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Biomedical subjects

X Yao

Publications and source records attributed to X Yao.

At least 109 records · Page 6Linked to original sources
PubMed1998

Experimental study on pathogenicity of precore mutants in Hepadnaviridae.

OBJECTIVE: To study the replicative competency and pathogenicity of precore gene mutants of duck hepatitis B virus (DHBV) in the duck model. METHODS: Three site-directed point mutations in the precore region of cloned DHBV were constructed. Head-to-tail dimers were formed. The three plasmids were named: pEDM1-2 (initiation codon ATG mutated to TTG), pEDM2-2 (an "A" was inserted down stream of codon 12, leading to frame shift in the distal end of precore region), pEDM3-2 (codon 38 was changed from TAT to TAA, leading to a stop codon at the 3'-end). Mutants and wild-type cloned DNA dimers were first separately used to transfect LMH cells (a chicken hepatoma cell line) and viruses were collected from supernatant and used to infect 6 one-day-old ducklings per group. Serum duck hepatitis B surface antigen (DHBsAg) and DHBV DNA were assayed. Six weeks after infection, ducks were killed and liver tissues were studied for histopathological changes. RESULTS: After transfection, pEDM1-2, pEDM2-2 and pEDM3-2 expressed similar level of DHBsAg. Replication of pEDM1-2 and pEDM3-2 was similar to that of the wild type clone, while pEDM2-2 replicated at a significantly decreased level. Infection study employing the supernatant of transfected cells was as follows: pEDM1-2 infected 5/6 ducklings, pEDM2-2 non infected, pEDM3-2 infected 2/6 ducklings, wild type virus infected 6/6 ducklings. Positive serum samples from both pEDM1-2 and pEDM3-2 were at a lower serum DHBV level compared to that of the wild type virus. Pathological changes were more significant in pEDM3-2 infected duck livers, with numerous inflammatory cells in portal tract and infiltration into parenchyma. CONCLUSIONS: Mutations in the initiating codon or generation of a stop codon at the 3'-end of the precore region resulted in decreased replication competency of DHBV, while frame-shift mutation of the precore region, covering the epsilon encapsidation signal abolished the replication of DHBV. When the mutants replicated in hosts, more severe pathological changes were observed in ducks infected with mutant harboring a stop codon at the 3'-end. Data suggest that replicative-competent DHBV precore mutant can be more pathogenic than wild-type DHBV.

Animals↗
PubMed1998

[Determination of sunscreen agents in cosmetic products by reversed-phase high performance liquid chromatography].

A method for quantitative determination of eleven sunscreen agents (benzophenone-4,p-amino-benzoic acid, salicylic acid, benzophenone-3,phenyl salicylate, 4-methylbenzylidene camphor, octyl dimethyl p-amino-benzoate, isopropyl dibenzoylmethane, butyl methoxydibenzoylmethane, octyl methoxycinnamate, octyl salicylate) in cosmetic products is described. It was based on a high performance liquid chromatographic separation under the condition of isocratic elution with a mixture solution of methanol-THF-water-70% perchloric acid (200:200:160:0.1) by using a column packed with 10 microns YWG-C15 and UV detection. The recoveries (n = 6) were 94.1%-101% and the relative standard deviations(n = 6) for all eleven sunscreen agents were less than 5%. In addition, the results of analysis of 30 samples out of 103 samples of commercial suntan cosmetics performed are reported in this paper.

Chromatography, High Pressure Liquid↗
PubMed1998

[Influence of interleukin-1 and dexamethasone on prostaglandin production of condylar chondrocytes].

OBJECTIVE: To study the effect of recombinant human interleukin-1(rhIL-1) and dexamethasone on the amount of 6-keto-prostaglandin F1 alpha produced by condylar chondrocytes. METHODS: The concentration of 6-keto-prostaglandin F1 alpha of the chondrocytes supernate was detected respectively at 4, 8, 12, 24, and 72 hours, using the method of radioimmunoassay, after being stimulated by rhIL-1 and dexamethasone for four hours. RESULTS: In normal control group, the concentration of 6-keto-prostaglandin F1 alpha was 1,516.49 ng/L, 1,513.22 ng/L, 1,506.76 ng/L, 1,526.79 ng/L and 2,114.36 ng/L at 4, 8, 12, 24 and 72 hours respectively. In rhIL-1 group, the concentration of 6-keto-prostaglandin F1 alpha was 1,664.32 ng/L at four hours, which was sharply higher than that of the control group(P < 0.01); the concentration of 6-keto-prostaglandin F1 alpha was 1,146.11 ng/L, 949.24 ng/L, 1,392.33 ng/L and 1,481.98 ng/L at 8, 12, 24 and 72 hours respectively, which were sharply lower than that of the control group(P < 0.01). After the condylar chondrocytes were stimulated with dexamethasone for 4 hours, the concentration of 6-keto-prostaglandin F1 alpha decreased more markedly than that of the control group(P < 0.01) throughout the observation period, both in the presence and absence of rhIL-1. CONCLUSION: rhIL-1 could enhance the production of 6-keto-prostaglandin F1 alpha synthesized by condylar chondrocytes. Dexamethasone could inhibit the activity of rhL-1 and the production of 6-keto-prostaglandin F1 alpha synthesized by condylar chondrocytes.

