The dynamics of proteinases activity in fish chyme and intestine mucosa upon exposure to fresh and brackish water in vitro

The dynamics of activities of proteinases in roach and perch chyme and in bream intestine mucosa upon exposure to water with various salinities for 96-216 h were studied. Irrespective of the water salinity and source of the enzymes, the proteolytic activities in chyme and intestine mucosa may rise considerably during exposure. This rise is presumably provided by the intestine microflora. This noted phenomenon is least typical for the ichthyophage-facultative benthophage perch when compared to typical benthophages. This is most likely determined by the lower species diversity of the enteral microbiota in perch.     

Fungal flora of Egyptian baladi bread with special reference to the mutagenic effects of their toxic metabolites

The fungal flora of wheat flour and baladi bread in upper Egypt were investigated. Most of the isolated fungal species belong to the genus Aspergillus. The presence of non heat resistant fungi of the both flat surfaces of baladi bread, came from contamination after baking and from improper handling at homes. Among the heat resistant fungi, A. fumigatus and A. niger, were recorded to inhabit the spongy crumb although the high temperature of baking process which reached approximately 100 ° C in the center of the bread.The mutagenic effects of the fungal metabolites of the extract of mouldy bread was investigated. Several kinds of aberrations were observed in all stages of mitotic division. The most interesting effect of these fungal metabolites were the induction of tripolar and quadripolar spindle. Multinucleate and polyploid cells were also observed under relatively high concentrations. It was noticed that at either higher concentrations or lower concentrations with long exposure, damaged cells were observed. The hazards involved through the consumption of individuals to such mouldy bread, is accumulation of possible deleterious effects from both long and short term exposure to these toxic metabolites.     

Serotonin-producing enterochromaffin (EC) cells of gastrointestinal mucosa in dexamethasone-treated rats

The aim of our study was to investigate the morphological, immunohistochemical and ultrastructural changes of rat serotonin-producing enterochromaffin (EC) cells of gastrointestinal mucosa in dexamethasone-treated rats (D). After 12-daily intraperitoneal administration of 2 mg/kg dexamethasone, rats developed diabetes similar to human diabetes type 2. Stomach, small and large intestines were examined. Large serotonin positive EC cells appeared in the corpus mucosa epithelium of D group of rats, although these cells were not present in control (C) rats. Both volume fraction and the number of EC cells per mm(2) of mucosa were significantly increased only in the duodenum. However, the number of EC cells per circular sections of both antrum and small intestine was increased, but reduced both in the ascending and descending colon in D group. The dexamethasone treatment caused a strong reduction in number of granules in the antral EC cells, while it was gradually increased beginning from the jejunum to descending colon. The mean granular content was reduced in the antral EC cells but increased in the jejunal EC cells in D group. In conclusion, the present study showed that morphological changes in gut serotonin-producing EC cells occurred in diabetic rats.     

草鱼肠道酸碱度的研究

胃肠道是一个复杂的消化系统, 每一部分都具有独特的生理特征。酸碱度(pH)是消化道重要的生理指标之一, 其对营养物质的消化、吸收和肠道微生物的生长等具有重要影响。为了研究草鱼在食物消化过程中, 肠道的酸碱度变化, 测定了草鱼肠道食物糜、肠液和黏膜的pH。结果显示, 随着食物的消化, 它们的pH都有下降的趋势。肠道食物糜pH在6.86±0.24到8.43±0.10之间, 肠液pH在7.14±0.22到8.63±0.02之间, 相同时间点相同肠段两者之间的pH差异很小, 并且在实验期间两者的pH变化趋势相同。黏膜pH在6.23±0.04到6.7±0.13之间, 为弱酸性。除了时间点12h外, 相同时间点和相同肠道部位黏膜的pH与食物糜、肠液的pH相比均有显著性差异(P<0.05)。分析发现草鱼摄食食物的pH与上述三相的pH之间均有显著性差异(P<0.05), 研究结果为草鱼消化生理及营养学研究提供了基础资料。     

Bioaccessibility of total bound fumonisin from corn flakes

Fumonisin B₁ (FB₁) is often found as a natural contaminant of corn and corn-based food. Several publications have demonstrated the presence of fumonisin bound to proteins and to other compounds of the matrix. In spite of the low oral bioavailability of FB₁ in rats, pigs, chickens, cows, and monkeys, FB₁ can cause agriculturally significant disease and possibly human cancer. The aim of this work was to determine the bioaccessibility of total bound FB₁ (TB FB₁) (percentage of TB FB₁, released from corn flakes to the chyme) after in vitro digestion. Two samples of corn flakes washed with solvents were incubated with gastrointestinal tract solutions simulating saliva plus stomach and duodenal juices. After hydrolysis of the chyme with KOH, TB FB₁ was determined as hydrolyzed FB₁ (HFB₁). The bioaccessibility of TB FB₁ in chyme from corn flakes was 37–64%, indicating that these derivatives should be considered in evaluation of exposure to fumonisin.     

