[Risk factors for recurrent hospitalizations of patients with atrial fibrillation].

Objective: To determine the predictors of recurrent hospitalizations among atrial fibrillation (AF) patients. Methods: We analyzed data from the Chinese Atrial Fibrillation Registry (CAFR), a prospective cohort study involving non-valvular atrial fibrillation (NVAF) patients from Augest 2011 to December 2017. A total of 5 349 NVAF patients with a minimum of 48 months follow-up were included for analysis. Data including patient demographics, complications, medical and ablation history were collected. The maximum number of all-cause hospitalizations within one-year for each patient served as the primary endpoint. Patients hospitalized less than twice within one-year were defined as non-recurrent hospitalizations group, those hospitalized at least twice within one-year were definned as recurrent hospitalizations group. Logistic regression model was used to identify associated risk factors for recurrent hospitalizations. Results: Of 5 349 NVAF patients, those hospitalized for 0, 1, 2, 3, 4 and at least 5 times within one-year was 2 703 (50.5%), 1 776 (33.2%), 642 (12.0%), 161(3.0), 52 (1.0%), 15 (0.3%), respectively. Eight hundred and seventy (16.3%) patients were included in recurrent hospitalizations group, 4 479 (83.7%) patients were included in non-recurrent hospitalizations group. Compare with non-recurrent hospitalizations group, patients in recurrent hospitalizations group was more likely to be older and female, more frequently had a history of hypertension, heart failure, coronary heart disesase, ischaemic stroke/transient ischaemic attack, diabetes mellitus, peptic ulcer, a AF duration for more than 1 year, medication including drugs for ventricular rate control, statin, angiotensin-converting enzyme inhibitors (ACEI)/angiotensin receptor blocker (ARB) and higher CHA(2)DS(2)-VASc scores (P<0.05), but less frequently had higher education, a history of drinking, smoking and ablation (P<0.05). Multivariable analysis showed that age 50-64 (OR=1.47, 95%CI 1.20-1.80), age≥65 (OR=1.89, 95%CI 1.50-2.38), female (OR=1.21, 95%CI 1.01-1.46), hypertension history (OR=1.42, 95%CI 1.16-1.74), heart failure history (OR=1.73, 95%CI 1.37-2.18), coronary heart disease history (OR=1.63, 95%CI 1.31-2.03), peptic ulcer history (OR=2.00, 95%CI 1.18-3.39) were independent risk factors for recurrent hospitalizations, while higher education (college or above) (OR=0.82, 95%CI 0.69-0.99) was the protective factor for recurrent hospitalizations. Conclusions: Nearly 1 in 6 of AF patients were admitted to hospital more than once within one year in this NVAF cohort. Age≥50, female, hypertension history, heart failure history, coronary heart disease history, peptic ulcer history are associated with an increased risk of recurrent hospitalizations.

[The thromboembolism risk of low-risk atrial fibrillation patients with different clinical characteristics].

