Biomedical subjects
Publications and source records attributed to G Y Li.
Three compounds were isolated from the stems and leaves of Rabdosa nervosa. On the basis of spectral analysis their structures were elucidated as lasiokaurin, ponicidin and oridonin respectively. These compounds were obtained from R. nervosa for the first time.
BACKGROUND: Epidemiologic evidence indicates that diets high in fruits and vegetables are associated with a reduced risk of several cancers, including cancers of the esophagus and stomach. Vitamins and minerals in these foods may contribute to the reduced cancer risk. The people of Linxian County, China, have one of the world's highest rates of esophageal/gastric cardia cancer and a persistently low intake of several micronutrients. PURPOSE: We sought to determine if dietary supplementation with specific vitamins and minerals can lower mortality from or incidence of cancer as well as mortality from other diseases in Linxian. METHODS: Individuals of ages 40-69 were recruited in 1985 from four Linxian communes. Mortality and cancer incidence during March 1986-May 1991 were ascertained for 29,584 adults who received daily vitamin and mineral supplementation throughout this period. The subjects were randomly assigned to intervention groups according to a one-half replicate of a 2(4) factorial experimental design. This design enabled testing for the effects of four combinations of nutrients: (A) retinol and zinc; (B) riboflavin and niacin; (C) vitamin C and molybdenum; and (D) beta carotene, vitamin E, and selenium. Doses ranged from one to two times U.S. Recommended Daily Allowances. RESULTS: A total of 2127 deaths occurred among trial participants during the intervention period. Cancer was the leading cause of death, with 32% of all deaths due to esophageal or stomach cancer, followed by cerebrovascular disease (25%). Significantly (P = .03) lower total mortality (relative risk [RR] = 0.91; 95% confidence interval [CI] = 0.84-0.99) occurred among those receiving supplementation with beta carotene, vitamin E, and selenium. The reduction was mainly due to lower cancer rates (RR = 0.87; 95% CI = 0.75-1.00), especially stomach cancer (RR = 0.79; 95% CI = 0.64-0.99), with the reduced risk beginning to arise about 1-2 years after the start of supplementation with these vitamins and minerals. No significant effects on mortality rates from all causes were found for supplementation with retinol and zinc, riboflavin and niacin, or vitamin C and molybdenum. Patterns of cancer incidence, on the basis of 1298 cases, generally resembled those for cancer mortality. CONCLUSIONS: The findings indicate that vitamin and mineral supplementation of the diet of Linxian adults, particularly with the combination of beta carotene, vitamin E, and selenium, may effect a reduction in cancer risk in this population. IMPLICATIONS: The results on their own are not definitive, but the promising findings should stimulate further research to clarify the potential benefits of micronutrient supplements.
Linxian, China, has one of the highest esophageal-cancer mortality rates in the world. In 1983, esophageal balloon-cytology screening was performed to identify subjects eligible for 2 nutrition-intervention trials in Linxian; 12,877 subjects had cytology slides which were satisfactory for diagnosis. Of the 12,649 subjects with squamous-cell diagnoses, 31% were normal by Chinese cytologic criteria; 38% showed hyperplasia; 21% showed dysplasia 1; 6% showed dysplasia 2; 2% showed near-cancer; and 2% showed cancer. Of the 1,471 subjects with columnar-cell diagnoses, 31% were normal; 44% showed hyperplasia; 16% showed dysplasia 1; 4% showed dysplasia 2; 2% showed near-cancer; and 3% showed cancer. Squamous dysplasia and cancer were more common among females than males, while columnar dysplasia and cancer showed male predominance. The prevalence of dysplasia and cancer of both cell types increased with age. The prevalence of squamous dysplasia was significantly higher than in earlier balloon-cytology screenings in Linxian, probably reflecting changes in cytologic classification.
Six neo-clerodane diterpenoids were isolated from the acetone extract of Teucrium quadrifarium Buch-Ham (I, II, IV, V, VI and VII). Five of them (I, II, IV, V and VII) were identified as known compounds, teucvidin, 12-epi-teucvidin, teuflin, 19-acetyl-teuspinin and teucvidin, respectively. Compound VI was found to be a new neo-clerodane diterpene, named teuquadrin B. Its structure has been determined from the physical and spectral data.
Six compounds were isolated from Rosa laevigata. Five of them were obtained from the ethanolic extract and identified as 2 alpha, 3 beta, 19 alpha, 23-tetrahydroxyurs-12-en-28-oic acid, 2 alpha, 3 alpha, 19 alpha, 23-tetrahydroxyurs-12-en-28-oic acid, euscaphic acid, beta-sitosterol and daucosterol. The other one was obtained from the acetate of emulsive layer of the petroleum ether and elucidared as 2 alpha, 3 beta-dihydrolup-28-methyl ester diacetate.
