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Biomedical subjects

J C Huang

Publications and source records attributed to J C Huang.

At least 19 recordsLinked to original sources
PubMed2002

Co-removal of hexavalent chromium during copper precipitation.

In our recent study using the nucleated precipitation technology to treat plating wastewater, it was found that about one half of hexavalent chromium was co-removed with copper, nickel and zinc. Since hexavalent chromium could not react with either hydroxide or carbonate to from precipitates, this study was undertaken to evaluate the mechanism(s) involved in the chromium co-removal. Batch tests were conducted with synthetic solutions containing either only copper or both copper and hexavalent chromium. Metal precipitation was induced by adding Na2CO3 to different pH, and the quantitative removal of copper and chromium was determined. Besides, the [Cr]/[Cu] molar ratio of produced precipitates were also assessed in conjunction with the EDAX analysis to determine their compositions. Experimental results indicate that for pure copper solution, precipitation begins at pH 6.0, and completes at pH 7.0. The chemical forms of the precipitates are copper carbonates [CuCO3 x Cu(OH)2 and CuCO3 x 2Cu(OH)2]. On the other hand, in a bi-metal solution of copper plus chromium, precipitation of copper begins at about pH 5.0, and copper precipitation is always accompanied by some chromium removal. From the removal stoichiometry of the two metals, it is found that at low pH, the co-removal is a result of "co-precipitation" which results in the formation of CuCrO4 crystallites. Once such crystallites are formed, they provide a heterogeneous environment which enhances an early formation of copper carbonate at a lower pH (below 5.5). It is further found that once copper carbonate precipitates are produced, the remaining soluble will precipitate in such form, and at this stage further removal of copper is no longer accompanied by additional chromium removal. The test data also reflect that the produced copper carbonates are positively charged, as verified by zeta potential measurement, at pH below 7.5. Thus they are able to adsorb some anionic chromium (existing as chromate) through electrostatic attraction and/or inorganic ligand exchange. At pH of 6 to 10, the extent of adsorption decreases with increasing pH, and the adsorption capacity seems to coincide with the progressive reduction of positive zeta potentials of the precipitated particles.

Adsorption↗
PubMed2001

X-ray absorption spectroscopy study of Co structure in the epitaxial Co/Pt multilayers on Al2O3(11-20) substrates.

In this study, five epitaxial [Co(t nm)/Pt(1 nm)]30, multilayer samples (t=0.16-1.07 nm) were studied using polarized X-ray absorption spectroscopy method. These samples were prepared on Mo(110)/ Al2O3(11-20) substrates by MBE technique. The results show that the Co layer is more like an fcc pseudomorphic structure for the Co thickness of less than 0.3 nm. For Co layer thickness of 1 nm, the first shell distance is 0.25 nm, which is very close to the Co-Co distance of bulk hcp Co. On the other hand, for Co layer of less than 0.3 nm, the in plane first shell distance is expanded by 4% and most of the neighboring atoms are Pt atoms. The fitting results of the Co/Pt multilayers seem to support a sharp boundary model rather than an interdiffusion model.

Journal Article↗
PubMed2001

Low-dose dexamethasone effectively prevents postoperative nausea and vomiting after ambulatory laparoscopic surgery.

PURPOSE: To evaluate the prophylactic effect of low-dose dexamethasone (5 mg) on postoperative nausea and vomiting (PONV) in women undergoing ambulatory laparoscopic surgery. Metoclopramide and saline served as controls. METHODS: One hundred twenty women (n=40 in each of the three groups) undergoing ambulatory laparoscopic tubal ligation under general anesthesia were enrolled in this randomized, double-blinded, placebo-controlled study. After tracheal intubation, group I received i.v. dexamethasone 5 mg, whereas groups II and III received i.v. metoclopramide 10 mg and saline, respectively. RESULTS: Patients in group I reported a lower incidence of PONV and requested less rescue antiemetics than those in group III during the first four postoperative hours (P <0.01). Patients in group I reported a lower incidence of PONV than those in groups II (P <0.05) and III (P <0.01) during the 24-hr postoperative period. Groups II and III did not differ from each other in the incidence of PONV and the proportion of patients who requested rescue antiemetics. CONCLUSION: Prophylactic iv dexamethasone 5 mg significantly reduces the incidence of PONV in women undergoing ambulatory laparoscopic tubal ligation. At this dose, dexamethasone is more effective than metoclopramide 10 mg or placebo.

