EFFICIENT STEREOSELECTIVE SYNTHESIS OF CATECHIN TRIMER DERIVATIVE USING SILVER LEWIS ACID-MEDIATED EQUIMOLAR CONDENSATION

A stereoselective synthesis of benzylated catechin trimer under intermolecular condensasion is achieved using equimolar amount of dimeric catechin nucleophile and monomeric catechin electrophile catalyzed by AgOTf or AgBF(4). The coupled product can be transformed into procyanidin C2 by a known procedure.ArticleHETEROCYCLES. 83(4):739-742 (2011)journal articl

Anti-inflammatory therapy by ibudilast, a phosphodiesterase inhibitor, in demyelination of twitcher, a genetic demyelination model

BACKGROUND: Twitcher mouse (twi/twi) is an authentic murine model of Krabbe's disease. Accumulation of psychosine, resulting in apoptosis of oligodendrocytes and subsequent demyelination, is a cardinal event to the pathogenesis of this disease. Moreover, recruitment of inflammatory cells plays a significant role in the pathological process in the twi/twi central and peripheral nervous systems. In this study, we investigated the 1) the relationship between tumor necrosis factor-α (TNFα), pro-inflammatory cytokine, and the progression of this disease and 2) effect of the anti-inflammatory therapy by ibudilast, a phosphodiesterase inhibitor. METHODS: We quantified the expression level of TNFα and TNF-receptor mRNA in twi/twi using semi-quantitative RT-PCR. The relationship between TNFα expression, apoptosis of oligodendrocytes and demyelination was studied with immunohistochemistry and TUNEL method. We then treated twi/twi with a daily intraperitoneal injection of ibudilast (10 mg/kg), which suppress TNFα production in the brain. RESULTS: We found that TNFα-immunoreactive microglia/macrophages appeared in the twi/twi brain and that the mRNA levels of TNFα and TNF-receptor 1 was increased with the progression of demyelination. The distribution profile of TNFα-immunoreactive microglia/macrophages overlapped that of TUNEL-positive oligodendrocytes in the twi/twi brain. When twi/twi was treated with ibudilast from PND30, the number of oligodendrocytes undergoing apoptosis was markedly reduced and demyelination was milder. Obvious improvement of clinical symptom was noted in two of five. The failure of constant clinical improvement by ibudilast may result from hepatotoxicity and/or the inhibition of proliferation of NG2-positive oligodendrocyte precursors. CONCLUSION: We conclude that anti-inflammatory therapy by a phosphodiesterase inhibitor can be considered as a novel alternative therapy for Krabbe's disease

Elimination of fukutin reveals cellular and molecular pathomechanisms in muscular dystrophy-associated heart failure

Heart failure is the major cause of death for muscular dystrophy patients, however, the molecular pathomechanism remains unknown. Here, we show the detailed molecular pathogenesis of muscular dystrophy-associated cardiomyopathy in mice lacking the fukutin gene (Fktn), the causative gene for Fukuyama muscular dystrophy. Although cardiac Fktn elimination markedly reduced alpha-dystroglycan glycosylation and dystrophin-glycoprotein complex proteins in sarcolemma at all developmental stages, cardiac dysfunction was observed only in later adulthood, suggesting that membrane fragility is not the sole etiology of cardiac dysfunction. During young adulthood, Fktn-deficient mice were vulnerable to pathological hypertrophic stress with downregulation of Akt and the MEF2-histone deacetylase axis. Acute Fktn elimination caused severe cardiac dysfunction and accelerated mortality with myocyte contractile dysfunction and disordered Golgi-microtubule networks, which were ameliorated with colchicine treatment. These data reveal fukutin is crucial for maintaining myocyte physiology to prevent heart failure, and thus, the results may lead to strategies for therapeutic intervention

AN EFFICIENT SYNTHESIS OF PROCYANIDINS USING EQUIMOLAR CONDENSATION OF CATECHIN AND/OR EPICATECHIN CATALYZED BY YTTERBIUM TRIFLATE

Stereoselective synthesis of catechin and epicatechin dimers under intermolecular condensation of equimolar amount of catechin derivatives catalyzed by Yb(OTf)(3). The coupled products were successfully converted to procyanidins B1, B2, B3, and B4, respectively. Procyanidins B1, B2, B3, and B4 could be used as standard compounds for identifying the polyphenols in natural source.ArticleHETEROCYCLES. 79:549-563 (2009)journal articl

