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Biomedical subjects

X Y Meng

Publications and source records attributed to X Y Meng.

At least 19 recordsLinked to original sources
PubMed2005

Characterization of a facultative endosymbiotic bacterium of the pea aphid Acyrthosiphon pisum.

The pea aphid U-type symbiont (PAUS) was investigated to characterize its microbiological properties. Fluorescence in situ hybridization (FISH) and electron microscopy revealed that PAUS was a rod-shaped bacterium found in three different locations in the body of the pea aphid Acyrthosiphon pisum: sheath cells, secondary mycetocytes, and hemolymph. Artificial transfer experiments revealed that PAUS could establish stable infection and vertical transmission when introduced into uninfected pea aphids. When 28 aphid species collected in Japan were subjected to a diagnostic PCR assay, four species of the subfamily Aphidinae (Aphis citricola, Aphis nerii, Macrosiphum avenae, and Uroleucon giganteus) and a species of the subfamily Pemphiginae (Colopha kansugei) were identified to be PAUS-positive. The sporadic incidences of PAUS infection without reflecting the aphid phylogeny can be best explained by occasional horizontal transfers of the symbiont across aphid lineages.

Animals↗
PubMed1999

Study on the direct electron transfer process of superoxide dismutase.

The electron transfer process of biological important species, superoxide dismutase (SOD), was studied using cyclic voltammetric method at different conditions. The rate of electron transfer process of SOD at conventional bare gold electrode was very low. Different methods were used to enhance the rate of this process. Gold microdisk electrode and gold minigrid electrode were used to replace the used conventional size gold electrode and the electron transfer rate was enhanced obviously. Different promoters, such as bis(4-pyridyl)disulfide, histidine and arginine, were used to promote the electron transfer process also. Promising results were observed with the help of those promoters. The rate enhancement through the participation of amino acids might be more interesting for the exploration of the real process of SOD-related reaction inside the human body.

Arginine↗
PubMed1998

Diagnosis of hepatocellular carcinoma by quantitative detection of hepatoma-specific bands of serum gamma-glutamyltransferase.

Tissues of hepatocellular carcinoma (HCC) can express hepatoma-specific gamma-glutamyltransferase (GGT) and secrete GGT into circulating blood. Serum GGT was separated into several bands (up to 11), including hepatoma-specific bands (HSBs, I', II, and II') by a vertical slab electrophoresis assay of polyacrylamide stage gradient gel. In the present study, the HSBs of serum GGT were separated, and the HSB activity was quantitatively measured in 91 patients with HCC and compared with that of 106 patients with benign liver disease, 16 patients with extrahepatic tumors, and 30 healthy control subjects. Significant differences of the HSB activity were observed between the HCC group and each study group. An HSB activity greater than 5.5 U/L seems to be diagnostic of HCC. The quantitative method has a sensitivity of 85.3%, a specificity of 97.2%, a positive predictive value of 95.1%, a negative predictive value of 91.2%, and an accuracy of 92.5% for detecting HCC. No correlation was found between HSB activity and the serum alpha-fetoprotein (AFP) level or tumor size in patients with HCC. The quantitative analysis of HSB activity of GGT is superior to detection of the AFP concentration and is useful in early diagnosis of small HCC or AFP-negative HCC.

Adult↗
PubMed1997

Mutations in a hydrophilic part of the core gene of hepatitis C virus in patients with hepatocellular carcinoma in China.

We investigated the association between hepatocellular carcinoma (HCC) and the genomic characteristics of the hepatitis C virus (HCV) isolated from residents of the inshore region of the Yangtze River, an area that has one of the highest incidence of HCC in China. We determined the genomic heterogeneity of HCV, and the sequence divergence of the HCV core gene in individuals with chronic hepatitis and HCC. HCV genotype II was predominant among these isolates, which were homologous to other Chinese and Japanese HCV isolates. The rate of nucleotide substitutions in the core gene was significantly greater for isolates from HCC patients than for those from individuals with chronic hepatitis. The nucleotide substitutions were unevenly scattered along the core gene; a cluster of missense mutations was apparent in the region encoding the second hydrophilic domain of the core protein. The rate of occurrence of missense mutations per nucleotide substitution was significantly greater in this clustering variable region (CVR) of the core gene than in the remaining core gene sequence. These observations suggest that mutations in the CVR may be involved in the pathogenesis of chronic HCV infection during hepatocellular carcinogenesis.

Base Sequence↗
PubMed1994

Perforated amebic liver abscess: clinical analysis of 110 cases.

