Biomedical subjects

D S Wang

Publications and source records attributed to D S Wang.

At least 73 records · Page 4Linked to original sources

PubMed1996

Increase of vascular endothelial growth factor mRNA expression by 1,25-dihydroxyvitamin D3 in human osteoblast-like cells.

Vascular endothelial growth factor (VEGF), a secreted endothelial cell-specific mitogen, is produced in endocrine organs and regulated by trophic hormones. Because angiogenesis and osteogenesis are closely regulated, we studied whether human osteoblast-like cells produce VEGF, and if so, what factors regulate VEGF mRNA expression. Human osteoblast-like cells (HObLC) derived from trabecular bone explants were cultured in alpha-MEM supplemented with 10% fetal calf serum. Northern blot analysis revealed that HObLC expressed VEGF mRNA, as did several human osteosarcoma cells. 1,25-(OH)2D3 increased the steady-state levels of VEGF mRNA in a time- and concentration-dependent manner in HObLC and one of the osteosarcoma cell lines, SaOS-2, accompanied by an increase in the concentration of immunoreactive VEGF in the conditioned medium. PTH and IGF-I also increased the level of VEGF mRNA in HObLC and SaOS-2 cells. Furthermore, 12-O-tetradecanoylphorbol ester stimulated VEGF mRNA in a time-and concentration-dependent manner. The VEGF mRNA expression induced by 1,25-(OH)2D3 was completely inhibited by H-7, but only partially by staurosporine. We have demonstrated that PTH, IGF-I, and most potently 1,25-(OH)2D3 stimulate the mRNA expression and secretion of VEGF in human osteoblast-like cells, suggesting that one of the anabolic effects of 1,25-(OH)2D3 on skeletal tissue may be mediated by VEGF produced by osteoblasts.

Autoradiography↗

PubMed1996

Acceleration of skin graft healing by growth factors.

A special local burn wound treatment, using a healing promotion factor, attempted to achieve earlier wound closure. Clinically it is not difficult to harvest autologous human platelet-derived wound healing factor (HPDWHF) from burn patients. Another study has proved that porcine pituitary extract (PPE) could be one of the supplements for growing human keratinocytes in vitro (Wang HJ, Chen TM, Tung YM et al. Burns 1995). Initially, using the ELISA immunoassay, we detected titres of platelet-derived growth factor heterodimer AB (PDGF-AB) and epidermal growth factor (EGF) in HPDWHF and PPE. After elevating a 6 X 9 cm2 flap on the backs of Sprague-Dawley (SD) rats 1 ml of heterologous HPDWHF and PPE were sprayed topically on the wound and followed by grafting six pieces of 1 cm2 autologous full-thickness skin. The flap wound was then closed with a piece of large-pore Biobrane interposed between the skin graft wound and the flap. On postgraft day 7, the wound was reopened to measure the area of the full-thickness skin graft (FTSG) using micrographic paper; the results are reported as the percentage of graft expansion beyond the original size. In the cytokine study, we found that the concentrations of PDGF-AB dimer in HPDWHF and PPE were 5222 +/- 102 and 375 +/- 12 pg/ml (both values are reported after a 1:10 dilution) (n = 3), whereas the EGF concentration was 245 +/- 9 pg/ml, and undetectable in undiluted PPE (n = 3), thereby proving that the PDGF-AB and EGF fibres in the HPDWHF were significantly higher than in the PPE Both the HPDWHF (n = 6, with each animal grafted with six skin graft samples) and PPE (n = 7) demonstrated significant accelerations of FTSG growth, with 14.41 +/- 1.08 per cent and 13.16 +/- 3.25 per cent increases in the FTSG size when compared to the sham control group 1.39 +/- 3.26 per cent (n = 5) (P < 0.05). Comparisons between the treatment groups showed no evidence to indicate that the HPDWHF is superior to the PPE in accelerating FTSG growth (P > 0.05). This supports the hypothesis that PDGF appears to transduce its signal through wound macrophages and may trigger the induction of positive autocrine feedback loops and synthesis of endogenous wound PDGF and other growth factors, thereby enhancing the cascade of tissue repair (Pierce GF, Mustoe TA, Altrock B et al. 1991; J Cell Biochem 1991; 45: 319-326), and the effect that PDGF-AB on wound healing is not dose dependent (Mustoe TA, Cutler NR, Allman RM et al. Arch Surg 1994; 129: 213-219). In future studies we expect to show that autologous HPDWHF and heterologous PPE will promote skin graft wound healing in burn patients since they contain a high concentration of PDGF-AB.