Turtle spongious ventricles exhibit more compliant diastolic property and possess larger elastic regions of connectin in comparison to rat compact left ventricles

There is growing evidence that ventricular diastolic dysfunction is a major pathological factor in heart failure. Although many basic and clinical studies have been reported, there is little information available about the comparative and evolutionary aspects of the diastolic properties of vertebrate ventricles. Cardiac tissues in extant vertebrates are roughly divided into two types; compact myocardium in mammals and aves, and spongious myocardium in amphibians and some of reptilians. Here we compared the mechanical properties of both whole ventricles and the biochemical properties of isolated cardiomyocytes (including intracelluar Ca2+ ([Ca2+]i) handling, and the lengths of elastic regions of connectin, a protein that determines elasticity of cardiomyocytes) between spongious ventricles of turtles (Trachemys scripta elegans) and compact ventricles of Wister rats. Ventricular diastolic function is composed of active relaxation and passive compliance. We investigated ventricular compliance by analyzing normalized end-diastolic pressure-volume relationship (EDPVR) of diastolic-arrested ventricles to compare different-sized hearts and ventricular relaxation by determining logistic time constants of pressure decay. We measured [Ca2+]i handling using isolated cardiomyocytes. Stiffness constants obtained from exponential curve fitting were significantly larger in rat left ventricles (LVs) compared with turtle ventricles (99.0 ± 7.3 and 2.07 ± 0.62, respectively) showing that rat LVs were much stiffer than turtle ventricles. Normalization of EDPVRs revealed that the turtle ventricle and rat LV exhibit species-specific characteristics in ventricular compliance. At the cellular level, the initial normalized stiffness of rat cardiomyocytes (8.03 ± 1.33 kPa) was 2.8 times higher than in those of the turtle (2.82 ± 0.38 kPa), showing that turtle cardiomyocytes were much more compliant than those of rats. With respect to relaxation, the time constant of isovolumic relaxation in the rat LV pressuretime curve was significantly smaller than that in turtle ventricles (10.7 ± 0.96 and 67.4 ± 3.55 ms, respectively), resulting in early-phase-dominant ventricular filling patterns in rats. The time to peak [Ca2+]i and the decay time after peak [Ca2+]i in turtle cardiomyocytes were significantly longer than in rat. The numbers of amino acids of the PEVK domain of connectin, which is enriched in proline, glutamic acid, valine and lysine and encodes a random coil shown to be an important region in the passive elasticity of connectin were 821 and 204 in turtle and rat ventricles, respectively. These results suggest that vertebrate hearts have been becoming less compliant at the ventricle, cardiomyocyte, and molecular levels during the course of evolution. One possible physiological meaning of restricted compliance in rat ventricles could be related to a well-developed coronary circulation, because the less compliant mechanical properties of the ventricle are largely advantageous to preserve diastolic-dominant coronary arterial flow by preventing excessive ventricular expansion. Future research aimed at understanding the regulatory mechanisms of cardiac connectin among vertebrates may contribute to the investigation of the therapeutic potential of diastolic heart failure

TRPV2 is critical for the maintenance of cardiac structure and function in mice

The heart has a dynamic compensatory mechanism for haemodynamic stress. However, the molecular details of how mechanical forces are transduced in the heart are unclear. Here we show that the transient receptor potential, vanilloid family type 2 (TRPV2) cation channel is critical for the maintenance of cardiac structure and function. Within 4 days of eliminating TRPV2 from hearts of the adult mice, cardiac function declines severely, with disorganization of the intercalated discs that support mechanical coupling with neighbouring myocytes and myocardial conduction defects. After 9 days, cell shortening and Ca2+ handling by single myocytes are impaired in TRPV2-deficient hearts. TRPV2-deficient neonatal cardiomyocytes form no intercalated discs and show no extracellular Ca2+-dependent intracellular Ca2+ increase and insulin-like growth factor (IGF-1) secretion in response to stretch stimulation. We further demonstrate that IGF-1 receptor/PI3K/Akt pathway signalling is significantly downregulated in TRPV2-deficient hearts, and that IGF-1 administration partially prevents chamber dilation and impairment in cardiac pump function in these hearts. Our results improve our understanding of the molecular processes underlying the maintenance of cardiac structure and function

