Citric Acid-sodium Citrate Buffer Research Articles

Dapagliflozin Improves Angiogenesis after Hindlimb Ischemia through the PI3K-Akt-eNOS Pathway.

Recently, the vascular protective effect of anti-diabetic agents has been receiving much attention. Sodium glucose cotransporter 2 (SGLT2) inhibitors had demonstrated reductions in cardiovascular (CV) events. However, the therapeutic effect of dapagliflozin on angiogenesis in peripheral arterial disease was unclear. This study aimed to explore the effect and mechanism of dapagliflozin on angiogenesis after hindlimb ischemia. We first evaluated the effect of dapagliflozin on post-ischemic angiogenesis in the hindlimbs of rats. Laser doppler imaging was used to detect the hindlimb blood perfusion. In addition, we used immunohistochemistry to detect the density of new capillaries after ischemia. The relevant signaling pathways of dapagliflozin affecting post-ischemic angiogenesis were screened through phosphoproteomic detection, and then the mechanism of dapagliflozin affecting post-ischemic angiogenesis was verified at the level of human umbilical vein endothelial cells (HUVECs). After subjection to excision of the left femoral artery, all rats were randomly distributed into two groups: the dapagliflozin group (left femoral artery resection, receiving intragastric feeding with dapagliflozin (1 mg/kg/d), for 21 consecutive days) and the model group, that is, the positive control group (left femoral artery resection, receiving intragastric feeding with citric acid-sodium citrate buffer solution (1 mg/kg/d), for 21 consecutive days). In addition, the control group, that is the negative control group (without left femoral artery resection, receiving intragastric feeding with citric acid-sodium citrate buffer solution (1 mg/kg/d), for 21 consecutive days) was added. At day 21 post-surgery, the dapagliflozin-treatment group had the greatest blood perfusion, accompanied by elevated capillary density. The results showed that dapagliflozin could promote angiogenesis after hindlimb ischemia. Then, the ischemic hindlimb adductor-muscle tissue samples from three rats of model group and dapagliflozin group were taken for phosphoproteomic testing. The results showed that the PI3K-Akt-eNOS signaling pathway was closely related to the effect of dapagliflozin on post-ischemic angiogenesis. Our study intended to verify this mechanism from the perspective of endothelial cells. In vitro, dapagliflozin enhanced the tube formation, migration, and proliferation of HUVECs under ischemic and hypoxic conditions. Additionally, the dapagliflozin administration upregulated the expression of angiogenic factors phosphorylated Akt (p-Akt) and phosphorylated endothelial nitric oxide synthase (p-eNOS), as well as vascular endothelial growth factor A (VEGFA), both in vivo and in vitro. These benefits could be blocked by either phosphoinositide 3-kinase (PI3K) or eNOS inhibitor. dapagliflozin could promote angiogenesis after ischemia. This effect might be achieved by promoting the activation of the PI3K-Akt-eNOS signaling pathway. This study provided a new perspective, new ideas, and a theoretical basis for the treatment of peripheral arterial disease.

Enrichment of Flavonoids in Short-Germinated Black Soybeans (Glycine max L.) Induced by Slight Acid Treatment.

Exogenous abiotic stimulant treatments are a straightforward and effective method for enhancing secondary metabolites in plants. In this study, the response surface optimization method was used to optimize the conditions for enriching flavonoids in short-germinated black soybeans under a slight acid treatment, and the mechanism of flavonoid accumulation during black soybean germination was explored. The results show that the use of a 126.2 mM citric acid-sodium citrate buffer (pH 5.10) as a slight acid treatment resulted in the highest flavonoid content when the black soybeans were germinated for 24 h. Under these conditions, the isoflavonoid (glycitin, daidzein, and genistein) increased significantly, and the flavonoid content reached 2.32 mg/g FW. The microacidified germination treatment significantly increased the activities and relative gene expression levels of key enzymes involved in flavonoid metabolism (4-coumarate-CoA ligase and cinnamic acid 4-hydroxylase, etc.). However, the slight acid treatment inhibited the growth of the black soybeans and caused damage to their cells. This was evidenced by significantly higher levels of malondialdehyde, superoxide anion, and hydrogen peroxide compared to the control group. Furthermore, the antioxidant system in the short-germinated soybeans was activated by the slight acid treatment, leading to a significant increase in the activities and relative gene expression levels of catalase and peroxidase. The results above show that a slight acid treatment was beneficial in inducing the accumulation of flavonoids during the growth of black soybean sprouts. This lays a technical foundation for producing black soybean products that are rich in flavonoids.

