Biomedical subjects

N Huang

Publications and source records attributed to N Huang.

At least 55 records · Page 3Linked to original sources

PubMed2000

[Enhancement of BCG-induced hBD-1 mRNA expression in human pulmonary gland epithelial cells].

Using reverse-transcription PCR (RT-PCR) and Northern blot analysis, the present authors found an enhanced expression of the human beta-defensin 1 (hBD-1) gene in the SPC-A-1 cells challenged with heat-killed M. Bovis Bacille Calmette-Guerin (BCG). The enhanced expression of hBD-1 mRNA was dose- and time-dependent. This result indicated a significant progress in the work of developing a new antimicrobial strategy that enhances mucosa antibiotic peptide expression for the prevention and treatment of mucosal infections.

BCG Vaccine↗

PubMed1999

High-level expression of I kappa B-beta in the surface epithelium of the colon: in vitro evidence for an immunomodulatory role.

The intestinal epithelium is spatially segregated into two compartments, one containing undifferentiated cells in a proliferative state and one with non-proliferative differentiated cells. Although this epithelium can produce many immunemodulating substances, emerging evidence suggests that the differentiated cell compartment is less immune responsive. Indeed, it is the differentiated cellular compartment that represents the interface between the highly antigenic luminal environment and the mucosal immune system. The NF-kappaB/rel family of transcriptional activators play a critical role in regulating the inflammatory response by activating a wide variety of immune-modulating genes. These transcription factors are maintained in an inactive state in the cytoplasmic compartment by interaction with inhibitory proteins of the IkappaB family. In this study we show by immunohistochemistry that IkappaB-beta is expressed at high levels specifically in the differentiated surface epithelium of the colonic mucosa. Using a naturally occurring compound found in the colon of vertebrates, butyrate, we provide evidence in an intestinal cell line that alteration of IkappaB-beta expression can modulate the transcriptional activation of the interleukin-8 (IL-8) gene by preventing the nuclear translocation of NF-kappaB proteins. Therefore, the expression of IkappaB-beta in the differentiated surface epithelium of the colon may help these cells act as an immunological barrier to prevent activation of the mucosal immune system.

Adjuvants, Immunologic↗

PubMed1999

Effects of antipsychotic drugs on dopamine and serotonin contents and metabolites, dopamine and serotonin transporters, and serotonin1A receptors.

The effects of neuroleptics have been attributed to dopamine (DA) receptor blockade; however, other neurotransmitters, in particular serotonin (5-HT), have also been implicated. In this study, we examined the effects of clozapine and haloperidol on the distribution of DA and 5-HT transporters, on endogenous DA, 5-HT and their major metabolites, and on 5-HT1A receptors. Adult male Sprague-Dawley rats were treated with either haloperidol (1 mg/kg/day, i.p.), clozapine (20 mg/kg/day, i.p.) or saline for 21 days, and following 3 days of withdrawal, the brains were removed. Tissue levels of DA and 5-HT and their metabolites were measured by high-performance liquid chromatography in 16 brain regions, while quantitative autoradiography with [125I]RTI-121, [3H]citalopram and [3H]8-OH-DPAT was employed to label DA transporters, 5-HT transporters and 5-HT1A receptors, respectively. After haloperidol, densities of 5-HT transporters were increased in the dorsal insular cortex and in the ventral half of caudal neostriatum, while 5-HT1A receptors augmented in cingulate cortex but decreased in the entorhinal area. After clozapine, [3H]citalopram labelling was increased in ventral hippocampus, ventral caudal neostriatum and nucleus raphe dorsalis, but decreased in medio-dorsal and latero-dorsal neostriatum as well as in substantia nigra. Binding of [3H]8-OH-DPAT following clozapine was decreased in frontal, parietal, temporal and entorhinal cortices but increased in the CA3 division of Ammon's horn. The changes in 5-HT transporters in nucleus raphe dorsalis and substantia nigra, as well as the 5-HT1A receptor down-regulations caused by clozapine but not by haloperidol, may explain effects obtained with clozapine and other atypical neuroleptics. There were no modifications in densities of DA transporters, nor of tissue DA levels, after the chronic neuroleptic treatments. The results are in line with previous suggestions that a certain degree of tolerance to neuroleptics develops, in spite of profound D1 and D2 receptor changes that persist during the entire chronic treatment with these psychotropic agents.

