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Biomedical subjects

K Sun

Publications and source records attributed to K Sun.

At least 109 records · Page 6Linked to original sources
PubMed1998

Regulation of 11beta-hydroxysteroid dehydrogenase type 2 by progesterone, estrogen, and the cyclic adenosine 5'-monophosphate pathway in cultured human placental and chorionic trophoblasts.

Human placenta and fetal membranes contain two types of 11beta-hydroxysteroid dehydrogenase (11beta-HSD). 11Beta-HSD1 interconverts cortisol and cortisone and is the predominant isoform found in the fetal membranes. 11Beta-HSD2, which predominates in the placenta syncytiotrophoblast, converts cortisol to cortisone. It has been proposed that placental 11beta-HSD protects the fetus from high levels of maternal glucocorticoids. In this study, cultured term human placental and chorionic trophoblasts were used to examine the regulation of 11beta-HSD1 and 11beta-HSD2 activities and mRNA expression by progesterone, estrogen, and activators of adenylate cyclase (forskolin) and protein kinase C (phorbol 12-myristate 13-acetate, PMA). Placental trophoblast displayed mainly type 2 oxidase activities. 11Beta-HSD in the chorionic trophoblast was exclusively an 11beta-HSD1 reductase. Progesterone (0.001-1 microM) inhibited 11beta-HSD2 activity in a dose-dependent fashion. Inhibition of endogenous progesterone production with trilostane enhanced 11beta-HSD2 activity. The inhibitory effect of progesterone on 11beta-HSD2 activity was not reversed by the progesterone receptor antagonists RU-486 or onapristone. Progesterone (1 microM) also reduced levels of 11beta-HSD2 mRNA, an effect that was attenuated by both RU-486 and onapristone. Estradiol (1 microM) inhibited type 2 oxidase activity as well. Activation of adenylate cyclase by forskolin (100 microM) up-regulated both 11beta-HSD2 activity and mRNA expression; there was no effect of PMA (1 microM) on 11beta-HSD2. 11Beta-HSD1 reductase activity was unaffected by progesterone, estrogen, forskolin, or PMA in either the placental or chorionic trophoblasts. We conclude that both progesterone and estrogen are inhibitors of 11beta-HSD2 activity in term human placenta in vitro. Levels of 11beta-HSD2 activity and mRNA are increased by activation of the cAMP pathway. Progesterone also suppresses levels of 11beta-HSD2 mRNA.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1998

Double-blind and placebo-controlled study of lithium for adolescent bipolar disorders with secondary substance dependency.

OBJECTIVE: To perform a double-blind, placebo-controlled, random assignment, parallel group, pharmacokinetically dosed study of lithium for adolescents with bipolar disorders (BP) and temporally secondary substance dependency disorders (SDD). METHOD: Subjects were 16.3 +/- 1.2 years old and were comprehensively assessed during a 6-week outpatient protocol that included random weekly urine collection for drug assays and random and weekly serum collection for lithium levels. RESULTS: Using both intent-to-treat (N = 25) and completer (n = 21) analyses, there were significant differences on continuous and categorical measures between the active and placebo groups for both psychopathology measures and weekly random urine drug assays. The mean scheduled weekly serum lithium level of active responders was 0.9 mEq/L. Addiction to both alcohol and marijuana was the most frequent category of SDD. Mean age at onset of BP was 9.6 +/- 3.9 years and of SDD was 15.3 +/- 1.3 years. There were multigenerational mood disorders in 96% and multigenerational SDD in 56% of families. CONCLUSIONS: Lithium treatment of BP with secondary SDD in adolescents was an efficacious treatment for both disorders. These results warrant replication with a long-term maintenance phase. The mean 6-year interval between the onset of BP and onset of SDD strongly argues for earliest recognition of BP.

Adolescent↗
PubMed1998

[Nasal inverted papilloma and human papilloma virus].

In order to elucidate the relationship of human papilloma virus (HPV) infection and pathogenesis of nasal inverted papilloma (IP) and its malignant transformation, 36 cases of IP and 16 cases IP with squamous cell carcinoma (IP + SCC) were detected for HPV related sequence with Polymerase Chain Reaction (PCR) method. HPV related sequence were found in 21 of 36 (58.3%) cases of IP and in 11 of 16 (68.8%) cases of IP + SCC. The difference of positive rates of HPV in IP and IP + SCC were not significant statistically. The results suggested that HPV infection may play an important role in the pathogenesis of IP, and other factor(s) may be needed in the IP malignant transformation in addition to HPV infection.