6-Ketoprostaglandin F1 alpha↗
PubMed1998

[An experimental study on the regenerating ability of the condylar cartilage of the rabbit].

OBJECTIVE: To investigate the regenerating ability of the condylar cartilage of the adult rabbit. METHODS: A fullthickness defect was created in the condylar cartilage of the adult rabbit, with or without penetrating into the subchondral bone. RESULTS: In the cases of the condylar cartilage defect without penetration into the subchondral bone, the defects were repaired with fibrous tissue partly. However, in those the defect penetrated the subchondral bone, the defects were repaired with cartilage-like tissue at four and eight weeks periods, then the regenerated tissue transformed into the bone-like tissue. CONCLUSION: The defect of the condylar cartilage can't be repaired with cartilage, and the reparative cells were the undifferentiated mesenchymal cells originated from the bone marrow.

Animals↗
PubMed1998

[A clinical study on reducing immunologic rejection in combining corneal lamellar autografting with allografting].

OBJECTIVE: To reduce the rate of immunologic rejection, corneal lamellar autografting with allografting were combined, making immune cells less attack on allograft. METHODS: The pterygium having encroached upon the pupillary area was removed surgically, and the combination of autograft with allograft was transplanted on the peripheral and central cornea in 23 cases (24 eyes). The control group of 13 cases (13 eyes) was established in which the pterygium and dermoids were removed, and lamellar allografts were transplanted. The rate of rejection and their effects were compared. RESULTS: The rate of transparent autograft and allograft was 100%, no rejection and recurrence of pterygium occurred in any case in the combined group, while in the control group, the rejection rate was 30.8% and recurrence rate, 20.0%. CONCLUSION: The combination of lamellar autografting with allografting can reduce the rate of rejection and recurrence of pterygium.

Adult↗
PubMed1998

[Structural elucidation of the anticoagulation and anticancer constituents from Allium chinense].

Six compounds were isolated from the anticoagulation and anticancer fractions of the bulbs of Allium chinense G. Don. On the basis of chemical evidence and spectral analysis (IR, EI-MS, 1HNMR, 13CNMR, 1H-1H COSY, HMBC, HMQC and NOESY), their structures were established as (25R, S)-5 alpha-spirostane-3 beta-ol 3-O-(beta-D-glucopyranosyl-(1-->2)-[beta-D-glucopyranosyl-(1-->3)]-beta-D- glucopyranosyl-(1-->4)-beta-D-galactopyranoside) (1), (25R, S)-5 alpha-spirostane-3 beta-ol 3-O-(beta-D-glucopyranosyl (1-->2)-[beta-D-glucopyranosyl-(1-->3)](6-acetyl-beta-D-glucopyranosyl)- (1-->4)-beta-D-galactopyranoside) (2), (25R, S)-5 alpha-spirostane-2 alpha, 3 beta-diol 3-O-(beta-D-glucopyranosyl-(1-->2)-O-beta-D-glucopyranosyl-(1-->4)-beta-D- galactopyranoside) (3), (25S)-24-O-beta-D-glucopyranosyl-3 beta, 24 beta-dihydroxy-5 alpha-spirost-3-O-alpha-arabinopyranosyl-(1-->6)-beta-D-glucopyranoside (4), chinenoside II (5) and 2,3,4,9-tetrahydro-1-methyl-1H-pyrido [3,4-b] indole-3-carboxylic acid (6). 4 is a new steroidal saponin, named chinenoside VI. Compounds 1 to 3 are three pairs of steroidal saponin epimers. Among them, the 25S epimer of 2 is first reported, the 25R epimer of 2 and compound 6 were isolated from this title plant for the first time. The relative configuration of compound 6 was firstly determined by NOESY spectrum, and signals of C, H were assigned definitely.