The mitochondrial leucyl-tRNA synthetase (mLRS) of Saccharomyces cerevisiae is involved in both mitochondrial protein synthesis and pre-mRNA splicing. We have created mutations in the regions HIGH, GWD and KMSKS, which are involved in ATP-, amino acid- and tRNA-binding respectively, and which have been conserved in the evolution of group I tRNA synthetases. The mutants GRD and NMSKS have no discernible phenotype. The mutants AWD and ARD act as null alleles and lead to the production of 100% cytoplasmic petites. The mutants HIGN, NIGH and KMSNS are unable to grow on glycerol even in the presence of an intronless mitochondrial genome and accumulate petites to a greater extent than the wild-type but less than 40%. Experiments with an imported bI4 maturase indicate that the lesion in these mutations primarily affects the synthetase and not the splicing functions.
Serum bile acids have been shown to serve as useful indicators of liver disease. We have confirmed these findings and added an analysis of interleukin-1 beta (IL-1 beta) profiles to further differentiate viral hepatitis from toxic liver damage associated with exposure to vinyl chloride (VC) or trinitrotoluene (TNT). The frequency of elevated cholylglycine (CG) was 100%, 75%, and 37.5% in viral hepatitis, VC- and TNT-linked liver injury patients, respectively. The mean levels, expressed in micrograms/dL, were 578, 507, 142, and 65 in hepatitis B, hepatitis non-A non-B, VC and TNT liver injury patients, respectively. Thus, the CG test could detect viral hepatitis and, VC liver injury, and (less frequently) liver injury associated with exposure to TNT. The mean level of IL-1 beta in patients with hepatitis type B was 424 pg/mL and hepatitis non A non B was 384 pg/mL compared with a mean of 33-40 pg/mL in those with VC or TNT-linked liver disease. The IL-1 beta detection test proved further to be an important distinguishing parameter as it was 100% positive in patients with viral hepatitis but only 12.5% to 25% positive in patients with VC/TNT-induced liver damage.
For the incidence of non-volatile nitrosamines in the staple foods and vegetables, corn, millet, turnip and turnip chips collected from Linxian County Henan Province, a high incidence area of esophageal cancer, were collected, analyzed and compared with the foods from Huairou County Beijing, a low risk area. Nitrososarcosine (NSAR), nitrosoproline (NPRO) and two unknown non-volatile compounds were found in the food samples from Linxian, and the levels of NSAR in corn ranged 0.7-1.1 ppb and in turnip chips ranged 20.5-962.5 ppb. NSAR level detected in corn samples from Huairou County was not significantly different from that of Linxian. The possibility that the high content of nitrosamines in turnip chips is due to microbial infections is discussed.
Two epithelial tumor cell lines were established from biopsy specimens of 2 nasopharyngeal carcinomas (NPC) and designated HNE-1 and HONE-1. Uncloned HNE-1 cells were found to be Epstein-Barr virus (EBV) DNA-positive when examined by Southern blot analysis up to passage 35, after which the EBV genome could no longer be detected. A similar loss of EBV DNA took place in uncloned HONE-1 cells. However, HONE-1 clone 40 cells are still EBV DNA-positive up to passage 42 thus far and cell cultures contain 85-90% EBV nuclear antigen (EBNA)-positive cells. The HNE-1 cell line has been passaged more than 100 times and the uncloned HONE-1 cells more than 90 times. The tumorigenicity of the HNE-1 and HONE-1 cells was demonstrated by tumor induction in nude mice. Karyotypic analysis of the HNE-1 cells demonstrated an aneuploidy with a modal chromosomal number of 74 at passages 5 and 101 at passage 20; 18 marker chromosomes were identified. We have continued to map the EBV genome latently associated with the HNE-1 and HONE-1 cells using the Bam HI, EcoRI or Hind III restriction enzymes. Using EcoRI fragments A-K as probes, we found that HNE-1 EBV DNA is different from B95-8 and HR-1 EBV DNA in the EcoRI-C region. The Bam HI map for HONE-1 EBV DNA is very similar to the B95-8 map; it contains the Bam HI-Y fragment but without Bam HI B' and WI'. Differences were observed between HONE-1 EBV DNA and B95-8 DNA using the Hind III restriction enzyme. There was no evidence of spontaneous expression of the latent EBV genome in HNE-1 cells, and attempts to induce replication of the latent EBV genome and rescue infectious virus have failed, suggesting a tightly restricted virus genome.
