Biomedical subjects

Y Yan

Publications and source records attributed to Y Yan.

At least 127 records · Page 7Linked to original sources

PubMed2000

[Cell cycle analysis and pathological changes of malignant tumors treated with electrochemical therapy].

To investigate the mechanism and to observe the effectiveness of electrochemical therapy(ECT), 33 patients of late stage cancers which treated by ECT were included in this study. Flow cytometry (FCM) and pathology were used to observe the changes of tumor cells before and after ECT. Tumor cells of G1, G2/M, S phases and aneuploid cells were found to be killed almostly and the ratio of apoptosis was elevated greatly after ECT. Also, pathological evidence proved the death of tumor cells and some characters of apoptosis. So, ECT can non-selectively kill tumor cells and induce the apoptosis of them, and FCM was a way to evaluate the effectiveness of ECT.

Adult↗

PubMed2000

[Treatment of nonunion of scaphoid bone by transfer of radial periosteal bone flap pedicled with recurrent branch of radial artery].

OBJECTIVE: To introduce the operation method of treatment of nonunion of scaphoid bone by transfer of pedicled radial periosteal bone flap. METHODS: From Match 1986, 26 cases with old nonunion of scaphoid bone were treated by transfer of radial periosteal bone flap pedicled with recurrent branch of radial artery, the size of bone flap was 1.0 cm x 0.4 cm x 0.5 cm. RESULTS: All patients with old nonunion of scaphoid bone were healed by first intention, bone union was occurred after 2 to 3 months of operation, and wrist joint almost recovered normal function. CONCLUSION: It is an effective operation method to treat nonunion of scaphoid bone.

Adolescent↗

PubMed2000

[Preliminary study on the purification of IL-2].

Interleukin-2 (IL-2) which is produced by T-lymphocytes is a protein molecule with the molecular weight of 15,420-Daltons. It has good functions in curing a lot of diseases such as cancer and AIDS even with a small quantity. A new method for purification of IL-2 by preparative high performance liquid chromatography is described. It was the first time to use hydroxyapatite as the packing to separate IL-2. IL-2 has one disulphide bridge (between 58th Cys and 105th Cys) and one free cysteine. In order to prevent aggregation and formation of wrong disulphide bond, 50 mumol/L Cu2+ and 1.5 mol/L guanidine hydrochloride was used for autoxidation and denaturing. Then we used mainly two chromatographic steps: First, Sephadex G-25 Gel permeation chromatography was used to separate guanidine hydrochloride and small molecules. Second, large scale preparative HPLC was used to separate impure protein from IL-2. Gradient elution was performed with phosphate buffer (pH 6.8). Its purity was examined by SDS-PAGE. Its activity reached 1 x 10(6) U/mg by CTLL-2 cell MTT method. The results showed that it is a suitable method for the large-scale purification of IL-2.

Chromatography, High Pressure Liquid↗

PubMed2000

[Cloning and expression of a resistant Culex gene in Escherichia coli].

Recombinant plasmid pRLB1 was constructed from detoxifying gene B1 of pesticide resistant Culex pipiens quinquefasciatus and from plasmid pRL439 contained the strong promoter PpsbA. The positive clone was identified by digestion and Southern analysis. Expression of recombinant plasmid containing esterase gene was detected. An engineered bacterium possessing high enzyme activity was obtained and immobilized. It can effectively degrade the specific substrate alpha-naphthyl acetate (alpha-NA) and beta-naphthyl of esterase enzyme. Assays showed that pesticide acetofenate (7504 an organic choride pesticide) was degraded by the immobilized cells within one hour.

Animals↗

PubMed2000

[Influences of counterfeits on RAPD results of Semen Cuscutae].

Compared the differences of the RAPD results between pure Semen Cuscutae and 12 commercial samples, it comes into the conclusion that the exiting other sample influences the RAPD results when its content is over 60% and the results is same as its content being under 60%.

Cuscuta↗

PubMed2000

Clinical observation of 126 cases of sutureless phacoemulsification with PMMA intraocular lens implantation.