Transient Chemical Activation of Covalent Bonds for Healing of Kinetically Stable and Multifunctional Organohydrogels

Transient Chemical Activation of Covalent Bonds for Healing of Kinetically Stable and Multifunctional Organohydrogels

Mechanism study of the protective effects of selective cyclooxygenase-2 enzyme inhibitors on the liver of rats with type 2 diabetes mellitus combined with nonalcoholic steatohepatitis via Rho/ROCK pathway

Objective: To investigate whether the selective cyclooxygenase-2 enzyme inhibitors celecoxib has protective effect on the liver of rats with type 2 diabetes mellitus (T2DM) combined with nonalcoholic steatohepatitis (NASH) via inhibiting the expression of Rho/ROCK pathway. Methods: Forty male SD rats were randomly divided into four groups: type 2 diabetes mellitus combined with nonalcoholic steatohepatitis (T2DM-NASH) group, T2DM-NASH + celecoxib group, control group, and control+celecoxib group. The T2DM-NASH and T2DM-NASH + celecoxib groups were fed with high-sugar and fat diet, and the control group and control + celecoxib group were fed with basal diet (25 kJ/kg). Four weeks later, streptozotocin (STZ, 30 mg/kg) was intraperitoneally injected into the NASH group and T2DM-NASH + celecoxib group to induce T2DM model, and the control group and control + celecoxib group were intraperitoneally injected with isovolumic citric acid-sodium citrate buffer. Four weeks after STZ injection, the T2DM-NASH + celecoxib group and the control + celecoxib group were gavaged with celecoxib (10 mg·kg·d) dissolved in normal saline for 4 weeks, and the remaining two groups of rats were gavaged with isovolumic normal saline for 4 weeks. Animals were sacrificed at the end of the 12- weeks, and the liver tissue was collected. Liver pathological changes were observed by HE staining. The expressions of RhoA, RhoA, ROCK1 and ROCK2 proteins in liver were detected by immunohistochemistry and western blot. The expressional condition of RhoA, ROCK1 and ROCK2 mRNA in liver were detected by real-time quantitative PCR. The differences were compared between protein and mRNA expression among the groups by analysis of variance and t-test. Results: Compared with the control group and the control + celecoxib group, the liver tissue of the T2DM-NASH group and the T2DM-NASH + celecoxib group had severe steatosis, and there was partial inflammatory cell infiltration under the light microscope. The expression levels of RhoA, ROCK1 and ROCK2 protein and mRNA were significantly increased (P < 0.05) in each liver tissue, while liver steatosis was reduced to certain extent in T2DM-NASH + celecoxib group than T2DM-NASH group, and the expression levels of RhoA, ROCK1 and ROCK2 protein and mRNA were decreased in each liver tissue of T2DM-NASH group (P < 0.05). Conclusion: The selective cyclooxygenase-2 enzyme inhibitors celecoxib has a protective effect on the liver of rats with T2DM-NASH, and its effect may be achieved by inhibiting the expression of Rho/ROCK pathway.

The value of diffusion kurtosis imaging in early diagnosis of diabetic nephropathy model in Guangxi Bama mini pig