Milk protein digestion and lysosomal proteinases of the ileal mucosa in young rats]

The proteolytic activity of lysosomal and pancreatic proteinases was studied in the chyme and tissue homogenates of the jejunum and ileum of 12- and 30-day rats in order to elucidate whether lysosomal proteinases of the mucous membrane of the ileum participate in cavitary digestion. During milk feeding the proteolytic activity of acid (lysosomal) proteinases in the ileum was 3 times greater than in the jejunum, which has been demonstrated both for the mucous membrane and the contents of these parts of the small intestine. In rats on definitive nutrition the activity of acid proteinases from the jejunum and ileum remained almost unchanged both in the mucous membrane and in the contents. The data obtained also indicate that pancreatic proteinase absorbed from the chyme of the small intestine may participate in parietal digestion.     

Effect of pH on the proteinase activities in the intestine mucosa,chyme, and enteral microbiota in the piscivorous fish differing in their ecological traits

The effect of pH on the activity of proteinases of intestine mucosa, chyme, and enteral microbiota was studied in three piscivorous fish species of the Rybinsk Reservoir differing in their ecological traits: pike Esox lucius, burbot Lota lota, and zander Sander lucioperca. In all fish species, studied pH of ten is optimal for the functioning of proteinases of intestine mucosa; in chyme proteinases, optimal pH values vary from six to ten. Optimal pH for functioning of proteinases of enteral microbiota is seven for zander and pike; pH of nine, for burbot. High activity of chyme and microbiota proteinases within the diapason of pH values of six to nine is a characteristic of burbot. Relative activity of proteinases of intestine mucosa in all fish species is not more than 15% of the maximal activity; that of chyme and enteral microbiota is lower than 40% in zander, close to 50% in burbot, and 80 and 50%, respectively, in pike. It is suggested that diversity of the patterns of pH-dependence of enteral microbiota proteinases relates to the specificity of microbiota in various ecological zones of the reservoir (littoral, sublittoral, and bathyal).     

磁场对血浆和胃粘膜内胃肠激素及胃动力效应的实验研究

目的:探讨腹部恒磁场作用,对大鼠急性胃损伤模型的治疗效应及其作用机制。方法:10只健康SD大鼠,以indomethacin胃灌注法复制急性胃损伤模型,以表面磁强度为1300-1600GS,钡铁氧体恒磁场作用大鼠腹部3小时,观察胃损伤指数及病理损伤积分,同时对血浆中内皮素(endothelin,ET)、一氧化氮(nitricoxide,NO)、谷胱甘肽过氧化物酶(GSH-Px)及超氧化物岐化酶(SOD)水平进行比较。结果:恒磁场腹部作用后,大鼠胃损伤指数及病理损伤积分较对照组均显著减轻(p均<0.05);血浆ET-1和NO水平却无无明显改变(p均>0.05),血GSH-Px和SOD含量较对照组均明显升高(p均<0.05)。结论:腹部1300-1600GS恒磁场作用3小时,对大鼠急性胃损伤具有明显的治疗效应,磁场的这一效应可能与其增加血浆中清除氧自由基的GSH-Px和SOD活性有关。     

Water ingestion by rats fed a high-salt diet may be mediated, in part, by visceral osmoreceptors

