Relative Bioavailability of DL and L-Methionine in Broilers

Studies on the relative bioavailability (RBV) of DL-Methionine (DL-Met) to L-Methionine (L-Met) have produced variable results. An experiment was conducted to determine the RBV of DL to L-Met. A total of 2268 1-day old male chicken were housed in 54 floor pens (42 bird/pen). There were 9 treatments (6 repetitions) including the basal diet (BD). The BD was deficient in Met content with 0.27, 0.26 and 0.25 in the starter, grower and finisher periods respectively. Four levels of experimental diets for each DL-Met and L-Met were created by supplementing 0.05%, 0.10%, 0.15% and 0.20% of DL- or L-Met to the BD. The feeding program consisted of starter (0-14 d, 21% CP and 2900 kcal ME/kg), grower (15 - 28 d, 20% CP and 3000 kcal ME/kg) and finisher period (29 - 37 d, 18.5% CP and 3050 kcal ME/kg). Chickens and feed were weighed at the end of each age period. Regression coefficients of a common plateau asymptotic regression were used to calculate RBV. Birds responded to gradual increase in Met levels, BW, FCR and ADG were significantly (P 0.05) higher in treatment groups as compared to control. Through the study period (37 d), the RBVs of DL-Met for BW and FCR were 89 and 77 respectively.

Dissecting molecular mechanisms underlying ferroptosis in human umbilical cord mesenchymal stem cells:Role of cystathionineγ-lyase/hydrogen sulfide pathway

BACKGROUND Ferroptosis can induce low retention and engraftment after mesenchymal stem cell(MSC)delivery,which is considered a major challenge to the effectiveness of MSC-based pulmonary arterial hypertension(PAH)therapy.Interestingly,the cystathionineγ-lyase(CSE)/hydrogen sulfide(H_(2)S)pathway may contribute to mediating ferroptosis.However,the influence of the CSE/H_(2)S pathway on ferroptosis in human umbilical cord MSCs(HUCMSCs)remains unclear.AIM To clarify whether the effect of HUCMSCs on vascular remodelling in PAH mice is affected by CSE/H_(2)S pathway-mediated ferroptosis,and to investigate the functions of the CSE/H_(2)S pathway in ferroptosis in HUCMSCs and the underlying mechanisms.METHODS Erastin and ferrostatin-1(Fer-1)were used to induce and inhibit ferroptosis,respectively.HUCMSCs were transfected with a vector to overexpress or inhibit expression of CSE.A PAH mouse model was established using 4-wk-old male BALB/c nude mice under hypoxic conditions,and pulmonary pressure and vascular remodelling were measured.The survival of HUCMSCs after delivery was observed by in vivo bioluminescence imaging.Cell viability,iron accumulation,reactive oxygen species production,cystine uptake,and lipid peroxidation in HUCMSCs were tested.Ferroptosis-related proteins and S-sulfhydrated Kelchlike ECH-associating protein 1(Keap1)were detected by western blot analysis.RESULTS In vivo,CSE overexpression improved cell survival after erastin-treated HUCMSC delivery in mice with hypoxiainduced PAH.In vitro,CSE overexpression improved H_(2)S production and ferroptosis-related indexes,such as cell viability,iron level,reactive oxygen species production,cystine uptake,lipid peroxidation,mitochondrial membrane density,and ferroptosis-related protein expression,in erastin-treated HUCMSCs.In contrast,in vivo,CSE inhibition decreased cell survival after Fer-1-treated HUCMSC delivery and aggravated vascular remodelling in PAH mice.In vitro,CSE inhibition decreased H_(2)S levels and restored ferroptosis in Fer-1-treated HUCMSCs.Interestingly,upregulation of the CSE/H_(2)S pathway induced Keap1 S-sulfhydration,which contributed to the inhibition of ferroptosis.CONCLUSION Regulation of the CSE/H_(2)S pathway in HUCMSCs contributes to the inhibition of ferroptosis and improves the suppressive effect on vascular remodelling in mice with hypoxia-induced PAH.Moreover,the protective effect of the CSE/H_(2)S pathway against ferroptosis in HUCMSCs is mediated via S-sulfhydrated Keap1/nuclear factor erythroid 2-related factor 2 signalling.The present study may provide a novel therapeutic avenue for improving the protective capacity of transplanted MSCs in PAH.

