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Biomedical subjects

X Xu

Publications and source records attributed to X Xu.

At least 523 records · Page 29Linked to original sources
PubMed1999

[Development of air microbe sampler with micropore filter membrane].

Dual head air microbe sampler with a large flow capacity of 100 liters per minute was manufactured. The sampler possesses simple structures, light weight, convenient operation and higher sampling efficiency, equal to 77%-96% of the grade six Anderson sampler. Sampling time is a main factor affecting sampling efficiency. This device is suitable for the determination of degree of biological clean air in clean environment and the detection of the pathogenic microbes in ward and public places and also microbes in ordinary environment.

Air Microbiology↗
PubMed1999

[Clinical and pathological analysis in 327 cases with renal biopsy].

The renal biopsy results of 372 cases are summarized in this article. Definite pathological diagnoses were made in 354 cases, among which most cases were of mesengioproliferative glomerulonephritis type (27.1%), followed by glomerulopathy type with minimal change(12.4%). The association between clinical manifestation and pathological change was discussed. The data indicate that renal biopsy plays pivotal role in confirming the clinical diagnosis and guiding treatment.

Adolescent↗
PubMed1999

[Effect of benazepril on renal interstitial inflammatory cell infiltration in rats with unilateral ureteral obstruction].

Effect of benazepril on renal interstitial inflammatory cell infiltration was observed in rats with unilateral ureteral obstruction(UUO). The results showed that the relative volume of interstitium and number of infiltrating inflammatory cell on the fifth day were significantly less in rats with benazepril than the control group, but the difference between two groups lose significance on the tenth day. These data indicate that benazepril can ameliorate early phase of renal interstitial inflammation in UUO.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1999

[Comparison of semi-bionic extraction and water extraction in extraction of chemical constituents from processed cortex Phellodendri].

OBJECTIVE: To Study the granulation of processed Cortex Phellodendri. METHOD: Take berberine, total alkaloids and dry extract as indexes to compare the semi-bionic extraction (SBE) with water extraction (WE). RESULT: In 5 kinds of phellodendron bark solution, berberine, total alkaloids and dry extract obtained by SBE are much better than those obtained by WE. CONCLUSION: In the preparation of oral granules from processed Cortex Phellodendri, SBE is superior to WE, when the pH value is adjusted by HCl solution to 1.0 in the first decoction, adjusted by saturated Ca(OH)2 solution to 7.0 in the second decoction and to 10.0 in the third decoction respectively.

Alkaloids↗
PubMed1999

[Establishment and differentiation of murine EG cell lines derived from primordial germ cells].

Primordial germ cells (PGC) were isolated from 8.5, 10.5, 12.5 days post coitum (dpc) embryos of F1 (Balb/c x ICR), C57BL/6J, 129/svJ, 129/sv-ter mice, and cultured on mitotically inactive MEF or STO feeder layer cells with addition of leukemia inhibitory factor, stem cell factor and basic fibroblast growth factor in cultures. PGCs formed densely packed and AKP positive colonies with pluripotential marker gene (oct-4) expression resembling undifferentiated ES cells in morphology and growth pattern. Five EG cell lines derived from PGCs were established: EG1(8.5 dpc, F1), EG2 and EG3 (8.5 dpc, C57BL/6J), EG4 (10.5 dpc, 129/svJ), EG5 (10.5 dpc, 129/sv-ter). No long term culture was obtained from 12.5 dpc PGCs of 29 embryos. All five EG cell lines cultured on feeder layer cells or in LIF containing medium still remain undifferentiated state at 15 th passage. Under appropriate conditions, EG cells formed embryoid bodies in suspension culture and multiple types of differentiated cells in monolayer culture. When these EG cells were injected in nude mice, they formed teratocacinomas containing differentiated cells such as cartilage, neural tissue and epithelium. These results show that EG1-5 cell lines derived from 8.5, 10.5 dpc embryos are pluripotential.

Animals↗
PubMed1999

[Temperature effect and temperature gradient technology in capillary electrophoresis].

A review is given here to describe the temperature effect and temperature gradient technology in capillary electrophoresis (CE). The temperature effects on the analysis of DNA, protein peptides and amino acids, enantiomers, carbohydrates and other substances are discussed respectively. The theory of temperature effect is also mentioned. The importance of the temperature gradient in CE, the classifications of gradient technology in CE, the potential applications and different method development of the temperature gradient are described. Fifty-one references are cited.

