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W T Huang

Publications and source records attributed to W T Huang.

At least 19 recordsLinked to original sources
PubMed2004

Controlling chaos with weak periodic signals optimized by a genetic algorithm.

In the present study we develop a relatively novel and effective chaos control approach with a multimode periodic disturbance applied as a control signal and perform an in-depth analysis on this nonfeedback chaos control strategy. Different from previous chaos control schemes, the present method is of two characteristic features: (1) the parameters of the controlling signal are optimized by a genetic algorithm (GA) with the largest Lyapunov exponent used as an index of the stability, and (2) the optimization is justified by a fitness function defined with the target Lyapunov exponent and the controlling power. This novel method is then tested on the noted Rössler and Lorenz systems with and without the presence of noise. The results disclosed that, compared to the existing chaos control methods, the present GA-based control needs only significantly reduced signal power and a shorter transient stage to achieve the preset control goal. The switching control ability and the robustness of the proposed method for cases with sudden change in a system parameter and/or with the presence of noise environment are also demonstrated.

Journal Article↗
PubMed2003

Usefulness of technetium-99m tetrofosmin liver imaging to detect hepatocellular carcinoma and related to expression of P-glycoprotein or multidrug resistance associated protein-a preliminary report.

Technetium-99m Tetrofsomin (Tc-TF) has been shown to be useful in identifying several types of tumors, such as breast, lung, and thyroid cancers. There was no report in the literature for Tc-TF uptake in hepatocellular carcinoma (HCC). The aim of this study was to evaluate the usefulness of Tc-TF liver imaging to detect HCC and investigate the relationship between Tc-TF liver imaging findings and P-glycoprotein (Pgp) and multidrug resistance associated protein (MRP) expression. Before any therapy, 22 patients with HCC were enrolled in this study. Tc-TF liver images were performed l0 minutes after intravenous injection of 20mCi Tc-TF. All patients had liver biopsy or surgery within l week after Tc-TF liver imaging. Immunohistochemical study of the biopsy or resected HCC specimens was performed using anti-human Pgp and MRP antibodies. Twenty of the 22 (90.9%) patients showed negative Tc-TF liver imaging results without significant Tc-TF uptake in HCC, whereas only the remaining 2 (9.1%) patients showed positive Tc-TF liver imaging results with significant Tc-TF uptake in HCC. Positive Pgp expression was observed in 13 of 20 patients with negative Tc-TF liver imaging results, whereas positive MRP expression was observed in 6 of the remaining 7 patients with negative both Tc-TF liver imaging results and Pgp expression. However, negative Pgp expression but positive MRP expression was observed in all of the remaining 2 patients with positive Tc-TF liver imaging results. The correlation between Tc-TF liver imaging findings and Pgp expression was significant and better than between Tc-TF liver imaging findings and MRP expression. Pgp or MRP expression in HCC may induce no significant Tc-TF uptake in HCC resulting in negative Tc-TF liver imaging findings. Therefore, Tc-TF liver imaging is potential to be a non-invasive method to predict Pgp or MRP expression in HCC. However, further studies with a larger series of patients and longer follow-up time are necessary to confirm our findings.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2002

The stage-dependent inhibitory effect of porcine follicular cells on the development of preantral follicles.

