Biomedical subjects

C Huang

Publications and source records attributed to C Huang.

At least 253 records · Page 14Linked to original sources

PubMed1998

The Role of Ionic Surfactants in Compression Dewatering of Alum Sludge.

This work has experimentally investigated the characteristics of filtration followed by consolidation dewatering of an alum sludge, with especial attention to the effects of adding ionic surfactants (SDS or CTAB). The filtration and consolidation stages at a pressure of 3000 psi were discussed separately. The efficiency of filtration is enhanced in the presence of surfactant molecules; however, the cationic surfactant (CTAB) raises the consolidation rate while the anionic surfactant (SDS) retards it. A newly proposed rheological model has been employed for interpreting the consolidation data. CTAB would not alter markedly the moisture distribution in the sludge, but SDS does increase markedly the amount of the tightly bound moisture by diminishing the portion occupied by pore water. The possible role of surfactants in the sludge flocs is considered. Both surfactants can be used as conditioning aids during the filtration stage. However, the applications of SDS to the consolidation stage are not encouraged. Copyright 1998 Academic Press.

Journal Article↗

PubMed1998

Serotonin-mediated production of interstitial collagenase by uterine smooth muscle cells requires interleukin-1alpha, but not interleukin-1beta.

The activation of the gene for interstitial collagenase in myometrial smooth muscle cells is absolutely dependent upon the presence of serotonin. Our previous studies investigating the mechanisms of this induction demonstrated that the mRNAs of both interleukin-1 (IL-1) isoforms, IL-1alpha and IL-1beta, are induced by serotonin and that the induction of IL-1 is required for the subsequent induction of collagenase. These data provided compelling evidence that serotonin-induced IL-1 acts via an autocrine loop in activating the collagenase gene. The experiments described here were designed to examine the potential role of each IL-1 isoform in collagenase production by using neutralizing antisera specific to each isoform of the cytokine. The antisera were examined for their ability to inhibit the serotonin-dependent production of the mRNA for collagenase and of the cytokines themselves. Neutralizing antiserum against IL-1alpha, but not against IL-1beta, inhibited the induction of the mRNA for collagenase and of the mRNAs for both IL-1alpha and IL-1beta. Western analysis indicated that detectable levels of IL-1alpha protein, but not that of IL-1beta, are produced at the time of serotonin-dependent collagenase induction. In contrast, significant levels of IL-1beta protein are detected only when bacterial lipopolysaccharide is added to the cells. Taken together, the results of our study indicate that IL-1alpha, but not IL-1beta, plays an obligatory role in multiple serotonin-mediated gene regulations in the myometrial smooth muscle cell. In addition, the data suggest that IL-1beta production has the potential for modifying myometrial function in pathological settings, particularly that of uterine infection.

Animals↗

PubMed1998

Essential role of p53 in phenethyl isothiocyanate-induced apoptosis.

Phenethyl isothiocyanate (PEITC) is a natural product that is among the most effective cancer chemopreventive agents known. Mechanistic studies indicate that the chemopreventive activity of PEITC is associated with its favorable modification of carcinogen metabolism and its induction of apoptosis. Here, we found that PEITC blocks tumor promoter (12-O-tetradecanoylphorbol-13-acetate or epidermal growth factor)-induced cell transformation in mouse epidermal JB6 cells, and this inhibitory activity on cell transformation is correlated with induction of apoptosis. Most importantly, apoptosis induction by PEITC occurs through a p53-dependent pathway. This was demonstrated not only by results that PEITC induction of p53 protein expression and p53-dependent transactivation but also by PEITC-induced apoptosis in p53 +/+ cells but not in p53 -/- cells. In contrast, PEITC induced apoptosis in cells with both normal or deficient sphingomyelinase activity. Our results demonstrate for the first time that p53 elevation is required for PEITC-induced apoptosis, which may be involved in its cancer chemopreventive activity.

Animals↗

PubMed1998

Thyroid hormone regulates the acetyl-CoA carboxylase PI promoter.

