Biomedical subjects

Y Feng

Publications and source records attributed to Y Feng.

At least 181 records · Page 10Linked to original sources

PubMed1999

Capability of serum to convert streptomycin to cytotoxin in patients with aminoglycoside-induced hearing loss.

Individual variations in sensitivity to the ototoxic effects of aminoglycoside antibiotics are well documented. Our research demonstrates that there is an apparent difference in serum from patients who are resistant or susceptible to aminoglycoside ototoxicity. In the first study, the cytotoxicity of sera from patients with and without hearing loss after various time periods following the discontinuation of aminoglycoside treatment was assayed using the isolated outer hair cell toxicity assay. The results indicate that sera from patients with hearing loss were significantly more toxic than sera from patients with normal hearing or minimal hearing loss. This toxicity may persist for up to 1 year after discontinuation of aminoglycoside therapy. In a second study, sera were obtained from patients who had received aminoglycoside therapy several years previously. None of these sera was toxic to isolated outer hair cells in vitro. Streptomycin was then incubated with the sera or a protein fraction isolated from sera, and the incubation mixtures were tested for toxicity. The percentage of damaged outer hair cells was significantly higher when streptomycin had been treated with sera or a serum protein fraction from patients with hearing loss (58+/-10% and 68+/-9%, respectively) than with sera or a serum protein fraction from a control group (10+/-5% and 17+/-4%, respectively). In addition, several incubation mixtures were analyzed using high performance liquid chromatography. A new chromatographic peak was only found in the incubations of streptomycin with serum protein from patients with hearing loss. The results suggest that sera from individuals sensitive to aminoglycoside antibiotics may metabolize these drugs to cytotoxins.

Adolescent↗

PubMed1999

Distributions of lead and cadmium in dust in the vicinity of a sewage sludge incinerator.

The content of lead and cadmium in surface dust within a 4 km radius of a sewage sludge incinerator has been investigated. Particular attention was given to Pb and Cd in different size fractions of dust, an aspect not explored in previous studies, and the differences between expressions of contamination as concentration or loading were examined. Despite suggestions from reports that sludge incinerators may have difficulty in complying with emission standards, the present investigation found little evidence for a major contribution to local pollution by the incinerator. Certainly, the highest Cd level was found some 2.2 km downwind of the prevailing wind direction from the incinerator, suggesting some resultant contamination, although the levels do not appear to be excessive. Similar observations apply to Pb contamination of the area. While data of the type produced in this study contribute to an understanding of environmental quality, both loadings and levels need to be considered, as the implications of only consideration one of these may be limited and even misleading.

Air Pollution↗

PubMed1999

The chemical form of selenium influences 3,2'-dimethyl-4-aminobiphenyl-DNA adduct formation in rat colon.

There is increasing evidence that selenium can protect against tumorigenesis or preneoplastic lesion development induced by chemical carcinogens. This study examined whether selenite, selenate or selenomethionine would be protective against 3, 2'-dimethyl-4-aminobiphenyl (DMABP)-DNA adduct formation in the liver and colon of rats and sought to delineate the mechanism for the protective effects of the different chemical forms of selenium against aberrant crypt formation, a preneoplastic lesion for colon cancer. After injection of DMABP, two DNA adducts were identified in the liver and colon of rats. Supplementation with either 0.1 or 2.0 mg selenium/kg diet as either selenite or selenate but not selenomethionine resulted in significantly fewer (53-70%; P < 0.05) N-(deoxyguanosin-8-yl)-(deoxyguanosin-8-yl)-3, 2'-dimethyl-4-aminobiphenyl (C8-DMABP)-DNA adducts in the colon but not the liver than in rats fed a selenium-deficient diet. Rats supplemented with selenomethionine had greater (P < 0.05) plasma and liver selenium concentrations and glutathione peroxidase activity than those supplemented with selenite or selenate; however, they also had more DMABP-DNA adducts. The protective effect of selenite and selenate against DMABP-DNA adduct formation apparently is not a result of alterations in plasma or liver selenium concentrations or altered glutathione peroxidase or glutathione transferase activities but may be related to differences in the metabolism of the different forms of selenium.