The objective of this study was to examine the effects of follicular cells on the in vitro development of porcine preantral follicles. In Experiment 1, one preantral follicle alone (Trt 1) was cocultured with a follicle of the same size with oocytes (Trt 2) or without oocytes (Trt 3). Preantral follicles cultured alone in vitro for 12 days had greater follicle diameters (1017 +/- 96 microm versus 706 +/- 69 or 793 +/- 72 microm, P < 0.05), growth rates (201 +/- 0.3 versus 103 +/- 0.2 or 128 +/- 0.2, P < 0.05) and oocyte survival rates (73% versus 48, or 25%, P < 0.05) than other groups. The inhibitory effects of follicle cells on the growth of preantral follicles and oocyte survival rates were not enhanced by the addition of oocytectomized preantral follicles (Experiment 2). Follicles were cocultured with different sources of follicular cells in other experiments. Coculture with cumulus cells enhanced oocyte survival compared to the control (without coculture) and mural follicular cell groups (Experiment 3). The growth and survival rates of oocytes collected from the group of follicles cocultured with cumulus cells from large antral follicles (>3 mm) were greater (P < 0.05) than those from small antral follicles (<3 mm), or than the control group (without cumulus cells, experiment 4). No significant differences in the follicular diameters (674 +/- 30 microm versus 638 +/- 33 and 655 +/- 28 microm) and growth rate (105% versus 94 and 105%) were observed among the preantral follicles of the different treatments (P > 0.05). Taken together, coculture with the cells from large antral follicles (>3 mm) exerted a significant positive effect on oocyte survival. The growth and oocyte survival of preantral follicle cocultured with the same size of follicles (with or without oocyte) were inhibited. Growth and survival rates of preantral follicles and oocytes are improved by coculturing them with the cumulus cells derived from larger antral follicles.

Animals↗
PubMed2002

Size and P-glycoprotein expression limit 99mTc-tetrofosmin uptake in parathyroid adenomas.

The purpose of this study was to retrospectively evaluate (99m)Tc-tetrofosmin (Tc-TF) uptake in large parathyroid adenomas and to compare the results with their expression of multidrug resistance (MDR)-mediated, 170 kDa, P-glycoprotein (Pgp). Twenty patients with large parathyroid adenomas (larger than 1.5 g), who had undergone early and delayed (10 min and 2 h) Tc-TF parathyroid imaging before operation, were enrolled in this retrospective study. Immunohistochemical analyses were performed on multiple, non-consecutive sections of the 20 parathyroid adenomas and 40 normal control specimens (20 normal parathyroid glands and 16 normal thyroid specimens) to detect Pgp expression. Tc-TF parathyroid imaging accurately localized 17 large parathyroid adenomas, but not the remaining three. The 17 parathyroid adenomas with significant Tc-TF uptake in delayed (2 h) parathyroid images revealed negative Pgp expression, but the three adenomas without significant Tc-TF uptake, as well as 20 normal parathyroid glands and 20 normal thyroid specimens, revealed positive Pgp expression. Therefore, not only the size, but also the expression of Pgp, limited the sensitivity of Tc-TF parathyroid imaging to localize parathyroid adenomas before operation.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2001

Hepatocyte nuclear factors-1alpha, -1beta, and -3beta expressed in the gonad of tilapia (Oreochromis mossambicus).

Hepatocyte nuclear factors (HNFs) are upstream regulators of many liver-specific genes and are involved in many cellular functions in the body, but their existence, expression, and function in gonads are still poorly understood. Here we report on the first cloning of partial cDNAs of HNF-1alpha and -1beta and full HNF-3beta cDNA from a tilapia (Oreochromis mossambicus) liver cDNA library. The deduced amino acid sequence of tilapia HNF-3beta has a 90 to 96% identity with those of other fishes (dwarf gourami, medaka, and zebrafish), 74% with mammals (human, rat, and mouse), and 82% with Xenopus. RT-PCR detected IGF-I and -II and HNF-1alpha, -1beta, and -3beta in both liver and gonads and the identity of the PCR fragments was confirmed by PCR hybridization. Immunoprecipitation and Western blotting also detected all three HNF proteins in both liver and gonads. Expression of HNFs in the gonads of the tilapia suggests that multi-HNFs may form a cascade to regulate gonadal physiology in the bony fish.

Amino Acid Sequence↗
PubMed2001

Involvement of brain glutamate release in pyrogenic fever.

