Search PubMed⌕ Search

Biomedical subjects

J Guo

Publications and source records attributed to J Guo.

At least 307 records · Page 17Linked to original sources
PubMed1997

RAGE mRNA expression in the diabetic mouse kidney.

Receptors for advanced glycation end products (RAGE), which bind and internalize AGE-modified proteins formed from oxidation and other products of the nonenzymatic glycation reaction, have been mechanistically implicated in the development of the chronic complications of diabetes. In the present experiments, we sought evidence for the participation of RAGE in diabetic nephropathy by analysis of steady state levels of mRNA encoding RAGE in the renal cortex of a well-defined animal model (the db/db mouse) that develops renal pathology similar to that found in human diabetes. In these animals, increased AGE-product formation was confirmed by measurement of fluorescence in serum and renal cortex proteins. Renal involvement was confirmed by demonstration of increased urine albumin excretion and elevated serum creatinine concentrations relative to nondiabetic (db/m) littermate controls. Despite elevated concentrations of circulating and tissue AGE-modified proteins, the level of RAGE mRNA expression in renal cortex of diabetic mice did not significantly differ from that in nondiabetic littermate controls. The findings militate against changes in RAGE expression in the pathogenesis of renal abnormalities in this animal model.

Albuminuria↗
PubMed1997

Intracerebral recombinant HSV-1 vector does not reactivate latent HSV-1.

Herpes simplex virus type-1 (HSV-1) has been used for gene delivery in the nervous system for the treatment of brain tumors and other neurological diseases. In most protocols, recombinant viruses containing the gene of interest are directly injected into the brain. Since many people harbor latent wild-type HSV-1 virus in sensory ganglia and other regions of the nervous system, there is a potential risk that the injected recombinant virus may reactivate the latent wild-type virus to cause severe encephalitis. The present study used two rat latent infection models to evaluate this risk. Adult rats were infected with wild-type kos by cornea scarification or by intracerebral injection, and after the establishment of latency, the ICP6(-) strain hrR3 was injected intracerebrally. In the control group, the latent virus was reactivated by treatment of cadmium sulfate. Viral shedding from tears was detected by incubation with Vero cells, and the trigeminal ganglia, cortical tissue and the eyes were collected to detect reactivated wild-type virus by RT-PCR. Our results showed that while the reactivated wild-type virus was readily detectable in the cadmium-sulfate-treated animals, intracerebrally infected hrR3 did not reactivate the latent virus in either the corneal model or the cerebral model. These results indicate that intracranial injection of partially defective recombinant virus may bear little risk of reactivating latent wild-type virus harbored in the sensory ganglia or the brain in our animal model.

Animals↗
PubMed1997

Heterogeneous expression of transketolase in ocular tissues.

PURPOSE: Previous studies have shown that transketolase is preferentially expressed in the corneal epithelium and comprises up to 10% of the soluble protein of the mature mouse cornea. The aim of this study is to evaluate the expression and distribution of TKT in the different ocular tissues. METHODS: We have used in situ hybridization and immunohistochemistry to localize TKT mRNA and protein in the developing and adult mouse eye. RESULTS: TKT were found to be widely distributed throughout the adult mouse eye. Among the ocular tissues examined, the corneal epithelium exhibited the highest levels of TKT mRNA and protein. Within the epithelial layer, TKT mRNA and protein were differentially distributed with the highest expression occurring in basal cells and the lowest in apical cells, suggesting that TKT expression in the corneal epithelium may be differentiation-related. Enriched expression of TKT was also found in the cornea endothelium, lens epithelium, ciliary body, and iris. Low basal levels of expression were observed in the limbus and conjunctiva. In contrast to the adult eye, TKT expression in the one-day-old mouse eye was homogeneous at low, but detectable levels, suggesting that TKT expression is developmentally regulated in the cornea as well as in the other ocular tissues. In the healing corneal epithelium, TKT expression in the single cell layer of the leading edge was completely suppressed until the cells began to stratify, at which point TKT expression increased markedly. CONCLUSIONS: The results presented here suggest that TKT is differentially expressed and developmentally regulated in the various tissues that comprise the eye.

Aging↗
PubMed1997

Anti-interleukin (IL)-4 and -IL-5 antibodies downregulate IgE and eosinophilia in mice exposed to Aspergillus antigens.

