How does brief guided mindfulness meditation enhance empathic concern in novice meditators?: A pilot test of the suggestion hypothesis vs. the mindfulness hypothesis.

Despite the widespread popularity of mindfulness meditation for its various benefits, the mechanism underlying the meditation process has rarely been explored. Here, we present two preliminary studies designed to test alternative hypotheses: whether the effect of brief guided mindfulness meditation on empathic concern arises from verbal suggestion (suggestion hypothesis) or as a byproduct of an induced mindfulness state (mindfulness hypothesis). Study 1 was a pilot randomized control trial of sitting (breath-and-body) meditation vs. compassion meditation that provided preliminary support for the mindfulness hypothesis. Study 2 was set up to rule out the possibility that the meditation effects observed in Study 1 were the effects of repeated measures. An inactive control group of participants underwent the repeated measures of empathic concern with no meditation in between. The pre-post comparison demonstrated no significant changes in the measures. Thus, the results of two studies supported the mindfulness hypothesis. Limitations of the present study and future research directions are discussed.

Real-world Evidence of Diffusion-weighted Imaging Combined With Magnetic Resonance Cholangiopancreatography for Pancreatic Tumor Screening: A Cross-Sectional Diagnostic Accuracy Study.

OBJECTIVES: The aim was to clarify the sensitivity and specificity of diffusion-weighted imaging, as well as of that in combination with magnetic resonance cholangiopancreatography for pancreatic tumor diagnosis in real-world clinical setting. METHODS: Subjects were 217 consecutive patients who underwent both magnetic resonance imaging and contrast-enhanced ultrasound sonography. Cases positive for a pancreatic tumor were confirmed based on pathological diagnosis, whereas negative cases were defined when no solid pancreatic tumor was detected by contrast-enhanced ultrasound sonography or a solid mass was detected but the diagnosis was ultimately denied based on pathological results. Diffusion-weighted imaging-positive was defined as a case with high signals and magnetic resonance cholangiopancreatography-positive when localized main pancreatic duct stenosis with caudal dilation was detected.We calculated sensitivity and specificity of each modality and those in combination based on sequential use for pancreatic tumor diagnosis. RESULTS: Diffusion-weighted imaging showed a sensitivity of 94.4% and specificity of 94.5%, whereas those values for magnetic resonance cholangiopancreatography alone were 83.3% and 99.0%, respectively, and for the modalities in combination were 100% and 94.5%, respectively. CONCLUSIONS: Diffusion-weighted imaging was more sensitive than magnetic resonance cholangiopancreatography, whereas those used in combination resulted in increased sensitivity.

The Relationship Between Polypharmacy and Hospital-stay Duration: A Retrospective Study.

Background There have been very few studies on the association of polypharmacy with clinical course. In this paper, we seek to evaluate the relationship between polypharmacy and hospitalization period. Methods We retrospectively analyzed 322 patients hospitalized from February to September 2017, after excluding short-term and orthopedic cases. Patients with polypharmacy were defined as those who were prescribed more than five drugs at the time of admission. The primary endpoint for all subjects regardless of polypharmacy was the hospitalization period. Using Mann-Whitney U test results, we compared the average number of hospital days between patients with and without polypharmacy. Secondary endpoints were hospitalization period with and without polypharmacy for each disease type. Results The hospitalization period was significantly extended for patients with polypharmacy as compared to those without (31.6 vs. 23.2 days, p: 0.002). Those with an infection had significantly longer hospitalization than those without polypharmacy (27.6 vs. 18.1 days, p: 0.007). Malignancy, heart disease, and cerebrovascular disease did not have a significant effect on hospitalization regardless of polypharmacy. Conclusion Polypharmacy is related to an extended hospitalization period and is found to occur more frequently in patients hospitalized for an infection.

Determinants of High-School Dropout: A Longitudinal Study in a Deprived Area of Japan.