Aminobiphenyl Compounds↗

PubMed1999

Dietary copper, manganese and iron affect the formation of aberrant crypts in colon of rats administered 3,2'-dimethyl-4-aminobiphenyl.

Aberrant crypt foci (ACF) are preneoplastic lesions for colon cancer. Altered amounts of copper-zinc (CuZnSOD) and manganese (MnSOD) superoxide dismutases have been implicated in multistage carcinogesis of both rodents and humans. Dietary factors are potential modulators of both CuZnSOD and MnSOD activity. The purpose of this study was to investigate the interactive effects of dietary copper, manganese, and iron on 3,2'-dimethyl-4-aminobiphenyl (DMABP)-induced ACF and superoxide dismutase activities in weanling rats fed low or adequate copper (0.8 or 5.1 microg Cu/g diet), low or adequate manganese (0.6 or 17 microg Mn/g diet), and adequate or high iron (37 or 140 microg Fe/g diet). Twelve rats were allowed free access to each of these eight diets for 3.5 wk prior to DMABP administration and for an additional 8 wk after the first DMABP injection. Rats fed low dietary copper had 105% (P < 0.0001) higher formation of DMABP-induced ACF than those fed adequate dietary copper. Rats ingesting low rather than adequate dietary manganese had 23% higher formation of ACF, and rats ingesting high rather than adequate dietary iron had 18% higher formation of ACF. Heart total superoxide dismutase activity was significantly correlated with the number of ACF (r = -0.43, P < 0.0001) in rats administered DMABP. These results suggest that dietary alterations that affect superoxide dismutase activity may affect cancer susceptibility.

Aminobiphenyl Compounds↗

PubMed1999

Purification and characterization of gentisate 1,2-dioxygenases from Pseudomonas alcaligenes NCIB 9867 and Pseudomonas putida NCIB 9869.

Two 3-hydroxybenzoate-inducible gentisate 1,2-dioxygenases were purified to homogeneity from Pseudomonas alcaligenes NCIB 9867 (P25X) and Pseudomonas putida NCIB 9869 (P35X), respectively. The estimated molecular mass of the purified P25X gentisate 1, 2-dioxygenase was 154 kDa, with a subunit mass of 39 kDa. Its structure is deduced to be a tetramer. The pI of this enzyme was established to be 4.8 to 5.0. The subunit mass of P35X gentisate 1, 2-dioxygenase was 41 kDa, and this enzyme was deduced to exist as a dimer, with a native molecular mass of about 82 kDa. The pI of P35X gentisate 1,2-dioxygenase was around 4.6 to 4.8. Both of the gentisate 1,2-dioxygenases exhibited typical saturation kinetics and had apparent Kms of 92 and 143 microM for gentisate, respectively. Broad substrate specificities were exhibited towards alkyl and halogenated gentisate analogs. Both enzymes had similar kinetic turnover characteristics for gentisate, with kcat/Km values of 44.08 x 10(4) s-1 M-1 for the P25X enzyme and 39.34 x 10(4) s-1 M-1 for the P35X enzyme. Higher kcat/Km values were expressed by both enzymes against the substituted gentisates. Significant differences were observed between the N-terminal sequences of the first 23 amino acid residues of the P25X and P35X gentisate 1,2-dioxygenases. The P25X gentisate 1,2-dioxygenase was stable between pH 5.0 and 7.5, with the optimal pH around 8.0. The P35X enzyme showed a pH stability range between 7.0 and 9.0, and the optimum pH was also 8.0. The optimal temperature for both P25X and P35X gentisate 1, 2-dioxygenases was around 50 degrees C, but the P35X enzyme was more heat stable than that from P25X. Both enzymes were strongly stimulated by 0.1 mM Fe2+ but were completely inhibited by the presence of 5 mM Cu2+. Partial inhibition of both enzymes was also observed with 5 mM Mn2+, Zn2+, and EDTA.

Amino Acid Sequence↗

PubMed1999

Comparative study of viscerosomatic input onto postsynaptic dorsal column and spinothalamic tract neurons in the primate.

