An efficient and novel method for synthesizing 3′,5′-dithio-2′-deoxyguanosine was described.In this method normal guanosine was used as the starting material.A very efficient procedure was used to synthesize 2-O-to...An efficient and novel method for synthesizing 3′,5′-dithio-2′-deoxyguanosine was described.In this method normal guanosine was used as the starting material.A very efficient procedure was used to synthesize 2-O-tosylguanosine 1,which used 0.1 eq.DBTO instead of 2 eq.1 was treated with LTBH to give 9-(2-deoxy-β-D-threo-pentofuranosyl)guanine 2.2 could be easily turned to the target compound.展开更多
AIM To investigate the potential effect of inhibitors of phosphodiesterase-5(PDE-5) for therapy of portal hypertension in liver cirrhosis.METHODS In the rat model of thioacetamide-induced liver fibrosis/cirrhosis the ...AIM To investigate the potential effect of inhibitors of phosphodiesterase-5(PDE-5) for therapy of portal hypertension in liver cirrhosis.METHODS In the rat model of thioacetamide-induced liver fibrosis/cirrhosis the nitric oxide-cyclic guanosine monophosphate(NO-cGMP) pathway was investigated. Expression and localization of PDE-5, the enzyme that converts vasodilating cGMP into inactive 5'-GMP, was in the focus of the study. Hepatic gene expression of key components of the NO-cGMP pathway was determined by qRT-PCR: Endothelial NO synthase(eNOS), inducible NO synthase(iNOS), soluble guanylate cyclase subunits α1 and β1(sGCa1, sGCb1), and PDE-5. Hepatic PDE-5 protein expression and localization were detected by immunohistochemistry. Serum cGMP concentrations were measured using ELISA. Acute effects of the PDE-5 inhibitor Sildenafil(0.1 mg/kg or 1.0 mg/kg) on portal and systemic hemodynamics were investigated using pressure transducers.RESULTS Hepatic gene expression of eNOS(2.2-fold; P = 0.003), sGCa1(1.7-fold; P = 0.003), sGCb1(3.0-fold; P = 0.003), and PDE-5(11-fold; P = 0.003) was increased in cirrhotic livers compared to healthy livers. Overexpression of PDE-5(7.7-fold; P = 0.006) was less pronounced in fibrotic livers. iNOS expression was only detected in fibrotic and cirrhotic livers. In healthy liver, PDE-5 protein was localized primarily in zone 3 hepatocytes and to a lesser extent in perisinusoidal cells. This zonation was disturbed in cirrhosis: PDE-5 protein expression in perisinusoidal cells was induced approximately 8-fold. In addition, PDE-5-expressing cells were also found in fibrous septa. Serum cGMP concentrations were reduced in rats with cirrhotic livers by approximately 40%. Inhibition of PDE-5 by Sildenafil caused a significant increase in serum cGMP concentrations [+ 64% in healthy rats(P = 0.024), + 85% in cirrhotic rats(P = 0.018)]. Concomitantly, the portal venous pressure was reduced by 19% in rats with liver cirrhosis. CONCLUSION Overexpression and abrogated zonation of PDE-5 likely contribute to the pathogenesis of cirrhotic portal hypertension. PDE-5 inhibition may therefore be a reasonable therapeutic approach for portal hypertension.展开更多
Purines have a recognized importance as intercellular messengers.These molecules play an important role in the development and maintenance of the central nervous system(CNS),as well as in its response to pathological ...Purines have a recognized importance as intercellular messengers.These molecules play an important role in the development and maintenance of the central nervous system(CNS),as well as in its response to pathological conditions.Both adenine and guanine-based purines can be released from astrocytes,where they play a relevant role as extracellular signaling molecules.Particularly,the nucleoside guanosine has been proposed as an extracellular molecule展开更多
Background:This study aims to investigate the therapeutic effect of Wa medicine Niang-Mu-Liang medicinal liquor(NML)on rats with diabetes mellitus erectile dysfunction(DMED)and its impact on the ferroptosis signaling ...Background:This study aims to investigate the therapeutic effect of Wa medicine Niang-Mu-Liang medicinal liquor(NML)on rats with diabetes mellitus erectile dysfunction(DMED)and its impact on the ferroptosis signaling pathway.Methods:Thirty Sprague-Dawley rats were randomly divided into three groups:Control,DMED,and NML.After establishing the DMED model,treatments were administered for 8 weeks.After the administration,apomorphine hydrochloride tests were conducted to measure the mass and organ index of testes and epididymides,sperm concentration and viability in each group.Penile corpus cavernosum tissues were stained with hematoxylin and eosin.Nitric oxide and cyclic guanosine monophosphate levels in the penile corpus cavernosum tissues were determined using biochemical kits and enzyme-linked immunosorbent assay,while the expression of proteins related to the ferroptosis signaling pathway was measured by Western blot.Results:Compared to the DMED group,the DMED rats treated with NML showed significantly increased erection frequency,testicular and epididymal mass and index,sperm count and viability,along with noticeable improvement in the pathological morphology of penile corpus cavernosum.The content of nitric oxide and cyclic guanosine monophosphate,and the expression of ferritin heavy chain,ferritin light chain,and glutathione peroxidase 4 proteins in penile corpus cavernosum tissue were elevated,while the expression of transferrin and STEAP3 proteins was reduced.Conclusion:NML can improve erectile function in DMED rats by inhibiting the ferroptosis signaling pathway.展开更多
Nucleotide-specific fluorescence quenching in fluorescently labeled DNA has many applications in biotechnology. We have studied the inter-and intra-molecular quenching of tetramethylrhodamine (TMR) by nucleotides to b...Nucleotide-specific fluorescence quenching in fluorescently labeled DNA has many applications in biotechnology. We have studied the inter-and intra-molecular quenching of tetramethylrhodamine (TMR) by nucleotides to better understand their quenching mechanism and influencing factors. In agreement with previous work, dGMP can effectively quench TMR, while the quenching of TMR by other nucleotides is negligible. The Stern-Volmer plot between TMR and dGMP delivers a bimolecular quenching constant of Ks=52.3 M-1. The fluorescence of TMR in labeled oligonucleotides decreases efficiently through photoinduced electron transfer by guanosine. The quenching rate constant between TMR and guanosine was measured using fluorescence correlation spectroscopy (FCS). In addition, our data show that the steric hindrance by bases around guanosine has significant effect on the G-quenching. The availability of these data should be useful in designing fluorescent oligonucleotides and understanding the G-quenching process.展开更多