PURIFICATION OF L-METHIONINE AND N-ACETYL-D-METHIONINE FROM THE MIXTURE OF ENZYMATICALLY DEACYLATED N-ACETYL-DL-METHIONINE

N-acetyl-D-methionine, NaAc and the remains of N-acetyl-L-methionine dramatically affect the purification of L-methionine when purified from the mixture of enzymatically deacylated N-acetyl-DL-methionine, leading to a low yield conventionally. Here, this paper reports a successful separation and purification of both L-methionine and N-acetyl-D-methionine by an H ion-exchange column. The pH, L-Met concentration and the ratio between the content of sodium cation and the ion-exchange capacity were optimized to obtain the maximum yield. Experimental results indicate that, under the optimized conditions, the yields of L-methionine and N-acetyl-D-methionine can reach as high as 85% and 75%, respectively.

A Facile Synthetic Route to L-Phosphinothricin

A convenient and effective method for synthesis of L-phosphinothricin was described. The highlight was involved in a simple access to the key intermediate L-2-amino-4-chlorobutyric acid derivative from the inexpensive L-methionine.

Relationship between cystathionine γ-lyase gene polymorphism and essential hypertension in Northern Chinese Han population

Background Hydrogen sulfide （H2S） plays an important role in the smooth muscle cell relaxation and thereby participates in the development of hypertension. Cystathionine γ-lyase is the key enzyme in the endogenous production of H2S. Up to now, the reports on the relationship between the polymorphisms of cystathionine γ-lyase gene （CTH） and essential hypertension （EH） are limited. This study was designed to assess their underlying relationship. Methods A total of 503 hypertensive patients and 490 age-, gender- and area-matched normotensive controls were enrolled in this study. Based on the FASTSNP, a web server to identify putative functional single nucleotide polymorphisms （SNPs） of genes, we selected two SNPs, rs482843 and rs1021737, in the CTH gene for genotyping. Genotyping was performed by the polymerase chain reaction and restriction fragment length polymorphism method （PCR-RFLP）. The frequencies of the alleles and genotypes between cases and controls were compared by the chi-square test. The program Haplo.stats was used to investigate the relationship between the haplotypes and EH. Results These two SNPs were in Hardy-Weinberg Equilibrium in both cases and controls. The genotype distribution and allele frequencies of them did not significantly differ between cases and controls （all P〉0.05）. In the stepwise logistic regression analysis we failed to observe their association with hypertension. In addition, none of the four estimated haplotypes or diplotypes significantly increased or decreased the risk of hypertension before or after adjustment for several known risk factors. Conclusions The present study suggests that the SNPs rs482843 and rs1021737 of the CTH gene were not associated with essential hypertension in the Northern Chinese Han population. However, replications in other populations and further functional studies are still necessary to clarify the role of the CTH gene in the pathogenesis of EH.

Cystathionine-γ-lyase ameliorates the histone demethylase JMJD3-mediated autoimmune response in rheumatoid arthritis