OBJECTIVE: To observe the safety and effect of sutureless phacoemulsification with PMMA intraocular lens (IOL) implantation. METHODS: One-hundred and twenty-six cases (126 eyes) of sutureless phacoemulsification with PMMA intraocular lens (IOL) implantation were retrospectived and evaluated. The surgeries were performed through a limbal tunnel incision. PMMA IOLs with 5.5 mm or 6.0 mm in diameter were implanted. RESULTS: The follow-up was 3-20 months. Visual acuity of 0.5 or better was obtained in 120 cases (95.2%), and that of 1.0 or better was obtained in 89 cases (70.6%). Intra-operative complications included posterior capsule rupture in 9 cases (7.1%) and iris injury in 7 cases (5.6%). Postoperative complications included early corneal edema in 96 cases (76.2%), transient intraocular pressure elevation in 5 cases (4.3%), remnant of cortex in 1 case and leakage of incision in 1 case. All were properly managed with good results. CONCLUSION: Sutureless phacoemulsification with PMMA IOL implantation is safe even in grass-root hospitals where cataracts are harder.

Aged↗

PubMed2000

[The electron microscopic study of AchR and ultrastructure of neuromuscular junction in recurrent laryngeal nerve reinnervation].

OBJECTIVE: The purpose of this study was to observe the distribution of Acetylcholine receptor (AchR) and ultrastructural changes of the neuromuscular junction after laryngeal reinnervation. METHODS: alpha-bungarotoxin-horseradish peroxidase (alpha-BT-HRP) conjugate electron microscopic immunocytochemical methods and computer analysis of intensity of immunocytochemical reaction were applied to observe the distribution and relative quantity of junctional N-AchR. RESULTS: The results showed that the synaptic nerve terminals and presynaptic membrane were segmentally disrupted and almost disappeared completely and were replaced by Schwann's cells at 3 weeks after neurorrhaphy. At 6 weeks, some of the regenerating axons grew to the neuromuscular junctions and all the muscle fibers were reinnervated at 12 weeks. But the original postsynaptic membranes were only partially in contact with the regenerated nerve terminals. These conditions persisted until 18 weeks after neurorrhaphy, when remyelination was found in the vicinity of the neuromuscular junctions. The N-AchR reaction product on the postsynaptic membrane were increased greatly about 1.28 times more than the normal at 3 weeks after neurorrhaphy. The reactive products decreased greatly which was only 0.47% of that in the normal at 6 weeks. It remained low until 12 weeks after neurorrhaphy, which was 0.72% of the normal side. It increased obviously to 0.83 times of normal sides at 18 weeks and didn't changed there after. CONCLUSION: The state of reinnervation determines the quantity of neuromuscular junctional N-AchR.

Animals↗

PubMed2000

[A reappraisal of hyperbaric oxygenation effect and study on serum malondialdehyde and superoxide dismutase in patients with sudden deafness].

OBJECTIVE: To reappraise the effect of HBO and to observe the changes of malondialdehyde (MDA) and superoxide dismutase (SOD) in serum of the patients with sudden deafness. METHODS: 60 patients were randomly divided into two groups. One was treated with HBO combined with medical treatment (treatment group). The other was only treated with HBO (control group). There were 30 healthy volunteers as health group. RESULTS: After treatment, there was a significant difference (chi 2 = 6.48, P < 0.05) in patient's groups in hearing examination. After treatment, SOD volume in treatment group had significant difference with health group and control group (t = 23.27, P < 0.01; t = 27.17, P < 0.01) respectively. There was a significant difference of SOD volume in treatment group itself before and after treatment course (t = 29.27, P < 0.01). There was no significant difference of SOD volume in control group itself before and after treatment(t = 1.33, P > 0.05). MDA: There was a significant difference between treatment group and control one after the treatment. There was a significant difference (t = 7.28, P < 0.01) in treatment group before and after treatment course. There was not a significant difference (t = 1.24, P > 0.05) between treatment and health group after the treatment course. There was a significant difference (t = 7.09, P < 0.01) between control group and health one after the treatment course. CONCLUSION: There was no satisfied curative effect on sudden deafness with HBO only.

Adult↗

PubMed2000

[The experience with endoscopic natural ostiotomy].

OBJECTIVE: To improve the operative technique of endoscopic middle metal antrostomy. METHODS: One hundred and thirty-five patients with chronic sinusitis were divided into two groups(first stage and second stage groups). All of them had been followed up for more than 6 months. RESULTS: Middle metal antrostomy was performed for 79 patients (158 sides) in the first group. The diameter of middle meatal window ranged from 1.0 cm (anterior-posterior diameter) to 1.5 cm(superior-inferior diameter). Improved middle meatal antrostomy was performed for 56 patients (112 sides) in the second group. The anterior-posterior diameter of the middle meatal window was over 1.0 cm, and superior-inferior diameter was over 1.5 cm. In the first group, the patency rate in the first stage was 78.48% (124/158), and satisfactory patency rate was 43.0% (68/158). The patency rate was 85.4% (135/158), and satisfactory patency rate was 45.0%(71/158). In the second group, the patency rate was 92.9%(104/112) in the first stage, and 94.6%(106/112) in the second stage. The satisfactory patency rate in both stages was 79.5%(89/112). There was significant difference between two groups(P < 0.05). CONCLUSION: The patency rate and satisfactory patency rate of middle meatal antrostomy are increased by improved technique.