Amino Acids↗
PubMed1999

[Study on the steroid constituents of soft coral Lobophytum microspiculatum].

The soft coral Lobophytum microspiculatum collected from Xisa Islands of the South China Sea was immersed in and extracted with ethyl alcohol and the extract was concentrated, and then partitioned between ethyl acetate and water. The portion soluble in ethyl acetate was subjected to column chromatography over Sillca H, eluted with a step gradient of EtOAc and petroleum ether. The sterols were obtained from 20% EtOAc-petroleum ether eluent portion. By means of GC/MS method, the sterols were identified to be: cholesta-26-methyl-ol; ergosta-8, 22-dien-3 beta-ol, 24-methyl; ergosta-5, 22-dien-3 beta-ol, 23, 24-dimethyl; cholesta-5,22(23)-dien-3 beta-ol, 22,24-dimethyl; cholesterol; ergosta-5,22-dien-3 beta-ol, 24-methyl; ergosta-5,22-dien-3 beta-ol, 22,24-dimethyl, 24-methyl-cholesterol; ergosta-7-en-3 beta-ol, 24-methyl; nor-ergosta-7-en-3 beta-ol and gorgosterol. Among them cholest-5,22(23)-3 beta-ol, 22,24-dimethyl (4) is a new compound which was found at the first time from the nature. This finding gave a further prove for the biogenesis path way of gorgosterol.

Animals↗
PubMed1999

[Establishment and identification of the monoepitopic monoclonal antibody of Plasmodium falciparum].

AIM: To prepare a monoepitopic monclonal antibody of Plasmoduim falciparum. METHODS: According to the theory of protein structure, a peptide with 6-9 residues representting the antigenicity of the original histidine-rich protein II (HRP-II) of P. falciparum was synthesized and used to immunize BALB/c mice after purity identification by capillary electrophoresis. RESULTS: Four hybridoma cell lines targeting a suitable peptide from pf HRP-II were obtained by using spleen embedment method and hybridoma technology. CONCLUSION: It is the first report to prepare a monoepitopic monoclonal antibody against original protein by selecting a suitable peptide from the primary sequence of protein.

Animals↗
PubMed1999

[Isolating, cloning, and sequencing of HPV16E6E7 gene from a cervical carcinoma biopsy in Shandong Province].

OBJECTIVE: In order to study the structure specificity of HPV16E6E7 gene of a Chinese patient of cervical carcinoma in Shandong province. METHODS: The tissue DNA were abstracted from cervical carcinoma biopsies and the type of HPV was identified by HPV multiple primers PCR. HPV16E6E7 gene was amplified by PCR from the cervical carcinoma tissue DNA with the infection of HPV16 type only, and then cloned the E6E7 gene into pALTERI vector. After sequencing the double strand, the gene was compared with the prototype E6E7 gene of HPV16. RESULTS: A new recombinant plasmid was constructed and named HPV16E6E7-SD. Sequencing results showed one mutation in HPV16E6E7-SD, the 557th neocleotide in the viral neocleotide sequence "T" was changed into "C", and caused the termination cordon TAA of E6 gene to convert into a Gln cordon CAA. CONCLUSIONS: There is a structure difference between HPV16E6E7-SD and the standard strain.

Base Sequence↗
PubMed1999

[Karyotype analysis of Carpesium cernuum].

The paper reported the chromosome number, karyotype and chromosome volume of Carpesium cernuum. The normal diploid was 2n = 40, karyotype formula based on Levan's publication was k(2n) = 40 = 24 m + 12 sm + 2 st + 2T. According to the method of S. R. Kuo, the chromosome relative length was 2n = 40 = 8L + 6M2 + 16M1 + 10S, which belong to "2B" type according to the Stebbins' karyotype classification. The AS.K% was 62.35% from Arano's method. The total volume of chromosome groups was 13.76 microns 3.

Asteraceae↗
PubMed1999

[Nucleotide sequence of A/Goose/Guangdong/2/96 (H5N1) virus M and NS RNA].

