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Biomedical subjects

W Su

Publications and source records attributed to W Su.

At least 55 records · Page 3Linked to original sources
PubMed2000

Detection of antitumor and antimicrobial activities in marine organism associated actinomycetes isolated from the Taiwan Strait, China.

The purpose of this work was to screen the actinomycetes having antitumor or antimicrobial activity, which were isolated from the surface, epidermis and intestines of sea plants and animals collected from the Taiwan Strait, China. Antitumor activity was studied by the MTT assay and DNA target activity was studied by the biochemical induction assay while antimicrobial activity was determined by observing bacterial and fungal growth inhibition. 20. 6% of marine actinomycete cultures displayed cytotoxic activity on P388 cells at dilutions at and below 1:320 and 18.6% on KB cells. 2. 96% of marine actinomycete cultures displayed inducing activity. Among all marine actinomycetes isolated, the genus Micromonospora has the highest positive rate of inducing activity. However, most antimicrobial activity was found in the genus Streptomyces. These results indicate that marine organism associated actinomycetes could be a promising source for antitumor and antimicrobial bioactive agents.

Actinomycetales↗
PubMed2000

Carcinogenic metals induce hypoxia-inducible factor-stimulated transcription by reactive oxygen species-independent mechanism.

Nickel (Ni2+) and cobalt (Co2+) mimic hypoxia and were used as a tool to study the role of oxygen sensing and signaling cascades in the regulation of hypoxia-inducible gene expression. These metals can produce oxidative stress; therefore, it was conceivable that reactive oxygen species (ROS) may trigger signaling pathways resulting in the activation of the hypoxia-inducible factor (HIF)-1 transcription factor and up-regulation of hypoxia-related genes. We found that the exposure of A549 cells to Co2+ or Ni2+ produced oxidative stress, and although Co2+ was a more potent producer of ROS than Ni2+, both metals equally increased the expression of Cap43, a hypoxia-regulated gene. The coadministration of hydrogen peroxide with metals induced more ROS; however, this did not further increase the expression of Cap43 mRNA. The free radical scavenger 2-mercaptoethanol completely suppressed ROS generation by CoCl2 and NiCl2 but did not diminish the induced Cap43 gene expression. The activity of the HIF-1 transcription factor as assessed in transient transfection assays was stimulated by Ni2+, hypoxia, and desferrioxamine, but this activation was not diminished when oxidative stress was attenuated nor was HIF-dependent transcription enhanced by hydrogen peroxide. We conclude that ROS are produced during the exposure of cells to metals that mimic hypoxia, but the formation of ROS was not involved in the activation of HIF-1-dependent genes.

Carcinogens↗
PubMed2000

micro-Terephthalato-bis[bis(1,10-phenanthroline)copper(I)] diperchlorate.

The title compound, [Cu(2)(C(8)H(4)O(4))(C(12)H(8)N(2))(4)](ClO(4))(2), was prepared from the hydrothermal reaction of CuCl(2), 1,4-dicyanobenzene, 1,10-phenanthroline and water at 443 K. The compound is a dimer in which the cation lies about an inversion center. The terephthalate moiety acts as a bridging ligand and the phenanthrolines as terminal ligands. The unique Cu atom is coordinated by two O and four N atoms in a distorted octahedral geometry, with Cu-O distances of 1.955 (2) and 2.815 (2) A, and Cu-N distances of 2.008 (2) to 2.216 (2) A.

Journal Article↗
PubMed2000

Bis(N,N-diethyl-1,1-diselenocarbamato-Se)selenium, [(Se(2)CNEt(2))(2)Se].

The polyseleno title compound, bis(N,N-diethylselenocarbamoyl) triselenide, [(Se(2)CNEt(2))(2)Se] or C(10)H(20)N(2)Se(5), is obtained from the disproportion of sodium N,N-diethyl-1,1-diselenocarbamate. An Se atom connects two N,N-diethyl-1,1-diselenocarbamate groups with Se-Se distances in the range 2.4500 (11)-2.8601 (12) A

Journal Article↗
PubMed2000

Assembly of silver(I) polymers with helical and lamellar structures

The new versatile multidentate nonchelating ligand 1,2-bis[(2-pyr-imidinyl)-sulfanylmethyl]benzene (bpsb) was designed and prepared for supramolecular syntheses. Self-assembly between silver nitrate and the bpsb ligand resulted in the polymer [Ag4(bpsb)2-(NO3)4]n (1) with a single-stranded helical chain structure. Each bpsb ligand in 1 acts as a tetradentate ligand, in which two sulfur atoms and two nitrogen atoms from different pyrimidine groups coordinate to four Ag atoms in four different directions. The nitrate anions serve as a template for the formation of the helix and are either embedded in the interior of the helix or located in the flank of the helix. Self-assembly between silver perchlorate and the bpsb ligand under the same conditions gave rise to the polymer [Ag2(bpsb)3(ClO4)2]n (2) comprising a two-dimensional lamellar network containing crownlike cavities. The silver atoms in two adjacent layers are arranged staggered in 2. The two-dimensional lamellar network comprising isolated cavities of [Ag6(bpsb)6] is very different from that of usual honeycomb structures.