Carcinoma, Squamous Cell↗
PubMed1998

Visco-supplementation therapy in internal derangement of temporomandibular joint.

OBJECTIVE: To study if visco-supplementation therapy is useful to the internal derangement (ID) of temporomandibular joint (TMJ). METHODS: Sixty-three ID cases (69 TMJs) were studied by visco-supplementation therapy. The upper and/or lower articular cavities were irrigated with 5 ml normal saline and injected 0.3-1.0 ml 1% hyaluronate (HA) into articular cavity. If the symptoms of the disease still existed one week later, the therapy should be repeated for 1-2 times, once a week. The control group cases were injected 1 ml 2% lidocaine instead of HA. 8 other TMJs of 6 ID cases and 2 normal cadavers were studied with scanning electron microscopy (SEM) and light microscopy (LM). RESULTS: The visco-supplement therapy was useful to ID patients. The difference between the test group and control group had statistical significance (chi 2 = 6.6535, P < 0.01). SEM and LM showed that the condyle, disc and bilaminar region in ID were degenerated or destroyed. CONCLUSIONS: The friction between the articular surfaces in ID was increased and the bilaminar region could not retract the disc as in healthy TMJ. The visco-supplementation therapy can decrease the friction and resume the normal rheology of the diseased TMJs.

Adolescent↗
PubMed1998

Mechanism of allyl chloride-induced cytoskeletal injury to nerve cells.

OBJECTIVE: To dissect the molecular mechanism of toxic neuropathy induced by allyl chloride (AC). METHODS: Fluorescence molecular probe (Fura-2/AM), electron probe X-ray microprobe analysis (EPMA) and biochemical methods were used to determine the concentrations of cytosolic free Ca2+, the contents of intracellular Ca2+ percentage, Ca(2+)-free calmodulin (CaM), the activity of Ca2+/CaM-dependent protein kinase II (Ca2+/CaM-PK II), and cytoskeletal protein synthesis in chicken embryo brain cells induced by AC. RESULTS: The contents of Ca2+ percentage, the concentrations of cytosolic free Ca2+, and the activities of Ca2+/CaM-PK II in the cells were increased significantly as AC was added (P < 0.01). However, the content of Ca(2+)-free CaM and the synthesis of cytoskeletal proteins were markedly decreased (P < 0.01). CONCLUSION: The results suggest that one of the mechanism of AC-induced cytoskeletal injury in vitro might be related to the elevation of intracellular Ca2+, activated CaM and Ca2+/CaM-PK II.

Allyl Compounds↗
PubMed1998

[Purification of recombinant erythropoietin by reversed-phase high performance liquid chromatography (RP-HPLC)].

Recombinant erythropoietin is a glycoprotein which is strongly hydrophobic. We purified recombinant erythropoietin by RP-HPLC. The results showed that 30 nm Spherisorb C4 reversed-phase column and acetonitrile-TFA mobile phase with gradient elution, could readily isolate recombinant erythropoietin from crude samples with high speed and efficiency. Erythropoietin could be eluted at the concentration of about 50% acetonitrile with appropriate sample purity and elution gradient. When RP-HPLC is used as a final step of purification, the purity of sample should be at least 60%. The purity of the product tested by SDS-PAGE was nearly 100%. And the specific activity of the product was about 1.96 x 10(3) IU/g protein.

Chromatography, High Pressure Liquid↗
PubMed1998

[Experimental study of dahuang zhechong pills in the treatment of immunological liver fibrosis in rats].

OBJECTIVE: To study the effect of DHZC on liver fibrosis. METHOD: Immuno-injured fibrosis in rats was induced by bovine serum albumin and DHZC was given during and after the model production respectively. Hepatic collagen contents, pathology of liver and serum hyaluronic acid were measured. Colchicine was used as control. RESULT: It shows that the liver fibrosis rates of the DHZC treated group during and after the model production were 72.7% and 71.2% respectively, while those of the untreated and colchicine group were 92.3%-100%. Compared with the untreated group, there was a remarkable decrease of hepatic collagen contents in the DHZC-treated rats. CONCLUSION: DHZC have thus been proved helpful in reversing liver fibrosis to some extent.