Adult↗
PubMed2001

Characterization of collagen gel solutions and collagen matrices for cell culture.

The influence of glutaraldehyde as a crosslinking agent to increase the strength of collagen matrices for cell culture was examined in this study. Collagen solutions of 1% were treated with different concentrations (0-0.2%) of glutaraldehyde for 24 h. The viscoelasticity of the resulting collagen gel solution was measured using dynamic mechanical analysis (DMA), which demonstrated that all collagen gel solutions examined followed the same model pattern. The creep compliance model of Voigt-Kelvin satisfactorily described the change of viscoelasticity expressed by these collagen gel solutions. These crosslinked collagen gel solutions were freeze-dried to form a matrix with a thickness of about 0.2-0.3 mm. The break modulus of these collagen matrices measured by DMA revealed that the higher the degree of crosslinking. the higher the break modulus. The compatibility of fibroblasts isolated from nude mouse skin with these collagen matrices was found to be acceptable at a cell density of 3 x 10(5) cells/cm2 with no contraction, even when using a concentration of glutaraldehyde of up to 0.2%.

Animals↗
PubMed2000

Effect of beta-cyclodextrin on pasting properties of wheat starch.

Changes of viscosity characteristics of genetically diverse hexaploid wheat starches during pasting in water, 1% NaCl solution, or at pH 4 or pH 10 were studied using a Rapid Visco-Analyzer. Peak viscosity (PV), hot paste viscosity (HPV) and cool paste viscosity (CPV) of all the wheat starches was little affected in pH 4 and pH 10 treatments. In 1% NaCl, all starches showed substantial increases in all three parameters relative to pasting in water. The use of 1% beta-cyclodextrin (beta-CD) (cycloheptaamylose) solution increased PV of high-swelling starches, but generally slightly decreased that of low swelling starches in all treatment conditions. HPV was always reduced by addition of 1% beta-CD, but CPV was increased in most treatments for Anza and Yecora Rojo (low swelling), but decreased for Klasic (high swelling). Bacterial alpha-amylase was added to starch or flour. The effect of beta-CD was shown to be independent of alpha-amylase inhibition in wheat starch, but beta-CD strongly inhibited alpha-amylase in wheat flour.

Cyclodextrins↗
PubMed2000

Vascular endothelial growth factor and interleukin-6 in peritoneal fluid of women with endometriosis.

OBJECTIVE(S): To determine [1] vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) levels in peritoneal fluid from women with endometriosis and compare them with those from oral contraceptive (OC) users and normal cycling women and [2] any correlation between VEGF and IL-6 concentrations. DESIGN: Controlled clinical study. SETTING: University medical center. PATIENT(S): Patients undergoing laparoscopy for infertility or other benign gynecologic conditions. INTERVENTION(S): Peritoneal fluid samples were collected. MAIN OUTCOME MEASURE(S): Levels of VEGF and IL-6 in peritoneal fluid were determined. RESULT(S): Compared with normal controls or women with less severe endometriosis (implant scores of 5 or less), women with more advanced endometriosis (implant scores of 6 or more) have elevated VEGF and IL-6 levels in peritoneal fluid. Compared with normal controls, markedly suppressed IL-6 but similar VEGF levels were found in peritoneal fluid from OC users. Neither VEGF nor IL-6 varied cyclically in normal women or those with endometriosis. There was no correlation between levels of VEGF and IL-6 in peritoneal fluid. There was no correlation between implant scores and VEGF or IL-6 levels. CONCLUSION: The inflammation associated with endometriosis, through increased levels of peritoneal fluid VEGF, may promote angiogenesis for the progressive growth of endometriosis. Effective treatment of endometriosis by combination estrogen-progestin pills may involve the suppression of such inflammatory responses.

Ascitic Fluid↗
PubMed2000

Oxygen deficit determinations for a major river in eastern Hong Kong, China.