Objective: This study explored the thromboembolism risk of low-risk atrial fibrillation (AF) patients (CHA2DS2-VASc score of 0 or 1 for male and 1 or 2 for female) with different clinical characteristics to provide the basis for anticoagulation decision-making in these patients. Methods: We prospectively enrolled consecutive 2 862 nonvalvular low-risk AF patients between August 2011 to December 2018 in China-AF (China Atrial Fibrillation Registry) Study, their CHA2DS2-VASc score was 0 or 1 for male and 1 or 2 for female. According to their age, sex, presence or absence of hypertension, diabetes mellitus, congestive heart failure, and vascular disease at the time of enrolling, patients were divided into CHA2DS2-VASc score 0 score group, 1 score group, and 2 score group. Patients were followed up every 6 months by outpatient clinic visit or telephone interview. The outcome was a thromboembolic event, including ischemic stroke and systemic embolism. Univariate Cox regression analysis was used to compare the thromboembolism risk between the patients with different risk factors and CHA2DS2-VASc score 0 group. Results: A total of 2 862 low-risk atrial fibrillation patients were enrolled in this study. 915 patients (32.0%) were female, and age was (55.0±10.7) years old. There were 933 patients (32.6%) in CHA2DS2-VASc score 0 group, 1 401 patients (49.0%) in score 1 group and 528 patients (18.5%) in score 2 group. During follow-up (median 1.5 years, 5 811.82 person-years), 33 cases of thromboembolic events were recorded, the annual rate of thromboembolism was 0.57% (95%CI 0.40%~0.80%). The number of thromboembolic events in patients with CHA2DS2-VASc score 0, 1 and 2 were 8, 11 and 14, respectively, and the annual thromboembolism event rates were 0.40% (95%CI 0.20%-0.81%), 0.39% (95%CI 0.22%-0.71%) and 1.34% (95%CI 0.80%-2.27%), respectively. The risk of thromboembolism of CHA2DS2-VASc score 2 group (HR=3.53, 95%CI 1.48-8.44; P=0.005), especially female patients aged 65-74 years in CHA2DS2-VASc score 2 group (HR=2.67, 95%CI 1.63-4.38; P<0.000) was significantly higher than that in patients of CHA2DS2-VASc score 0 group. Conclusion: Low-Risk Atrial Fibrillation patients with CHA2DS2-VASc score 2, especially female patients aged 65-74 years old with CHA2DS2-VASc score 2 are at higher risk of thromboembolism in low-risk AF patients. For such patients, intensified oral anticoagulant therapy might be helpful to reduce the risk of thrombolism.

[Clinical and imaging features of acute histoplasmosis].

Objective: To investigate the clinical and imaging characteristics of acute histoplasmosis. Methods: The clinical and imaging data of 10 patients with acute histoplasmosis were studied. Their clinical and imaging characteristics were analyzed. All the patients returned from a South American republic in April 2019 and were treated at the Chongqing public health medical treatment center. Results: All the 10 patients were male, aged 30-56 years old, with an average age of 43.8 years old. Four of them were engaged in soil clearing, 2 in gas cutting, 2 in moving tools, and 2 in inspection. The disease in all the 10 patients was caused by inhaling a large amount of bacteria-bearing dust in a short time, with an incubation period of 9-13 days, and the main clinical manifestations were fever, insomnia, dizziness, headache, cough, poor appetite, rash and diarrhea. One patient's head CT showed extensive thickening and increased density of bilateral frontotemporal, parietal and occipital meninges, while the other 9 patients showed no obvious abnormalities. Chest CT findings were as follows: (1) Multiple nodular shadow: the chest CT findings of 4 patients were miliary nodular shadow with diffuse distribution in both lungs. Most of the nodules were less than 5 mm in diameter and distributed evenly or unevenly. CT findings of 6 cases showed scattered nodular shadows in both lungs, with diameters ranging from 2 to 15 mm, and obvious distribution in subpleural and inferior lobes of both lungs. (2) Consolidation shadow: in 2 cases, the size of the shadow was uneven and the density increased, mainly distributed in the subpleura and the lower lobe of both lungs. (3) Ground glass density shadow: mainly distributed around nodules, halo signs can be seen around some nodules. (4) Mediastinum and/or hilar lymph nodes were enlarged. (5) Pleural effusion: a small amount of pleural effusion was found in 4 cases. (6) Pericardial effusion in 3 cases. Abdominal CT showed splenomegaly in 8 cases and hepatomegaly in 1 case. Conclusions: Acute histoplasmosis has no specificity in clinical manifestations. However, there are still some features in CT manifestations, including multiple nodules in both lungs accompanied by halo, enlarged liver, spleen and mediastinal lymph nodes, and multiple serous cavity effusions.

[Association between weight control and recurrence of atrial fibrillation after catheter ablation in overweight and obese patients].