Adult↗

PubMed1996

Interleukin-6 (IL-6) inhibits thyroid function in the presence of soluble IL-6 receptor in cultured human thyroid follicles.

Interleukin-6 (IL-6), a pleiotropic cytokine, is postulated to be involved in the pathogenesis of sick euthyroid syndrome, although the direct in vitro effects of IL-6 on human thyroid function are controversial. Because IL-6 signal can be transduced when the complex of IL-6 and soluble IL-6 receptor (sIL-6R) binds to gp 130, an IL-6 signal transducer, we studied the effects of IL-6 and sIL-6R on thyroid function, using human thyroid follicles obtained from patients with Graves' disease. IL-6 alone had no inhibitory effect on TSH-induced thyroid function (125I incorporation and organic 125I release), even at supraphysiological concentrations. However, in the presence of physiological concentrations of sIL-6R (100 ng/ml), IL-6 inhibited thyroid function dose dependently and completely, accompanied with the decreased ratio of 125I-T3/125I-T4 not only in the thyroid follicles but also in the culture medium. Thyroid follicles did not secrete sIL-6R but produced IL-6 constitutively. Consistent with these findings, sIL-6R inhibited thyroid function slightly at high concentrations. Furthermore, RT-PCR analyses revealed that human thyroid follicles expressed the messenger RNAs for IL-6 and gp130 but scarcely messenger RNA for IL-6R. These in vitro findings suggest that IL-6 alone hardly affects thyroid function in thyroid follicles in which IL-6R gene is scarcely expressed. However, because sIL-6R is present abundantly in serum, IL-6 in vivo would be capable of inhibiting the synthesis and release of T4 and, to a greater extent, T3 from the thyroid gland. These in vitro findings are at least partly related to the development of sick euthyroid syndrome.

Analysis of Variance↗

PubMed1996

Enhancement of the antitumor effect of gamma-ray irradiation in combination with camptothecin against human colorectal adenocarcinoma.

The effect of gamma-ray irradiation and camptothecin (CAM) on human colorectal adenocarcinoma (LS 174T) growth was examined. On inhibition of DNA synthesis of LS 174T cells, almost all combined treatments presented a synergistic effect, excepting that the additive effects were shown at the lowest or the highest doses of CAM prior to the gamma-ray (137Cs) irradiation. The in vivo antitumor activity of 131I-NCC-CO-411 monoclonal antibody against carcinoembryonic antigen in combination with CAM was assessed by a tumor growth rate in LS 174T tumor-bearing nude mice. The tumor growth of the combined group was supra-additively suppressed in comparison with that of the individual group. The results suggest that the efficacy of radioimmunotherapy may be enhanced by combination treatment with CAM. A clinical protocol involving a combination treatment with CAM is underway.

Adenocarcinoma↗

PubMed1996

Accumulation of NCC-CO-411 monoclonal antibody in human colorectal adenocarcinoma through binding of the released carcinoembryonic antigen in nude mice.

NCC-CO-411, an anti-carcinoembryonic antigen (CEA) monoclonal antibody (MoAb) showed a dose-dependent reactivity with standard CEA, but did not bind to the CEA anchoring with cell membranes. When LS 174T cells, one of the CEA-producing cells, were treated with phosphatidylinositol-specific phospholipase C, NCC-CO-411 MoAb recognized the released CEA containing glycosylphosphatidylinositol as well as the standard CEA. The binding activity of NCC-CO-411 MoAb with CEA was also demonstrated by the immunostaining of the LS 174T colorectal tumor xenograft tissues. The biodistribution study showed that NCC-CO-411 MoAb was mainly taken up by tumor and kidney, while the anti-hCEA MoAb was largely concentrated in liver and spleen rather than in the tumor. These results suggest that NCC-CO-411 MoAb recognizes the released CEA and gives an excellent tumor image in LS 174T tumor-bearing mice.

