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Biomedical subjects

H Yang

Publications and source records attributed to H Yang.

At least 685 records · Page 38Linked to original sources
PubMed1997

[Clinical analysis of 39 cases of hepatitis E in pregnancy].

OBJECTIVE: To introduce clinical manifestations and treatment of hepatitis E in pregnancy. METHODS: Thirty-nine cases of hepatitis E in pregnancy, were analysed from June. 1992 to Jun. 1994, retrospectively on its epidemiologic characteristics, clinical manifestations and prognosis. RESULTS: The prognosis of sporadic cases of hepatitis E in pregnancy was good and its main complications were premature rupture of membranes, uterine inertia and fetal distress. CONCLUSIONS: Sporadic case is the main form of hepatitis E in pregnancy in Beijing. Active treatment and intensive monitoring would improve its prognosis.

Adult↗
PubMed1997

[Molecular cloning and sequence analysis of glycoprotein D gene of herpes simplex virus 2 strain Sav and wild strain isolated].

OBJECTIVE: To study the difference of structure and function of HSV-2 gD gene among the wild strain, G and Sav strain. So as to provide theoretical basis for future production of HSV-2 vaccine. METHOD: The partial glycoprotein D gene sequence of HSV-2 strain Sav and wild strain isolated from recurred genital herpes simplex were amplified and cloned with PCR. RESULTS: The homology comparison showed that the homology of DNA and amino acid were 99.2% and 99.1% respectively. CONCLUSIONS: There are high homology of HSV-2 gD gene among the wild strain G and Sav strains, but some variations existed.

Amino Acid Sequence↗
PubMed1997

[A new method and instrument for brainlocal hypothermia].

A new method and instrument for brainlocal hypothermia have been introduced in this paper. The instrument provides hypothermia to cerebral blood circulation by using cold probe hyperthemia to body venors blood by using electric heater. So it reduces the temperature only local in brain. This therapy system provides a safe and successful method for brain protection in wide clinical application, such as brain injure emergency, cerebrovascular disease therapy, heart operation etc.

Body Temperature↗
PubMed1997

[Study of arginase activity in alveolar macrophages from patients with lung cancer].

Alveolar macrophages (AM) were obtained from 20 patients with primary lung cancer and 20 cases with nonmaligment pulmonary disease by BAL and were incubated in vitro in medium with and without BCG and/or IFN-alpha. Then the cell-free supernatants were harvested. The activity of arginase was assayed. It was found that: arginase was produced spontaneously by AM: The spontaneous production of arginase is lower in AMs from the tumor-bearing segments than either nontumor-bearing segments or AMs from the patients with nonmalignant pulmonary diseases (P < 0, .05). The production of arginase was icreased on AMs from the tumor-bearing segments stimulated with BCG and/or IFN-alpha (P < 0.05 or 0.01). The results suggested that (1) There are some function at defects of tumor. (2) The mechanism of anti-tumor and anti-infection activity of BCG and IFN-alpha may possibly increase the production of arginase of AMs.

Adult↗
PubMed1997

[The effect of root canal irrigation and variance of apical foramen pressure by use of casing aspiration needle system in vitro].

The authors introduced casing aspiration needle system (CANS) to irrigating root canal. The effect of root irrigation on removing canal debris and the variance of apical foramen pressure on extracted teeth were compared between the conventional irrigation and CANS irrigation. The results indicated that the effect of root canal irrigation by CANS was much better than the conventional method (P < 0.01). CANS irrigation didn't produce pressure to apical foramen during root canal irrigation. However, in the conventional method, with irrigation needle inserted deeper and deeper in root cancal the pressure of apical foramen gets higher and higher.

Humans↗
PubMed1997

Immunophenotyping fish-to-mouse islet xenograft rejection: a time course study.