OBJECTIVE: To determine the nucleotide sequences of M and NS genes of A/Goose/Guangdong/2/96(H5N1) virus and also to compare them with the sequences of A/HK/156/97(H5N1) strain for revealing the relationship between the two viruses, as well as for setting up a solid base for studying M and NS genes of influenza A viruses in the future. METHODS: Virion RNA was transcribed into cDNA by reverse transcriptase, cDNA was amplified by PCR, the products of PCR were purified. Afterward, RNA sequence analysis was performed by the dideoxynucleotide chain termination method using synthetic oligodeoxynucleotide primers. RESULTS: The segment length of A/Goose/Guangdong/2/96(H5N1) virus RNA 7 is 1,027 nucleotides. It codes M1 (252 amino acids) and M2 (97 amino acids) proteins. However, the segment length of RNA 8 of A/Goose/Guangdong/2/96(H5N1) virus is 890 nucleotides coding NS1 (230 amino acids) and NS2 (121 amino acids) proteins. The amino acid sequence homologies of M1, M2, NS1 and NS2 protein molecules between A/Goose/Guangdong/2/9(H5N1) and A/HK/156/97 (H5N1) viruses are 97.6%, 92.8%, 65.7% and 76.9%, respectively. CONCLUSION: The lengths of A/Goose/Guangdong/2/96(H5N1) virus RNA 7 and RNA 8 and 1,027 are 890 nucleotides, respectively. These two RNA segments belong to those of avian influenza A virus. The A/HK/156/97(H5N1) virus RNA 7 and RNA 8 segments are not derived from those of A/Goose/Guangdong/2/96(H5N1) virus directly.

Amino Acid Sequence↗
PubMed1999

The diagnosis and treatment of gastrinoma: report of 17 cases.

OBJECTIVE: To study the experience of diagnosis and treatment of gastrinoma. METHODS: A retrospective study of 17 patients with gastrinoma seen from 1978 through 1998 in PUMC hospital. RESULTS: Three of the 17 cases were associated with multiple endocrine neoplasia type I (MEN-I) syndrome. Tumors dispersed extensively in pancreas (31%), duodenum (25%), lymphnode (19%) and other place (25%). Ultrasonography and computed tomography (CT) were sensitive in localizing tumor in pancreas and liver, but were not so well for small tumor in duodenum and lymph node. The angiography, percutaneous transhepatic portal sampling (PTPS), scintigraphy and endoscopic ultrasonography (EUS) also can be used. Sixteen of 17 patients underwent 38 operations and 56 percent of the 16 cases underwent several operations. Seven patients at last performed total gastrectomy that was still considered as a choice of treatment. Tumor resection was rare because the advancing of tumor in most cases. CONCLUSIONS: Diagnosing gastrinoma in its early stage and striving for the tumor resection and reducing the metastasis of liver were the cruxes for good prognosis.

Adolescent↗
PubMed1999

[Induction of osteointegration of rabbit mandibular central fissure with guided tissue regeneration]

OBJECTIVE:To observe the effect of guided tissue regeneration (GTR) on induction of ostegenesis in developmental bone clefts,and provide a basis for the use of GTR to repair bony clefts in cleft lip and palate patients.METHODS:The e-PTFE membrane was placed on the labial and lingual sides of the rabbit mandibular central fissure.A radiological and pathological study was performed to determine the healing of the fissure integration.RESULTS:The results showed that the bony cleft was completely integrated 4 weeks after placement of the barrier membrane.CONCLUSION:GTR is an effective approach to reconstruct bony cleft,and is likely to be used in repair of alveolar cleft and cleft palate.

Journal Article↗
PubMed1999

Kinin-mediated coronary nitric oxide production contributes to the therapeutic action of angiotensin-converting enzyme and neutral endopeptidase inhibitors and amlodipine in the treatment in heart failure.

Increasing evidence suggests that angiotensin-converting enzyme (ACE) inhibitors can increase vascular nitric oxide (NO) production. Recent studies have found that combined inhibition of ACE and neutral endopeptidase (NEP) may have a greater beneficial effect in the treatment of heart failure than inhibition of ACE alone. Amlodipine, a calcium channel antagonist, has also been reported to have a favorable effect in the treatment of patients with cardiac dysfunction. The purpose of this study was to determine whether and the extent to which all of these agents used in the treatment of heart failure stimulate vascular NO production. Heart failure was induced by rapid ventricular pacing in conscious dogs. Coronary microvessels were isolated from normal and failing dog hearts. Nitrite, the stable metabolite of NO, was measured by the Griess reaction. ACE and NEP inhibitors and amlodipine significantly increased nitrite production from coronary microvessels in both normal and failing dog hearts. However, nitrite release was reduced after heart failure. For instance, the highest concentration of enalaprilat, thiorphan, and amlodipine increased nitrite release from 85 +/- 4 to 156 +/- 9, 82 +/- 7 to 139 +/- 8, and 74 +/- 4 to 134 +/-10 pmol/mg (all *p <.01 versus control), respectively, in normal dog hearts. Nitrite release in response to the highest concentration of these two inhibitors and amlodipine was reduced by 41% and 31% and 32% (all #p <.01 versus normal), respectively, in microvessels after heart failure. The increase in nitrite induced by either ACE or NEP inhibitors or amlodipine was entirely abolished by Nw-nitro-L-arginine methyl ester, HOE 140 (a B2-kinin receptor antagonist), and dichloroisocoumarin (a serine protease inhibitor) in both groups. Our results indicate that: 1) there is an impaired endothelial NO production after pacing-induced heart failure; 2) both ACE and NEP are largely responsible for the metabolism of kinins and modulate canine coronary NO production in normal and failing heart; and 3) amlodipine releases NO even after heart failure and this may be partly responsible for the favorable effect of amlodipine in the treatment of heart failure. Thus, the restoration of reduced coronary vascular NO production may contribute to the beneficial effects of these agents in the treatment of heart failure.