Allium↗
PubMed1997

Structure of the carboxy-terminal fragment of the apo-biotin carboxyl carrier subunit of Escherichia coli acetyl-CoA carboxylase.

The biotin carboxyl carrier protein (BCCP) is a subunit of acetyl-CoA carboxylase, a biotin-dependent enzyme that catalyzes the first committed step of fatty acid biosynthesis. In its functional cycle the biotin carboxyl carrier protein engages in heterologous protein-protein interactions with three distinct partners, depending on its state of posttranslational modification. Apo-BCCP interacts specifically with the biotin holoenzyme synthetase, BirA, which results in the posttranslational attachment of biotin to an essential lysine residue on BCCP. Holo-BCCP then interacts with the biotin carboxylase subunit, which leads to the addition of the carboxylate group of bicarbonate to biotin. Finally, the carboxybiotinylated form of BCCP interacts with transcarboxylase in the conversion of acetyl-CoA to malonyl-CoA. The determinants of protein-protein interaction specificity in this system are unknown. One hypothesis is that posttranslational modification of BCCP may result in conformational changes that regulate specific protein-protein interactions. To test this hypothesis, we have determined the NMR solution structure of the unbiotinylated form of an 87 residue C-terminal domain fragment of BCCP (apoBCCP87) from Escherichia coli acetyl-CoA carboxylase and compared this structure with the high-resolution structure of the biotinylated form that was recently solved by X-ray crystallographic techniques. Although the overall folding of the two proteins is highly similar, small structural differences are apparent for residues of the biotin-binding loop that may be important for mediating specific protein-protein interactions.

Acetyl-CoA Carboxylase↗
PubMed1997

The microtubule-dependent motor centromere-associated protein E (CENP-E) is an integral component of kinetochore corona fibers that link centromeres to spindle microtubules.

Centromere-associated protein E (CENP-E) is a kinesin-related microtubule motor protein that is essential for chromosome congression during mitosis. Using immunoelectron microscopy, CENP-E is shown to be an integral component of the kinetochore corona fibers that tether centromeres to the spindle. Immediately upon nuclear envelope fragmentation, an associated plus end motor trafficks cytoplasmic CENP-E toward chromosomes along astral microtubules that enter the nuclear volume. Before or concurrently with initial lateral attachment of spindle microtubules, CENP-E targets to the outermost region of the developing kinetochores. After stable attachment, throughout chromosome congression, at metaphase, and throughout anaphase A, CENP-E is a constituent of the corona fibers, extending at least 50 nm away from the kinetochore outer plate and intertwining with spindle microtubules. In congressing chromosomes, CENP-E is preferentially associated with (or accessible at) the stretched, leading kinetochore known to provide the primary power for chromosome movement. Taken together, this evidence strongly supports a model in which CENP-E functions in congression to tether kinetochores to the disassembling microtubule plus ends.

Cell Cycle↗
PubMed1997

Association of syntaxin 3 and vesicle-associated membrane protein (VAMP) with H+/K(+)-ATPase-containing tubulovesicles in gastric parietal cells.

H+/K(+)-ATPase is the proton pump in the gastric parietal cell that is responsible for gastric acid secretion. Stimulation of acid secretion is associated with a reorganization of the parietal cells resulting in the incorporation of H+/K(+)-ATPase from a cytoplasmic membrane pool, the tubulovesicle compartment, into the apical canalicular membrane. To better characterize the role of membrane trafficking events in the morphological and physiological changes associated with acid secretion from parietal cells, we have characterized the expression and localization of soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) in these cells. Each of the six different SNARE proteins examined [syntaxins 1 through 4 of 25-kDa synaptosome-associated protein, and vesicle-associated membrane protein] were found to be expressed in parietal cells. Furthermore, two of these SNAREs, vesicle-associated membrane protein and syntaxin 3, were associated with H+/K(+)-ATPase-containing tubulovesicles while the remainder were excluded from this compartment. The expression of syntaxin 1 and synaptosome-associated protein of 25 kDa in parietal cells, two SNAREs previously thought to be restricted to neuroendocrine tissues, suggests that parietal cells may utilize membrane trafficking machinery that is similar to that utilized for regulated exocytosis in neurons. Furthermore, the localization of syntaxin 3, a putative target membrane SNARE, to the tubulovesicle compartment indicates that syntaxin 3 may have an alternative function. These observations support a role for intracellular membrane trafficking events in the regulated recruitment of H+/K(+)-ATPase to the plasma membrane after parietal cell stimulation.

