Biomedical subjects

H Jiang

Publications and source records attributed to H Jiang.

At least 343 records · Page 19Linked to original sources

PubMed1998

Neoplastic odontogenic epithelial cells express bone sialoprotein.

Bone sialoprotein (BSP) is synthesized and secreted by bone-, dentine- and cementum-forming cells and has been implicated in de novo bone formation and mineralization. In this study, we used histological sections of odontogenic neoplasms and performed immunohistochemical and in situ hybridization analyses. In ameloblastoma, BSP mRNA signals were seen in the neoplastic epithelial cells forming nests, strips and islands. BSP deposition was also seen in the stellate reticulum of the tumour masses revealed by immunohistochemistry using human BSP antibodies. In calcifying epithelial odontogenic tumour, the calcified masses demonstrated positive immunoreactivity to the human BSP antibodies, and the hybridization signals for BSP were located in the cells near the calcified particles. In the calcifying odontogenic cyst, strong BSP signals were seen in cells surrounding the characteristic nests of ghost cells, which often calcify subsequently. BSP protein was also found in these cells by immunohistochemistry. The active expression of BSP in the epithelial elements of the odontogenic tumours of adult patients suggests the activation of this matrix protein gene in the neoplastic process, and that BSP may play an important role in tumour formation and differentiation with respect to pathological calcification.

Adult↗

PubMed1998

Regulation of oleoyl-CoA synthesis in the peripheral nervous system: demonstration of a link with myelin synthesis.

We studied the regulation of oleic acid synthesis in the PNS. During mouse postnatal development, the proportion of 18:1 rises in the sciatic nerve from 17% at 5 days of age to 33% at 25 days. However, this rise does not occur in the dysmyelinating mutant mouse trembler. In normal mouse development, the total stearoyl-CoA desaturase (SCD) activity measured in sciatic nerve homogenates is high during the first 3 weeks. Yet in trembler nerves, this SCD activity represents only 15% of normal values. Using the RT-PCR technique, we demonstrate that the SCD2 isoform is predominantly expressed in the PNS. Northern blot analysis showed that the mRNA levels for SCD2 parallel those of other specific myelin proteins in both normal mouse and trembler mutant development. Similar experiments in a rat demyelination-remyelination model confirmed that SCD2 mRNA levels are regulated in the PNS in a similar manner to myelin-specific proteins.

Acyl Coenzyme A↗

PubMed1998

Improved continuous light diffusion imaging in single- and multi-target tissue-like phantoms.

The image reconstruction enhancement schemes of total variation minimization, dual meshing and iterative spatial filtering have been applied to laboratory data collected from continuous light illumination of tissue-like phantoms. Experiments include both single- and multi-target cases where variations in object size (4 mm to 20 mm), position (centred to near boundary) and contrast with the background (2:1 to 8:1) have been explored. The results show that dramatic improvements in image quality have been obtained in terms of geometric and spatial resolution measures relative to those previously reported for continuous light, but quantitative information on the actual optical properties of embedded heterogeneities is still lacking. Specifically, the geometric characteristics of object size, position and shape are generally accurate to 10-20% and the spatial resolution metrics of background-to-object size and neighbouring-edge separation are approximately 10:1. Direct comparisons are also made with images obtained with intensity-modulated light under identical experimental conditions. Images from intensity-modulated light are found to be superior to continuous light in several important ways, most notably in terms of the ability to quantitatively discriminate the optical property values of embedded targets from the surrounding background. Continuous-light images are also found to have centrally located artefacts in many instances which do not appear in the corresponding intensity-modulated cases.

Algorithms↗

PubMed1998

Differential induction of IL-12 by IFN-beta and IFN-gamma in human macrophages.

Interleukin-12 (IL-12) is a proinflammatory cytokine secreted by antigen-presenting cells (APC) in response to microbial antigens and mitogens. IL-12 induces interferon-gamma (IFN-gamma) production and enhances cellular immune responses. Conversely, IFN-gamma does not induce IL-12 but can prime its production by phagocytic cells in response to antigenic stimuli. In this study, we examined the effect of IFN-beta on IL-12 production in human macrophages, as IFN-beta is a natural protein produced by virus-infected cells. We demonstrate that, unlike IFN-gamma, IFN-beta is able to induce IL-12 production in macrophages. However, IFN-gamma can enhance IFN-beta-induced IL-12 in these cells. These findings suggest that IFN-beta could influence the immune response to virus infection indirectly through IL-12.