Animals↗
PubMed1998

[Absorbable self-reinforced biomaterials used for fracture fixation implants].

A series of absorbable polymers used for osteosynthesis implants are introduced in this review. To reduce the degradation rate and increase the strength of them, some methods, such as self-reinforced or coating with other polymers, have been presented. Some clinical and animal's experiments have been discussed.

Absorbable Implants↗
PubMed1997

Determinants of longer duration of endotracheal intubation after adult cardiac operations.

BACKGROUND: Poor pulmonary reserve is a risk factor that is used to exclude some patients from major operations. However, the value of routine spirometry in patients undergoing cardiac operations has not been widely evaluated. METHODS: The outcomes of 586 consecutive adult patients undergoing cardiac operations were reviewed retrospectively to assess predictors of longer duration of endotracheal intubation. RESULTS: By univariate analysis, congestive failure (p < 0.001), cardiomegaly (p = 0.002), recent myocardial infarction (p = 0.039), priority of operation (p = 0.005), previous cardiac operation (p < 0.001), and renal insufficiency (p = 0.002) increased the risk of longer endotracheal intubation. Spirometry (forced vital capacity, forced expiratory volume at 1 second, the ratio of forced expiratory volume at 1 second to forced vital capacity) did not correlate with longer endotracheal intubation. Perioperative complications, such as myocardial infarction (p < 0.001), coma, reexploration for bleeding, and reduced cardiac output (p < 0.001 each), correlated with longer duration of intubation. By multiple regression, priority of operation (p = 0.03), congestive failure (p = 0.02), and previous cardiac operation (p = 0.005) among preoperative risks and bleeding, reduced cardiac output, stroke, coma, and MB fraction of creatine kinase released postoperatively (p < 0.001 each) predicted longer duration of endotracheal intubation. CONCLUSIONS: Postoperative cardiac function and the occurrence of complications are more significant than preoperative pulmonary function in determining the duration of endotracheal intubation after cardiac operation. Routine spirometry is probably unnecessary for most adult cardiac patients.

Adult↗
PubMed1997

Surgical treatment for primary esophageal cancer developing after pharyngolaryngectomy for head and neck cancer.

BACKGROUND: Primary esophageal cancer developing after hypopharyngeal or laryngeal cancer is increasing in frequency, but operative treatment of such cases is not well established. The proximity of both cancers could produce interactive influence on surgical procedures and risk factors. There have been few reports focusing on surgical strategy for such cases. METHODS: We retrospectively investigated the most recent series of 18 patients who had previously undergone pharyngolaryngectomy for cancer and subsequently underwent esophagectomy for second primary cancer of the esophagus. At esophagectomy special care was taken to preserve the tracheal vascularity and to select adequate procedures for lymph node dissection and bowel reconstruction. RESULTS: Curative resection as confirmed macroscopically was achieved in all cases except one. Lymph node involvement was found in half of the patients. No major postoperative complication was observed except for partial necrosis of the trachea in two cases that were conservatively treated. No patient died during hospitalization. The 3-year survival rate was 64% overall and 55% in cases with lymph node involvement. CONCLUSIONS: Although increased operative risk was expected in esophagectomy after pharyngolaryngectomy, our operative results were acceptable. Most risk factors were controllable by selecting appropriate operation procedures. In patients with technically resectable cancer, esophagectomy with systematic lymph node dissection is recommended as in ordinary esophageal cancer.

Aged↗
PubMed1997

Factors influencing survival rate in adenoid cystic carcinoma of the salivary glands.

Ninety-one cases of adenoid cystic carcinoma (ACC) of the salivary glands with more than ten years' follow up were studied to investigate factors influencing the survival rate of patients, which vary according to site, histological type, clinical stage and nature of therapy. The data were statistically analysed for survival curves. Log rank tests were employed to assess the statistical significance of various groups. As a result, it may be concluded that tumour site, clinical stage and histological type are the important factors influencing the prognosis. ACC of the palate and parotid, early clinical stage, glandular/tubular histological type, and tumour without nerve involvement had the best prognosis. ACC in the submandibular gland, maxillary antrum and tongue, advanced clinical stage (stage III and IV), solid histological type, and tumour with nerve involvement had a poor prognosis.