Animals↗

PubMed1999

Altered pituitary sensitivity to corticotropin-releasing factor and arginine vasopressin participates in the stress hyporesponsiveness of lactation in the rat.

The regulation of the activity of the hypothalamic-pituitary-adrenal (HPA) axis is modified during lactation, wherein a blunted stress-induced adrenocorticotropic hormone (ACTH) and glucocorticoid secretion is coupled with elevated basal secretion of these hormones. The involvement of pituitary modifications in lactation-induced stress hyporesponsiveness has yet to be established. In this study we tested the hypothesis that the pituitary sensitivity to corticotropin-releasing factor (CRF) and arginine vasopressin (AVP) is altered in lactation in the rat. We examined the effect of exogenous CRF (0.1-5 microg/rat), AVP (0.01-0.5 microg/rat), and AVP (0.01-0.5 microg/rat)+CRF (0.1 microg/rat) on the ACTH response of virgin, mid-lactating (lactation day 10-12) females, as well as nursing females separated from their pups for 48 h. Additionally, to determine if changes in CRF- or AVP-receptor densities might mediate alterations in pituitary sensitivity, we compared pituitary CRF- and AVP-receptor binding by autoradiography in pregnant, mid-lactating, and virgin female rats. While both virgin and lactating female rats exhibited significant ACTH responses to CRF, the responses to the highest doses of CRF (2.0 and 5.0 microg/rat) were greater in virgin than in lactating females. Separation of the litter for 48 h partially restored pituitary responsiveness to 2.0 microg of CRF. Conversely, whereas lactating females displayed robust ACTH secretion following a high dose of AVP or following a combination of AVP+CRF, the response of virgin females was much smaller. These modifications in pituitary responsiveness were not accompanied by significant differences in pituitary CRF-and AVP-receptors levels between female groups. Our results demonstrate that a reduction in pituitary sensitivity to CRF, but not to AVP occur during lactation in the rat which mediates, at least in part, the stress hyporesponsiveness of lactation.

Adrenocorticotropic Hormone↗

PubMed1999

RAPD mapping in a doubled haploid population of rice (Oryza sativa L.).

To examine the distribution and genome coverage of RAPDs, a total of 242 Random Amplified Polymorphic DNA (RAPD) markers generated by 73 random decamer primers were mapped onto 12 rice chromosomes by linkage analysis using a doubled haploid population, developed from an indica x japonica cross. The RAPD markers were derived from both parents equally and were well distributed over the rice genome. Furthermore, multiple RAPD markers generated from the same primer were dispersed over different chromosomes rather than clustered. The RAPD technique provided improved marker coverage on a previously developed RFLP map. A set of primers producing reproducible markers originating from either parent and equally spaced over all the 12 chromosomes were selected for application in marker-assisted backcross breeding. The RAPD analysis as a realistic and practical alternative to RFLP and their usefulness in anchoring the identified BAC contigs directly to chromosomes is discussed.

Base Sequence↗

PubMed1999

Development of PCR-based markers for thermosensitive genetic male sterility gene tms3(t) in rice (Oryza sativa L.).

Development of simple and reliable PCR-based markers is an important component of marker-aided selection (MAS) activities for agronomically important genes in rice breeding. In order to develop PCR-based markers for a rice thermosensitive genetic male sterility gene tms3(t), located on chromosome 6, the nucleotide sequences of four linked RAPD markers OPF18(2600), OPAC3(640), OPB19(750) and OPM7(550) were used to design and synthesize several pairs of specific primers for PCR amplification of the genomic DNA of both the parents IR32364TGMS (sterile) and IR68 (fertile), involved in mapping this gene. For the RAPD marker OPF 18(2600), two pairs of specific primer pair combination from different positions of the sequence resulted in generation of two codominant STS (Sequence Tagged Sites) markers. In case of markers OPAC3(640), OPB19(750) and OPAA7(550) the first two could generate dominant polymorphism, while the last one could not be successful in PCR amplification. Both the codominant STSs with primer combinations F18F/F18RM and F18FM/F18RM were found to be tightly linked to the tms3(t) gene with a genetic distance of 2.7 cM. The sizes of the different alleles in case of F18F/F18RM, F18FM/F18RM combinations were 2300 bp, 1050 bp, and 1900 bp, 1000 bp respectively. The efficiency of marker-assisted selection for this trait was estimated as 84.6%. Polymorphism survey of 12 elite rice lines, indicated that these PCR-based markers for tms3(t) can now be used in selecting TGMS plants at seeding stage in the segregating populations in environment independent of controlled temperature regime.

