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Biomedical subjects

K Fang

Publications and source records attributed to K Fang.

At least 37 records · Page 2Linked to original sources
PubMed1999

[Improvements on radical neck dissection].

OBJECTIVE: To improve the surgery of radical neck dissection for a better curative effect. METHOD: Some improvements on incision, path to exploration and manipulation of operation were made in 65 patients with head and neck tumors while radical neck dissection were done. RESULT: The average surgical time was 110 minutes and the average amount of bleeding was 120 ml in the patients when radical neck dissection had been completed. The complications decreased to 1.54%. The surviual rates of 2 and 3 years are 86.2% (56/65) and 81.6 (31/38) respectively. CONCLUSION: With these improvements on radical neck dissection, the curative effect in the near future is improved.

Adolescent↗
PubMed1998

Reductive assays for S-nitrosothiols: implications for measurements in biological systems.

Bioactive SNOs are found in many tissues. We speculated SNOs might be misidentified in conventional assays which reduce NO-3 to NO. S-Nitrosothiols were exposed to saturated VCl3 in HCl, 1% KI in acetic acid, photolysis, or CuCl and CSH in He; NO was measured by chemiluminescence. S-Nitrosothiols were readily detected in VCl3 but not in KI. Reduction in CuCl/cysteine was linear (r2 = 1.0, n = 6), sensitive to 10 pmol, and eliminated by HgCl2; it did not detect NO-2, NO-3, or 3-nitrotyrosine. S-Nitrosothiols represented approximately 2.9% of NOx assayed by VCl3 in human serum, of which <5% were low-mass species. In summary, (i) conventional assays may misidentify NO-3, but not NO-2, as SNOs; and (ii) chemiluminescence/reduction systems may be sensitive and specific as SNO assays. We suggest that assay of the SNO fraction in biological NOx may be more relevant and feasible than is now appreciated.

Chromatography, High Pressure Liquid↗
PubMed1998

[Spectroscopic ellipsometry characteristics and the optical properties of liquid crystalline copolyesters].

The optical properties of two thermotropic liquid crystalline copolyesters were characterized by spectroscopic ellipsometry and UV-visible spectroscopy. The differences in the refractive index variation and chromatic dispersion have been revealed and discussed in terms of differences in the vibrating transition of excited electrons and the molecular structures of the polymers.

English Abstract↗
PubMed1998

A toxin conjugate containing transforming growth factor-alpha and ricin A specifically inhibits growth of A431 human epidermoid cancer cells.

The inhibitory effect of human epidermoid cancer cells A431 caused by conjugate toxin containing transforming growth factor (TGF-alpha) and ricin A was studied. TGF-alpha is a protein with 50 amino acids that specifically binds and stimulates phosphorylation of cell surface epidermal growth factor receptor (EGFR) and, subsequently, triggers cell proliferation. TGF-alpha as a ligand for EGFR is internalized upon binding and decomposed within lysosome. Lectin ricin is contained in the castor bean plant. The lectin consists of two subunits, ricin A and B. Toxic ricin A binds to ribosome and inhibits protein synthesis of target cells. In view of the abundance of EGFR in human cancer cells, the receptor-mediated endocytosis with the conjugate toxin composed of TGF-alpha and ricin A was synthesized, purified and tested for growth inhibition in both normal and tumor cells. The cytotoxicity of the conjugate was studied within the range of 10(-12) and 10(-8) M and IC50 was found to be 10(-10) M for human A431 epidermoid cells that over-express EGFR. Compared to A431 cells, the brain metastatic variant of human Non-Small Cell Lung Cancer (NSCLC) H226Br squamous cells showed a reduced inhibitory effect. On the other hand, no inhibitory effect was found with other NSCLC cells studied and normal human lung cells because of the fewer available EGF binding sites on the surface of the cells. These results indicated that the amount of the available EGFR contributes to the cytotoxic effect on human cancer cells, thereby demonstrating involvement of the receptor-mediated endocytosis of the conjugate. The result from 12labeled EGF-mediated competition assay further demonstrated the specific inhibition activity conferred by TGF-alpha and ricin A conjugation. Due to poor recovery of the chemical conjugation, modification in the form of a recombinant toxin is needed for further in-depth studies.

Affinity Labels↗
PubMed1997

Structure-binding relation of philanthotoxins from nicotinic acetylcholine receptor binding assay.

Philanthotoxins are noncompetitive inhibitors of the nicotinic acetylcholine receptor and the various glutamate receptors. Analogues carrying photoaffinity labels, fluorine atoms for solid-state NMR studies of ligand/receptor interaction, and large head groups such as porphyrins and planar bulky aromatic rings (BIG analogues) for clarifying mode of entry and orientation of analogues in receptors have been synthesized, assayed against the nicotinic acetylcholine receptor, and brief comments are given for the assay results.