After surgical removal of all salivary secretions ("desalivation"), rats increase their consumption of water while eating dry laboratory chow. In the present experiments, desalivated rats drank even more water while they ate "powdered" high-salt food (i.e., <15-mg food particles). The Na+ concentration of systemic plasma in these animals was not elevated during or immediately after the meal, which suggests that cerebral osmoreceptors were not involved in mediating the increased water intake. A presystemic osmoregulatory signal likely stimulated thirst because the Na+ and water contents of the gastric chyme computed to a solution approximately 150 mM NaCl. In contrast, desalivated rats drank much smaller volumes of water while eating "pulverized" high-salt food (i.e., 60-140-mg food particles), and the fluid mixture in the gastric chyme computed to approximately 280 mM NaCl solution. These and other findings suggest that the NaCl ingested in the powdered high-salt diet was dissolved in the gastric fluid and that duodenal osmoreceptors (or Na+-receptors) detected when the concentration of fluid leaving the stomach was elevated after each feeding bout, and promptly stimulated thirst, whereupon rats drank water until the gastric fluid was diluted back to isotonicity. However, when rats ate the pulverized high-salt diet, much of the NaCl ingested may have been embedded in the gastric chyme and therefore was not accessible to visceral osmoreceptors once it emptied from the stomach. Consistent with that hypothesis, fluid intakes were increased considerably when desalivated rats drank 0.10 M NaCl instead of water while eating either powdered or pulverized high-salt food.     

Rat colonic mucosal cell sialic acid metabolism in azoxymethane-induced tumours

Colonic tissue was examined from normal (control) rats and azoxymethane- (carcinogen-) treated animals. Tumour-bearing colons from azoxymethane-treated rats were divided into malignant and non-malignant areas. Mucosal cells were prepared from the three types of colonic tissue and then examined for DNA and protein content and for the activities of ten enzymes involved in sialic acid metabolism. Enzyme activities were related to either the protein or the DNA content of fractions. The DNA content of cell homogenates was significantly different between tumour and non-malignant tissue and between both these tissues and normal mucosa. The protein content of the 100000 X g membrane pellet and supernatant fraction did not vary significantly between normal and non-malignant material but both these tissues differed significantly from tumour tissue. Significant variation between normal control and tumour tissue was detected at all levels of sialic acid metabolism, including N-acetylhexosamine interconversion and phosphorylation, sialic acid formation and activation, CMP-NeuAc breakdown and transfer and sialic acid release from glycoconjugates. The results indicate that major changes at all levels of sialic acid metabolism are associated with malignancy in rat colonic mucosa. Some of these changes are apparent in non-malignant mucosa and may reflect a pre-malignant state.     

The influence of testosterone on activity of glycosidases and proteinases in the intestine of the sterlet (Acipenser ruthenus)

Observation of the influence of testosterone (0.7 mg/kg) on the activity of glycosidases and proteinases, which function in the chyme and the mucosa of the sterlet intestine (Acipenser ruthenus), revealed a decrease in enzyme activity of both chains as against that one typical for intact individuals. The activity of the investigated enzymes changes in both the experimental and control groups of fish. Nevertheless, they have unlike dynamics of this activity. In a number of cases, we indicated a significant increase in enzyme activity of both chains in comparison to the control group. We also observed an increase in activity of chyme glycosidases, which was significant on the 21st day as compared to intact fish.     

磁场对急性胃损伤的治疗效应及其机制的实验研究

目的:探讨腹部磁场作用,对大鼠血液及胃粘膜组织中胃泌素(gastrin,GAS)、胃动素(motilin,MTL)和生长抑素(somatostain,SS),以及胃排空的效应。方法:10只Wistar健康雄性大鼠,腹部接受表面磁强度为1300-1600GS,钡铁氧体恒磁场作用3小时,以放射免疫法,分别测定大鼠血及胃粘膜组织中GAS、MLT及SS含量,用99mTc标记的碳粉糊剂灌胃法,测试胃排空率。结果:恒磁场腹部作用后,大鼠血GAS、MLT及SS水平较对照组,均无显著变化(p均>0.05);胃粘膜组织中,GAS含量无明显改变(p>0.05),MLT水平明显升高(p<0.01),SS水平明显降低(p<0.01);胃排空率无明显改变(p>0.05)。结论:腹部1300-1600GS恒磁场作用3小时,均不能显著调节大鼠血中MLT和SS,以及血和胃粘膜组织内GAS水平;可明显影响胃粘膜内MLT及SS水平;对大鼠胃排空率无明显效应。     

Establishing the A. E. Watkins landrace cultivar collection as a resource for systematic gene discovery in bread wheat

Key message

A high level of genetic diversity was found in the A. E. Watkins bread wheat landrace collection. Genotypic information was used to determine the population structure and to develop germplasm resources.