The study on the interaction of cisplatin with guanosine in neutral solution by 13C NMR spectroscopy has shown that besides the formation of [Pt（NH3）2（N7-Guo）2]2+, a new 1:1 complex [Pt（NH3）2(N7.N1-GuoH-1)]nn+, ...The study on the interaction of cisplatin with guanosine in neutral solution by 13C NMR spectroscopy has shown that besides the formation of [Pt（NH3）2（N7-Guo）2]2+, a new 1:1 complex [Pt（NH3）2(N7.N1-GuoH-1)]nn+, in which deprotonated guanosine was bonded to platium by N1 and N7 atoms, was also formed. Recently we have succeed-展开更多
Deamination is a crucial step in the transformation of 6-cyclopropylamino guanosine prodrug to its active form. A convenient method using capillary electrophoresis(CE) without sample labeling was developed to analyze ...Deamination is a crucial step in the transformation of 6-cyclopropylamino guanosine prodrug to its active form. A convenient method using capillary electrophoresis(CE) without sample labeling was developed to analyze the deamination of a series of D-/L-6-cyclopropylamino guanosine analogs by mouse liver homogenate, mouse liver microsome, and adenosine deaminase(ADA). A two-step process involving a 6-amino guanosine intermediate formed by oxidative N-dealkylation was demonstrated in the metabolism of 6-cyclopropylamino guanosine to 6-hydroxy guanosine. The results indicated that the transformation rates of different prodrugs to the active form varied greatly, which were closely correlated with the configuration of nucleosides and the structure of glycosyl groups. Most importantly,D-form analogs were metabolized much faster than their L-counterparts, thus clearly pointed out that compared to guanine, modification of glycosyl part might be a better choice for the development of L-guanosine analogs for the treatment of HIV.展开更多
While 8-oxo-7,8-dihydro-2′-deoxyguanosine(dOG)on DNA G-quadruplex(G4)has been studied,the influence of 8-oxo-7,8-dihydro-guanosine(rOG)lesions on telomeric repeat-containing RNA(TERRA)G4 deserves an in-depth study.Th...While 8-oxo-7,8-dihydro-2′-deoxyguanosine(dOG)on DNA G-quadruplex(G4)has been studied,the influence of 8-oxo-7,8-dihydro-guanosine(rOG)lesions on telomeric repeat-containing RNA(TERRA)G4 deserves an in-depth study.The single-strand and guanine-rich characters of TERRA make it vulnerable to form rOG lesions.Our current study demonstrated that rOG located in the internal layer and external layer of TERRA impacted the G4 stability in different ways and perturbed RNA replication,as well as base-pair strength and stability.展开更多
Objective:To investigate the effect of epigallocatechin-3-gallate(EGCG)on endothelial dysfunction in spontaneously hypertensive rats(SHR).Methods:Wistar-Kyoto(WKY)rats and SHR were divided into four groups;WKY control...Objective:To investigate the effect of epigallocatechin-3-gallate(EGCG)on endothelial dysfunction in spontaneously hypertensive rats(SHR).Methods:Wistar-Kyoto(WKY)rats and SHR were divided into four groups;WKY control,SHR control and SHR treated with EGCG(50 mg/kg/day)or losartan(10 mg/kg/day).The treatment was given daily for 4 weeks by oral gavage and the blood pressure was monitored by tail-cuff method every 3 days.Acetylcholineinduced endothelium-dependent relaxations were assessed in isolated phenylephrine-precontracted aortic rings at the end of treatment.The vascular levels of reactive oxygen species,nitric oxide,tetrahydrobiopterin,and cyclic guanosine monophosphate were also measured.Moreover,the expression of angiotensinⅡtype 1(AT_(1))receptor protein was determined.Results:The systolic blood pressure was significantly decreased in SHR treated with EGCG.The impaired endothelium-dependent relaxation was significantly improved in aortic ring isolated from the EGCG-treated SHR group.EGCG also significantly increased the levels of nitric oxide,tetrahydrobiopterin,and cyclic guanosine monophosphate,while decreasing the level of reactive oxygen species and the protein expression of AT_(1)receptor in SHR.Conclusions:EGCG attenuates endothelial dysfunction in SHR by decreasing oxidative stress and increasing vascular nitric oxide bioavailability,which may be modulated partly by inhibition of vascular AT_(1)receptors.An increase in endothelium-dependent relaxation may contribute to a decrease in blood pressure in hypertensive animals.展开更多
AIM To investigate the effects of plecanatide and dolcanatide on maintenance of paracellular permeability, integrity of tight junctions and on suppression of visceral hypersensitivity. METHODS Transport of fluorescein...AIM To investigate the effects of plecanatide and dolcanatide on maintenance of paracellular permeability, integrity of tight junctions and on suppression of visceral hypersensitivity. METHODS Transport of fluorescein isothiocyanate(FITC)-dextran was measured to assess permeability across cell monolayers and rat colon tissues. Effects of plecanatide and dolcanatide on the integrity of tight junctions in Caco-2 and T84 monolayers and on the expression and localization of occludin and zonula occludens-1(ZO-1) were examined by immunofluorescence microscopy. Anti-nociceptive activity of these agonists was evaluated in trinitrobenzene sulfonic acid(TNBS)-induced inflammatory as well as in non-inflammatory partial restraint stress(PRS) rat models. Statistical significance between the treatment groups in the permeability studies were evaluated using unpaired t-tests.RESULTS Treatment of T84 and Caco-2 monolayers with lipopolysaccharide(LPS) rapidly increased permeability, which was effectively suppressed when monolayers were also treated with plecanatide or dolcanatide. Similarly, when T84 and Caco-2 monolayers were treated with LPS, cell surface localization of tight junction proteins occludin and ZO-1 was severely disrupted. When cell monolayers were treated with LPS in the presence of plecanatide or dolcanatide, occludin and ZO-1 were localized at the cell surface of adjoining cells, similar to that observed for vehicle treated cells. Treatment of cell monolayers with plecanatide or dolcanatide without LPS did not alter permeability, integrity of tight junctions and cell surface localization of either of the tight junction proteins. In rat visceral hypersensitivity models, both agonists suppressed the TNBS-induced increase in abdominal contractions in response to colorectal distension without affecting the colonic wall elasticity, and both agonists also reduced colonic hypersensitivity in the PRS model. CONCLUSION Our results suggest that activation of GC-C signaling might be involved in maintenance of barrier function, possibly through regulating normal localization of tight junction proteins. Consistent with these findings, plecanatide and dolcanatide showed potent antinociceptive activity in rat visceral hypersensitivity models. These results imply that activation of GC-C signaling may be an attractive therapeutic approach to treat functional constipation disorders and inflammatory gastrointestinal conditions.展开更多