BACKGROUND: Our objective in this study was to find determinants of high-school dropout in a deprived area of Japan using longitudinal data, including socio-demographic and junior high school-period information. METHODS: We followed 695 students who graduated the junior high school located in a deprived area of Japan between 2002 and 2010 for 3 years after graduation (614 students: follow-up rate, 88.3%). Multivariable log-binomial regression models were used to calculate the prevalence ratios (PRs) for high-school dropout, using multiple imputation (MI) to account for non-response at follow-up. RESULTS: The MI model estimated that 18.7% of students dropped out of high school in approximately 3 years. In the covariates-adjusted model, three factors were significantly associated with high-school dropout: ≥10 days of tardy arrival in junior high school (PR 6.44; 95% confidence interval [CI], 1.69-24.6 for "10-29 days of tardy arrival" and PR 8.01; 95% CI, 2.05-31.3 for "≥30 days of tardy arrival" compared with "0 day of tardy arrival"), daily smoking (PR 2.01; 95% CI, 1.41-2.86) and severe problems, such as abuse and neglect (PR 1.66; 95% CI, 1.16-2.39). Among students with ≥30 days of tardy arrival in addition to daily smoking or experience of severe problems, ≥50% high-school dropout rates were observed. CONCLUSIONS: Three determinants of high-school dropout were found: smoking, tardy arrival, and experience of severe problems. These factors were correlated and should be treated as warning signs of complex behavioral and academic problems. Parents, educators, and policy makers should work together to implement effective strategies to prevent school dropout.

Intrahepatic Cholangiolocellular and Cholangiocellular Carcinoma - Differences in the 18F-FDG PET/CT Findings.

Cholangiolocellular carcinoma is a minor primary cancerous tumor of the liver and its coexistence with intrahepatic cholangiocarcinoma in the liver is rare. We herein report a case of concurrent cholangiolocellular carcinoma and intrahepatic cholangiocarcinoma in the liver, in addition to a rectal G1 neuroendocrine tumor, a so-called carcinoid. The intrahepatic tumors showed a different uptake in the 18F-fluoro-2-deoxyglucose (FDG) positron-emission tomography (PET)/computed tomography (CT) findings. In addition to conventional dynamic contrast-enhanced CT, we concluded that FDG PET/CT could therefore be a helpful modality to identify the properties of both cholangiolocellular carcinoma and intrahepatic cholangiocarcinoma.

Determinants of participation in prostate cancer screening: a simple analytical framework to account for healthy-user bias.

In Japan at present, fecal occult blood testing (FOBT) is recommended for cancer screening while routine population-based prostate-specific antigen (PSA) screening is not. In future it may be necessary to increase participation in the former and decrease it in the latter. Our objectives were to explore determinants of PSA-screening participation while simultaneously taking into account factors associated with FOBT. Data were gathered from a cross-sectional study conducted with random sampling of 6191 adults in Osaka city in 2011. Of 3244 subjects (return rate 52.4%), 936 men aged 40-64 years were analyzed using log-binomial regression to explore factors related to PSA-screening participation within 1 year. Only responders for cancer screening, defined as men who participated in either FOBT or PSA-testing, were used as main study subjects. Men who were older (prevalence ratio [PR] [95% confidence interval (CI)] = 2.17 [1.43, 3.28] for 60-64 years compared with 40-49 years), had technical or junior college education (PR [95% CI] = 1.76 [1.19, 2.59] compared with men with high school or less) and followed doctors' recommendations (PR [95% CI] = 1.50 [1.00, 2.26]) were significantly more likely to have PSA-screening after multiple variable adjustment among cancer-screening responders. Attenuation in PR of hypothesized common factors was observed among cancer-screening responders compared with the usual approach (among total subjects). Using the analytical framework to account for healthy-user bias, we found three factors related to participation in PSA-screening with attenuated association of common factors. This approach may provide a more sophisticated interpretation of participation in various screenings with different levels of recommendation.

Individualized and institutionalized residential place-based discrimination and self-rated health: a cross-sectional study of the working-age general population in Osaka city, Japan.

