Biomedical subjects

H Huang

Publications and source records attributed to H Huang.

At least 163 records · Page 9Linked to original sources

PubMed2001

[The adenovirus-mediated HSV-TK/GCV suicide gene system in the treatment of tongue carcinoma cell line].

OBJECTIVE: To study the effects of replication-defective recombinant adenovirus-mediated herpes simplex virus thymidine kinase (AdCMV HSV-TK)/ganciclovir (GCV) suicide gene system on tongue carcinoma cell line. METHODS: Replication-defective recombinant adenovirus containing CMV promoter were propagated in 293 cells, purified by cesium chloride gradient and titrated by tissue culture infectious doses50 (TCID50) methods. Infectivity test was used to determine the efficiency of adenoviral transduction into tongue carcinoma cell line (Tca8113 cell line) and RT-PCR was applied to detect the expression of TK gene after infecting Tca8113 cells. The killing effects and bystander effects of HSV-TK/GCV system on tongue carcinoma cells were detected with MTT assay. RESULTS: The adenoviral titration was about 2 x 10(10) plaque-forming units(PFU)/ml. The efficiency of adenoviral transduction into tongue carcinoma cells was more than 70 percent when multiplicity of infection (MOI) was more than 20. The recombinant adenovirus expressed TK gene after infecting Tca8113 cells in vitro. Adenovirus-mediated HSV-TK/GCV suicide gene system had killing effects on Tca8113 cells and these effects were related with time and GCV dose. The killing effects were poor after treated for 3 days and increased for 5 and 7 days. There had a good killing effect only when MOI was more than 20. When MOI was 80, GCV 5 x 10(-4) mol/L and treatment for 7 days, the viability of cells is only 4%. The bystander effect of this system on Tca8113 cells is poor. CONCLUSIONS: Only when most of the tongue carcinoma cells were transferred by AdCMV HSV-TK, HSV-TK/GCV suicide gene system has good killing effect on tongue carcinoma cell line.

Adenoviridae↗

PubMed2001

[Guided tissue regeneration with Biomesh membrane for Class II furcation defects].

OBJECTIVE: The objective of this study was to investigate clinical significance of the guided tissue regeneration (GTR) by using Biomesh membrane to the treatment of Class II furcation defects. METHODS: Totally 8 molars with Class II furcation defects of 6 periodontitis patients were treated. The clinical effects of GTR were evaluated by measuring changes of pocket probing depths (PPD), clinical attachment levels (CAL), and alveolar bone on X-ray films prior to and 6 months after the surgery. RESULTS: All patients had no swollen or pain reaction on these surgery areas after the surgery, and the PPD was reduced and the CAL was gain significantly 6 months after the surgery. The new alveolar bone formation was demonstrated. CONCLUSION: The GTR with Biomesh membrane is a good therapy method for Class II furcation defects.

Adult↗

PubMed2001

[Correlation of p16 mutation and biological behavior in Chinese laryngeal cancer].

OBJECTIVE: To investigate the correlation between p16 gene mutation and laryngeal cancer biological behavior as well as its prognosis in laryngeal cancer. METHOD: 24 specimens of primary laryngeal cancer and 10 speciments with benign lesion in larynx were examined for mutations in exon2 of p16 by using PCR-SSCP silver stainning technique. RESULT: Mutations frequency of laryngeal cancer was 62.5% (15/24). Nothing was found in 10 cases with laryngeal benign lesion. CONCLUSION: There is a strong correlation between p16 gene mutation and the biological behavior of chinese laryngeal cancer, such as histologic differentiation, invasion stage, and regional lymph nodes metastasis (P < or = 0.05). PCR-SSCP silver stainning technique is one of the most sensitive and simplest measure for detecting genetic mutation. It is worth using in clinical laboratory because of its readiness, repetition and lower cost.

Genes, p16↗

PubMed2001

[Primary restoration for congenital malformation of external and middle ear].