UNLABELLED: Tilapia islets, Brockmann bodies (BBs), transplanted under the kidney capsule (KC) of diabetic nude mice provide long-term normoglycemia, but, when transplanted into euthymic mice, reject in about one week. OBJECTIVES: The present study characterizes the cellular infiltrates at several time points during the xenograft rejection process. METHODS: Tilapia BBs were harvested, fragmented, cultured overnight, and then transplanted under the KC of streptozotocin-diabetic Balb/c mice. Glucose levels were measured daily until the mice were killed at 1 (n = 2), 2 (n = 2), 3 (n = 3), and 5 days (n = 3) post transplantation and at the time of BB graft rejection (n = 6). Serial frozen sections of graft-bearing kidneys were stained for murine macrophages (MOMA-2, F4/80, M170), CD4+ (L3T4) T-cells (YTS 191.1), and CD8+ (Ly-2) T-cells (YTS 169.4) by indirect immunoperoxidase; the presence of granulocytes and plasma cells was assessed with H&E stained sections. RESULTS: At 1 day, the grafts have undergone some central necrosis with macrophage infiltration. By 2 days, these changes are very well-developed and granulocytes, almost exclusively eosinophils, begin to surround the graft. At 3 days, rare CD4+ and CD8+ T-cells are seen at the graft kidney interface. Macrophages massively infiltrate the necrotic foci and pepper the graft. At 5 days and at rejection, macrophages and eosinophils predominated in the center of rejecting grafts while CD8+ T-cells and CD4+ T-cells were present at the periphery. Plasma cells were rare. CONCLUSION: We conclude that cell-mediated processes and eosinophils play roles in the rejection of cellular xenografts across this very wide phylogenetic barrier.

Animals↗
PubMed1997

Tilapia Brockmann Bodies: an inexpensive, simple model for discordant islet xenotransplantation.

Brockmann bodies (BBs), large anatomically discrete islet organs found in some teleost fish, are much more easily harvested than pancreatic islets from mammalian donor sources. Tilapia islets, when transplanted into streptozotocin-diabetic athymic nude mice, will produce long-term normoglycemia and mammalian-like glucose tolerance profiles. Our laboratory has used tilapia BBs as an inexpensive model for studying islet xenograft rejection between discordant species. When transplanted into immunocompetent diabetic mice, tilapia BBs reject in roughly 7-8 days. Results to date suggest that tilapia islets are very immunogenic and that encapsulation is necessary to achieve long-term function in euthymic recipients. Continuous, high-dose immunosuppression using 15-DSG is also effective but causes lethal bone marrow suppression. Less aggressive immunosuppression regimens have achieved only modest prolongation of mean graft survival time. Thus far, immunomodulation techniques and transplantation into immune-privileged sites have been ineffective at prolonging graft survival. Tilapia islets currently represent an excellent, inexpensive donor source for discordant islet xenotransplantation studies. In the not distant future, encapsulated islets harvested from transgenic tilapia bearing humanized tilapia insulin genes may also play a role in establishing clinical islet xenotransplantation as a useful treatment modality for type I diabetes mellitus.

Animals↗
PubMed1996

Insertion of metal-responsive elements increases the inducibility of the mouse mammary tumor virus promoter.

The promoter of the mouse mammary tumor virus (MMTV) is commonly used in inducible mammalian expression vectors. We have modified this promoter by inserting metal-responsive elements (MRE) at different sites. Surprisingly, MMTV promoters containing MRE 5' with respect to the glucocorticoid responsive elements (GRE), were not induced by metal ions. However, in the simultaneous presence of dexamethasone and metal ions, the modified promoters displayed a significantly increased transcriptional strength [up to sevenfold more than wild-type (wt) MMTV] in transiently transfected cells and permanent cell lines. This increment in the inducible expression was achieved without a concomitant increase in the basal level of expression. These modified MMTV promoters will offer the opportunity to develop tightly regulated inducible mammalian expression systems that are significantly more potent than the ones based on the wt MMTV promoter.

Animals↗
PubMed1996

Tissue immunogenicity: the role of MHC antigen and the lymphocyte costimulator B7-1.

Pancreatic islet transplantation represents a potential treatment for insulin-dependent diabetes mellitus. One approach to circumvent the requirement for recipient immune suppression is to reduce or eliminate the immunogenicity of the donor graft prior to transplantation. In this study, we have examined the relative contributions of graft MHC Ag expression and donor-derived costimulatory (CoS) activity to the rejection of islet allografts. Depletion of donor hemopoietic APCs from islet tissue facilitated long-term allograft survival even when donor class I MHC Ag expression was greatly increased by IFN-gamma treatment prior to grafting. Conversely, islet allografts from transgenic mice expressing the CoS molecule B7-1 (CD80) on islet beta cells were acutely rejected even when hemopoietic APCs were eliminated. Thus, B7-1 is sufficient to confer the capacity of islet parenchymal cells to stimulate allorejection. Taken together, these results point towards donor-derived CoS activity as a primary target of intervention therapy to modulate tissue immunogenicity.