BACKGROUND Changes in N-linked glycosylation have been observed in the circulation of individuals with hepatocellular carcinoma. In particular, an elevation in the level of core fucosylation has been observed. However...BACKGROUND Changes in N-linked glycosylation have been observed in the circulation of individuals with hepatocellular carcinoma. In particular, an elevation in the level of core fucosylation has been observed. However, the mechanisms through which core fucose is increased are not well understood. We hypothesized that a review of the literature and related bioinformatic review regarding six genes known to be involved in the attachment of core fucosylation, the synthesis of the fucosylation substrate guanosine diphosphate(GDP)-fucose, or the transport of the substrate into the Golgi might offer mechanistic insight into the regulation of core fucose levels.AIM To survey the literature to capture the involvement of genes regulating core Nlinked fucosylation in hepatocellular carcinoma METHODS The PubMed biomedical literature database was searched for the association of hepatocellular carcinoma and each of the core fucose-related genes and their protein products. We also queried The Cancer Genome Atlas Liver hepatocellular carcinoma(LIHC) dataset for genetic, epigenetic and gene expression changes for the set of six genes using the tools at cBioportal.RESULTS A total of 27 citations involving one or more of the core fucosylation-related genes(FPGT, FUK, FUT8, GMDS, SLC35 C1, TSTA3) and hepatocellular carcinoma were identified. The same set of gene symbols was used to query the371 patients with liver cancer in the LIHC dataset to identify the frequency of m RNA over or under expression, as well as non-synonymous mutations, copy number variation and methylation level. Although all six genes trended to moresamples displaying over expression relative to under-expression, it was noted that a number of tumor samples had undergone amplification of the genes of the de novo synthesis pathway, GMDS(27 samples) and TSTA3(78 samples). In contrast, the other four genes had undergone amplification in 2 or fewer samples.CONCLUSION Amplification of genes involved in the de novo pathway for generation of GDPfucose, GMDS and TSTA3, likely contributes to the elevated core fucose observed in hepatocellular carcinoma.展开更多
Colorectal cancer(CRC) is a major cause of cancerrelated mortality and morbidity worldwide. While improved treatments have enhanced overall patient outcome, disease burden encompassing quality of life, cost of care, a...Colorectal cancer(CRC) is a major cause of cancerrelated mortality and morbidity worldwide. While improved treatments have enhanced overall patient outcome, disease burden encompassing quality of life, cost of care, and patient survival has seen little benefit. Consequently, additional advances in CRC treatments remain important, with an emphasis on preventative measures. Guanylyl cyclase C(GUCY2C), a transmembrane receptor expressed on intestinal epithelial cells, plays an important role in orchestrating intestinal homeostatic mechanisms. These effects are mediated by the endogenous hormones guanylin(GUCA2A) and uroguanylin(GUCA2B), which bind and activate GUCY2 C to regulate proliferation, metabolism and barrier function in intestine. Recent studies have demonstrated a link between GUCY2 C silencing and intestinal dysfunction, including tumorigenesis. Indeed, GUCY2 C silencing by the near universal loss of its paracrine hormone ligands increases colon cancer susceptibility in animals and humans. GUCY2C's role as a tumor suppressor has opened the door to a new paradigm for CRC prevention by hormone replacement therapy using synthetic hormone analogs, such as the FDA-approved oral GUCY2 C ligand linaclotide(Linzess^(TM)). Here we review the known contributions of the GUCY2 C signaling axis to CRC, and relate them to a novel clinical strategy targeting tumor chemoprevention.展开更多
The aim of the current study was to investigate the pharmacological activity of glabridinon the isolated human saphenous vein (SV) and explore the underlying mechanisms. Samples of patients' SVs were removed durin...The aim of the current study was to investigate the pharmacological activity of glabridinon the isolated human saphenous vein (SV) and explore the underlying mechanisms. Samples of patients' SVs were removed during bypass surgery, and 4-mm lengths of the vessels were placedin Krebs solution at ±4℃ and hung in an isolated organ bath to assess their contraction/relaxationresponses. The contraction/relaxation responses were recorded to observe if the cyclic guanosinemonophosphate (cGMP)/protein kinase G (PKG) pathway mediates the relaxant effect of glabridinafter treatment with blockers like ODQ (a guanylate cyclase inhibitor), KT5823 (a PKG inhibitor),isobutylmethylxanthine [IBMX, a phosphodiesterase (PDE) inhibitor], and cantharidin [Cant,a myosin light-chain phosphatase (MLCP) inhibitor]. Moreover, nitric oxide (NO), cGMP, andPKG levels in SV tissues were determined by ELISA after incubation with glabridin, N(o)-nitro-L-arginine methyl ester (L-Name, a NO synthetase inhibitor), phenylephrine (PE), ODQ, IBMX,and KT5823. The results showed that glabridin relaxed the vascular smooth muscle of humanSV pretreated with PE in a dose-dependent manner, which was independent of the endothelium.The vasorelaxant effect of glabridin was only inhibited by iberiotoxin (IbTX), Cant, and KT5823.Glabridin increased cGMP and PKG levels in SV homogenates, whereas it did not alter the NOlevel. The enhancing efects of cGMP and PKG levels by glabridin were abolished by ODQ andKT5823. In conclusion, glabridin has a vasorelaxant effect, which is associated with the activationof BKc. channels and inhibition of PDE.展开更多