Cell Line↗

PubMed1998

Enamel epithelium expresses bone sialoprotein (BSP).

Bone sialoprotein (BSP) is a major non-collagenous extracellular matrix protein in bone and other mineralized connective tissues. BSP is synthesized and secreted by bone-, dentin- and cementum-forming cells. In this study we hypothesized that BSP may be also involved in enamel formation through its postulated role in matrix mineralization. In situ hybridization with cRNA probes for rat and hamster BSP, respectively, showed strong mRNA signals in ameloblasts actively synthesizing enamel matrix in developing incisors. However, no hybridization signals were observed at an earlier developmental stage when bell-shaped molar tooth germs were being formed. Immunohistochemical analysis of tooth tissues from transgenic mice harboring a 2.7 kb rat BSP promoter ligated to a luciferase reporter gene revealed strong staining for luciferase in the enamel epithelium of the developing tooth germ. Interestingly, BSP expression was also observed in epithelial cells of an ameloblastoma. The neoplastic epithelial nests and cords demonstrated strong mRNA signals to the human BSP probe while the connective tissue stroma showed only a background level of silver grains. Immunostaining also showed deposition of BSP by the odontogenic cells of the tumor. These results demonstrate that BSP is expressed by the enamel-forming epithelium of developing teeth, suggesting a possible role for BSP in enamel formation and its subsequent mineralization. Expression of the BSP gene in ameloblastomas is consistent with the expression of BSP by the enamel epithelium and also with the expression of BSP by neoplastic tissues, suggesting a possible role in tumorigenesis.

Ameloblastoma↗

PubMed1998

Complement regulatory proteins on the sperm surface: relevance to sperm motility.

PROBLEM: To determine whether complement regulatory proteins are present on human spermatozoa and whether antibodies to these proteins adversely affect sperm motility. METHOD OF STUDY: Human sperm membrane proteins were solubilized and subjected to polyacrylamide gel electrophoresis followed by Western blot analysis against antibodies to complement component 1 inhibitor (C1-INH), decay-activating factor (DAF; CD55), membrane cofactor protein (MCP; CD46), and homologous restriction factor (HRF; CD59). Spermatozoa, obtained by a swim-up technique, were incubated in medium (control 1) and medium supplemented with antibodies to human albumin (control 2) and antibodies to these complement regulatory proteins. We used a computerized sperm motion analysis to determine the effect of these antibodies on sperm motion characteristics. RESULTS: Complement regulatory proteins such as C1-INH, CD55, CD46, and CD59 were found in the sperm extracts as shown by Western blot analysis. The heat-treated (56 degrees C, 30 min) IgG fraction of antibodies to these proteins significantly reduced sperm motility in general and other motion parameters. Addition of complement did not affect these results except in the antibodies to CD46 in which the reducing action was further amplified. CONCLUSIONS: Our data suggest that C1-INH, CD55, CD46, and CD59 are present on the sperm surface. These proteins may have biological functions, such as affecting sperm motility, besides the complement regulatory functions. In infertile men and women with antibodies that recognize one or more of these complement regulatory proteins, there may be problems related to poor sperm motility and survival in the reproductive tracts.

Antigens, CD↗

PubMed1998

Levels of antibodies to transferrin and alpha 2-HS glycoprotein in women with and without endometriosis.

PROBLEM: To establish an enzyme-linked immunosorbent assay (ELISA) for determining the levels of antibodies to transferrin and alpha 2-HS glycoprotein in the serum of women with and without endometriosis. METHOD OF STUDY: Serum samples were obtained from 105 normal women, who were randomly selected for a population-based epidemiologic study, and 123 patients with active endometriosis. An ELISA using transferrin and alpha 2-HS glycoprotein as antigens was established. RESULTS: The levels of antibodies to transferrin and alpha 2-HS glycoprotein in the serum of patients with endometriosis were approximately 21 times higher than those in the serum of control subjects without endometriosis. Only 2% of control subjects had false positive levels of these antibodies, and 5% of patients with endometriosis had false negative levels of these antibodies (specificity, 98.1 and 98.1, respectively, for anti-transferrin and anti-alpha 2-HS glycoprotein; sensitivity, 95 and 96.7, respectively, for anti-transferrin and anti-alpha 2-HS glycoprotein). CONCLUSIONS: Patients with endometriosis have significantly higher levels of antibodies to transferrin and alpha 2-HS glycoprotein than control subjects. Testing women for antibodies to transferrin and alpha 2-HS glycoprotein will provide a specific noninvasive diagnosis of endometriosis.