Whether the glutamate release in the organum vasculosum laminae terminalis (OVLT) is attributable to genesis of a pyrogenic fever is unclear. The lack of information led us to evaluate the changes in glutamate concentrations of OVLT during the fever induced by staphylococcal enterotoxin A (SEA) in unanesthetized rabbits. Both the OVLT concentrations of glutamate and the colonic temperatures were simultaneously monitored during systemic injection of SEA, MK801 (an N-methyl-D-aspartate (NMDA) receptor channel blocker), ketamine (an NMDA receptor channel blocker), or normal saline. The extracellular dialysates in the brain were collected using a microdialysis probe previously placed in the OVLT region. The concentrations of glutamate in the microdialysates were measured by a high-pressure liquid chromatography in combination with a fluorescence detector. Systemic administration of SEA (30 ng x kg(-1) I.V.) increased both the concentrations of glutamate in the OVLT and the colonic temperatures. Glutamate appeared to rise slightly earlier than body temperature. Pretreatment or posttreatment with MK801 or ketamine significantly attenuated the SEA-induced augmenting glutamate release in the OVLT and fever in rabbits. The suppression of glutamate release appeared to start slightly earlier than temperature decline. In addition, the SEA-induced fever could be mimicked by direct injection of glutamate or SEA into the OVLT area. The fever induced by intra-OVLT injection of SEA or glutamate was significantly attenuated by pretreatment with an intra-OVLT dose of MK801 (5 microg) or ketamine (10 microg). The results suggest that glutamatergic pathways in the OVLT region are in pyrogenic fever genesis.

Animals↗
PubMed2000

Conditional-cumulant-of-exposure method in logistic missing covariate regression.

We consider estimation in logistic regression where some covariate variables may be missing at random. Satten and Kupper (1993, Journal of the American Statistical Association 88, 200-208) proposed estimating odds ratio parameters using methods based on the probability of exposure. By approximating a partial likelihood, we extend their idea and propose a method that estimates the cumulant-generating function of the missing covariate given observed covariates and surrogates in the controls. Our proposed method first estimates some lower order cumulants of the conditional distribution of the unobserved data and then solves a resulting estimating equation for the logistic regression parameter. A simple version of the proposed method is to replace a missing covariate by the summation of its conditional mean and conditional variance given observed data in the controls. We note that one important property of the proposed method is that, when the validation is only on controls, a class of inverse selection probability weighted semiparametric estimators cannot be applied because selection probabilities on cases are zeroes. The proposed estimator performs well unless the relative risk parameters are large, even though it is technically inconsistent. Small-sample simulations are conducted. We illustrate the method by an example of real data analysis.

Biometry↗
PubMed2000

Staphylococcal enterotoxin A acts through nitric oxide synthase mechanisms in human peripheral blood mononuclear cells to stimulate synthesis of pyrogenic cytokines.

The pyrogenic response to supernatant fluids obtained from human peripheral blood mononuclear cells (PBMC) stimulated with staphylococcal enterotoxin A (SEA) was characteristic of a response to an endogenous pyrogen in that it was brief and monophasic and was destroyed by heating supernatant fluids at 70 degrees C for 30 min. The febrile responses were in parallel with the levels of interleukin-1 (IL-1), tumor necrosis factor (TNF), interferon-gamma (IFN-gamma), IL-2, and IL-6 in supernatant fluids obtained from PBMC treated with SEA. Both the pyrogenicity and the levels of IL-1, TNF, IFN-gamma, IL-2, and IL-6 in supernatant fluids started to rise at 6 to 18 h and reached their peak levels at 24 to 96 h after SEA incubation. Both the fever and the increased levels of IL-1, TNF, IFN-gamma, IL-2, and IL-6 in supernatant fluids obtained from the SEA-stimulated PBMC were decreased by incubating SEA-PBMC with anisomycin (a protein synthesis inhibitor), aminoguanidine (an inhibitor of inducible nitric oxide synthase [NOS]), or dexamethasone (an inhibitor of NOS). The febrile response to supernatant fluids obtained from the SEA-stimulated PBMC was attenuated by adding either anti-IL-1beta, anti-TNF-alpha, or anti-IFN-gamma monoclonal antibody (MAb) to supernatant fluids. The antipyretic effects exerted by anti-IL-1beta MAb were greater than those exerted by anti-TNF-alpha or anti-IFN-gamma MAb. The data suggest that SEA acts through the NOS mechanisms in PBMC to stimulate synthesis of pyrogenic cytokines (in particular, the IL-1beta).

