幽门螺杆菌感染对延缓乙酸诱导大鼠胃溃疡愈合的实验研究

本工作旨在观察幽门螺秆菌（Ｈｅｌｉｃｏｂａｃｔｅｒｐｙｌｏｒｉ,ＨＰ）感染对大鼠乙酸性胃溃疡愈合的影响。实验发现,大鼠发生乙酸性溃疡后,一次性接种ＨＰ几乎使所有大鼠感染,并引起胃溃疡的自然愈合明显减慢;组织学和生化检测观察到ＨＰ组大鼠胃溃疡病灶处有更多炎症细胞浸润,以中性粒细胞为主,未受溃疡累及的胃窦和胃后壁粘膜也有炎症细胞浸润;免疫组化研究发现ＨＰ组胃粘膜出现较多的ＩＬ－８阳性细胞;此外发现ＨＰ组胃粘膜ＢｒｄＵ标记细胞显著减少,既粘膜上皮的再生减慢。结果提示,ＨＰ感染延缓乙酸性溃疡的愈合,后者与ＨＰ感染后增加ＩＬ－８表达所诱导更强的炎症反应和粘膜细胞再生减慢有关。     

Neuroendocrine (ECL cell) differentiation of spontaneous gastric carcinomas of cotton rats (Sigmodon hispidus).

BACKGROUND AND PURPOSE: Female inbred cotton rats develop adenocarcinomas in the oxyntic mucosa. Since a female preponderance is typical for enterochromaffin-like (ECL) cell tumors, we examined such tumors for ECL cells. Gastrin plays a decisive role in ECL cell tumorigenesis, so blood gastrin concentration and gastric mucosal pH were measured. METHODS: The stomachs from six female cotton rats (6 to 8 months old) were studied histologically, and at euthanasia, gastric mucosal pH was determined. Euthanasia was performed on 15 other female cotton rats of similar age for determination of blood gastrin values by radioimmunoassay (RIA) and gastric mucosal pH. Rats were classified macroscopically to have normal or thick oxyntic mucosa, with or without tumor. RESULTS: Among the six cotton rats studied histologically, two 6-month-old rats had normal and two others had thick gastric mucosa, whereas two 8-month-old rats had thick mucosa with tumors. The ECL cells were markedly hyperplastic in all rats with thick mucosa, and ECL cells were found in the neoplastic parenchyma. All cotton rats with normal-appearing gastric mucosa had pH <2.5, whereas 14 rats with thick mucosa had pH >3.1 and hypergastrinemia. CONCLUSIONS: Gastrin may play a major role in ECL cell hyperplasia and, perhaps, in adenocarcinoma genesis.     

Growth pattern of the polypeptide-YY cell population in the upper digestive tract of the rat during the perinatal period and after weaning

Summary The distribution of polypeptide-YY cells within the gastric and duodenal mucosa of the rat and the development of their populations were examined daily from 3 days before birth until day 8 postpartum and after weaning, on day 25 postpartum, using a precise technique of quantification. Polypeptide-YY cells appeared in the stomach around the 19th day of gestation. They were always more numerous in the antral mucosa and particularly in the pyloric sphincter area than in the fundic mucosa. Immunogold staining at the electron-microscopic level revealed that, in the antrum, polypeptide-YY was colocalised with gastrin in endocrine cells mainly of type G and, more rarely, in cells of intestinal type IG. Comparison of the gastrin and polypeptide-YY cell populations in the same rats indicated that, except at day 6 postpartum, there were fewer gastric polypeptide-YY cells than immunoreactive gastrin cells and that polypeptide-YY cells were 8 times less numerous than gastrin cells at day 25 postpartum. Polypeptide-YY cells were clearly present in the duodenum of the 19-day-old embryo. This population increases with age until day 8 postpartum, then significantly decreases (by 87%) between days 8 and 25 postpartum. Because polypeptide-YY may inhibit secretion of gastric acid, it is possible that the presence of significant population of polypeptide-YY cells in the upper digestive tract during the first postnatal week of life may play a role (endocrine or paracrine) in the decreased acid secretion occurring in the newborn rat.     