OBJECTIVE: To promote the hearing, improve the appearance, shorten the therapeutic course in congenital malformation of external and middle ear, the program of primary restoration has been designed. METHOD: Under general or local anaesthesia a Z-shaped incision is made in skin. After turn up the flap A (defective ear) and flap B(retroauricular skin), a periosteal flap C with pedicle in front is made and elevated from mastoid. Then made frameworklize on mastoid and perform tympanoplasty. Once the myringograft is put properly the flap C is turn into the mastoidal cavity to serve as the lining of anterior wall. Flap A is sutured with the edge of retroauricular incision to serve as the lower part of new auricle. Then use the flap B to wrap a siliceous frame to make the upper part of new auricle. Finally, the naked walls of mastoidal cavity are lined with free skin graft and the cavity is packed with vaseline gauze for two weeks. RESULT: Two cases of congenital malformation of external and middle ear were treated with the procedure mentioned above and were followed up for one and 3 years respectively. Both effects of shape and hearing were good. CONCLUSION: The primary restoration for congenital malformation of external and middle ear designed by the authors is an excellent method worthy to be recommended.

Adolescent↗

PubMed2001

[Diagnostic value of computer-based endoscopy system].

OBJECTIVE: To assess the roles of computer-based endoscopy system as a clinical tool in evaluation of laryngeal disorder. METHOD: An extensive research of 100 patients under stroboscopy examination with acoustic and EGG signal was made, and a number of quantitative information, such as contact quotient, glottal noise and glottal area changes, was examined. RESULT: Quantitative information contributes significant diagnostic information in 14 cases, resulted in avoidance of surgery in 6 cases and 8 cases referred to surgery instead of voice and medical therapy. CONCLUSION: Acoustic and EGG measures should be used as substantially complements of endoscopy examination in the routine clinical examination.

Glottis↗

PubMed2001

[Effect of Ce3+ on reactive oxygen species in cells].

The effect of Ce3+ on the content of (reactive oxygen species ROS) in hepatocytes and V79 cells was studied with microfluorometry. The results showed that Ce3+ could enhance the concentration of ROS in hepatocytes in high dose and reduce the concentration of ROS in low dose. These results suggested that Ce3+ might decrease the damage of lipid peroxidation and DNA in low dose and might increase the damage of lipid peroxidaion and DNA in high dose.

Animals↗

PubMed2001

[Determination of residues of organic chloride pesticide in Chinese medicinal materials with capillary gas chromatography].

Residues of organic chloride pesticide were separated and detected successfully with high performance capillary column and high sensitive electron capture detector, such as hexachloro-cyclohexane, dichloro-diphenyl-trichloroethane, pentachloronitrobenzene. The method can be used for the determination of residues of organic chloride pesticide in Chinese medicinal materials, and the residue enriching in the different part of plant body was tested preliminary.

China↗

PubMed2001

[Surgical procedure of gynecologic malignances in patients over 70 years].

OBJECTIVE: To assess the viability of performing surgical procedure on gynecologic malignances patients over 70 years old. METHODS: A retrospective study of all patients 70 years of age and older treated by surgical procedure for gynecologic malignances was performed between September 1, 1983, and June 30, 1999. RESULTS: Fifty-seven patients were older than 70 years of age at the time of the diagnosis. Mean age of the patients was 73.5 years. In thirty-four patients a extensive surgical procedure was carried out, while in twenty-three patients a conservative surgery was done. Seventy-one percent of patients had one or more preexisting medical illnesses. Minor surgical morbidity occurred in 31.6% of the patients, while major surgical morbidity occurred in 10.5% of the patients. There were no differences in the type of surgical procedure, mean hospital stay, preexisting medical illness and postoperative complication between patients 70 to 75 and over age 75. The total major postoperative complications occurred in extensive surgical procedure group and postoperative mean stay was also significantly length. CONCLUSIONS: The extensive surgical procedure is a safe treatment for elderly patients with gynecologic malignances. Careful preoperative assessment, monitoring, and meticulous postoperative care are vital to the success.