Determination of oxygen deficit in the Hong Kong Shing-Mun River was based on the oxygen uptake by water, algal respiration and river sediment and the oxygen supplied to the river by surface reaeration and algal photosynthesis. A systematic study was conducted to examine the effect of water temperature, flow velocity and water depth on both the oxygen demands and the oxygen supplies. The oxygen budget of a water column in a selected section of the river was modeled. The results of the oxygen budget analysis showed that when water temperature was around 10 degrees C (the lowest temperature in the river), no deficit was observed. When water temperature was 10 degrees C to 20 degrees C, a small oxygen deficit appeared, especially in the deeper water. At the highest water temperature (30 degrees C), the oxygen deficit was maximal, -6.84 g O2/m2/day, in the night-time during the Spring tide period.

Environmental Monitoring↗
PubMed2000

A pollen-specific and desiccation-associated transcript in Lilium longiflorum during development and stress.

A cDNA clone encoding a desiccation-induced protein (LLA23) has been isolated from the mature pollen of a Lilium longiflorum cDNA library. Sequence analysis revealed significant similarity between the predicted LLA23 polypeptide, particularly at the C-terminal half of the sequence and a group of water-deficit/ripening-induced proteins. The expression of LLA23 gene is pollen-specific and the transcript accumulates only at the later stage of pollen maturation prior to anthesis. Premature drying of developing pollen confirmed that the accumulation of LLA23 transcripts was associated with desiccation. The LLA23 proteins decreased their levels when pollen/pollen tubes grew in the germination buffer. Treatments of pollen with abscisic acid (ABA) and polyethylene glycol (PEG)-8000 during germination greatly retarded the disappearance of LLA23 proteins and mRNAs. The LLA23 transcripts decreased their levels in pollen tubes grown both in vitro and in vivo, but the disappearance of LLA23 transcripts in tube cells grown in vivo was slower than those grown in vitro. In situ localization using anti-chicken immunoglobulin G conjugated with gold particles confirmed that LLA23 was located in the cytoplasm of pollen grains. The protective function of the desiccation-related proteins in the cytoplasm of pollen grains is proposed.

Amino Acid Sequence↗
PubMed2000

Evaluation of an innovative plastic cube phantom designed to improve the efficiency of accelerator QA.

A new cubic phantom was designed to improve the efficiency on the QA measurement of accelerator. It has a variety of applications, such as dose constancy check, depth dose verifications, and symmetry and flatness evaluations. In particular, this new design makes it much easier to perform the check on output constancy vs. gantry angles as a cylindrical ion chamber positioned at the center of the phantom. The reproducibility of the setup using this phantom has been investigated. The charge effect of the phantom is found to be insignificant. It also reduces the monthly dosimetric QA time spent on a typical multimodality accelerator by approximately 40%.

Electrons↗
PubMed2000

Ginseng flowers stimulate progesterone production from bovine luteal cells.

Our previous report first showed evidence that polysaccharides isolated from ginseng leaves obtained from Jilin, China possess luteotropic activities. In this study, we made further investigations on the root and flowers of Korean ginseng by means of the same bioassay system described briefly as follows. Frozen-thawed bovine luteal cells (1 x 10(5) cells/ml/well) in M199 were incubated in 24-well culture plates at 37 degrees C in a 5 % CO2 incubator. Ten microl of tested drugs with 1, 10 and 100 microg/ml were added into each well. After 4- and 24-hr incubation, the media were harvested and assayed for progesterone by an enzyme immunoassay. The production of progesterone from cells is the indicator for evaluating the action of tested drugs. Results showed that hot water extracts ofginseng flowers (GF-1) with 10 to 100 microg/ml significantly increased progesterone production, whereas those from ginseng root (GR-1) could not. Crude polysaccharides (GF-2) isolated from GF-1 is the active component and the small molecules (mw < 10,000 dalton) are excluded, indicating that the ginseng root has no luteotropic activities, but the polysaccharides of ginseng flowers have.

Animals↗
PubMed2000

Regulation of vascular endothelial growth factor expression by estrogens and progestins.