Objectives: This study explored the relationship between weight control and atrial fibrillation (AF) recurrence after catheter ablation in overweight and obese patients. Methods: We prospectively enrolled consecutive 333 overweight and obese patients aged 28 to 87 years old, who underwent catheter ablation for AF in Beijing Anzhen Hospital between October 2015 and February 2016. Data of patients' characteristics, laboratory examination and treatment were collected at baseline. Each patient was followed up at 3, 6 and 12 months after ablation to collect information on weight, AF recurrence, stroke, major bleeding, hospitalization for cardiovascular reasons and death, etc. Patients were divided into weight controlled group (ΔBMI<-1 kg/m(2)) and weight uncontrolled group (ΔBMI≥-1 kg/m(2)), according to the changes in the most recent exposure BMI before AF recurrence in patients with recurrence or the BMI at 12 months' follow-up in patients without recurrence and the BMI at baseline. Multivariate logistic regression was performed to adjust other known risk factors of AF recurrence and to explore the association between weight control and AF recurrence after catheter ablation. Results: There were 54 patients in weight controlled group and 279 patients in weight uncontrolled group. There were no significant differences in age, gender, education level, left atrial size and history of hypertension between the two groups (all P>0.05). The proportion of patients using angiotensin-converting enzyme inhibitors/angiotensin receptor blockers was higher in the weight controlled group (50.0%(27/54) vs. 34.8%(97/279), P=0.034). However, there was no significant difference in the proportion of patients with obesity (33.3% (18/54) vs. 29.7% (83/279)), paroxysmal AF (59.3% (32/54) vs. 56.6% (158/279)) and AF duration less than 5 years (76.9% (40/52) vs. 65.4% (178/272)) between the weight controlled group and the uncontrolled group. During 1-year follow-up after ablation, the recurrence rate of AF was significantly lower in the weight controlled group than that in the weight uncontrolled group (14.8% (8/54) vs. 32.6%(91/279), P=0.009). Multivariable logistic regression analysis shows that weight control is independently associated with a lower postoperative AF recurrence rate (OR=0.40, 95%CI 0.18-0.90, P=0.026). Conclusion: Weight control is strongly associated with a lower AF recurrence rate after catheter ablation in overweight and obese patients.

[Correlation between mismatch repair proteins status and clinicopathological characteristics in sporadic colorectal cancer patients].

Objective: To explore the expression of mismatch repair (MMR) proteins in sporadic colorectal cancer (SCRC) patients, and its association with clinicopathological characteristics of SCRC. Methods: Patients with histologically confirmed colorectal cancer were consecutively recruited between December 2011 and June 2015 at Sun Yat-sen University Cancer Center. The exclusion criteria included multiple primary colorectal tumors, hereditary colorectal cancer (including Lynch syndrome, familial adenomatous polyposis), and the patients without the MMR proteins status tested. A total of 2 684 patients were included. Correlations of MMR proteins status and patients' demographics (including gender, age), tumor characteristics (site and differentiation) and TNM staging (excluding 315 SCRC patients receiving neoadjuvant therapy) were investigated. Results: The percentage of deficient MMR (dMMR) in these SCRC patients was 10.2%, and that of proficient MMR (pMMR) was 89.8%. The dMMR was more likely to be detected in younger (≤59 old years) SCRC patients compared to the elderly (>59 years) [12.7%(179/1 406)vs 7.5%(96/1 278), P<0.001]. The dMMR rate in right colon cancer was significantly higher than that in left colon cancer and rectal cancer [22.7%(151/664)vs 7.2%(69/956)vs 5.2%(55/1 064), P<0.001]. Among the various pathological types of SCRC, mucinous adenocarcinoma showed the highest rate of dMMR (24.4%), and neuroendocrine carcinoma the lowest rate of dMMR (0) (P<0.001). In addition, the proportions of dMMR in stage Ⅰ, stage Ⅱ, stage Ⅲ and stage Ⅳ SCRC were 9.7%, 16.5%, 8.5%, and 3.9%, respectively (P<0.001). There is no significant difference in the proportion of dMMR between male and female (11.0% vs 9.1%, P=0.114). Conclusion: dMMR status may be most likely to exist in younger (≤59 years) patients with stage Ⅱ right colon mucinous adenocarcinoma among SCRC.