Amino Acids↗
PubMed1997

[Detecting HPV DNA in tissue of epidermal neoplasms].

Fifty-eight cases (mean age 56.1 +/- 17.1 years) of cutaneous squamous cell carcinoma were studied, including 17 cases of Bowen's disease, 5 cases of Queyrat erythroplasia, 16 cases of Bowenoid papulosis and 20 cases of invasive cutaneous squamous cell carcinoma. All cases were confirmed by pathological findings. HPV6, 11, 16, 18 DNA were detected by multiple pair primers polymerase chain reaction in paraffin-embedded tissues. The results showed that 2(2/17) cases of Bowen's disease, 1 case of Queyrat erythroplasia and 9(9/16) cases of Bowenoid papulosis were positive for HPV16 DNA and that 20 cases of invasive cutaneous sqamous cell carcinoma were negative for HPV16 DNA. HPV16 is closely associated with Bowenoid papulosis and HPV16 might be a factor of multistep carcinogenesis in rare cases of Bowen's disease and Queyrat erythroplasia.

Adult↗
PubMed1996

Kinesin movement on glutaraldehyde-fixed microtubules.

Glutaraldehyde-cross-linked microtubules were investigated as substrates for kinesin motility. Microtubules, formed in vitro from chicken brain tubulin, were stabilized with Taxol and chemically fixed with glutaraldehyde. The degree of tubulin monomer cross-linking as a function of time and glutaraldehyde concentration was characterized using polyacrylamide gel electrophoresis. Atomic force microscopy of fixed microtubules indicated that the cross-linking is sufficient to stabilize the gross structure of the microtubules against air drying or a distilled water challenge. Kinesin movement on immobilized, fixed microtubules was determined using a kinesin-coated bead motility assay observed with differential interference contrast microscopy. Within measurement error, kinesin bead movement velocities were independent of the degree of microtubule cross-linking. Binding affinity, however, decreased with increased cross-linking. Although air- and water-challenged microtubules did not support kinesin motility, a dilute suspension of glutaraldehyde-fixed microtubules in buffer supported kinesin motility for at least 2 days without any substantial degradation of activity. Fixed microtubules may be useful for several applications, including affinity purification of microtubule-associated proteins and motility measurements under extreme conditions of temperature and other variables.

Animals↗
PubMed1996

An enhanced and sensitive autocrine stimulation by transforming growth factor-alpha is acquired in the brain metastatic variant of a human non-small-cell lung cancer cell line.

Transforming growth factor-alpha (TGF-alpha)-mediated autocrine regulation in human non-small-cell lung cancer (NSCLC) cells NCI-H226 and its brain metastatic variant H226Br were compared. An enhanced TGF-alpha-induced dose-dependent mitogenic responsiveness in H226Br cells was observed. Neutralising antibody that binds TGF-alpha inhibits H226Br cell growth more effectively than NCI-H226 cell growth. Binding assay with 125I-labelled epidermal growth factor (EGF) revealed that H226Br has two types of EGF receptors (EGFRs), whereas the parental cell line, NCI-H226, has only one. H226Br cells contain twice as many EGFRs as H226 cells, as proved by Scatchard analysis and immune kinase assay. Northern analysis indicated that there is more EGFR transcript in H226Br than in NCI-H226, indicating a transcriptional EGFR gene elevation during metastasis progression. The level of accumulated immunoactive TGF-alpha is lower in the conditioned medium of H226Br than in that of NCI-H226. demonstrating down-regulation of TGF-alpha transcript. The accumulated data suggest an elevated and sensitive autocrine modulation by TGF-alpha and EGFR in immortalising the brain metastatic variant cells that were derived from a human NSCLC squamous cell line.

Animals↗
PubMed1996

Starling resistor effects on pulmonary artery occlusion pressure in endotoxin shock provide inaccuracies in left ventricular compliance assessments.

