Changes In Α-amylase Activity Research Articles

Modelling of icodextrin hydrolysis and kinetics during peritoneal dialysis

In peritoneal dialysis, ultrafiltration is achieved by adding an osmotic agent into the dialysis fluid. During an exchange with icodextrin-based solution, polysaccharide chains are degraded by α-amylase activity in dialysate, influencing its osmotic properties. We modelled water and solute removal taking into account degradation by α-amylase and absorption of icodextrin from the peritoneal cavity. Data from 16 h dwells with icodextrin-based solution in 11 patients (3 icodextrin-exposed, 8 icodextrin-naïve at the start of the study) on dialysate volume, dialysate concentrations of glucose, urea, creatinine and α-amylase, and dialysate and blood concentrations of seven molecular weight fractions of icodextrin were analysed. The three-pore model was extended to describe hydrolysis of icodextrin by α-amylase. The extended model accurately predicted kinetics of ultrafiltration, small solutes and icodextrin fractions in dialysate, indicating differences in degradation kinetics between icodextrin-naïve and icodextrin-exposed patients. In addition, the model provided information on the patterns of icodextrin degradation caused by α-amylase. Modelling of icodextrin kinetics using an extended three-pore model that takes into account absorption of icodextrin and changes in α-amylase activity in the dialysate provided accurate description of peritoneal transport and information on patterns of icodextrin hydrolysis during long icodextrin dwells.

Effect of static magnetic field treatment on the germination of brown rice: Changes in α-amylase activity and structural and functional properties in starch

The study aimed to explore the stimulating effect of static magnetic field (SMF) treatment on germinated brown rice (GBR) by monitoring changes in α-amylase activity and structural and functional properties of starch. Brown rice was exposed to SMF (10 mT, 60 min, 25 °C) and then germinated for 0 h −72 h at 30 °C. Compared with the control, SMF treatment improved α-amylase activity (15.2%), leading to the hydrolysis of starch into reducing sugar (8.2%) and increasing the germination rate (9.7% −158.8%), shoot length (9.1% −87.3%), root length (19.2% −110.0%), and fresh weight (0.9% −16.5%). In view of the properties of starch, SMF treatment also altered the surface microstructure, induced partial losses of birefringence, exerted no significant effect on the crystalline type, slightly increased the gelatinization temperatures, and significantly decreased the peak viscosity. This study suggested that SMF could serve as a prospective technique for GBR products processing.

BIOFLAVONOIDS AS AGENTS FOR CORRECTING NITRO-OXIDATIVE STRESS AND SALIVARY GLAND FUNCTIONS IN RATS EXPOSED TO ALCOHOL DURING MODELED LIPOPOLYSACCHARIDE-INDUCED SYSTEMIC INFLAMMATORY RESPONSE