The effect of multiple divided doses compared with single-dose injections of antibodies to murine interleukin (IL)-4 and IL-5 in their respective downregulation of IgE and eosinophilia developing in a model of allergic aspergillosis is investigated. BALB/c mice were exposed to Aspergillus fumigatus antigens (Af) before and along with anticytokine antibodies. The kinetics of blood eosinophils, eosinophil peroxidase (EPO) in bone-marrow cells, serum levels of IgE and Af-specific antibodies, Af-induced cytokine production and mRNA, and lung histology were studied. The results indicate that only multiple anti-IL-5 antibodies were effective in maintaining baseline levels of blood eosinophils. Multiple anti-IL-4 antibodies also downregulated eosinophils in the bone marrow, lung, and peripheral blood, although to a lesser extent than in anti-IL-5 antibody-injected mice. Significant correlation between the EPO activity and the eosinophil numbers in anticytokine antibody-treated mice was observed. The different anti-IL-4 antibody treatments downregulated IgE to the same extent. We conclude that multiple divided doses of anti-IL-5 antibodies are required to sustain normal eosinophil levels in murine allergic aspergillosis. This information may be significant in the therapy of pulmonary allergic diseases.

Animals↗
PubMed1997

Human immunodeficiency virus type 1 nucleocapsid protein promotes efficient strand transfer and specific viral DNA synthesis by inhibiting TAR-dependent self-priming from minus-strand strong-stop DNA.

During the first strand transfer in reverse transcription, minus-strand strong-stop DNA [(-) SSDNA] is annealed to the 3' end of the acceptor RNA in a reaction mediated by base-pairing between terminal repeat sequences in the RNA and their complement in the DNA. The large stem-loop structure in the repeat region known as TAR could interfere with this annealing reaction. We have developed an in vitro human immunodeficiency virus type 1 (HIV-1) system to investigate the effect of TAR on strand transfer. Mutational analysis demonstrates that the presence of TAR in the donor and acceptor templates inhibits strand transfer and is correlated with extensive synthesis of heterogeneous DNAs formed by self-priming from (-) SSDNA. These DNAs are not precursors to the transfer product. Interestingly, products of self-priming are not detected in HIV-1 endogenous reactions; this suggests that virions contain a component which prevents self-priming. Our results show that the viral nucleocapsid protein (NC), which can destabilize secondary structures, drastically reduces self-priming and dramatically increases the efficiency of strand transfer. In addition, the data suggest that the ability to eliminate self-priming is a general property of NC which is manifested during reverse transcriptase pausing at sites of secondary structure in the template. We conclude that this activity of NC is critical for achieving highly efficient and specific viral DNA synthesis. Our findings raise the possibility that inactivation of NC could provide a new approach for targeting reverse transcription in anti-HIV therapy.

DNA, Single-Stranded↗
PubMed1997

Enhanced downregulation of Lck-mediated signal transduction by a Y114 mutation of herpesvirus Saimiri tip.

Tip of herpesvirus saimiri associates with Lck and downregulates Lck function in cellular signal transduction. In this report, we demonstrate that mutation of tyrosine 114 of Tip significantly increases Lck-binding activity. This mutant exhibits a dramatic increase in the suppression of cellular tyrosine phosphorylation and surface expression of lymphocyte antigens in comparison with wild-type Tip. In addition, the expression of TipY114 converted the transforming morphology of fibroblasts induced by oncogenic F505 Lck to a normal cellular morphology. These results further support a mechanism by which the association of Tip with Lck negatively regulates Lck-mediated signal transduction.

3T3 Cells↗
PubMed1997

Mechanisms of homologous and heterologous desensitization of PTH/PTHrP receptor signaling in LLC-PK1 cells.

Parathyroid hormone (PTH) activates multiple intracellular effectors, including adenylyl cyclase (AC) and phospholipase C (PLC), via a single receptor [PTH/parathyroid hormone-related protein receptor (PTHR)] expressed in bone and kidney. Homologous desensitization of PTHR signaling occurs, but the relative importance of reduced receptor expression vs. impaired receptor-effector coupling in this process remains unclear. It also is not known if AC and PLC responses to PTH are desensitized independently or interdependently. In LLC-PK1 cells that expressed transfected wild-type PTHRs, PTH caused dose- and time-dependent desensitization of both the AC and PLC-responses to PTH without altering PTHR expression. Desensitization of AC was blocked in mutant cells resistant to adenosine 3',5'-cyclic monophosphate but not when cells expressed mutant PTHRs with defective PLC coupling. Desensitization of PLC was unaffected by PKA blockade, partially mimicked by phorbol ester, and not reproduced by agents that selectively activated AC. The finding that homologous PTHR desensitization in LLC-PK1 cells is signal specific suggests that prior exposure of other cells to PTH also may induce discordant regulation of subsequent PTHR signaling, altering the character as well as the intensity of the hormonal response.

