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Biomedical subjects

S Han

Publications and source records attributed to S Han.

At least 181 records · Page 10Linked to original sources
PubMed1999

c-Myc expression is related with cell proliferation and associated with poor clinical outcome in human gastric cancer.

We underwent protein assay for Myc expression in 76 human gastric cancer tissues using immunohistochemistry. Expression of Myc protein was analyzed according to proliferative indices measured by flow cytometry. Levels of Myc protein expression was evaluated by correlating with biologic and clinical parameters. In 36 (47.4%) of 76 primary gastric cancers, overexpression of Myc was observed. We could observe expression of Myc protein in a significant portion of early gastric cancer (42.9%). Expression of Myc protein was demonstrated to be more frequent in poorly differentiated cancer cells (p=0.043). However, expression of Myc protein had little influence over progress or extent of the disease. Expression of Myc protein was significantly correlated with increased proliferative activity (p=0.032) and patients with high levels of Myc expression had poor disease-free survival. In a certain proportion of human gastric cancer, Myc protein may function as a regulator of cancer cell growth and expression of Myc may represent an aggressive phenotype of gastric cancer.

Adult↗
PubMed1999

99mTc-MIBI scan in mammary Pagets disease: a case report.

Technetium-99m methoxyisobutylisonitrile (99mTc-MIBI) uptake is known to be increased in breast cancer because of increased blood flow from angiogenesis and heightened metabolism. We performed a 99mTc-MIBI scan in a patient with mammary Paget's disease. The patient had underlying invasive cancer in the same side of the breast. 99mTc-MIBI scan exhibited a scintigraphic image of the uptake from the invasive cancer lesion located deeply in the breast toward the epidermis. 99mTc-MIBI showed an uptake in the deeply located invasive cancer lesion as well as nipple lesion. Especially, the delayed phase of Tc-MIBI scan demonstrated the tumor site more accurately. In conclusion, 99mTc-MIBI scan could be a useful adjunct to clinical decision making in the management of Paget's disease of the breast.

Breast Neoplasms↗
PubMed1999

Uniform connectedness and classical Gestalt principles of perceptual grouping.

We assessed whether uniform connectedness (UC; Palmer & Rock, 1994) operates prior to effects reflecting classical principles of grouping: proximity and similarity. In Experiments 1 and 2, reaction times to discriminate global letters (H vs. E), made up of small circles, were recorded. The small circles were respectively grouped by proximity, similarity of shapes, and by UC. The discrimination of stimuli grouped by similarity was slower than those grouped by proximity, and it was speeded up by the addition of UC. However, the discrimination of stimuli grouped by proximity was unaffected by connecting the local elements. In Experiment 3, similar results occurred in a task requiring discrimination of the orientation of grouped elements, except that the discrimination of stimuli grouped by UC was faster than that of those grouped by weak proximity. Experiment 4 further showed that subjects could respond to letters composed of discriminably separate local elements as fast as to those without separated local elements. The results suggest that grouping by similarity of shapes is perceived slower than grouping by UC, but grouping by proximity can be as fast and efficient as that by UC.

Adult↗
PubMed1999

Interactions between perceptual organization based on Gestalt laws and those based on hierarchical processing.

Our recent research with compound stimuli (Han, Humphreys, & Chen, 1999a) suggests that grouping between local elements facilitates the perception of global structure, whereas encoding closure in local elements enhances their segmentation. The present study presents further evidence supporting this assertion. Experiment 1 first developed a new paradigm in which grouping between local elements was manipulated. Subjects responded to the orientations of perceptual groups consisting of local arrows or triangles embedded in background crosses. Responses to the orientations of the groups were slowed as a function of the increased contrast of the crosses, indicating that the strength of grouping between local arrows or triangles was gradually weakened by increasing the contrast of the crosses. Using a similar paradigm, Experiments 2 and 3 investigated the role of Gestalt factors in hierarchical analysis. Global arrows or triangles made up of local arrows, or triangles were embedded in background crosses. Subjects responded to global or local stimuli in terms of orientation or closure. Increasing the contrast of the background crosses produced stronger effects on global responses than on local responses and resulted in elimination of the global precedence effect and emerging of a local precedence effect, which was stronger for closure discrimination than for orientation discrimination. These results provide new evidence supporting our previous claim about the role of Gestalt factors in hierarchical analysis.

Adult↗
PubMed1999

D2 autoreceptors are not involved in the down-regulation of the striatal dopamine transporter caused by alpha-methyl-p-tyrosine.