[Situation of long-term use of oral anticoagulation among atrial fibrillation patients with stroke in different level hospital].

OBJECTIVE: To investigate the current situation, time trends and factors associated with long-term use of oral anticoagulation (OAC) among atrial fibrillation (AF) patients with ischemic stroke. METHODS: We used the dataset from the CAFR (Chinese Atrial Fibrillation Registry), a prospective, multicenter, hospital-based registry study involving 20 tertiary and 12 nontertiary hospitals in Beijing. In brief, 380 consecutive AF patients with following ischemic stroke were enrolled from 2003 to 2014.Patients with valvular AF, radiofrequency catheter ablation history or contraindications of OAC were excluded. We divided the patients into two groups according to hospital level, and investigated the rate of OAC use and its change over time in patients who had indication, the factors including patient characteristics and hospital level associated with OAC use were also analyzed. RESULTS: Overall oral anticoagulation use rate was 27.71%, which dropped to 22.11% and 15.26% at 6 months and 12 months, respectively.A total of 298 participates were enrolled from tertiary hospitals (78.42%), and 82 were enrolled from nontertiary hospitals. The status of OAC use in tertiary hospitals was better than nontertiary hospitals (32.66% vs 7.32%, P<0.001). Multivariable analysis showed better oral anticoagulation use was independently associated with higher-level hospitals (odds ratio 1.785, 95% confidence interval 1.026-3.106, P=0.040), and history of heart failure (odds ratio 2.247, 95% confidence interval 1.235-4.090, P=0.008). CONCLUSIONS: These data indicates oral anticoagulation use has improved in atrial fibrillation patients with stroke in Beijing. The use of anticoagulation among the patients from tertiary hospitals is significantly better than those from nontertiary hospitals, and the history of heart failure may have effect on the use of oral anticoagulation.

Antibody response to GD3 ganglioside is independent of NKT cells.

BACKGROUND: NKT cells recognize glycolipids presented by CD1d on antigen-presenting cells (APC) and have been largely characterized by their ability to be activated by alpha-galactosylceramide, a glycolipid not expressed on mammalian cells. We have shown previously that GD3 can be cross-presented by CD1d to NKT cells and is the first tumor-derived glycolipid recognized by NKT cells. But the ability of NKT cells to modulate B-cell responses to tumor glycolipids that are themselves recognized by NKT cells has not been explored. METHODS: We tested whether NKT cells are required for antibody (Ab) responses to GD3. We immunized wild-type mice, mice deficient in invariant chain NKT cells (iNKT cells) and mice deficient in total NKT cells against GD3. Ab titer against GD3 was measured by ELISA. RESULTS: We found the IgM and IgG responses against GD3 were similar among the three strains of mice, including the IgG isotypes induced. Pre-expanded NKT cells to GD3 did not affect the anti-GD3 Ab response. DISCUSSION: We conclude that Ab responses to GD3 are independent of NKT cells and that strategies to manipulate NKT cells in vivo are not likely to enhance the anti-GD3 Ab response induced by vaccines.

Photocatalytic Degradation of Reactive Brilliant Blue X-BR in Aqueous Solution Using Quantum-sized ZnO.

Quantum-sized ZnO was prepared using sol-gel method with Zinc acetate dehydrate (Zn(CH(3)COO)(2).2H(2)O) and lithium hydroxide monohydrate(LiOH.H(2)O) as raw material. The ZnO particles annealed at different temperature were characterized by means of X-ray diffraction (XRD), Infrared absorption spectroscopy (IR) and UV-Vis spectroscopy. The degradation rate of reactive brilliant blue X-BR in aqueous solution was used to evaluate the photocatalytic performance of the quantum-sized ZnO. The experimental results indicated that the photocatalytic property of the ZnO was excellent. The photocatalytic efficiency of quantum-sized ZnO was significantly influenced by the calcining heat. When calcined at 300(o)C, its size is 6.78 nm and the photocatalytic performance is the best. The degradation rate of reactive brilliant blue X-BR could exceed 90% in 15 min at 35(o)C, when the concentration of the quantum-sized ZnO was 0.35 mg/L.