In this study of 503 consecutive cases of amebic liver abscess documented during a 21-year period, 110 (22%) were complicated by perforation. Perforation sites included pleuropulmonary structures (79 cases, 72%) subphrenic space (15 cases, 14%); and peritoneal cavity (11 cases, 10%). The less common sites were the thoracic and abdominal wall, pericardial sac, bile duct, kidney, mediastinum, colon, and right flank. Trophozoites were recovered in 29% of cases. For the rest of the cases, diagnosis was based on the clinical manifestations and the dramatic response to a therapeutic trial of amebicides. Open surgical drainage was done in 10 of 11 patients who had peritoneal perforation; 6 of them were cured and 5 died. Of 97 patients with perforation sites other than the peritoneal cavity, 64 were treated with metronidazole in addition to needle aspiration and/or percutaneous catheter drainage, and all achieved complete remission without relapse during subsequent follow-up. Of the 36 cases treated with metronidazole alone, 22 (61%) were cured. The mortality rate in the group with perforated abscess was 17% (19/110), compared with 5% (25/503) in the whole series. The results suggested that (1) amebic liver abscess can be difficult to diagnose, especially when the pathogen is not isolated; and (2) metronidazole combined with needle aspiration and/or percutaneous catheter drainage is the treatment of choice for amebic liver abscess with perforation.

Adolescent↗
PubMed1994

Professional behaviour of medical school graduates: an analysis.

Recent graduates (1989-1990) of a traditional school of Chinese medicine were assessed by observers using a 10-item scale for professional behaviour in the non-cognitive realm. Overall, 10.7% of the graduates had low ratings on this scale. Of those who scored in the top two quartiles on this scale, 71.4% reported that 'Professional ethics' was the key determinant of their professional behaviour, whereas legal concerns were the prime motivator for only 3.6% of the top scorers. It was also found that students' scores in the medical ethics course correlated with their professional behaviour score to a statistically significant degree.

Attitude of Health Personnel↗
PubMed1994

Virological features of hepatitis C virus infection in patients with liver diseases in the inshore area of the Yangtze River.

The prevalence, genotypes, coinfection and putative core gene sequence of hepatitis C virus (HCV) were investigated in the inshore area of the Yangtze River, where hepatocellular carcinoma (HCC) is thought to be very common. Most patients with liver diseases were infected with hepatitis B virus (HBV), but the incidence of anti-HCV was very low, being 3.4% in patients with acute hepatitis, and approximately 7% in those with chronic liver diseases. The rate of coinfection with HBV and HCV in patients with HCC was 4.5%, which was similar to that in Shanghai (5.6%), but lower than that in Yangzhou (31.2%), Beijing (26.8%) and Zhejiang (28.6%). Of 124 patients with non-A, non-B (NANB) liver disease, 15 (12.1%) were positive for anti-HCV. HCV genotype analysis in 41 HCV-RNA-positive patients with liver diseases showed that genotype II was dominant (85.4%), followed by genotype III (7.3%) and II+III (7.3%). No genotype I or IV was found. The genome sequences of the HCV putative core gene from two patients with chronic hepatitis were more closely similar to those of previous isolates from Japan and China, than to that of an American isolate. These results suggest that HCV infection is not an important etiological factor for liver diseases, and that the HCV isolates in China are from the same subgroup as those in Japan.

Adult↗
PubMed1994

[Synthesis and biological activities of 2,4-diamino-5-fluoro-6-substituted benzylamino quinazolines].

The title compounds were synthesized by condensation of 5-fluoro- 2, 4, 6-triaminoquinazoline (6a) with various substituted benzaldehydes to produce the corresponding Schiff bases, followed by reduction. II and III were obtained by formylation and nitrosation of I, respectively, IV were obtained by reduction of II. Primary screening for suppressive therapeutic effects against P. berghei in mice showed that six of the twenty-two compounds produced 100% suppression when administered orally at a dose of 1 mg.kg-1. All compounds exhibited potent activity against L1210 cell in vitro. Among them I4 was more active than MTX. A number of compounds showed moderate activities against Diplococcus pneumoniae in vitro tests.

Animals↗
PubMed1992

Diagnostic value of serum gamma-glutamyl transferase isoenzyme for hepatocellular carcinoma: a 10-year study.

Serum gamma-glutamyl transferase (GGT) was separated into nine to 11 isoenzyme bands (designated as GGT I-XI) by vertical slab electrophoresis on polyacrylamide gradient gel. The diagnostic value of GGT isoenzyme II (GGT II) for hepatocellular carcinoma (HCC) was studied, and the results were as follows: 1) GGT II was positive in 90% of 90 cases of HCC, and negative in most patients with acute and chronic viral hepatitis, extrahepatic tumors, in pregnant women, and in healthy controls; 2) the positive rate of GGT II assay was higher than that of alkaline phosphatase isoenzyme I (ALP I), alpha-fetoprotein (AFP), and alpha 1-antitrypsin (AAT) in 101 cases of HCC. In cases in which the AFP was greater than 50 ng/ml or less than 50 ng/ml, the positive rates of GGT II were 70.8% and 75-100%, respectively; 3) of 14 cases of small-size HCC, the positive rate of GGT II was 78.6%, which was higher than that of AFP (50%), AAT (28.6%), and ALP I (0%); 4) of 62 cases that were false-positive for GGT II assay, 24.2% developed into HCC during a follow-up of 2.1-20 months. In subjects with persistent and recurrent positivity of GGT II, 86.7% and 22.2%, respectively, developed HCC. No patient with temporal positivity of GGT II developed HCC. The results show that GGT II can be applied as an additional marker for HCC, and is valuable not only for the diagnosis of clinical HCC, but for the detection of small or subclinical HCC. Periodic follow-up with assay of GGT II in patients at high risk for HCC may predict the development of hepatoma.