Base Sequence↗

PubMed1999

[Cloning of rat beta-defensin rBD-1 cDNA].

This is a study aimed at the molecular mechanisms of beta-defensins gene expression and it's gene transfer experiments for preventing mucosal infection. A rat rBD-1 cDNA was cloned. The total RNA was isolated from rat kidney. The cDNA fragment was amplified by RT-PCR with specific primers. The purified RT-PCR product was cloned in pGEM-T Easy vector. The results of restriction endonuclease pattern analysis of the recombinant plasmid, DNA sequencing, and aligning of the putative amino acid sequence with hBD-1 and mBD-1 demonstrated that rat beta-defensin rBD-1 gene was cloned successfully.

Amino Acid Sequence↗

PubMed1999

[Experimental study of the effect of dexamethasone on pulmonary diffuse hemorrhage and energy metabolism of mitochondria in the liver of guinea pig infected with leptospirosis].

This experiment was designed to study the curative effect of dexamethasone on leptospirosis with pulmonary diffuse hemorrhage (PDH) in guinea pig model. The guinea pigs were randomly divided into four groups: the infected group, all animals developed PDH(n = 10); the infected plus treated group(n = 10); the treated control group(n = 10); and the normal control group(n = 10). The gross and microscopic observations in lung, liver and kidney were made. Also, ultrastructural changes of mitochondria in liver were examined, and the lactic acid level and mitochondrial ATPase activity in liver were determined. The results showed that there was significant difference in mortality, in gross and microscopic changes in lung, liver and kidney, and in the changes of mitochondrial ultrastructures, ATPase activity and lactic acid level in liver between the infected group and the infected plus treated group (P < 0.01). These findings suggest that the pharmacologic dose of dexamethasone injected intravenously in the early stage of PDH may have some beneficial effect on the emergency treatment of leptospirosis with PDH. The mechanism appears to be related to its effect on the inhibition of glycolysis and increasing oxidative phosphorylation in mitochondria.

Adenosine Triphosphatases↗

PubMed1999

[Detection of HNP1 gene expression by RT-PCR in transfected tracheal epithelial cells].

By using lipofection reagent DOSPER, the plasmid vector carrying the human neutrophil defensin HNP1 gene(pBabe-Neo-HNP1) was transferred into human, rabbit tracheal epithelial cells cultured in serum-free complement medium. Determination of HNP1 mRNA expression in tracheal epithelial cells was performed by reverse transcription-polymerase chain reaction (RT-PCR). The result showed that HNP1-gene expression was detected both in human and rabbit transfected epithelial cells; while in untransfected epithelial cells, no specific signals were detected by RT-PCR. This result and the result of our previous determination by immunocytochemical staining both demonstrated that the epithelial cells could express the antibiotic peptide when transfected with its gene, suggesting that the mucosal antibiotic peptide gene transfer might develop a new antimicrobial approach to prevention and treatment of respiratory infections.

Animals↗

PubMed1999

[Isolation, purification and antibacterial activities of salivary histidine-rich polypeptides].

OBJECTIVE: To isolate and purify salivary histidine-rich-polypeptides (HRPs) and observe their antibacterial activities. METHODS: By using of preparative acid urea polyacrylamide gel electrophoresis (AU-PAGE), three major HRPs(HRP-1, HRP-3 and HRP-5) were purified from parotid saliva collected from healthy adults. Their antibacterial activities were tested in the ultrasensitive antibacterial assay, named radial diffusion assay. RESULTS: Each fraction of the three purified HRPs appeared as a single protein zone both in AU-PAGE and Tricine-SDS-PAGE. Their molecular weights are 3-5 kD as determined by Tricine-SDS-PAGE. All the three major HRPs showed potent bactericidal effects on Streptococcus mutans MT6R and Staphylococcus aureas ATCC25923. As to Escherichia coli ML-35P and Pseudomonas aeruginosa ATCC27853, HRP-3 and HRP-5 also demonstrated significant antibacterial activities, whereas HRP-1 did not show any inhibitory effects on the viability of them. CONCLUSION: The above results suggested that the method of preparative AU-PAGE we used in this study has the benefits of high resolution, simple manipulation and perfect results of purification. HRPs are important components to prevent oral tissue from bacterial infections, therefore play a potent role in the maintenance of the oral health.