Objective To investigate the value of diffusion kurtosis imaging (DKI) in diagnosing early diabetic nephropathy. Methods Twelve pigs were divided into the experimental group (7 pigs) and the control group (5 pigs), used the random number table method. The experimental group was fed with high-fat high-sugar diet,and then repeatedly injected small doses (50 mg/kg) of Streptozotocin (STZ) through the ear vein. Meanwhile,the control group was fed with normal diet and injected with the same dose of citric acid-sodium citrate buffer solution.After the type 2 diabetes was established successfully, T1WI, T2WI and DKI sequence imaging were performed every month for 2 pigs from the experimental group and the control group,respectively.Mean kurtosis(MK), axial kurtosis (K∥), radial kurtosis (K⊥), fractional anisotropy (FA) and mean diffusivity(MD) were measured on the pseudo-color map of the post-processing workstation. fasting blood glucose(GLU),insulin (INS),renal function, urine routines and random albumin creatinine ratio(RACR) were measured before MRI scan. Specimens from bilateral kidneys were taken for pathological examination after MRI scan. The paired t test was used to compare the parameter values of the cortex and medulla.Independent sample t test was used tocompare the parameter values of the experimental group and the control group. Results In the experimental group,the MK, FA values of medulla were 0.66±0.07 and 0.19±0.04, the MK, FA values of cortex were 0.60±0.06 and 0.16±0.03.In the control group,the MK, FA values of medulla were 0.59±0.03 and 0.20±0.04, the MK, FA values of cortex were 0.53±0.03 and 0.17±0.04.The MK and FA values of medulla were increased compared with the cortex and the difference were statistically significant (P 0.05). Conclusion DKI sequencehas certain value in the diagnosis of early diabetic nephropathy,and to some extent reveals the pathological change in early diabetic nephropathy. Key words: Diabetic nephropathies; Magnetic resonance imaging; Disease models, animal

A simplified and miniaturized glucometer-based assay for the detection of β-glucosidase activity.

β-Glucosidase activity assays constitute an important indicator for the early diagnosis of neonatal necrotizing enterocolitis and qualitative changes in medicinal plants. The drawbacks of the existing methods are high consumption of both time and reagents, complexity in operation, and requirement of expensive instruments and highly trained personnel. The present study provides a simplified, highly selective, and miniaturized glucometer-based strategy for the detection of β-glucosidase activity. Single-factor experiments showed that optimum β-glucosidase activity was exhibited at 50 °C and pH 5.0 in a citric acid-sodium citrate buffer when reacting with 0.03 g/mL salicin for 30 min. The procedure for detection was simplified without the need of a chromogenic reaction. Validation of the analytical method demonstrated that the accuracy, precision, repeatability, stability, and durability were good. The linear ranges of β-glucosidase in a buffer solution and rat serum were 0.0873-1.5498 U/mL and 0.4076-2.9019 U/mL, respectively. The proposed method was free from interference from β-dextranase, snailase, β-galactosidase, hemicellulase, and glucuronic acid released by baicalin. This demonstrated that the proposed assay had a higher selectivity than the conventional dinitrosalicylic acid (DNS) assay because of the specificity for salicin and unique recognition of glucose by a personal glucose meter. Miniaturization of the method resulted in a microassay for β-glucosidase activity. The easy-to-operate method was successfully used to detect a series of β-glucosidases extracted from bitter almonds and cultured by Aspergillus niger. In addition, the simplified and miniaturized glucometer-based assay has potential application in the point-of-care testing of β-glucosidase in many fields, including medical diagnostics, food safety, and environmental monitoring.

Effect of Delta-like ligand 4 on pathological structure of retina in early diabetic rats and its relationship with vascular endothelial growth factor receptor-2