Aged↗

PubMed2001

[Construction and expression of single chain Fv antibody against human bladder carcinoma].

OBJECTIVE: To construct and express single chain Fv antibody against human bladder carcinoma, which was expected to have advantages in targeted diagnosis and therapy with the characteristics of lower immunogenicity. METHODS: Hybridoma BDI-1 cell, which secreted a monoclonal antibody against human bladder carcinoma, was used to isolate total RNA. By reverse transcription, the cDNA was synthesized and used as templates for amplifying the immunoglobulin heavy-and light-chain variable region genes by polymerase chain reaction (PCR). The amplified DNA was ligated into a sequencing vector pUC19 and sequenced with Sanger's method. The VH and VL genes were inserted into expression vector pFUW80. By inducing, the ScFv antibodies were expressed and secreted from Escherichia coli. Binding activities against the bladder carcinoma cells were detected by ELISA. The 5 x his-tagged ScFv antibodies were purified on IDA-Ni2+ resin by immobilized metal chelate affinity chromatography (IMAC). The purified ScFv antibodies were analyzed by SDS-PAGE. RESULTS: A full-length of VH and VL genes was 366 and 324 base pairs respectively. Comparing with other published sequences, the VH gene was a member of mouse heavy-chain VH subgroup II and originated from re-arrangement of VH, Dsp2.2 and JH4; the VL gene was VK subgroup IV and from Vk and Jk4. The ScFv antibodies could inhibit 84% of the antigen binding activity of original McAb BDI-1. The purified ScFv antibodies gave a single major band (Mr-29 000) on SDS-PAGE. CONCLUSION: The single chain Fv antibody against human bladder carcinoma was successfully constructed and expressed.

Amino Acid Sequence↗

PubMed2000

Down-regulation of reduced folate carrier gene (RFC1) expression after exposure to methotrexate in ZR-75-1 breast cancer cells.

Methotrexate (MTX) is administered in intervals of one week or longer in the treatment of cancer and autoimmune disease. Early studies suggested that daily MTX administration was associated with decreased effectiveness and increased toxicity, leading to schedules of administration that include periodic intervals of rest during chronic MTX therapy. We hypothesized that these observations may be the result of the down-regulation of the reduced folate carrier, the major route of cellular uptake of both MTX and the endogenous folates, after MTX exposure. We exposed folate-depleted ZR-75-1 breast cancer cells to low-dose MTX in the presence of hypoxanthine, adenosine and thymidine. After 72 h, the initial rate of MTX uptake had decreased to 22% of the Day 0 value. Western blot analysis showed down-regulation of RFC1 protein expression, and Northern blot analysis showed a corresponding decrease in RFC1 RNA levels. Using an RT-PCR assay, we found that levels of RNA transcripts containing each of the three RFC1 5' noncoding exons were decreased after exposure to MTX, suggesting that MTX exposure causes transcriptional down-regulation of RFC1. Promoter-reporter construct assays demonstrated decreased activity of RFC1 promoter elements upstream of these exons after MTX exposure. Preexposure of the ZR-75-1 cells to 5-azacytidine, a DNA methylation inhibitor, further decreased MTX uptake rather than reverse the inhibition of RFC1 activity, indicating that RFC1 down-regulation after MTX exposure is not the result of methylation of the RFC1 promoter. In summary, these studies demonstrate that MTX exposure can down-regulate RFC1 expression and activity. These acute, inducible, epigenetic changes in RFC1 expression may ultimately be molded into the more permanent genetic changes that result in the transport-mediated MTX resistance that have been observed in MTX-resistant cell lines.

Antimetabolites, Antineoplastic↗

PubMed2000

Disruption of an active site hydrogen bond converts human heme oxygenase-1 into a peroxidase.

