Masatoshi Koshiji

Inhibition by berberine of cyclooxygenase-2 transcriptional activity in human colon cancer cells.

The enzyme cyclooxygenase-2 (COX-2) is abundantly expressed in colon cancer cells and plays a key role in colon tumorigenesis. Compounds inhibiting COX-2 transcriptional activity have therefore potentially a chemopreventive property against colon tumor formation. An assay method for estimating COX-2 transcriptional activity in human colon cancer cells was established using a beta-galactosidase reporter gene system, and examination was made of various medicinal herbs and their ingredients for an inhibitory effect on COX-2 transcriptional activity. We found that berberine, an isoquinoline alkaloid present in plants of the genera Berberis and Coptis, effectively inhibits COX-2 transcriptional activity in colon cancer cells in a dose- and time-dependent manner at concentrations higher than 0.3 microM. The present findings may further explain the mechanism of anti-inflammatory and anti-tumor promoting effects of berberine.

Expression of Atrial and Brain Natriuretic Peptides and Their Genes in Hearts of Patients With Cardiac Amyloidosis

OBJECTIVES We investigated the expression of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) and their genes in the hearts of patients with cardiac amyloidosis and those with isolated atrial amyloidosis. BACKGROUND The expression of ANP and BNP is augmented in the ventricles of failing or hypertrophied hearts, or both. The expression of ANP and BNP in the ventricles of hearts with cardiac amyloidosis, which is hemodynamically similar to restrictive cardiomyopathy, is not yet known. ANP is the precursor protein of isolated atrial amyloid. METHODS We analyzed the immunohistocytochemical localizations of ANP and BNP as well as the expression of their mRNAs by in situ hybridization in the myocardium and measured the plasma levels of ANP and BNP in patients with cardiac amyloidosis. RESULTS Four of the five right and all six left ventricular endomyocardial biopsy specimens obtained from six patients with cardiac amyloidosis were immunohistochemically positive for both ANP and BNP; none of the biopsy specimens from eight normal subjects were positive for ANP or BNP. All four of the right atria obtained at operation showed positive immunoreactions for both peptides. Electron microscopy identified specific secretory granules in ventricular myocytes of the patients with cardiac amyloidosis, but not in ventricular myocytes from the normal control subjects. Double immunocytochemical analysis revealed the co-localization of ANP and BNP in the same granules and that isolated atrial amyloid fibrils were immunoreactive for ANP and BNP, whereas ventricular amyloid fibrils were negative for both peptides. Both ANP mRNA and BNP mRNA were expressed in the ventricles of the patients with cardiac amyloidosis but not in the normal ventricles. The autopsy study of four patients with cardiac amyloidosis revealed an almost transmural distribution of ANP and BNP, with predominance in the endocardial side. Plasma BNP levels in the patients were markedly elevated ([mean +/- SD] 1,165.1+/-561.2 pg/ml) compared with those in the control subjects (8.9+/-6.0 pg/ml, p < 0.05). CONCLUSIONS Expression of ANP and BNP and their genes was augmented in the ventricular myocytes of the patients with cardiac amyloidosis. Both regional mechanical stress by amyloid deposits and hemodynamic stress by diastolic dysfunction may be responsible for the expression of the peptides in patients with cardiac amyloidosis.

Endothelin-1 and Its Receptor in Hypertrophic Cardiomyopathy

Endothelin-1, a potent vasoconstrictor produced by vascular endothelial cells, activates the hypertrophic program in cultured heart muscle cells. However, the role of endothelin-1 in cardiac hypertrophy in humans is unknown. Therefore, we studied hypertrophic cardiomyopathy patients with normal pulmonary arterial pressure, in whom cardiac hypertrophy is a specific feature of the disease. Radioimmunoassay with a monoclonal antibody to human endothelin-1 showed that the plasma level of immunoreactive endothelin was more than twofold higher in hypertrophic cardiomyopathy patients than in control subjects (P < .005). In situ hybridization analysis of endomyocardial biopsy specimens showed positive signals of endothelin-1 type A receptor mRNA in ventricular myocytes of all specimens. The receptor expression in ventricular myocytes was similar between hypertrophic cardiomyopathy patients and control subjects. We propose that endothelin-1 might represent an important factor involved in hypertrophic cardiomyopathy. Whether endothelin-1 plays a causal role in cardiac hypertrophy or is a marker of its occurrence needs to be clarified.

Infarct size-reducing effect of ischemic preconditioning is related to α1b-adrenoceptors but not to α1a-adrenoceptors in rabbits

Summary:In rabbits and rats, both stimulation of α1-adrenoceptors and ischemic preconditioning (PC) reduce infarct size. Activation of α1b-adrenoceptors play an important role in the PC effect on ventricular function in rats. However, the α1-adrenoceptors have not been reported to be related to the

Modulation of noradrenaline release through presynaptic α2-adrenoceptors in congestive heart failure

Stimulation of presynaptic alpha 2-adrenoceptors inhibits the release of noradrenaline from sympathetic nerve endings; however, the extent to which it operates in patients with congestive heart failure is still unknown. To investigate the degree of negative feedback to the release of noradrenaline via presynaptic alpha 2-adrenoceptors at sympathetic nerve endings, we measured plasma noradrenaline levels before and after the injection of phentolamine (i.e., plasma noradrenaline concentration at rest, plasma noradrenaline concentration after phentolamine injection [NAph], and the phentolamine-induced increase in plasma noradrenaline [delta NAph]). Plasma noradrenaline concentration at rest, NAph, and delta NAph increased in a stepwise manner from New York Heart Association class I to class III. A positive correlation was found between the plasma noradrenaline at rest and delta Naph (n = 123, r = 0.697, p < 0.001). These results suggest that the enhanced release of plasma noradrenaline is substantially buffered by the mechanism of noradrenaline release-inhibitory presynaptic alpha 2-adrenoceptors in patients with congestive heart failure, and this buffer serves to protect organs such as the heart from excess sympathetic stimulation.