Journal Article↗
PubMed2000

Polymer-supported BINOL ligand for the titanium-catalyzed diethylzinc addition to aldehydes: A remarkable positive influence of the support on the enantioselectivity of the catalyst

A new polymer-supported BINOL (1,1'-Bi-2-naphthol) was synthesized by coupling of aminomethyl polystyrene resin and (S)-2, 2'-dihydroxy-1,1'-binaphthyl-3,3'-dicarboxylic acid. This new ligand was found to be more enantioselective for the asymmetric addition of diethylzinc to aldehydes than its "free" analog [Ti(BINOL)(i)PrO(2)]. A range of 57-99% ee's as well as 78-97% yields was obtained, and the electronic properties of the enantioselectivity were also observed.

Journal Article↗
PubMed2000

Treatment of pseudotumors with nonsteroidal antiinflammatory drugs.

Large inflammatory pseudotumors (IPT) traditionally are managed with extensive surgical resection. This approach, which often is associated with significant morbidity, has been deemed necessary because of the uncertainty of diagnosis, symptomatology, and involvement of vital structures. Also, there is a lack of other reliable therapy for this clinically aggressive yet histologically benign disease characterized by an overreactive inflammatory response. The authors treated 2 cases of abdominal IPT with nonsteroidal antiinflammatory drug (NSAID) with successful results. After a diagnosis of IPT on tumor biopsy, an NSAID trial can confirm the diagnosis and treat the disease by causing tumor shrinkage and eventual resolution. Excision remains indicated in easily resectable tumors and in nonresponders to NSAID therapy.

Adolescent↗
PubMed2000

Differences in genotypes of Helicobacter pylori from different human populations.

DNA motifs at several informative loci in more than 500 strains of Helicobacter pylori from five continents were studied by PCR and sequencing to gain insights into the evolution of this gastric pathogen. Five types of deletion, insertion, and substitution motifs were found at the right end of the H. pylori cag pathogenicity island. Of the three most common motifs, type I predominated in Spaniards, native Peruvians, and Guatemalan Ladinos (mixed Amerindian-European ancestry) and also in native Africans and U.S. residents; type II predominated among Japanese and Chinese; and type III predominated in Indians from Calcutta. Sequences in the cagA gene and in vacAm1 type alleles of the vacuolating cytotoxin gene (vacA) of strains from native Peruvians were also more like those from Spaniards than those from Asians. These indications of relatedness of Latin American and Spanish strains, despite the closer genetic relatedness of Amerindian and Asian people themselves, lead us to suggest that H. pylori may have been brought to the New World by European conquerors and colonists about 500 years ago. This thinking, in turn, suggests that H. pylori infection might have become widespread in people quite recently in human evolution.

Amino Acid Isomerases↗
PubMed2000

Immunohistochemical analysis of human CD5 positive B cells: mantle cells and mantle cell lymphoma are not equivalent in terms of CD5 expression.

CD5 is expressed by most T cells and a subset of B cells. Human CD5 positive B cells are present in fetal lymphoid tissue, their frequency decreasing with fetal age. In adult human tissues, CD5 positive B cells have been reported to be present in the germinal centre and mantle zone. Malignancies of CD5 positive B cells include mantle cell lymphoma and chronic lymphocytic leukemia. This report describes an immunohistochemical staining technique used to visualise the expression of CD5 by B cells in human fetal intestine, tonsil, and mantle cell lymphoma. B cells in fetal intestine, tonsillar epithelium, and mantle cell lymphoma all had a similar high intensity of CD5 expression. In contrast, CD5 B cells in the mantle and germinal centre expressed very small amounts of CD5, below the threshold of the technique. Therefore, mantle cells and mantle cell lymphoma are not equivalent in terms of CD5 expression.

Adult↗
PubMed2000

Retroperitoneal soft-tissue sarcomas: prognosis and treatment of primary and recurrent disease.

Soft-tissue sarcomas of the retroperitoneum constitute a heterogeneous group of tumors with varying histology, potential for complete resection, and propensity for recurrent disease-making the development of effective treatment difficult and challenging. A retrospective review of 23 patients with retroperitoneal sarcomas from 1985 through 1998 was performed to assess the biological behavior and clinical outcomes and to identify factors that may influence prognosis and optimize treatment strategy. Liposarcomas were the most common pathology (61%); 79 per cent of these were of low grade. Leiomyosarcomas were the next most common pathology (30%); 43 per cent of these were of low grade. Low-grade sarcomas overall accounted for 62 per cent of the total group. Low-grade tumors independent of histologic type exhibited good prognosis for long-term survival with a median survival of 44 months. In contrast, intermediate- or high-grade tumors were associated with a median survival of only 9 months (P < 0.02). On the other hand, tumor histologic type independent of grade did not have a significant survival difference. Complete tumor resection was possible in 21 of 23 patients, which gives an overall resectability rate of 91 per cent. Eight patients (36%) remain disease-free after initial surgical treatment. However, local recurrence was common; this occurred in 11 of 22 patients (50%). Local recurrence, however, did not preclude long-term survival. Surgical resection of recurrent disease was done in nine patients with a median survival of 91 months (range 24-150 months). Three patients had as many as three operations for recurrent disease. With subsequent recurrences there was a decrease in interval from approximately 4 years to 2 years, and 33 per cent of these patients developed tumor dedifferentiation to high grade. An aggressive surgical approach with reoperation can produce prolonged survival in patients with low-grade retroperitoneal sarcoma.