Estrogens increase the expression of vascular endothelial growth factor (VEGF) mRNA in the rodent uterus. This regulatory effect is rapid, beginning within 1 hr after hormone treatment, dose dependent, and blocked by the pure antiestrogen ICI 182,780. The induction of the transcript is blocked by inhibitors of RNA but not of protein synthesis, and we have recently identified estrogen response elements in the VEGF gene. Collectively, these findings indicate that estrogens regulate uterine VEGF expression at the transcriptional level via the classical nuclear estrogen receptor pathway. Estrogen induction of VEGF occurs in the stromal layer of the rodent uterus, and estradiol induces expression of VEGF transcript levels in cultured human uterine stromal cells. Progestins also induce VEGF expression in the rodent uterus, although the effect is less marked and slower in onset than estrogenic effects. The effect of progestins is blocked by the antiprogestin mifepristone (RU-486), suggesting that it is also mediated by a classical nuclear receptor pathway. In addition, progestins regulate expression of VEGF mRNA and protein in cultured human T47-D breast cancer cells. The development of uterine leiomyomas is associated with exposure to ovarian sex steroids, abnormal uterine bleeding is commonly seen in patients with leiomyomas, and fibroids require an increased vascular supply for their growth. These observations suggest that VEGF and other angiogenic factors may represent potential targets for the treatment and prevention of uterine fibroids.

Breast Neoplasms↗
PubMed2000

Morphologic preservation and variability of human donor retina.

PURPOSE: To facilitate studies of human retina and utilization of human retinal tissue for treatment of retinal diseases, we studied morphologic preservation in postmortem human retina. METHODS: Morphology of retinas from thirty-one human eyes was examined using light and electron microscopy. The inner and outer retina, rod and cone photoreceptor cells, and central and peripheral retina were compared with regard to morphologic preservation. Possible factors affecting survival were analyzed. RESULTS: The earliest postmortem change was vacuolation of the nerve fiber layer within a few hours postmortem, followed by vacuolation and cytoplasmic swelling of the inner retina. As compared with the inner retina, outer retinal structure was better preserved, i.e., the photoreceptor cells maintained better morphology. Rod cell morphology was better preserved than cone cell morphology, with good preservation of the rod outer segment disc membranes and the inner segment mitochondrial membranes. Thus, well-preserved rod photoreceptor cells were evident in specimens at least 48-hours postmortem. Peripheral retina was better preserved than the central retina including the fovea and perifovea. Factors affecting anatomical integrity included the total time postmortem and, more importantly, the time between death and enucleation. Other factors, including age and sex, did not appear to affect morphological preservation in the present study. CONCLUSIONS: Human retina postmortem remained morphologically intact for a relatively long period of time, with differential preservation among different geographic areas and cell types. This morphologic evidence is consistent with previous findings of functional preservation (e.g. , photoresponses) in such tissue. This study may shed some light on understanding of human retina and its utilization for retinal transplantation.

Adolescent↗
PubMed1999

Characterization of two subclasses of PR-10 transcripts in lily anthers and induction of their genes through separate signal transduction pathways.

The lily PR-10 belongs to a family of intracellular pathogenesis-related (IPR) proteins. Genomic Southern analysis indicates that the PR-10 is encoded by a family of multiple genes. Seven heterogeneous cDNA clones encoding lily PR-10 from Lilium longiflorum are divided into two subclasses based on sequence comparison and Southern hybridization. A 82% overall sequence similarity was found between the two subclasses (represented by PR-10c and d). The two cDNAs include an open reading frame of 474 bp encoding 157 amino acids. 5'- and 3'-untranslated regions exhibit low similarity, but similarity is high in the coding region. The lily PR-10 genes are induced by abscisic acid (ABA) and methyl jasmonate (MeJA) in the anther and various other organs of lily plants. The induction of PR-10 genes by ABA and MeJA in lily anthers occurs by two separate signal transduction pathways. The protein phosphatase inhibitor okadaic acid inhibits the MeJA-induced expression of PR-10 genes downstream of MeJA. In addition, the protein kinase inhibitor staurosporine inhibits the MeJA-induced expression of PR-10 genes, implying that an activity of staurosporine-sensitive protein kinases exists downstream of MeJA in the anther. However, okadaic acid does not inhibit the ABA-induced expression of PR-10 genes whereas staurosporine does. These observations suggest that, in addition to the known pathway that ABA induces gene expression by activating JA or MeJA, a MeJA-independent pathway of ABA induction exists in the anther. The alternative pathway of ABA induction involves a staurosporine-sensitive protein kinase activity downstream of ABA.