Adolescent↗

PubMed2000

[Information technology of modern NIR spectral analysis].

The main points, flowdiagram and the levels of optimization and building models of modern NIRS analysis are described in this paper. The strategy of how to apply and develop the technology of Near-Infrared spectroscopy analysis in our country is also described. In order to develop the technology of NIRS, the Industrialization and Democratization should combined.

Electronic Data Processing↗

PubMed1999

Evidence that apoptosis of activated T cells occurs in spontaneous tolerance of liver allografts and is blocked by manipulations which break tolerance.

BACKGROUND: Fully allogeneic liver grafts from piebald virol glaxo to dark agouti rats are spontaneously tolerated, whereas kidney transplants between these strains are rejected. Liver tolerance is broken by donor irradiation or peritransplant corticosteroid treatment of recipient rats, both of which interfere with the activation of recipient cells. METHODS: In this study we used a combination of immunohistochemical staining, reverse transcription-polymerase chain reaction, and terminal deoxynucleotide transferase-mediated dUTP nick end labeling and Annexin-V apoptosis assays to compare donor cell migration, cytokine profiles, and leukocyte apoptosis in grafts and lymphoid organs from tolerant liver and rejecting kidney recipients. We then examined the effect on apoptosis of treatments which abrogate liver tolerance. RESULTS: Liver transplantation in this tolerant strain combination is accompanied by rapid migration of many passenger leukocytes to the recipient spleen and lymph node, concurrent with a marked but transient increase in the amount of mRNA for the cytokines interleukin-2 and interferon-gamma. Apoptotic cells appear promptly in the spleen, their numbers reaching a peak 2 days earlier than has been previously shown for the graft infiltrate. Both CD4+ and CD8+ T cells undergo apoptosis and apoptotic cells are most concentrated among CD25+ T cells. In contrast, renal transplant rejection is associated with limited donor cell migration to lymphoid tissues and significantly less up-regulation of interleukin-2 and interferon-gamma in the spleen. Few apoptotic cells are detected in spleen or graft infiltrate during rejection, whereas apoptotic renal tubular and glomerular cells are found from day 5. Either recipient steroid treatment or donor irradiation significantly reduced the number of apoptotic cells in liver graft infiltrates and recipient spleen. CONCLUSIONS: Taken together, these findings suggest that a mechanism akin to activation-induced cell death, with apoptosis of alloreactive recipient cells may be responsible for the induction of spontaneous liver transplant tolerance.

Animals↗

PubMed1999

Optimizing computerized treatment planning for the Gamma Knife by source culling.

PURPOSE: A good plan is crucial to the success of gamma knife treatment, which depends not only on parameters such as the number of shots, shot position, collimator sizes, and shot weight, but also on the number of blocked cobalt sources. However, during treatment, a plug is generally used to block those cobalt sources, so the beam cannot reach critical tissues. We present here an automated method to optimize all of those parameters, and to choose a source set, although the beams of some blocked sources do not hit any critical tissue. This strategy is used to achieve a high dose that better conforms to the tumor shape, and at the same time, avoids healthy tissue. METHODS AND MATERIALS: Using a workstation that integrates the gamma knife treatment planning system, we developed a two-step optimization algorithm. First, we used a modified Powell's method to optimize the location of the shot, collimator size, and shot weight; we used simulated annealing to determine if the number of shots was adequate using this parameter. Then, simulated annealing was used to determine which cobalt sources we needed to block. RESULTS: Application of this optimization method in two cases showed that the treatment plan can be much improved when the set of blocked cobalt sources has been taken into consideration. CONCLUSION: Determining the set of blocked sources is necessary in certain cases. This technique better conforms the desired isodose curves to the outline of the target volume and minimizes damage to the surrounding normal tissues.

Algorithms↗

PubMed1999

Studies on the multidrug resistance gene expression in the livers of rats associated with different susceptibility of hepatocarcinogenesis.