The acetyl-CoA carboxylase-alpha gene has two promoters, PI and PII. A variety of mRNA products result from this gene, depending on promoter usage and splicing events. We have investigated thyroid hormone regulation of acetyl-CoA carboxylase-alpha gene expression, using the reverse-transcription polymerase chain reaction with PI- or PII-specific primers. RNA was extracted from a range of tissues taken from hypo-, eu-, or hyperthyroid rats. PII-generated products were found in all tissues examined at similar levels and were not affected by thyroid state. Products derived from PI were also widely found but with more variable levels of expression. PI mRNAs were reduced in hypo- and elevated in hyperthyroid livers. In brown adipose tissue, more PI products were found in hypothyroid animals. Thus, thyroid hormone regulates the activity of the acetyl-CoA carboxylase PI promoter to influence fatty acid synthesis in a tissue-specific manner.

Acetyl-CoA Carboxylase↗

PubMed1998

A unifying Tm diagram for phosphatidylethanolamines with sn-1 C20 saturated and sn-2 C18 unsaturated acyl chains.

We have determined calorimetrically the phase transition temperature (Tm) values of five sn-1 saturated/sn-2 unsaturated phosphatidylethanolamines (PE) in which the sn-1 acyl chain has 20 carbons and the sn-2 acyl chain has 18 carbons with different number and position of the cis double bond. When these Tm values are combined with the five published Tm values of related unsaturated PE, a unifying Tm diagram is generated for the first time. Moreover, as the molecular mechanics simulated structures of these lipids are taken into consideration, this unifying Tm diagram provides insight into how variations in the number and position of the cis double bond in the lipid's sn-2 acyl chain can influence the phase transition behavior of the lipid bilayer.

Calorimetry, Differential Scanning↗

PubMed1998

Age-related loss of immunoregulatory function in peripheral blood CD8 T cells.

CD8+ T cells from young individuals become inhibitory for the (Staphylococcus aureus + interleukin 2)-induced differentiation of autologous B cells into immunoglobulin secreting cells (ISC) after exposure to pokeweed mitogen (PWM), dimaprit or intracellular cAMP raising agents, such as forskolin or dibutyryl-cAMP. In the present study this immunoregulatory activity was found to be lacking in CD8+ T cells from peripheral blood lymphocytes (PBL) of aged (> 67 years old) subjects. Splenic CD8+ T cells from most individuals examined, including some aged subjects, exhibited this activity. While an age-related decrease in the CD8+ T cell subset, primarily in the virgin CD8+ T cells in PBL, was detected, this decrease was not sufficient to explain a total absence of activity. There was no age-related decrease in cAMP upregulation by forskolin or dimaprit in peripheral blood T cells. However, whereas PWM induced a highly significant increase in mRNA for transforming growth factor-beta (TGF-beta) in T cells from young individuals, no such increase could be detected in T cells from aged subjects. It is suggested that the decrease in immunoregulatory activity in PBL from the elderly may at least in part be due to a decrease in TGF-beta production.

Adult↗

PubMed1998

Mutations in exon 7 and 8 of p53 as poor prognostic factors in patients with non-small cell lung cancer.