Objective To observe the effect of Delta-like ligand 4 (Dll-4) on the pathological structure of retina in early diabetic rats (DM) and its relationship with vascular endothelial growth receptor-2 (VEGFR-2). Methods A total of 70 male Sprague-Dawley rats were randomly divided into normal group and DM group, with 10 and 60 rats in each group, respectively. The rats of DM group was induced by intraperitoneal injection of streptozotocin to established DM model. The rats with blood glucose recovery and death were excluded, and the final 60 rats were included in the statistics. Rats in the normal group were injected with an equal volume of citric acid-sodium citrate buffer. Rats in the DM group were divided into DM 1 month (DM 1m) group, DM 2 months(DM 2m) group, DM 3 months (DM 3m) group and DM 3m + Anti group, DM 3m + phosphate buffer solution(PBS) group by random number table method, and 10 rats in each group. In the DM 3m+Anti group, 4 μl of anti- Dll-4 polyclonal antibody was injected into the vitreous cavity, and the antibody concentration was 0.25 mg/ml. The DM 3m+PBS group was intravitreally injected with an equal volume of PBS. Five days after the injection, the rats were sacrificed. Rats in the DM 3m group and the normal group were not treated, and were sacrificed 3 months after the model was established. The structure and microvascular changes of the retina were observed by hematoxylin-eosin staining, and the total thickness of the retina was measured. The expression of Dll-4 and VEGFR-2 in the retina was detected by immunohistochemistry and fluorescence quantitative polymerase chain reaction (PCR). One-way analysis of variance was used to compare the expression of Dll-4 and VEGFR-2 in the retina of each group. The least significant difference t test was used to compare the two groups. Results Light microscopy showed that the retinal ganglion cells layer in the DM 3m group were obviously edematous, the inner and outer nuclear layers were thinner, the number of cells was reduced, the arrangement was disordered, the edema of outer plexiform layer was obvious, and the microvessels were abnormally dilated. In the DM 3m+Anti group, the edema of outer plexiform layer was lessened than that of the DM 3m group, and the other layers were not significantly different from the DM 3m group. Compared with the normal group, the total retinal thickness of the DM 3m group, the DM 3m+Anti group and the DM 3m+PBS group increased (t=5.596, 3.290, 4.286; P=0.000, 0.008, 0.002). Immunohistochemical staining showed that a small amount of Dll4 was positively expressed in the retinal ganglion cell layer of the normal group; a small amount of VEGFR-2 was positively expressed in the ganglion cell layer and the inner and outer nuclear layers. The positive expression of Dll-4 and VEGFR-2 in retinal vascular endothelial cells of DM 3m group increased significantly. The expression of Dll-4 was significantly decreased in the retinal layers and vascular endothelial cells of DM 3m+Anti group, while the expression of VEGFR-2 was significantly increased. There was no significant difference between the positive expression of Dll4 and VEGFR-2 in the DM 3m+PBS group and the DM 3m group. The results of real-time PCR showed that the relative expression of Dll-4 and VEGFR-2 mRNA in the DM 3m group was significantly higher than that in the normal group (t=6.705, 20.871; P<0.05). Compared with DM 3m group, the relative expression of Dll-4 mRNA in DM 3m+Anti group decreased, and the relative expression of VEGFR-2 mRNA increased(t=2.681, 3.639;P<0.05). The relative expressions of Dll-4 and VEGFR-2 mRNA in the DM 3m+PBS group and DM 3m group were not statistically significant (t=0.513, 0.657; P<0.05). Conclusions The expression of Dll-4 in retinal vascular endothelial cells is gradually increased during the early retinopathy of DM rats. The expression of Dll-4 is inhibited, the expression of VEGFR-2 is up-regulated, and the plexus edema is alleviated. Key words: Diabetic retinopathy; Detal like 4; Vascular endothelial growth factor receptor 2

Effect of point-moxibustion on ghrelin and GHSR-1a expressions in lateral septal nucleus of rats with diabetic gastroparesis

To observe the effect of point-moxibustion on gastrointestinal motility, mRNA and protein expressions of ghrelin and growth hormone secretagogue receptor 1a (GHSR-1a) in lateral septal nucleus of rats with diabetic gastroparesis (DGP), and to investigate the central regulatory mechanism of DGP treatment with point-moxibustion. Forty SPF-grade Sprague-Dawley (SD) rats were randomly divided into a blank group, a model group, an electroacupuncture (EA) group and a point-moxibustion group, with 10 rats in each group. A DGP rat model was established by intraperitoneal injection of 2% streptozotocin (STZ) with 8-week irregular high-sugar and high-fat diet in the model group, the EA group and the point-moxibustion group; and rats in the blank group were injected intraperitoneally with 0.1 mmoL/L (pH 4.5) citric acid-sodium citrate buffer with 8-week normal diet. Eight weeks later, rats in the EA group were treated by EA at Zusanli (ST 36), Liangmen (ST 21) and Sanyinjiao (SP 6); while rats in the point-moxibustion group were treated by point-moxibustion at Zusanli (ST 36), Liangmen (ST 21) and Sanyinjiao (SP 6) for successive 15 d. Rats in the blank group and the model group were fixed as the control without intervention. After treatment, intestinal propulsion rate and gastric emptying rate were measured. The mRNA and protein expressions of ghrelin and GHSR-1a in the lateral septal nucleus were detected by real-time polymerase chain reaction (RT-PCR) and Western blot (WB). Compared with the blank group, the intestinal propulsion rate and gastric emptying rate of the model group were significantly lower (both P 0.05). Point-moxibustion at Zusanli (ST 36), Liangmen (ST 21) and Sanyinjiao (SP 6) can increase the intestinal propulsion rate and gastric emptying rate of DGP rats, and promote the mRNA and protein expressions of ghrelin and GHSR-1a in the central nervous system. The mechanism may be related to the activation of ghrelin pathway in hypothalamic arcuate nucleus-lateral septal nucleus.