Inbred carcinogen-resistant DRH rat strain developed from the closed colony Donryu rats on the basis of selective markers such as poor induction of gamma-glutamyltranspeptidase and marked reduced incidences of liver tumors during 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB) administration, which took more than 10 years. Previously, we observed that the Donryu rat liver was quite sensitive to both DNA-damaging and cytotoxic effects of 3'-Me-DAB, while the DRH rat liver showed tolerance to 3'-Me-DAB under the same conditions. In the present study, we examined mRNA levels related to the cytotoxic drug resistance mechanism in the livers of DRH and Donryu rats using RT-PCR. Contrary to our expectation, we observed rather similar levels of mRNAs between the two rat strains under the following conditions: i) mdr1 mRNA induction after 3'-Me-DAB administration. ii) MLP-2 mRNA reduction by 3'-Me-DAB administration, iii) MLP-2 mRNA induction after cholestasis and iv) constitutive levels of cMOAT gene expression. On the other hand, the levels of p53 mRNA and p53 protein in the Donryu rat liver were higher than those in DRH rat liver during 3'-Me-DAB administration, suggesting that the former were more sensitive to 3'-Me-DAB than DRH rat under these conditions. In conclusion, we failed to demonstrate the difference in the cytotoxic drug resistance mechanism between DRH and Donryu rats at least under the conditions examined in this study.

Animals↗

PubMed1999

Distinct roles for PP1 and PP2A in phosphorylation of the retinoblastoma protein. PP2a regulates the activities of G(1) cyclin-dependent kinases.

The function of the retinoblastoma protein (pRB) in controlling the G(1) to S transition is regulated by phosphorylation and dephosphorylation on serine and threonine residues. While the roles of cyclin-dependent kinases in phosphorylating and inactivating pRB have been characterized in detail, the roles of protein phosphatases in regulating the G(1)/S transition are not as well understood. We used cell-permeable inhibitors of protein phosphatases 1 and 2A to assess the contributions of these phosphatases in regulating cyclin-dependent kinase activity and pRB phosphorylation. Treating asynchronously growing Balb/c 3T3 cells with PP2A-selective concentrations of either okadaic acid or calyculin A caused a time- and dose-dependent decrease in pRB phosphorylation. Okadaic acid and calyculin A had no effect on pRB phosphatase activity even though PP2A was completely inhibited. The decrease in pRB phosphorylation correlated with inhibitor-induced suppression of G(1) cyclin-dependent kinases including CDK2, CDK4, and CDK6. The inhibitors also caused decreases in the levels of cyclin D2 and cyclin E, and induction of the cyclin-dependent kinase inhibitors p21(Cip1) and p27(Kip1). The decrease in cyclin-dependent kinase activities were not dependent on induction of cyclin-dependent kinase inhibitors since CDK inhibition still occurred in the presence of actinomycin D or cycloheximide. In contrast, selective inhibition of protein phosphatase 1 with tautomycin inhibited pRB phosphatase activity and maintained pRB in a highly phosphorylated state. The results show that protein phosphatase 1 and protein phosphatase 2A, or 2A-like phosphatases, play distinct roles in regulating pRB function. Protein phosphatase 1 is associated with the direct dephosphorylation of pRB while protein phosphatase 2A is involved in pathways regulating G(1) cyclin-dependent kinase activity.

3T3 Cells↗

PubMed1999

The occurrence of polymorphism of mannose 6-phosphate/insulin-like growth factor 2 receptor gene in laboratory and wild rats.

Carcinogen-resistant inbred DRH rat strain was established from closed colony Donryu rats in the presence of 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB). Despite using 3'-Me-DAB during the stage of selection, the DRH rats developed normally and did not show any spontaneous tumor at over 1 year of age. In the present study, we examined the polymorphism in mannose 6-phosphate/insulin-like growth factor 2 receptor (M6p/Igf2r) gene and found that the DRH rat showed CCC (Proline)-type polymorphism in exon 48 and the Donryu rat had GCC (Alanine) sequence. Since the DRH rat was developed from the Donryu rat, we examined whether this polymorphism in exon 48 of M6p/Igf2r gene was due to mutation that occurred at the stage of selection in the presence of 3'-Me-DAB, using several other laboratory and wild rats. We detected the presence of polymorphism at the same site of the M6p/Igf2r gene among these rats. It is likely that the polymorphism in exon 48 of the M6p/Igf2r gene is present broadly in rats since ancient times and not due to the mutation during the course of selection unless this site is a hot spot for chemical carcinogens.

Alanine↗

PubMed1999

The effects of phytoestrogens on human pancreatic tumor cells in vitro.