This study was performed to clarify the different effects of each mutant exon of p53 as indicators of a poor prognosis in patients with non-small cell lung cancer (NSCLC). Tumor tissues of 204 patients with NSCLC were analysed; 96 tumors were stage I, 22 stage II, and 86 stage III. DNA was extracted from frozen specimens and polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and direct sequencing were performed to investigate mutations of p53 from exon 5 to exon 8. Seventy-five patients with NSCLC (36.8%) had mutations in p53 which included 72 cases of missense mutations and three cases of non-missense mutations. The overall survival rate of patients with mutant p53 adenocarcinomas was strikingly worse than that of patients whose tumors had wild-type p53 (35.7% vs 53.8%; P=0.041), but no significant difference in survival was found in the patients with NSCLC and squamous cell carcinoma. Mutations in exon 5 of p53 occurred in 33 cases (16.2%), mutation in exon 6 was detected in only one case (0.5%), mutations in exon 7 in 20 cases (9.8%), and mutations in exon 8 in 18 cases (8.8%). The overall survival rate of patients with mutations in exon 7 was worse than that of patients with wild-type p53 in NSCLCs and adenocarcinomas (42.9% vs 56.0%; P=0.025 and 33.3% vs 53.8%; P=0.048, respectively), whereas the overall survival of patients with mutations in exon 5 was almost the same as that of patients with wild-type p53. In addition, the overall survival rate of patients with mutations in exon 8 was strikingly worse than that of patients with wild-type p53 in NSCLCs, adenocarcinomas and squamous cell carcinomas (22.9% vs 56.0%; P<0.001, 19.0% vs 53.8%; P=0.004 and 33.3% vs 62.5%; P=0.042, respectively). Multivariate analysis with the Cox regression model of patients with NSCLC, adenocarcinoma and squamous cell carcinoma indicated that mutations in exon 8 were best correlated with the overall survival rate, followed by lymph node status (P<0.001, P=0.015 and P=0.006, respectively), and mutations in exon 7 of NSCLC were also revealed to have good correlation, followed by lymph node status and mutations in exon 8 (P=0.031). Mutation of p53 was a poor prognostic factor for adenocarcinoma as described previously. Moreover, mutations in exon 8 were more useful indicators of prognosis not only for adenocarcinoma but also for NSCLC. Worse overall survival of the patients with mutations in exon 8 of p53 was suggested to be associated with codon 273 mutations as well as mutations between codon 280 and 285 included into the H2 alpha helix corresponding to residues 278-286. These results suggested that abnormal conformation of H2 alpha helix might play an important role not only in the loss of normal function but also in the acquisition of tumorigenesis. Investigation of mutations in exon 8, especially codon 273 mutation and mutant H2 alpha helix was considered to be a clinically useful approach for determining the prognosis of patients with NSCLC.

Adenocarcinoma↗

PubMed1998

Serotonin regulates the expression of the gene for alpha2-macroglobulin in myometrial smooth muscle cells.

Serotonin (5-hydroxytryptamine (5-MT)) has been shown to be a regulator of gene expression in rat myometrial smooth muscle cells (SMC). Serotonin activates the genes for interstitial collagenase, interleukin-1alpha, -1beta and interleukin-6, among others. On the other hand, serotonin down-regulates the genes for types I and III collagen and fibronectin. Here we show that serotonin is also a negative regulator of the expression of anti-protease alpha2-macroglobulin (alpha2M) in SMC. The serotonin-dependent repression occurs at both the mRNA and protein levels, and is mediated by the 5-HT2A receptor subtype. The inhibitory effect is prevented by cycloheximide, indicating the requirement for the synthesis of one or more proteins. Interleukin-1 (IL-1), which is induced by serotonin in SMC and is required for subsequent interstitial collagenase induction, appears not to be one of these intermediates. On the other hand, progesterone, the major steroid hormone of pregnancy, is capable of reversing the serotonin-mediated inhibition of alpha2M. The phorbol myristate acetate (PMA), which mimics the induction of interstitial collagenase by serotonin, fails to affect the inhibition of alpha2M production. The cell-permeable cyclic AMP analogue 8-bromoadenosine 3':5'-cyclic monophosphate sodium salt (8-bromo-cAMP), is, however, capable of fully reproducing the action of serotonin on alpha2M. These results further speak to the ability of serotonin to regulate gene expression in the myometrial SMC, both positively and negatively. In addition, although all the effects of serotonin so far identified are mediated by the 5-HT2A receptor, different post-receptor pathways appear to mediate the positively and negatively regulated genes.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed1998

Application of ion chromatography to the semiconductor industry. I. Measurement of acidic airborne contaminants in cleanrooms.