Impact of ethanol on innate protection of gastric mucosal epithelial surfaces and the risk of injury.

Earlier investigations on the effect of ethanol on synthesis and posttranlational glycosylation of gastric mucus glycoprotein (mucin) revealed quantitative changes in the apoprotein assembly, glycosylation, and mucin retention on the mucosal surface (Slomiany et al.., Alcoholism: Clin. Exp. Res. 21, 417-423, 1998). To assess whether metabolic consequences of ethanol ingestion, documented in the in vitro system are also occurring in vivo the rats were subjected to 8 weeks of ethanol containing liquid diet. The retention of mucin on the surface of gastric mucosa was quantitated by measuring the binding of gastric mucin to Mucin Binding Protein (MBP) of gastric mucosa. The results were compared with those obtained with the rats subjected to pair-feeding the isocaloric-control diet. Before alcohol administration, and in two weeks' intervals thereafter, the gastric contents from the animals was collected and mucin purified. After 8 weeks of the respective diet, the animals were sacrificed and their gastric mucosa used for MBP preparation. The binding of mucin to MBP before ethanol, and after 2, 4, 6, and 8 weeks of ethanol diet was quantitated with Enzyme Linked Lectin Assay (ELLA). The study with standard mucin revealed that binding of mucin to MBP differs substantially between individual animals. The same variability in binding was observed with the individual mucin preparations collected at the onset of the experiment. However, with the progression of ethanol feeding, the mucin samples besides displaying the variable and animal-specific binding to MBP at the initiation of the experiment, also showed a dramatic decrease in binding. In five animals, after two weeks of ethanol diet, mucin binding to MBP decreased by 50%; in two animals, the drastic decrease in binding was observed in mucin collected after four weeks of alcohol feeding; and in one animal a 20% decrease in binding persisted for six weeks, and then decreased to 50% in the last collection. Also, in two animals, the mucin collected after 8 weeks of ethanol feeding retained only 6-9% of the initial binding capacity. In contrast, in pair-fed controls, the mucin binding to MBP remained the same or increased up to 20%. Results of the studies, performed on mucin of the individual animals and matching preparations of MBP, showed that each animal expresses different degree of mucin binding. Moreover, in chronic ethanol ingestion, the individual variations are accompanied by a decrease in mucin binding to MBP. Since the observed decrease in binding occurred in samples containing the same preparation of MBP, the component affected by alcohol resides on mucin. Thus, considering the in vitro impact of ethanol on generation of carbohydrate chains in Golgi, and the finding on mucin oligosaccharides-dependent mucin-MBP complex formation, we conclude that ethanol impairs the synthesis of mucin oligosaccharide structures required for binding with MBP, and the retention on gastric mucosal surfaces.     

胃缺血-再灌注对大鼠胃黏膜细胞凋亡和增殖的影响

本研究采用大鼠胃缺血-再灌注（gastricischemia-reperfusion,GI-R）模型（夹闭腹腔动脉30 min后再灌注）,通过组织学、免疫组化等方法,研究GI-R不同时间（0、0.5、1、3、6、24、48、72 h）对胃黏膜细胞凋亡和增殖的影响.结果发现,单纯缺血30 min胃黏膜损伤较轻,再灌注后损伤逐渐加重,胃黏膜的凋亡细胞迅速增加,而增殖细胞迅速减少;至再灌注后1 h达高峰;之后胃黏膜开始修复,凋亡细胞逐渐减少,增殖细胞逐渐增加;至再灌注后24 h胃黏膜细胞增殖达高峰;再灌注后72 h胃黏膜基本恢复正常.上述结果提示,在GI-R中,胃黏膜损伤主要由再灌注引起,凋亡细胞增加;然后胃黏膜启动自我修复机制,增殖细胞逐渐取代损伤细胞,3 d左右就可基本修复,表明胃黏膜细胞具有很强的自我修复能力.     

