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Biomedical subjects

Z Meng

Publications and source records attributed to Z Meng.

At least 73 records · Page 4Linked to original sources
PubMed1995

Sister-chromatid exchanges in lymphocytes of workers at a phosphate fertilizer factory.

The frequencies of sister-chromatid exchange (SCE) in peripheral blood lymphocytes of 40 workers at a phosphate fertilizer factory in North China were studied. HF and SiF4 are main air pollutants in the factory, there is also some dust containing fluoride, phosphate fog, NH3 and SO2. It was shown that the chemicals caused an increase in SCE, and also induced cell mitotic delays. The mean SCEs/cell of the workers and the non-exposed controls were 7.47 +/- 0.31 and 4.94 +/- 0.14 (p < 0.01) respectively. SCEs/cell in 75% of 40 workers were higher than 6 while 40 controls all had values lower than 6. SCE frequencies of the workers increased with length of the chemical exposure period up to 10 years. Smoking enhanced the SCE frequencies induced by the chemicals.

Air Pollutants, Occupational↗
PubMed1995

[Preparation and identification of monoclonal antibody against sterigmatocystin].

Compound antigen, bovine serum albumin-sterigmatocystin (BSA-ST) or hemocyanin sterigmatocystin (H-ST) was prepared by converting ST to its hemiacetal group in ST and taking ST conjugated to BSA or H. Balb/c mice were immunized with BSA-ST, and then their spleen cells were isolated and fused with SP2/0 murine myeloma cells. A hybridoma cell strain that could stably secrete monoclonal antibody against ST (McAb-ST) was selected, and both of their ascites and serum were rich in McAb-ST induced by cells of this strain. McAb-ST was identified as Ig-Gi with a molecular weight of 168,000 kd (53,000 for heavy chain and 31,000 for light one), and with an affinity constant of H-ST reaction of 1.29 x 10(9) mol/L measured by indirect competitive enzyme-linked immunosorbent assay (IC-ELISA). Relative cross reaction of McAb-ST with ST analogues was less than 2%. The minimal 0.5 pg/25 microliters of ST can be detected with IC-ELISA using McAb-ST and ST simultaneously, with a linear range of 0.1-10 ng/ml.

Animals↗
PubMed1995

[An eight-year prospective study on 163 cases of hepatitis C].

To explore the characteristics of hepatitis C in China, one hundred and sixty three cases of hepatitis C were followed for 8 years. The rates of abnormal alanine aminotransferase (ALT) were 100%, 73%, 57%, 37% and 28% in less than one, 1, 2, 5 and 8 years after the onset respectively. Abnormality of ALT might be persistent or fluctuating, and the latter type accounted for about 1/3 to 1/2 of the cases. The positive rates of anti-hepatitis C virus (HCV) were 56%, 93%, 94%, 96%, 97%, 93% and 83% in less than two, 2-6, 7-12 months and 1, 2, 5 and 8 years after the onset respectively. Negative conversion of anti-HCV was found only in a few patients whose ALT had returned to normal level and the rates of negative conversion for them were 10%, 8%, 16%, and 22% in 1, 2, 5 and 8 years after the onset. Positive rate of HCV-RNA, detected with nested PCR 8 years after the onset was 84% for patients who still showed positive anti-HCV and there was no significant difference between patients with abnormal (80%) and normal ALT (85%) levels. Genotype II accounted for 93% of the cases. No patient developed hepatocellular carcinoma or decompensated cirrhosis after a follow-up of eight years.

Adolescent↗
PubMed1995

[Production and characterization of sterigmatocystin].

Two strains of Aspergillus versicolor producing ST at 550.8 mg.kg-1 substrate and 1160.8 mg.kg-1 substrate were selected to inoculate 4 kg solid ST-producing media. After 35 days stationary incubation at 28 degrees C in the dark, 2271.6 mg of pale-yellow needle-shaped crystals were isolated and purified from the culture with a procedure applying column chromatography and recrystallization method. The crystal was proved to be sterigmatocystin by spectroanalysis and some physico-chemical analysis. The purity of the final material obtained were more that 99.9% as shown by HPLC and TLC detection. With this procedure, ST was obtained at about one tenth of its commercial cost.

Aspergillus↗
PubMed1995

[The functional connection among the "zusanli"-spinal dorsal horn neurons-trigeminal sensory nucleus of rats].