Adult↗

PubMed1999

[A radioimmunologic assay of insulin in lateral pterygoid muscle after functional mandibular protrusion in rats].

OBJECTIVE: To investigate the effect of insulin on the lateral pterygoid muscle after functional mandibular protrusion in rats. METHODS: Radioimmunoassay was used to examine the level of insulin in lateral pterygoid muscle quantitatively after functional mandibular protrusion in young growing rats. RESULTS: The amount of insulin in lateral pterygoid muscle in young growing rats enhanced after functional mandibular protrusion. CONCLUSION: Insulin plays an important role in adaptive remodeling of lateral pterygoid muscle after functional mandibular protrusion.

Animals↗

PubMed1999

[An eight-factor analysis of early skeletal Class II malocclusion using Fränkel appliance].

OBJECTIVE: To investigate the change of eight-factor after Fränkel appliance treatment in skeletal class II malocclusions. METHODS: X-ray cephalometric film. RESULTS: Fränkel appliance can be used to enhance the growth of ramus (Factor 2) and body (Factor 1) of the mandible, decrease the angle of cranial base (Factor 8) and made the maxilla rotate (Factor 4) anteriorly, which were benefit to the treatment of class II malocclusion. However, neither the vertical (Factor 5) and sagittal (Factor 3) growth of maxilla nor the height of posterior alveolar bone (Factor 6) can be inhibited by use of Fränkel appliance. CONCLUSION: Fränkel appliance is suitable to the treatment of class II patients with deficient mandible and almost normal maxilla, while Fränkel appliance would rather not be used for patients with overgrown maxilla or vertical growth pattern.

Adolescent↗

PubMed1999

[Surface modification of low temperature isotropic pyrolytic carbon artificial heart valve material].

In this study, nitrogen ion implantation and titanium oxide film synthesized by ion beam enhanced deposition were adopted to treat low temperature isotropic pyrolytic carbon (LTIC). The chemical composition and valence state of the modified layer were determined by X-ray photoelectron spectroscopy (XPS) and Auger eletron spectroscopy (AES). The electric resisitance and the surface energy were measured by the four-probe system and the contact angle method respectively. The blood compatibility of the modified LTIC was evaluated by clotting time measurement and platelet adhesion test. The results showed that carbon-nitride was formed on the LTIC surface after N+ ion implantation, which had some effect on the improvement of blood compatibility, and a significant improvement of blood compatibility of LTIC coated by TiO2-x film was verified.

Animals↗

PubMed1999

[Pharmacognostic identification of Ampelopsis grossedentata].

Pharmacognostic identification of Ampelopsis grossedentata was carried out by studying its microscopic characteristics, UV spectra and TLC. The results may provide a scientific basis for the comprehensive development and utilization of the drug.

Ampelopsis↗

PubMed1998

Two distinct nuclear receptor interaction domains in NSD1, a novel SET protein that exhibits characteristics of both corepressors and coactivators.

NSD1, a novel 2588 amino acid mouse nuclear protein that interacts directly with the ligand-binding domain (LBD) of several nuclear receptors (NRs), has been identified and characterized. NSD1 contains a SET domain and multiple PHD fingers. In addition to these conserved domains found in both positive and negative Drosophila chromosomal regulators, NSD1 contains two distinct NR interaction domains, NID-L and NID+L, that exhibit binding properties of NIDs found in NR corepressors and coactivators, respectively. NID-L, but not NID+L, interacts with the unliganded LBDs of retinoic acid receptors (RAR) and thyroid hormone receptors (TR), and this interaction is severely impaired by mutations in the LBD alpha-helix 1 that prevent binding of corepressors and transcriptional silencing by apo-NRs. NID+L, but not NID-L, interacts with the liganded LBDs of RAR, TR, retinoid X receptor (RXR), and estrogen receptor (ER), and this interaction is abrogated by mutations in the LBD alpha-helix 12 that prevent binding of coactivators of the ligand-induced transcriptional activation function AF-2. A novel variant (FxxLL) of the NR box motif (LxxLL) is present in NID+L and is required for the binding of NSD1 to holo-LBDs. Interestingly, NSD1 contains separate repression and activation domains. Thus, NSD1 may define a novel class of bifunctional transcriptional intermediary factors playing distinct roles in both the presence and absence of ligand.