Adolescent↗

PubMed1998

Frequency-domain near-infrared photo diffusion imaging: initial evaluation in multitarget tissuelike phantoms.

In this paper, an initial evaluation of our finite element based frequency-domain image reconstruction algorithm is performed for experiments where multiple millimeter-sized heterogeneities are embedded within a tissue-equivalent (optically) background medium having multicentimeter dimensions. The cases considered consist of several interesting geometry and optical property contrast combinations including (i) two different-sized targets with the same contrast at three different separation distances; (ii) two different-sized targets with different contrasts at two different separation distances; and (iii) three targets with the same and different sizes and contrasts, respectively. The reconstruction algorithm that has been used is an enhanced version of our originally developed regularized least squares approach that now includes total variation minimization, dual meshing, and spatial low-pass filtering. Quantitative measures of image quality including the size, location, and shape of the embedded heterogeneities along with errors in their recovered optical property values are presented. The results show that multiple targets can be clearly detected for all combinations of locations, sizes, and contrast levels considered, but the quantitative nature of this detection is influenced by these parameters.

Algorithms↗

PubMed1998

The 38-amino-acid form of pituitary adenylate cyclase-activating polypeptide induces neurite outgrowth in PC12 cells that is dependent on protein kinase C and extracellular signal-regulated kinase but not on protein kinase A, nerve growth factor receptor tyrosine kinase, p21(ras) G protein, and pp60(c-src) cytoplasmic tyrosine kinase.

The 38-amino-acid isoform of pituitary adenylate cyclase-activating polypeptide (PACAP38) elicits a robust outgrowth of neurites in cultured PC12 cells. Initiation of neurite outgrowth occurs within 4-8 hr after the addition of PACAP38. Treatment with PACAP38 does not elicit collateral activation of p140(trk) nerve growth factor receptor tyrosine kinase activity, nor is it associated with tyrosine phosphorylation of suc1-associated neurotrophic factor target, a selective target of neurotrophin tyrosine kinase receptors. Coadministration of epidermal growth factor with PACAP38 elicits an enhanced response. Induction of neurites is also observed on the addition of PACAP38 to dominant negative Src and Ras PC12 cell variants. PACAP38 stimulates extracellular signal-regulated kinase (Erk) activity >10-fold within 5 min, and the effect is augmented by cotreatment with epidermal growth factor. Pretreatment with the cAMP-dependent protein kinase-selective inhibitor, H-89, is ineffective as an antagonist of PACAP38-induced neurite outgrowth, whereas down-regulation of protein kinase C (PKC) by phorbol ester or incubation with PKC-selective inhibitors GF109203X and calphostin C effectively blocks PACAP38-stimulated neurite formation. Stimulation of Erk activity is inhibited by incubation with PD90859, a pharmacological antagonist of the threonine/tyrosine dual-specificity Erk. Inhibition of ligand-stimulated Erk activation prevents PACAP38-induced neurite outgrowth. Collectively, these findings indicate that PACAP38-stimulated neuritogenesis requires PKC and Erk activation but is independent of cAMP-dependent protein kinase, nerve growth factor receptor tyrosine kinase, p21(ras) G protein, and pp60(c-src) cytoplasmic tyrosine kinase.

Animals↗

PubMed1998

The gH-gL complex of herpes simplex virus (HSV) stimulates neutralizing antibody and protects mice against HSV type 1 challenge.