The mechanisms by which the brain dopamine neuronal transporter is regulated by chronic alteration of dopamine transmission are not well understood. It has been shown previously that chronic inhibition of dopamine synthesis decreases dopamine transporter (DAT) density and function. The purpose of the present study was to determine whether these effects involve dopamine D2 receptors. Chronic treatment with alpha-methyl-p-tyrosine decreased binding of [3H]mazindol and dopamine release by d-amphetamine. The down-regulation of the DAT by alpha-methyl-p-tyrosine was not altered by co-treatment with a D2 receptor agonist or antagonist. However, chronic treatment with a D2 agonist, quinpirole, also decreased mazindol binding and amphetamine-induced release of dopamine. The results indicate that chronic inhibition of dopamine synthesis and stimulation of D2 receptors have similar, but independent, effects on DAT binding and function.

Animals↗
PubMed1999

[Methotrexate combined chemotherapy for chemorefractory gestational trophoblastic tumour].

OBJECTIVE: To evaluate the response rate and toxicity of etopside, methotrexate, kengshengmycin, cyclophosphamide and vincristine (EMA/CO) regimen for women with chemorefractory gestational trophoblastic tumour. METHODS: Fifty-one patients with chemorefractory gestational trophoblastic tumour were treated by EMA/CO regimen. Operative excision and (or) selective arterial infusion as adjuncts to chemotherapy were performed in a selected subset of patients. The response and toxicity were assessed after treatment. RESULTS: Fifty-one patients received 352 cycles of the study regimen. The median number of courses for each patient was 6.9. Thirty-three cases (64.7%) achieved a complete remission while 14 patients (27.5%) had a partial remission, 4 cases showed nonresponse. Two (6.7%) of 30 complete responders developed recurrences. The main complications for EMA/CO chemotherapy were myelosuppression and gastrointestinal symptoms. CONCLUSION: The EMA/CO regimen is an effective treatment for chemorefractory gestational trophoblastic tumour, and the chemotherapeutic results can be further improved while combined with arterial infusion chemotherapy and surgery in the selected patients.

Adult↗
PubMed1999

[A study on the symptoms and diagnostic criteria of irritable bowel syndrome in Chinese].

OBJECTIVE: To explore the related symptoms of irritable bowel syndrome (IBS) and its diagnostic criteria in Chinese. METHODS: Symptomatic IBS was diagnosed using Manning criteria in a screening of 2486 subjects in Beijing. A questionnaire study was carried out randomly by clustering samples of residential groups according to a stratified design of city, suburban and rural areas. The sample size of each area studied was in proportion with the population of the area. Symptoms were recorded in detail by trained doctors and medical students and the results underwent computer analysis by comparing their percentages in an IBS (n = 215) group with those in a non-IBS (n = 2271) group. Single factor analysis was done by using Chi square test, those factors of significance were further analyzed by logistic analysis of multifactor. RESULTS: In the single factor analysis, as much as 22 symptoms regarding the whole GI tract and urinary bladder were considered to be significantly related to IBS. After multifactor- analysis, those symptoms of colonic origin remain to be most significant; they were: (1) abdominal pain (> 6 times/a), (2) abdominal pain accompanied by altered bowel habits (both diarrhea and constipation), (3) pain released after defecation, (4) mucus in stool. CONCLUSION: (1) Abdominal pain accompanied by altered bowel habit and pain relieved after defecation are the essential symptoms of IBS. Manning criteria modified by adding constipation with a positive predictive value of 80%, is most suitable in the epidemiologic study as well as in clinical screening of IBS in Chinese; Rome criteria with a positive predictive value of 75% is more reliable in research work and clinical trial. (2) Exclusion of organic disease is important in the diagnosis. (3) There is an overlapping of symptoms between IBS and functional dyspepsia, but those whose colonic symptoms predominate should be diagnosed as IBS, and vise versa. (4) IBS may present extraintestinal symptoms, such as symptoms of the urinary bladder, etc.

Abdominal Pain↗
PubMed1999

[The effect of memory T lymphocytes on IgE production by B lymphocytes in patients with bronchial asthma].