Cell kinetic study on GM colonies using autoradiography and collagen gel culture with special reference to unique proliferation of eosinophils

Using a newly developed technique of autoradiography and collagen gel culture, a kinetic study on human GM colonies was attempted. Colonies of immature cells appeared first on day 5. The number of mixed colonies (mixture of immature cells, neutrophils, and/or monocyte-macrophages) and neutrophil colonies attained a maximum on days 8 to 10 and a broad peak of monocyte-macrophage colonies was observed on days 11 to 16. Eosinophil colonies appeared first on day 12, reached a maximum on day 18, and then gradually decreased. A detailed analysis of the order of appearance of the colonies suggests that mixed, neutrophil and monocyte-macrophage colonies originate from immature cell colonies or clusters, while eosinophil colonies do not. An autoradiographic study was designed to study the proliferation characteristics of each colony. Labeling indices (LI) with 3H-TdR of the cells in immature cell colonies were always high. LI of the cells in differentiated colonies such as neutrophil, monocyte-macrophage, and mixed colonies were low throughout the observation period. In contrast, LI of the cells in eosinophil colonies were constantly high regardless of the size of cell aggregates and the duration of the culture period. Both mitotic indices and mean grain counts on the nuclei of eosinophils were similar to those of immature cells. These results suggest that eosinophil colonies develop from their own small clusters and that eosinophils retain a fairly good proliferative capacity even when differentiated to the level in which specific granules appear in the cytoplasm.     

Mast cells in the rat gastric mucosa are not primarily responsible for PGD2 generation

The present study investigates the contribution of gastric mast cells on PGD2 generation in rat gastric mucosa. Cold-restraint induced stress or i.v. carbachol injection methods were used for gastric mast cell degranulation. In 19 stressed, 15 carbachol-infused and 14 control rats, gastric mast cell counts and gastric mucosa PGD2 assay were performed. Gastric mucosal content of PGF2 alpha was also determined in carbachol infused and control rats. The mean number of gastric mast cells was significantly lower in stressed and carbachol infused than in control rats. Despite these differences in gastric mast cell counts, neither PGD2 or PGF2 alpha contents in the gastric mucosa were significantly different in mast cells degranulated rats than in control animals. These results suggest another source of PGD2 in the rat gastric mucosa other than mast cells.     

Role of gastrin in the development of gastric mucosa,ECL cells and A-like cells in newborn and young rats

Histamine-producing ECL cells and ghrelin-producing A-like cells are endocrine/paracrine cell populations in the acid-producing part of the rat stomach. While the A-like cells operate independently of gastrin, the ECL cells respond to gastrin with mobilization of histamine and chromogranin A (CGA)-derived peptides, such as pancreastatin. Gastrin is often assumed to be the driving force behind the postnatal development of the gastric mucosa in general and the ECL cells in particular. We tested this assumption by examining the oxyntic mucosa (with ECL cells and A-like cells) in developing rats under the influence of YF476, a cholecystokinin-2 (CCK(2)) receptor antagonist. The drug was administered by weekly subcutaneous injections starting at birth. The body weight gain was not affected. Weaning occurred at days 15-22 in both YF476-treated and age-matched control rats. Circulating gastrin was low at birth and reached adult levels 2 weeks after birth. During and after weaning (but not before), YF476 greatly raised the serum gastrin concentration (because of abolished acid feedback inhibition of gastrin release). The weight of the stomach was unaffected by YF476 during the first 2-3 weeks after birth. From 4 to 5 weeks of age, the weight and thickness of the gastric mucosa were lower in YF476-treated rats than in controls. Pancreastatin-immunoreactive cells (i.e. all endocrine cells in the stomach) and ghrelin-immunoreactive cells (A-like cells) were few at birth and increased gradually in number until 6-8 weeks of age (control rats). At first, YF476 did not affect the development of the pancreastatin-immunoreactive cells, but a few weeks after weaning, the cells were fewer in the YF476 rats. The ECL-cell parameters (oxyntic mucosal histamine and pancreastatin concentrations, the histidine decarboxylase (HDC) activity, the HDC mRNA levels and serum pancreastatin concentration) increased slowly until weaning in both YF476-treated and control rats. From then on, there was a further increase in the ECL-cell parameters in control rats but not in YF476 rats. The postnatal development of the ghrelin cells (i.e. the A-like cells) and of the A-like cell parameters (the oxyntic mucosal ghrelin concentration and the serum ghrelin concentrations) was not affected by YF476 at any point.We conclude that gastrin affects neither the oxyntic mucosa nor the endocrine cells before weaning. After weaning, CCK(2) receptor blockade is associated with a somewhat impaired development of the oxyntic mucosa and the ECL cells. While gastrin stimulation is of crucial importance for the onset of acid secretion during weaning and for the activation of ECL-cell histamine formation and secretion, the mucosal and ECL-cell growth at this stage is only partly gastrin-dependent. In contrast, the development of the A-like cells is independent of gastrin at all stages.     