Comparison of the V1b antagonist, SSR149415, and the CRF1 antagonist, CP-154,526, in rodent models of anxiety and depression.

Vasopressin and corticotropin releasing factor (CRF) are both critical regulators of an animal's stress response and have been linked to anxiety and depression. As such, antagonists of the CRF1 and V1b receptor subtypes are being developed as potential treatments for affective disorders. The two most characterized V1b and CRF1 antagonists are SSR149415 and CP-154,526, respectively, and the present studies were designed to compare these two compounds in acute animal models of affective disorders. We employed five anxiety models: Separation-induced pup vocalizations (guinea pig and rat), elevated plus-maze (EPM), conditioned lick suppression (CLS), and marble burying (mouse); as well as three depression models: forced swim test (FST; mouse and rat) and tail suspension test (TST; mouse). SSR149415 (1-30 mg/kg) was active in the vocalization, EPM and CLS models, but inactive in marble burying. CP-154,526 (1-30 mg/kg) was active in vocalization models, but inactive in EPM, CLS, and marble burying. SSR149415 was inactive in all depression models; CP-154,526 was active in rat FST but inactive in mouse models. This work demonstrates the different profiles of V1b and CRF1 receptor antagonists and supports both approaches in the treatment of affective disorders.

Characterization of the nociceptin receptor (ORL-1) agonist, Ro64-6198, in tests of anxiety across multiple species.

RATIONALE: Previous studies have demonstrated behaviors indicative of anxiolysis in rats pretreated with the nociceptin receptor (opioid receptor like-1, ORL-1) agonist, Ro64-6198. OBJECTIVES: The aim of this study was to examine the effects of Ro64-6198 in anxiety models across three species: rat, guinea pig, and mouse. In addition, the receptor specificity of Ro64-6198 was studied, using the ORL-1 receptor antagonist, J-113397, and ORL-1 receptor knockout (KO) mice. Finally, neurological studies examined potential side effects of Ro64-6198 in the rat and mouse. RESULTS: Ro64-6198 (3-10 mg/kg) increased punished responding in a rat conditioned lick suppression test similarly to chlordiazepoxide (6 mg/kg). This effect of Ro64-6198 was attenuated by J-113397 (10 mg/kg), but not the mu opioid antagonist, naltrexone (3 mg/kg). In addition, Ro64-6198 (1-3 mg/kg) reduced isolation-induced vocalizations in rat and guinea pig pups. Ro64-6198 (3 mg/kg) increased the proportion of punished responding in a mouse Geller-Seifter test in wild-type (WT) but not ORL-1 KO mice, whereas diazepam (1-5.6 mg/kg) was effective in both genotypes. In rats, Ro64-6198 reduced locomotor activity (LMA) and body temperature and impaired rotarod, beam walking, and fixed-ratio (FR) performance at doses of 10-30 mg/kg, i.e., three to ten times higher than an anxiolytic dose. In WT mice, Ro64-6198 (3-10 mg/kg) reduced LMA and rotarod performance, body temperature, and FR responding, but these same measures were unaffected in ORL-1 KO mice. Haloperidol (0.3-3 mg/kg) reduced these measures to a similar extent in both genotypes. These studies confirm the potent, ORL-1 receptor-mediated, anxiolytic-like effects of Ro64-6198, extending the findings across three species. Ro64-6198 has target-based side effects, although the magnitude of these effects varies across species.