The purpose of this study is to establish an analytical method for the simultaneous measurement of various acidic airborne contaminants in class 1 cleanrooms of a semiconductor fabrication facility (Fab). Acidic contaminants in air samples were adsorbed on silica gel tubes, extracted with carbonate-hydrogencarbonate solutions, and analyzed by ion chromatography. The recovery of HF was 100% and that of HCl was 91 approximately 100%. The method shows high resolution and sensitivity, and is capable for air analysis in the class 1 cleanroom. Different locations inside the cleanroom show deviations in the contaminant levels, indicating that the air quality is not the same throughout the cleanroom. The wet chemical station shows higher levels of contaminant concentrations than the other two areas. Each location also shows day-to-day variation.

Acids↗

PubMed1998

Induction of a selective and persistent extravasation of neutrophils into the peritoneal cavity by tryptase mouse mast cell protease 6.

Recombinant mouse mast cell protease 6 (mMCP-6) was generated to study the role of this tryptase in inflammatory reactions. Seven to forty-eight hours after the i.p. injection of recombinant mMCP-6 into BALB/c, mast cell-deficient WCB6F1-Sl/Sl(d), C5-deficient, or mMCP-5-null mice, the number of neutrophils in the peritoneal cavity of each animal increased significantly by >50-fold. The failure of the closely related recombinant tryptase mMCP-7 to induce a comparable peritonitis indicates that the substrate specificities of the two tryptases are very different. Unlike most forms of acute inflammation, the mMCP-6-mediated peritonitis was relatively long lasting and neutrophil specific. Mouse MCP-6 did not induce neutrophil chemotaxis directly in an in vitro assay, but did promote chemotaxis of the leukocyte in the presence of endothelial cells. Mouse MCP-6 did not induce cultured human endothelial cells to express TNF-alpha, RANTES, IL-1alpha, or IL-6. However, the tryptase induced endothelial cells to express large amounts of IL-8 continually over a 40-h period. Neither enzymatically active mMCP-7 nor enzymatically inactive pro-mMCP-6 was able to induce endothelial cells to increase their expression of IL-8. Although the mechanism by which mMCP-6 induces neutrophil accumulation in tissues remains to be determined, the finding that mMCP-6 induces cultured human endothelial cells to selectively release large amounts of IL-8 raises the possibility that this tryptase regulates the steady state levels of neutrophil-specific chemokines in vivo during mast cell-mediated inflammatory events.

Animals↗

PubMed1998

Inhibitory effects of perillyl alcohol on UVB-induced murine skin cancer and AP-1 transactivation.

The monoterpene perillyl alcohol (POH) has proven efficacious against the formation and progression of a variety of cancers. In this study, we tested the ability of POH to inhibit photocarcinogenesis in a nonmelanoma model of mouse skin carcinogenesis and its ability to inhibit UVB-induced activator protein 1 (AP-1) transactivation in mouse skin and human keratinocytes. POH (10 mM) was applied topically to the ears and shaved dorsal surface of groups of 35 BALB/c mice throughout the experiment, during and after UVB treatment. Topical POH significantly inhibited tumor incidence and multiplicity, average tumor size, and the average tumor burden/mouse without any apparent toxicity. POH inhibited UVB-induced AP-1 transactivation in both cultured human keratinocytes and transgenic mice that stably express a luciferase reporter driven by AP-1 elements. The results suggest that POH might be used for chemoprevention of human skin cancer, and that inhibition of AP-1 activity is functionally related to inhibition of skin carcinogenesis.

Administration, Topical↗

PubMed1998

Expression and purification of enzymatically active recombinant granzyme B in a baculovirus system.

Granzyme B (GranB), a serine protease stored in the granules of cytotoxic T lymphocytes and natural killer cells, can initiate target cell apoptosis. To produce large amounts of purified active enzyme, recombinant murine granzyme B (rGranB) was expressed from baculovirus in insect cells. The expressed rGranB is secreted into the culture medium and can be readily purified to homogeneity by one-step affinity chromatography to yield 1.5 mg enzyme per liter insect cell medium. RGranB is recognized by a GranB-specific anti-peptide antibody and is active against synthetic substrate Boc-Ala-Ala-Asp-SBzl with kinetic constant (kcat/Km 45,000 M-1s-1) comparable to purified human GranB, RGranB processes the caspase pro-CPP32 into its enzymatically active form and induces DNA fragmentation in isolated nuclei in the presence of cytosolic factors. The ability to express enzymatically active rGranB using the baculovirus system will help elucidate the role of this granzyme in the immune response.

