Oxidative phosphorylation and its coupling to mitochondrial creatine and adenylate kinases in human gastric mucosa

Energy metabolism in gastrobiopsy specimens of the antral and corpus mucosa, treated with saponin to permeabilize the cells, was studied in patients with gastric diseases. The results show twice lower oxidative capacity in the antral mucosa than in the corpus mucosa and the relative deficiency of antral mitochondria in complex I. The mucosal cells expressed mitochondrial and cytosolic isoforms of creatine kinase and adenylate kinase (AK). Creatine (20 mM) and AMP (2 mM) markedly stimulated mitochondrial respiration in the presence of submaximal ADP or ATP concentrations, and creatine reduced apparent Km for ADP in stimulation of respiration, which indicates the functional coupling of mitochondrial kinases to oxidative phosphorylation. Addition of exogenous cytochrome c increased ADP-dependent respiration, and the large-scale cytochrome c effect (>or=20%) was associated with suppressed stimulation of respiration by creatine and AMP in the mucosal preparations. These results point to the impaired mitochondrial outer membrane, probably attributed to the pathogenic effects of Helicobacter pylori. Compared with the corpus mucosa, the antral mucosa exhibited greater sensitivity to such type of injury as the prevalence of the large-scale cytochrome c effect was twice higher among the latter specimens. Active chronic gastritis was associated with decreased respiratory capacity of the corpus mucosa but with its increase in the antral mucosa. In conclusion, human gastric mucosal cells express the mitochondrial and cytosolic isoforms of CK and AK participating in intracellular energy transfer systems. Gastric mucosa disease is associated with the altered functions of these systems and oxidative phosphorylation.     

Inflammatory changes in the gastric mucosa of patients with idiopathic non-ulcer dyspepsia and the effect of colloid bismuth treatment on the course of inflammation]

The studies were aimed at the assessment of the coexistence of non-ulcer dyspepsia with chronic gastritis and Campylobacter pylori infection, and of the effect of therapy with De-Nol on the course of such disease. The studies involved 50 patients with non-ulcer dyspepsia. Prior to and after the treatment with De-Nol samples of the mucosa collected from the antrum and corpus of the stomach have been examined histologically with urease test indicating C. pylori infection. Chronic gastritis of the antral mucosa membrane and/or mucosa of the corpus of the stomach has been found in 36 patients, and normal mucosa in 14 patients. Therapy with De-Nol produced statistically significant improvement. Totally histological improvement has been noted in 77.1% of patients with inflammation of the antral mucous membrane and in 64.3% of patients with inflammation of the corporeal gastric mucosa. Campylobacter pylori has been eradicated in all patients with chronic gastritis. De Nol eliminates or significantly lowers an inflammation in the antrum and/or corpus of the stomach. Its action is related to the eradication of Campylobacter pylori infection.     

Effects of restraint stress on catecholamine concentrations in the glandular stomach of rats

Restraint stress is known to induce gastric ulcers in rats. Peripheral sympathetic activity and catecholamines are involved in the pathogenesis of these gastric ulcers. The aim of the present study was to evaluate the effects of restraint on mucosal and muscle catecholamine concentrations in the glandular stomach of rats. In unrestrained rats, noradrenaline concentration was higher in the muscle than in the mucosa of the glandular stomach (629 +/- 106 vs 18 +/- 3 pg/mg and 217 +/- 37 vs 18 +/- 8 pg/mg, respectively in the corpus and the antrum, p less than 0.01). This can be explained by the existence of an abundant noradrenergic innervation in the muscle layer. After 20 hours of restraint, adrenaline and noradrenaline concentrations were significantly decreased in adrenals, in comparison with unrestrained animals (255 +/- 53 vs 638 +/- 160 ng/mg and 113 +/- 17 vs 198 +/- 37 ng/mg, respectively for adrenaline and noradrenaline, p less than 0.05). In the glandular stomach, noradrenaline and adrenaline concentrations in restrained rats were not significantly different from those in unrestrained rats. However, adrenaline concentrations in the muscle of restrained rats were higher than in the mucosa. Moreover, restraint induced a significant decrease in dopamine concentration in the antral mucosa (from 100 +/- 12 pg/mg in unrestrained rats to 15 +/- 5 pg/mg in restrained rats), suggesting that a depletion in dopamine in the antral mucosa could be one of the pathogenetic factors involved in antral gastric stress-induced ulcers in rats.     