Animals↗
PubMed1997

Functional heterogeneity of parietal cells along the pit-gland axis.

The gastric epithelium forms numerous short pits continuous with long tubular glands divisible into isthmus neck, and base regions. Parietal cells are produced in the isthmus and migrate down to the neck and base regions as they mature and age. Stimulation of parietal cells is manifested by translocation of H(+)-K(+)-adenosinetriphosphatase-rich tubulovesicles (TV) from the cytoplasm into the secretory-apical (SA) membrane. In this study we used rabbit isolated gastric glands to examine the physiological responses of parietal cells to graded levels of stimulation. Quantitative morphometry was used to evaluate parietal cell response along the longitudinal axis of the gland. Acid secretion as estimated by [14C]aminopyrine uptake was well correlated with parallel enzymatic and immunoblot assays for the redistribution of H(+)-K(+)-ATPase from TV to SA membranes. These responses also correlated well with morphological transformations of parietal cells within the isthmus and neck regions of the gastric gland; however, parietal cells in the base of the gland showed very little morphological change in response to any of the stimuli used. The poor responsiveness of basal parietal cells is in agreement with observations of intact mucosa and suggests that older parietal cells may serve some function other than acid secretion.

1-Methyl-3-isobutylxanthine↗
PubMed1997

ME-3407, a new antiulcer agent, inhibits acid secretion by interfering with redistribution of H(+)-K(+)-ATPase.

ME-3407 is a newly developed antiulcer drug that markedly promoted the healing of acetic acid-induced chronic ulcers in rats presumably due to potent inhibition of acid secretion. ME-3407 and its metabolites, the sulfoxide of which was preserved, produced dosedependent inhibition of aminopyrine accumulation by rabbit gastric glands stimulated by any agonist, suggesting that the site of their action was downstream from the production of second messengers. Although one of the metabolites, EF-4025, showed some inhibitory effects on functional activities of H(+)-K(+)-ATPase, ME-3407 itself was not a proton pump inhibitor. ME-3407, but not omeprazole, inhibited the stimulation-associated redistribution of H(+)-K(+)-ATPase from microsomes into the apical membranes in addition to delocalizing ezrin, a putative F-actin-membrane linker, from apical plasma membrane. ME-3407 and EF-4025 inhibited myosin light chain kinase (MLCK) and protein kinase A activities. Because another MLCK inhibitor, wortmannin, showed the same properties as ME-3407, i.e., inhibition of aminopyrine accumulation, inhibition of stimulation-associated redistribution of H(+)-K(+)-ATPase, and abnormal distribution of ezrin, we hypothesize that MLCK is one of the potential targets for the drug. We conclude that ME-3407 is a promising drug for treating peptic ulcers, as well as a useful tool for studying mechanisms of parietal cell activation, especially related to the recruitment and recycling of the proton pump.

Acetic Acid↗
PubMed1997

[Effects of radix Salviae miltiorrhizae on hemodynamics of portal hypertension: clinical and experimental study].

By measuring portal pressure of hepatocirrhotic dogs of bile duct ligation directly, and detecting portal system flow in patients with hepatic cirrhosis by ultrasound doppler, we studied the portal hemodynamic effects of Radix Salviae Miltiorrhizae (RSM). After intravenous administration of RSM in hepatocirrhotic dogs, the portal venous pressure (PPV), wedge hepatic venous pressure (WHVP), and hepatic venous pressure gradient (HVPG) were significantly decreased (P < 0.05-0.01), but the mean arterial pressure (MAP), and heart rate (HR) unchanged (P > 0.05). After long-term administration of RSM (10-12 weeks), the diameter of portal vein (DPV) and splenic vein (DSV), the flow of portal vein (QPV), and splenic vein (QSV) in patients with hepatic cirrhosis were significantly decreased respectively (P < 0.05-0.001). Hypodynamia, abdominal distension, anorexia and liver function (ALT) were improved partially after administration of RSM in patients with hepatic cirrhosis. Side-effects of RSM were not found. The results demonstrated that RSM is an effective drug of depressing portal pressure with few side-effects.

Aged↗
PubMed1997

[Clinical and pathological characteristics in Chinese patients with pauci-immune crescentic glomerulonephritis].