Adenocarcinoma↗

PubMed1996

[Clinical and experimental study on effects of yinchen wuling powder in preventing and treating hyperlipoproteinemia].

Sixty cases with hyperlipoproteinemia (30 cases each group) were observed. The total effective rate of the treated group with Yinchen Wuling Powder was 93.3%. And that of the control group with Gynostemma pentophyllum capsule was 86.7%. The result revealed that significant difference existed between the above-mentioned two groups (P < 0.01). According to the animal experiment, on both prevention and treatment, this recipe could inhibit the increase of the hyperlipemia model rat's serum TCh, TG, LDL-C and the ratio of LDL-C/HDL-C (P < 0.01). Besides, this recipe had the effect of marked antioxidation. It could reduce the level of peroxidative lipids, and strengthen the glutathion peroxidase activities.

Animals↗

PubMed1996

[Co-regulative effect of PKA-RII and PKC-alpha kinase subspecies on expression of c-myc and c-H-ras in human gastric cancer cells (MGC 80-3)].

Based on preceding experiment, we further studied the co-regulative effects of PKA-R II and PKC-alpha on expression of oncogenes in human gastric cell line MGC 80-3. The c-myc and c-H-ras expression were suppressed in MGC 80-3 cells during HMBA-induced differentiation. At the same time, PKA-R II showed nuclear translocation from cytoplasm, whereas the expression of PKC-alpha shifted from nucleus to cytoplasm. PKA inhibitor (Sigma) was added to block cAMP-PKA pathway when cell differentiation were induced by HMBA. The PKA-R II was still located in cytoplasm but expression of PKC-alpha translocated again into nucleus. Meanwhile, the c-myc and c-H-ras again expressed. This suggested that the changing regulation of oncogene expression were closely related to signalling from nuclear translocation of kinase subspecies. It thus shows the co-regulation effects of two signal system on oncogenes expression.

Carrier Proteins↗

PubMed1996

Diacetylamethystoidin A protects isolated working rat heart against myocardial reperfusion injury.

AIM: To observe the effect of diacetylamethystoidin A (6 alpha, 13 beta-diacetyl-11, 15-dioxo-19-hydroxyl-kaurene, DAA-A) on myocardial ischemia reperfusion injury. METHODS: Working heart mode was induced in isolated rat heart subjected to a 40-min ceasing perfusion followed by a 25-min reperfusion. RESULTS: DAA-A 0.13, 0.25, 0.50 mmol.L-1 reduced the incidence of ventricular fibrillation (1, 1, 0 vs 4 in Vehicle and 5 in Control, respectively), increased the coronary flow (mL.min-1, 1.8 +/- 0.9, 1.9 +/- 0.8, 1.7 +/- 0.6 vs 1.0 +/- 0.3 in Vehicle and 0.9 +/- 0.5 in Control as reperfusion time 5 min, respectively), improved the contractile function of heart, decreased the release of lactic dehydrogenase (LDH) and malondialdehyde (MDA). DAA-A 0.25 mmol.L-1 reduced the injury of myocardial cell ultrastructure. CONCLUSION: DAA-A has cardioprotective effect through diminishing cellular lipid peroxidation induced by oxygen free radicals.

Animals↗

PubMed1995

The association of the C-terminal region of beta I sigma II spectrin to brain membranes is mediated by a PH domain, does not require membrane proteins, and coincides with a inositol-1,4,5 triphosphate binding site.

