Solid-Phase Synthesis of Phosphate/Boranophosphate Chimeric DNAs Using the H-Phosphonate-H-Boranophosphonate Method.

Boranophosphate (PB) DNAs are promising antisense oligonucleotide candidates because of their attractive features, such as high nuclease resistance and low toxicity. However, a full boranophosphate backbone modification to antisense DNAs causes reduced duplex formation with complementary RNAs and reduced antisense activity. In this study, an efficient solid-phase synthesis of phosphate/boranophosphate (PO/PB) chimeric DNA was achieved by the combination of the H-phosphonate and H-boranophosphonate methods. The physiological and biological properties of the synthesized PO/PB chimeric DNAs were also evaluated. The strategy employed herein can facilitate the design and synthesis of PO/PB chimeric DNAs containing site-specific boranophosphate modifications.

Sunitinib does not acutely alter left ventricular systolic function, but induces diastolic dysfunction.

PURPOSE: Cancer chemotherapies have improved the prognosis of cancer patients in recent years; however, their side effects on the cardiovascular systems have emerged as a major concern in the field of both cardiology and oncology. In particular, multi-targeted tyrosine kinase inhibitors are known to induce various types of cardiovascular adverse events including hypertension, QT-interval prolongation and heart failure, but their underlying mechanisms remain elusive. To explore how to better predict such drug-induced cardiovascular adverse events, we assessed the electropharmacological effects of sunitinib using the halothane-anesthetized dogs (n = 5), while plasma concentrations of cardiac enzymes including aspartate aminotransferase, lactate dehydrogenase, creatinine kinase and cardiac troponin I  were measured. METHODS: Sunitinib was intravenously administered at 0.01 and 0.1 mg/kg for 10 min with 20 min interval. RESULTS: Sunitinib decreased the amplitude of maximum downstroke velocity of the left ventricular pressure, prolonged the isovolumic relaxation time and increased the left ventricular end-diastolic pressure in a dose-related manner without affecting the other cardiohemodynamic and electrophysiological variables. More importantly, sunitinib significantly elevated cardiac troponin I level for 30-60 min after the high dose without altering the other biomarkers. CONCLUSIONS: Monitoring of the cardiac diastolic function together with cardiac troponin I after the start of sunitinib administration may become a reliable measure to predict the onset of sunitinib-induced cardiovascular adverse events.

Analysis of proarrhythmic potential of an atypical antipsychotic drug paliperidone in the halothane-anesthetized dogs.

Fatal cases with the use of atypical antipsychotic drug paliperidone have been reported; however, there was no clinical report describing paliperidone-induced torsade de pointes. In this study we assessed its electropharmacological effects together with its proarrhythmic potential in intravenous doses of 0.03, 0.3 and 3 mg/kg using the halothane-anesthetized dogs (n = 5), which could provide approximately 2, 20 and 200 times higher peak plasma drug concentrations than its therapeutic level, respectively. Paliperidone exerted potent vasodilator effect resulting in hypotension, which may be largely explained by its α1-adrenoceptor blocking action. In vivo electrophysiological results suggest that paliperidone may inhibit human ether-à-go-go-related gene K+ channel in a dose-related manner and modestly suppress Na+ channel in the in situ heart. The high dose of paliperidone may have some potential to induce early afterdepolarization that can trigger lethal ventricular arrhythmias, whereas the low and middle doses lack such proarrhythmic possibility, indicating that at least 20 times higher plasma concentration may be considered to be safe.

Pretreatment with and ongoing use of omega-3 fatty acid ethyl esters reduce the slow-flow phenomenon and prevent in-stent restenosis in patients undergoing carotid artery stenting.