Biomarkers, Tumor↗
PubMed1991

[Synthesis and antibacterial as well as antineoplastic activities of 2,4-diamino-5-methyl-6-(N-methyl-substituted benzyl) aminoquinazolines].

This paper reports four methods for the synthesis of 2,4-diamino-5-methyl-6-(N-methyl-substituted benzyl) aminoquinazolines. Six compounds were synthesized and all these compounds showed good anticancer and antibacterial activities. Among them, I5 showed the strongest inhibition against L1210 Leukemia cell and further research has to be done.

Animals↗
PubMed1990

Reappraisal of diagnostic significance of a hepatoma-specific band of serum gamma-glutamyl transferase.

The hepatoma-specific band of serum gamma-glutamyl transferase II (GGT II) and other three markers were evaluated in 77 patients with primary hepatocellular carcinoma (PHC). The positive rate of GGT II (87%) was much higher than that of the increased alpha-fetoprotein (AFP greater than or equal to 400 ng/ml, 54.5%), the increased alpha-1-antitrypsin (AAT greater than or equal to 400 mg/dl, 64.9%) and alkaline phosphatase isoenzyme I (ALP I, 13.0%). In patients with AFP less than 400 ng/ml, the positive rate of GGT II was 95.2%, higher than that of ALP I (22.8%) and AAT (60.0%). The positive rate of GGT II was positively correlated to the volume of PHC (r = 0.324, P less than 0.05), but even in patients with small PHC (less than or equal to 65 cm3), the positive rate of GGT II (78.6%) was higher than that of AFP (50.0%) and AAT (28.6%). The ALP I positivity was only seen in patients with larger PHC. Follow-up study showed that GGT II, like AFP, might occur before liver tumor could be detected by B-mode ultrasonography and computerized tomography. Therefore, GGT II is a valuable marker of PHC, especially in patients whose AFP was negative or slightly increased; GGT II may be useful for relatively early diagnosis of PHC.

Biomarkers, Tumor↗
PubMed1989

Serum alpha-1-antitrypsin and alpha-1-antichymotrypsin in the diagnosis of primary hepatocellular carcinoma.

Both alpha-1-antitrypsin (AAT) and alpha-1-antichymotrypsin (AAC) in serum were investigated in various liver diseases. Serum levels of AAT and AAC in normal controls were 293.3 +/- 37.9mg/dl and 119.6 +/- 18.9U/ml, respectively. Both AAT and AAC were significantly higher in 75 patients with primary hepatocellular carcinoma (PHC) than in patients with acute viral hepatitis, chronic hepatitis, liver cirrhosis as well as normal controls. In a cut-off value of more than 400 mg/dl AAT showed a sensitivity rate (SS) of 74.7%, specificity (SP) of 97.3%, positive predictive value (PV+) of 86.2%, negative predictive value (PV-) of 95.5% and a total accuracy of 93.3% for diagnosing PHC. In a cut-off value of more than 157 U/ml, the corresponding figures for AAC were 68.0%, 96.7%, 86.4%, 90.6% and 90.0%. If the increased levels in one or both tests are positive, the combined positive rate is 80.0% in PHC. In 11 PHC cases with serum alpha-fetoprotein (AFP) less than 50 ng/ml, the positive rate of AAT and AAC were 72.7% and 81.8%, respectively, compared to corresponding figures of 71.7%, and 65.2% in 46 cases of PHC with more than 50 ng/ml of AFP. It shows that combined assay of both serum AAT and AAC has a complemental value in the diagnosis of PHC, especially in patients without increased AFP.

Biomarkers, Tumor↗
PubMed1989

[Synthesis and antimalarial and antineoplastic activities of some derivatives of 2,4-diamino-5-methyl-6-substituted benzylaminoquinazolines].

This paper reports the synthesis and the antimalarial and anticancer activities of some derivatives of 2,4-diamino-5-methyl-6-substituted benzylaminoquinazolines. These compounds were synthesized by condensation of 5-methyl-2,4,6-triaminoquinazoline with substituted benzyaldehyde to produce Schiff base, followed by reduction, formylation or nitrosation. The suppressive therapeutic effects against Plasmodium berghei in mice showed that the suppressive rate of three compounds (IV 2,5,6)was 100 per cent at the dosage 5 mg/kg. The anticancer activity in vitro showed that II7 and IV3 had the strongest inhibition and their IC50 against L1210 Leukemia cell were 3.910 X 10(-3) micrograms/ml and 6.172 X 10(-3) micrograms/ml.

Aminoquinolines↗