BACKGROUND: Several studies have reported that individualized residential place-based discrimination (PBD) affects residents' health. However, studies exploring the association between institutionalized PBD and health are scarce, especially in Asian countries including Japan. METHODS: A cross-sectional study was conducted with random two-stage sampling of 6191 adults aged 25-64 years in 100 census tracts across Osaka city in 2011. Of 3244 respondents (response rate 52.4%), 2963 were analyzed using multilevel logistic regression to examine the association of both individualized and institutionalized PBD with self-rated health (SRH) after adjustment for individual-level factors such as socioeconomic status (SES). An area-level PBD indicator was created by aggregating individual-level PBD responses in each tract, representing a proxy for institutionalized PBD, i.e., the concept that living in a stigmatized neighborhood affects neighborhood health. 100 tracts were divided into quartiles in order. The health impact of area-level PBD was compared with that of area-level SES indicators (quartile) such as deprivation. RESULTS: After adjustment for individual-level PBD, the highest and third area-level PBD quartiles showed odds ratio (OR) 1.57 (95% credible interval: 1.13-2.18) and 1.38 (0.99-1.92), respectively, for poor SRH compared with the lowest area-level PBD quartile. In a further SES-adjusted model, ORs of area-level PBD (highest and third quartile) were attenuated to 1.32 and 1.31, respectively, but remained marginally significant, although those of the highest area-level not-home-owner (census-based indicator) and deprivation index quartiles were attenuated to 1.26 and 1.21, respectively, and not significant. Individual-level PBD showed significant OR 1.89 (1.33-2.81) for poor SRH in an age, sex, PBD and SES-adjusted model. CONCLUSION: Institutionalized PBD may be a more important environmental determinant of SRH than other area-level SES indicators such as deprivation. Although it may have a smaller health impact than individualized PBD, attention should be paid to invisible and unconscious aspects of institutionalized PBD to improve residents' health.

Geographically-based discrimination is a social determinant of mental health in a deprived or stigmatized area in Japan: a cross-sectional study.

Perceived discrimination has been shown to be associated with health. However, it is uncertain whether discrimination based on geographical place of residence (geographically-based discrimination), such as Buraku or Nishinari discrimination in Japan, is associated with health. We conducted a cross-sectional study (response rate = 52.3%) from February to March 2009 in a Buraku district of Nishinari ward in Osaka city, one of the most deprived areas in Japan. We implemented sex-stratified and education-stratified multivariate regression models to examine the association between geographically-based discrimination and two mental health outcomes (depressive symptoms and diagnosis of mental illness) with adjustment for age, socioeconomic status, social relationships and lifestyle factors. A total of 1994 persons aged 25-79 years (928 men and 1066 women) living in the district were analyzed. In the fully-adjusted model, perceived geographically-based discrimination was significantly associated with depressive symptoms and diagnosis of mental illness. It was more strongly associated among men or highly educated people than among women or among less educated people. The effect of geographically-based discrimination on mental health is independent of socioeconomic status, social relationship and lifestyle factors. Geographically-based discrimination may be one of the social determinants of mental health.

Fatty acid synthase expression in Barrett's esophagus: implications for carcinogenesis.

GOALS: To investigate the relationship between fatty acid synthase (FASN) expression and the clinicopathological characteristics of Barrett's esophagus and its carcinogenesis. BACKGROUND: FASN, a key enzyme of the fatty acid biosynthetic pathway, is overexpressed not only in various types of cancer, but also in premalignant conditions. Therefore, FASN overexpression is considered to be indicative of a possible premalignant stage. STUDY: Patients (N=354) with endoscopically and histologically proven Barrett's esophagus were enrolled. Mucin phenotyping of Barrett's esophagus, expression of FASN and COX-2, cellular proliferation, and apoptosis were evaluated immunohistochemically in biopsy samples, and factors influencing FASN expression were determined by multivariate logistic regression analysis. To evaluate if gastric reflux induces FASN expression, esophageal adenocarcinoma cells were treated with bile acid and low pH, and the effect of a FASN inhibitor on cell proliferation was assessed. RESULTS: Expression of FASN protein was observed in 52.2% of patients with Barrett's esophagus by immunohistochemistry; this expression pattern was retained in esophageal adenocarcinoma. Intestinal mucin phenotype, COX-2, increased stromal angiogenesis, and elevated proliferating cell nuclear antigen index were confirmed to be positive independent factors for FASN expression. In the esophageal adenocarcinoma cell line SEG-1, FASN mRNA was induced by bile acid with low pH. Cell proliferation was strongly suppressed by the FASN inhibitor C75. CONCLUSIONS: FASN is strongly expressed in the intestinal mucin phenotype of Barrett's esophagus, in which Barrett's glandular cells display elevated cellular proliferation, angiogenesis, and COX-2 expression. Exposure of the lower esophagus to bile acid with low pH may induce FASN in Barrett's esophagus.

Exacerbation of indomethacin-induced small intestinal injuries in Reg I-knockout mice.