Abscisic Acid↗
PubMed1999

CD5- small B-cell leukemias are rarely classifiable as chronic lymphocytic leukemia.

Expression of the CD5 antigen by neoplastic cells often is considered a diagnostic criterion for B-cell chronic lymphocytic leukemia (B-CLL). However, published series frequently include a number of CD5- cases. We studied the spectrum of CD5- B-cell lymphoproliferative disorders presenting with leukemia involvement and reassessed the prevalence of CD5- B-CLL. We immunophenotyped 192 cases of clonal, small lymphocytic, B-cell disorders involving peripheral blood or bone marrow. Of these, 41 CD5- cases were further analyzed, correlating the immunophenotypic findings with pathologic material and clinical data. Only 3 CD5- cases were classified as CD5- B-CLL. These 3 cases had features unusual for B-CLL, including bright surface immunoglobulin expression, bright CD20 expression, and absence of CD23 expression (2 cases) or Richter syndrome (1 case). The remainder of the CD5- cases consisted of hairy cell leukemia, hairy cell variant, prolymphocytic leukemia, follicular center cell lymphoma, lymphoplasmacytic lymphoma, splenic marginal zone lymphoma (SMZL), small lymphocytic lymphoma with marrow fibrosis, and lymphoma, not further classified. Eight cases remained unclassified, but some displayed features of SMZL. CD5- lymphoproliferative disorders of peripheral blood or bone marrow are unlikely to be CLL and often are classified more appropriately as non-Hodgkin lymphoma in the leukemia phase.

Adult↗
PubMed1998

Repetitive transcranial magnetic stimulation activates specific regions in rat brain.

Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive technique to induce electric currents in the brain. Although rTMS is being evaluated as a possible alternative to electroconvulsive therapy for the treatment of refractory depression, little is known about the pattern of activation induced in the brain by rTMS. We have compared immediate early gene expression in rat brain after rTMS and electroconvulsive stimulation, a well-established animal model for electroconvulsive therapy. Our result shows that rTMS applied in conditions effective in animal models of depression induces different patterns of immediate-early gene expression than does electroconvulsive stimulation. In particular, rTMS evokes strong neural responses in the paraventricular nucleus of the thalamus (PVT) and in other regions involved in the regulation of circadian rhythms. The response in PVT is independent of the orientation of the stimulation probe relative to the head. Part of this response is likely because of direct activation, as repetitive magnetic stimulation also activates PVT neurons in brain slices.

Animals↗
PubMed1998

Specific agrin isoforms induce cAMP response element binding protein phosphorylation in hippocampal neurons.

The synaptic basal lamina protein agrin is essential for the formation of neuromuscular junctions. Agrin mediates the postsynaptic clustering of acetylcholine receptors and regulates transcription in muscles. Agrin expression is not restricted to motor neurons but can be demonstrated throughout the CNS. The functional significance of agrin expression in neurons other than motor neurons is unknown. To test whether agrin triggers responses in neurons that lead to the activation of transcription factors, we have analyzed phosphorylation of the transcriptional regulatory site serine 133 of the transcription factor CREB (cAMP response element binding protein) in primary hippocampal neurons. Our results indicate that the neuronal (Ag4,8), but not the non-neuronal (Ag0,0), isoform of agrin induces CREB phosphorylation in hippocampal neurons. The kinetics of agrin- and BDNF-induced CREB phosphorylation are similar: peak levels are reached in minutes and are strongly reduced 2 hr later. Neuronal responses to agrin require extracellular calcium, and, in contrast to tyrosine kinase inhibitors, the specific inhibition of protein kinase A (PKA) does not affect agrin-evoked CREB phosphorylation. Our results show that hippocampal neurons specifically respond to neuronal agrin in a Ca2+-dependent manner and via the activation of tyrosine kinases.

Agrin↗