The aim: To investigate the effects of bioflavonoids (curcumin, epigallocatechin-3-gallate and quercetin) on nitro-oxidative stress and the functions of submandibular SGs in rats under alcohol exposure during SIR. Materials and methods: The studies were conducted on 35 rats of the Wistar line weighing 205-220 g, divided into 5 groups of seven animals in each: the 1st group, control group I, included animals receiving isotonic sodium chloride solution intragastrically twice a day; the 2nd group, control group II, included rats exposed to alcohol (in a dose of 24 mg/kg intragastrically through gavage a twice a day) for last 2 weeks during lipopolysaccharide (LPS)-induced SIR; the rats of the 3rd, 4th and 5th groups exposed to alcohol during LPS-induced SIR, which also received bioflavonoids. The bioflavonoids (“Sigma-Aldrich, Inc.”, USA) were as following: curcumin (in a daily dose of 200 mg/kg), epigallocatechin-3-gallate (in a daily dose of 40 mg/kg), and quercetin (in a daily dose of 200 mg/kg), respectively. SIR was induced by intraperitoneal administration of Salmonella typhi LPS (during the first week a dose of 0.4 μg/kg of body weight was administered 3 times a week; during the next 7 weeks of the experiment rats received 0.4 μg/kg of body weight once a week. The formation of superoxide anion radical (О2 -), activity of NO-synthase – total (NOS), its constitutive and inducible isoforms (cNOS, iNOS), and concentration of peroxynitrites and S-nitrosothiols were evaluated spectrophotometrically. To assess the functional status of submandibular SGs in their homogenate we determined α-amylase activity (spectrophotometrically) and the aquaporin-5 concentration (by enzyme-linked immunosorbent assay). through gav-age with orogastric cannul. Results: When applying bioflavonoids under the conditions of alcohol administration during SIR, NADH-induced .О2 - production decreased and yielded to the result in the control group II by 36.8% under administering curcumin, by 34.5% under administering epigallocatechin-3-gallate, and by 41.3% under administering quercetin. The total NOS activity in SGs tissues was inferior by 42.8% to the relevant data in the control group II (under curcumin administration), by 33.7% (under epigallocatechin-3-gallate administration) and by 46.6% (under quercetin administration); and the iNOS activity decreased by 47.0, 38.3 and 52.0%, respectively. Under the administration of bioflavonoids peroxynitrites concentration in the submandibular SGs tissues was inferior to the control group II by 35.6% (under curcumin administration), by 37.4% (under epigallocatechin-3-gallate administration), and by 39.3% (under quercetin administration); the content of S-nitrosothiols was lower by 34.5, 31.1 and 35.3%, respectively. The administration of bioflavonoids led to the changes in α-amylase activity in the submandibular SGs tissues: its values exceeded the relevant data in the control group II by 40.4% (under curcumin administration), by 38.2% (under epigallocatechin-3-gallate administration), and by 34.1% (under quercetin administration); under those conditions aquaporin-5 concentration grew in 2.66, 2.61 and 2.55 times, respectively. Conclusions: The use of bioflavonoids (curcumin, epigallocatechin-3-gallate, and quercetin) under the combined administration of 40% ethanol solution and LPS considerably limits the development of nitro-oxidative stress in the tissues of the submandibular SGs. The administration of the bioflavonoids increases the level of cNOS coupling, and improves the functional status of the submandibular SGs under the combined administration of alcohol and LPS enhancing the activity of α-amylase and concentration of aquaporin-5.

Changes in sugar and starch concentrations in parsnip (Pastinaca sativa L.) during root growth and development and in cold storage

SummaryLow-temperature sweetening of parsnip (Pastinaca sativa L.) roots, which may occur both pre-harvest and post-harvest, is a well-known phenomenon, but is poorly understood. ‘White King’ parsnip roots were analysed over two seasons (2008 and 2009) during field growth and over six months cold storage at 1ºC for their dry matter content, as well as their starch, sucrose, glucose, fructose, and malto-oligosaccharide (MOS) concentrations and for their changes in amylolytic enzyme activities (2009 only). In 2008, when the air temperature fell below 5ºC for 12 d in the last 8 weeks before harvest, the concentration of starch decreased significantly (P ≤ 0.05) and the concentration of total sugar increased significantly. In 2009, when temperatures did not fall below 5°C during the last 8 weeks before harvest, the concentrations of starch (339 + 17 mg g–1 DW) and total sugars (168 + 12 mg g–1 DW) did not change significantly. However, in both years, during 24 weeks in cold storage at 1ºC, starch levels were almost completely depleted, whereas sucrose concentrations and, to a lesser extent, MOS concentrations increased at least two-fold. Glucose and fructose concentrations also increased significantly during 24 weeks in cold storage, but to a much lower level than sucrose or MOS. Total amylolytic activity and α-amylase activity doubled during the first 8 weeks in cold storage, whereas β-amylase activity did not change significantly. As products of α-amylase activity, changes in MOS concentration paralleled the changes in α-amylase activity. The accumulation of sucrose and MOS may raise the culinary quality of cold-stored parsnip.