The herpes simplex virus type 1 (HSV-1) gH-gL complex which is found in the virion envelope is essential for virus infectivity and is a major antigen for the host immune system. However, little is known about the precise role of gH-gL in virus entry, and attempts to demonstrate the immunologic or vaccine efficacy of gH and gL separately or as the gH-gL complex have not succeeded. We constructed a recombinant mammalian cell line (HL-7) which secretes a soluble gH-gL complex, consisting of gH truncated at amino acid 792 (gHt) and full-length gL. Purified gHt-gL reacted with gH- and gL-specific monoclonal antibodies, including LP11, which indicates that it retains its proper antigenic structure. Soluble forms of gD (gDt) block HSV infection by interacting with specific cellular receptors. Unlike soluble gD, gHt-gL did not block HSV-1 entry into cells, nor did it enhance the blocking capacity of gD. However, polyclonal antibodies to the complex did block entry even when added after virus attachment. In addition, these antibodies exhibited high titers of complement-independent neutralizing activity against HSV-1. These sera also cross-neutralized HSV-2, albeit at low titers, and cross-reacted with gH-2 present in extracts of HSV-2-infected cells. To test the potential for gHt-gL to function as a vaccine, BALB/c mice were immunized with the complex. As controls, other mice were immunized with gD purified from HSV-infected cells or were sham immunized. Sera from the gD- or gHt-gL-immunized mice exhibited high titers of virus neutralizing activity. Using a zosteriform model of infection, we challenged mice with HSV-1. All animals showed some evidence of infection at the site of virus challenge. Mice immunized with either gD or gHt-gL showed reduced primary lesions and exhibited no secondary zosteriform lesions. The sham-immunized control animals exhibited extensive secondary lesions. Furthermore, mice immunized with either gD or gHt-gL survived virus challenge, while many control animals died. These results suggest that gHt-gL is biologically active and may be a candidate for use as a subunit vaccine.

Animals↗

PubMed1998

Structural and antigenic analysis of a truncated form of the herpes simplex virus glycoprotein gH-gL complex.

The herpes simplex virus (HSV) gH-gL complex is essential for virus infectivity and is a major antigen for the host immune system. The association of gH with gL is required for correct folding, cell surface trafficking, and membrane presentation of the complex. Previously, a mammalian cell line was constructed which produces a secreted form of gHt-gL complex lacking the transmembrane and cytoplasmic tail regions of gH. gHt-gL retains a conformation similar to that of its full-length counterpart in HSV-infected cells. Here, we examined the structural and antigenic properties of gHt-gL. We first determined its stoichiometry and carbohydrate composition. We found that the complex consists of one molecule each of gH and gL. The N-linked carbohydrate (N-CHO) site on gL and most of the N-CHO sites on gH are utilized, and both proteins also contain O-linked carbohydrate and sialic acid. These results suggest that the complex is processed to the mature form via the Golgi network prior to secretion. To determine the antigenically active sites of gH and gL, we mapped the epitopes of a panel of gH and gL monoclonal antibodies (MAbs), using a series of gH and gL C-terminal truncation variant proteins produced in transiently transfected mammalian cells. Sixteen gH MAbs (including H6 and 37S) reacted with the N-terminal portion of gH between amino acids 19 and 276. One of the gH MAbs, H12, reacted with the middle portion of gH (residues 476 to 678). Nine gL MAbs (including 8H4 and VIII 62) reacted with continuous epitopes within the C-terminal portion of gL, and this region was further mapped within amino acids 168 to 178 with overlapping synthetic peptides. Finally, plasmids expressing the gH and gL truncations were employed in cotransfection assays to define the minimal regions of both gH and gL required for complex formation and secretion. The first 323 amino acids of gH and the first 161 amino acids of gL can form a stable secreted hetero-oligomer with gL and gH792, respectively, while gH323-gL168 is the smallest secreted hetero-oligomer. The first 648 amino acids of gH are required for reactivity with MAbs LP11 and 53S, indicating that a complex of gH648-gL oligomerizes into the correct conformation. The data suggest that both antigenic activity and oligomeric structure require the amino-terminal portions of gH and gL.

Amino Acid Sequence↗

PubMed1998

Requirement of cyclin E-Cdk2 inhibition in p16(INK4a)-mediated growth suppression.