Interphasic nucleolar organizer regions expression and cell kinetics evaluation during gastric carcinogenesis induced by nitrosoguanidine in the rat.

An increased number of interphasic nucleolar organizer regions containing ribosomal cistrons associated with argyrophilic proteins (AgNORs) has been described in human malignant tumor cells. In this study variations in AgNOR numbers have been compared with changes of cell kinetics, evaluated by the mitotic count (MC) and bromodeoxyuridine labeling index (BrdU LI), during gastric carcinogenesis induced with N-methyl-N'-nitro-N-nitrosoguanidine (NG) in rats. Significant differences (2 P < 0.005) in AgNOR mean numbers, evaluated in the antral isthmic cells, in MC mean values and BrdU LI, evaluated in the whole antral cellular population, were found when comparing areas of acute gastritis, atrophy and hyperplasia in NG-treated rats with the normal mucosa in controls. No differences were observed in MC and BrdU LI between normal antrum and carcinoma cells which showed an AgNORs mean number lower than in the isthmic cells of controls (2 P < 0.005). Moreover, significant correlations were found comparing changes in AgNOR numbers with MC (r = 0.89, P < 0.001) and BrdU LI (r = 0.66, P < 0.001) in different lesions. These data show that evaluation of AgNOR numbers does not allow the identification of malignant cells in NG-induced gastric carcinoma. However AgNOR quantification seems to be a reliable index of cell kinetics and related well with the cellular dividing fraction.     

Effects of deflazacort and cortisone on cellular proliferation in the rat thymus

Deflazacort is a relatively new glucocorticoid with significant immunosuppressant activity and presumably fewer side effects. The present study was designed to compare the effects of deflazacort on the proliferative activity of thymus cells and thymolysis with the growth inhibition. We treated Long-Evans rats for nine days with cortisone (CORT, 5.0 mg/day), deflazacort (DFZ, 0.15 mg/day), and control vehicle (CTRL). Animals were sacrificed 1 hour after injection of bromodeoxyuridine (BrdUrd) on day 10. BrdUrd-labeled thymic cells were quantified without knowledge of treatment. A Labeling Index (LI), expressed as the number of BrdUrd BrdUrd-labeled cells per 100 total cells and the Numerical Density (ND), expressed as the total number of cells per 100 microm(2) were calculated. Treatment with either glucocorticoid resulted in a significant and equal decrease of thymus weight, indicating a marked reduction in total immunogenic tissue. A general alteration of thymic histological structure occurred in the CORT group. The LI was not different between CTRL and DFZ groups, 6.9 and 7.9% of cells were labeled respectively. In the CORT group, the LI was 2.5%. With respect to Numerical Density, the CTRL group had the greatest value (14.6 +/- 0.4 cells/100 microm(2)), with the DFZ (12.3 +/- 0.06 cells/100 microm(2)) and CORT groups being significantly lower (10.4 +/- 0.5 cells/100 microm(2)). Although regression analysis of thymus weight pointed to bioequivalence of the glucocorticoid dosages used, BrdUrd-labeling raised the possibility that the cells still present in the thymus of DFZ-treated animals retained, at least partially, their normal capacities for proliferation.     