Regeneration of endocrine cells in the stomach

A mucosal defect was produced by cryosurgery in the antral and the fundic wall of the rat stomach, and regeneration of gastric endocrine cells was studied 50, 100 and 200 days after operation. Fifty days after the operation, the mucosal defect was completely covered with regenerated epithelium. The regenerated mucosa both in the antral and in the fundic region consisted of mucinous glandular structures. The regenerated mucosa in the corpus remained pseudopyloric in type even 200 days after operation. Regardless of the time after operation, regeneration of endocrine cells was always observed. We could identify G cells and EC cells in the regenerated mucosa of the antrum, and EC cells, A cells and AL cells in the regenerated mucosa of the corpus, respectively. By electron microscopy, endocrine-exocrine cells were frequently encountered. These cells had two different types of intra-cytoplasmic granules; one was an endocrine-specific, small electron-dense granule, and the other a large, lucent mucin droplet-like granule. These findings indicate that the endocrine cells of the stomach are formed from endodermal precursor cells.     

Effective use of rabbit gastric antral mucosal slices in prostaglandin synthesis and metabolism studies

Intact slice preparations of rabbit stomach (antral mucosa, corporal mucosa, antral muscle and corporal muscle) were incubated and the released prostaglandins (PGs) were measured by reverse-phase high-performance liquid chromatography using 9-anthryldiazomethane for derivatization. With respect to total PG production, the highest amounts were generated by antral mucosal slices. Antral mucosal slices produced PGE2, 6-keto PGF1 alpha, thromboxane B2, PGF2 alpha and PGD2 (in descending order of magnitude) and possessed a high capacity for producing 13,14-dihydro-15-keto derivatives of both PGE2 and PGF2 alpha. Studies utilizing aspirin, EGTA or Ca2+ revealed that PG release by antral mucosal slices in the present in vitro system reflects a composite of the activities of phospholipase A3, PG cyclooxygenase and PG-metabolizing enzymes. These results show that antral mucosal slices will be useful in physiological and pharmacological studies on PG synthesis and metabolism of the stomach.     

Mechanisms in regulating the release of serotonin from the perfused rat stomach

The mechanisms regulating the release of serotonin into the portal circulation as well as into the gastric lumen were studied in the isolated vascularly and luminally perfused rat stomach. Immunohistochemical study of the rat stomach showed that serotonin-containing enterochromaffin (EC) cells were densely packed in the antral mucosa, sparsely scattered in the corpus, and not found in the fundus. Such morphological findings suggest that serotonin detected in this study may have originated from antral EC cells. Luminal acidification stimulated the vascular release of serotonin but did not affect the luminal release of serotonin. The basal release of serotonin into the vasculature was 10 times higher than that into the gastric lumen at intragastric pH 2. The vascular release of serotonin is regulated by stimulation from cholinergic nicotinic mechanisms, whereas inhibitory neurotransmitters such as vasoactive intestinal peptide and NO are probably not involved. Somatostatin and peptide YY originating from endocrine cells may exert direct inhibitory effects, possibly via somatostatin and peptide YY receptors on the EC cells, and a cholinergic muscarinic mechanism may exert indirect effects on the vascular release of serotonin via the muscarinic receptor on the endocrine cells.     

Activity of 3-oxo acid CoA-transferase, D-3-hydroxybutyrate dehydrogenase, hexokinase and carnitine palmitoyltransferase in the stomach and small and large intestine of the rat.

1. Activities of 3-oxo acid CoA-transferase, D-3-hydroxybutyrate dehydrogenase, hexokinase and carnitine palmitoyltransferase have been measured in the gastrointestinal tract. 2. Activity of 3-oxo acid CoA-transferase in the glandular mucosa of the stomach was as high as that in heart and kidney, and was 2--4 times greater than that in other regions of the gastrointestinal tract. It is suggested that metabolism of acetoacetate might support acid secretion on re-feeding after a period without food. 3. All regions of the gastrointestinal tract have the capacity to use ketone bodies, and it is likely that both muscle and mucosa will contribute to their utilization. 4. Activity of hexokinase was twice the rate of glucose utilization by the jejunum under anaerobic conditions. The maximal rate of glucose metabolism in the jejunum may not be substantially different from that in other regions of the gastrointestinal tract. 5. Starvation decreased the capacity for metabolism of glucose in several regions of the intestine. 6. Activities of carnitine palmitolytransferase in the stomach, jejunum and colon were similar, and about one-third of that in the liver. Activity in the jejunum was much higher than the apparent rate of oxidation of exogenous fatty acid. 7. The results do not suggest any large variation between tissues of the gastrointestinal tract in metabolism of glucose or fatty acids, whereas metabolism of ketone bodies may be more prominent in the stomach.     