Electrical stimulation of Zusanli (ST36) point and Trigeminal Sensory Nucleus (TSN) as well as microelectrode recording from the laminae II - VI of the lumbar spinal dorsal horn have been used on the pentobarbital anesthetized rats, finding and identifying 142 spinal neurons responding to the stimulation of both ST36 and TSN. Among them, 29 responded antidromically to TSN; the others, responded orthodromically to TSN; These neurons distributed in the L2-S1 segments, the most in the L3-L6 segments, and in the laminae III-V, occasionally in the laminae II and VI in the spinal dorsal horn, the LTM and WDR neurons were 50% respectively of them. The results indicate that (i) single spinal dorsal horn neurons receives ST36 afferent input and then conveys it to the TSN; (ii) some spinal dorsal horn neurons receive, in turn, innervation from TSN; (iii) The convergence and integration between ST36 and TSN inputs might occur in the spinal dorsal horn neurons.

Acupuncture Points↗
PubMed1994

Effects of inorganic arsenicals on DNA synthesis in unsensitized human blood lymphocytes in vitro.

Effects of inorganic arsenicals on DNA synthesis in unsensitized human blood lymphocytes were biphasic: The chemicals at very low concentrations enhanced DNA synthesis, whereas higher concentrations inhibited DNA synthesis. The concentrations of arsenicals at which the maximum stimulating effect was found were 1 x 10(-5) M, 1 x 10(-6) or 2 x 10(-6) M, and 0.8 x 10(-6) or 1 x 10(-6) M for sodium arsenite exposure of 1 h, 3 d, and 6 d, respectively; for sodium arsenate, 1 x 10(-5) M, 1 x 10(-5) M, and 2 x 10(-6) or 5 x 10(-6) M, respectively. Arsenicals must be present for the entire 6-d culture period to produce maximum stimulation of DNA synthesis in human lymphocytes. The longer exposure of the lymphocytes to arsenicals, the lower the concentrations of arsenicals at which the maximum stimulating effect on DNA synthesis was found. Stimulating effect of trivalent arsenic (sodium arsenite) on DNA synthesis was stronger than pentavalent arsenic (sodium arsenate), and the stronger the effect of trivalent arsenic than pentavalent, the longer exposure of the cells to the chemicals. Both sodium arsenite and sodium arsenate stimulated DNA synthesis in human lymphocytes to a lower degree than phytohemagglutinin (PHA).

Arsenates↗
PubMed1994

[Chromosomal aberrations, sister chromatid exchanges and micronuclei induced in human lymphocytes by sodium bisulfite (sulfur dioxide)].

The frequencies of chromosomal aberrations (CA), sister chromatid exchanges (SCE) and micronuclei (MN) in human blood lymphocytes exposed to sodium bisulfite (sulfur dioxide) at varies concentrations ranging from 5 x 10(-5) to 2 x 10(-3) mol/L in vitro were studied. It was shown that sodium bisulfite (NaHSO3 and Na2SO3, 1:3 mol/L) caused an increase in SCE and MN of human blood lymphocytes in a dose-dependent manner, and also induced mitotic delays and decreased mitotic index of the lymphocytes. For CA, our results indicated that sodium bisulfite induced an increase of chromatid-type aberrations of the lymphocytes from three of four donors in a dose-dependent manner. The chemical at low concentrations induced chromatid-type aberrations but not chromosome-type aberrations; at high concentrations induced-both chromatid and chromosome-type aberrations of lymphocytes. No cytogenetic effects of sodium bisulfite on the human blood lymphocytes were observed in these assays. The results have confirmed that sulfur dioxide is a clastogenic and genotoxic agent.

Adult↗
PubMed1993

Effects of arsenic on DNA synthesis in human lymphocytes.

Effects of arsenic on DNA synthesis in human lymphocytes were biphasic: Either trivalent (arsenic trioxide and sodium arsenite) or pentavalent (sodium arsenate) arsenic compounds at very low concentrations enhanced DNA synthesis in human lymphocytes stimulated by phytohemagglutinin (PHA), whereas higher concentrations inhibited DNA synthesis. There were differences among individual susceptibilities to arsenic-induced DNA synthesis. Either stimulating or inhibiting effects of trivalent arsenic on DNA synthesis in PHA-stimulated lymphocytes were always stronger than those of pentavalent arsenic. Both trivalent and pentavalent arsenic could be rapidly taken up into the human lymphocytes and immediately stimulate or inhibit DNA synthesis. A possible dual effect of arsenic at very low concentrations as both comutagen and inhibitor of mutagenesis is discussed.