Loss-of-function mutations of p16(INK4a) have been identified in a large number of human tumors. An established biochemical function of p16 is its ability to specifically inhibit cyclin D-dependent kinases in vitro, and this inhibition is believed to be the cause of the p16-mediated G1 cell cycle arrest after reintroduction of p16 into p16-deficient tumor cells. However, a mutant of Cdk4, Cdk4(N158), designed to specifically inhibit cyclin D-dependent kinases through dominant negative interference, was unable to arrest the cell cycle of the same cells (S. van den Heuvel and E. Harlow, Science 262:2050-2054, 1993). In this study, we determined functional differences between p16 and Cdk4(N158). We show that p16 and Cdk4(N158) inhibit the kinase activity of cellular cyclin D1 complexes through different mechanisms. p16 dissociated cyclin D1-Cdk4 complexes with the release of bound p27(KIP1), while Cdk4(N158) formed complexes with cyclin D1 and p27. In cells induced to overexpress p16, a higher portion of cellular p27 formed complexes with cyclin E-Cdk2, and Cdk2-associated kinase activities were correspondingly inhibited. Cells engineered to express moderately elevated levels of cyclin E became resistant to p16-mediated growth suppression. These results demonstrate that inhibition of cyclin D-dependent kinase activity may not be sufficient to cause G1 arrest in actively proliferating tumor cells. Inhibition of cyclin E-dependent kinases is required in p16-mediated growth suppression.

Animals↗

PubMed1998

Immunomodulating functions of recombinant ovine interferon tau: potential for therapy in multiple sclerosis and autoimmune disorders.

The interferons (IFN) are a family of complex proteins possessing antiviral, antiproliferative, and immunomodulatory activities. Two type I recombinant human IFN have been recently approved for the treatment of multiple sclerosis (MS). However, use of high dose type I IFN treatment in MS patients has been limited by dose-related toxicity. Ovine IFN tau is a unique type I interferon discovered for its role in the animal reproductive cycle. It differs from other type I IFNs in that it is remarkably less toxic even at high concentrations, is able to cross species barriers, and is not inducible by viral infection. Ovine IFN tau has been shown to be very effective in the treatment of animal models of MS. In this study, we examined the toxicity of OvIFN tau on human T-cells at high doses and its immunregulatory properties at equivalent doses. Our experiments confirmed the remarkably non-toxic nature of OvIFN tau on human cells at high concentrations as well as immunomodulating properties consistent with other type I IFNs including an antilymphoproliferative effect and inhibition of IFN gamma-induced HLA class II expression. These results suggest that OvIFN tau could be developed into a potentially less toxic therapeutic option for immune-mediated disorders including MS.

Antigen Presentation↗

PubMed1998

A video data base system for studying animal behavior.

Classification of farm animal behavior is based on oral or written descriptions of the activity in which the animal is engaged. The quantification of animal behavior for research requires that individuals recognize and code the behavior of the animal under study. The classification of these behaviors can be subjective and may differ among observers. Illustrated guides to animal behavior do not convey the motion associated with most behaviors. Video-based guides offer a method of quantifying behaviors with real-time demonstrations of the components that make up a behavior. An animal behavior encyclopedia has been developed to allow searching and viewing of defined (video-recorded) behaviors on the Internet. This video data base is being developed to initiate a system that automatically extracts animal motion information from an input animal activity video clip using a multiobject tracking and reasoning system. Eventually, the extracted information will be analyzed and described using standard animal behavior definitions (the behavior encyclopedia). The intended applications of the behavior encyclopedia and video tracking system are 1) an accessible data base for defining and illustrating behaviors for both research and teaching and 2) to further automate the collection of animal behavior data.

Animals↗

PubMed1998

Complement component 1 inhibitor (C1-INH) like protein on murine spermatozoa: anti-C1-INH inhibits in vitro fertilization.

We investigated if complement component 1 inhibitor-like (C1-INH-L) protein found on human spermatozoa exists on mouse spermatozoa and is relevant to reproduction. We used Western blot analysis and immunofluorescence assays to detect C1-INH on murine sperm and tested the effects of the antibodies to C1-INH and albumin (negative control) on in vitro mouse sperm motility and fertilization. C1-INH-L, with molecular weight similar to human C1-INH (100 kDa), was present on the surface of spermatozoan head and midpiece. Treating mouse sperm with anti-C1-INH reduced the mouse sperm motility (P < 0.01), in vitro fertilization (P < 0.01) and embryo development rates (P < 0.01). Anti-albumin failed to do so. We conclude that C1-inhibitor-like protein is present on mouse sperm surface and appears to be relevant to reproduction.