OBJECTIVE: Carotid artery stenting (CAS) is a less invasive alternative to carotid endarterectomy, but it is essential to prevent thromboembolic complications during CAS and to suppress in-stent restenosis (ISR) after CAS because of the relatively high risk of periprocedural and follow-up stroke events. Clinical trials have demonstrated the strong relationship of carotid plaque vulnerability with the subsequent risk of ipsilateral ischemic stroke and thromboembolic complications during CAS. Recent studies demonstrated that both low eicosapentaenoic acid (EPA) and low docosahexaenoic acid (DHA) levels were significantly associated with lipid-rich coronary and carotid plaques, but little is known about the effect of administration of omega-3 fatty acids (O-3FAs) containing EPA and DHA before and after CAS for stabilizing carotid plaque, preventing thromboembolic complications, and suppressing ISR. In this study, the efficacy of pretreatment with and ongoing daily use of O-3FA in addition to statin treatment was evaluated in patients undergoing CAS. METHODS: This study was a nonrandomized prospective trial with retrospective analysis of historical control data. From 2012 to 2015, there were 100 consecutive patients with hyperlipidemia undergoing CAS for carotid artery stenosis who were divided into two groups. Between 2012 and 2013 (control period), 47 patients were treated with standard statin therapy. Between 2014 and 2015 (O-3FA period), patients were treated with statin therapy and add-on oral O-3FA ethyl esters containing 750 mg/d DHA and 1860 mg/d EPA from 4 weeks before CAS, followed by ongoing daily use for at least 12 months. In all patients, the plaque morphology by virtual histology intravascular ultrasound, the incidence of new ipsilateral ischemic lesions on the day after CAS, the slow-flow phenomenon during CAS, and ISR within 12 months after CAS were compared between the periods. RESULTS: The slow-flow phenomenon during CAS with filter-type embolic protection devices decreased in the O-3FA period (1 of 53 patients [2%]) compared with the control period (7 of 47 patients [15%]; P = .02). Furthermore, ISR for 12 months after CAS was significantly decreased in the O-3FA period (1 of 53 patients [2%]) compared with the control period (10 of 47 patients [21%]; P = .01). On virtual histology intravascular ultrasound analysis, the fibrofatty area was significantly smaller and the fibrous area was significantly greater in the O-3FA period. On multivariate logistic regression analysis, a low EPA/arachidonic acid ratio and a symptomatic lesion were the factors related to vulnerable plaque (P = .01 [odds ratio, 5.24; 95% confidence interval, 1.65-16.63] and P = .01 [odds ratio, 11.72; 95% confidence interval, 2.93-46.86], respectively). CONCLUSIONS: Pretreatment with O-3FA reduces the slow-flow phenomenon generated by plaque vulnerability during CAS, and on-going daily use of O-3FA suppresses ISR after CAS.

Assessment of the Anti-anginal Effect of Tetramethylpyrazine Using Vasopressin-Induced Angina Model Rats.

Intravenous tetramethylpyrazine has been widely used in China as a complementary and/or alternative medicine to treat patients with ischemic heart disease. We assessed the anti-anginal effect of tetramethylpyrazine (10 mg/kg, intravenously (i.v.), n=6) in comparison with that of its vehicle, saline (1 mL/kg, i.v., n=6), using vasopressin-induced angina model rats. First, Donryu rats were anesthetized with pentobarbital sodium (60 mg/kg, intraperitoneally (i.p.)), and the surface lead I electrocardiogram was continuously monitored. Administration of vasopressin (0.5 IU/kg, i.v.) to the rats depressed the S-wave level of the electrocardiogram, indicating the onset of subendocardial ischemia. However, pretreatment with tetramethylpyrazine suppressed the vasopressin-induced depression of the S-wave level, which was not observed following pretreatment with its vehicle alone (saline), suggesting that tetramethylpyrazine ameliorated the vasopressin-induced subendocardial ischemia in vivo. These results may provide experimental evidence for the empirically known clinical efficacy of tetramethylpyrazine against ischemic heart disease, and could provide clues to better understanding its in vivo mechanism of action.

Electropharmacological effects of amantadine on cardiovascular system assessed with J-Tpeak and Tpeak-Tend analysis in the halothane-anesthetized beagle dogs.

Since amantadine-induced long QT syndrome has been clinically reported, we investigated its electropharmacological effects to estimate the extent of proarrhythmic risk by using the halothane-anesthetized beagle dogs (n = 4). Amantadine in doses of 0.1, 1 and 10 mg/kg was infused over 10 min with a pause of 20 min under the monitoring of multiple cardiovascular variables. J-Tpeak and Tpeak-Tend were separately measured on the lead II electrocardiogram to precisely analyze the net balance between inward and outward current modifications by amantadine. The low dose increased the ventricular contractile force, but suppressed the intraventricular conduction. The middle dose prolonged the QT interval besides enhancing the changes induced by the low dose. The high dose increased the mean blood pressure, left ventricular end-diastolic pressure and total peripheral resistance, and accelerated the atrioventricular nodal conduction, but decreased the cardiac output besides enhancing the changes induced by the middle dose. A reverse use-dependence was confirmed in the repolarization delay. Amantadine hardly affected the J-Tpeak, but prolonged the Tpeak-Tend. Amantadine can be considered to stimulate Ca(2+) channel but inhibit Na(+) and K(+) channels in the in situ heart. J-Tpeak and Tpeak-Tend analysis suggests that amantadine may possess modest risk for arrhythmia.