Carcinogenesis is associated with malfunction in the cGMP-mediated regulation of cytosolic Ca<sup>2+</sup> and reactive oxygen species. Chemotherapy resistant cancer cells are re-sensitised to apoptosis by...Carcinogenesis is associated with malfunction in the cGMP-mediated regulation of cytosolic Ca<sup>2+</sup> and reactive oxygen species. Chemotherapy resistant cancer cells are re-sensitised to apoptosis by the action of a substantial number of natural compounds on cell membrane multidrug resistant proteins. Chemical structures of pro-apoptotic and anti-apoptotic compounds demonstrate relative molecular similarity to cGMP. This study uses a computational chemistry program to investigate molecular similarity within cGMP and chemo-preventative structures. Chemotherapeutic drugs and resistance modulators provide multiple fits to a nucleotide template that differ in their relationship to the cyclised ring of cGMP. The alternative fits of drug and modulator structures may relate to the development and unblocking of apoptosis and drug resistance.展开更多
Common abbreviations,acronyms and short names are listed below.These shortened forms,and otherabbreviations not in this list,should always be defined at first usage in both abstract and text.Some of themare well-known...Common abbreviations,acronyms and short names are listed below.These shortened forms,and otherabbreviations not in this list,should always be defined at first usage in both abstract and text.Some of themare well-known and can be used directly without confusion.展开更多
Objective: To explore the role of nitric oxide (NO), an internal vasodilative factor, in occurrence ofpregnancy induced hypertension (PIH). Methods: The antepartum and postpartum levels of NO2-/NO3-, the stable metabo...Objective: To explore the role of nitric oxide (NO), an internal vasodilative factor, in occurrence ofpregnancy induced hypertension (PIH). Methods: The antepartum and postpartum levels of NO2-/NO3-, the stable metabolic end product of NO, and those of cyclic guanosine monophosphate (cGMP) in 30 patients with PIHand 30 healthy women in their late pregnancy were measured with greiss reagent. ResultS: ① The plasma levels ofNO2-/NO3- and cGMP were significantly decreased in patients with PIH as compared with the healthy women (P<0. 05). ②In patients with PlH, the antepartum level of NO2-/NO3- was markedly lower than the postpartum one(P<O. ol ). ③There was a negative correlation between the level of plasma NO2- /NO3- and systolic blood pressurein patients with PIH (P<0. 01). ④ A positive correlation was found between the level of plasma NO2-/NO3- andthat of cGMP in patients with PIH (P<0. 01). Conclusion: The decrease of NO synthesis may play an importantrole in occurrence of PIH.展开更多
A mathematical model for the inactivation of nitric oxide by rat cerebellar slices under non-steady state condition has been analyzed. This diffusion-inactivation model was used to estimate the kinetics of NO consumpt...A mathematical model for the inactivation of nitric oxide by rat cerebellar slices under non-steady state condition has been analyzed. This diffusion-inactivation model was used to estimate the kinetics of NO consumption by the rat cerebellar slices. He’s Homotopy perturbation method is used to solve the first order nonlinear differential equations which describe the concentrations given by net of diffusion and inactivation by the slices. Analytical expressions for the concentration of nitric oxide have been derived for all values of parameters. The obtained analytical results are compared with the simulation results (Matlab/Scilab program) and are found to be in good agreement.展开更多
Tumor promoters, apoptosis and autophagy modulators, chemotherapy drugs, and endogenous steroids demonstrate molecular similarity relative to cyclic nucleotide structure. This study explores relative molecular similar...Tumor promoters, apoptosis and autophagy modulators, chemotherapy drugs, and endogenous steroids demonstrate molecular similarity relative to cyclic nucleotide structure. This study explores relative molecular similarity within established human carcinogen structures using computational chemistry software. Molecular structures of conventional carcinogenic drugs and industrial agents demonstrate molecular similarity with a focus on the guanine base and nucleotide cyclized ring. Structures of volatile and gaseous anesthetic carcinogens do not conform to conventional 3-point pharmacophore-based fits characteristic of receptor-binding drugs. The results of this study provide some insight into how carcinogen structures may interact with endogenous compounds to disrupt cyclic nucleotide-driven homeostatic mechanisms.展开更多
Adrenocorticotropin hormone (ACTH), which is secreted in response to psychological stress, plays an important role in the hair cycle. This study examined the mechanism by which ACTH affects the hair cycle using mice d...Adrenocorticotropin hormone (ACTH), which is secreted in response to psychological stress, plays an important role in the hair cycle. This study examined the mechanism by which ACTH affects the hair cycle using mice deficient in melanocortin receptor-2(MC2R<sup>-/-</sup>), which is a main receptor for ACTH. We observed the hair cycle using female MC2R<sup>-/-</sup> mice at 15 weeks old and five days old to determine whether there were any age-dependent differences. The 15-week-old MC2R<sup>-/-</sup> mice showed the anagen phase for all mice. On the other hand, all of the MC2R<sup>+/+</sup> mice showed the telogen phase at the same age. Moreover, in the five-day-old mice, the hair growth of the MC2R<sup>-/-</sup> mice occurred earlier than in the MC2R<sup>+/+</sup> mice. Both the 15-week-old and five-day-old MC2R<sup>-/-</sup> mice had higher levels of ACTH and alpha-melanocyte stimulating hormone in the blood than did the MC2R<sup>+/+</sup> mice. In addition, in the 15-week-old MC2R<sup>-/-</sup> mice, the hair cycle shifted to the telogen phase following the administration of a cyclic guanosine monophosphate (cGMP) inhibitor and MC1R/MC5R inhibitor. In the five-day-old MC2R<sup>-/-</sup> mice, the hair growth was slowed by the administration of corticosterone. These results suggest that the ACTH/MC2R system has an important role in the hair cycle.展开更多
基金supported by the National Natural Science Foundation of China(No.20872078)the Basic Science Research Foundation of Tsinghua University(No.JC 2001046)
文摘An efficient and novel method for synthesizing 3′,5′-dithio-2′-deoxyguanosine was described.In this method normal guanosine was used as the starting material.A very efficient procedure was used to synthesize 2-O-tosylguanosine 1,which used 0.1 eq.DBTO instead of 2 eq.1 was treated with LTBH to give 9-(2-deoxy-β-D-threo-pentofuranosyl)guanine 2.2 could be easily turned to the target compound.