Adult↗
PubMed1997

Cholecystokinin activates area postrema neurons in rat brain slices.

Peripheral cholecystokinin (CCK) reduces food intake and triggers the secretion of both oxytocin and corticotropin-releasing hormone. These responses are partially initiated by activation of receptors in the peripheral endings of the vagus nerve. However, in vivo studies showing that after vagotomy systemic CCK induces fos activation of neurons in the area postrema (AP) suggest that circulating CCK may directly influence the activity of neurons in this structure. The present study was therefore designed to investigate the responsiveness of AP neurons to CCK using in vitro extracellular single-unit recording techniques. Bath application of 100 nM CCK for 200 s resulted in excitatory responses in 41% and inhibitory effects in 6% of 143 AP neurons tested. Application of multiple doses of CCK (1-100 nM) to single neurons demonstrated that CCK effects were dose dependent. The firing rate of tested neurons increased by 48 +/- 15% in response to 1 nM, by 89 +/- 22% in response to 10 nM, and by 242 +/- 77% in response to 100 nM CCK. After we blockaded synaptic transmission with a low-Ca2+/high-Mg2+ artificial cerebrospinal fluid, the excitatory effects of CCK remained in all nine neurons tested. The CCK-receptor antagonist L-364,718 had no significant effect on the responses to CCK (P > 0.1, n = 4), whereas, after perfusion of slices with the CCKB-receptor antagonist L-365,260, mean responses to CCK were significantly reduced to 12.6 +/- 4.7% of the control value (P < 0.001, n = 4). These results demonstrate a direct and dose-dependent excitatory action of CCK on AP neurons that is abolished by CCKB-receptor antagonists. These data emphasize the potential role of AP in processing afferent information derived from circulating peptide concentrations that could be involved in the regulation of food intake.

Action Potentials↗
PubMed1997

Differential regulation of 11 beta-hydroxysteroid dehydrogenase type 1 and 2 by nitric oxide in cultured human placental trophoblast and chorionic cell preparation.

Two types of 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) have been identified in different tissues. Type 1 has both oxidase and reductase activities interconverting cortisol and cortisone, whereas type 2 has only oxidase activity converting cortisol to cortisone. It has been proposed that placental 11 beta-HSD controls the passage of maternal glucocorticoids to the fetal circulation. However, little is known about the regulation of 11 beta-HSD in the human placenta and fetal membranes. We cultured human term placental trophoblast and chorionic trophoblast cells to examine effects of nitric oxide donors, sodium nitroprusside (SNP) and S-nitroso-N-acetyl penicillamine (SNAP), on the activity and messenger RNA (mRNA) expression of 11 beta-HSD. At 72 h of culture, placental trophoblast formed syncytial clumps that were cytokeratin positive and displayed mainly type 2 oxidase activity, although some type 1 reductase activity was detectable. Chorion preparations contain greater than 90% trophoblast cells as demonstrated by immunostaining for cytokeratin and less than 5% vimentin positive cells. Type 1 reductase activity predominated in the chorionic trophoblast cells with barely detectable type 1 or type 2 oxidase activity. Both SNP (1-400 microM) and SNAP (1 mM) inhibited placental 11 beta-HSD type 2 oxidase activity but not type 1 reductase activity either in placental or chorionic cells. An inhibitory effect on type 2 oxidase activity was reproduced in part by 8-bromo cGMP, blocked partially by the guanylate cyclase inhibitor LY83583 (1 microM), but not by an ADP-ribosylation inhibitor N, N'-hexamethylene-bis-acetamide (HMBG) (10 mM). SNP also suppressed the expression of type 2 mRNA in cultured placental trophoblast in a dose-dependent manner, and this effect was also blocked by LY83583. We conclude that human placental trophoblast possesses predominantly 11 beta-HSD type 2 oxidase activity, whereas chorionic cells possess mainly type 1 reductase activity under the culture conditions employed. Nitric oxide specifically attenuated 11 beta-HSD type 2 oxidase activity as well as its mRNA expression in the placental trophoblast. The effect was mediated at least partially through the cGMP pathway, although an alternative pathway other than ADP-ribosylation may exist.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1997

Differential expression of 11 beta-hydroxysteroid dehydrogenase types 1 and 2 in human placenta and fetal membranes.