miR-625 suppresses tumour migration and invasion by targeting IGF2BP1 in hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is one of the most prevalent malignancies and the third leading cause of cancer-related deaths worldwide. Tumour metastasis is one of the major causes of high mortality. microRNAshave been implicated in HCC metastasis. In this study, we found that miR-625 was frequently downregulated in HCC samples. A decrease in miR-625 was significantly correlated with lymph node anddistance metastasis (P=0.013), the presence of portal venous invasion (P=0.036), tumor-node-metastasis (TNM) stage (P=0.027) and unfavourable overall survival (P=0.003). Compared with primary tumours, miR-625 expression was markedly reduced in portal venous metastatic tumours. Re-expression of miR-625 in HCC cells was remarkably effective in suppressing cell migration andinvasiveness in vitro and in vivo. Mechanistically, miR-625 was confirmed to downregulate IGF2 mRNA-binding protein 1(IGF2BP1) directly, the expression of which was inversely correlated with the level of miR-625 in HCC cell lines and tissues. High expression of IGF2BP1 was frequently found in HCC samples, and associated with poor prognosis. Knockdown of endogenous IGF2BP1 by siRNA exhibited similar effects as the overexpression of miR-625, whereas overexpression of IGF2BP1 (without the 3'-UTR) abrogated miR-625-mediated metastasis inhibition. Interference of the PTEN/HSP27 pathway contributed to miR-625-mediated metastasis inhibition. Taken together, our data suggest that miR-625 might function as an antimetastatic miRNA to have an important role in HCC progression by modulating the IGF2BP1/PTEN pathway. The newly identified miR-625/IGF2BP1 axis represents a new potential therapeutic target for HCC treatment.

Susceptibility to esophageal cancer and genetic polymorphisms in glutathione S-transferases T1, P1, and M1 and cytochrome P450 2E1.

Genetic polymorphisms in enzymes involved in carcinogen metabolism have been shown to influence susceptibility to cancer. Cytochrome P450 2E1 (CYP2E1) is primarily responsible for the bioactivation of many low molecular weight carcinogens, including certain nitrosamines, whereas glutathione S-transferases (GSTs) are involved in detoxifying many other carcinogenic electrophiles. Esophageal cancer, which is prevalent in China, is hypothesized to be related to environmental nitrosamine exposure. Thus, we conducted a pilot case-control study to examine the association between CYP2E1, GSTM1, GSTT1, and GSTP1 genetic polymorphisms and esophageal cancer susceptibility. DNA samples were isolated from surgically removed esophageal tissues or scraped esophageal epithelium from cases with cancer (n = 45), cases with severe epithelial hyperplasia (n = 45), and normal controls (n = 46) from a high-risk area, Linxian County, China. RFLPs in the CYP2E1 and the GSTP1 genes were determined by PCR amplification followed by digestion with RsaI or DraI and Alw26I, respectively. Deletion of the GSTM1 and GSTT1 genes was examined by a multiplex PCR. The CYP2E1 polymorphism detected by RsaI was significantly different between controls (56%) and cases with cancer (20%) or severe epithelial hyperplasia (17%; P < 0.001). Persons without the RsaI variant alleles had more than a 4-6-fold risk of developing severe epithelial hyperplasia (adjusted odds ratio, 6.0; 95% confidence interval, 2.3-16.0) and cancer (adjusted odds ratio, 4.8; 95% confidence interval, 1.8-12.4). Polymorphisms in the GSTs were not associated with increased esophageal cancer risk. These results indicate that CYP2E1 may be a genetic susceptibility factor involved in the early events leading to the development of esophageal cancer.

Side-entry excitation and detection of square capillary array electrophoresis for DNA sequencing.

In high throughput DNA sequencing based on capillary electrophoresis, efficient coupling of the laser to each capillary is a challenge. Our group previously reported two multiple point irradiation schemes. The present work describes a more efficient excitation and detection method in which the laser light propagates through the capillary array without undergoing a serious reduction in power. An array of square capillaries (340 microns O.D. x 75 microns I.D.) was sandwiched between two fused-silica plates with an index-matching solution in between. The light was directed into the channel across the capillary array from the side. DNA sequences of PGEM/U from 24 capillaries were obtained even with a relatively low-power laser. The excitation scheme can be scaled up to hundreds of capillaries to achieve high-speed, high-throughput DNA sequencing, genetic typing and drug screening.

[N-nitrosamines in gastric juice of subjects from high incidence area of esophageal cancer].