Amlodipine↗
PubMed1998

The N-terminal domain of RGS4 confers receptor-selective inhibition of G protein signaling.

Regulators of heterotrimeric G protein signaling (RGS) proteins are GTPase-activating proteins (GAPs) that accelerate GTP hydrolysis by Gq and Gi alpha subunits, thus attenuating signaling. Mechanisms that provide more precise regulatory specificity have been elusive. We report here that an N-terminal domain of RGS4 discriminated among receptor signaling complexes coupled via Gq. Accordingly, deletion of the N-terminal domain of RGS4 eliminated receptor selectivity and reduced potency by 10(4)-fold. Receptor selectivity and potency of inhibition were partially restored when the RGS4 box was added together with an N-terminal peptide. In vitro reconstitution experiments also indicated that sequences flanking the RGS4 box were essential for high potency GAP activity. Thus, RGS4 regulates Gq class signaling by the combined action of two domains: 1) the RGS box accelerates GTP hydrolysis by Galphaq and 2) the N terminus conveys high affinity and receptor-selective inhibition. These activities are each required for receptor selectivity and high potency inhibition of receptor-coupled Gq signaling.

Amino Acid Sequence↗
PubMed1998

Interleukin-13: central mediator of allergic asthma.

The worldwide incidence, morbidity, and mortality of allergic asthma are increasing. The pathophysiological features of allergic asthma are thought to result from the aberrant expansion of CD4(+) T cells producing the type 2 cytokines interleukin-4 (IL-4) and IL-5, although a necessary role for these cytokines in allergic asthma has not been demonstrable. The type 2 cytokine IL-13, which shares a receptor component and signaling pathways with IL-4, was found to be necessary and sufficient for the expression of allergic asthma. IL-13 induces the pathophysiological features of asthma in a manner that is independent of immunoglobulin E and eosinophils. Thus, IL-13 is critical to allergen-induced asthma but operates through mechanisms other than those that are classically implicated in allergic responses.

Allergens↗
PubMed1998

A targeted disruption of the murine Brca1 gene causes gamma-irradiation hypersensitivity and genetic instability.

Germline mutations of the Brcal gene are responsible for most cases of familial breast and ovarian cancers, but somatic mutations are rarely detected in sporadic events. Moreover, mouse embryos deficient for Brca1 have been shown to die during early embryogenesis due to a proliferation defect. These findings seem incompatible with the tumor suppress function assigned to this gene and raise questions about the mechanism by which Brca1 mutations cause tumorigenesis. We now directly demonstrate that BRCA1 is responsible for the integrity of the genome. Murine embryos carrying a Brca1 null mutation are developmentally retarded and hypersensitive to gamma-irradiation, suggesting a failure in DNA damage repair. This notion is supported by spectral karyotyping (SKY) of metaphase chromosomes, which display numerical and structural aberrations. However, massive chromosomal abnormalities are only observed when a p53-/- background is introduced. Thus, a p53 dependent cell cycle checkpoint arrests the mutant embryos and prevents the accumulation of damaged DNA. Brca1-/- fibroblasts are not viable, nor are Brca1-/-:p53-/- fibroblasts. However, proliferative foci arise from Brca1-/-: p53-/- cells, probably due to additional mutations that are a consequence of the accumulating DNA damage. We believe that the increased incidence of such additional mutations accounts for the mechanism of tumorigenesis associated with Brca1 mutations in humans.

Animals↗