Animals↗

PubMed1998

Shortage of mitogen-activated protein kinase is responsible for resistance to AP-1 transactivation and transformation in mouse JB6 cells.

The JB6 mouse epidermal cell system, which includes tumor promotion-sensitive (P+) and tumor promotion-resistant (P-) cells, is a well-established and extensively used cell culture model for studying the mechanism of late-stage tumor promotion. Tumor promoters, such as 12-O-tetradecanoylphorbol 13-acetate (TPA) or epidermal growth factor (EGF), induce high levels of activator protein 1 (AP-1) activity and large, tumorigenic, anchorage-independent colonies in soft agar at a high frequency in JB6 P+ cells, but not in JB6 P- cells. We report here a molecular explanation for the defect in the AP-1 activation and promotion-resistant phenotype of P- cells. We demonstrate that the lack of AP-1 activation and cell transformation responses to TPA and EGF in P- cells appears attributable to the low level of mitogen-activated protein kinase (MAPK) (extracellular signal-regulated protein kinase, Erk) in these cells. TPA and EGF induce transactivation of AP-1 activity in P+ cells but not in P- cells. Nonphosphorylated forms and TPA- or EGF-induced phosphorylated forms of Erks (Erk1 and Erk2) in P- cells were much lower than those in P+ cells. Stable transfection of wild-type MAPK (Erk2) into P- cells restored its response to TPA and EGF for both AP-1 activation and cell transformation. These results suggest that the shortage of MAPK (Erk1 and Erk2) appears to be an important contributor to the tumor promotion-resistant phenotype in JB6 cells.

Animals↗

PubMed1998

Purification and properties of soman-hydrolyzing enzyme from human liver.

A soman-hydrolyzing enzyme (somanase) was purified from human liver. The human somanase is capable of hydrolyzing pinacolyl methylphosphonofluoridate (soman), diisopropylphosphorofluoridate (DFP), and ethyl-N-dimethyl phosphoramidocyanidate (Tabun) with P-F or P-CN bonding, but not ethyl (S-2-diisopropylaminoethyl) methylphosphonothiolate (VX) and diethyl-p-nitro-phosphenylphosphate (paraoxon) with P-S or P-O bonding. The somanase has been purified 1570-fold with a specific activity of 41.4 mumol/min/mg protein. Its molecular weight is around 58 kDa determined by SDS-PAGE. The somanase could be stimulated by the divalent cations Mn+2, Mg+2, and Co+2, where CO+2 activation is the highest. The requirement of disulfide bonds for the enzyme activity was demonstrated by the inhibition effect of DTT.

Catalysis↗

PubMed1998

Expression of the antioxidant gene NKEF in the central nervous system.

Free radicals and the oxidative stress they impose can cause serious injury in the nervous system and contribute to pathology associated with a wide variety of degenerative and traumatic disorders. In this study, we examined the expression of an antioxidant defense gene, nkef, in human tissue and isolated populations of rat brain cells using Western and Northern blot analysis. NKEF protein was expressed in human brain, liver, kidney, muscle, and lung. The human endothelial cell line ECV expressed a 25-kDa band in addition to the 22-kDa band normally observed. In the central nervous system, a 22-kDa NKEF band was present in cortical gray and white matter, hippocampus, cerebellum, and spinal cord in roughly similar amounts. Expression of NKEF-A and NKEF-B subtypes was evaluated by Northern analysis of cultured cell types from embryonic rat brain. Astrocyte and microglia expressed both 22- and 25-kDa bands, whereas cortical neurons and oligodendrocytes contained only the 22-kDa protein band. Northern blot analysis of these cell types revealed low levels of NKEF-A message in neurons and oligodendrocytes, and relatively low levels of NKEF-B in microglia. Differential expression of these antioxidant defense genes may contribute to the selective vulnerability of brain cell types to specific kinds of oxidative stress.