The morphometric and immunohistochemical characteristics of the gastric and duodenal mucosa in systemic lupus erythematosus]

Histological, morphometric, and immunohistochemical studies of biopsy specimens from the mucosa of the body and antral portion of the stomach, the bulb and descending portion of the duodenum were performed in 27 children with systemic lupus erythematosis (SLE) and in 12 with chronic gastroduodenitis. The inflammatory infiltrate from SLE patients was found to contain higher levels of young and mature fibroblasts than that from patients with chronic gastroduodenitis, mature fibroblasts being prevalent. The inflammatory changes in the gastric and duodenal mucosa were ascertained to be associated with the progression of SLE. In exacerbation of SLE, the walls of vessels (arterioles) exhibited immune complexes classified mainly as IgG and, to a lesser degree, as IgM. In remission, the luminescence of the vessels decreased. The serum level of immunoglobins did not correlate with their regional production in the gastric and duodenal mucosa.     

Apoptosis in Helicobacter pylori gastritis is related to cagA status

BACKGROUND: Helicobacter pylori infection increases gastric epithelial cell apoptosis; however, the influence of cagA status is still controversial. We aimed to investigate if cagA status is related to apoptosis in H. pylori gastritis at different anatomic sites of the gastric mucosa. MATERIALS AND METHODS: We studied by immunohistochemistry (streptavidin-biotin method) pro-apoptotic (Bax and Bak) and antiapoptotic (Bcl-2 and Bcl-x) proteins expression, scored from 0 to 4, in gastric biopsies, at the antrum (lesser and greater curvatures), incisura, and corpus (greater curvature) from 50 patients with H. pylori gastritis (22 males, 28 females, median age 40 years) and eight non-infected patients (6 males, median age 39.6 years). H. pylori and cagA status were determined by polymerase chain reaction. RESULTS: Apoptotic proteins were expressed in a granular pattern, in the cytoplasm of foveolar cells; Bax and Bak expression was higher than Bcl-2 and Bcl-x in most cases and was significantly higher in patients infected by cagA-positive strains than in those infected by cagA-negative strains (p = .001). Bak expression was higher at the lesser curvature (antrum and incisura) than in the other regions (p = .002) and was correlated with atrophy. Anti-apoptotic proteins were significantly more expressed at the antral lesser curvature than in the other regions of the stomach (Bcl-2: p = .02; Bcl-x: p < .001). CONCLUSIONS: Infection with cagA-positive strains is significantly associated with overexpression of pro-apoptotic proteins in the gastric mucosa, mainly at the antral lesser curvature, which may have a role on atrophy development. Anti-apoptotic proteins were also overexpressed at the lesser curvature, which may occur to keep epithelial cell turnover or might be related to malignant transformation.     

Effects of rabbit gastrointestinal mucins and dextran on hydrochloride diffusion in vitro

We compared a viscous fingering formation of hydrochloric acid (HCl) in rabbit corpus, antral and duodenal mucins and with dextran under neutral and acidic conditions with respect to relative viscosity, molecular mass, and carbohydrate composition. The effect of desialyzation of duodenal mucin on the viscous fingering formation of HCl was also examined. HCl (0.1 N) was injected into 1% solutions of mucins and dextran and a subsequent viscous fingering formation was assessed based on an influx volume rate of HCl. A low influx volume rate indicates a high ability of the solutions to produce viscous fingers. The influx volume rate of HCl was lowest in duodenal mucin followed bl corpus mucin, antral mucin, and dextran at pH 7. The influx volume rate of HCl was inversely correlated with the relative viscosity of the solution. Maximum molecular masses were large in the order of corpus, antral, and duodenal mucins, and they were larger than dextran T2000. Rabbit gastrointestinal mucins were very polydisperse system. Duodenal mucin contains more sialic acid than gastric mucins; the influx volume rate of HCl increased in desialylated duodenal mucin. It is suggested that the higher ability of gastric mucins to prevent HCl diffusion than dextran were due to the differences in the molecular mass. The ability of duodenal mucin to prevent HCl diffusion was probably attributed to its high sialic acid content, which may reflect a physiological role of duodenal mucin in the duodenum that has to deal with HCl influx from the stomach.     

