Inhibitory effect of voglibose and gymnemic acid on maltose absorption in vivo

AIM: To determine whether diabetic care can be improved by combination of voglibose and gymnemic acid (GA), we compared the combinative and individual effects of voglibose and GA on maltose absorption in small intestine. METHODS: The small intestine 30 cm long from 2 cm caudal ward Treitz's ligament of Wistar rat was used as an in situ loop, which was randomly perfused in recircular mode with maltose (10mmol/L) with or without different dosages of voglibose and/or GA for an hour. To compare the time course, perfusion of 10 mmol/L maltose was repeated four times. Each time continued for 1 hour and separated by 30 minutes rinse. In the first time, lower dosages of GA (0.5g/L) and/or voglibose (2 micromol/L) were contained except control. RESULTS: Absorptive rate of maltose was the lowest in combinative group (P【0.05, ANOVA), for example, the inhibition rate was about 37% during the first hour when 0.5 g/L-GA and 2 micromol/L voglibose with 10 mmol/L maltose were perfused in the loop. The onset time was shortened to 30 minutes and the effective duration was prolonged to 4 hours with the combination; therefore the total amount of maltose absorption during the effective duration was inhibited more significantly than that in the individual administration (P 【 0.05, U test of Mann Whitney). The effect of GA on absorptive barriers of the intestine played an important role in the combinative effects. CONCLUSION: There are augmented effects of voglibose and GA. The management of diabetes mellitus can be improved by employing the combination.

Inhibitory effect and mechanism of acarbose combined with gymnemic acid on maltose absorption in rat intestine

AIM: To compare the combinative and individual effect of acarbose and gymnemic acid (GA) on maltose absorption and hydrolysis in small intestine to determine whether nutrient control in diabetic care can be improved by combination of them. METHODS: The absorption and hydrolysis of maltose were studied by cyclic perfusion of intestinal loops in situ and motility of the intestine was recorded with the intestinal ring in vitro using Wistar rats. RESULTS: The total inhibitory rate of maltose absorption was improved by the combination of GA (0.1g/L-1.0 g/L) and acarbose (0.1 mmol/L-2.0 mmol/L) throughout their effective duration (P 【0.05, U test of Mann-Whitney), although the improvement only could be seen at a low dosage during the first hour. With the combination, inhibitory duration of acarbose on maltose absorption was prolonged to 3h and the inhibitory effect onset of GA was fastened to 15 min. GA suppressed the intestinal mobility with a good correlation (r = 0.98) to the inhibitory effect of GA on maltose absorption and the inhibitory effect of 2 mmol/L (high dose) acarbose on maltose hydrolysis was dual modulated by 1g/L GA in vivo indicating that the combined effects involved the functional alteration of intestinal barriers. CONCLUSION: There are augmented effects of acarbose and GA,which involve pre-cellular and paracellular barriers. Diabetic care can be improved by employing the combination.

Effect of Maltose Concentration on Plant Regeneration of Anther Culture with Different Genotypes in Rice (<i>Oryza sativa </i>L.)

This study describes the impact of different concentrations of maltose on plant regeneration of anther culture for five genotypes of rice (Oryza sativa). N6 medium was used for calli induction, while N6 medium supplemented with different concentrations of maltose, 2.0 mg/L NAA and 0.5 mg/L kinase was used for plant regeneration. The result showed that during the initial stages of calli induction the anther cultures had varying rates of calli formation among genotypes, with the best frequency being observed for Dreami2/CaMsrB2-8-DH-1 with a calli frequency of 27.8%. Different genotypes of rice cultured in regeneration media showed varying plantlet regeneration on media supplemented with different concentrations of maltose, with low concentrations (0.04 g/L) leading to low frequency regeneration plantlet but high green plant production. Indeed, when Dreami2/CaMsrB2-8-DH-2 and Dreami2/CaMsrB2-8-DH-5 were cultivated under these conditions, 100% green plants were observed. Another genotype also showed a small rate of albino frequency in response to the lowest concentration of maltose, while increased maltose concentrations resulted in increased rates of albino plants. Overall, the results of this study should facilitate establishment of an efficient plant regeneration system from anther culture in rice.

Maltose Concentration by Ultrafiltration

[Objective] The aim was to study on effect of maltose concentration by ultrafiltration.[Method] 40% and 15% maltose syrups were concentrated using ultrafiltration membranes at molecular weight of 6 000 Da in order to study on concentration effect of maltose and restoration effect of membranes property through backflushing.[Result] When 40% maltose was concentrated with the membrane,membrane flux weakened rapidly and pores blocked.In contrast,when 15% maltose was concentrated with the same membrane,the membrane flux was high and weakened very slowly.Dextrose equivalent(DE) and luminousness changed from 43% and 91%T before filtration to 50% and 98%T after filtration,respectively.[Conclusion] The research provides a practical method to improve transparency of maltose products and extend quality guarantee period.

Biosensor for maltose quantification and estimation of maltase activity

Abstract: The aim of this study was to create a laboratory model of an amperometric microbial biosensor for maltose quantification in the presence and absence of starch and to estimate the use of the model in the study of maltase activity of the culture-receptor. The biosensor for maltose was developed on the basis of a Clark-type oxygen electrode, coupled with a bioreceptor, which contained bacterial cells immobilized on the membrane. The determination of maltose concentration was based on measuring the rate of electrode current change in response to addition of the analyte. The detection limit of the biosensor was 1 μM maltose, a linear interval of standard curve was observed from 14 μM up to 1.9 mM of maltose. The microbial biosensor demonstrated good sensitivity to maltose, 36.02 nA (M-s)-1. Combination of bioreceptors on the basis of fungus and bacterium allowed of using the biosensor for quantification of maltose in the presence of starch. Changes in metabolism of the culture-receptor had an effect on the biosensor response. It indicated that the developed model was a tool of simple construction and easy-to-use in the study of maltase activity of the immobilized culture-receptor.