Cystathionine-γ-lyase(CSE),an enzyme associated with hydrogen sulfide(H2S)production,is an important endogenous regulator of inflammation.Jumonji domain-containing protein 3(JMJD3)is implicated in the immune response and inflammation.Here,we investigated the potential contribution of JMJD3 to endogenous CSE-mediated inflammation in rheumatoid arthritis(RA).Upregulated CSE and JMJD3 were identified in synovial fibroblasts(SFs)from RA patients as well as in the joints of arthritic mice.Knocking down CSE augmented inflammation in IL-1β-induced SFs by increasing JMJD3 expression.In addition,CSE−/−mice with collagen-induced arthritis(CIA)developed severe joint inflammation and bone erosion.Conversely,overexpressing CSE inhibited JMJD3 expression by the transcription factor Sp-1 and was accompanied by reduced inflammation in IL-1β-treated SFs.Furthermore,JMJD3 silencing or the administration of the JMJD3 inhibitor GSK-J4 significantly decreased the inflammatory response in IL-1β-treated SFs,mainly by controlling the methylation status of H3K27me3 at the promoter of its target genes.GSK-J4 markedly attenuated the severity of arthritis in CIA mice.In conclusion,suppressing JMJD3 expression by the transcription factor Sp-1 is likely responsible for the ability of CSE to negatively modulate the inflammatory response and reduce the progression of RA.

Therapeutic importance of hydrogen sulfide in age-associated neurodegenerative diseases

Hydrogen sulfide(H2S)is a gasotransmitter that acts as an antioxidant and exhibits a wide variety of cytoprotective and physiological functions in age-associated diseases.One of the major causes of age-related diseases is oxidative stress.In recent years,the importance of H2S has become clear,although its antioxidant function has not yet been fully explored.The enzymes cystathionineβ-synthase,cystathionineγ-lya-se,and 3-mercaptopyruvate sulfurtransferase are involved in the enzymatic production of H2S.Previously,H2S was considered a neuromodulator,given its role in long-term hippocampal potentiation,but it is now also recognized as an antioxidant in age-related neurodegeneration.Due to aerobic metabolism,the central nervous system is vulnerable to oxidative stress in brain aging,resulting in age-associated degenerative diseases.H2S exerts its antioxidant effect by limiting free radical reactions through the activation of antioxidant enzymes,including superoxide dismutase,catalase,and glutathione peroxidase,which protect against the effects of aging by regulating apoptosis-related genes,including p53,Bax,and Bcl-2.This review explores the implications and mechanisms of H2S as an antioxidant in age-associated neurodegenerative diseases,including Alzheimer’s disease,Parkinson’s disease,Huntington’s disease,and Down syndrome.

Role of hydrogen sulfide in portal hypertension and esophagogastric junction vascular disease

AIM: To investigate the association between endogenous hydrogen sulfide (H2S) and portal hypertension as well as its effect on vascular smooth muscle cells.

17α-hydroxylase/17,20 carbon chain lyase deficiency caused by p.Tyr329fs homozygous mutation:Three case reports

p.Tyr329fs is a cytochrome P450c17 mutation among Chinese individuals.However,data on 17-α-hydroxylase deficiency caused by cytochrome P450c17 p.Tyr329fs homozygous mutation are lacking.This paper is a case report of three patients homozygous for p.Tyr329fs who were diagnosed with 17-α-hydroxylase deficiency between 2005 and 2019.CASE SUMMARY Case 1 presented with hypertension,hypokalemia,sexual infantilism and delayed bone age.The patient had a 46,XY karyotype,was homozygous for p.Tyr329fs and was recently treated with dexamethasone 0.375 mg qn.Case 2 presented with hypokalemia,sexual infantilism,osteoporosis and delayed bone age.The patient had a 46,XY karyotype,was homozygous for p.Tyr329fs and was treated with dexamethasone 0.75 mg qn at the last follow-up.Serum potassium and blood pressure could be maintained within normal range for cases 1 and 2.Case 3 presented with amenorrhea,sexual infantilism,osteopenia and delayed bone age.The patient had a 46,XX karyotype,was homozygous for p.Tyr329fs and was treated with dexamethasone 0.75 mg qn and progynova 1 mg qd.Outpatient follow-up revealed an adrenocorticotropic hormone(8 AM)of<5.00 pg/mL.CONCLUSION The homozygous p.Tyr329fs mutation usually manifests as a combined deficiency,and definitive diagnosis depends primarily on genetic testing.