Adenylyl Cyclases↗
PubMed1997

Recombinant thyroid peroxidase-specific Fab converted to immunoglobulin G (IgG) molecules: evidence for thyroid cell damage by IgG1, but not IgG4, autoantibodies.

A recombinant autoantibody Fab (SP1.4) to thyroid peroxidase (TPO), cloned from intrathyroidal B cell immunoglobulin genes, interacts with an epitope on TPO recognized by all patients with autoimmune thyroid disease. To compare the biological properties of IgG1 and IgG4 TPO autoantibodies, we converted Fab SP1.4 to full-length immunoglobulins. The SP1.4 heavy and kappa light chain variable region genes, spliced by overlap PCR to a mammalian signal peptide, were transferred to expression vectors for human IgG1, IgG4, and kappa L chains. Plasmids containing the IgG1 (or IgG4) heavy chain and the kappa L chain were cotransfected into SP2/0 mouse myeloma cells. Cells secreting TPO autoantibodies were cloned, and IgG1-SP and IgG4-SP were affinity purified from medium using protein G. Their subclass specificities were confirmed by enzyme-linked immunosorbent assay and fluorometry after binding to Chinese hamster ovary cells expressing cell surface TPO. Further confirmation of SP1.4 Fab conversion to full-length molecules was the ability of protein A to precipitate IgG1-SP and IgG4-SP complexed to [125I]TPO. IgG1-SP1.4, IgG4-SP1.4, and Fab SP1.4 had similar high affinities for TPO (Kd = approximately 2 x 10(-10) mol/L). Complexes of [125I]TPO and IgG1-SP (but not IgG4-SP) bound to peripheral blood mononuclear cells (PBMC), but not to a B cell line. Flow cytometry demonstrated Fc receptors Fc gamma RI, Fc gamma RII, and Fc gamma RIII on PBMC, but only Fc gamma RII on the B cell line. Together, these data indicate that IgG1-SP/TPO complexes bind to either Fc gamma RI on monocytes or RIII on natural killer cells. In assays for antibody-dependent cytotoxicity using PBMC, 51Cr release was higher for thyroid cells preincubated with IgG1-SP (13.4%) than with IgG4-SP (2.5%) or with culture medium alone (-0.7%). No specific 51Cr release was observed when either fibroblasts or Chinese hamster ovary cells expressing cell surface TPO were used as target cells. In conclusion, a human TPO-specific Fab converted to IgG1, but not IgG-4, can mediate cytotoxic effects on human thyroid cells in vitro. These observations support the clinical relevance of TPO autoantibody subclass distribution and emphasize the likelihood that, as opposed to being simple markers of thyroid damage, TPO autoantibodies may play a role in the induction of thyroid dysfunction in vivo.

Animals↗
PubMed1997

Existence of a low-threshold and sustained inward current in rabbit atrio-ventricular node cells.

Single myocytes were dissociated from the atrio-ventricular (AV) node of rabbit hearts. Spontaneous action potentials of the N or NH type were recorded from the fusiform AV node cells. Under whole-cell voltage clamp, these cells were characterized by the presence of hyperpolarization-activated cation current (I(f)), delayed rectifier K+ current (IK), and L-type Ca2+ current (ICa,L). After blocking I(f) and IK, depolarizing pulses from -80 mV revealed a sustained inward current, which was suppressed by 1 microM nicardipine. The activation threshold of the sustained inward current was around -60 mV and the maximum amplitude was 25.4 +/- 20.1 pA at -40 mV (n = 15). The current was also blocked by 1 microM verapamil. The sustained inward current was not decreased (125 +/- 32% of control, N = 5) by reducing [Ca2+]o from 1.8 to 0.1 mM, while it was nearly suppressed by depleting [Na+]o, differently from ICa,L. We concluded that the nicardipine-sensitive sustained inward current is largely attributable to Ist described in the rabbit sino-atrial node pacemaker cells. I(f) and Ist were not found in rod-shape AV node cells.

Action Potentials↗
PubMed1997

Cytokine profiles of in vivo activated thyroid-infiltrating T cells cloned in the presence or absence of interleukin 4.