Arsenic↗
PubMed1993

Effects of arsenic on DNA synthesis in human lymphocytes stimulated by phytohemagglutinin.

Effects of arsenic on DNA synthesis in human lymphocytes were biphasic: either trivalent (arsenic trioxide and sodium arsenite) or pentavalent (sodium arsenate) arsenic compounds at very low concentrations enhanced DNA synthesis in human lymphocytes stimulated by phytohemagglutinin (PHA), whereas higher concentrations inhibited DNA synthesis. There were differences among individual susceptibilities to arsenic-induced DNA synthesis. Either stimulating or inhibiting effects of trivalent arsenic on DNA synthesis in PHA-stimulated lymphocytes were always stronger than those of pentavalent arsenic. It was also shown that both trivalent and pentavalent arsenic could be rapidly taken up into the human lymphocytes, and immediately stimulated or inhibited DNA synthesis. A possible dual effect of arsenic at very low concentrations as both comutagen and inhibitor of mutagenesis is discussed.

Adult↗
PubMed1993

Evaluating the efficacy of a new flossing aid.

The purpose of this clinical trial was to compare the efficacy of a new flossing aid (Flosser) with finger flossing on preventing plaque and gingival inflammation. 35 adults who did not use dental floss routinely were assigned randomly to one of 2 treatment groups (Flosser or finger flossing) in a 2-period, single-blind crossover study. After prophylaxis, subjects were instructed to use the flossing aid or finger floss 1 x per day and to continue brushing for 30 days. Gingival inflammation (GI & BPI) and plaque (PI) were assessed prior to the prophylaxis and at 30 days. After a 30 day "washout" period, subjects were again reassessed for gingival inflammation and plaque, given a prophylaxis, assigned the opposite treatment (2nd treatment period) that they received the first treatment period, and assessed (GI, BPI & PI) after 30 days. Comparing the mean difference of the 30-day buccal interproximal scores between the treatment groups (flossing aid scores minus finger flossing scores) showed that the mean differences with 95% CI were: -0.013 +/- 0.067 [GI], -0.017 +/- 0.044 [BP] and 0.019 +/- 0.014 [PI]. No statistically significant differences from zero (0.05 alpha) were observed using the t-test. There was a high level of compliance (90%) with the prescribed regiment, and subjects preferred (56%) the flossing aid slightly over finger flossing. Even though there were no statistically or clinically significant differences in gingivitis and plaque scores between the 2 flossing groups, the positive inclination for the flossing aid makes it a desirable addition to the armamentarium of preventive dentistry.

Adult↗
PubMed1993

The functional linkage among the "ZSL"-spinal dorsal horn-SN.

Electrical stimulation of the Zusanli point (ZSL) and solitary tract nucleus (SN) as well as microelectrode recording from the laminae III-V of the lumbar spinal dorsal horn have been used on the pentobarbital anesthetized rats, finding and identifying 57 spinal neurons responding to the stimulations of both ZSL and SN. Among them, 34 responded antidromically to SN; the others responded orthodromically to SN. Among them, the low-threshold mechano-receptive (LTM) neurons and wide-dynamic-range (WDR) neurons were 50 percent respectively. The results indicate that (i) a single spinal dorsal horn neuron receives somatic afferent input and then conveys it to the visceral sensory nucleus-SN; (ii) some spinal dorsal horn neurons receive, in turn, innervation from the SN; (iii) the convergence and integration between somatic and visceral sensory inputs might occur in the spinal dorsal horn neurons and/or SN.

Acupuncture Points↗
PubMed1992

Cytogenetic damage induced in human lymphocytes by sodium bisulfite.

The frequencies of chromosomal aberrations (CA), sister-chromatid exchanges (SCE), and micronuclei (MN) in human blood lymphocytes exposed to sodium bisulfite (sulfur dioxide) at various concentrations ranging from 5 x 10(-5) M to 2 x 10(-3) M in vitro were studied. It was shown that sodium bisulfite (NaHSO3 and Na2SO3, 1:3 M/M) caused an increase in SCE and MN in human blood lymphocytes in a dose-dependent manner, and also induced mitotic delays and decreased mitotic index. For CA, our results indicated that sodium bisulfite induced an increase of chromatid-type aberrations in lymphocytes from three of four donors in a dose-dependent manner. The chemical at low concentrations induced chromatid-type aberrations, but not chromosome-type aberrations; high concentrations induced both chromatid- and chromosome-type aberrations. No cytogenetic damage in human lymphocytes was induced by sodium sulfate. The results have confirmed that sulfur dioxide is a clastogenic and genotoxic agent.