Nonsteroidal anti-inflammatory drug (NSAID)-induced small intestinal injuries are serious clinical events and a successful therapeutic strategy is difficult. Regenerating gene (Reg) I protein functions as a regulator of cell proliferation and maintains intercellular integrity in the small intestine. The aim of this study was to evaluate the role of Reg I in NSAID-induced small intestinal injuries. First, to examine the effect of Reg I deficiency on such injuries, indomethacin, a widely used NSAID, was injected subcutaneously into 10-wk-old male Reg I-knockout (Reg I(-/-)) and wild-type (Reg I(+/+)) mice twice with an interval of 24 h, after which the mice were euthanized. Small intestinal injuries were assessed by gross findings, histopathology, and contents of IL-1beta and MPO in the experimental tissues. Next, we investigated the therapeutic potential of Reg I in indomethacin-induced small intestinal injuries. Recombinant Reg I protein (rReg I) was administered to 10-wk-old male ICR mice, then indomethacin was administered 6 h using the same protocol as noted above, after which small intestinal injuries were assessed after euthanasia. Our results showed that Reg I(-/-) mice had a greater number of severe small intestinal lesions after indomethacin administration. Histological examinations of the small intestines from those mice revealed deep ulcers with prominent inflammatory cell infiltration, whereas the mucosal content of proinflammatory agents was also significantly increased. In addition, rReg I administration inhibited indomethacin-induced small intestinal injuries in ICR mice. In conclusion, Reg I may be useful as a therapeutic agent in NSAID-induced small intestinal injuries.

Fibroblast-derived HB-EGF promotes Cdx2 expression in esophageal squamous cells.

The molecular basis of attaining columnar phenotype in Barrett's esophagus is poorly understood. One hypothesis states that factors locally produced by cells of mesenchymal origin in chronic reflux esophagitis induce metaplastic transformation. This study was performed to elucidate the factors secreted from fibroblasts that cause columnar phenotype in adjacent squamous epithelium. Human fibroblast cells were exposed to acidified medium for 20 min, followed by medium neutralization for 2 h, and then total RNA was hybridized to Sentrix Human-6 Expression BeadChips. Furthermore, esophageal mucosal biopsy specimens from reflux esophagitis patients were examined for HB-EGF expression using immunohistochemistry. In addition, cells from the human esophageal squamous epithelial cell line HET1A were treated with recombinant HB-EGF, and changes in expressions of Cdx2 and columnar markers were analyzed. The gene expression profile revealed significant upregulation of a variety of growth factors and inflammatory chemokines in response to acid exposure. Among them, HB-EGF was upregulated more than 10-fold. Biopsy specimens from reflux esophagitis patients showed a strong expression of HB-EGF in fibroblast cells underlying the damaged epithelium. Furthermore, in vitro stimulation of HET1A cells with HB-EGF increased Cdx2 in dose-dependent manners. Functional analysis of human Cdx2 promoter also revealed its upregulation by HB-EGF stimulation, showing the role of potential responsive elements (AP-1 and NF-kappaB) for its transcriptional activation. Moreover, the columnar markers cytokeratin 7 and villin were also upregulated by HB-EGF stimulation. HB-EGF induces several genes characteristics of columnar phenotypes of esophageal squamous epithelium in a paracrine manner.

In vivo evidence for the role of RegI in gastric regeneration: transgenic overexpression of RegI accelerates the healing of experimental gastric ulcers.

On the basis of its temporal and spatial pattern of expression during the healing of gastric ulcers, RegI is implied to be a key growth factor governing the gastric progenitor cell proliferation, which is fundamental for reconstruction of the gastric tissue; however, there is no direct in vivo evidence. The aim of this study was to use RegI-transgenic (Tg) mice to test the role of RegI protein in the healing of experimentally induced gastric ulcers. The stomachs from 48 pairs of wild-type (Wt) and Tg littermates were examined for gastric erosions after 24 h of water-immersion stress, or, 6, 12, 18 and 24 h after oral administration of HCl/ethanol. Expression levels of c-fos and c-myc proto-oncogenes were examined over time by real-time reverse transcriptase PCR to assess gastric cell proliferation. Almost all the littermate pairs tested showed superiority of Tg mice over Wt mice in the ability of decreasing ulcer index (UI) (cumulative length of erosion). The time-course study revealed that the UIs of Tg were lower in the healing phase, and not in the injury phase. The fraction of proliferating cells was higher in Tg mice than in Wt mice throughout the time course as assessed by c-fos expression levels. This is the first in vivo evidence that RegI has a role in gastric ulcer healing. We suggest that RegI exerts its effects by promoting growth and not by cytoprotection.