Albumins↗

PubMed1998

The porphyrin photosensitizer Photofrin elevates murine splenic erythropoiesis.

Changes occurring within the spleens of the genetically distinct DBA/1 and DBA/2 mouse strains produced by the photosensitizer Photofrin in the absence of direct light exposure were analyzed. Photofrin significantly increased spleen weight, cellularity and erythroid progenitor levels in both mouse strains tested. The expression of heat stable antigen (HSA), a marker present upon different immature leukocytes as well as certain fully-differentiated cell types including erythrocytes, was increased in the spleens of mice given Photofrin. It was shown for Photofrin-injected DBA/1 mice that a spleen cell population which expressed high levels of HSA also bound the iron transport protein transferrin. Photofrin increases the splenic demand for iron by promoting erythropoietic activity within the tissue.

Animals↗

PubMed1998

Cloning of 1-aminocyclopropane-1-carboxylate (ACC) synthetase cDNA and the inhibition of fruit ripening by its antisense RNA in transgenic tomato plants.

A 1.7 kb fragment of ACC synthetase cDNA, one member of the ACC synthetase multigene family, was amplified from total tomato cDNA through a polymerase chain reaction (PCR) and cloned in E. coli. Restriction mapping and sequencing analysis confirmed its fidelity and correctness. The cloned ACC synthetase gene was then inserted into a binary vector pBin437, in an inverted orientation between the CaMV 35S promoter with duplicated enhancers and the Nos 3' transcriptional termination sequence, to construct an expression vector pBACC. Transgenic tomato plants were obtained by A. tumefaciens-mediated transformation of cotyledons. PCR detection and Southern blot analysis confirmed the integration of the antisense ACC synthetase gene in the transformed tomato genome. The results from RT-PCR of RNAs isolated from transgenic tomato leaves confirmed that antisense ACC synthetase RNA was synthesized in these transgenic plants. The amount of ethylene released from transgenic tomato fruits was reduced significantly to about 30% of that released by non-transformed controls. The inhibition effect of antisense RNA on fruit ripening was observed in transgenic plants and their progeny (T1). The shelf life of transgenic tomato fruits was at least 60 days at room temperature without significant change in hardness and color. After 15-20 days of treatment of the transgenic fruits with ethylene, most of them reached the ripe stage. The antisense ACC synthetase gene was inherited as a single gene in the progenies of transgenic tomatoes determined by T1 progeny analysis, consistent with the results of Southern blot analysis. Transgenic homozygotes expressing antisense ACC synthetase RNA showed prolonged shelf life in the T2 progeny.

Cloning, Molecular↗

PubMed1998

[A study on dose-effect of suppression to gap junctional intercellular communication function by 50-Hz magnetic fields].

OBJECTIVE: To study the relationship between dose of exposure to 50-Hz magnetic field (MF) and its effects of suppression to gap junctional intercellular communication (GJIC) function. METHODS: Lucifer yellow, a kind of fluorescent dye, was led into single CHL cell by iontophoretic injection. Number of dye-coupled cells (DCC) five minutes after injection was used as an indicator for GJIC function. The effects of different intensities and irradiation of MF on GJIC in CHL cells were studied. RESULTS: Suppression to GJIC by 50-Hz MF depended on its flux intensity. Irradiation with lower flux intensity (0.05, 0.2 and 0.4 mT) of the MF for 24 hours could not inhibit GJIC, but that with higher intensity (0.8 and 1.6 mT) could. No "amplitude window" effect was appeared by irradiation with MF at intensities of zero to 1.6 mT. Exposure to MF at a fixed intensity of 0.8 mT for five minutes had no effects, but that for one hour was more than enough to inhibit GJIC, with the most apparent effects for 24-hour exposure. In addition, it was showed that suppression to GJIC was caused by direct action of 50-Hz MF rather then induced electrical field. CONCLUSION: MF of 50-Hz had suppression to GJIC with a dose-effect relationship.

Animals↗