The crystal structure of heme oxygenase-1 suggests that Asp-140 may participate in a hydrogen bonding network involving ligands coordinated to the heme iron atom. To examine this possibility, Asp-140 was mutated to an alanine, phenylalanine, histidine, leucine, or asparagine, and the properties of the purified proteins were investigated. UV-visible and resonance Raman spectroscopy indicate that the distal water ligand is lost from the iron in all the mutants except, to some extent, the D140N mutant. In the D140H mutant, the distal water ligand is replaced by the new His-140 as the sixth iron ligand, giving a bis-histidine complex. The D140A, D140H, and D140N mutants retain a trace (<3%) of biliverdin forming activity, but the D140F and D140L mutants are inactive in this respect. However, the two latter mutants retain a low ability to form verdoheme, an intermediate in the reaction sequence. All the Asp-140 mutants exhibit a new peroxidase activity. The results indicate that disruption of the distal hydrogen bonding environment by mutation of Asp-140 destabilizes the ferrous dioxygen complex and promotes conversion of the ferrous hydroperoxy intermediate obtained by reduction of the ferrous dioxygen complex to a ferryl species at the expense of its normal reaction with the porphyrin ring.

Heme Oxygenase (Decyclizing)↗

PubMed2000

Gene expression profiling of low-grade diffuse astrocytomas by cDNA arrays.

Diffuse astrocytoma WHO grade II is a well-differentiated, slowly growing tumor that has an inherent tendency to progress to anaplastic astrocytoma (WHO grade III) and, eventually, to glioblastoma (WHO grade IV). Little is known about its molecular basis, except for p53 mutations that are found in >60% of cases. In a search for additional genetic alterations, we carried out gene expression profiling of 11 diffuse astrocytomas using cDNA expression arrays. Expression of six genes (TIMP3, c-myc, EGFR, DR-nm23, nm23-H4, and GDNPF) was detected in 64-100% of diffuse astrocytomas, but not in nontumorous brain tissue. Seven genes (AAD14, SPARC, LRP, PDGFR-alpha, 60S ribosomal protein L5, PTN, and hBAP) were found to be up-regulated more than 2-fold in 20-60% of cases, whereas 11 genes (IFI 9-27, protein kinase CLK, TDGF1, BIN1, GAB1, TYRO3, LDH-A, adducin 3, GUK1, CDC10, and KRT8) were down-regulated to less than 50% of normal levels in 64-100% of cases. Semiquantitative conventional reverse transcription-PCR was performed for 11 genes, 9 of which showed an expression profile similar to that obtained with cDNA expression arrays. Immunohistochemical staining for SPARC showed cytoplasmic immunoreactivity of neoplastic cells in all diffuse astrocytomas analyzed. These results indicate significant changes in gene expression in diffuse astrocytomas, but it remains to be shown which of these are causally related to the transformation of glial cells.

Adult↗

PubMed2000

Mechanism and prevention of cold storage-induced human renal tubular cell injury.

BACKGROUND: The recent observation that cold storage of kidneys and tubular cells causes marked increase in free radical-catalyzed F2-isoprostanes suggests that radicals might be formed during cold storage. As cold temperature is associated with reduced metabolic and enzymic activity, the notion that cold temperature causes free radical production appeared less tenable. The objective was, therefore, to seek direct evidence for the free radical production during the cold storage of human renal tubular cells, and to define the roles of extrinsic and intrinsic antioxidants in cold-induced cell injury. METHODS: Human renal tubular cells were cold-stored at 4 degrees C for varying duration in University of Wisconsin solution and subjected to mRNA analysis, biochemical measurements, and cytoprotective studies. RESULTS: Cold storage caused a time-dependent reduction in glutathione levels, and an increase in the formation superoxide, hydrogen peroxide, and hydroxyl radicals. Cold-induced lactate dehydrogenase (LDH) release, ATP depletion, DNA damage, and membrane degradation were suppressed with the inclusion of antioxidant 2-methyl aminochroman or deferroxamine. The cells that were structurally protected with antioxidants were also intact functionally, as they had significantly improved cell proliferation. To examine the effect of cold on intrinsic antioxidant gene expression, antioxidant mRNA levels were analyzed using reverse transcription-polymerase chain reaction. The gene expression of mitochondrial Mn-superoxide dismutase (SOD), but not of cytosolic Cu,Zn-SOD or of glutathione peroxidase expression increased with cold exposure. The oxidant-sensitive gene heme oxygenase I increased slightly with 48-hr cold storage. CONCLUSIONS: Cold storage of human tubular cells causes marked increase in free radicals. These are likely of mitochondrial origin as there is a differential inducement of Mn-SOD gene, and are causal to cold-induced cell injury as extrinsic antioxidants abrogated the injury. Our findings support the strategy of adding antioxidants to preservation solutions or the strategy of pre-conditioning the organs to oxidative stress to minimize cold storage-induced organ damage.