Dissipation kinetics of oxytetracycline, tetracycline, and chlortetracycline residues in soil.

The dissipation of different residual states of tetracycline antibiotics (TCs) including oxytetracycline (OTC), tetracycline (TC), and chlortetracycline (CTC) laboratory microcosm systems was investigated in this study. The residues were fractionated by stepwise extractions into aqueous state (KCl solution extracts), organic state (MeOH extracts), residual state I (citric acid-sodium citrate buffer and ethyl acetate extracts) and residual state II (acetonitrile-EDTA-McIlvaine buffer extracts) for accurate evaluation of TCs pollution. The antibiotics in the aqueous state were hardly detected, whereas the antibiotics in the organic state dissipated relatively fast (not detectable within 15days after application) and followed simple first-order kinetics (SFOK) (R (2) from 0.929 to 0.990). While first-order double-exponential decay model (FODED) (R (2) from 0.840 to 0.999) and availability-adjusted first-order model (AAFO) (R (2) from 0.939 to 0.999) had a better fit on the dissipation of both residue state I and II than SFOK. TCs in these states were likely sequestered into a dormant undegradable phase since no degradation product was detected during the entire experiment. In addition, the overall 50% dissipation values (i.e., stability) of the three TCs were OTC > TC > CTC. The TCs tend to dissipate faster in the high water content and organic matter soil.

A simple, ultrasensitive sensor for gallic acid and uric acid based on gold microclusters/sulfonate functionalized graphene modified glassy carbon electrode

A facile and ultrasensitive sensor based on gold microclusters (AuMCs) electrodeposited on sulfonate functionalized graphene (SF-GR) was fabricated, and applied for the simultaneous determination of gallic acid (GA) and uric acid (UA). Taking advantage of the unique plane structure of the functionalized graphene (GR), the AuMCs were successfully electrodeposited on functionalized GR immobilized on the surface of a GCE. The results of scanning electron microscope (SEM) and energy spectrum analysis illustrated that AuMCs were deposited on the functionalized GR film. In comparison with the bare GCE, the pristine AuMCs and the pristine SF-GR modified electrode, AuMCs/SF-GR/GCE exhibited excellent electrochemical oxidation toward GA and UA. In addition, the two compounds were separated completely in 0.10M citric acid-sodium citrate buffer (pH 4.0) by differential pulse voltammetry (DPV) under optimum conditions. The anodic current was linearly related with 0.05–8.0μM GA and 0.2–50.0μM UA, with the detection limit of 10.7nM and 0.12μM, respectively. Furthermore, AuMCs/SF-GR/GCE was successfully applied to the independent determination of GA in black tea and Cortex moutan as well as the simultaneous determination of GA and UA in urine samples.

Simultaneous detection of metronidazole and chloramphenicol by differential pulse stripping voltammetry using a silver nanoparticles/sulfonate functionalized graphene modified glassy carbon electrode

A novel silver nanoparticles/sulfonated functionalized graphene modified glassy carbon electrode (AgNPs/SF-GR/GCE) was fabricated to determine chloramphenicol and metronidazole simultaneously. Taking advantage of sulfonic group, AgNPs were successfully electrodeposited on functionalized GR immobilized on the surface of a GCE. Scanning electron microscopy and energy spectrum analysis results confirmed that AgNPs were deposited on the functionalized GR film. Compared to the bare GCE or the pristine SF-GR modified electrode, AgNPs/SF-GR/GCE exhibited excellent electroreduction towards chloramphenicol and metronidazole. In addition, the two antibacterial drugs were separated completely in 0.10M citric acid-sodium citrate buffer (pH 4.0) by differential pulse stripping voltammetry under optimum conditions. The cathodic current was linearly related with 0.02∼20.0μM chloramphenicol and 0.10∼20.0μM metronidazole, with the detection limits of 0.01μM and 0.05μM respectively. Furthermore, AgNPs/SF-GR/GCE was applied to the simultaneous determination of chloramphenicol and metronidazole in an aquatic product.