Diet has been implicated as a possible link to the etiology, promotion and/or progression of many diseases, including cancer. Recently, interest has been focused on the cancer-protective role of several of the hormone-like diphenolic phytoestrogens, lignans, and isoflavonoids. This study examined the chemoprotective effects of genistein, biochanin A, equol, and coumestrol on human pancreatic adenocarcinoma cells in vitro. Two human adenocarcinoma cell lines, HPAF-11 from a male and Su 86.86 from a female, were used. HPAF-11 cells were exposed for 24 h to these agents at concentrations of 1 and 10 microM. Su 86.86 cells were exposed for 24 h at a concentration of 1 microM. Coumestrol and equol at higher concentrations were toxic to the Su 86.86 cells. These agents displayed marked differences between cell lines in inhibition of growth. Equol and coumestrol inhibited the growth of the female pancreatic tumor cells by 95%; however, these agents stimulated the growth of pancreatic tumor cells from the male. Genistein also stimulated growth in the male pancreatic tumor cells, but had little effect on pancreatic tumor cells from the female. Biochanin A inhibited growth of both male and female tumor cells, but to a lesser extent than other agents. This study also indicated a difference in K-ras expression in pancreatic tumors cells treated with these agents. Equol and coumestrol decreased K-ras expression in the female tumor cell line. Genistein increased expression of K-ras in both male and female pancreatic tumor cells. Genistein also increased expressions of the multidrug resistant (mdr-1) gene in the male tumor-cell line, while coumestrol and biochanin A decreased expression. Equol had no effect on mdr-1 expression. Whether the chemoprotective potential of equol and coumestrol against pancreatic cancer is greater in females than males is being further studied.

Analysis of Variance↗

PubMed1999

Genetic properties for the suppression of development of putative preneoplastic glutathione S-transferase placental form-positive foci in the liver of carcinogen-resistant DRH strain rats.

The post-initiation stage of hepatocarcinogenesis was investigated in carcinogen-resistant inbred DRH rats and the parental strain, carcinogen-sensitive Donryu rats. Male rats at 5 weeks of age from both strains were treated with N-nitrosodiethylamine (200 mg/kg i.p.) followed by feeding with a diet containing 3'-methyl-4-dimethylaminoazobenzene (3'-Me-DAB) from 2 weeks later and were then subjected to partial hepatectomy at 1 week later. At 8 weeks after the start of treatment, the mean area occupied by glutathione S-transferase placental form (GST-P)-positive lesions was about 30% in Donryu rats but less than 4% in DRH rats despite the presence of comparable numbers of foci in the livers of both strains. These observations suggested that clonal expansion of GST-P-positive foci in DRH rat liver was significantly suppressed under these conditions. Furthermore, this genetic property was dominantly inherited in the F1 rats by crosses of DRH and carcinogen-sensitive inbred F344 rats; that is, the induction of GST-P mRNA in the livers of F344 x DRH F1 rats was dominantly suppressed after administration of 3'-Me-DAB for 8 weeks as compared with parental F344 rats under the same conditions. We compared the intrinsic properties related to growth potential of liver cells between adult DRH and Donryu rats. DRH rat liver showed retarded and/or reduced DNA synthesis after partial hepatectomy or a single i.v. injection of lead nitrate and lower activity of telomerase induced by 3'-Me-DAB administration for 1 week, as compared with the Donryu rat liver. The intrinsic properties observed in this study may be related, at least in part, to the low incidence of liver tumors induced by hepatocarcinogens in DRH rats.

Animals↗

PubMed1999

Simultaneous enantiomeric determination of dansyl-D,L-phenylalanine by fluorescence spectroscopy in the presence of alpha-acid glycoprotein.

Few techniques are amenable to real-time analysis of enantiomers. In this paper, total complexation by alpha-acid glycoprotein (AGP) is shown to discriminate between enantiomers of dansyl-D,L-phenylalanine (DPs) by changing the local environment of the D and L enantiomers (DDP and DLP, respectively) from hydrophilic to hydrophobic. DDP and DLP show the same native fluorescence at lambda ex/lambda em = 200/544 nm in the absence of AGP, but show shifted emissions with a component at lambda ex/lambda em = 220/497 nm in the presence of AGP and in lipophilic solutions. The conditions for an analytical determination have been optimized, and the method has been used to measure the enantiomeric composition of DDP/DLP mixtures with concentration ratios varying over 2 orders of magnitude. The mechanism of chiral recognition for DDP and DLP by AGP is discussed and should be equally applicable to other dansyl-derivative amino acid enantiomers. The association constants for AGP with DDP and with DLP have been determined to be 1.33 x 10(2) L g-1 and 2.29 x 10(2) L g-1, respectively.

Animals↗