Chloroacetonitrile (CAN) induces glutathione depletion and 8-hydroxylation of guanine bases in rat gastric mucosa

Chloroacetonitrile (CAN) is detected in drinking-water supplies as a by-product of the chlorination process. Gastroesophageal tissues are potential target sites of acute and chronic toxicity by haloacetonitriles (HAN). To examine the mechanism of CAN toxicity, we studied its effect on glutathione (GSH) homeostasis and its impact on oxidative DNA damage in gastric mucosal cells of rats. Following a single oral dose (38 or 76 mg/Kg) of CAN, animals were sacrificed at various times (0-24 h), and mucosa from pyloric stomach were collected. The effects of CAN treatment on gastric GSH contents and the integrity of genomic gastric DNA were assessed. Oxidative damage to gastric DNA was evaluated by measuring the levels of 8-Hydroxydeoxyguanosine (8-OHdG) in hydrolyzed DNA by HPLC-EC. The results indicate that CAN induced a significant, dose- and time-dependent, decrease in GSH levels in pyloric stomach mucosa at 2 and 4 hours after treatment (56 and 39% of control, respectively). DNA damage was observed electrophoretically at 6 and 12 hours following CAN administration. CAN (38 mg/Kg) induced significant elevation in levels of 8-OHdG in gastric DNA. Maximum levels of 8-OHdG in gastric DNA were observed at 6 hours after CAN treatment [9.59+/-0.60 (8-OHdG/10(5)dG) 146% of control]. When a high dose of CAN (76 mg/Kg) was used, a peak level of 8-OHdG [11.59+/-1.30 (8-OHdG/10(5)dG) 177% of control] was observed at earlier times (2 h) following treatment. When CAN was incubated with gastric mucosal cells, a concentration-dependent cyanide liberation and significant decrease in cellular ATP levels were detected. These data indicate that a mechanism for CAN-induced toxicity may be partially mediated by depletion of glutathione, release of cyanide, interruption of the energy metabolism, and induction of oxidative stress that leads to oxidative damage to gastric DNA.     

A quantitative study of epithelial alterations during the early stages of experimental colonic tumorigenesis in mice

The weekly administration of 1,2-dimethyl-hydrazine (DMH) by subcutaneous injection for a period of 16-20 weeks is a well known procedure for producing colonic tumors in mice and rats. Quantitative histomorphological, histochemical and kinetic studies, as well as investigation of the significance of epithelial cell density were carried out in mice between the 7th and the 91st day after the first DMH injection. These studies showed that between the 28th and the 35th day, several simultaneous alterations in the colonic epithelium involving modification of glandular form, decreased mucus secretion, an increase in epithelial cell density and an increase in the number of S phase cells (BrdU labeling index: LI). Around the 35th day, the glands tended to expand and from the 35th to the 63rd day, they were stretched and displayed compartments of dedifferentiated and non-mucinous crypts (DNMC). In these crypts the cell density became very high, reaching twice the control value on the 91st day. This feature was accompanied by alteration in cell morphology and by an increase in the available basement membrane area. A decrease in mucus secretion was apparent from the 14th day and by the 63rd day, mucus secretion was only about 60% of the control value in all crypts. The LI was increased until the 35th day following which a paradoxical and progressive decrease occurred in all glandular compartments.     

Dynamics of DNA synthesis in the gastric mucosa in ulcer

Anomalous DNA synthesis was seen in the stomach mucosa of mice with experimental stomach ulcer during different phases of the ulcerous process, using histoautoradiography. At the early stage of ulcer formation a decrease in the label index (LI) is seen. Formation of the ulcer, morphologically similar to the shronic one, is accompanied by growth of the number of DNA-synthesizing cells in its margins. Over a period of ulcer healing proliferative activity of epithelium decreases approximately to an initial level. Histoautoradiographic studies of bioptates of the stomach mucosa obtained under spot gastroscopy in patients suffering from the ulcerous disease allowed to reveal intensifying proliferative activity of epithelium in the ulcer margins. Similar changes in LI were found in gastritis, followed by the gland affection, and in atrophic gastritis.     