Adult↗
PubMed2000

Effect of all-trans retinoic acid on growth of xenograft tumor and its metastasis in nude mice.

OBJECTIVE: To study the effect of all-trans retinoic acid on growth of xenograft tumor and its metastasis in nude mice. METHODS: Human gastric cancer BGC-823 and MKN-45 cells were inoculated into spleen subcapsule of nude mice, respectively. The nude mice were subsequently administered with all-trans retinoic acid every other day. Food consuming and body weight of nude mice were measured weekly. Six weeks later, the nude mice were killed. Xenograft tumors in spleen and metastatic tumors in liver were pathologically examined. Microvessel density in the tumors was detected immunohistochemically, and serum carcinoembryonic antigen was measured by radioimmunoassay. RESULTS: After the nude mice were fed with all-trans retinoic acid, the growth of splenic tumor and its liver metastasis were inhibited and the metastatic rates decreased by 50% (BGC-823) and 33.3% (MKN-45), respectively. The microvessel density in splenic and hepatic tumors reduced by 28.58% and 35.47% (BGC-823), 19.45% and 14.52% (MKN-45), respectively. The concentration of carcinoembryonic antigen decreased by 50.24% (BGC-823) and 48.10% (MKN-45). CONCLUSION: All-trans retinoic acid may effectively inhibit the growth of xenograft tumor in spleen and its metastasis to liver in nude mice, which can be corroborated by the decrease of carcinoembryonic antigen and microvessel density.

Animals↗
PubMed2000

Mechanism of inhibition on activator protein-1 activity by all-trans retinoic acid in gastric cancer cells.

OBJECTIVE: To determine the mechanism of all-trans retinoic acid (ATRA) on growth inhibition in human gastric cancer cells. METHODS: Gastric cancer cell lines: MGC80-3, BGC-823, SGC-7901 and MKN-45. CAT assay, Northern blot, Western blot, gene transfection and MTT assay. RESULTS: ATRA can inhibit the activator protein-1 (AP-1) activity in ATRA-sensitive cell lines, but not in ATRA-resistant cell line, and the anti-AP-1 activity of ATRA is mediated by its receptor, retinoic acid receptor alpha (RAR alpha). ATRA can also inhibit the expression of cJun and cFos. One of the mechanisms for ATRA to inhibit the growth of gastric cancer cells may be through its inhibitory effect on the AP-1 activity and its influence on up-regulation of RAR alpha expression. The inhibition of cJun and cFos expressions by ATRA may also contribute to the anti-AP-1 activity. CONCLUSIONS: ATRA inhibits the growth of gastric cancer cells through the regulation of AP-1 activity. This action is mediated by RAR alpha.

Antineoplastic Agents↗
PubMed2000

[Study on lipids and other volatile constituents in Pheretima aspergillum].

To study chemical constituents in Pheretima aspergillum, three kinds of fractions were obtained from this drug by soxhlet extraction with different solvents, and the chemical structures of thirty-six volatile components were identified by means of GC-MS. The eleven in ether fraction were all lipids and the relative content of non-saturated fatty acid was the highest(27.70%) such as oleic acid, linoleic acid, arachidonic acid and eicosatrienoic acid; There were eight lipids in acetone fraction (35.75%), which included one kind of nonsaturated fatty acid (linoleic acid); There were thirteen lipids in ethanol fraction (72.09%), which non-saturated fatty acid has never been detected. This study has determined the lipid composition in Pheretima aspergillum, especially non-saturated fatty acid, and afforded chemical base to cardio-cerebro-vascular therapy.

Animals↗
PubMed2000

[Establishment of ELISA for measuring phenytoin in serum].

OBJECTIVE: To develop a solid phase, competitive enzyme immunoassay for the measurement of serum phenytoin. METHODS: The chemical modified phenytoin combined with human serum albumin and then conjugated with horseradish peroxidase (HRP) to produce the enzyme labeled phenytoin (DPH-HSA-HRP). The anti-phenytoin antibody was prepared in this lab. RESULTS: The working range and sensitivity of this method were 2.9-30 micrograms/ml and 2.87 micrograms/ml respectively. The intra-assay coefficient of variation (CV) was 3.3%-10.2% (n = 15) and inter-assay CV was 5.1%-13.2%. The recovery of this method was 90%-96%. No significant interference was observed with phenobarbital, primidone, carbamazepine, and valproic acid. The new assay method was compared with HPLC method. A linear regression analysis yielded a slope of 1.03, an intercept 1.38 and a correlation coefficient 0.97. CONCLUSIONS: This solid phase enzyme immunoassay for serum phenytoin appears to be simple, precise, and accurate. It may be readily adopted in clinical laboratory for therapeutic monitoring of phenytoin level in serum.

Chromatography, High Pressure Liquid↗