文摘AIM To investigate the potential effect of inhibitors of phosphodiesterase-5(PDE-5) for therapy of portal hypertension in liver cirrhosis.METHODS In the rat model of thioacetamide-induced liver fibrosis/cirrhosis the nitric oxide-cyclic guanosine monophosphate(NO-cGMP) pathway was investigated. Expression and localization of PDE-5, the enzyme that converts vasodilating cGMP into inactive 5'-GMP, was in the focus of the study. Hepatic gene expression of key components of the NO-cGMP pathway was determined by qRT-PCR: Endothelial NO synthase(eNOS), inducible NO synthase(iNOS), soluble guanylate cyclase subunits α1 and β1(sGCa1, sGCb1), and PDE-5. Hepatic PDE-5 protein expression and localization were detected by immunohistochemistry. Serum cGMP concentrations were measured using ELISA. Acute effects of the PDE-5 inhibitor Sildenafil(0.1 mg/kg or 1.0 mg/kg) on portal and systemic hemodynamics were investigated using pressure transducers.RESULTS Hepatic gene expression of eNOS(2.2-fold; P = 0.003), sGCa1(1.7-fold; P = 0.003), sGCb1(3.0-fold; P = 0.003), and PDE-5(11-fold; P = 0.003) was increased in cirrhotic livers compared to healthy livers. Overexpression of PDE-5(7.7-fold; P = 0.006) was less pronounced in fibrotic livers. iNOS expression was only detected in fibrotic and cirrhotic livers. In healthy liver, PDE-5 protein was localized primarily in zone 3 hepatocytes and to a lesser extent in perisinusoidal cells. This zonation was disturbed in cirrhosis: PDE-5 protein expression in perisinusoidal cells was induced approximately 8-fold. In addition, PDE-5-expressing cells were also found in fibrous septa. Serum cGMP concentrations were reduced in rats with cirrhotic livers by approximately 40%. Inhibition of PDE-5 by Sildenafil caused a significant increase in serum cGMP concentrations [+ 64% in healthy rats(P = 0.024), + 85% in cirrhotic rats(P = 0.018)]. Concomitantly, the portal venous pressure was reduced by 19% in rats with liver cirrhosis. CONCLUSION Overexpression and abrogated zonation of PDE-5 likely contribute to the pathogenesis of cirrhotic portal hypertension. PDE-5 inhibition may therefore be a reasonable therapeutic approach for portal hypertension.
基金funding from Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq#403120/2012-8,#308723/2013-9,#449436/2014-4)Coordenacao de Aperfeicoamento de Pessoal de Nível Superior(CAPES),Brazil
文摘Purines have a recognized importance as intercellular messengers.These molecules play an important role in the development and maintenance of the central nervous system(CNS),as well as in its response to pathological conditions.Both adenine and guanine-based purines can be released from astrocytes,where they play a relevant role as extracellular signaling molecules.Particularly,the nucleoside guanosine has been proposed as an extracellular molecule
基金supported by the Yunnan Provincial Science and Technology Department Science and Technology Plan Project (202101AZ070001-064).