Tong xie yao fang relieves irritable bowel syndromein rats via mechanisms involving regulation of5-hydroxytryptamine and substance P

AIM To study the effect of hydrogen sulfide （H2S） onsevere acute pancreatitis （SAP） in a rat model.METHODS： Sprague-Dawley （SD） rats were administeredan intraperitoneal injection of saline containing20% L-Arg （250 mg/100 g） hourly for over 2 h to induceSAP. The rats were treated with DL-propargylglycine（PAG, 50 mg/kg） or different dosages of NaHS （5 mg/kg, 10 mg/kg, 20 mg/kg or 100 mg/kg）. PAG or NaHSwas administered 1 h before induction of pancreatitis.Rats were sacrificed 24 h after the last L-Arg injection.Blood and pancreas tissues were collected.RESULTS： The H2S and cystathionine-γ-lyase mRNAlevels in SAP rats were signi？cantly lower than thosein the control group, and treatment with PAG furtherreduced the H2S level. Nevertheless, H2S was significantlyincreased after NaHS administration compared with theSAP group, and the degree of upregulation was associatedwith the NaHS dosage. NaHS reduced the levels of plasmaamylase, interleukin-6 and myeloperoxidase in pancreatictissue. NaHS suppressed the degradation of IκBα and theactivity of nuclear factor-κB, as well as the phosphorylationof PI3K/AKT.CONCLUSION： H2S plays an anti-inflammatory role inSAP in vivo .

Amelioration of hepatotoxicity by biocleavable aminothiol chimeras of isoniazid: Design, synthesis, kinetics and pharmacological evaluation

AIM To overcome the hazardous effects on liver caused by long-term use of antitubercular agent isoniazid(INH) by developing a novel hepatoprotective prodrug strategy by conjugating INH with aminothiols as antioxidant promoities for probable synergistic effect.METHODS INH was conjugated with N-acetyl cysteine(NAC) and N-(2)-mercaptopropionyl glycine using the SchottenBaumann reaction and with L-methionine using Boc-anhydride through a biocleavable amide linkage. Synthesized prodrugs were characterized by spectral analysis, and in vitro and in vivo release studies were carried out using HPLC. Their hepatoprotective potential was evaluated in male Wistar rats by performing liver function tests, measuring markers of oxidative stress and carrying out histopathology studies.RESULTS Prodrugs were found to be stable in acidic(pH 1.2) and basic(pH 7.4) buffers and in rat stomach homogenates, whereas they were hydrolysed significantly(59.43%-94.93%) in intestinal homogenates over a period of 6 h. Upon oral administration of prodrug NI to rats, 52.4%-61.3% INH and 47.4%-56.8% of NAC were recovered in blood in 8-10 h. Urine and faeces samples pooled over a period of 24 h exhibited 1.3%-2.5% and 0.94%-0.9% of NAC, respectively, without any presence of intact NI or INH. Prodrugs were biologically evaluated for hepatoprotective activity. All the prodrugs were effective in abating oxidative stress and re-establishing the normal hepatic physiology. The effect of prodrug of INH with NAC in restoring the levels of the enzymes superoxide dismutase and glutathione peroxidase and abrogating liver damage was noteworthy especially. CONCLUSION The findings of this investigation demonstrated that the reported prodrugs can add safety and efficacy to future clinical protocols of tuberculosis treatment.

Catalytic Activity of Amino Acids-Metal Complexes in Oxidation Reactions

Studies were carried out to determine the activity of complexes of the essential amino acids DL-Lysine and L-Methionine with heavy metals in the oxidation of cyclohexene with tert-butylhydroperoxide in toluene at 80°C. All complexes were prepared through interaction of metal ions and DL-Lysine and L-Methionine at room temperature in aqueous solutions. Only the complexes of Mo and W were obtained from acidic aqueous solution. These complexes were characterized by FT-IR, Moessbauer spectroscopy and EPR analysis. The products of the oxidation reactions were identified by GC/MS analysis. The complexes of Mo and V showed the best activity in the epoxidation reaction of cyclohexene in comparison with other complexes, such as Ni, Mn, Zn, Co, Cu, Cr, Fe and W. Using semi-empirical quantum-chemistry methods, the full energy of the Mo complexes was calculated and their probable structure is presented.