Animals↗

PubMed1998

Isolation and characterization of desulfovibrio senezii sp. nov., A halotolerant sulfate reducer from a solar saltern and phylogenetic confirmation of desulfovibrio fructosovorans as a new species

A new halotolerant Desulfovibrio, strain CVLT (T = type strain), was isolated from a solar saltern in California. The curved, gram-negative, nonsporeforming cells (0.3 x 1.0-1.3 &mgr;m) occurred singly, in pairs, or in chains, were motile by a single polar flagellum and tolerated up to 12.5% NaCl. Strain CVLT had a generation time of 60 min when grown in lactate-yeast extract medium under optimal conditions (37 degreesC, pH 7.6, 2.5% NaCl). It used lactate, pyruvate, cysteine, or H2/CO2 + acetate as electron donors, and sulfate, sulfite, thiosulfate, or fumarate as electron acceptors. Elemental sulfur, nitrate, or oxygen were not used. Sulfite and thiosulfate were disproportionated to sulfate and sulfide. The G+C content of the DNA was 62 mol%. Phylogenetic analysis revealed that Desulfovibrio fructosovorans was the nearest relative. Strain CVLT is clearly different from other Desulfovibrio species, and is designated Desulfovibrio senezii sp. nov. (DSM 8436).

Journal Article↗

PubMed1998

Prediction of fracture risk by radiographic absorptiometry and quantitative ultrasound: a prospective study.

Recent developments in computer-assisted radiographic absorptiometry (RA) and quantitative ultrasound techniques (QUS) provide readily accessible and relatively inexpensive methods for assessing bone mineral status. However, few population-based studies have investigated the ability of RA and ultrasound to predict fracture risk prospectively. We explored the ability of RA and QUS to predict fracture risk among 560 postmenopausal women from the Hawaii Osteoporosis Study; average follow-up was 2.7 years. An incident vertebral fracture was defined as a decrease of more than 15% in vertebral heights on subsequent films. Self-reported nonspine fractures were verified by medical records. The prospective associations of vertebral fractures, nonspine fractures, and any (spine or nonspine) fractures with bone measurements were examined using logistic regression, adjusting for age. Both phalangeal bone mineral density (BMD) and metacarpal BMD, measured using RA, predicted future fracture risk. The age-adjusted odds ratios (corresponding to 1 SD decrease in BMD) for vertebral fractures, nonspine fractures, and any fractures were 3.41, 1.50, and 1.91, respectively, for phalangeal BMD, and 1.71, 1.49, 1.55, respectively for metacarpal BMD. Calcaneal broadband ultrasound attenuation (BUA) also showed significant association with fracture risk, with age-adjusted odds ratios of 1.50, 1.89, and 1.72 for vertebral fractures, nonspine fractures, and any fractures, respectively. We conclude that hand RA and calcaneal BUA are significant predictors of nonspine fracture, vertebral fracture, and overall fracture risk. The attractive features of these techniques, such as portability, relatively low cost, and ease of use, make them promising alternatives to conventional bone measurement techniques used for the assessment of fracture risk.

Absorptiometry, Photon↗

PubMed1998

Bilateral testicular tumors in an infant.

A 7-month-old infant showed bilateral enlarged, nontender scrotal masses. The level of alpha-fetoprotein was greater than 10,000 ng/ml preoperatively; a high left inguinal orchiectomy was performed for a suspected yolk-sac tumor. The right testis was diagnosed as a mature teratoma because it was not possible to establish a line of cleavage between the tumor and the normal tissue, and a high right inguinal orchiectomy was performed. Only one case of bilateral testicular teratomas has been reported in the literature to date. We report a rare second case of bilateral testicular tumors, one a yolk-sac tumor and the other a teratoma.

Endodermal Sinus Tumor↗