OBJECTIVES: Assessment of left ventricular preload and left ventricular compliance changes in septic shock using pulmonary artery occlusion pressure (PAOP) presumes that this pressure accurately reflects left heart filling pressure. We tested the hypothesis that Starling resistor forces render PAOP inaccurate as an index of left heart filling pressure, resulting in misleading assessments of left ventricular compliance changes. DESIGN: Prospective, randomized, controlled study. SETTING: Large-animal research laboratory at a university. SUBJECTS: Fourteen anesthetized domestic pigs weighing 20 to 25 kg. INTERVENTIONS: Pulmonary artery flotation catheters and systemic arterial catheters were placed via right cervical vessels. The left atrium was directly catheterized for left atrial pressure measurements. Left ventricular end-diastolic diameter was measured using sonomicrometry. Other measured or calculated variables were mean arterial pressure, mean pulmonary arterial pressure, PAOP, pulmonary capillary pressure, and pulmonary arterial and venous resistances. Pigs received endotoxin (0.5 mg/kg i.v. over 30 mins), or an equivalent volume of saline. At t = 60 mins, pigs were resuscitated with lactated Ringer's solution (40 mL/kg over 30 mins). Measurements were taken before and after endotoxin administration, and immediately and 30 mins after lactated Ringer's solution administration. Data were analyzed by two-way analysis of variance (p < or = .05). MEASUREMENTS AND MAIN RESULTS: PAOP, mean pulmonary arterial pressure, and pulmonary capillary pressure increased after endotoxin infusion, while left atrial pressure and left ventricular end-diastolic diameter decreased. Left atrial pressure and left ventricular end-diastolic diameter returned to baseline immediately after lactated Ringer's solution administration, while PAOP remained increased. Pulmonary arterial resistance and pulmonary venous resistance increased after endotoxin administration, with pulmonary venous resistance showing the greater percent increase. Pulmonary venous resistance decreased transiently immediately after lactated Ringer's solution administration. These changes were not observed in the control group. Accordingly, comparisons of PAOP vs. left ventricular end-diastolic diameter, and left atrial pressure vs. left ventricular end-diastolic diameter yielded divergent results. CONCLUSIONS: The dissociation between PAOP and left atrial pressure, while left ventricular and -diastolic diameter (preload volume) decreased, and changes in pulmonary venous resistance, are strong evidence for Starling resistor forces (venocompression) rather than active venoconstriction. These data indicate that PAOP overestimates left atrial pressure during endotoxin shock, making it an inaccurate index of left ventricular preload. This overestimation can cause misleading assessments of left ventricular compliance.

Animals↗
PubMed1996

[Repair of bilateral cleft lip with unilateral composite lip flap: report 19 patients].

To repair bilateral cleft lip seems to be more difficult than that of unilateral one. In order to correct insufficiency of fore-lip, we have applied the composite lip flap of the thicker side for bilateral cleft lip in 19 patients. Overall results were satisfactory. There was no peculiar appearance indicating that fore-lip is too long or tension in the postoperative follow up from six months to four and half years. In this article, the methods of rotating repair were described in detail. The advantage and key points of the teehnique were discussed. So it may be regarded as one of the ideal measures for repairing bilateral cleft lip.

Child, Preschool↗
PubMed1996

[Differentiation of condylomata acuminata from pseudocondyloma by using multiple primer pairs polymerase chain reaction].

Condylomata acuminata were differentiated from pseudocondyloma by using multiple primer pairs polymerase chain reaction (PCR) technique. The paraffin-embedded tissues of 95 cases of condylomata acuminata and 33 cases of pseudocondyloma were detected for HPV DNA. Results show that HPV 6/11 DNA are found in 86/95 (90.5%) cases of condylomata acuminata, and no HPV DNA is detected in 33 cases of pseudocondyloma. The results suggest that pseudocondyloma is not associated with HPV. Multiple primer pairs PCR technique is a preferable method for differentiating condylomata acuminata from pseudocondyloma.

Adolescent↗
PubMed1995

Insulin-like growth factor-I is an autocrine regulator for the brain metastatic variant of a human non-small cell lung cell line.

Insulin-like growth factor (IGF-I) is associated with autocrine and paracrine stimulation for cell growth and development of brain tumor cells. The function of IGF-I in the brain metastatic variant of human lung cancer cells is investigated. The cells used here were derived in vivo with intracarotid injection of human non-small cell lung carcinoma NCI-H226. The tumor was developed as a cultured cell line, H226Br. Unlike the parental cells, H226Br was tumorigenic in nu/nu nude mice. Reverse transcriptase-polymerase chain reaction showed that IGF-I transcript of H226Br is increased compared to that of parental cells. The amount of IGF-I secreted in cultured medium of H226Br is higher than that of cultured parental cells. The IGF-I receptor-specific antibody, alpha IR3, inhibits H226Br growth in serum-free culture. The results established that IGF-I is an autocrine growth regulator for human non-small cell lung cancer cells that progressed to brain.

Animals↗
PubMed1995

Selective adhesion of functional microtubules to patterned silane surfaces.

We show that microtubule polymers can be immobilized selectively on lithographically patterned silane surfaces while retaining their native properties. Silane films were chemisorbed on polished silicon wafers or glass coverslips and patterned using a deep UV lithographic process developed at the Naval Research Laboratory. Hydrocarbon and fluorocarbon alkyl silanes, as well as amino and thiol terminal alkyl silanes, were investigated as substrates for microtubule adhesion with retention of biological activity. Microtubules were found to adhere strongly to amine terminal silanes while retaining the ability to act as substrates for the molecular motor protein kinesin. Aminosilane patterns with linewidths varying from 1 to 50 microns were produced lithographically and used to produce patterns of selectively adhered microtubules. Microtubules were partially aligned on the patterned lines by performing the immobilization in a fluid flow field. Patterns were imaged with atomic force microscopy and differential interference contrast microscopy. Motility assays were carried out using kinesin-coated beads and observed with differential interference contrast microscopy. Kinesin bead movement on the patterned microtubules was comparable to movement on microtubule control surfaces.