Inflexibly Focused under Stress: Acute Psychosocial Stress Increases Shielding of Action Goals at the Expense of Reduced Cognitive Flexibility with Increasing Time Lag to the Stressor

Dynamically adjusting the right amount of goal shielding to varying situational demands is associated with the flexibility of cognitive control, typically linked with pFC functioning. Although stress hormones are found to also bind to prefrontal receptors, the link between stress and cognitive control remains elusive. Based on that, we aimed at investigating effects of acute psychosocial stress on dynamic control adjustments. Forty-eight healthy volunteers were exposed to either a well-established stress induction protocol (the Trier Social Stress Test, TSST) or a standardized control situation before a selective attention (Simon) task involving response conflicts. The individual physiological stress response was monitored by analyzing levels of free cortisol and α-amylase activity in saliva samples showing that the TSST reliably induced an increase of endogenous stress hormone levels. Acute stress did not inevitably impair cognitive functioning, however, as stressed participants showed tonically increased goal shielding (to reduce interference) at the expense of decreased cognitive flexibility. Importantly, as a novel finding in humans, stress effects on cognitive functions were not present immediately after the stress experience but developed gradually over time and, therefore, paralleled the time course of the hypothalamus-pituitary-adrenal (HPA) stress response. In addition, the total increase of individual cortisol levels reflecting HPA activity, but not the total changes in α-amylase activity associated with sympathetic activity, was reversely related to the amount of cognitive flexibility in the final block of testing. Our study provides evidence for a stress-induced time-dependent decrease of cognitive flexibility that might be related to changes in cortisol levels.

Salinity Induced Changes in α-Amylase Activity During Germination and Early Cotton Seedling Growth

Salinity induced changes in α-amylase activity in three cotton cultivars (NIAB-Karishma, NIAB-86 and K-115) was studied during germination and early seedling growth under controlled conditions. The increase in NaCl concentration resulted in the decrease in α-amylase activity and break down of starch into reducing and non-reducing sugars in all cultivars, however, it was more pronounced in NIAB-86. K-115 showed highest germination followed by NIAB-Karishma and NIAB-86.

Light effects on α-amylase activity and carbohydrate content in relation to lipid mobilization during the seedling growth of sunflower

The changes in α-amylase activity and in starch and free sugar content were investigated in correlation with lipid mobilization inHelianthus annuus during the first 15 days of seedling growth in discontinuous light and in darkness. Throughout the seedling development α-amylase activity increased more significantly in light than in darkness. It was always lower in cotyledons than in other tissues of the embryo axis. In both culture conditions, most of the transitory carbohydrates accumulated in germinating cotyledons were very likely synthesized by gluconeogenesis from the stored lipid breakdown. Nevertheless, in light-grown cotyledons, photosynthesis contributes to increase the carbohydrate levels. The study of several soluble sugars indicates that 1) sucrose stored in cotyledons of mature seeds was used at the onset of seedling growth, more rapidly in light than in darkness, 2) galactose and xylose, both involved as precursors of some cell-wall polysaccharides, remained at a very low level throughout the 15 days and 3) glucose, fructose and maltose accumulated in old etiolated cotyledons in contrast to what occurred in the light.