Characterization of metaplastic and heterotopic epithelia in the human gastrointestinal tract by the expression pattern of acyl-CoA synthetase 5

Metaplastic and heterotopic epithelia are frequently found in the human intestine. The recently cloned human acyl-CoA synthetase 5 (ACS5) is a key enzyme in providing cytosolic acyl-CoA thioesters. The aim of the study was to identify and to locate the expression of ACS5 in the gastric body and the small intestine with metaplasia or heterotopia by different methods. In the normal gastrointestinal tract, ACS5 was predominantly found in the villus epithelium of the small intestine, but not in the gastric mucosa. Of note, strong expression of ACS5 was also detectable in intestinal metaplasia of the stomach. Inversely, ACS5 expression could neither be detected in heterotopic gastric mucosa of the corpus type nor in gastric, pseudopyloric, or antral metaplasia of the small intestine. In conclusion, our data implicate that ACS5 is a suitable differentiating marker molecule in the gastrointestinal tract.     

Nutrient sensing receptors in gastric endocrine cells

Sensing protein breakdown products in the luminal content is of particular importance for the regulation of digestive activities in the stomach which are mainly governed by gastric hormones. The molecular basis for tuning the release of hormones according to the protein content is still elusive. In this study we have analysed the murine stomach for candidate nutrient receptors. As a promising candidate we have concentrated on the broadly tuned amino acid receptor GPRC6A. Expression of GPRC6A could be demonstrated in different regions of the murine stomach; especially in the gastric antrum. Using immunohistochemical approaches, a large cell population of GPRC6A-positive cells was visualized in the basal half of the antral gastric mucosa. Molecular phenotyping of GPRC6A-immunoreactive cells revealed that most of them contained the peptide hormone gastrin. A small population turned out to be immunoreactive for somatostatin. In search for additional amino acid receptors in antral gastric mucosa, we obtained evidence for expression of the gustatory amino acid receptor subunit T1R3 and the calcium-sensing receptor CaSR. Many CaSR-cells were found in the gastric antrum and most of them also contained gastrin; very similar to GPRC6A-cells. In contrast, T1R3 was found only in a small population of gastrin-negative cells. The finding that GPRC6A-and CaSR-receptors are both expressed in many if not all gastrin cells strongly suggests that both receptor types are co-expressed in the same cells, where they could form heterodimers providing a unique response spectrum of these cells.     

社群等级对金乌贼行为表型及能量代谢的影响

采用实验生态学方法,在室内水槽条件下研究了金乌贼(Sepia esculenta Hoyle,1885)繁殖过程中社群等级的形成对其行为表型和能量代谢的影响,分析测定了不同优势等级雌雄个体腕部肌肉和性腺组织中己糖激酶(Hexokinase, HK)、丙酮酸激酶(Pyruvate kinase, PK)、乳酸脱氢酶(Lactate dehydrogenase, LDH)、苹果酸脱氢酶(Malate dehydrogenase, MDH)、柠檬酸合酶(Citrate synthetase, CS)活性以及乳酸(Lactic acid, LD)含量。结果显示:(1)金乌贼繁殖期不同优势等级雌雄个体之间行为表型具有显著差异,优势雄性个体游动悬浮、争斗时间显著高于劣势个体,而优势雌性个体静止伏底时间高于劣势个体,游动悬浮时间低于劣势雌性;(2)优势雄性个体在争斗过程中主要通过无氧代谢提供能量,而处于游动悬浮状态时通过有氧代谢提供能量。主要表现在优势雄性个体肌肉中无氧代谢酶(PK、HK、LDH)活性显著高于劣势个体(P<0.05),有氧代谢酶(MDH、CS)活性也显著高于劣势个体,雌性个体之...     

Release of prostacyclin (PGI2) by the layers of corpus of rat stomach

Release of PGI2 by slices of muscularis and mucosa layers of rat corpus stomach was investigated. An anti-aggregatory substance that was released by slices of muscularis was identified as PGI2 in various bioassay systems including anti-serum against PGI2 as well as by stimulation of its generation with AA or PGH2 and by inhibition of this generation with indomethacin or tranylcypromine, respectively. PGI2 was the major PGs released from slices of muscularis. The release of PGI2 from muscularis surpasses a similar release of PGI2 from mucosa by a factor of 10. On the other hand, degradation of exogenous PGI2 was 4 times faster by mucosa than by muscularis slices. Our conclusion is that in the stomach corpus wall of rats, muscularis is the main source of PGI2, which may play a role in regulation of mucosal blood flow.     