We investigated pauci-immune crescentic glomerulonephritis (PICGN) in Chinese patients, During 11 years (1985-1996), 5,800 patients underwent renal biopsy in Nanjing Jinling Hospital. Eighteen patients were diagnosed as having PICGN. They were 11 women and 7 men with median age of 29 (range 10-71 years). Polyarteritis (33.3%) and polyarteritis nodosa (11.1%) were the secondary diseases. The incidence of PICGN was 0.31% in renal biopsies and 23.10% in crescentic glomerulonephritis. Clinically, most patients (83.3%) showed rapidly progressive nephritis with enlarged kidneys. Gross hemoturia was noted in 61.1% patients, hypertension 44.4%, nephrotic syndrome 44.4%, and oligria 33.3%. However, systemic symptoms were rare except anemia. Pathologically, we observed necrosis of glomerular capillaries (61.1%), infiltration of monocytes and neutrophil cells in glomeruli (44.4%), and vasculitis in interstitium (55.5%), in addition to glomerulosclerosis (44.4%), severe tubular atrophy (83.3%) and interstitial fibrosis (72.2%). Antineutrophil cytoplasmic antibodies (ANCA) was positive in 41.7%. All patients except one received intensively immunosuppressive therapy. 12 patients were subjected to long-term follow up (median 25.9, range 8-72 months). Only three patients were dialysis-dependent, while none died.

Adolescent↗
PubMed1997

[Relationship of C-erbB-2 oncogene overexpression to estrogen progesterone receptors in brease cancer and its prognostic significance].

In order to understand the relationship of C-erbB-2 oncogene overexpression to ER and PR in breast cancer and its prognostic significance, we examined overexpression of C-erbB-2 oncogene in 106 breast carcinomas by using immunohistochemical techniques (LSAB). The results showed that the positive rate of C-erbB-2 overexpression was 63.21% (67/106). The overexpression of C-erbB-2 oncogene related negatively with survival. 81.63% of the cases with overexpression of C-erbB-2 oncogene survived < or = 5 years and 34.29% survived > 10 years. There were significant associations of C-erbB-2 overexpression with advance clinical stage, high histological grade, and positive axillary node status in breast cancers. Negative relationship between hormone receptors and C-erbB-2 oncogene. All of these findings suggested that overexpression of C-erbB-2 oncogene might be an important prognostic factor and the detection of C-erbB-2 oncogene might be arranged as a regular pathological examination in the cases of breast cancer.

Adult↗
PubMed1997

[P53 protein expression in malignant germ cell tumor of ovary and its relationship with clinical course and prognosis].

To study the relationship of P53 protein expression with clinical course and prognosis in malignant germ cell tumor of ovary P53 protein expression was examined by immunohistochemical ABC methods in 82 cases of the neoplasm and 20 cases of normal ovary tissue. The results showed that no expression of P53 protein was detected in normal ovarian tissue. The total expression rate of P53 protein was 24.39% in neoplasm, and the expression was not significantly correlated with the different histological types of neoplasm. The study however found that the protein expression of p53 gene was significantly correlated with the clinical stages and prognosis of the neoplasm.

Choriocarcinoma↗
PubMed1997

[Histopathologic and immunochemical changes in Sjögren's syndrome].

To research into the causes of sjögren's syndrome, we investigated the lacrimal gland tissues of 6 cases of sjogren's syndriome by using electronmicroscopy and immunochemical methods. The results revealed that at the early stage the lacrimal gland cells showed degeneration, irregular arrangement and many intracellular vacuoles. At the middle stage, some lymphocytes infliltrated into the gland tissues. And at the advanced stage, lymphocytes and collagenous fibers were there in substitution of gland cells.

Adult↗
PubMed1997

[Comparative studies on pharmacological and toxic actions of raw fructus Psoraleae and its salt-baked and improved salt-baked products].

The pharmacological and toxic actions of raw Fructus Psoraleae and its salt-baked, and improved salt-baked products were comparatively studied. The leucogenic action of the improved salt-baked product was more effective than that of the original salt-baked one. But no significant difference in antidiarrheal or antiandrogenoid effect was found between the two salt-baked products. The toxicity(LD50 and the injury on kidney) of the improved salt-baked product was lower than that of the salt-baked. one. The results indicate that this improved processing method would contribute to increasing the efficacy and decreasing the toxicity of Fructus Psoraleae.

Androgen Antagonists↗