Amino Acid Sequence↗

PubMed1998

Screening for overlapping bacterial artificial chromosome clones by PCR analysis with an arbitrary primer.

In this article, we used PCR analysis with arbitrary primers (AP-PCR) to screen for overlapping bacterial artificial chromosome (BAC) clones and assembly of contigs. A rice BAC library with three genome equivalents was used to prepare pooled BAC DNA. Twenty-two arbitrary primers were used to survey the pooled BAC DNAs and individual BAC DNAs. Each primer identified 1-10 loci, and the average was 4.4 loci. There were 1-5 overlapping clones in each locus, and the average was 2.5 clones. A total of 245 BAC clones were identified as overlapping by AP-PCR and the identities were confirmed by DNA-DNA hybridization. The 245 BAC clones were then assembled into 80 contigs and 17 single-clone loci. The results indicated that PCR analysis with arbitrary primers is a powerful tool in screening for overlapping BAC clones with high accuracy and efficiency. The use of AP-PCR analysis should speed up the construction of physical maps of the plant and animal genomes, as well as the rice genome.

Base Sequence↗

PubMed1998

Consistent loss of functional transforming growth factor beta receptor expression in murine plasmacytomas.

Murine plasmacytomas are tumors of Ig-secreting plasma cells that can be induced in genetically susceptible BALB/c mice. The deregulation of the c-myc protooncogene is a critical oncogenic event in the development of plasmacytomas (PCTs) although it is not sufficient for their malignant transformation. We have demonstrated that PCTs produce active transforming growth factor beta (TGF-beta) in vitro. Because TGF-beta is a potent negative regulator of the proliferation and differentiation of B lymphocytes, we examined its role in plasmacytomagenesis by comparing responsiveness to TGF-beta of nonneoplastic plasma cells and PCTs. The nontransformed plasma cells that accumulate in interleukin 6 transgenic mice undergo accelerated apoptosis upon treatment with TGF-beta, but the 15 PCTs studied, including primary and transplanted tumors as well as established cell lines, were refractory to TGF-beta-mediated growth inhibition and apoptosis. Although PCTs lack functional TGF-beta receptors as demonstrated by chemical crosslinking to radiolabeled TGF-beta1, they nonetheless contain mRNA and protein for both type I and II TGF-beta receptors, suggesting a potential defect in receptor trafficking or processing. The results clearly show the consistent inactivation of TGF-beta receptors in plasmacytoma cells, demonstrating for the first time that interruption of a tumor suppressor pathway contributes to plasmacytomagenesis.

Animals↗

PubMed1998

Neuroleptics and dopamine transporters.

The effects of neuroleptic treatments on dopamine transporters and on dopamine receptors was investigated in the forebrain of adult rats treated for 21 days with either haloperidol, clozapine or saline. The dopamine D1 receptors, labeled with [3H]SCH23390, increased in nucleus accumbens, latero-dorsal rostral neostriatum and substantia nigra, after clozapine but not haloperidol. The dopamine D2 receptors, studied with [3H]raclopride, increased in nucleus accumbens and in dorso-lateral, ventro-medial and dorso-medial quadrants of the rostral neostriatum after either haloperidol or clozapine treatments, and also in latero-ventral rostral neostriatum but only after haloperidol. Haloperidol also up-regulated D2 receptors in rostral and caudal neostriatum, but clozapine produced a more uneven increase, especially in caudal neostriatum. In contrast, the densities of dopamine uptake sites, or transporters, labeled with [125I]RTI-121, remained unchanged after both neuroleptic treatments. The observation that dopamine transporters are resistant to treatments that modify D1 and D2 receptors indicates that these uptake sites can probably be ruled out as the target of neuroleptic drugs, and that dopamine receptor up-regulations can indeed occur independently of the densities of nerve endings at the terminal fields of innervation.

Animals↗