雌雄罗氏沼虾应对低氧胁迫的行为生理响应

为查明雌雄罗氏沼虾应对低氧胁迫的行为生理响应,设置6.46(对照)、4.48和3.27 mg·L^-13种溶解氧水平,研究了雌、雄个体在胁迫6 d后肝胰脏和肌肉能量代谢酶活性及游泳和弹跳速度。结果表明: 溶解氧从6.46 mg·L^-1降至4.48 mg·L^-1,雌雄个体肌肉有氧代谢酶活性及游泳速度均显著下降,且雄性下降幅度小于雌性,厌氧代谢酶活性并无显著变化;溶解氧继续降至3.27 mg·L^-1,雌雄个体肌肉有氧代谢酶和厌氧代谢酶活性均显著下降,肝胰脏厌氧代谢酶中的乳酸脱氢酶(LDH)活性及弹跳速度显著下降,且雌性肝胰脏LDH活性下降幅度小于雄性。雌雄罗氏沼虾游泳速度与游泳足肌肉有氧代谢酶活性呈显著正相关,弹跳速度则与腹部肌肉厌氧代谢酶活性呈显著正相关。表明罗氏沼虾可以通过降低能量代谢水平应对低氧胁迫,但这种生理调节会导致运动能力下降,雄性优先将能量分配于肌肉以满足运动,雌性则优先保障肝胰脏能量供应。     

The optimal allocation of time and respiratory metabolism over the dive cycle

Because anaerobic metabolism is much less efficient than aerobicmetabolism in supplying energy, it is widely believed that diversrely predominantly on aerobic metabolism for diving. In thispaper, a time budget model, which assumes that the diver canuse either completely aerobic or partially aerobic metabolismwith additional anaerobic metabolism for diving, is developedand is used to make predictions about patterns in optimal allocationof time and respiratory metabolism during the dive cycle. Theresults derived from the model are (1) a diver that can varythe ratio of energy supplied anaerobically to total energy spentduring dive time is favored by natural selection, but the patternsof time allocation over the dive cycle by the diver do not differ fromthose of a diver that cannot vary the ratio. (2) Even if itis assumed that divers switch their metabolism for diving, anobvious upturn in the surface time with respect to dive timedoes not occur at the aerobic dive limit (ADL) but occurs beyondthe ADL. (3) Use of additional anaerobic metabolism can be favoredfor dives shorter than the ADL. These findings provide a usefulguide to understanding the factors that limit diving behavior.     

Postnatal changes of some enzymatic activities of energy supplying metabolism in the cortex, inner and outer medulla of the rat kidney

1. In rat kidney cortex, outer and inner medulla the development of activities of seven enzymes was investigated during postnatal ontogeny (10, 20, 30, 60 and 90 days of age). The enzymes were selected in such a manner, as to characterize most of the main metabolic pathways of energy supplying metabolism: hexokinase (glucose phosphorylation, HK), glycerol-3-phosphate dehydrogenase (glycerolphosphate metabolism or shunt, GPDH), triose phosphate dehydrogenase (glycolytic carbohydrate breakdown, TPDH), lactate dehydrogenase (lactate metabolism, LDH), citrate synthase (tricarboxylic acid cycle, aerobic metabolism, CS), malate NAD dehydrogenase (tricarboxylic acid cycle, intra-extra mitochondrial hydrogen transport, MDH) and 3-hydroxyacyl-CoA-dehydrogenase (fatty acid catabolism, HOADH). 2. The renal cortex already differs metabolically from the medullar structures on the 10th day of life. It displays a high activity of aerobic breakdown of both fatty acids and carbohydrates. Its metabolic capacity further increases up to the 30th day of life. 3. The outer medullar structure is not grossly different from the inner medulla on the 10th day of life. Further it differentiates into a highly aerobic tissue mainly able to utilize carbohydrates. It can, however, to some extent, also utilize fatty acids aerobically and produce lactate from carbohydrates anaerobically. 4. The inner medullar structure is best equipped to utilize carbohydrates by anaerobic glycolysis, forming lactate. This feature is already pronounced on the 10th day of life, its capacity increases to some extent during postnatal development, being highest between the 10th and the 60th day of life.     

Marked increase in gastric histidine decarboxylase activity in patients with hypergastrinemia.

Histidine decarboxylase (HDC) activity and histamine content were measured in endoscopic gastric biopsy specimens of 19 control subjects with normogastrinemia and 6 patients with hypergastrinemia. In controls, the HDC activity was 3 fold higher in fundic mucosa (120 +/- 13 fmol/min/mg protein, mean +/- S.E.) than in antral mucosa (39 +/- 5 fmol/min/mg protein). In patients with hypergastrinemia, an extremely high HDC activity (713 +/- 181 fmol/min/mg protein) was observed in fundic mucosa, although the HDC activity in antral mucosa was not significantly different from that of controls. The histamine content in fundic mucosa was also significantly higher in patients with hypergastrinemia than in controls but no significant difference was seen in histamine content in antral mucosa between the two groups. These results are compatible with the hypothesis that in man, as well as in rat, histamine synthesis in fundic mucosa is enhanced by gastrin.