Changes in Hydrogen Sulfide in Rats with Hepatic Cirrhosis in Different Stages

This study aimed to observe changes in the hydrogen sulfide（H_2S） system in the blood and liver tissue of rats with hepatic cirrhosis at different stages by studying the effect of H_2S on the course of hyperdynamic circulation in rats with hepatic cirrhosis. H_2S concentration in the blood from the portal vein and inferior vena cava of hepatic cirrhosis rat model induced with carbon tetrachloride was detected on the 15 th, 30 th, and 52 nd day. The expression of cystathionine β-synthase（CBS） and cystathionine γ-lyase（CSE） protein, and CBS and CSE mRNA in the liver was detected by immunohistochemistry and reverse transcriptase polymerase chain reaction（RT-PCR）, respectively. The results indicated that H_2S concentration in the blood from the portal vein and inferior vena cava of rats with hepatic cirrhosis was significantly lower than that in the control group. H_2S was gradually decreased with the development of the disease and significantly lower in the blood from portal vein than in the blood of inferior vena cava at the mid-stage and the late stage groups. The expression levels of CBS and CSE protein, and CBS and CSE mR NA in the livers with hepatic cirrhosis at different stages were all higher than those in the control group, and the expression gradually increased with the development of the disease. The expression of CBS was lower than CSE in the same stages. The results indicated that the CSE mRNA was expressed predominantly in the cirrhosis groups as compared with CBS mRNA. Among experimental rats, the H_2S system has an important effect on the occurrence and development of hyperdynamic circulation in rats with hepatic cirrhosis. This finding adds to the literature by demonstrating that H_2S protects vascular remodelling in the liver, and that CSE is indispensable in this process.

The Role of Abnormalities Related to the One Carbon Cycle in Depression and Schizophrenia

This paper reviews our present knowledge of the role of the one-carbon cycle in mood disorder and schizophrenia with particular attention to S-adenosyl methionine (SAM). After an historical introduction the clinical data is first reviewed of the anti-depressant action of SAM, in particular a survey of double blind placebo-controlled trials. Then follows an account of the biochemical parameters of the action of SAM, in particular the role of folic acid and 5-methyltetrahydrofolate (vitamin B9), polyamines, homocysteine, together with epigenetic studies. In schizophrenia the effect of oral l-methionine on worsening the symptoms of some chronic schizophrenics has been known since 1961. Recent epigenetic research covered has addressed the mechanism of this reaction. This includes the role of SAM in modulating DNA methyltransferase-1 mRNA activity, cytosine 5-methylation, spine numbers and the expression of mRNAs encoding for reelin and GAD67 in GABAergic neurons in the frontal cortex in schizophrenia. There is also evidence that marker D8S542 located within the methionine sulfoxide reductase (MSRA) gene may be involved in schizophrenia as well as 677C > T polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene. The possible roles of homocysteine and methionine S-adenosyl transferase kinetics are also discussed.

Localization of the hydrogen sulfide and oxytocin systems at the depth of the sulci in a porcine model of acute subdural hematoma

In the porcine model discussed in this review,the acute subdural hematoma was induced by subdural injection of autologous blood over the left parietal cortex,which led to a transient elevation of the intracerebral pressure,measured by bilateral neuromonitoring.The hematoma-induced brain injury was associated with albumin extravasation,oxidative stress,reactive astrogliosis and microglial activation in the ipsilateral hemisphere.Further proteins and injury markers were validated to be used for immunohistochemistry of porcine brain tissue.The cerebral expression patterns of oxytocin,oxytocin receptor,cystathionine-γ-lyase and cystathionine-β-synthase were particularly interesting:these four proteins all co-localized at the base of the sulci,where pressure-induced brain injury elicits maximum stress.In this context,the pig is a very relevant translational model in contrast to the rodent brain.The structure of the porcine brain is very similar to the human:the presence of gyri and sulci(gyrencephalic brain),white matter to grey matter proportion and tentorium cerebelli.Thus,pressure-induced injury in the porcine brain,unlike in the rodent brain,is reflective of the human pathophysiology.