The beta spectrin genes each produce two alternate transcripts the longer of which has a approximately 210 amino acid C-terminal extension including a pleckstrin homology (PH) domain and also an uncharacterized membrane binding site. GST constructs including the entire or the N-terminal segment of the beta I sigma II spectrin PH domain bind to crude and extracted brain membranes, to protein free brain lipid and to vesicles containing phosphatidylinositol-4,5-bisphosphate. This PH domain also binds radiolabelled inositol-1,4,5-trisphosphate (IP3) and preincubation with IP3 inhibits binding to extracted brain membranes. We conclude that membrane binding of the beta I sigma II spectrin C-terminal region is by means of a direct interaction between the N-terminal region of the PH domain and membrane lipids and does not require membrane protein. The PH domain of the beta-adrenergic receptor kinase showed different binding properties in every assay employed, showing that different PH domains may have different membrane binding specificity.

Animals↗

PubMed1995

Binding of pleckstrin homology domains to WD40/beta-transducin repeat containing segments of the protein product of the Lis-1 gene.

In previous experiments we demonstrated an interaction between certain pleckstrin homology (PH) domains and regions containing the so-called WD40 (or beta-transducin) repeats of the beta subunit of trimeric G-proteins (G beta), a finding we here extend to the PH domains of the src-related tyrosine kinase TecIIa and the GTPase dynamin. To examine the possibility that WD40 repeats in molecules other than G beta might also bind PH domains we examined PAFAH-45, the protein product of the Lis-1 gene, which contains 7 WD40 repeats. We found that 1) Purified PAFAH-45 binds PH domain constructs in vitro. 2) Protein constructs expressing all 7 WD40 repeats of PAFAH-45 but lacking the N-terminal non WD40 region also bind PH domains of beta-adrenergic receptor kinase, beta-spectrin, TecIIa and dynamin but with a differing hierarchy of affinities than that seen with G beta. 3). PAFAH-45 WD40 repeats will reduce the binding of PH domains to brain G beta and brain G beta gamma will reduce the binding of PH domains to PAFAH-45. These data support the hypothesis that PH domain/WD40 interactions are involved in a wide variety of important protein/protein interactions.

Animals↗

PubMed1995

Natural co-occurrence of Fusarium toxins and aflatoxin B1 in corn for feed in north Vietnam.

Natural occurrence of Fusarium mycotoxins (trichothecenes and fumonisins) and aflatoxin B1 (AFB1) were surveyed in 32 corn samples, harvested in 1993 and randomly sampled in 1994 in several districts of Hanoi, Vietnam. Corn samples were first milled into fine powder, extracted with methanol-water (3:1) and the crude extracts obtained from the same samples were used for the simultaneous analysis of the trichothecenes such as nivalenol (NIV), deoxynivalenol (DON), and T-2 toxin (T-2) by gas chromatography/mass spectrometry (GC/NS); fumonisins B1 (FB1), B2 (FB2), and B3 (FB3) by high-performance liquid chromatography (HPLC) with a flourescence detector; and AFB1 by and ELISA kit based on a monoclonal antibody. The data revealed that 14, 8, 4, 3, and 2 out of 15 corn kernel samples were positive for AFB1, FB1, FB2, FB3, and NIV with the average levels being 28, 1, 101, 276, 232, and 858 ppb, respectively, and neither DON nor T-2 were detected. As for the other 17 samples of corn powder, 13, 15, 12, 10, 4 and 2 were positive for AFB1, FB1, FB2, FB3, DON, and NIV with the average being 30, 780, 289, 176, 3, 170, and 1,365 ppb, respectively, and T-2 was not detected. Although their positive rates and levels fell in the ranges reported elsewhere, it was found for the first time that the Fusarium toxins (NIV, DON, and fumonisins) and an Aspergillus toxin (AFB1) were naturally co-contaminated in selected samples of corn produced in north Vietnam.

Aflatoxin B1↗

PubMed1995

Regional skin blood flow in deep burn wounds: a preliminary report.