文摘Background:This study aims to investigate the therapeutic effect of Wa medicine Niang-Mu-Liang medicinal liquor(NML)on rats with diabetes mellitus erectile dysfunction(DMED)and its impact on the ferroptosis signaling pathway.Methods:Thirty Sprague-Dawley rats were randomly divided into three groups:Control,DMED,and NML.After establishing the DMED model,treatments were administered for 8 weeks.After the administration,apomorphine hydrochloride tests were conducted to measure the mass and organ index of testes and epididymides,sperm concentration and viability in each group.Penile corpus cavernosum tissues were stained with hematoxylin and eosin.Nitric oxide and cyclic guanosine monophosphate levels in the penile corpus cavernosum tissues were determined using biochemical kits and enzyme-linked immunosorbent assay,while the expression of proteins related to the ferroptosis signaling pathway was measured by Western blot.Results:Compared to the DMED group,the DMED rats treated with NML showed significantly increased erection frequency,testicular and epididymal mass and index,sperm count and viability,along with noticeable improvement in the pathological morphology of penile corpus cavernosum.The content of nitric oxide and cyclic guanosine monophosphate,and the expression of ferritin heavy chain,ferritin light chain,and glutathione peroxidase 4 proteins in penile corpus cavernosum tissue were elevated,while the expression of transferrin and STEAP3 proteins was reduced.Conclusion:NML can improve erectile function in DMED rats by inhibiting the ferroptosis signaling pathway.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 20673002, 20733001)the 973 Project (2006CB910304)
文摘Nucleotide-specific fluorescence quenching in fluorescently labeled DNA has many applications in biotechnology. We have studied the inter-and intra-molecular quenching of tetramethylrhodamine (TMR) by nucleotides to better understand their quenching mechanism and influencing factors. In agreement with previous work, dGMP can effectively quench TMR, while the quenching of TMR by other nucleotides is negligible. The Stern-Volmer plot between TMR and dGMP delivers a bimolecular quenching constant of Ks=52.3 M-1. The fluorescence of TMR in labeled oligonucleotides decreases efficiently through photoinduced electron transfer by guanosine. The quenching rate constant between TMR and guanosine was measured using fluorescence correlation spectroscopy (FCS). In addition, our data show that the steric hindrance by bases around guanosine has significant effect on the G-quenching. The availability of these data should be useful in designing fluorescent oligonucleotides and understanding the G-quenching process.
文摘The study on the interaction of cisplatin with guanosine in neutral solution by 13C NMR spectroscopy has shown that besides the formation of [Pt（NH3）2（N7-Guo）2]2+, a new 1:1 complex [Pt（NH3）2(N7.N1-GuoH-1)]nn+, in which deprotonated guanosine was bonded to platium by N1 and N7 atoms, was also formed. Recently we have succeed-
基金supported by National Natural Science Foundation of China (NSFC) (Nos.21172010,21002004)
文摘Deamination is a crucial step in the transformation of 6-cyclopropylamino guanosine prodrug to its active form. A convenient method using capillary electrophoresis(CE) without sample labeling was developed to analyze the deamination of a series of D-/L-6-cyclopropylamino guanosine analogs by mouse liver homogenate, mouse liver microsome, and adenosine deaminase(ADA). A two-step process involving a 6-amino guanosine intermediate formed by oxidative N-dealkylation was demonstrated in the metabolism of 6-cyclopropylamino guanosine to 6-hydroxy guanosine. The results indicated that the transformation rates of different prodrugs to the active form varied greatly, which were closely correlated with the configuration of nucleosides and the structure of glycosyl groups. Most importantly,D-form analogs were metabolized much faster than their L-counterparts, thus clearly pointed out that compared to guanine, modification of glycosyl part might be a better choice for the development of L-guanosine analogs for the treatment of HIV.
基金supported by the National Natural Science Foundation of China(nos.21722803,91853119,21572169,21721005,91753201,21877086 and 21672165)the Hubei Natural Science Foundation for Distinguished Young Scholars(2019CFA064)+2 种基金the National Major Scientific and Technological Special Project for“Significant New Drugs Development”(2017ZX09303013)the Fundamental Research Funds for the Central Universities(2042019kf0189)the Natural Science Innovation Foundation of Wuhan University.
文摘While 8-oxo-7,8-dihydro-2′-deoxyguanosine(dOG)on DNA G-quadruplex(G4)has been studied,the influence of 8-oxo-7,8-dihydro-guanosine(rOG)lesions on telomeric repeat-containing RNA(TERRA)G4 deserves an in-depth study.The single-strand and guanine-rich characters of TERRA make it vulnerable to form rOG lesions.Our current study demonstrated that rOG located in the internal layer and external layer of TERRA impacted the G4 stability in different ways and perturbed RNA replication,as well as base-pair strength and stability.
基金funded by the Universiti Tunku Abdul Rahman Research fund(IPSR/RMC/UTARRF/2019-C2/L08)。
文摘Objective:To investigate the effect of epigallocatechin-3-gallate(EGCG)on endothelial dysfunction in spontaneously hypertensive rats(SHR).Methods:Wistar-Kyoto(WKY)rats and SHR were divided into four groups;WKY control,SHR control and SHR treated with EGCG(50 mg/kg/day)or losartan(10 mg/kg/day).The treatment was given daily for 4 weeks by oral gavage and the blood pressure was monitored by tail-cuff method every 3 days.Acetylcholineinduced endothelium-dependent relaxations were assessed in isolated phenylephrine-precontracted aortic rings at the end of treatment.The vascular levels of reactive oxygen species,nitric oxide,tetrahydrobiopterin,and cyclic guanosine monophosphate were also measured.Moreover,the expression of angiotensinⅡtype 1(AT_(1))receptor protein was determined.Results:The systolic blood pressure was significantly decreased in SHR treated with EGCG.The impaired endothelium-dependent relaxation was significantly improved in aortic ring isolated from the EGCG-treated SHR group.EGCG also significantly increased the levels of nitric oxide,tetrahydrobiopterin,and cyclic guanosine monophosphate,while decreasing the level of reactive oxygen species and the protein expression of AT_(1)receptor in SHR.Conclusions:EGCG attenuates endothelial dysfunction in SHR by decreasing oxidative stress and increasing vascular nitric oxide bioavailability,which may be modulated partly by inhibition of vascular AT_(1)receptors.An increase in endothelium-dependent relaxation may contribute to a decrease in blood pressure in hypertensive animals.