Animals↗
PubMed1996

Differential effects of macrophage- and granulocyte-macrophage colony-stimulating factors on cytokine gene expression during rat alveolar macrophage differentiation into multinucleated giant cells (MGC): role for IL-6 in type 2 MGC formation.

Macrophage colony-stimulating factor (M-CSF) and granulocyte-macrophage (GM)-CSF stimulate the differentiation of rat alveolar macrophages (AM) into multinucleated giant cells (MGC) with distinct phenotypes (type 1 and type 2 MGC). In the present study, we analyzed the profile of cytokine gene expression induced respectively, by M-CSF and GM-CSF during rat AM differentiation using reverse transcription-PCR. Enhanced mRNA expression for IL-1alpha, TNF-alpha, and TGF-beta1 was observed 3 h after treatment with M-CSF (50 U/ml) or GM-CSF (50 U/ml). In contrast, IL-6 mRNA expression was increased by GM-CSF but not M-CSF. Kinetic analysis indicated that GM-CSF stimulated IL-6 expression early (1.5 h), with maximal effect observed at 24 h and up to 5 days thereafter. Increased mRNA levels for IL-6 were associated with higher IL-6 activity in the culture media of differentiating AM. IL-6 activity was stimulated 3 h after treatment with GM-CSF and increased with time (up to 5 days). Interestingly, addition of exogenous IL-6 (20-100 ng/ml) alone or in combination with GM-CSF to AM cultures increased slightly and selectively the formation of MGC with type 2 phenotype. Conversely, neutralization of endogenous IL-6 during AM differentiation into MGC inhibited significantly (up to 50%) the formation of type 2 MGC. These results suggest a role for IL-6 in the formation of type 2 MGC and provide some insights into the mechanisms of MGC formation and the processes that regulate it positively.

Animals↗
PubMed1996

A functional interleukin 12 receptor complex is composed of two beta-type cytokine receptor subunits.

We have identified a cDNA from a human phytohemagglutinin-activated lymphoblast library encoding a protein that binds 125I-labeled human interleukin 12 (125I-huIL-12) with a Kd of about 5 nM when expressed in COS-7 cells. When coexpressed in COS-7 cells with the previously identified IL-12 beta receptor (IL-12R beta) protein, two classes of 125I-huIL-12 binding sites were measured with Kds of about 55 pM and 8 nM, corresponding to the high- and low-affinity binding sites seen on phytohemagglutinin-activated lymphoblasts. This newly identified huIL-12R subunit is a member of the cytokine receptor superfamily, with closest resemblance to the beta-type cytokine receptor gp130 and the receptors for leukemia inhibitory factor and granulocyte colony-stimulating factor. Consequently, we have reclassified the previously identified IL-12R beta subunit as huIL-12R beta 1 and designated the newly identified subunit as huIL-12R beta 2. huIL-12R beta 2 is an 862-amino acid type I transmembrane protein with a 595-amino-acid-long extracellular domain and a cytoplasmic tail of 216 amino acids that contains three tyrosine residues. A cDNA encoding the mouse homolog of the huIL12R beta 2 protein has also been isolated. Human and mouse IL-12R beta 2 proteins show a 68% amino acid sequence identity. When expressed in COS-7 cells, huIL-12R beta 2 exists as a disulfide-linked oligomer with an apparent monomeric molecular weight of 130 kDa. Coexpression of the two identified IL-12R subunits in Ba/F3 cells conferred IL-12 responsiveness, and clones of these cotransfected Ba/F3 cells that grew continuously in the presence of IL-12 were isolated and designated LJM-1 cells. LJM-1 cells exhibited dose-dependent proliferation in response to huIL-12, with an ED50 of about 1 pM huIL-12. Interestingly, Ba/F3 cells transfected with IL-12R beta 2 alone proliferated in response to huIL-12 with an ED50 of about 50 pM, although a role for endogenous mouse IL-12R beta 1 in IL-12 signal transduction in these transfectants cannot be ruled out. These results demonstrate that the functional high-affinity IL-12R is composed of at least two beta-type cytokine receptor subunits, each independently exhibiting a low affinity for IL-12.