Determination of total arsenic and arsenic(III) in phosphate fertilizers by hydride generation atomic absorption spectrometry after ultrasound-assisted extraction based on a control acid media.

An ultrasound-assisted extraction procedure was developed for determination of inorganic arsenic (As) in phosphate fertilizer by hydride generation atomic absorption spectrometry. The variables that affect the hydride generation step were optimized, including the reducer, acid, sample flow rate, and concentrations of the acid and reducer. The determination of As(lll) was performed through the simple control of solution pH with a 0.5 M citric acid-sodium citrate buffer solution at pH 4.5, and total As was determined after a pre-reduction reaction with 1.0% (w/v) thiourea. Ultrasound-assisted acid extraction was performed, and the parameters sonication time and acid and Triton X-114 concentrations were optimized using a 23 factorial design and central composite design. LODs for As(lll) and total As were 0.029 and 0.022 microg/L, respectively. The accuracy of the method was confirmed with certified reference materials. The method was successfully applied in the determination of inorganic As in phosphate fertilizer samples.

Study on Enzymatic Degradation of Cornstalk in Ionic Liquid

The influence of reaction conditions on the enzymatic degradation of cornstalk in the system of 1-ethyl-3-methylimidazolium acetate ([EMIM]OAc) was investigated. The optimum condition was as follows: 5 g 4 wt% cornstalk in ionic liquid solution, 3.64 mL pH 5 citric acid–sodium citrate buffer solution, the concentration of cornstalk 55 mg/mL, the ratio of enzyme and cornstalk 0.5 mL/g, reaction temperature 55 °C and reaction time 30 h. Under the optimum condition, the rate of enzymatic degradation was 96.6 %, and was 2.1 times quicker than under the conventional condition. The changes of the molecular structure of cornstalk dissolved in [EMIM]OAc were detected by FT-IR and SEM. It was also found that ionic liquid [EMIM]OAc had good reusability.

Role of mTOR in spinal cord in development of diabetic neuropathic pain in rats

Objective To evaluate the role of mTOR in spinal cord in the development of diabetic neuropathic pain in rats.Methods Sixty adult male Sprague-Dawley rats,aged 2 months,weighing 180-220 g,were used in the study.Forty-five rats among them were chosen randomly and diabetes mellitus was induced by intraperitoneal streptozotocin (STZ) 60 mg/kg and confirmed by blood glucose ＞ 16.7 mmol/L on day 3 after STZ injection.The left 15 rats received intraperitoneal injection of the equal volume of citric acid-sodium citrate buffer and served as normal control group (group C).Paw withdrawal threshold to von Frey filament stimulation was measured in the right hind paw before STZ injection and on 3,6,9,12,15,18,and 21 days after STZ injection.The diabetic rats with mechanical pain threshold decreasing by more than 50％ of the baseline were allocated to diabetic neuropathic pain group (group DP),and by less than 25 ％ of the baseline were allocated to diabetic non-neuropathic pain group (group NP).The rats were sacrificed at 21 days after STZ injection,and their lumbar enlargements of the spinal cord were removed for determination of the expression of mTOR and phosphorylated mTOR (p-mTOR) by Western blot.Results The expression of mTOR was significantly up-regulated in DP and NP groups when compared with group C (P ＜ 0.05),the expression of p-mTOR was up-regulated in DP group,and no significant change was found in the expression of p-mTOR in group NP (P ＞ 0.05).Compared with group NP,the expression of p-mTOR was significantly up-regulated (P ＜ 0.05),and no significant change was found in the expression of mTOR in group DP (P ＞ 0.05).Conclusion Activation of mTOR in the spinal cord is involved in the development of diabetic neuropathic pain in rats. Key words: Receptor-interacting protein serine-threonine kinases; Diabetic neuropathies