Animals↗
PubMed1999

A trial study of leukocyte labeling with stabilized Tc-99m D,L-HMPAO by methylene blue and sodium phosphate buffer.

UNLABELLED: We attempted to label leukocytes with stabilized Tc-99m D,L-HMPAO by methylene blue and sodium phosphate buffer (S-HMPAO). METHODS: The results were compared with unstabilized Tc-99m D,L-HMPAO (U-HMPAO). U-HMPAO was obtained by reconstituting a commercial vial of D,L-HMPAO. Stabilization of the kit was performed by the addition of methylene blue. The leukocytes were labeled using a modified published method. The test samples of S-HMPAO and U-HMPAO were prepared immediately, and stood for 0.5, 1, 2, 4, and 6 h, respectively, at room temperature before analysis. RESULTS: In comparison with U-HMPAO: (1) the radiochemical purity of S-HMPAO was higher; (2) the labeling efficiencies of S-HMPAO labeled leukocytes were higher and consistent; (3) the viability of S-HMPAO labeled leukocytes was as high as the viability of U-HMPAO labeled leukocytes at any time; and (4) the percentages of disintegrated from S-HMPAO labeled leukocytes in plasma were lower. CONCLUSION: S-HMPAO is more stable than U-HMPAO and can provide higher leukocyte labeling efficiency. S-HMPAO, therefore, has the potential to replace U-HMPAO as a leukocyte-labeling agent.

Appendicitis↗
PubMed1999

Microbial decolorization of azo dyes by Proteus mirabilis.

A bacterium identified as Proteus mirabilis was isolated from acclimated sludge from a dyeing wastewater treatment plant. This strain rapidly decolorized a deep red azo dye solution (RED RBN). Features of the decolorizing process related to biodegradation and biosorption were also studied. Although P. mirabilis displayed good growth in shake culture, color removal was best in anoxic static cultures. For color removal, the optimal pH and temperature were 6.5-7.5 and 30-35 degrees C, respectively. The organism exhibited a remarkable color removal capability, even at a high concentration of azo dye. More than 95% of azo dye was reduced within 20 h at a dye concentration of 1.0 g L-1. Decolorization appears to proceed primarily by enzymatic reduction associated with a minor portion, 13-17%, of biosorption to inactivated microbial cells.

Azo Compounds↗
PubMed1998

Stabilization of Tc-99m D,L-HMPAO preparations as a leucocyte labelling agent.

An attempt was made to use stabilized Tc-99m D,L-HMPAO (S-HMPAO) to label leucocytes. The radiochemical purity of Tc-99m D,L-HMPAO, labelling efficiency of leucocytes, cell viability of labelled leucocytes, and stability of S-HMPAO labelled leucocytes were calculated. In comparison with commercial Tc-99m D,L-HMPAO (C-HMPAO) without stabilization, immediately, at 0.5, 1, 2, 4, and 6 h after HMPAO preparation, the radiochemical purity of S-HMPAO and the labelling efficiencies of S-HMPAO labelled leucocytes were higher. S-HMPAO is more stable than C-HMPAO and can provide higher leucocyte labelling efficiency. S-HMPAO, therefore, has the potential to replace C-HMPAO as a leucocyte-labelling agent.

Cell Survival↗
PubMed1998

Regional influences of the fallopian tubes on the rate of boar sperm capacitation in surgically inseminated gilts.