Adenosine↗

PubMed2000

Enhancement in activities of large conductance calcium-activated potassium channels in CA1 pyramidal neurons of rat hippocampus after transient forebrain ischemia.

It has been reported previously that the neuronal excitability persistently suppresses and the amplitude of fast afterhyperpolarization (fAHP) increases in CA1 pyramidal cells of rat hippocampus following transient forebrain ischemia. To understand the conductance mechanisms underlying these post-ischemic electrophysiological alterations, we compared differences in activities of large conductance Ca(2+)-activated potassium (BK(Ca)) channels in CA1 pyramidal cells acutely dissociated from hippocampus before and after ischemia by using inside-out configuration of patch clamp techniques. (1) The unitary conductance of BK(Ca) channels in post-ischemic neurons (295 pS) was higher than that in control neurons (245 pS) in symmetrical 140/140 mM K(+) in inside-out patch; (2) the membrane depolarization for an e-fold increase in open probability (P(o)) showed no significant differences between two groups while the membrane potential required to produce one-half of the maximum P(o) was more negative after ischemia, indicating no obvious changes in channel voltage dependence; (3) the [Ca(2+)](i) required to half activate BK(Ca) channels was only 1 microM in post-ischemic whereas 2 microM in control neurons, indicating an increase in [Ca(2+)](i) sensitivity after ischemia; and (4) BK(Ca) channels had a longer open time and a shorter closed time after ischemia without significant differences in open frequency as compared to control. The present results indicate that enhanced activity of BK(Ca) channels in CA1 pyramidal neurons after ischemia may partially contribute to the post-ischemic decrease in neuronal excitability and increase in fAHP.

Animals↗

PubMed2000

Parkin functions as an E2-dependent ubiquitin- protein ligase and promotes the degradation of the synaptic vesicle-associated protein, CDCrel-1.

Parkinson's disease is a common neurodegenerative disorder in which familial-linked genes have provided novel insights into the pathogenesis of this disorder. Mutations in Parkin, a ring-finger-containing protein of unknown function, are implicated in the pathogenesis of autosomal recessive familial Parkinson's disease. Here, we show that Parkin binds to the E2 ubiquitin-conjugating human enzyme 8 (UbcH8) through its C-terminal ring-finger. Parkin has ubiquitin-protein ligase activity in the presence of UbcH8. Parkin also ubiquitinates itself and promotes its own degradation. We also identify and show that the synaptic vesicle-associated protein, CDCrel-1, interacts with Parkin through its ring-finger domains. Furthermore, Parkin ubiquitinates and promotes the degradation of CDCrel-1. Familial-linked mutations disrupt the ubiquitin-protein ligase function of Parkin and impair Parkin and CDCrel-1 degradation. These results suggest that Parkin functions as an E3 ubiquitin-protein ligase through its ring domains and that it may control protein levels via ubiquitination. The loss of Parkin's ubiquitin-protein ligase function in familial-linked mutations suggests that this may be the cause of familial autosomal recessive Parkinson's disease.

Amino Acid Sequence↗

PubMed2000

Replacement of the distal glycine 139 transforms human heme oxygenase-1 into a peroxidase.