Negative effect of iodide on the survival of newly divided epithelial cells in chronically stimulated rat thyroid

The aim of this work was to investigate some aspects of the thyroid epithelial cell kinetics during the iodide-induced involution of a hyperplastic goitre in the rat. Rats were made iodine-deficient for 6 months, and propylthiouracil (PTU) (0.15%) was added to the diet during the last 2 months. Thereafter, rats were refed with iodide and PTU was removed (day 0). Forty-eight hours previously, all the rats were injected with tritiated thymidine ([3H]TdR) (1 microCi/g). Some animals were killed 1 hr or 24 hr after [3H]TdR injection (i.e. on day -2 and -1, day 0 corresponding to the restoration of a normal iodine diet); the other animals were killed after different delay periods and following [3H]TdR injection. Autoradiography of thyroid sections, iodine determination of plasma iodide and protein-bound iodine (PBI), and RIA of plasma thyroid stimulatory hormone (TSH) were performed. Plasma TSH concentration was very high on day 0 of iodide refeeding (3000 +/- 330 ng/ml) and remained at this level until day 8. Plasma PBI was very low on day 0, remained so until day 4 and greatly increased on day 8. Plasma iodide was also very low on day 0, but markedly increased on day 1, then did not vary significantly until day 43 of iodine refeeding. Thyroid weight, elevated on day 0, decreased relatively quickly until day 30, then more slowly until day 73. The [3H]TdR labelling index (LI) of the thyroid epithelial cells (TEC) was high on day 0 (56 +/- 3 labelled cells/10,000 cells), and 24 hr thereafter increased to 104 +/- 3, by division of the labelled cells. On day 1 of iodine refeeding, the LI had abruptly decreased to about half this value and then remained stable for 3 more days. Between day 4 and day 16, a progressive decline in the LI, (by about 3-4 per day), was observed. The LI showed no further modification, up to day 73, the longest period investigated. The decrease in LI occurred without any significant changes in the labelling intensity (grain count) of the remaining labelled cells between day 1 and 16, this indicates that no cell division took place during this period. The data are therefore interpreted as showing a biphasic elimination after iodide refeeding, of cells that were actively proliferating during the goitrous state.(ABSTRACT TRUNCATED AT 400 WORDS)     

Prevention of HCl-ethanol induced gastric mucosal injury in rats by Garcinia cambogia extract and its possible mechanism of action

Oral pretreatment of rats with G. cambogia fruit extract (1 g/kg body weight/day at interval of 7 and 15 days) protected gastric mucosa against HCl-ethanol induced damage by decreasing the volume and acidity of gastric juice. Increased lipid peroxidation, decreased activity of antioxidant enzymes, altered levels of protein and glycoproteins in the ulcerated mucosa, and gastric juice were maintained at near normal levels in G. cambogia pretreated rats. The results suggest the anti-ulcer activity of G. cambogia by virtue of its ability to decrease acidity and increase mucosal defense.     

生长抑素对胃粘膜的保护作用可能与清除自由基有关

本文观察到生长抑素对大鼠冷冻－束缚应激性胃粘膜损伤具有明显的保护作用,同时显著地抑制应激引起的胃粘膜丙二醛含量的升高。应激时大鼠胃粘膜内黄嘌呤氧化酶的生增高,同时谷胱甙肽过氧化物酶的活性降低,但超氧化物歧化酶的活性未见明显变化,生长抑素预处理可使应激时ＧＳＨ－ＰＸ活性的降低恢复到正常水平,但对ＸＯ和ＳＯＤ未见明显影响。上述结果提示,生长抑素对应激性胃粘膜损伤的保护作用似与增强胃粘膜对自由基的清除有     

Gastric mucosal tyrosine kinase activity during aging and its relationship to cell proliferation in rats