Aliquots of ejaculated boar semen containing known numbers of spermatozoa were deposited into the caudal isthmus or rostral ampulla of the Fallopian tubes of gilts at, or immediately after, ovulation to assess regional influences on the rate of capacitation. Eggs were recovered during a second intervention 4, 5, 6 or 7 h after surgical insemination and were examined by phase-contrast microscopy. Results were obtained from ten animals in each of the 4-, 5- and 6-h groups and from eight animals in the 7-h group. With two exceptions, fertilized eggs were not recovered until 6 h after insemination into the isthmus, the proportion (45.6%) being significantly greater than the corresponding figure (1.4%) for ampullary insemination (P < 0.001). Similarly, the proportion of fertilized eggs recovered 7 h after insemination into the isthmus (58.7%) was significantly greater than after ampullary insemination (21.9%; P < 0.01). Numbers of spermatozoa associated with the zona pellucida remained low in all these instances, with mean figures per egg ranging from 0.3 to 3.8. Insemination into the isthmus gave a 1-2 h advantage in fertilization compared with insemination into the ampulla. Although relative rates of sperm cell progression to the site of fertilization may have contributed to this, there is strong evidence that rates of capacitation differ significantly in the respective portions of the Fallopian tube. Therefore, attention was focused on: (1) the viscous glycoprotein secretion in the caudal isthmus acting to remove seminal plasma from the sperm surface; and (2) the phase of sperm head binding to the isthmus epithelium. Gradients in local endocrine modulation by the adjacent ovary offer one explanation for the functional specialization of different regions of the Fallopian tubes.

Animals↗
PubMed1997

Mechanisms and sites of pyrogenic action exerted by staphylococcal enterotoxin A in rabbits.

The febrile responses induced by i.v. administrations of staphylococcal enterotoxin A (SEA) was mimicked by direct injection of SEA into the organum vasculosum laminae terminalis (OVLT) in unanesthetized rabbits. Compared with the febrile responses induced by i.v. injection of SEA, the OVLT route of injection required a much lower dose of SEA to produce a similar fever. Furthermore, the fever induced by intra-OVLT or i.v. injection of SEA was significantly attenuated by pretreatment with intra-OVLT injection of anisomycin (a protein synthesis inhibitor), indomethacin or diclofenac (inhibitors of cyclo-oxygenase (COX)), and aminoguanidine or dexamethasone (inhibitors of inducible nitric oxide synthase (iNOS)). These results suggest that COX or iNOS pathway in the OVLT mediate the SEA-induced fever in rabbits.

Animals↗
PubMed1997

The inducible lactose operator-repressor system is functional in the whole animal.

Mouse liver cell lines that bear a stably integrated lactose operon repressor (lacI) gene and a Ha-ras gene linked to a lactose operator-containing SV40 early promoter were generated. When grown in medium containing more than 0.1 mM isopropyl beta-D-thiogalactoside (IPTG), the Ha-ras gene was induced up to 20-fold. Maximum induction of Ha-ras gene expression occurred after 12 h of exposure. The tumorigenicity of these cell lines in syngeneic mice was enhanced when the mice were maintained on drinking water containing 12.5 mM IPTG. Ha-ras gene expression in tumors was strongly induced in the presence of IPTG in vivo. Induction of Ha-ras gene expression in mice was consistently observed after 48 hr of exposure to drinking water containing IPTG. This system provides an approach for studying the function of oncogene in vivo as well as other genes of interest.

Animals↗
PubMed1997

99Tcm-phenylene imine phenol as a potential leukocyte labelling agent.