We compared Th1 and Th2 cytokines secreted by randomly selected, intrathyroidal CD4+ T cell clones isolated from a patient with Graves' disease using IL-4 + IL-2 versus IL-2 alone. Prior to T cell isolation, PCR of cDNA from the intact thyroid tissue generated IL-4 and IL-10, but not IFN-gamma, products. As controls, IL-4, IFN-gamma and IL-10 cDNA was amplified from stimulated, but not unstimulated, PBMC. All 21 of the nine IL-2 clones and twelve IL-2 + IL-4 clones isolated from the thyroid tissue were CD4+. With the exception of one clone in the IL-2 group, all clones produced IL-10 on stimulation with anti-CD3 and phorbol-12-myristate 13-acetate (PMA) with similar mean values for both groups. The majority of clones in both groups also produced IFN-gamma and IL-4 after stimulation. However, the IL-4:IFN-gamma ratios were significantly higher in clones isolated using IL-2 + IL-4 than in those isolated with IL-2 alone. Furthermore, the distribution of Th1, Th0 and Th2 type clones, defined by their IL-4:IFN-gamma ratios, was also significantly different between those isolated using IL-2 alone and those isolated using IL-2 + IL-4. Of note, although Th0 clones predominated in both groups, Th1 clones were only obtained using IL-2 alone and Th2 clones were only obtained with IL-2 + IL-4. In conclusion, the presence of IL-4 together with IL-2 induces a shift away from a Th1-towards a Th2-response in T cells cloned from in vivo-activated thyroid-infiltrating lymphocytes. This difference in cytokine profile emphasizes that IL-4 is required for cloning T cells representative of a response involving both Th1 and Th2 cells, as occurs in autoimmune thyroid disease.

Adult↗
PubMed1997

[Effects of different intensity endurance training on hypothalamus-pituitary regulatory function].

Effects of different intensity endurance training on several main hormones related to exercise in the rat hypothalamus-pituitary-adrenal axis-gonadal axis were studied. The results indicated that different intensity endurance training played different roles in their synthesis and release. In 36 m/min training group, the reserve of beta-endorphine beta-EP, in hypothalamus-pituitary, the capacity of body stress and aerobic capacity were increased, whereas the stress level in exercise, the luteinizing hormone LH content were decreased as compared with other groups. It is suggested that proper endurance training may elevate the sports capacity in which beta-EP may play an important role in regulating adrenal axis and gonadal axis directly and indirectly.

Animals↗
PubMed1997

[A clinical review of 700 cases of coronary artery bypass grafting].

To assess the changing trends in patients profiles, operative procedures, and the result of coronary artery bypass grafting (CABG) we reviewed the clinical data of 700 consecutive patients who had anisolated CABG (471, 67.3%), CABG combined with left ventricular aneurysm (170, 24.29%), CABG and valve procedures (48, 6.9%), CABG and ventricular septal defect repair (16, 2.3%) at the Fuwai Hospital. The patients were divided into group A (recent three years) and group B (before 1993). The incidence was significantly increased (P < 0.05) in diabetes, hypercholesterolemia, ventricular dysfunction, left main stem coronary artery disease and three vessles lesion. There was a high incidence of hypertension (41.3%), old myocardiac infarction (36.4%), combined left ventricular aneurysm (24.29%) and IABP needed (9.4%), however no significantl difference was notes between the two groups. Internal mammary artery was used in group A (25.6%) and group B (2.6%) (P < 0.005). The hospital mortality (group A, 2.7% and group B, 9.6%) and perioperative myocarial infarction (group A, 3.2% and group B, 9.0%) decreased significantly (P < 0.005). We conclude that despite a high incidence of hypertension, diabetes, hypercholoesterolemia, old myocardial infarction, ventricular dysfunction and diffuse coronary artery disease the patients tolerate CABG surgery well and obtain a good result.

Adult↗
PubMed1997

[Effect of xuezhikang on the treatment of primary hyperlipidemia].