The purpose of the present investigation was to examine, in the primate, the role of the postsynaptic dorsal column (PSDC) system and that of the spinothalamic tract (STT) in viscerosensory processing by comparing the responses of neurons in these pathways to colorectal distension (CRD). Experiments were done on four anesthetized male monkeys (Macaca fascicularis). Extracellular recordings were made from a total of 100 neurons randomly located in the L(6)-S(1) segments of the spinal cord. Most of these neurons had cutaneous receptive fields in the perineal area, on the hind limbs or on the rump. Forty-eight percent were PSDC neurons activated antidromically from the upper cervical dorsal column or the nucleus gracilis, 17% were STT neurons activated antidromically from the thalamus, and 35% were unidentified. Twenty-one PSDC neurons, located mostly near the central canal, were excited by CRD and three were inhibited. Twenty-four PSDC neurons, mostly located in the nucleus proprius, did not respond to CRD. Of the 17 STT neurons, 7 neurons were excited by CRD, 4 neurons were inhibited, and 6 neurons did not respond to CRD. Of the unidentified neurons, 23 were excited by CRD, 7 were inhibited, and 5 did not respond. The average responses of STT and PSDC neurons excited by CRD were comparable in magnitude and duration. These results suggest that the major role of the PSDC pathway in viscerosensory processing may be due to a quantitative rather than a qualitative neuronal dominance over the STT.

Animals↗

PubMed1999

Regional correlation between estimated UVB levels and skin cancer mortality in Japan.

Most ecological studies investigating the relationship between incidence and/or mortality of skin cancer and surrogate measures of ultraviolet radiation B (UVB) have been conducted among the Caucasian population. The objective of the present study was therefore to assess the geographical correlation between ambient UVB estimates and regional mortality rates for skin cancer in Japan. The standardized mortality ratio (SMR) for malignant melanoma and other malignant neoplasms of the skin was calculated by sex, region and time-period for all deaths occurring in the period 1973-1994. The Spearman's correlation coefficient was calculated between estimated ambient UVB and regional SMRs for the two types of skin cancer. There was no geographical correlation between UVB and skin cancer mortality, except for a significantly negative correlation in malignant melanoma among males and a significantly negative correlation in other malignant neoplasms of the skin confined to unexposed anatomic sites of the body among females. The characteristic ecological relationship adds to the importance of conducting further epidemiological studies at the individual level in Japan.

Age Distribution↗

PubMed1999

Periaqueductal gray stimulation-induced inhibition of nociceptive dorsal horn neurons in rats is associated with the release of norepinephrine, serotonin, and amino acids.

The stimulation of the periaqueductal gray (PAG) produces behavioral analgesia in rats, cats, monkeys, and humans. This analgesia is believed to be mediated by several neurotransmitter systems, including the serotonergic, noradrenergic, glycinergic, gamma-aminobutyric acidergic, and opiatergic systems. The present study was designed to determine whether PAG stimulation produces the release of serotonin (5-HT), norepinephrine (NE), Gly, and gamma-aminobutyric acid in the spinal cord dorsal horn and whether the release of these neurotransmitters by PAG stimulation is associated with a long-lasting inhibition of the evoked nociceptive responses of dorsal horn neurons. The effect of different frequencies of stimuli on the release of neurotransmitters in the spinal cord was also examined. Microdialysis in combination with HPLC was used to measure the concentrations of neurotransmitters in the lumbar dorsal horn before, during, and after electrical stimulation of the PAG. The PAG was stimulated with electrical pulses at 333 Hz first and then at 67 Hz with the same intensity for 27 min, respectively. Both stimulus frequencies produced a significant increase in the release of 5-HT, NE, Gly, and Asp in the spinal dialysate, but the low-frequency stimulus was more potent in causing the release of neurotransmitters. Low-frequency stimulation also significantly increased the release of Glu. The time course of inhibition of dorsal horn neurons induced by long-lasting PAG stimulation corresponded to the time course of neurotransmitter release. Therefore, the results suggest that the long-lasting inhibition induced by PAG stimulation is mediated in part by the release of 5-HT, NE, and inhibitory amino acids in the spinal cord.

Amino Acids↗

PubMed1999

[Evaluation of screening methods for cholinesterase variants from daily laboratory data].