Optimization of Fermentation Conditions of <i>Bacillus thuringiensis</i>EC1 for Enhanced Methionine Production

Bacillus thuringiensis EC1, isolated from the fermented oil bean seed, Pentachletra macrophila Benthan, produced a methionine yield of 1.89 mg/ml. The influence of cultural conditions on methionine accumulation by B. thuringiensis EC1 showed that a 20% medium/fermenter volume ratio and a 5% inoculum size increased methionine yield. The carbon of choice was maltose and at 8% level stimulated methionine production. Among the nitrogen sources studied, ammonium sulphate was found to be the best and at 1% concentration produced a methionine yield of 2.56 mg/ml. All growth-promoting substances and their mixtures enhanced methionine accumulation by B. thuringiensis EC1. The effect of Vitamins on methionine production showed that riboflavin and thiamine HCl at 1.0 μg/ml yielded 2.49 mg/ml and 2.80 mg/ml methionine respectively. The influence of bivalent metals on methionine accumulation indicated that Zn2+ at all concentration stimulated methionine production. Mg2+ and Ba2+ at 0.1 μg/ml and 10.0 μg/ml respectively improved methionine yield. Optimizing the cultural conditions of B. thuringiensis EC1 in submerged medium gave a methionine yield of 3.18 mg/ml.

Sweet Potato Leaf Curl Virus: Coat Protein Gene Expression in <i>Escherichia coli</i>and Product Identification by Mass Spectrometry

Sweet potato is one of the first natural GMOs, genetically modified 8000 years ago by Agrobacterium rhizogenes as reported recently by Kyndt et al. A section of 10 kbp long DNA (Transferred- DNA or T-DNA) of the Ri (Root-inducing) plasmid was transferred to the plant genome by A. rhizo-genes and has been maintained in all 291 hexaploid sweet potato cultivars of the world. The maintenance in the sweet potato genome and expression of two T-DNA genes for tryptophan-2-monooxygenease (iaaM) and for indole-3-acetamide hydrolase (iaaH) are likely to be physiologically significant since these enzymes convert tryptophan to indole-3-acetic acid, a major plant growth hormone auxin. Sweet potato (Ipomoea batatas (L.) Lam) is ranked the third most important root crop after potato and cassava, and the seventh in global food crop production with more than 126 million metric tons. Although sweet potato originated in Central or South America, China currently produces over 86% of world production with 109 million metric tons. In the United States, North Carolina is the leading producer with 38.5% of the 2007 sweet potato production, followed by California, Mississippi, and Louisiana with 23%, 19%, and 15.9%, respectively. Leaf curl virus diseases have been reported in sweet potato throughout the world. One of the causal agents is Sweet potato leaf curl virus (SPLCV) belonging to the genus Begomovirus (family Geminiviridae). Although SPLCV does not cause symptoms on Beauregard, one of the most predominant sweet potato cultivars in the US, it can reduce the yield up to 26%. Serological detection of SPLCV is not currently available due to the difficulties in obtaining purified virions that can be used as antigen for antiserum production. In attempts to obtain the coat protein (CP) of SPLCV for antibody production, primers were designed to amplify the CP gene. This gene was cloned into the expression vector pMAL-c2E as a fusion protein with maltose-binding protein, and transformed into Escherichia coli strain XL1-Blue. After gene induction, a fusion protein of 72 kDa was purified by amylose affinity chromatography. The yield of the purified fusion protein was approximately 200 μg/liter of bacterial culture. Digestion with enterokinase cleaved the fusion protein into a 42.5 kDa maltosebinding protein and a 29.4 kDa protein. The latter protein was identified by mass spectrometry analysis as the coat protein of SPLCV based on the fact that the mass spectrometry elucidated the sequences corresponding to 37% of amino acid positions of the SPLCV coat protein.

Relation between Gastrointestinal Adverse Effects in Gaucher Disease Patients and Intestinal Disaccharidases Activity Evaluated by Methane Hydrogen Breath Test

The aim of this paper is to study the disaccharidase profile in GD （Gaucher disease） patients treated or not with miglustat and compare it with a healthy control group. Miglustat is an iminosugar used as substrate inhibitor in the therapy of some lysosomal disorders, its main side effects resembling carbohydrate maldigestion symptoms and cause more than 50% of medication discontinuation among GD patients. In-vitro studies have revealed that miglustat can act as an inhibitor of some digestive enzymes. An exploratory non-interventional study was designed to compare the disaccharidase profile assessed by MHBT （methane hydrogen breath test） and to analyze the correlation with the reported gastrointestinal symptoms in GD patients （40） and healthy subjects （20）. MHBT was performed following the ingestion of lactose, sucrose and maltose on different days. Each participant completed two detailed surveys about dietary habits, medications and gastrointestinal symptoms previous and during the test. Twenty-one GD were receiving miglustat, 10 （47.6%） of them reported gastrointestinal side effects, and 7/10 （70%） recorded a positive MHBT （lactose 5, maltose 2, and sucrose 1）. In 6/19 （31.6%） patients that never been exposed to miglustat and 7/20 （35%） controls a positive MHBT were detected. The comparison of the malabsorption phenotype between GD patients exposed and not exposed to miglustat （p = 0.028） and control group （p 〈 0.04） showed high statistical significance for the group of patients treated with miglustat. These results suggest that miglustat therapy induces persistent changes in digestive enzyme activity in GD patients.