Local skin blood flow (LSBF) using the Walker's deep burn rat model was studied on the first three postburn days using the carbon-14 iodoantipyrine ([14C]IAP) perfusion method. The radioactive [14C]IAP (12.5 microCi) was infused through the femoral vein over a period of 30 seconds and the blood samples were collected by a free flow from the femoral artery at 5-s intervals to evaluate the concentration of the isotope, in the blood. At the conclusion of the infusion, the rats were guillotined and biopsies were obtained from the burned skin, unburned skin from burned rats and skin from sham control rats to assay the isotope in the skin. The LSBF was calculated from the skin tissue and plasma radioactivity data using Jay's equation. The results showed significant decreases of the skin blood flow in the deep burn wound with 4.05 +/- 1.16, 5.31 +/- 1.32 and 4.77 +/- 2.48 ml/100 g/min as compared to the LSBF of unburned skin 10.27 +/- 1.49, 12.39 +/- 2.05, 14.79 +/- 1.85 ml/100 g/min on postburn days 1, 2 and 3 (P < 0.05). The blood flow of the control group skin was 11.5 +/- 1.97 ml/100 g/min (P < 0.05). There were also significant differences of LSBF among burn wounds on postburn days 1, 2 and 3 (P < 0.05). Pathological study of the deep burn wound showed that more of the blood flow was in the subcutaneous adjacent areolar tissue, than in the deep reticular dermis, and only a little occurred in the upper reticular dermis occasionally.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1995

[The regulation of calmodulin in the cell cycle].

In order to study the role of calmodulin (CaM) in the cell cycle, RC 3 cells carring the CaM expression vectors which was constructed by joining the CaM cDNA with a plasmid of mouse mammary tumor virus (MMTV), were used in this experiment. The CaM expression vectors transcription is regulated by a dexamethasone (DXM) inducible MMTV LTR promoter. Upon addition of DXM, cells have transiently increased CaM mRNA and protein levels. Increased CaM caused a acceleration of proliferation. Flow cytometric analysis showed that progression though G1, G2 and metaphase was accelerated by increase in CaM levels, while treatment with the CaM antagonist trifluoperazine (TFP) blocked cell cycle progression at G1/S boundary and during G2/M and metaphase. The studies have shown that CaM is important in controlling progression at three points in the cell cycle: (1) The G1/S boundary to permit the initiation of DNA synthesis; (2) The G2/M boundary to permit the initiation of mitosis; (3) At the metaphase/anaphase transition of mitosis to permit chromosome segration and the completion of mitosis. This study indicates that the RC 3 cell is a useful experimental cell model for studing the effect of a transient increase of intracellular CaM levels on control of cell cycle.

3T3 Cells↗

PubMed1995

Quantitative analysis of (l)-ephedrine and (d)-pseudoephedrine in plasma by high-performance liquid chromatography with fluorescence detection.

Quantitative analysis of (l)-ephedrine (l-Ep) and (d)-pseudoephedrine (d-Ps) in plasma by high-performance liquid chromatography (HPLC) is described. The newly developed method is based on a precolumn derivatization with 5-dimethyl-aminonaphthalene-1-sulfonyl chloride (DNSC1) in acetonitrile. The diastereomers formed were separated on a reversed phase column by HPLC with fluorescence detection employing 0.6% phosphate buffer (pH 6.5)-methanol (3:8, v/v) as mobile phase. The detection limit of each Ephedra alkaloid stereoisomer was 0.5 ng at a signal-to-noise ratio of 3:1, the linear response to each stereoisomer being 1-800 ng.ml-1. The plasma level profile of l-Ep and d-Ps in guinea pig was investigated by this method. The determination of l-Ep and d-Ps in plasma of a volunteer after oral administration of Xiao Qinglong Heji was also performed.

Animals↗

PubMed1994

Binding of PH domains of beta-adrenergic receptor kinase and beta-spectrin to WD40/beta-transducin repeat containing regions of the beta-subunit of trimeric G-proteins.

Pleckstrin homology (PH) domains are found in numerous proteins important in signal transduction and cytoskeletal function. Several PH domains are now known to contain a binding site for the beta gamma subunits of trimeric G-proteins (G beta gamma), a finding which naturally raises the question of where on the G beta gamma complex these PH domains bind. Here we demonstrate binding of the PH domains of beta-adrenergic receptor kinase and beta-spectrin to the G beta subunit and not the G gamma subunit in a nitrocellulose gel replica assay. Furthermore, the C-terminal tryptic fragment of G beta containing only 5 WD40/beta-transducin (WD40) repeats also binds these two PH domains. Finally, constructs containing only WD40 repeats of G beta were shown to bind to beta-ARK and beta-spectrin PH domains in solution. These findings suggest that WD40 repeats of G beta are ligands for PH domains and have interesting implications for other proteins containing WD40 sequences.