Xuezhikang is a new blood-lipid-regulating medicine. The components of Xuezhikang include HMG-CoA reductase inhibitor (lovastatin), unsaturated fatty acids and many kinds of amino acids. A comparative study on the effects of Xuezhikang and Simvastatin (Zocor) was carried out. One hundred and eight patients with primary hyperlipidemia were randomly divided into two groups. Group 1 consisted of 53 patients, each taking 4 Xuezhikang capsules/day (1.2 g/day) for 8 weeks and group 2 included 55 cases, each taking Zocor 10 mg/day for 8 weeks. At the end of 8 weeks, the lipid levels were compared with those of the baseline in each group. In group 1 serum levels of total cholesterol (TC), low density lipoprotein cholesterol (LDL-C) and triglycerides (TG) were decreased by 23.0%, 28.0% and 28.1% (P < 0.001) respectively and in group 2 they were reduced by 23.3%, 29.5% and 29.5% (P < 0.001) respectively. Serum level of high density lipoprotein (HDL-C) was increased by 5.0% (P > 0.05) with Xuezhikang and 14.3% (P < 0.01) with Zocor, but no significant differences were found between the two groups in TC, LDL-C, TG and HDL-C. The side effects of Xuezhikang were less than those of Zocor. It is suggested that Xuezhikang made in China is a safe, effective and tolerable lipid modulator.

Adult↗
PubMed1997

[A study of multi-channel visual evoked potentials in exotropic children without amblyopia].

OBJECTIVE: To investigate the clinical significance of multi-channel visual evoked potentials (VEPs) in constant exotropic children without amblyopia and the mechanism of exotropia. METHODS: With 14 active cup electrodes, and full and half field stimulation, the checkerboard pattern was reversed and the VEPs were recorded in control and experimental groups. RESULTS: With full field stimulation, the latent period 1 (LP1) of binocular VEPs was not longer and the amplitude N1-P1 (AN1P1) not higher respectively than those of monocular VEPs in experimental group. These properties were different from those of control group. The AN1P1 of non-dominant eye was decreased, and the LP1 of dominant and non-dominant eye was longer in experimental group than that of the control group. There were no significant differences in comparing LP1 and AN1P1 between nasal-retina and temporal-retina of experimental group. CONCLUSIONS: VEPs can provide a scientific basis for abnormal binocular vision in constant exotropia. Although the visual acuity of constant exotropic children is normal, their VEPs are abnormal. Therefore, there might be dysfunction in primary visual cortex. With half field stimulation, there is no suppression of temporal-retina in monocular VEPs of constant exotropic children.

Adolescent↗
PubMed1997

[Chemical constituents of fructus Amomi].

Seven compounds have been isolated from Fructus Amomi. They were identified as bornyl acetate, camphor, borneol, beta-sitosterol, vanillic acid, stearic acid and palmitic acid. The vanillic acid was found in this medicine for the first time. Fifty-seven components were identified from the volatile oil of Fructus Amomi on the basis of GC-MS analysis. Eight components in the volatile oil over 1% in content are bornyl acetate, camphor, borneol, limonene, camphene, myrecene, carene-3 and alpha-terpeneol.

Drugs, Chinese Herbal↗
PubMed1997

[Comparison of 4 extraction methods of chemical constituents in medicinal tea sishen chaji].

Four extraction method for the medicinal tea Sishen Chaji, were compared with psoralen, schizandrin B and evodiamine taken as indexes. The result shows that the total contents of the three compounds decrease progressively in the following order: semi-bionic extraction, semi-bionic extraction by precipitation with alcohol, extraction with water, and extraction with water and precipitation with alcohol.

Cyclooctanes↗
PubMed1997

Expression of HBV Pre S1 peptide in E. coli and product characterization.

HBV Pre S1 sequence is supposed to play an important role in the infection of HBV. Presence of Pre S1/anti-Pre S1 in serum has valuable clinical implications. In order to improve the study of Pre S1, Pre S1 sequence was overexpressed in E. coli as a fusion protein with MBP (Maltose-binding protein), and anti-Pre S1 antiserum was elicited in rabbits by Pre S1-MBP purified by affinity chromatography. The recombinant plasmid constructed from pMAL-cRI expressed the 106aa Pre S1 sequence at the C terminal of MBP by tac promoter. The resulting protein is about 54 kD in size. Western-blot analysis confirmed its reactivity with antiserum derived from synthetic Pre S1 peptide and serum from patients with acute hepatitis B (AHB). ELISA showed that Pre S1-MBP and Dane particles purified from AHB patient's serum reacted with antiserum against synthetic Pre S1 peptide, and this reaction was specifically inhibited by synthetic Pre S1 peptide. ELISA also demonstrated that antiserum against Pre S1-MBP reacted with synthetic Pre S1 peptide, but not with synthetic HCV peptide or HEV peptide.

Escherichia coli↗