A randomized triple-blind and placebo-controlled clinical trial on the effect of lidocaine and Anodyne-lubricant jelly (ALJ) containing dicaine on cervical dilatation is reported. Three-hundred-seventy-two consecutive cases were randomly allocated to 4 groups. The four groups were given: ALJ and placebo (placebo 1); and lidocaine and placebo (placebo 2). ALJ and placebo 1 treatment was by topical application, and lidocaine and placebo 2 by injection. In parous women, a significant difference was found for satisfactory dilatation (SD) rate (p less than 0.01) among four groups. It was unexpected that there were no significant differences between drug and placebo groups, neither between ALJ treatment group and placebo 1 group (p greater than 0.5), nor between lidocaine and placebo 2 (p greater than 0.75). However, the combined SD rate was 60.9% for the topical groups compared with 39.0% for the injection groups (p less than 0.005). The findings suggested that the effect of ALJ on cervical dilatation was not mainly due to dicaine, but associated with the lubricant and the topical treatment.
The first successful excision of a left atrial myxoma in China was performed in 1962. Till October 1988, 656 surgical cases of cardiac tumors have been reported in the Chinese literature. The diagnosis of all excised tumors was confirmed by pathologic studies. The age of patients ranged from 46 days to 72 years. Among these 656 cases, 647 tumors were benign (97%) and 9 tumors were malignant (3%). 633 myxomas (97.8%) represented the vast majority of the benign cardiac tumors. In 26 cases, myxomas were found multilocalized. Before 1975, echocardiography could not be performed universally in our country, and diagnosis often failed. At present, echocardiography is the most used and the most reliable examination method for cardiac tumors in China. The majority of the patients presented clinical symptoms of congestive heart failure with palpitation, dyspnoe, syncope, and hemoptysis. In 99% the main abnormality was an atypical and frequently variable heart murmur. Arterial embolization occurred in 15%. In all patients the myxomas was removed as a whole with its attachment to the interatrial septum or the atrial wall to prevent recurrence. Examination of all heart chambers should be performed to exclude multilocalized tumors. The operative mortality ranged between 5.8 to 13%. The recurrence rate of myxomas in China was reported to amount to 3%.
Eighty-two patients with giant-cell tumor of the bone were operated with 4 different methods depending on the site of tumor, extent of local invasion and degree of malignancy. Curettage plus filling operation was performed for Grade I tumors and localized lesions. Resection of the tumor segment and replacement of the joint with allograft or artificial joint were done for Grade II tumors involving the joint but with clear borders. The indications of amputation were Grade III tumors, frequent recurrence and malignant change. Local curettage plus radiotherapy was undertaken in tumors that could hardly be completely curetted, such as tumors in the sacrum and spine. The results showed that the first method gave a high recurrence rate; the second method was the best; the third was worse due to conservativeness of amputation; the fourth method had the poorest prognosis owing to incomplete removal of the tumor.
A case-control study involving interviews with 1,244 patients (758 males and 486 females) with cancer of the esophagus or gastric cardia and 1,314 population-based controls (789 males, 525 females) was carried out in Linxian, a rural county in North Central China with one of the world's highest mortality rates for these tumors. Cancer risks tended to rise with increasing intake of wheat and corn, but no association was found with adult intake of pickled vegetables, the leading a priori suspect, and risks were not elevated among those consuming low quantities of fresh vegetables or fruits. Few differences in preparation or storage of food or water were detected, although cancer patients reported less fluid intake than controls. Few persons reported drinking alcoholic beverages. Smoking was reported by 61% of the male cases and was a mild risk factor, related more to cancer of the cardia than of the esophagus. The risk was increased by 70% among those whose parents had esophageal or stomach cancer, but only slightly among those whose spouses had such cancers, suggesting that exposure early in life and/or genetic effects may be involved.
Sister chromatid exchange (SCE) is a genetic indicator of DNA damage in mammalian cells and may afford a sensitive monitor to follow genomic instability of some individuals with fragile chromosomal diseases or malignancies. In studies on the effect of dinitrosopiperazine (DNP), aflatoxin B1 (AFB1), methyl-nitro-nitroso-guanidine (MNNG) and Epstein-Barr virus (EBV) infection on SCE in lymphocytes from nasopharyngeal carcinoma (NPC) patients, we found that: (1) the spontaneous SCEs in peripheral blood lymphocytes (PBLs) from 75 NPC patients were significantly higher than those of PBLs from 44 normal adults, 24 cord blood (CBL) specimens, and PBLs from 20 patients with chronic inflammation of the nasopharynx; (2) PBLs from NPC patients who were positive for EBV virus capsid antigen (VCA) IgA antibody had a higher SCE frequency as compared with PBLs from VCA IgA-negative NPC patients; (3) the chemical carcinogens used induced significantly higher SCEs in lymphocytes from NPC patients than in PBLs from normal adults and CBLs; (4) the mean SCEs of EBV growth-transformed CBLs increased from 5.17 to 14.12 after infection and was similar to the level of SCEs found in PBLs from the VCA IgA-positive NPC patients. The data suggest that lymphocytes of NPC patients might be more fragile than the lymphocytes of the control groups studied.