Gallic acid induces vascular smooth muscle cell death via hydroxyl radical production

Abstract In the present study, we investigated whether gallic acid (GA) can induce death in cultured vascular smooth muscle cells (VSMCs), and whether production of the hydroxyl radical (·OH) is involved in the process of GA action. GA killed cultured VSMCs from rat aorta, in a dose- and time-dependent manner. Cytoplasmic shrinkage and nuclear condensation were observed light microscopically in GA-treated VSMCs, which appeared apoptotic. However, the ultrastructure of the VSMC was not typical of apoptosis: nuclear condensation was not glossy, and the plasma membrane and subcellular organelles were disrupted. Although the VSMC were positive for in situ nick end-labeling (TUNEL), they did not show a DNA ladder pattern on gel electrophoresis and were negative for Taq polymerase-based in situ ligation, which is more specific for apoptosis than TUNEL. Moreover, GA-induced cell death was not prevented by Boc-Asp-fmk (a pan-caspase inhibitor). Production of ·OH was detected in GA-treated VSMCs using high-performance liquid chromatography with salicylic acid as a trapping agent. Lipid peroxidation was also observed. The production of ·OH was inhibited by catalase (CAT) and deferoxamine (DFX), and these treatments completely rescued VSMCs from cell death. In a cell-free system, GA produced ·OH in the presence of Fe2+-EDTA, which was quenched by CAT and DFX, suggesting involvement of the Haber–Weiss reaction. Oxidative stress by reactive oxygen species, ·OH in particular, is one of the mechanisms of GA-induced death of VSMCs, the mode of which was different from typical apoptosis.

LOSARTAN AND CAPTOPRIL FOLLOW DIFFERENT MECHANISMS TO DECREASE PRESSOR RESPONSES IN THE PITHED RAT

1. We investigated the effects of losartan and captopril on noradrenaline (NA) release and vascular reactivity to NA in the pithed rat.

Enalapril decreases plasma noradrenaline levels during the cold pressor test in human hypertensives.

1. The effects of the angiotensin‐converting enzyme (ACE) inhibitor enalapril on the responses of blood pressure and plasma catecholamine levels to the cold pressor test in human hypertensives were examined.

Effects of adrenaline infusion on plasma lipids and noradrenaline levels in rabbits with adriamycin-induced cardiomyopathy.

1. We investigated the acute effects of adrenaline infusion on plasma lipid levels in vehicle‐ and adriamycin‐treated rabbits. Lipids were measured before and 30 and 60 min after the commencement of continuous intravenous administration of adrenaline (0.06 |xg/kg per min) or saline in pentobarbital‐anaesthetized rabbits.

Simultaneous evaluation of left- and right-sided heart pumping function during dynamic leg exercise in patients with mild chronic congestive heart failure, with special reference to afterload and plasma noradrenaline

SummaryWe simultaneously measured increases in mean pulmonary capillary wedge pressure (ΔPCW), mean right atrial pressure (ΔRA), and cardiac index (ΔCI) in response to dynamic leg exercise in 81 patients with mild congestive heart failure to clarify the relationship between the left-sided and right-sided pumping function of the heart. The ratio of ΔCI to ΔPCW was used as an index of left-sided heart performance and the ΔCI/ΔRA as an index of right-sided heart performance. We also determined systemic vascular resistance, as an index of afterload on the left heart; pulmonary vascular resistance, as an index of afterload on the right heart; and the plasma level of noradrenaline before and during dynamic leg exercise. Patients with ΔCI/ΔPCW > 0.18l/min/m2 per mmHg were regarded as having a well functioning left heart, and the patients with ΔCI/ΔPCW ≤ 0.18l/min/m2 per mmHg as having a poorly functioning left heart. Patients with ΔCI/ΔRA > 0.311l/min/m2 per mmHg were regarded as having a well functioning right heart, and those with ΔCI/ΔRA ≤ 0.311/l/min/m2 per mmHg as having a poorly functioning right heart. Patients were classified into three groups: well functioning left and right heart (normal group;n = 40), poorly functioning left and right heart (bilateral group;n = 34), and poorly functioning left heart and well functioning right heart (left-sided group;n = 7). The systemic vascular resistance index decreased during leg exercise in all patients. The decrease was smaller in the bilateral group and the left-sided group than in the normal group. The pulmonary vascular resistance index increased during exercise in the bilateral group but was unchanged in the normal group and the left-sided group. The plasma level of noradrenaline increased during exercise in all patients, but the increase was greater in the bilateral and left-sided groups than in the normal group. Pretreatment with phentolamine, an α-adrenoceptor antagonist, inhibited the increase in the pulmonary vascular resistance index and restored the decrease in the systemic vascular resistance index during exercise in the bilateral group. Our results showed that systemic vascular resistance, which represents afterload on the left heart, increased in the presence of impaired left-sided heart pumping function and pulmonary vascular resistance, which represents afterload on the right heart, increased in the presence of impaired right-sided heart pumping function. The inhibited decrease in systemic vascular resistance and the increase in pulmonary vascular resistance during exercise were associated with α-adrenoceptor-mediated vasoconstriction caused by the increase in the plasma level of noradrenaline.