The genetic variants of the cholinesterase (ChE) are frequently misdiagnosed as a liver dysfunction. We compared three extraction methods for screening of ChE abnormalities. Employing these three methods, total 31 cases were found to be genetic abnormalities from 2985 patients of Hamamatsu University Hospital. We picked up 11 of candidates with low enzyme activities less than 100U/l as group 1 using the first method and effectively detected 9 cases (82%) with genetic abnormalities. The second extraction method was based on the ratio between Albumin (Alb) and ChE and subsequently, 48 of high risk patients were picked up as group 2 and 28 cases (58%) showed genetic abnormalities. Furthermore, all cases of group 1 were contained in the second group. The third method was based on the discrimination function from Alb and total cholesterol (TC) as group 3 and 32 cases were picked up. Fourteen cases (44%) out of them showed the genetic abnormalities using this method, and surprisingly, 13 cases (93%) of them were estimated to be K-variant. Although the three methods showed the different characteristics to extract genetic abnormalities of ChE, the second extraction method could pick up the largest population with genetic abnormalities. Further phenotypic extraction methods should be compared to understand the relationship between phenotype and genotype.

Cholesterol↗

PubMed1999

[Effect of liposome-C-erbB2 antisense oligodeoxynucleotides on the growth and the chemotherapeutic drug sensitivity of human ovarian cancer transplanted in the omentum of nude mice].

OBJECTIVE: To investigate the effects of liposome-C-erbB2 antisense phosphorothioate oligodeoxynucleotides(S-ODNs) on the growth and the chemotherapeutic drug sensitivity of human ovarian cancer transplanted in the omentum of nude mice. METHODS: Human ovarian cancer transplanted in the omentum of nude mice model was established, then divided into four groups: control group, experimental group, chemotherapeutic group, and experimental + chemotherapeutic group. Different treatments were given respectively. The weight of nude mice was observed and the morphology of tumor cells was observed by electromicroscope. RESULTS: The growth inhibitory rate in the experimental group was 37%. There were more heterochromatins in the treated tumor cells. The growth inhibitory rate in the experimental + chemotherapeutic group was increased to 50%. There was no obvious alteration in the weight of experimental group. CONCLUSION: The data in this study suggest that antisense therapy is an useful method of gene therapy in ovarian cancer; Moreover, it could enhance the effectiveness of antitumor drug.

Animals↗

PubMed1999

[Effect of liposome-C-erbB2 antisense oligodeoxynucleotides on human ovarian cancer cells].

OBJECTIVE: To explore the effects of liposome-C-erbB2 antisense phosphorothioate oligo deoxynucleotides(S-ODNs) on C-erbB2 protooncogene expression and cell proliferation in human ovarian cancer cells. METHODS: The effects on C-erbB2 protooncogene expression, cell proliferation and cell cycle in human ovarian cancer cells were studied by flow cytometry and 3H-thymidine incorporation. RESULTS: Liposome-C-erbB2 S-ODNs could reduce C-erbB2 expression and inhibit cell proliferation in human ovarian cancer cells; the effectiveness of liposome-C-erbB2 S-ODNs on the expression of C-erbB2 was much higher than that of C-erbB2 S-ODNs, about 40 times. CONCLUSIONS: The data in this study suggest that antisense therapy is an useful method of gene therapy in ovarian cancer. The effectiveness of C-erbB2 S-ODNs could be greatly increased by C-erbB2 S-ODNs encapsulated in liposomes.

Cystadenocarcinoma, Papillary↗

PubMed1999

[Transvaginal gamete intrafallopian transfer: an analysis of 42 cases].

OBJECTIVE: To develop the technique of transvaginal gamete intrafallopian transfer (TV-GIFT) and to evaluate its effectiveness. METHODS: From May, 1996 to October, 1997, 42 infertile patients with at least one tube patent, proven by hysterosalpingography were included. In 43 cycles, ovarian stimulation was performed by using follicle-stimulating hormone (FSH), human menopausal gonadotropin (hMG)/hCG or hMG/hCG program. Oocytes retrieval was performed by transvaginal ultrasound guided needle aspiration. Semen samples were prepared by modified swim-up method. The Jansen-Andersen tubal catheter was introduced into a fallopian tube transvaginally, and the gametes were injected into the tube. RESULTS: Transvaginal cannulation was successfully performed in 67.4% of cases. The mean number of oocytes transferred was 4.0 +/- 0.9 (2-6) per cycle. 13 cases obtained clinical pregnancy (30.2% per cycle), 9 given birth with 5 twin pregnancies (altogether 13 babies), 4 spontaneous abortions. CONCLUSIONS: TV-GIFT offers an acceptable pregnancy rate for patient with at least one patent tube. The procedure is simple and easy to perform and therefore, is worth to recommend for the treatment of infertility.