The relationship between tyrosine kinase activity and cellular proliferative activity was investigated in the gastric mucosa. For the purpose of comparison, the liver and the pancreas were also included. Groups of 2-, 14- and 22-month-old male Fischer-344 rats were used. Tyrosine kinase activity was determined in the membrane fraction (30,000 x g pellet) utilizing a synthetic polymer, Glu-Tyr (4:1), as substrate. Cellular proliferative activity was assessed by measuring ornithine decarboxylase in the 20,000 x g supernatant. In all age groups, gastric mucosal tyrosine kinase activity was found to be 10-20-fold higher than in the liver or pancreas. In addition, gastric mucosal tyrosine kinase activity in 22-month-old rats was 35-70% higher than in their 2- and 14-month-old counterparts. Gastric mucosal ornithine decarboxylase activity also followed essentially the same pattern as that of tyrosine kinase in that the highest activity was observed in 22-month-old rats. Increased gastric mucosal proliferative activity in 22-month-old rats was also associated with increased tyrosine-phosphorylation of a mucosal membrane protein with an apparent Mr of 53,000. An opposite phenomenon occurred in the pancreas whose proliferative activity was found to be the lowest. It is concluded that the age-associated changes in gastric mucosal proliferative activity are accompanied by parallel alterations in tyrosine kinase activity. Tyrosine-phosphorylation of a 53 kDa membrane protein may play a role in the regulation of cell proliferation.     

Immunoreactivities for epidermal growth factor (EGF) and for EGF receptors in rats with gastric ulcers

Summary The present study was aimed at assessing whether epidermal growth factor (EGF) and its receptors are present in the gastric mucosa during the healing of gastric ulcers. Immunohistochemical, immunochemical and functional studies were performed in rats after induction of ulcers in the oxyntic mucosa. Controls, which included non-operated and sham-operated animals, displayed only rare cells in the bottom of the oxyntic glands showing EGF-like immunoreactivity. Within one day after ulcer induction, a markedly increased number of chief cells in undamaged mucosa showed intense staining. Concomitantly, there was an increased immunoreactivity for EGF receptors in the mucous neck cells. Maximal immunostaining for both compounds was observed at 3 days after ulcer induction; augmented staining was still demonstrable after 3 weeks. RIA revealed significantly increased EGF concentration in the oxyntic mucosa three days after ulcer induction, and at this stage stimulated gastric acid secretion, measured in a parallel group of chronic fistula rats, indicated significant inhibition. The transient increases in EGF-like and EGF receptor immunoreactivities may stimulate gland cell proliferation. The local release of EGF-like substances may also serve to reduce gastric acidity and thereby promote ulcer healing.     

Effects of all-trans retinol and cigarette smoke condensate on hamster tracheal epithelium in organ culture. I. A cell proliferation study

The effects of cigarette smoke condensate (CSC) and all-trans retinol on the cell proliferative activity of vitamin A-deprived hamster tracheal epithelium have been studied in vitamin A-deficient, serum-free, hormone-supplemented medium in organ culture. In the absence of retinol, CSC induced a dose-dependent increase in labeling index (LI) during 12 days of culture. The basal cells were more sensitive to CSC exposure than non-basal cells during the first 6 to 8 culture days. However, in squamous metaplastic foci developing after culture day 6, both basal and non-basal cells in the mid-part of the epithelium were labeled. Physiological concentrations of all-trans retinol stimulated the non-basal LI and inhibited the basal cell LI. Compared with dimethylsulfoxide (DMSO), all retinol concentrations used in the present study inhibited the basal cell LI at each time point examined (4-12 days culture). Exposure of tracheal rings to retinol, either before or after exposure to CSC, or simultaneous exposure to retinol and CSC, clearly decreased the CSC-induced basal cell proliferative activity depending on the retinol concentration used. It is concluded from the present study that squamous metaplasia induced by vitamin A-deficiency or by CSC originates mainly from basal cells and that for the maintenance of these lesions, both basal and non-basal cells play a role. Furthermore, all-trans retinol inhibited CSC-induced basal cell proliferation.