Unsedated transnasal small-caliber esophagogastroduodenoscopy in elderly and bedridden patients.

AIM: To evaluate the safety of unsedated transnasal small-caliber esophagogastroduodenoscopy (EGD) for elderly and critically ill bedridden patients. METHODS: One prospective randomized comparative study and one crossover comparative study between transnasal small-caliber EGD and transoral conventional EGD was done (Study 1). For the comparative study, we enrolled 240 elderly patients aged > 65 years old. For the crossover analysis, we enrolled 30 bedridden patients with percutaneous endoscopic gastrostomy (PEG) (Study 2). We evaluated cardiopulmonary effects by measuring arterial oxygen saturation (SpO(2)) and calculating the rate-pressure product (RPP) (pulse rate x systolic blood pressure/100) at baseline, 2 and 5 min after endoscopic intubation in Study 1. To assess the risk for endoscopy-related aspiration pneumonia during EGD, we also measured blood leukocyte counts and serum C-reactive protein (CRP) levels before and 3 d after EGD in Study 2. RESULTS: In Study 1, we observed significant decreases in SpO(2) during conventional transoral EGD, but not during transnasal small-caliber EGD (0.24% vs -0.24% after 2 min, and 0.18% vs -0.29% after 5 min, P = 0.034, P = 0.044). Significant differences of the RPP were not found between conventional transoral and transnasal small-caliber EGD. In Study 2, crossover analysis showed statistically significant increases of the RPP at 2 min after intubation and the end of endoscopy (26.8 and 34.6 vs 3.1 and 15.2, P = 0.044, P = 0.046), and decreases of SpO(2) (-0.8% vs -0.1%, P = 0.042) during EGD with transoral conventional in comparison with transnasal small-caliber endoscopy. Thus, for bedridden patients with PEG feeding, who were examined in the supine position, transoral conventional EGD more severely suppressed cardiopulmonary function than transnasal small-caliber EGD. There were also significant increases in the markers of inflammation, blood leukocyte counts and serum CRP values, in bedridden patients after transoral conventional EGD, but not after transnasal small-caliber EGD performed with the patient in the supine position. Leukocyte count increased from 6053 +/- 1975/L to 6900 +/- 3392/L (P = 0.0008) and CRP values increased from 0.93 +/- 0.24 to 2.49 +/- 0.91 mg/dL (P = 0.0005) at 3 d after transoral conventional EGD. Aspiration pneumonia, possibly caused by the endoscopic examination, was found subsequently in two of 30 patients after transoral conventional EGD. CONCLUSION: Transnasal small-caliber EGD is a safer method than transoral conventional EGD in critically ill, bedridden patients who are undergoing PEG feeding.

Does gastroesophageal reflux have an influence on bleeding from esophageal varices?

BACKGROUND: Mucosal breaks induced by gastroesophageal reflux of gastric contents were more frequently found on the right anterior wall of the lower esophagus. Bleeding from esophageal varices may be also derived from gastroesophageal reflux. The circumferential location of the ruptured esophageal varices was evaluated to elucidate the relationship between gastroesophageal reflux and variceal rupture. METHODS: Between January 2004 and December 2006, 26 patients who had primary bleeding from esophageal varices and 74 patients without evidence of bleeding with positive red color signs on varices were enrolled in this study retrospectively. Locations of bleeding spots and nonbleeding red color signs of esophageal varices were retrospectively evaluated by endoscopic photographs, and the relationship between the location of red color signs and the risk of bleeding was evaluated. Other possible predictors for bleeding were also investigated by multivariate regression analysis. RESULTS: Red color signs were frequently found in the right posterior wall of the lower esophagus. However, bleeding spots of esophageal varices were more frequently seen in the right anterior side (64.0%) than in others. The positive predictor for bleeding from esophageal varices was the presence of red color sign in the right anterior wall of the esophagus, and the administration of proton pomp inhibitor was the negative predictor. CONCLUSIONS: Gastroesophageal acid reflex may be a risk factor of bleeding from esophageal varices. Attention should be paid to the circumferential location of red color signs in endoscopic screening of patients with esophageal varices to predict future bleeding.

Which landmark results in a more consistent diagnosis of Barrett's esophagus, the gastric folds or the palisade vessels?