Amino Acid Sequence↗
PubMed1996

Phenotypic segregation of Aedes aegypti for immune antibacterial activity and resistance to filariae.

We report the phenotypic selection of two lines of Aedes aegypti, from a filariae susceptible parental stock (Refm). This selection was based upon the level of inducible anti-gram negative Escherichia coli activity within the haemolymph following E. coli infection. These lines, denoted 'high' and 'low', demonstrated significant differences in anti-E. coli responses throughout. However no difference was observed in the anti-gram positive Micrococcus luteus response following E. coli challenge. F4, F6 and F9 mosquitoes were experimentally infected with Brugia pahangi microfilariae. Reductions of between 53 and 82% in the mean number of larvae completing development in the 'high' compared with the 'low' responding line were observed. Corresponding reductions of between 30 and 50% in the mosquito infection rates also occurred between these lines. These reductions were significant for trials on the F6 and F9 generations. We have therefore selected for Ae. aegypti possessing significant refractoriness to filaria infection. Importantly, this 'high' line has not been exposed to selection pressure using filariae development as a phenotypic selective marker.

Aedes↗
PubMed1996

Positive and negative regulation of a sterol biosynthetic gene (ERG3) in the post-squalene portion of the yeast ergosterol pathway.

Regulation of sterol biosynthesis in the terminal portion of the pathway represents an efficient mechanism by which the cell can control the production of sterol without disturbing the production of other essential mevalonate pathway products. We demonstrate that mutations affecting early and late steps in sterol homeostasis modulate the expression of the ERG3 gene: a late step in sterol biosynthesis in yeast. Expression of ERG3 is increased in response to a mutation in the major isoform of HMG CoA reductase which catalyzes the rate-limiting step of sterol biosynthesis. Likewise, mutations in non-auxotrophic ergosterol biosynthetic genes downstream of squalene production (erg2, erg3, erg4, erg5, and erg6) result in an up-regulation of ERG3 expression. Deletion analysis of the ERG3 promoter identified two upstream activation sequences: UAS1 which when deleted reduces ERG3 gene expression 3-4-fold but maintains sterol regulation and UAS2, which when deleted further reduces ERG3 expression and abolishes sterol regulation. The recent isolation of two yeast genes responsible for the esterification of intracellular sterol (ARE1 and ARE2) has enabled us to directly analyze the relationship between sterol esterification and de novo biosynthesis. Our results demonstrate that the absence of sterol esterification leads to a decrease in total intracellular sterol and ERG3 is a target of this negative regulation.

Acyltransferases↗
PubMed1996

Regulation of neuromodulatory actions of angiotensin II in the brain neurons by the Ras-dependent mitogen-activated protein kinase pathway.

Angiotensin II (Ang II) stimulates norepinephrine transporter (NET) and tyrosine hydroxylase (TH) in the neurons, but the signal transduction mechanism of this neuromodulation is not understood. Treatment of neuronal cultures of hypothalamus-brainstem with Ang II resulted in a time- and dose-dependent activation of Ras, Raf-1, and mitogen-activated protein kinase. This activation was mediated by the interaction of Ang II with the AT1, receptor subtype and was associated with the redistribution of AT1 receptor with Ras and Raf-1 on the neuronal membrane. Treatment with antisense oligonucleotide (AON) to mitogen-activated protein kinase decreased mitogen-activated protein kinase immunoreactivity by 70% and attenuated Ang II stimulation of c-fos, NET, and TH mRNA levels. This demonstrates that induction of these genes requires mitogen-activated protein kinase activation by Ang II. In contrast, AON to mitogen-activated protein kinase failed to inhibit Ang II stimulation of plasminogen activator inhibitor-1 mRNA levels. These results suggest that AT1 receptors are coupled to a Ras-Raf-1 mitogen-activated protein kinase signal transduction pathway that is responsible for stimulation of NET and TH, two neuro-modulatory actions of Ang II in the brain.

Angiotensin II↗