OBJECTIVE: To study the role of CD(4)(+) CD(45)RO(+) T lymphocytes in the pathogenesis of bronchial asthma. METHODS: CD(4)(+) CD(45)RO(+) T lymphocyte subsets were isolated from peripheral blood of patients with bronchial asthma and healthy donors. Then they were cultured with self-B lymphocytes and designated as pokeweed mitogen (PWM)-stimulated and non-stimulated group. Secreted IgE was measured in the supernatant. RESULTS: CD(4)(+) CD(45)RO(+) T lymphocytes had a positive role on IgE production by B lymphocytes from patients of bronchial asthma in non-stimulated group, but the positive role did not exit in the presence of PWM. The effect of activated and non-activated CD(4)(+) CD(45)RO(+) T lymphocytes from patients with bronchial asthma on the secretion of IgE by B lymphocytes were further investigated. CONCLUSION: The function of activated CD(4)(+) CD(45)RO(+) T lymphocytes returned to normal level. It is suggested that CD(4)(+) CD(45)RO(+) T lymphocytes have adverse effects on IgE production in patients with bronchial asthma; which may be related to the pathogenesis of asthma.

Adolescent↗
PubMed1999

[Adrenal cortical carcinoma].

OBJECTIVE: To study the diagnosis and treatment of adrenal cortical carcinoma. METHODS: Fifteen cases of adrenal cortical carcinoma (8 functional and 7 nonfunctional) were treated surgically during the period of 1978 - 1998. They were confirmed operatively and pathologically. RESULTS: The functional carcinoma usually showed typical clinical features such as Cushing's syndrome, primary aldosteronism, and adrenogenital syndrome. The nonfunctional had extra-adrenal symptoms such as acute abdominal pain and hypertension. A definite diagnosis can be made by the measurements of urine 17-ketosteroid, 17-hydrosteroid, cortisol, aldosterone, CT, and B-ultrasonography. CONCLUSIONS: Surgical removal of the tumor is the only effective treatment. Early diagnosis of adrenal cortical carcinoma is very difficult, especially in the non-functional.

Adolescent↗
PubMed1999

[An electrophysiological study of the kainic acid toxicity on cochleas].

OBJECTIVE: The purpose of this study was to investigate the kainic acid (KA) toxicity on cochleas. METHOD: One microliter KA in the concentration of 60 mM was applied to the round window membrane of guinea pig. The compound action potential (CAP), cochlear microphonic potential (CM) and distortion product otoacoustic emissions (DPOAE) were measured 12 hours after KA was administrated. RESULT: CAP was suppressed significantly or abolished after the drug administration, however, the CM and DPOAE almost presented no change. CONCLUSION: The targets of KA toxicity are the primary auditory afferent endings.

Action Potentials↗
PubMed1999

[Prediction the octane number of gasoline by near infrared spectra analysis].

The feasibility of predicting the octane number by the near infrared spectra analysis technique in the quantitative analysis was investigated. 12 calibration gasoline samples and 4 prediction samples were collected and their absorption spectra were measured with a high precision model Lambda 19 scanning spectrophotometer. Based on the multivariate statistic model, stagewise regression and partial least squares were selected. A model of the correlation behavior between the spectra and octane number was established and calibrated, and then the prediction of octane number is made. The prediction error is +/-1.0 octane number in the best analysis results.

Gasoline↗
PubMed1998

An analysis of two tandem promoters of the Drosophila purple gene.

We have analyzed two tandem promoters, separated by only about 400 bp, of the purple (pr) gene of Drosophila melanogaster, by fusing them to the firefly luciferase reporter gene and employing a transient expression assay with Drosophila S2 cells. Both the distal promoter and the proximal promoter were found to function in S2 cells and an about 700 bp long region (-270 to +421), containing both promoters, was sufficient to effect maximal promoter activity. When the two promoters were analyzed separately, the distal promoter was found to be much stronger in its function than the proximal promoter. At least three different kinds of cis elements near the transcription start site appear to play crucial roles in driving constitutive expression from the distal promoter. On the other hand, only a single cis element, which may play a role in tissue-specific expression, appears to be important for the activity of the proximal promoter in S2 cells. We propose that the clustering of important cis elements near the transcription start sites may be responsible for the selective regulation of the two tandem promoters.

Animals↗
PubMed1998

Molecular basis for the stabilization and inhibition of 2, 3-dihydroxybiphenyl 1,2-dioxygenase by t-butanol.