Perineuronal Oligodendrocytes Protect against Neuronal Apoptosis through the Production of Lipocalin-Type Prostaglandin D Synthase in a Genetic Demyelinating Model

The genetic demyelinating mouse "twitcher" is a model of the human globoid cell leukodystrophy, caused by galactosylceramidase (GALC) deficiency. Demyelination in the twitcher brain is secondary to apoptotic death of oligodendrocytes (OLs). Lipocalin-type prostaglandin (PG) D synthase (L-PGDS), a protein expressed in mature OLs, was progressively upregulated in twitcher OLs; whereas expression of OL-associated proteins such as carbonic anhydrase II, myelin basic protein, and myelin-associated glycoprotein was downregulated during demyelination in twitcher brains. The upregulation of L-PGDS was more remarkable in perineuronal OLs than in interfascicular OLs. A larger number of L-PGDS-positive OLs was found in selected fiber tracts of twitcher brains where fewer apoptotic cells were detected. The distribution of L-PGDS-positive OLs was inversely related to the severity of demyelination, as assessed by accumulation of scavenger macrophages. Mice doubly deficient for L-PGDS and GALC disclosed a large number of apoptotic neurons, which were never seen in twitcher brains, in addition to an increased number of apoptotic OLs. A linear positive correlation was observed between the population of L-PGDS-positive OLs in the twitcher brain and the ratio of apoptotic nuclei in the double mutant versus those in the twitcher, suggesting a dose-dependent effect of L-PGDS against apoptosis. These lines of evidence suggest that L-PGDS is an anti-apoptotic molecule protecting neurons and OLs from apoptosis in the twitcher mouse. This is a novel example of OL-neuronal interaction

Left ventricular mechanics and myocardial calcium dynamics in short-term and long-term hyperthyroid mice

The thyroid hormone is involved in cardiac adaptation to physiological and pathological stimuli. Although short-term hyperthyroidism enhances cardiac performance, longstanding hyperthyroidism can cause impairment of the contractility by pathological Ca2+ handling. Because the thyroid hormone affects cardiovascular hemodynamics by decreasing systemic arterial resistance and increasing circulating blood volume, it is important to accurately analyze left ventricular (LV) mechanics by using an index that is independent of ventricular loading conditions. Therefore, we adopted the end-systolic elastance (Ees), which is obtained by the linear regression of the end-systolic pressure-volume relationships. This reflects sensitive changes in the contractile state in a manner independent of both preload and afterload, providing an index of LV contractility. To better understand the hypertrophy caused by hyperthyroidism, we normalized the Ees according to LV weight for different sized heart. Hyperthyroidism was induced by a daily intraperitoneal injection of triiodothyronine (T3) at a dose of 2,000mg/kg body weight. Mice were divided into three groups: the synchronous control group, the T3 administration for one-week group (T3-short), and the T3 administration for eight-week group (T3-long). We investigated global LV mechanics, the expression of Na+/Ca2+ exchanger (NCX), the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA), and the Ca2+ handling of isolated cardiomyocytes in each group. Ees values in the control and T3-short were similar, and those in T3-long were significantly smaller than the control (256±60, 249±70 and 154±57mmHg・ml-1・gLV-1, respectively). The values of arterial elastance in both T3-short and T3-long, which represent afterload, were significantly smaller than the control. NCX expression was decreased in T3-short and declined in a time-dependent manner in T3-long. On the other hand, SERCA expression was rapidly elevated in T3-short and remained high in T3-long. These changes may be beneficial for cardiomyocytes in terms of O2 consumption for excitation-contraction coupling. In isolated cardiomyocyte experiments, cell shortening of T3-long mice was significantly lower than that of the control mice, but the average peak amplitude of Ca^ transients in T3-long was 79% and not significantly different. In conclusion, we evaluated LV contractility by using an Ees index in hyperthyroid mice. Although T3 administration shifted the Ca^ route in excitation-contraction coupling to the O_2-saving energetics, LV contractility was diminished with long-term T3 administration, showed constancy in peak amplitude of the Ca^ transients, and a decrease in NCX activity

Prostaglandin D2-Mediated Microglia/Astrocyte Interaction Enhances Astrogliosis and Demyelination in twitcher

Prostaglandin (PG)