A total of 353 samples of gastric juice was collected from Lin-xian subjects who were examined by endoscopy. NDMA, NDEA, NMBzA, Npyr, Npip, NSAR and other unknown compounds were detected in the fasting gastric juice. NMBzA, Npyr, Npip and NSAR can induce esophageal cancer in animals. Among the concentrations of N-Nitrosamines in gastric juice, the level of NDMA was the highest, its mean value 17.09 ppb; the level of NDEA stood next with a mean value of 6.95 ppb; the amounts of NMBzA, Npyr and Npip were 4.77, 2.45 and 1.30 ppb, respectively. A positive correlation was found between the amount of N-Nitrosamines in gastric juice and the various lesions in the esophageal epithelium of the subjects, the amount of N-Nitrosamines in gastric juice from subjects with normal esophageal epithelium was lower than that from subjects with marked dysplasia or carcinoma of esophagus. This finding lends further support to their possible involvement in esophageal cancer development.

[Promoting effect of Roussin red methyl ester (RRME) in the pickled vegetables in Linxian County on the forestomach epithelium of mice].

The promoting effect of Roussin red methyl ester (RRME) identified and isolated in the pickled vegetables from Linxian county, a high incidence area of esophageal cancer, was studied in mice. In the mice fed on RRME alone, no pathological lesions were detected in the esophagus and forestomach. Other mice, intubated with N-methyl-N-benzyl-nitrosamine (NMBzA) for 3 times, were then given gastric doses of RRME. 8 out of 36 mice were found to have papilloma of the forestomach, the incidence of papilloma was 22.2%. By histological examination, 51.7% of grade II precancerous lesions in the epithelium of forestomach was found. One other group of mice was intubated with NMBzA only for 3 times, then followed until the end of experiment. 3 out of 21 mice were found to have papilloma of the forestomach, an incidence of 14.3%. 21.1% of grade II precancerous lesions was found in the epithelium of forestomach. The experimental results show that RRME appears to have a promoting effect on the process of tumorigenesis initiated by NMBzA in the forestomach of mice. The promoting effect of RRME on the multisteps of the development of esophageal cancer in Linxian county is discussed.

[Esophageal carcinoma in human fetus induced by N-methyl-N-benzylnitrosamine (NMBzA)].

Previous studies have suggested that N-nitroso compounds play a causative role. In the present study, human fetal esophageal epithelium was cultured for 3 weeks with NMBzA obtained in Linxian County (a high incidence area of esophageal cancer). Then, the explants were heterotransplanted to mesentery of BALB/c nude mice which were continually fed with NMBzA in drinking water for 8 months. The results showed that in NMBzA-treated mice, a small tumor was found on the mesentery two months after transplantation. The small tumor gradually grew to 2 x 1.8 cm in size 8 months after transplantation. No tumor was observed in control nude mice. Macroscopically, no tumor was seen in the esophagus of nude mice bearing esophageal tumor on mesentery. Pathology of the induced tumor showed squamous cell carcinoma. DNA extracted from the tumor induced by NMBzA was hybridized with Alu sequence using dot blot. Alu sequence was present in the induced tumor, indicating that the tumor is of human origin. This is the first report to confirm that human esophageal carcinoma could be induced by N-nitrosamine. It provides a direct evidence that NMBzA is a causative agent of esophageal cancer in Linxian County.

[Modification of esophageal epithelium DNA in the human fetus by N-nitrosomethylbenzylamine (NMBzA)].

Human fetal esophageal epithelium, after being exposed to NMBzA, was found to contain O6-methyldeoxyguanine (O6-MedG), a NMBzA-modified DNA adduct, in tissue DNA by radioimmunoassay and monoclonal antibody, which is highly specific to O6-MedG. The highest level of O6-MedG was 58.83 pMol/mg DNA after adding 5.0 mM NMBzA in vitro. The level of O6-MedG and the concentration of NMBzA followed the dose-effect relationship. O6-MedG could be eliminated from DNA by normal human fetal esophageal epithelium. About 50% of O6-MedG was cleared away in the first 1-2 hours during the post-treatment incubation, which was followed by a slower phase of elimination with 18% left in 24 hours. The results indicate that the human fetal esophageal epithelium can metabolically activate NMBzA in vitro and form O6-MedG, which, as well known, can cause mutagenesis and carcinogenesis and, hence, may most likely be related to the development of human esophageal cancer.