Solid-phase synthesis of P-boronated oligonucleotides by the H-boranophosphonate method.

Recently, P-boronated oligonucleotides have been attracting much attention as potential therapeutic oligonucleotides. In this study, we developed H-boranophosphonate oligonucleotide bearing a borano group and hydrogen atom on the internucleotidic phosphorus and demonstrated that this novel P-boronated oligonucleotide is a versatile precursor to various P-boronated oligonucleotides such as boranophosphate, boranophosphorothioate, and boranophosphoramidate. The method was also applicable to the synthesis of a locked nucleic acid-modified boranophosphate oligonucleotide, which exhibited a dramatically enhanced affinity to complementary oligonucleotides.

Effects of Rikkunshito (traditional Japanese medicine) on enteral feeding and the plasma ghrelin level in critically ill patients: a pilot study.

BACKGROUND: Rikkunshito is a traditional Japanese medicine that has been widely prescribed for patients with various gastrointestinal symptoms. Recently, the prokinetic effects of Rikkunshito in patients with a variety of diseases have attracted attention in Japan. The prokinetic effects of Rikkunshito are believed to result from an increase of active ghrelin, which is most abundant in the stomach and which has a gastrokinetic function. The aim of the present pilot study was to investigate the effects of Rikkunshito on intragastric enteral feeding and plasma ghrelin levels in critically ill patients. METHODS: The study population consisted of critically ill patients who were projected to require intragastric tube feeding for more than 7 days. The patients were prospectively assigned to one of two treatment groups and were randomized to receive either Rikkunshito (2.5 g) or metoclopramide (10 mg) every 8 h. All patients received standard enteral nutrition. Patients in both groups were begun on intragastric tube feeding according to our institution's feeding protocol. RESULTS: All patients were undergoing mechanical ventilation at the time of enrollment. The portions of enteral nutrition provided to the target amount and the quantity of gastric discharge were not statistically significantly different between the two groups. The Rikkunshito group reached 50% of the target amount of enteral feeding significantly earlier than the metoclopramide group, although the proportion of patients in whom enteral feeding was successful did not differ significantly between the two groups. Patients in the Rikkunshito group showed significantly higher plasma levels of active ghrelin compared to those in the metoclopramide group. CONCLUSIONS: The administration of Rikkunshito increased the plasma level of active ghrelin, and induced prokinetic effects that were greater than those observed following treatment with metoclopramide in critically ill patients. TRIAL REGISTRATION: UMIN00000356.

Stereocontrolled solid-phase synthesis of phosphorothioate oligoribonucleotides using 2'-O-(2-cyanoethoxymethyl)-nucleoside 3'-O-oxazaphospholidine monomers.

A method for the synthesis of P-stereodefined phosphorothioate oligoribonucleotides (PS-ORNs) was developed. PS-ORNs of mixed sequence (up to 12mers) were successfully synthesized by this method with sufficient coupling efficiency (94-99%) and diastereoselectivity (≥98:2). The coupling efficiency was greatly improved by the use of 2-cyanoethoxymethyl (CEM) groups in place of the conventional TBS groups for the 2'-O-protection of nucleoside 3'-O-oxazaphospholidine monomers. The resultant diastereopure PS-ORNs allowed us to clearly demonstrate that an ORN containing an all-(Rp)-PS-backbone stabilizes its duplex with the complementary ORN, whereas its all-(Sp)-counterpart has a destabilizing effect.

Stereocontrolled synthesis of oligonucleotide analogs containing chiral internucleotidic phosphorus atoms.

Oligonucleotides, in which one of the two nonbridging oxygen atoms of internucleotidic phosphates is replaced by a different type of atom or a substituent, are useful as therapeutic agents and probes to elucidate mechanisms of enzymatic reactions. The internucleotidic phosphorus atoms of these oligonucleotides are chiral, and the properties of these oligonucleotides are affected by the absolute configuration of the chiral phosphorus atoms. In order to address the issue of chirality, various methods have been developed to synthesize these P-chiral oligonucleotide analogs in a stereocontrolled manner. This critical review focuses on the recent progress in this field (123 references).

