blood flow (coronary blood flow per 100 gm) before exercise between the two groups. Unit coronary blood flow was significantly greater in the non-hypertrophy group after exercise. However, total coronary blood flow (coronary blood flow per 100 gm x left ventricular mass) showed no significant difference between the two groups. Coronary vascular resistance per 100 gm was higher in the hypertrophy group during exercise, though there was no significant difference at rest. Myocardial oxygen extraction O2 (A-C) was not different between the two groups at rest and during exercise, but unit myocardial oxygen consumption (MVO2) during exercise was higher in the non-hypertrophy group than in the hypertrophy group. The lactate extraction ratio tended to decrease in the hypertrophy group during exercise, and tended to increase in the non-hypertrophy group. Myocardial potassium flux tended to increase in the hypertrophy group during exercise.(ABSTRACT TRUNCATED AT 250 WORDS)     

The crystal structure of Boc-Pro-Val-Gly-NH2, with a remark on the conformation of the valyl residues in peptides

The crystal structure of Boc-Pro-Val-Gly-NH₂ has been determined: monoclinic; P2₁; a = 9.331 (3) Å, b = 9.532 (4), c = 23.080 (9), β= 91.33 (3)R, Z = 4; R = 0.053 for 3400 reflections with ˙Fo˙,>α(Fo). There are two independent but very similar molecules in the crystal. The peptide main chains are in an extended form, and packed in two kinds of antiparallel β sheets, the (φ, Φ) angles of the central Val residues are (-156°, 146°) and (-139°, 155°), and the mean length of the N- H . 0 hydrogen bonds in the sheets is 2.965 Å. A detailed study of the conformations of the Val residues in oligopeptide crystals shows that the preferred conformation of Val in peptides is: the (φ, Φ) angles close to those of the antiparallel β sheet, and C^γ1 and C^γ2, against N with respect to the C^α– C^β bond, at either (trans, gauche) or (-gauche, gauche). The mean π(NC^αC') angle of such Val residues is 107.9(9)°. A twisting in the β sheets is also discussed.     

Elevated plasma tissue factor antigen level in patients with disseminated intravascular coagulation

The plasma tissue factor (TF) antigen level was measured in patients with disseminated intravascular coagulation (DIC). The plasma TF antigen was detected In normal volunteers, and it was significantly higher in DIC patients than in non-DiC patients. However, in some patients with DiC, the plasma TF antigen level was within the normal range. The plasma TF antigen level in patients with DIC significantly decreased after therapy, but it was not correlated with organ failure or outcome. The plasma TF antigen level in patients with DIC was not correlated with other hemostatic markers. The plasma TF antigen level tended to be higher in DIC patients with nonlymphoid leukemia than in those with lymphoid tumor. TF might be implicated in the occurrence and progression of DIC. © 1994 Wiley-Liss, Inc.     

Effects of dietary salt on sodium-calcium exchange and ATP-driven calcium pump in arterial smooth muscle of Dahl rats.

AIM: To compare the effects of dietary salt on sodium-calcium exchange and the ATP-driven calcium pump in arterial smooth muscle between Dahl salt-sensitive (DS) and salt-resistant (DR) rats. METHODS: Aortic rings freshly excised from 16 DS rats and 16 DR rats on a low- (0.3%) or high- (8%) NaCl diet for 4 weeks were superfused with physiological saline and isometric tension was measured. In the presence of 10 mumol/l phentolamine, 10 mumol/l verapamil and 5 mmol/l caffeine, relaxation of a low-Na+ contraction was promoted by external calcium removal. RESULTS: On the high-salt diet, the rate of relaxation at 1.2 mmol/l extracellular sodium (calcium extrusion by calcium ATPase) was significantly lower in aortic rings from DS rats than from DR rats. The increase in the rates of relaxation from 1.2 mmol/l to normal (139.2 mmol/l) extracellular sodium (calcium extrusion by sodium-calcium exchange) was significantly greater with the high-salt diet than with the low-salt diet in rings from DR rats, but it was not different between the high- and low-salt diets in DS rats. The rate of increase in tonic tension by reducing extracellular Na+ from normal to 1.2 mmol/l in the presence of verapamil, caffeine and phentolamine (calcium entry by sodium-calcium exchange) was significantly lower in rings from DS rats than in those from DR rats on the high-salt diet. CONCLUSIONS: These observations suggest that the effects of dietary salt on the sodium-calcium exchange system in arterial smooth muscle differ between DS and DR rats and that calcium extrusion by the calcium pump is decreased in DS rats compared with DR rats. The lack of an increase in sodium-calcium exchange in salt-fed DS rats might lead to an elevation in cellular calcium and contribute to the mechanism of hypertension.