BACKGROUND: The endoscopic landmark used to diagnose Barrett's esophagus differs between Japanese and Western endoscopists. OBJECTIVE: To compare the degree of diagnostic variation in results achieved by Japanese endoscopists when using the palisade vessels as a landmark of the distal esophagus and when using the gastric folds; interobserver diagnostic concordance was evaluated. DESIGN: Eighty-four endoscopists classified 30 patients with Barrett's esophagus by viewing projected endoscopic photographs. The endoscopists were asked to identify the distal end of the esophagus, first by using the Japanese criteria and later by using the gastric folds after an explanation of the Prague C&M Criteria. Endoscopists were divided into groups according to years in practice as an endoscopist, presence or absence of board certification from the Japan Gastroenterological Endoscopy Society, and whether they had taken any special endoscopic training courses on GERD. The kappa coefficient of reliability was calculated for each group. RESULTS: The initial overall kappa value for all the endoscopists for the identification of the distal end of the esophagus was only 0.14, an unacceptably low value of concordance over and above chance agreement. The length of experience with diagnostic endoscopy, board license, or special training had no impact on the level of concordance. After an explanation of the C&M Criteria, however, there was a statistically significant improvement in the diagnostic concordance. CONCLUSIONS: The upper end of the gastric folds, as used in C&M Criteria, may be a more suitable landmark than the palisade vessels for identifying the distal end of the esophagus by endoscopy.

Prevalence of and risk factors for Barrett's esophagus with intestinal predominant mucin phenotype.

OBJECTIVE: Barrett's esophagus with the intestinal predominant mucin phenotype is considered to have a higher malignant potential than that with the gastric predominant mucin phenotype. The purpose of this prospective study was to investigate the prevalence of and risk factors for Barrett's esophagus with the intestinal predominant mucin phenotype in patients undergoing endoscopy. MATERIAL AND METHODS: A total of 1699 consecutive patients undergoing esophagogastroduodenoscopy were enrolled in the study. A targeted biopsy was performed when endoscopically observed columnar-appearing esophagus was stained with crystal violet. The sample, histologically evidenced as Barrett's esophagus, was immunohistochemically evaluated and categorized as of either gastric or intestinal predominant mucin phenotype. All the patients were requested to complete the structured questionnaire indicating their symptoms and food consumption patterns. Prevalence of and risk factors for Barrett's esophagus with and without the intestinal predominant mucin phenotype were investigated. RESULTS: Out of 1668 patients, 629 (37.7%) were found to have endoscopic Barrett's esophagus. In 333 out of 1668 patients (19.9%), histological studies were diagnostic of Barrett's esophagus. One hundred and six of these 333 patients (31.8%) had the intestinal predominant mucin phenotype. Age, male gender and the presence of hiatal hernia were confirmed by multivariate analysis as the independent predictors for the presence of Barrett's esophagus with the intestinal predominant mucin phenotype. CONCLUSIONS: Barrett's esophagus with the intestinal predominant mucin phenotype was immunohistochemically found in 6.4% of all study patients. Older age, male gender and the presence of hiatal hernia were the risk factors for the presence of Barrett's esophagus with the intestinal predominant mucin phenotype.

Transgenic overexpression of Reg protein caused gastric cell proliferation and differentiation along parietal cell and chief cell lineages.

Reg (regenerating gene product) was originally identified as a growth factor involved in pancreatic regeneration. During the healing course of gastric erosion, Reg expression is highly increased in the enterochromaffin-like (ECL) cells surrounding the ulcer crater, suggesting its role as a regulator of gastric mucosal regeneration. However, there has been no direct in vivo evidence of a growth-promoting role of Reg for the gastric mucosal cells. In the current study, Reg-transgenic mice were created and gastric mucosa were analysed for histological changes. Transgenic mice showed a marked increase in the thickness of the fundic mucosa. Anti-proliferating cell nuclear antigen (PCNA) staining of the fundic mucosa demonstrated the enlargement of the proliferating neck zone and the lower PCNA-negative zone. Histological analysis employing antibodies against cell-type markers revealed expansion of the chief cell and parietal cell populations and no change in the number of surface mucus-producing cells, ECL cells, or G cells. In conclusion, Reg has a growth-promoting effect on gastric progenitor cells and an activity to direct the differentiation of the cells into chief cell and parietal cell lineages. This was in contrast to other factors, all of which had been shown to drive differentiation towards mucus producing cells in vivo. In the injured gastric mucosa, Reg may play a unique and important part in the reconstruction of the properly organized mucosal architecture.