Adult↗

PubMed1999

[Influences of gestational hyperglycemia on the function of fetal rat pancreatic islets].

OBJECTIVE: To investigate the influences of gestational hyperglycemia on the function of fetal rat pancreatic islets. METHODS: Twenty-eight pregnant SD rats were randomly allocated into two groups. The study group was continually infused with 30% glucose at the rate of 2 ml/min, while the controls with sterilized distilled water in the same time and at the same rate. The infusion began on day 16.5 post-coitus and lasted for 5 days until the removal of the fetuses. The functions of the beta-cells in fetal rat islets were studied by determining the content of insulin, using the tests of extracting, releasing and perfusing. RESULTS: The data showed that the insulin content of study group (3,329.81 +/- 163.39) ng was significantly higher than that of controls (2,390.04 +/- 151.39) ng (P < 0.05); After 2 hours' incubation in Hanks solution which contained different concentration of glucose, increased insulin secretion was found in the study group (P < 0.05); When the islets were perfused, the insulin peak value of study group was higher and appeared earlier than that of controls. CONCLUSION: Insulin synthesis and secretion function of beta-cells of fetal pancreas from hyperglycemia rats were enhanced and the pancreas had a hypersensitive response to glucose challenge.

Animals↗

PubMed1999

[Effects of synthetic peptides on ovarian cancer cells].

OBJECTIVE: To observe the effect of follicle-stimulating hormone(FSH) synthetic peptides(FSH binding Fragment), FSH and synthetic peptides on the proliferation of human epithelial ovarian cancer cell. METHODS: Human epithelial ovarian cancer cells lines SKOV3, OVCAR, AO and 3AO were incubated with FSH, FSH binding fragment, FSH and the binding fragment respectively. The cell proliferation was detected by methyl thiazolyl tetrazolium (MTT) technique. RESULTS: The rate of proliferation in the cancer cell was increased apparently as increasing in the concentration of FSH and the rate of proliferation average value 28.0%, and was decreased apparently as increasing in the concentration of the synthetic peptides and the rate of inhibition average value 8.3%. When the cell was expressed in FSH, the proliferation was decreased apparently as increasing in the concentration of the peptides and the rate of inhibition average valve 3.1%. CONCLUSIONS: It is suggested that FSH binding fragment can inhibit the proliferation of ovarian cancer cell. The FSH binding fragment could be used as a binding part of anticancerous complex for ovarian cancer.

Dose-Response Relationship, Drug↗

PubMed1999

Proliferative activity in cervical intraepithelial neoplasia and cervical carcinoma.

OBJECTIVE: To detect the proliferative activity of cervical cells in cervical intraepithelial neoplasia (CIN) and cervical carcinoma by using proliferating cell nuclear antigen (PCNA) immunohistochemistry and mitotic index (MI). METHODS: Sixty specimens of CIN and cervical carcinoma from patients treated at the Obstetrics and Gynaecology Hospital, Shanghai Medical University, were analyzed. Among them, 8 were CIN I-II, 16 CIN III, 18 squamous carcinoma, and 18 adenocarcinoma. Serial 4 microns sections were prepared for haematoxylin and eosin (HE) staining to observe mitotic figure and pathological grading and for immunohistochemical staining of PACN which was performed by murine monoclonal antibody PC 10 (DAKO-PCNA). RESULTS: PCNA index (PI) and MI of CIN III and cervical carcinoma were significantly higher than those of normal cervix and CIN I-II. PI and MI increased with progress of disease. In addition, higher level of PI was correlated with higher level of MI, and higher levels of PI and MI were related with higher histological grade. However, there was no significant relationship between PI, MI, clinical staging, and lymph node metastases. CONCLUSION: PCNA and mitotic figure are useful for evaluating proliferative activity in CIN and cervical carcinoma, and could be used to distinguish CIN III from CIN I-II and evaluate the malignant potential of tumour tissues.