Preparation of Hydroxyapatite Coating by Using Citric Acid Sodium Citrate Buffer System in the Biomimetic Procedure

Abstract The present study has been aimed to investigate the preparation and analysis of calcium phosphate (CaP) based hydroxyapatite (HA, Ca10(PO4)6(OH)2) coatings formed on Ti6Al4V alloys in a new buffer environment. The coating process has been performed by means of biomimetic method. In the study, a synthetic body fluid (SBF), which is fully compatible with human blood plasma, has been prepared for the first time in the literature by using the citric acid – sodium citrate buffer system. Using this buffer system will not cause any toxic reactions in the human body. CaP coating of the Ti6Al4V surface has been performed in this new SBF. The surface roughness and thickness specifications of the coatings have been determined, their microstructures have been analyzed by using a scanning electron microscope (SEM), the elemental analysis (EDX) of the coating surfaces and the XRD analysis have been done. The results are presented and discussed.

Long-term effects of mild hyperglycemia exposure in utero and postnatal high fat diet on body weight and lipid metabolism in rat offsprings

To investigate the long-term effects of intrauterine mild hyperglycemia exposure and postnatal high fat diet on the body weight and metabolism of offspring through a pregnant rat model of intrauterine mild hyperglycemia. Twenty-one pregnant Wistar rats were randomly divided into intrauterine hyperglycemia group and control group. Twenty percent streptozotocin (STZ, 25 mg/kg)was given to rats of intrauterine hyperglycemia group by a single intraperitoneal injection to induce intrauterine mild hyperglycemia; control group rats received an equal volume of citric acid-sodium citrate buffer. Off springs were divided into 4 groups: exposed to intrauterine hyperglycemia and fed with normal diet group (group DN) or high fat diet group (group DF); exposed to intrauterine euglycemia and fed with normal diet group (group CN) or high fat diet group (group CF). The blood glucose levels of pregnant rats in two groups and body weights of offsprings in four groups were recorded. At the age of 28 weeks, the mesenteric fat amount, epididymal amount, perirenal fat amount, total triglyceride (TG) and high density 1ipoprotein-cholestrol (HDL-C) were measured in all four groups. (1)The average blood glucose level of intrauterine hyperglycemia group [(16.6 ± 3.4) mmol/L] was significantly higher than that of the control group [(5.8 ± 1.1) mmol/L, P < 0.01]. (2) On the birth day, 3 weeks and 4 weeks, the body weight of group DN[(7.4 ± 0.6), (44.1 ± 5.9), (79.6 ± 7.4) g] and group DF [(7.4 ± 0.2), (43.9 ± 6.9), (76.1 ± 5.8) g] were remarkably increased compared with group CN [(6.6 ± 0.5),(35.6 ± 4.4),(71.5 ± 6.8) g, P < 0.05]; but the body weight in group CF [(6.7 ± 0.5),(33.0 ± 6.5),(66.1 ± 10.2) g] had no statistical difference compared with group CN (P > 0.05). (3)From then on, the body weights of the offsprings in four groups presented an increasing trend, but there was no statistical difference until 28 weeks (P > 0.05). (4) The perirenal fat amount of group DN, group CF and group DF [(13.8 ± 3.3), (14.3 ± 3.2), (18.4 ± 1.3) g] were remarkably increased compared with group CN[(9.7 ± 3.5) g, P < 0.05]; the epididymal fat amount of group CF and group DF were also significantly increased compared to group CN (P < 0.05); the mesenteric fat amount in four groups had no statistical difference (P > 0.05). (5) The TG level of group DN, group CF and group DF [(0.52 ± 0.14), (0.52 ± 0.09), (0.54 ± 0.17) mmol/L] were significantly higher compared to group CN [(0.41 ± 0.09) mmol/L, P < 0.05], but there was no statistical difference within the first three groups (P > 0.05); the HDL-C level in four groups had no statistical difference (P > 0.05). In intrauterine mild hyperglycemia environment, there were some evidently metabolic changes observed in the offspring, including body weight increasing on birth day and early postnatal period, visceral fat amount increasing and lipid metabolism disorders, which could be aggravated by postnatal high fat diet.