Two isoforms of 11 beta-hydroxysteroid dehydrogenase (11 beta HSD) are present in mammals. 11 beta HSD1 interconverts biologically active cortisol and inactive cortisone, whereas 11 beta HSD2 only converts cortisol to cortisone. Placental 11 beta HSD has been proposed to protect the fetus from high level of maternal glucocorticoids. Although bidirectional activity of 11 beta HSD has been demonstrated in homogenized human placental tissues, the tissue and cellular distribution of 11 beta HSD1 has not been resolved. In this study, the cellular localization of 11 beta HSD1 protein and levels of its messenger ribonucleic acid (mRNA) in human placenta and fetal membranes were determined by immunohistochemistry and Northern blot analysis, respectively. We found that 11 beta HSD1 immunoreactivity was present in the placental extravillous intermediate trophoblasts, chorion trophoblasts, amnion epithelial cells, and stromal cells of the decidua vera. Positive staining was also observed in the endothelium of the blood vessels in both placental villous tissue and umbilical cord. However, in contrast to previous reports of immunoreactive 11 beta HSD2 localization, 11 beta HSD1 immunoreactivity was undetectable in placental syncytiotrophoblast. Using a human 11 beta HSD1 complementary DNA as probe, a 1.5-kilobase mRNA transcript was detected in the chorion, amnion, and placental tissue, with the greatest amount in the chorion. In contrast, the 1.9-kilobase mRNA of 11 beta HSD2 was observed only in the placenta, not in the chorion and amnion. The process of labor had no significant effect on levels of 11 beta HSD1 or 11 beta HSD2 mRNA in the chorion or placenta. We conclude that there is a striking difference in the tissue localization of 11 beta HSD1 and 11 beta HSD2 expression in the late gestation human placenta and fetal membranes, which may discretely determine the accessibility of bioactive glucocorticoid to specific cell types.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1997

[The behaviour and treatment of myoepithelial carcinoma of salivary glands].

Nineteen cases of myoepithelial carcinoma (malignant myoepithelioma) in salivary glands were studied clinicopathologically. The clinical features are as follows: arise most frequently within the parotid glands, followed by the submandibular glands; rapidly enlarging mass with extensive invasion of the surrounding tissues in some cases; low rate of cervical lymph node metastasis but high rate of distant metastasis; very frequent recurrence after surgical excision; and poor prognosis. The carcinoma belongs to the high grade malignant tumor. It must be treated radically. The elective neck dissection is generally unnecessary. It is resistant to radiotherapy. It is possible to get rather good result in limited recurrent tumors by prompt surgery.

Adolescent↗
PubMed1997

[Image analysis of cell nuclear morphology and DNA content in osteosarcoma of the jaws].

The measurement of nuclear morphology and quantitative analysis of nuclear DNA content were made by Interactive Image Analysis System in 47 osteosarcomas of the jaws. The results showed that with a decreased degree of differentiation, the cell nuclei of osteoblastic and chondroblastic osteosarcomas came to be large and irregular, those of fibroblastic osteosarcomas, however, to be small and round. It was revealed that high-grade osteosarcomas had increased amounts of DNA and that the mean of DNA content, proportion of hyperploid cells and tumor ploidy were found to be of important prognostic value.

Cell Nucleus↗
PubMed1997

[Clear cell odontogenic carcinoma].

Histopathologic and immunohistochemical features of 3 cases of clear cell odontogenic carcinoma were studied. The tumors were composed of sheets or islands of clear cells separated by mature collageneous tissue. Basaloid cells were also seen in the tumors. Tumor cells showed positive reactions for epithelial membrane antigen and cytokeratin. More PCNA positive cells were seen in basaloid cells than in clear cells. Metastasis to regional lymph nodes was found in all 3 cases.

Adenocarcinoma, Clear Cell↗