Abstract

In the 1930s A. E. Watkins acquired landrace cultivars of bread wheat (Triticum aestivum L.) from official channels of the board of Trade in London, many of which originated from local markets in 32 countries. The geographic distribution of the 826 landrace cultivars of the current collection, here called the Watkins collection, covers many Asian and European countries and some from Africa. The cultivars were genotyped with 41 microsatellite markers in order to investigate the genetic diversity and population structure of the collection. A high level of genetic diversity was found, higher than in a collection of modern European winter bread wheat varieties from 1945 to 2000. Furthermore, although weak, the population structure of the Watkins collection reveals nine ancestral geographical groupings. An exchange of genetic material between ancestral groups before commercial wheat-breeding started would be a possible explanation for this. The increased knowledge regarding the diversity of the Watkins collection was used to develop resources for wheat research and breeding, one of them a core set, which captures the majority of the genetic diversity detected. The understanding of genetic diversity and population structure together with the availability of breeding resources should help to accelerate the detection of new alleles in the Watkins collection.     

The interaction between walker tumour cells and mucosa cells in the lamina propria of gastric mucosa in rats

One series of 12 rats was exposed to X-irradiation (1500 R) of the stomach 19 days before implantation of Walker tumour cells in the gastric mucosa, and the frequency of tumour take and the extent of tumour growth after 10 days were compared with a second series with the same tumour implantation, but without X-ray exposure. In a third series simple gastric ulcers without tumour were produced by clamping the gastric wall with a heated (80 degrees) surgical needle holder, and the animals were killed 5-7 day later. All the rats were given injections of vinblastine sulfate 3 hours and of 3H-TDR 1 hour before sacrifice. In viewfields with diameter 180 mu the vinblastine-arrested mitoses and labelled cells on the tumour side of the tumour/mucosa border were calculated as percentages of all tumour cells. In the mucosa the total number of proliferating cells was counted at various distances from the border of the tumour or ulcer. No clear differences in the frequency of tumour take and the extent of tumour growth were found between the X-irradiated and the normal rat stomachs, and it is concluded that the X-ray exposure 3 weeks prior to tumour implantation did not reduce the normal mucosal resistance to tumour growth. The percentage of arrested mitoses and labelled cells in the tumour decreased one view field away from the mucosal border, and the number of proliferating cells in the mucosa bordering on the tumours showed a gradual fall with increasing distance up to 0.8-1.0 mm from the tumour border; within these distances, however, the numbers were much higher than at corresponding distances from edges of the ulcers. The Walker tumour thus seems to stimulate cell proliferation in mucosa to a much greater extent than a simple ulcer does. The causes of this phenomenon and the possible roles of "chalones" or "anti-chalones" are discussed.     

Reactions in the oral mucous membrane after exposure to CarisolvTM ‐ combined results from a clinical screening test in humans and an experimental study in rats

Objective: To evaluate reactions in the oral mucosa after direct contact with Carisolv^TM Setting: The Faculty of Odontology in Göteborg, Sweden. Subjects: 34 healthy persons for a clinical screening test and 35 Sprague Dawley rats for a histological study. Desing: Mixed Carisolv^TM or 0.5 % NaOCl were soaked in paper and applied to either side of the medial frenula of the lower lip of 34 persons. The solutions were left on the oral mucosa for three minutes. Inspection was made and photographs were taken immediately after exposure and also after 1 hour, 24 hours, and 72 hours. Mixed Carisolv^TM was applied in a similar manner as described above to 35 adult Sprague Dawley rats. The animals were killed and biopsies were taken immediately after Carisolv^TM exposure and also after 1 hour, 24 hours, and 48 hours. The biopsies were sectioned and prepared for histomorphometrical evaluation in light microscopy where cells were counted on regions from the epithelium layer deeper into the mucous membrane. Results: Some adverse reactions were detected on the oral mucosa of humans up to 24 hours after Carisolv^TM exposure for 3 minutes. The detected inflammatory reactions were slight and no patient felt any discomfort. The results of the histological study on rat did not show any statistically significant increase of the number of cells at any time after Carisolv^TM exposure. Conclusions: If the oral mucosa gets in direct contact with Carisolv^TM for 3 minutes no or only a weak inflammatory response may be expected.     