The aim of this study was to evaluate 99Tcm-labelled phenylene imine phenol (99Tcm-Ph(IP)2) as a leukocyte label. The 99Tcm complex exhibits a neutral lipophilic character. The radiochemical purity of the 99Tcm-Ph(IP)2 was high both soon after labelling (94.5 +/- 1.2%, n = 7) and at 24 h (89.7 +/- 1.0%, n = 7). In a comparative study, the labelling efficiency of 99Tcm-Ph(IP)2 and 99Tcm-hexamethylpropylene amine oxime (99Tcm-HMPAO) labelled leukocytes was 47.1 +/- 3.5% (n = 7) and 58.5 +/- 7.0% (n = 7) respectively. The viability of labelled leukocytes was greater than 90% for both 99Tcm complexes. The elution ratios of labelled leukocytes with 99Tcm-Ph(IP)2 at 1, 4 and 24 h were 10.1 +/- 3.5%, 17.2 +/- 2.7% and 23.0 +/- 2.4% (n = 7) respectively, while those with 99Tcm-HMPAO were 10.8 +/- 1.2%, 18.3 +/- 2.0% and 37.0 +/- 3.7% (n = 7) respectively. In conclusion, 99Tcm-Ph(IP)2, with good stability and significant leukocyte labelling efficiency, is a potential leukocyte label.

Animals↗
PubMed1997

Staphylococcal enterotoxin A-induced fever is associated with increased circulating levels of cytokines in rabbits.

Rabbits were injected intravenously with 10 to 100 ng of staphylococcal enterotoxin A (SEA) per kg, and colonic temperatures were monitored. The febrile responses were compared with circulating levels of interferon (IFN), tumor necrosis factor (TNF), interleukin-1 (IL-1), IL-2, and IL-6 just before the injection of SEA. Both colonic temperatures and circulating levels of IFN, TNF, and IL-2 started to rise at 1 to 2 h and reached their peak levels at 3 to 5 h after SEA injection. Both the fever and the increased circulating levels of IFN, TNF, and IL-2 produced by SEA were decreased by pretreatment with indomethacin (a cyclo-oxygenase inhibitor) (15 mg/kg, intraperitoneally), anisomycin (a protein synthesis inhibitor) (15 mg/kg, subcutaneously), or dexamethasone (an effective anti-inflammatory and immunosuppressive agent) (4 mg/kg, intravenously) in rabbits. Rabbits were injected intravenously with 30 ng of SEA per kg on four consecutive days, and colonic temperatures were monitored. Compared to rabbits that received the single injection of SEA, rabbits that received four consecutive injections of SEA showed a lesser increase in circulating levels of IFN, TNF, and IL-2 as well as colonic temperatures in response to an intravenous dose of SEA (30 ng/kg). The data suggest that the prevention of the febrile response elicited by SEA by indomethacin, anisomycin, or dexamethasone is due to prevention by these compounds of the increase in the circulating levels of IFN, TNF, and IL-2. The pyrogenic hyporesponsiveness to repeated injection of SEA is associated with decreased production of these circulating cytokines.

Animals↗
PubMed1995

Suppression of natural killer cell activity in mouse spleen lymphocytes by several dopamine receptor antagonists.

The effects of dopaminergic receptor inhibitors such as thiothixine (D1/D2), fluphenazine (D1/D2), trifluoperazine (D1/D2), pimozide (D2), flupenthixol (D1/D2), (+/-)-SKF 83566 (D1), and spiperone (D2) on splenic natural killer (NK) cell cytotoxic activities were assessed in vitro using mouse spleen lymphocytes or enriched NK cells. Both the activities of the splenic NK cell cytotoxicity and the effector-target cell conjugation were suppressed by thiothixine, fluphenazine, and trifluoperazine at concentrations from 2.64 to 14.78 microM. In addition, the augmentation of the cytolytic activity of NK cells induced by interferon-alpha or interleukin-2 was antagonized by pretreatment with these neuroleptic compounds. However, neither the splenic NK cell cytotoxicity nor the effector-target cell conjugation were affected by treatment with other neuroleptic compounds such as pimozide, flupenthixol, (+/-)-SKF 83566, and spiperone. Thus, it appears that neuroleptic compounds such as thiothixine, fluphenazine, and trifluoperazine may act through the mechanisms other than a dopaminergic pathway to affect the NK cell-target cell interaction.

2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-ben↗