Amino Acid Sequence↗

PubMed1994

Potential importance of tissue angiotensin-converting enzyme inhibition in preventing neointima formation.

BACKGROUND: Angiotensin II (Ang II) induces vascular smooth muscle cell migration and growth in vitro and induces DNA synthesis in vascular smooth muscle in vivo. Angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor antagonists inhibit neointimal hyperplasia in many experimental models of restenosis. However, recent clinical trials (MERCATOR and MARCATOR) reported that treatment with low (antihypertensive) doses of an ACE inhibitor (cilazapril) failed to prevent restenosis. Because ACE activity is induced in the neointima after injury, we hypothesize that the inhibition of neointimal development may be dependent on the suppression of tissue ACE activity, which in turn is dependent on the dose of the ACE inhibitor. METHODS AND RESULTS: To test this hypothesis, we treated rats with increasing doses of an ACE inhibitor, quinapril, before injury of the carotid artery. Blood pressure, serum and tissue ACE activity, and neointimal area were measured. The results demonstrated a dose-dependent inhibition by quinapril of serum and tissue ACE activities and neointima formation. However, the IC50s for blood pressure reduction and serum ACE inhibition were significantly lower than that observed for the suppression of neointima formation. The degree of neointimal formation showed a better correlation with residual tissue ACE than with serum ACE or blood pressure. CONCLUSIONS: These results demonstrate a dissociation of the ability of an ACE inhibitor to decrease blood pressure and inhibit circulating ACE activity from its ability to inhibit tissue ACE activity. These results suggest that the need for a higher dose of an ACE inhibitor for the inhibition of neointima formation may be due to the relative difficulty in inhibiting tissue ACE activity.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1994

Induction of angiotensin converting enzyme in the neointima after vascular injury. Possible role in restenosis.

Angiotensin II (Ang II) promotes growth of vascular smooth muscle cells in vitro. Consistent with this, Ang II enhances neointimal proliferation in vivo after vascular injury, while angiotensin converting enzyme (ACE) inhibitors attenuate this process. Since tissue ACE plays a key role in the control of local Ang II production, we examined whether vascular injury resulted in an increase in vascular ACE expression that may result in increased Ang II production. Abdominal aorta of Sprague-Dawley rats were injured with a 2 French balloon catheter. Morphometrical changes, ACE enzymatic activity, and localization of ACE by immunohistochemistry in injured and uninjured aorta were analyzed. Vascular ACE activity in the injured aorta was significantly higher than in the uninjured aorta, while serum and lung ACE levels were not different between the two groups. The cellular distribution of the ACE protein in the neointima was similar to that of alpha smooth muscle actin but differed from those of endothelial (von Willebrand factor) or monocytes/macrophages (ED-1) markers, demonstrating that ACE was expressed in neointimal smooth muscle cells. These data demonstrate that vascular injury results in the induction of vascular ACE and suggest that the inhibition of vascular ACE may be important in the prevention of restenosis after balloon injury.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1994

Production and characterization of sterigmatocystin.

Fourteen strains of Aspergillus versicolor and 2 strains of A. nidulans were screened for sterigmatocystin (ST) production on a semi-synthetic solid substrate by high performance liquid chromatography (HPLC) analysis. Two strains of A. versicolor producing ST at 550.5 mg.kg-1 substrate and 1160.8 mg.kg-1 substrate were selected to inoculate 4 kg solid ST-producing media. After 30 days stationary incubation at 28 degrees C in the dark, 2271.6 mg of pale-yellow needle-shaped crystals were isolated and purified from the culture with a procedure applying column chromatography and recrystallization method. The crystal was proved to be sterigmatocystin by spectroanalysis and some physico-chemical analysis. The purity of the final material obtained were more than 99.9% as shown by HPLC and TLC detection. With this procedure, ST was obtained at about one tenth of its commercial cost.

Aspergillus↗