The steady-state cleavage of catechols by 2,3-dihydroxybiphenyl 1, 2-dioxygenase (DHBD), the extradiol dioxygenase of the biphenyl biodegradation pathway, was investigated using a highly active, anaerobically purified preparation of enzyme. The kinetic data obtained using 2,3-dihydroxybiphenyl (DHB) fit a compulsory order ternary complex mechanism in which substrate inhibition occurs. The Km for dioxygen was 1280 +/- 70 microM, which is at least 2 orders of magnitude higher than that reported for catechol 2,3-dioxygenases. Km and Kd for DHB were 22 +/- 2 and 8 +/- 1 microM, respectively. DHBD was subject to reversible substrate inhibition and mechanism-based inactivation. In air-saturated buffer, the partition ratios of catecholic substrates substituted at C-3 were inversely related to their apparent specificity constants. Small organic molecules that stabilized DHBD most effectively also inhibited the cleavage reaction most strongly. The steady-state kinetic data and crystallographic results suggest that the stabilization and inhibition are due to specific interactions between the organic molecule and the active site of the enzyme. t-Butanol stabilized the enzyme and inhibited the cleavage of DHB in a mixed fashion, consistent with the distinct binding sites occupied by t-butanol in the crystal structures of the substrate-free form of the enzyme and the enzyme-DHB complex. In contrast, crystal structures of complexes with catechol and 3-methylcatechol revealed relationships between the binding of these smaller substrates and t-butanol that are consistent with the observed competitive inhibition.

Biodegradation, Environmental↗
PubMed1998

Lymphocyte activation: the coming of the protein tyrosine phosphatases.

The molecular mechanisms of signal transduction have been at the focus of intense scientific research world-wide. As a result, our understanding of protein tyrosine kinase-mediated signaling has advanced at an unprecedented pace during the past decade. In contrast, the study of protein tyrosine phosphatases is in its infancy, but is currently gathering momentum and is predicted to become a "hot topic" in the field within the next few years. This review summarizes the current state-of-the art in our understanding of the structure, regulation and role of protein tyrosine phosphatases in lymphocyte activation.

Animals↗
PubMed1998

Electroacupuncture: mechanisms and clinical application.

Acupuncture is an ancient Chinese method to treat diseases and relieve pain. We have conducted a series of studies to examine the mechanisms of this ancient method for pain relief. This article reviews some of our major findings. Our studies showed that acupuncture produces analgesic effect and that electroacupuncture (EA) is more effective than manual acupuncture. Furthermore, electrical stimulation via skin patch electrodes is as effective as EA. The induction and recovering profiles of acupuncture analgesia suggest the involvement of humoral factors. This notion was supported by cross-perfusion experiments in which acupuncture-induced analgesic effect was transferred from the donor rabbit to the recipient rabbit when the cerebrospinal fluid (CSF) was transferred. The prevention of EA-induced analgesia by naloxone and by antiserum against endorphins suggests that endorphins are involved. More recent work demonstrated the release of endorphins into CSF following EA. In addition, low frequency (2 Hz) and high frequency (100 Hz) of EA selectively induces the release of enkephalins and dynorphins in both experimental animals and humans. Clinical studies suggesting its effectiveness for the treatment of various types of pain, depression, anxiety, spinally induced muscle spasm, stroke, gastrointestinal disorders, and drug addiction were also discussed.

Acupuncture Analgesia↗
PubMed1998

Activation and stabilization of chymotrypsin in microdomains of poly(ethylenimine) derivatives. A model of in vivo environment.

Both activity and stability of alpha-Chymotrypsin (ChT) are substantially enhanced in the microdomains of laurylated or benzylated derivatives of poly(ethylenimine). EPR data revealed that the enhancement in activity of ChT is due to increase in the polarity of the microenvironment of Ser-195 caused by complexation of ChT to the polymer derivatives.

Benzyl Compounds↗
PubMed1998

Characterization of Mas-7-induced pore formation in SK-N-BE(2)C human neuroblastoma cells.

Mastoparan, a peptide toxin from wasp venome, mimics receptors by stimulating the GTPase activity of guanine nucleotide binding proteins and the G-protein-coupled phospholipase C (PLC). By using Mas-7, the active analog of mastoparan, we showed that it makes pores in the plasma membrane. Treatment with Mas-7 but not Mas-17, the inactive analog, produced a concentration-dependent rise in intracellular Ca2+ concentration ([Ca2+]i) and facilitated the uptake of ethidium bromide (EtBr) (314 Da) to a sustained level during the stimulation. In addition, Mas-7 triggered the influx of lucifer yellow (457 Da), while it did not induce the influx of fura-2 (831 Da) and Evans blue (961 Da). However, the Mas-7-induced permeability was selectively prevented by the addition of La3+, Ni2+, and Co2+, but not Cd2+. This blocking activity was concentration-dependent. While the stimulatory effect of Mas-7 on PLC activity was dependent on extracellular Ca2+, the pore forming activity of Mas-7 was not effected by removal of extracellular Ca2+. These results, therefore, suggest that the mastoparan's action in pore formation is independent from its action in PLC stimulation and is negatively effected by inorganic cations.

Calcium↗