Rapid glycosylations under extremely mild acidic conditions. Use of ammonium salts to activate glycosyl phosphites via P-protonation.

Trifluoromethanesulfonic acid salts of tertiary amines were employed as extremely mild acidic activators for rapid glycosylations. Glycosyl phosphite triesters bearing an acid-labile 4,4'-dimethoxytrityl (DMTr) group for transient protection worked as glycosyl donors effectively in the presence of the activators to afford the corresponding disaccharides in good yields without loss of the DMTr group.

Stereocontrolled synthesis of oligodeoxyribonucleoside boranophosphates via stereodefined H-phosphonate intermediates.

P-Stereodefined oligodeoxyribonucleoside boranophosphates (PB-ODNs) were successfully synthesized by the conversion of diastereopure H-phosphonate intermediates. Thermal denaturation studies clearly showed that the duplex stability of PB-ODNs with the complementary DNA and RNA depends on the stereochemistry of the boranophosphate linkages.

Solid-phase synthesis of stereoregular oligodeoxyribonucleoside phosphorothioates using bicyclic oxazaphospholidine derivatives as monomer units.

Nucleoside 3'-O-bicylic oxazaphospholidine derivatives were designed as monomer units for a solid-phase synthesis of stereoregular oligodeoxyribonucleoside phosphorothioates (PS-ODNs). The trans-isomers of appropriately designed nucleoside 3'-O-bicyclic oxazaphospholidine derivatives were generated exclusively by the reaction between the 3'-OH of the corresponding protected nucleosides and 2-chloro-1,3,2-oxazaphospholidine derivatives. The resultant trans-oxazaphospholidine isomers were configurationally stable, and their diastereopurity was not impaired by epimerization in the presence of an acidic activator during the condensation on a solid support. As a result, the formation of both (Rp)- and (Sp)-phosphorothioate internucleotide linkages by using the oxazaphospholidine monomers and the acidic activator proceeded without any loss of diastereopurity (diastereoselectivity > or = 99:1). In addition, ab initio molecular orbital calculations showed that the epimerization of oxazaphospholidine derivatives was most likely to proceed via an edge inversion process that was accelerated by N-protonation. The calculations rationalized not only the relations between the ring structure and the configurational stability of the oxazaphospholidines observed in this study but also the observations reported in the literature that the inversion of tricoordinated organophosphorus compounds were accelerated by acids or nucleophiles.

Solid-phase synthesis of oligodeoxyribonucleoside boranophosphates by the boranophosphotriester method.

Oligodeoxyribonucleoside boranophosphates (BH3-ODNs), containing four kinds of nucleobases, were synthesized by the solid-phase boranophosphotriester method. The 2'-deoxyribonucleoside 3'-boranophosphate monomers having 2-cyanoethyl (CE) groups as the phosphorus protecting groups were synthesized in good yields. A new condensing reagent, 1,3-dimethyl-2-(3-nitro-1,2,4-triazol-1-yl)-2-pyrrolidin-1-yl-1,3,2-diazaphospholidinium hexafluorophosphate, was found to be highly effective for the condensation reaction on the solid support. We also found that 1,8-bis(N,N-dimethylamino)naphthalene could accelerate the condensation reaction without causing beta-elimination of the CE groups from the boranophosphate triesters. The internucleotidic CE groups were selectively removed by treatment with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) under anhydrous conditions. The acetylation of the terminal 5'-hydroxy group was found to be effective to suppress the decomposition of the BH3-ODNs during the DBU treatment on the solid support. Under optimized conditions for the solid-phase synthesis and the deprotection reactions, BH3-ODNs (4mers and 12mers) containing four kinds of nucleobases were synthesized in good yields. The hybridization properties of the BH3-ODN 12mers with the complementary native DNAs and RNAs were determined by the thermal denaturing studies. In contrast to the low thermal melting (Tm) value of the duplex composed of T((PB)T)11 and native dA12 (12.8 degrees C), the duplex consisting of d(C(PB)A(PB)G(PB)T)3 and d(ACTG)3 showed a higher Tm value (44.7 degrees C) under high-salt conditions. Furthermore, d(C(PB)A(PB)G(PB)T)3 formed a more stable duplex with the complementary RNA, r(ACUG)3 with a Tm value of 50.5 degrees C. Thus, we first demonstrated that the binding affinity of BH3-ODN to a complementary DNA or RNA is dramatically increased, owing to the inclusion of the four kinds of nucleobases.