基金Supported by Synergy Pharmaceuticals Inc.,which provided the funding and the plecanatide,dolcanatide and placebo used for these studies
文摘AIM To investigate the effects of plecanatide and dolcanatide on maintenance of paracellular permeability, integrity of tight junctions and on suppression of visceral hypersensitivity. METHODS Transport of fluorescein isothiocyanate(FITC)-dextran was measured to assess permeability across cell monolayers and rat colon tissues. Effects of plecanatide and dolcanatide on the integrity of tight junctions in Caco-2 and T84 monolayers and on the expression and localization of occludin and zonula occludens-1(ZO-1) were examined by immunofluorescence microscopy. Anti-nociceptive activity of these agonists was evaluated in trinitrobenzene sulfonic acid(TNBS)-induced inflammatory as well as in non-inflammatory partial restraint stress(PRS) rat models. Statistical significance between the treatment groups in the permeability studies were evaluated using unpaired t-tests.RESULTS Treatment of T84 and Caco-2 monolayers with lipopolysaccharide(LPS) rapidly increased permeability, which was effectively suppressed when monolayers were also treated with plecanatide or dolcanatide. Similarly, when T84 and Caco-2 monolayers were treated with LPS, cell surface localization of tight junction proteins occludin and ZO-1 was severely disrupted. When cell monolayers were treated with LPS in the presence of plecanatide or dolcanatide, occludin and ZO-1 were localized at the cell surface of adjoining cells, similar to that observed for vehicle treated cells. Treatment of cell monolayers with plecanatide or dolcanatide without LPS did not alter permeability, integrity of tight junctions and cell surface localization of either of the tight junction proteins. In rat visceral hypersensitivity models, both agonists suppressed the TNBS-induced increase in abdominal contractions in response to colorectal distension without affecting the colonic wall elasticity, and both agonists also reduced colonic hypersensitivity in the PRS model. CONCLUSION Our results suggest that activation of GC-C signaling might be involved in maintenance of barrier function, possibly through regulating normal localization of tight junction proteins. Consistent with these findings, plecanatide and dolcanatide showed potent antinociceptive activity in rat visceral hypersensitivity models. These results imply that activation of GC-C signaling may be an attractive therapeutic approach to treat functional constipation disorders and inflammatory gastrointestinal conditions.
文摘BACKGROUND Changes in N-linked glycosylation have been observed in the circulation of individuals with hepatocellular carcinoma. In particular, an elevation in the level of core fucosylation has been observed. However, the mechanisms through which core fucose is increased are not well understood. We hypothesized that a review of the literature and related bioinformatic review regarding six genes known to be involved in the attachment of core fucosylation, the synthesis of the fucosylation substrate guanosine diphosphate(GDP)-fucose, or the transport of the substrate into the Golgi might offer mechanistic insight into the regulation of core fucose levels.AIM To survey the literature to capture the involvement of genes regulating core Nlinked fucosylation in hepatocellular carcinoma METHODS The PubMed biomedical literature database was searched for the association of hepatocellular carcinoma and each of the core fucose-related genes and their protein products. We also queried The Cancer Genome Atlas Liver hepatocellular carcinoma(LIHC) dataset for genetic, epigenetic and gene expression changes for the set of six genes using the tools at cBioportal.RESULTS A total of 27 citations involving one or more of the core fucosylation-related genes(FPGT, FUK, FUT8, GMDS, SLC35 C1, TSTA3) and hepatocellular carcinoma were identified. The same set of gene symbols was used to query the371 patients with liver cancer in the LIHC dataset to identify the frequency of m RNA over or under expression, as well as non-synonymous mutations, copy number variation and methylation level. Although all six genes trended to moresamples displaying over expression relative to under-expression, it was noted that a number of tumor samples had undergone amplification of the genes of the de novo synthesis pathway, GMDS(27 samples) and TSTA3(78 samples). In contrast, the other four genes had undergone amplification in 2 or fewer samples.CONCLUSION Amplification of genes involved in the de novo pathway for generation of GDPfucose, GMDS and TSTA3, likely contributes to the elevated core fucose observed in hepatocellular carcinoma.
基金Supported by NIH,No.R01CA170533,No.R01CA206026 and No.P30CA56036Targeted Diagnostic and Therapeutics,Inc.+2 种基金a Ruth L.Kirschstein National Research Service Award for Individual Predoctoral MD/PhD Fellows from the NIH,No.CA180500(To Blomain ES)a Ruth L.Kirschstein National Research Service Award for Individual Predoctoral MD/PhD Fellows from the NIH,No.F30 DK103492(To Merlino DJ)a Predoctoral Fellowship in Pharmacology/Toxicology from the PhR MA Foundation
文摘Colorectal cancer(CRC) is a major cause of cancerrelated mortality and morbidity worldwide. While improved treatments have enhanced overall patient outcome, disease burden encompassing quality of life, cost of care, and patient survival has seen little benefit. Consequently, additional advances in CRC treatments remain important, with an emphasis on preventative measures. Guanylyl cyclase C(GUCY2C), a transmembrane receptor expressed on intestinal epithelial cells, plays an important role in orchestrating intestinal homeostatic mechanisms. These effects are mediated by the endogenous hormones guanylin(GUCA2A) and uroguanylin(GUCA2B), which bind and activate GUCY2 C to regulate proliferation, metabolism and barrier function in intestine. Recent studies have demonstrated a link between GUCY2 C silencing and intestinal dysfunction, including tumorigenesis. Indeed, GUCY2 C silencing by the near universal loss of its paracrine hormone ligands increases colon cancer susceptibility in animals and humans. GUCY2C's role as a tumor suppressor has opened the door to a new paradigm for CRC prevention by hormone replacement therapy using synthetic hormone analogs, such as the FDA-approved oral GUCY2 C ligand linaclotide(Linzess^(TM)). Here we review the known contributions of the GUCY2 C signaling axis to CRC, and relate them to a novel clinical strategy targeting tumor chemoprevention.