Changes in α-amylase activity during plant regeneration from rice calli

Summary Changes in α-amylase activity in rice calli during organogenesis were investigated in 5 rice varieties that exhibit different abilities for plant regeneration. During organ differentiation in rice callus tissues, samples were taken at 5-day intervals up to 35 days and α-amylase (EC. 3.2.1.1) activities were measured. The activity in regenerative calli began to increase 15 to 20 days after transfer to the regeneration medium and were elevated 7–11 fold during the culture period, while the calli transferred to callus maintenance medium did not increase and maintained a stable state. The increase in α-amylase activity in regenerative calli was more rapid in the calli that showed higher regenerative abilities (Sasanishiki, Tadukan and Tetep) than in the calli that showed lower regenerative abilities (Fujisaka 5 and Nipponbare). Correlation coefficients between frequencies of organ differentiation and α-amylase activity in the calli 35 days after transfer to the regeneration medium was highly significant. Expression of a rice α-amylase gene ( RAmylA ) in callus tissues during organ differentiation was examined by Northern blot and Western blot analyses. Messenger RNA from the RAmylA gene, which is a main transcript in germinating rice seeds, was highly expressed in the regenerating calli 15 days after transfer. The translated product from the mRNA of the RAmylA gene and α-amylase isozyme band I (1A and 1B) were highly expressed 20 days after transfer, especially in the regeneration medium.

Characteristics and Varietal Differences of α-Amylase Isozymes in Rice Callus Tissues

The characterization and varietal differences of α-amylase isozymes in rice callus tissues were studied by disc electrophoresis and gel electricfocusing on polyacrylamide gel electrophoresis (isoelectricfocusing). (1) Amylase in callus tissues grown on a Maeda's chemical defined medium containing 10-5M 2, 4-D was resolved into six isozymes by disc electrophoresis and ten by isoelectricfocusing. From the investigations on heat (70°C, 15 min.) stability, Ca2+ -requirement and EDTA (5 × 10-3M)resistancy of ten isozymes by isoelectricfocusing, we found that all of these isozymes were α-amylase, and only one isozyme (band a), which was fastest-migrating and most acidic, was a new rice o'-amylase that was not required Ca2+ and not inactivated by EDTA. (2) Some biochemical changes in Aichi asahi callus tissues grown in the 10-5M 2, 4-D medium containing various carbon sourses (glucose, fructose, maltose, lactose, xylose, galactose, arabinose and soluble starch) which were added in place of sucrose, were investigated. The growth, α-amylase isozyme patterns and protein content in callus tissues grown in soluble starch were not different from sucrose medium. In all sugars, as only arabinose did not allow the callus growth, it was suggested that this sugar was inappropriate as carbon sourse. The banding patterns of α-amylase isozymes in arabinose medium were different from other sugars, that is, amylase "g" was strongly inhibited. (3) α-Amylase isozyme banding patterns in callus tissues of three normal varieties (Ginbozu, Aichi asahi, Te-Tep) and three dwarf varieties (Tan ginbozu, Waisei shinriki, Kotake tamanishiki), which were studied by isoelectricfocusing, were different from each others and these isozyme activities were changed in compliance with total α-amylase activity. α-Amylase activity in Tan ginbozu callus tissus was lowest in six varieties, but this callus tissus contains ten isozymes. Hence, this dwarfism is not elucidated by changes in isozyme banding patterns. (4) Changes in α-amylase activity and its isozymes in rice variety, Fujiminori and its four strains (Reimei, 71, 71L, and 71S) derived by 60Co-irradiation were studied. The callus tissue of strain "71", which showed the low plant height and was thus dwarf mutant, represented poor growth, low protein content and low enzyme activity. Beside, each activity of ten α-amylase isozymes were relatively low. The callus tissue of strain "71S", which showed the lowest plant height, represented the same biochemical changes as ones of Fujiminori.

Inhibition of Gibberellic Acid Induced α-Amylase Formation by Fluorine Substituted Phenoxy Compounds

Summary A study has been made of changes in α-amylase activity in germinating seeds of Cyamopsis tetragonoloba . Orthofluorophenoxy-α-methyl acetic acid and N-benzylorthofluorophenoxy acetamide inhibited growth and α-amylase activity in cotyledons and seedling axes of treated seeds. Gibberellic acid increased the biosynthsis of α-amylase resulting in its enhanced activity. When seeds were treated with fluorine substituted phenoxy compounds and gibberellic acid simultaneously, the enhanced synthesis of α-amylase due to latter was reversed by the former.