Animals↗
PubMed1995

Differential down-regulation of epidermal growth factor receptors expressed in the metastatic variants of human lung cancer adenocarcinoma cell line DMS4C.

The metastatic variants of human lung adenocarcinoma cell line DMS4C were established by selection in vivo. Lung, brain, spleen and liver metastatic tumors derived from intracarotid inoculation of athymic BALB/c mice were collected, and their corresponding variant cell lines established. The epidermal growth factor (EGF) receptor expression of the parental cell line as well as the metastatic variant cell lines were investigated. 125I-labeled EGF binding assays showed that there were two types of EGF receptors in both parental and metastatic variants. Compared to DMS4C, the EGF binding capacities were found to be down-regulated by 70, 79, 85 and 89% for lung, spleen, liver and brain variant, respectively. The dissociation constants of spleen, liver and brain EGF receptors were distinct from that of the parental cell line. The EGF receptor autophosphorylation activity of lung variant was shown to be down-regulated as shown by immune complex kinase assay that corresponded to EGF receptor numbers whereas kinase activities of the liver, spleen and brain variants EGF receptors were completely abolished. However, the 170 kilodalton EGF receptor was shown to be unaltered during metastasis. The results indicated that, during metastasis progression, the proliferation of adenocarcinoma cells may have adopted a different growth regulation that is independent of EGF receptor kinase-modulated autocrine pathway. The result also implies that other oncogene may emerge as the major growth regulator for distant metastasis of adenocarcinoma cancer cells. This work provides a model for understanding tumor metastasis progression of human lung cancer.

Adenocarcinoma↗
PubMed1992

Autocrine growth stimulation by transforming growth factor-alpha in human non-small cell lung cancer.

We studied the biological response to and production of transforming growth factor-alpha (TGF-alpha) by the non-small cell lung carcinoma (NSCLC) clonal cell lines H226b, H322a, H460a, H596b. Each of these cell lines expressed epidermal growth factor receptor (EGFR) as determined by [125I]EGF competitive binding and Scatchard analysis and by phosphorylation. The receptors were functionally active as determined in immune complex kinase assays. H322a, H226b, H460a, and H596b cells showed stimulated [3H]thymidine (Thd) uptake in response to TGF-alpha. Exogenously added TGF-alpha increased colony formation in soft agar for three of the cell lines in media containing serum. All cell lines expressed TGF-alpha detected by immunohistochemistry and TGF-alpha mRNA, although to differing degrees. Cell lysates and spent media competed for EGFR binding with EGF, thus demonstrating production of TGF-alpha-like activity. The anti-TGF-alpha monoclonal antibody AB-3 inhibited the uptake of [3H]Thd by proliferating H322a and H226b cells but not H460a and H596b cells. No inhibition occurred with MOPC21 antibody and inhibition was completely reversed by addition of TGF-alpha to the culture. Suramin inhibited cell proliferation and [3H]Thd uptake by all cell lines. Inhibition of H460a and H596b cells was reversed with exogenous TGF-alpha but not PDGF. Our data suggests that TGF-alpha is a mediator of autocrine growth stimulation for NSCLC cells, and that for some NSCLC cells cytoplasmic binding of receptor and ligand is the primary mechanism for autocrine growth stimulation.

Animals↗
PubMed1992

Determination of plicamycin in plasma by radioimmunoassay.

This article describes a method for the determination of plicamycin in plasma by radioimmunoassay. The anti-plicamycin antibody was produced against a plicamycin-bovine serum albumin conjugate prepared by using diazotized p-aminobenzoic acid as a cross-linker. The radiolabeled ligand, 125I-plicamycin, was prepared by the chloramine-T method. The linear plicamycin concentration range was 7-400 ng/ml. The coefficients of variation for intra- and interday variabilities were 7.5 and 15%, respectively. No interference was observed from either the structurally related chromomycin A or concomitantly used drugs hydroxyurea or allopurinol. With this method of testing, plicamycin levels in plasma could be determined in patients receiving small (0.85-1.0 mg/m2) therapeutic plicamycin doses. Preliminary pharmacokinetic data in humans indicate that the plasma drug disappearance curve was biphasic with a mean elimination half-life of 10.6 +/- 1.7 h, total clearance rate of 11.1 +/- 0.4 ml/min/m2, and area under the plasma drug concentration-time curve of 1,289-1,546 ng-h/ml. This assay method is clinically useful for pharmacokinetic studies of plicamycin and may be helpful in the design of rational therapeutic drug trials.

Antibody Specificity↗