The human heme oxygenase-1 crystal structure suggests that Gly-139 and Gly-143 interact directly with iron-bound ligands. We have mutated Gly-139 to an alanine, leucine, phenylalanine, tryptophan, histidine, or aspartate, and Gly-143 to a leucine, lysine, histidine, or aspartate. All of these mutants bind heme, but absorption and resonance Raman spectroscopy indicate that the water coordinated to the iron atom is lost in several of the Gly-139 mutants, giving rise to mixtures of hexacoordinate and pentacoordinate ligation states. The active site perturbation is greatest when large amino acid side chains are introduced. Of the Gly-139 mutants investigated, only G139A catalyzes the NADPH-cytochrome P450 reductase-dependent oxidation of heme to biliverdin, but most of them exhibit a new H(2)O(2)-dependent guaiacol peroxidation activity. The Gly-143 mutants, all of which have lost the water ligand, have no heme oxygenase or peroxidase activity. The results establish the importance of Gly-139 and Gly-143 in maintaining the appropriate environment for the heme oxygenase reaction and show that Gly-139 mutations disrupt this environment, probably by displacing the distal helix, converting heme oxygenase into a peroxidase. The principal role of the heme oxygenase active site may be to suppress the ferryl species formation responsible for peroxidase activity.

Glycine↗

PubMed2000

Transient inhibition of interleukin 4 signaling by T cell receptor ligation.

Interleukin (IL)-4 and IL-12 together with T cell receptor (TCR) engagement are crucial for the differentiation of CD4(+) T cells into T helper (Th)2 or Th1 cells, respectively. Although IL-4 receptors (IL-4Rs) but not IL-12Rs are expressed on naive CD4(+) T cells, IL-4 has no apparent advantage over IL-12 in driving naive T cell differentiation when the cells are primed with both IL-4 and IL-12 in vitro. It was found that IL-4-induced phosphorylation of Janus kinases 1 and 3, IL-4R alpha, signal transducer and activator of transcription 6, and insulin receptor substrate 2 was strikingly but transiently inhibited by TCR ligation both in conventional and TCR transgenic T cells. TCR engagement also blocked the expression of an IL-4-inducible gene. Signals induced by other cytokines, including IL-2, IL-6, and interferon alpha, but not by insulin-like growth factor 1, were also blocked by TCR engagement. The capacity of various inhibitors to reverse TCR-mediated inhibition of IL-4 signaling suggested that activation of the Ras-mitogen-activated protein kinase pathway and of the calcineurin pathway contribute to desensitizing IL-4R. IL-4 responsiveness returned at about the time ( approximately 12 h) that IL-12-mediated signaling was first observed. Thus, through different mechanisms, neither IL-4R nor IL-12R has any clear advantage in polarizing cells; rather, the availability of cytokine is probably the limiting factor in this process.

Animals↗

PubMed2000

A conformational change in PBX1A is necessary for its nuclear localization.

The fly homeodomain (HD) protein EXTRADENTICLE (EXD) is dependent on a second HD protein, HOMOTHORAX (HTH), for nuclear localization. We show here that in insect cells the mammalian homolog of EXD, PBX1A, shows a similar dependence on the HTH homologs MEIS1, 2, and 3 and the MEIS-like protein PREP1. Paradoxically, removal of residues N-terminal to the PBX1A HD abolishes interactions with MEIS/PREP but allows nuclear accumulation of PBX1A. We use deletion mapping and fusion to green fluorescent protein to map two cooperative nuclear localization signals (NLSs) in the PBX HD. The results of DNA-binding assays and pull-down experiments are consistent with a model whereby the PBX N-terminus binds to the HD and masks the two NLSs. In support of the model, a mutation in the PBX HD that disrupts contact with the N-terminus leads to constitutive nuclear localization. The HD mutation also increases sensitivity to protease digestion, consistent with a change in conformation. We propose that MEIS family proteins induce a conformational change in PBX that unmasks the NLS, leading to nuclear localization and increased DNA-binding activity. Consistent with this, PBX1 is nuclear only where Meis1 is expressed in the mouse limb bud.

Amino Acid Sequence↗