Two epithelial tumor cell lines were established from biopsy specimens of nasopharyngeal carcinomas (NPC). The specimens were taken from poorly differentiated squamous cell carcinomas of the nasopharynx. The tissues were prepared for cell culture and eventually two continuous epithelial cell lines were obtained and designated HONE-1 and HNE-1. Light and electron microscopic examination of these two cell lines demonstrated cells with an epithelial morphology including the presence of desmosomes. The HNE-1 cell line has been passaged more than 100 times and the HONE-1 cell line has been passaged more than 90 times. It was found that early-passage uncloned HNE-1 cells (passage 23) could be superinfected with the B95-8 and NPC-EBV isolates as demonstrated by the induction of Epstein-Barr virus (EBV)-specific early antigen(s) in a small percentage of the cells; HONE-1 cells could also be superinfected with EBV. Southern blot analysis detected EBV DNA in samples from uncloned HNE-1 cells at passages 12, 17, 21, 27, and 35. However, by passage 45, EBV DNA could no longer be detected in HNE-1 cells by Southern blot analysis. The EBV genome was detected in parental HONE-1 cells at subculture 9 and in clone 40 cells up to passage 40 thus far. When HNE-1 cells were examined for the expression of the EBV-encoded nuclear antigen (EBNA) at passage 12, only about 10% of the cells were found to be positive. The percentage of EBNA-positive HNE-1 cells decreased as the cells were passaged. A similar loss of EBNA was observed in uncloned HONE-1 cells, but not in HONE-1 clone 40 cells. In clone 40, which has been passaged 40 times thus far, 85-90% of the cells are still EBNA-positive. The data suggest that EBV genome-positive HNE-1 and HONE-1 cells were lost as the cells were cultivated in vitro and that cloning the cells at an early passage level may be critical in maintaining EBV genome-positive epithelial NPC cells. These EBV genome-positive epithelial NPC cell lines will be useful for studying the association of EBV and NPC.
N-2-methylpropyl-N-1'-methylacetonylnitrosamine (NMAMPA) is a new N-nitroso compound found in natural moldy millet and wheat flour from Linxian county, Henan Province. The volatile nitrosamine is mutagenic in several short-term biological assays, and so we proceeded to synthesize larger amounts for the study of carcinogenesis. The main steps were as follows: 1) preparation of 3-bromobutanone (I) by bromination of butanone, 2) alkylation of 3-bromobutanone (I) with isobutylamine to give the secondary amine (II), and 3) nitrosaton of secondary amine (II) with sodium nitrite to yield NMAMPA (III). NMAMPA is a pale yellow liquid which is slightly soluble in water and freely soluble in ether, chloroform and dichloromethane. At room temperature, NMAMPA slowly turns brown, and decomposition takes place after prolonged exposure to UV light. A dilute solution of NMAMPA may be degraded in a freezer at 4 degrees to 6 degrees C.
Operation of interbody fusion done on 18 cases of lumbar spondylolysis with 1 degree spondylolisthesis resulted in complete relief of symptoms in all the patients. Through a follow-up period of 2 to 10 years, these 18 patients have been living a normal life without restriction of activity, including sexual intercourse. We would say that interbody fusion for spondylolysis is anatomically sound and biomechanically reasonable.
Sixteen 2,4-diamino-6-(N-methyl-substituted benzylamino) quinazolines (I) were synthesized by two different methods. 2-Nitro-5-chloro-benzonitrile was treated with the appropriate N-methyl-substituted benzylamines and I was formed after reduction and cyclization. Another method was reductive methylation, i.e., 2,4-diamino-6-substituted benzylaminoquinazolines reacted with formaldehyde and sodium cyanoborohydride at pH 6.3. Suppressive therapeutic tests in mice infected with Plasmodium berghei showed that four (I6,7,10,16) out of these compounds suppressed all the parasites when administered orally at the dose of 5 mg/kg and produced more than 99% suppression at 2.5 mg/kg. Eight compounds (I1,2,4,5,8-10,15) were found to have antitumor effects against Leukemia cells in culture comparable with or superior to those of the positive control methotrexate.