Adenocarcinoma↗

PubMed1999

[The relation-ship between apoptosis, apoptosis related-gene expression and proliferative activity in smooth muscle cell after autogenous vein grafting].

OBJECTIVE: To study the mechanism of graft vein stenosis. METHODS: A rat experimental model of autogenous vein graft was established by transplanting the right external jungular vein into the infrarenal abdominal aorta in 100 Wister rats. Electric microscope, TUNEL and immunohistochemical S-P technique were used to detect the apoptosis, the expression of apoptosis related-gene bcl-2 and bax and proliferation cell nuclear antigen (PCNA) of smooth muscle cells(SMCs) in vein graft. RESULTS: From 1 to 8 weeks after replacement, the expression of apoptosis and PCNA of SMCs was continuously higher than the control group (P < 0.01). From 1 to 2 weeks, the expression of TUNEL and PCNA showed peak value. From 1 to 2 weeks, the positive rate of apoptosis was lower than that of PCNA, but from 4 to 8 weeks, the positive rate of TUNEL was higher than that of PCNA. There was obvious positive correlation between the expression of TUNEL and PCNA (r = 0.813 P < 0.05). One to 2 weeks after vein grafting, bcl-2 positive rate increased and was more different than the control group and the group of 4 to 8 weeks after vein grafting (P < 0.010). CONCLUSIONS: The imbalance of proliferation and apoptosis may be related to the vessel remodeling and vein graft stenosis, and bcl-2 and bax protein may involve in the regulation of apoptosis of VSMC. Adopting the mixed strategy to regulate the balance between proliferation and apoptosis may be useful to prevent vein graft stenosis.

Animals↗

PubMed1999

[Functional expression of human GM-CSF receptor in NIH3T3 cells].

OBJECTIVE: To characterize human GM-CSF receptor(GM-R) reconstituted in NIH3T3 cells. METHODS: Mouse NIH3T3 cells which do not express human GM-R were transfected with cDNAs encoding the alpha and beta subunit of the human GM-R, and then ligand-stimulated proliferative signal transduction and tyrosine phosphorylation of the positive transfectants were examined. RESULTS: The reconstituted functional receptor, GM-R alpha/beta, could mediate cell proliferation and colony formation in soft agar, and induce tyrosine phosphorylation of beta c, Jak2, Shc and Shc-associated P145(SHIP). However, human GM-CSF did not activate mitogenic signal expression of NIH3T3 cells transfected with GM-R alpha alone. CONCLUSIONS: Introduction of both alpha and beta subunit of human GM-R into NIH3T3 cells can result in ligand-dependent cell growth and colony formation via phosphorylation of beta c and activation of Jak2, Shc and SHIP signal transduction pathway.

3T3 Cells↗

PubMed1999

[Multivariate analysis of prognostic factors after hepatectomy for primary liver cancer].

OBJECTIVE: To determine the prognostic factors for primary liver cancer (PLC) after hepatectomy. METHODS: 182 patients who underwent hepatectomy for PLC from 1988 to 1996 were included for univariate and Cox multivariate analysis. 20 factors contributed to the long-term survival rate (SR) and the disease-free SR were analysed. RESULTS: The cumulative SR (n = 182) in 5 years was 43.3%. The 5-year SR and disease-free SR in the curative resection (CR) group (n = 156) were 48.0%, 24.9%, respectively. Multivariate analysis revealed that classification of CR and differentiation grade were significant factors for the long-term SR, and classification of CR and Child-Pugh's classification were significant factors for the disease-free SR. The 5-year SR and disease-free SR for pathological CR, clinical CR and non-CR (palliative resection) groups were 61.1%, 20.4%, 0 and 28.8%, 15.5%, 0, respectively. CONCLUSIONS: The classification of CR is the determining prognostic factor. Pathological CR is the first option for patients with requirements. To control liver disease and improve adjuvant therapy are essential to decreasing the recurrence and metastasis rates.

Adolescent↗