Onopordum acanthium L. (Asteraceae) flowers as coagulating agent for cheesemaking

By trituration in liquid nitrogen, homogenization in 0.1 mol/L citric acid–sodium citrate buffer (pH 3.0) containing 1.0 mmol/L EDTA, and centrifugation (10000 × g) of fresh Onopordum acanthium L. (Asteraceae) flowers, a proteolytic preparation (“onopordosin”) was obtained (pI 4.4), which showed proteolytic and clotting activity (0.546 ± 0.004 Rennet Units/g flowers and 0.090 ± 0.003 Endopeptidase Units/g flowers, respectively) at acid pH values, conditions that favor its use in cheese manufacturing. Hydrolytic behavior (SDS-Tricine PAGE) of onopordosin was compared with that of chymosin in bovine milk clotting assays. Onopordosin was used as vegetal coagulant with pasteurized bovine milk to manufacture a semi-hard type cheese which was analyzed by sensory panelists at the Experimental Superior Institute of Food Technology in Argentina, who evaluated different parameters and concluded that the quality of the cheese made with onopordosin was similar to that of commercial cheeses.

High-performance liquid chromatography with post-column 2,2′-diphenyl-1-picrylhydrazyl radical scavenging assay: Methodological considerations and application to complex samples

An improved post-column 2,2′-diphenyl-1-picrylhydrazyl (DPPH ) radical scavenging assay for the screening of antioxidants in complex matrices was developed. Experimental parameters believed to be influential to DPPH response were studied in a univariate approach. Optimum conditions were found to be: 5 × 10 −5 M DPPH reagent prepared in a 75% methanol: 25% 40 mM citric acid–sodium citrate buffer (pH 6) solution, degassed with nitrogen; reaction coil of 2 m × 0.25 mm i.d. PEEK tubing; detection at 521 nm; analysis at room temperature. The analytical utility of this protocol was evaluated by screening for antioxidants in thyme and green tea, in comparison with two commonly employed methodologies.

Determination of Co 2+ based on the cobalt(II)-catalyzed electrochemiluminescence of luminol in acidic solution

In this paper, the electrochemical behavior of luminol in weakly acidic solution was studied. It is found that Co 2+ remarkably enhances the electrochemiluminescence (ECL) of luminol in citric acid–sodium citrate buffer solution (pH = 4.0) when a pulse potential (−1.8 to +1.0 V, versus Ag/AgCl) is applied to the Pt electrode. The selectivity for Co 2+ is very good because most of the other water-soluble metal ions do not interfere. A sensitive and selective ECL method for determination of Co 2+ is proposed. After optimization of the reaction conditions and electrochemical parameters influencing the relative ECL intensity, the linear range responding to Co 2+ is 5.0 × 10 −12 to 1.0 × 10 −7 mol/L, and the detection limit is 2.0 × 10 −12 mol/L. The relative standard deviation for 5.0 × 10 −10 mol/L cobalt(II) is 3.7% ( n = 11).

Flow-through spectrophotometric sensor for the determination of saccharin in low-calorie products

A simple, rapid and inexpensive monoparameter flow-through sensor has been developed for the determination of saccharin in low calorie and dietary products. The method is based on the transient adsorption of the sweetener on Sephadex G-25 solid phase packed to a height of 20 mm in the flow cell. The optimal transient retention of the synthetic sweetener, in terms of sensitivity and sampling frequency, was obtained when pH 2.75 citric acid-sodium citrate buffer 5 × 10−3 M was used as a carrier at a flow-rate of 1.5 ml min−1. Saccharin was determined measuring its intrinsic absorbance at 217 nm at its residence time. Calibration graphs for peak height and peak area were linear over the range 5.0–200.0 μg ml−1, RSD 1.18%, and 1.0–200.0 μg ml−1, RSD 0.78%, respectively. Saccharin was determined in several food samples measuring height or area peak, obtaining recoveries ranging between 98–104 and 99–102% for height and area peak, respectively. The procedure was validated for use in the determination of saccharin in low calorie and dietary products giving reproducible and accurate results.