Cell Division↗
PubMed1991

The projection linkage between the spinal dorsal horn neurons and both the solitary tract and dorsal column nuclei.

Electrical stimulation of the solitary tract nucleus (SN) and dorsal column nuclei (DCN) as well as microelectrode recording from the lumbal spinal dorsal horn have been used to find and identify the axonal projection of and the afferent innervation on the spinal neurons of pentobarbital-anesthetized rats. A total of 92 neurons was recorded and identified mainly in laminae III-V of the lumbar spinal dorsal horn. Of them, 38 neurons were activated antidromically from stimulation of both the SN and DCN. The other 54 neurons responded synaptically to both the SN and DCN stimulations. The initial antidromic responses of 8 neurons in the first group were followed by one or more responses synaptically driven from the SN and/or DCN stimulation. Conduction velocities were in the range of A delta fibers, but faster in the antidromic responses and slower in the synaptic responses. These results indicate that (i) some spinal neurons issue branched axons of larger-sized A delta fibers and double project to both the SN and DCN; (ii) some of these double projection neurons receive in turn smaller A delta fiber innervation from the SN and/or DCN; and (iii) some other neurons in the spinal cord are dually innervated by smaller A delta fibers originating from both nuclei.

Animals↗
PubMed1990

The effects of tartar-control toothpaste on the oral soft tissues.

Ninety-two dental and dental hygiene students completed a double-blind, controlled clinical trial. The purpose of the trial was to evaluate the effects of toothpastes, in varying concentrations of flavor and tartar-control agents. Four formulations of toothpastes were assessed: (A) control-low flavor with no tartar control; (B) medium flavoring with medium tartar control; (C) high flavoring with medium tartar control; and (D) medium flavoring with no tartar control. Soft tissue reactions were assessed objectively and independently by three examiners. Subjective perceptions about each toothpaste were gathered by a structured, open-ended questionnaire. The "tartar control" toothpastes, B and C, resulted in statistically significant (p less than 0.005) higher rates of mucosal reactions (e.g., ulceration, sloughing, erythema, migratory glossitis) than the "non-tartar control" toothpastes A and D. When the oral mucosal reaction rates were adjusted for multiple clinical observations within each subject at the same point in time there was no statistically significant (p greater than 0.05) difference between male (0.25) and female (0.28) subjects. In this study population, the order of preference was observed as toothpaste A greater than D greater than B greater than C. The major reasons for disfavor were burning sensation in toothpastes C (2.4%) and B (4%).

Adult↗
PubMed1988

Studies on fermented corn flour food poisoning in rural areas of China. II. Isolation and identification of causal microorganisms.

Using potato dextrose agar medium, 40 strains of microorganisms were isolated from leftover fermented corn flour samples involved in outbreaks of food poisoning. All strains produced powerful toxins which caused the same intoxication to mice, dogs, and monkeys as the leftover food samples. On the basis of results obtained from the morphology of this bacteria and its colony, from biochemical tests, and from the G-C mole percentage in DNA, the bacteria was identified as Flavobacterium farinofermentans nov. sp. (Meng, Z. and Wang, D.).

Agglutination Tests↗
PubMed1988

Studies on fermented corn flour poisoning in rural areas of China. I. Epidemiology, Clinical Manifestations, and Pathology.

An outbreak of a new type of fatal food poisoning has been reported in different parts of the People's Republic of China. Liver, kidney, heart, and brain were the main target organs, and the overall fatality of intoxicated individuals was 38.2%. Evidence obtained from epidemiological studies and animal tests indicates that the food poisoning was caused by the consumption of homemade fermented corn flour products.

Animals↗
PubMed1987

The effect of copper IUD on microcirculation of blood flow in rabbit uterus.

A survey of the rabbit's normal microcirculation of blood flow volume in the endometrium and myometrium with or without a copper intrauterine device (IUD) was made. It was found through statistical analyses that the IUD stimulated the endometrium so that microcirculation of blood flow volume in the endometrium increased significantly, but it did not change the microcirculation of blood flow volume in the myometrium and in the opposite uterus.

Animals↗