文摘The aim of the current study was to investigate the pharmacological activity of glabridinon the isolated human saphenous vein (SV) and explore the underlying mechanisms. Samples of patients' SVs were removed during bypass surgery, and 4-mm lengths of the vessels were placedin Krebs solution at ±4℃ and hung in an isolated organ bath to assess their contraction/relaxationresponses. The contraction/relaxation responses were recorded to observe if the cyclic guanosinemonophosphate (cGMP)/protein kinase G (PKG) pathway mediates the relaxant effect of glabridinafter treatment with blockers like ODQ (a guanylate cyclase inhibitor), KT5823 (a PKG inhibitor),isobutylmethylxanthine [IBMX, a phosphodiesterase (PDE) inhibitor], and cantharidin [Cant,a myosin light-chain phosphatase (MLCP) inhibitor]. Moreover, nitric oxide (NO), cGMP, andPKG levels in SV tissues were determined by ELISA after incubation with glabridin, N(o)-nitro-L-arginine methyl ester (L-Name, a NO synthetase inhibitor), phenylephrine (PE), ODQ, IBMX,and KT5823. The results showed that glabridin relaxed the vascular smooth muscle of humanSV pretreated with PE in a dose-dependent manner, which was independent of the endothelium.The vasorelaxant effect of glabridin was only inhibited by iberiotoxin (IbTX), Cant, and KT5823.Glabridin increased cGMP and PKG levels in SV homogenates, whereas it did not alter the NOlevel. The enhancing efects of cGMP and PKG levels by glabridin were abolished by ODQ andKT5823. In conclusion, glabridin has a vasorelaxant effect, which is associated with the activationof BKc. channels and inhibition of PDE.
文摘Carcinogenesis is associated with malfunction in the cGMP-mediated regulation of cytosolic Ca<sup>2+</sup> and reactive oxygen species. Chemotherapy resistant cancer cells are re-sensitised to apoptosis by the action of a substantial number of natural compounds on cell membrane multidrug resistant proteins. Chemical structures of pro-apoptotic and anti-apoptotic compounds demonstrate relative molecular similarity to cGMP. This study uses a computational chemistry program to investigate molecular similarity within cGMP and chemo-preventative structures. Chemotherapeutic drugs and resistance modulators provide multiple fits to a nucleotide template that differ in their relationship to the cyclised ring of cGMP. The alternative fits of drug and modulator structures may relate to the development and unblocking of apoptosis and drug resistance.
文摘Common abbreviations,acronyms and short names are listed below.These shortened forms,and otherabbreviations not in this list,should always be defined at first usage in both abstract and text.Some of themare well-known and can be used directly without confusion.
文摘Objective: To explore the role of nitric oxide (NO), an internal vasodilative factor, in occurrence ofpregnancy induced hypertension (PIH). Methods: The antepartum and postpartum levels of NO2-/NO3-, the stable metabolic end product of NO, and those of cyclic guanosine monophosphate (cGMP) in 30 patients with PIHand 30 healthy women in their late pregnancy were measured with greiss reagent. ResultS: ① The plasma levels ofNO2-/NO3- and cGMP were significantly decreased in patients with PIH as compared with the healthy women (P<0. 05). ②In patients with PlH, the antepartum level of NO2-/NO3- was markedly lower than the postpartum one(P<O. ol ). ③There was a negative correlation between the level of plasma NO2- /NO3- and systolic blood pressurein patients with PIH (P<0. 01). ④ A positive correlation was found between the level of plasma NO2-/NO3- andthat of cGMP in patients with PIH (P<0. 01). Conclusion: The decrease of NO synthesis may play an importantrole in occurrence of PIH.
文摘A mathematical model for the inactivation of nitric oxide by rat cerebellar slices under non-steady state condition has been analyzed. This diffusion-inactivation model was used to estimate the kinetics of NO consumption by the rat cerebellar slices. He’s Homotopy perturbation method is used to solve the first order nonlinear differential equations which describe the concentrations given by net of diffusion and inactivation by the slices. Analytical expressions for the concentration of nitric oxide have been derived for all values of parameters. The obtained analytical results are compared with the simulation results (Matlab/Scilab program) and are found to be in good agreement.
文摘Tumor promoters, apoptosis and autophagy modulators, chemotherapy drugs, and endogenous steroids demonstrate molecular similarity relative to cyclic nucleotide structure. This study explores relative molecular similarity within established human carcinogen structures using computational chemistry software. Molecular structures of conventional carcinogenic drugs and industrial agents demonstrate molecular similarity with a focus on the guanine base and nucleotide cyclized ring. Structures of volatile and gaseous anesthetic carcinogens do not conform to conventional 3-point pharmacophore-based fits characteristic of receptor-binding drugs. The results of this study provide some insight into how carcinogen structures may interact with endogenous compounds to disrupt cyclic nucleotide-driven homeostatic mechanisms.
文摘Adrenocorticotropin hormone (ACTH), which is secreted in response to psychological stress, plays an important role in the hair cycle. This study examined the mechanism by which ACTH affects the hair cycle using mice deficient in melanocortin receptor-2(MC2R<sup>-/-</sup>), which is a main receptor for ACTH. We observed the hair cycle using female MC2R<sup>-/-</sup> mice at 15 weeks old and five days old to determine whether there were any age-dependent differences. The 15-week-old MC2R<sup>-/-</sup> mice showed the anagen phase for all mice. On the other hand, all of the MC2R<sup>+/+</sup> mice showed the telogen phase at the same age. Moreover, in the five-day-old mice, the hair growth of the MC2R<sup>-/-</sup> mice occurred earlier than in the MC2R<sup>+/+</sup> mice. Both the 15-week-old and five-day-old MC2R<sup>-/-</sup> mice had higher levels of ACTH and alpha-melanocyte stimulating hormone in the blood than did the MC2R<sup>+/+</sup> mice. In addition, in the 15-week-old MC2R<sup>-/-</sup> mice, the hair cycle shifted to the telogen phase following the administration of a cyclic guanosine monophosphate (cGMP) inhibitor and MC1R/MC5R inhibitor. In the five-day-old MC2R<sup>-/-</sup> mice, the hair growth was slowed by the administration of corticosterone. These results suggest that the ACTH/MC2R system has an important role in the hair cycle.