[Mutation of p53 gene in human cancers of the esophagus and gastric cardia].

p53 gene in human esophageal cancer (EC) and cancer of gastric cardia was analyzed. Southern blotting hybridization revealed that five of 35 of EC sample were found to contain abnormal structure of p53 gene, including 2 deletions and 3 rearrangements; two of 27 adjacent non-tumor tissues also contain abnormal structure of p53 gene (7.4%), among them one case was fragment deletion and another case was rearrangement. PCR-direct sequencing technique was used to detect p53 point mutation within exon and intron 5 through 9. Fifteen of 30(50%) of esophageal squamous cell carcinomas contained mutation of p53 gene. Five of 11(45%) adjacent non-tumor tissues also contained mutation of p53 gene. An esophageal adenocarcinoma showed p53 mutation. Three of 4 carcinoma of gastric cardia showed p53 mutation. Mutation spectrum in EC: 8 of 22 cases (36.4%) of p53 mutation were G:C to A: T transition, 6 of 22 cases (27.3%) of p53 mutation were frameshift mutation, including 13.6% (3/22) insertion and 9.1% (2/22) deletion mutation. Some new sites of p53 mutation in human EC were identified. The results suggest that the p53 gene plays an important role in carcinogenesis of human esophagus and gastric cardia.

[Effect of copper and zinc on the metabolism of N-nitrosamine and the activity of cytochrome P-450 in the liver of rats].

The effect of copper and zinc on the metabolism of N-nitrosamine and activity of cytochrome P-450 in the liver of rats was studied. Copper and zinc enhanced obviously the activity of cytochrome P-450 in the liver. The level of cytochrome P-450 in the liver of control rats was 0.64 nmol/mg protein but that in the liver of rats treated with copper or zinc was 1.31 and 1.17 nmol/mg protein. There was a significant difference between the two groups (P less than 0.01-0.001). The activity of demethylase reflected the metabolic level of N-nitrosamine. In the control group, metabolic level of N-dimethyl-nitrosamine, N-methyl-N-butylacetonylnitrosamine and nitrosopyrrolidine was markedly higher than the copper and zinc groups. It is indicated that copper and zinc inhibit obviously the activity of demethylase, resulting in reduction of the metabolic activation of N-dimethylnitrosamine, N-methyl-N-butylacetonylnitrosamine and nitrosopyrrolidine. The role of copper and zinc in the chemical carcinogenesis is discussed.

[Alterations of oncogenes in human fetal esophageal epithelium induced by N-methylbenzylnitrosamine (NMBzA)].

Epidemiological investigation showed that N-methylbenzylnitrosamine (NMBzA) has been associated with increased incidence of esophageal cancer (EC) in Linxian county, a high incidence area. In present study, our results indicate that NMBzA can induce amplification and over-expression of EGFr gene in human fetal esophageal epithelium (HFE) treated with NMBzA for 24 hours as shown by southern blot assay and immunohistochemistry. The papillary hyperplasia was induced in HFEs that cultured with NMBzA for 1 to 3 weeks. Amplification of c-myc and int-2 gene in HFEs treated by NMBzA for 1 week and 3 weeks was found, respectively. Deletions of p53 and Rb gene were found in human fetal esophageal carcinomas induced by NMBzA. Overexpression of p53 protein in human fetal esophageal carcinomas detected by immunohistochemical methods indicates that p53 gene mutation(s) may be occured. The HFE explants treated in vitro with NMBzA for 3 weeks were inoculated subcutanously into balb/c nude mice. No tumor was found in 5 months after inoculation, suggesting that only changes of oncogene(s) are insufficient to induce full transformation. Other genetic alterations (such as functional inactivation of Rb or/and p53 tumor suppressor genes) may be necessary in the further progression of malignant lesions.