Nitric Oxide Synthase Inhibition Promotes Carcinogen-Induced Preneoplastic Changes in the Colon of Rats

l-Arginine is metabolized either to polyamines through arginase and ornithine decarboxylase (ODC) activities or to citrulline and nitric oxide (NO, nitrogen monoxide) through the NO synthase (NOS) pathway. Polyamine levels and ODC activity are high in tumor cells. The aim of this study was to test whether N(G)-nitro-l-arginine methyl ester (l-NAME), an inhibitor of NOS, modulates colon carcinogenesis. Adult male Wistar rats were treated with azoxymethane (AOM, 15 mg/kg ip), a chemical carcinogen, once a week for 2 weeks. One week after the second injection the rats were randomly divided into two groups. One group (n = 8) received l-NAME (10 mg/kg body wt/day) in drinking water. The control group (n = 8) received tap water. After 5 weeks, the rats receiving l-NAME showed enhanced mean basal arterial blood pressure, decreased heart rate, and a significant decrease of the cGMP content in the colonic mucosa. In both groups, AOM induced the formation of colonic aberrant crypt foci (ACF). In l-NAME-treated rats, the number of ACF was higher than in controls by 47%. ODC activity was enhanced by 11-fold. S-Adenosyl-methionine-decarboxylase activity and putrescine concentration were significantly increased in the colonic mucosa of l-NAME-treated rats. The data suggest that l-NAME promotes carcinogen-induced preneoplastic changes in the colon by inhibiting NOS activity and by stimulating polyamine biosynthesis.     

Rapid onset of (R)-α-methylhistamine protection in response to ethanol-induced histologic damage in rat gastric mucosa

The influence of pretreatment with (R)-α-methylhistamine, selective agonist of histamine H₃ receptors, has been investigated on gastric mucosal lesions at different time intervals, from 5 to 60 minutes, after administration of absolute ethanol in the rat. The amount and depth of lesions were quantitatively evaluated by light microscopy. In rats pretreated with (R)-α-methylhistamine, the integrity of the mucosa was preserved in approximately 80% of the total mucosal length measured despite ethanol challenge. Prevention of lesion formation was as great at 5 min after ethanol administration as at 60 min. When present, damage involved mainly superficial mucosa and lesions extending deeply into the gland region were evident in 1–2.5% of the total mucosa. Present findings indicate that mechanisms by which (R)-α-methylhistamine operates enable the mucosa to counteract damage just from the moment of exposure to ethanol and that protection is exerted both on surface and pit cells and on gastric glands.     

Effect of dexamethasone on activity of glycosidases and proreinases of intestine of sterlet <Emphasis Type="Italic">Acipenser ruthenus</Emphasis>

Effect of dexamethasone (2.0 mg/kg) on activity of enzymes hydrolyzing proteinaceous and carbohydrate food components in the intestine of the starlet Acipenser ruthenus is studied. Dexamethasone modifies the activity of proteinases more than of glycosidases. As a rule, the hormone significantly decreases the level of proteolytic and general amylolytic activity of the intestinal mucosa and chyme in comparison with intact fish on the first day into the experiment and increases it on the 7th or 14th day. The dynamics of activity was different in enzymes of different chains (glycosidase and proteinase) and preparations (the mucosa and chyme).     

EFFECTS OF CHRONIC STEROID INGESTION ON GASTRODUODENAL EPITHELIAL RENEWAL IN THE RAT

Steroids may predispose to peptic ulcer formation. One possible mechanism could be via alteration of normal epithelial renewal. to study the effects of steroids on gastroduodenal epithelial renewal, rats received hydrocortisone sodium succinate in the drinking water to deliver a dose of 10 mg/kg per day. Control rats received plain water. After 4 weeks, the rats were injected intraperitoneally with tritiated thymidine, to label proliferating cells, and killed 1 hr later, to determine measurements of epithelial proliferation, or 24 hr later to determine measurements of epithelial migration. Sections of fundus, antrum and post-pyloric duodenum were processed for light microscopy and autoradiography. In fundic and antral mucosa, steroid treatment resulted in a reduction in the number of labelled cells and in the size of the proliferative zone and, in the fundus, the mucosal thickness was reduced. In the duodenum, although the number of labelled cells remained unchanged, steroid treatment did decrease the number of cells in the proliferative zone; further, crypt depth was reduced in steroid-treated rats, but villous height was increased, resulting in an overall increase in mucosal thickness. Epithelial migration was also depressed in fundic and antral mucosa, but appeared to be accelerated in the duodenum of steroid-treated rats. These studies indicate that although, in the duodenum, the effects of steroids on epithelial renewal are complex, in the stomach chronic steroid ingestion depresses epithelial renewal both in fundic and antral mucosa. This inhibition of epithelial renewal in the stomach may contribute to the ulcerogenic action of steroids by either rendering the mucosa susceptible to the effects of other ulcerogens or by retarding the healing of existing mucosal lesions.