Pharmacological Prospects of Oxygenated Abietane-Type Diterpenoids from <i>Taxodium distichum</i>Cones

Eight naturally occurring diterpenoids, including 6,7-dehydroroyleanone, taxodal, taxodione, salvinolone, 14-deoxycoleon U, 5,6-dehydrosugiol, sandaracopimaric acid, and xanthoperol were isolated from Taxodium distichum cones and their biological properties evaluated in vitro against six different biological screening targets. Taxodione showed potent activity against a number of different targets, and salvinolone and 14-deoxycoleon U showed remarkable inhibitory activities against prolyl oligopeptidase (POP) and 17α-hydroxylase/C17,20-lyase (CYP17), respectively. These three compounds also showed strong cytotoxic activities against HL60 and K562 human leukemia cells. The structure-activity relationships of these compounds have also been considered. The findings in this study could lead to enhanced pharmacological prospects for the natural abietane-type diterpenoids consisting in conifer cones.

A Novel Cu(II) Complex with 2,2′-Bipyridyl and L-Methioninate──Synthesis, Characterization, Molecular Structure and Stability

The ternary Cu(II) complex with 2,2′-bipyridyl (bipy) and L-methioninate (L-Met) has been synthesized and characterized by elemental analysis, molar conductivity, UV-Vis spectra, IR spectra and pH-potentiometric titration methods. The structure of the complex [Cu(L-Met)(bipy)(H_2O)]ClO_4·3/8H_2O was characterized by the X-ray diffraction analysis. It crystallizes in the triclinic system, space group P1 with four molecules in a unit cell of dimensions, a=0.7656(2) nm, b=1.3142(3) nm, c=2.0596(4) nm, α=97.70(3)°, β=97.96(3)°, γ=94.33(3)°, V=2.0244(8) nm 3, R_1=0.0441 and wR_2=0.0678. The crystal contains four crystallographically independent [Cu(L-Met)(bipy)(H_2O)] + complexes (Cu1-Cu4), having a distorted square-pyramidal geometry with the same coordinated atoms around each copper center. The base plane is occupied by two nitrogen atoms of one bipy, the amino nitrogen atom and one carboxylate oxygen atom from each independent L-Met moiety, and one water oxygen at an axial position. Cu1 and Cu3 are essentially enantiomers of Cu2 and Cu4. The four molecules are packed with each other by intermolecular hydrogen-bonding and aromatic-ring stacking interactions.

Methionine sources and genotype affect embryonic intestinal development,antioxidants,tight junctions,and growth-related gene expression in chickens

Methionine(Met)is an essential and first limiting amino acid in the poultry diet that plays a significant role in chicken embryonic development and growth.The present study examined the effect of in ovo injection of DL-Met and L-Met sources and genotypes on chicken embryonic-intestinal development and health.Fertilized eggs of the two genotypes,TETRA-SL layer hybrid(TSL)—commercial layer hybrid and Hungarian Partridge colored hen breed(HPC)—a native genotype,were randomly distributed into four treatments for each genotype.The treatment groups include the following:1)control non-injected eggs(NoIn);2)saline-injected(SaIn);3)DL-Met injected(DLM);and 4)L-Met injected(LM).The in ovo injection was carried out on 17.5 d of embryonic development;after hatching,eight chicks per group were sacrificed,and the jejunum was extracted for analysis.The results showed that both DLM and LM groups had enhanced intestinal development as evidenced by increased villus width,villus height,and villus area(P<0.05)compared to the control.The DLM group had significantly reduced crypt depth,glutathione(GSH)content,glutathione S-transferase 3 alpha(GST3),occludin(OCLN)gene expression and increased villus height to crypt depth ratio in the TSL genotype than the LM group(P<0.05).The HPC genotype has overexpressed insulin-like growth factor 1(IGF1)gene,tricellulin(MD2),occludin(OCLN),superoxide dismutase 1(SOD1),and GST3 genes than the TSL genotype(P<0.05).In conclusion,these findings showed that in ovo injection of Met enhanced intestinal development,and function,with genotypes responding differently under normal conditions.Genotypes also influenced the expression of intestinal antioxidants,tight junction,and growth-related genes.

Electrophysiological effects of hydrogen sulfide on human atrial fibers

Background It has been reported that endogenous or exogenous hydrogen sulfide （H2S） exerts physiological effects in the vertebrate cardiovascular system. We have also demonstrated that H2S acts as an important regulator of electrophysiological properties in guinea pig papillary muscles and on pacemaker cells in sinoatrial nodes of rabbits. This study was to observe the electrophysiological effects of H2S on human atrial fibers. Methods Human atrial samples were collected during cardiac surgery. Parameters of action potential in human atrial specialized fibers were recorded using a standard intracellular microetectrode technique. Results NariS （H2S donor） （50, 100 and 200 pmol/L） decreased the amplitude of action potential （APA）, maximal rate of depolarization （Vmax）, velocity of diastolic （phase 4） depolarization （VDD） and rate of pacemaker firing （RPF）, and shortened the duration of 90% repolarization （APD90） in a concentration-dependent manner. ATP-sensitive K＋ （KATP） channel blocker glibenclamide （Gli, 20 μmol/L） partially blocked the effects of NariS （100 μmol/L） on human atrial fiber cells. The L-type Ca2＋ channel agonist Bay K8644 （0.5 μmol/L） also partially blocked the effects of NariS （100 μmol/L）. An inhibitor of cystathionine y-lyase （CSE）, DL-propargylglycine （PPG, 200 μmol/L）, increased APA, Vmax, VDD and RPF, and prolonged APDg0. Conclusions H2S exerts a negative chronotropic action and accelerates the repolarization of human atrial specialized fibers, possibly as a result of increases in potassium efflux through the opening of KATP channels and a concomitant decrease in calcium influx. Endogenous H2S may be generated by CSE and act as an important regulator of electrophysiological properties in human atrial fibers.

The in ovo injection of methionine improves intestinal cell proliferation and differentiation in chick embryos by activating the JAK2/STAT3 signaling pathway

The intestinal health of chick embryos is vital for their life-long growth,and exogenous nutrition intervention may provide sufficient nutrition for embryonic development.In the present study,we investigated the effect of in ovo injection of L-methionine(L-Met)on the intestinal structure and barrier function of chick embryos.There were 4 groups of treatments:the control(CON)group injected with phosphate-buffered saline(PBS)and the other 3 groups injected with 5,10,and 20 mg L-Met/egg,respectively.The injection was performed on embryonic day 9(E9),and intestinal samples were collected on the day of hatching for analysis.The results showed that,compared with the CON group,the groups administered an in ovo injection of L-Met increased relative weights of the duodenum,jejunum,and ileum(P<0.05).Hematoxylin and eosin(H&E)staining showed that the groups injected with 5,10,and 20 mg L-Met significantly increased villus height and crypt depth(P<0.05).Moreover,in ovo injection of 10 mg L-Met also increased the transepithelial electrical resistance(TEER)of the jejunum(P<0.05).Injection with 10 and 20 mg L-Met increased the expression of the tight junction proteins(ZO-1 and claudin-1)and the fluorescence signal intensity of Ki67 and villin proteins(P<0.05).Further,the protein expression of phospho-Janus kinase 2(p-JAK2)and phospho-signal transducer and activator of transcription 3(p-STAT3)was significantly increased by 10 or 20 mg L-Met injection(P<0.05).In conclusion,the injection of L-Met,especially at a dose of 10 mg,showed beneficial effects on the intestinal integrity of chick embryos due to the activation of the JAK2/STAT3 signaling pathway.Our results may provide new insights for regulating the intestinal development of embryonic chicks and the rapid growth of chicks after hatching.