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Biomedical subjects

L Jin

Publications and source records attributed to L Jin.

At least 235 records · Page 13Linked to original sources
PubMed1999

[Direct, rapid detection for rifampin susceptibility to M. tuberculosis].

OBJECTIVE: To evaluate the use of molecular biotechnology for direct, rapid detection of rifampicin-resistance mutations in M. tuberculosis. METHODS: 45 M. tuberculosis clinical isolates and 70 sputum samples were tested by polymerase chain reaction-single stranded conformation polymorphism (PCR-SSCP) technique. M. tuberculosis strain H37Rv was used as control and compared with the result of susceptibility test. DNA sequencing was also performed in some of the strains. RESULTS: All tested susceptible isolates displayed identical SSCP patterns. Of 29 RFP resistance strains, 26(90%) had distinct mobility shifts that can be discriminated from susceptible isolates. 9 sputum samples which were succeasfully evaluated by PCR-SSCP showed concordant result acquired from BACTEC 460 method. As the result of DNA sequencing, it was observed that seven RFP-resistance phenotype of M. tuberculosis strains had missense mutation, in which 5 isolates displayed TCG-->TTG or CAG mutations at codon 531.2 had CAC-->TAC mutation at codon 526. On the other hand, one strain which was susceptible to rifampin exhibited identical nucleotide alignment to the sequence of rpoB gene. CONCLUSIONS: PCR-SSCP could be used as a method for simple, rapid, and reliable detection of rifampicin-resistance mutations in clinical samples of M. tuberculosis.

Antibiotics, Antitubercular↗
PubMed1999

[Effect of baicalin and tetramethylpyrazine on intracranial hypertension of infectious brain edema in rabbits].

OBJECTIVE: To evaluate the effects of mannitol (MN), baicalin (BC) and tetramethylpyrazine (TMPZ) on intracranial hypertension (ICH) of infectious brain edema induced by Pertussis bacilli (PB) in rabbits. METHODS: Forty-five rabbits were divided randomly into five groups: the normal saline group (A); the pertussis bacilli group (B); the MN treated group (C); the TMPZ treated group (D) and the BC treated group (E). PB was injected into the left internal carotid artery of rabbits to establish the infectious brain edema model, their intracranial pressure (ICP) was monitored continuously by fiberoptic ICP monitor. Treatments were given intravenously 1 hour after injecting PB, and changes of ICP, brain water content (WC), Evans blue (EB), Na+, K+ and morphology were observed within 4 hours after PB or NS injection. RESULTS: MN, TMPZ and BC all could reduce the brain edema and ICH in rabbits induced by PB, the effect of MN was the most rapid and obvious one, but it lasted for rather shorter time, while the effect of TMPZ and BC was initiated later but lasted for a longer time. The ICP of Group C in 2nd to 4th hour was higher than that of Group D and Group E, but lower than that of Group B. The ICP of Group E in 3rd to 4th hour was lower than that of group D. At the same time of lowering ICP, brain WC, EB, Na+ contents and pathologic morphologic change were also alleviated. CONCLUSION: Both BC and TMPZ could reduce ICP in infectious brain edema, the effect of BC was better than that of TMPZ.

Animals↗
PubMed1999

[Clinical protocols for the treatment of severe acute pancreatitis].

OBJECTIVE: To set up principles for the treatment of severe acute pancreatitis (SAP). METHODS: The therapeutic principles and results of SAP in three periods were analyzed. Period I (1980 - 1990) was characterized by early surgical intervention supplemented with integrated traditional and western medical therapy, period II (1991 - 1993) by integrated traditional and western medical therapy supplemented with surgery for early complications, and period III (1994 - 1997) by integrated traditional and western medical therapy supplemented with surgery for local infectious complications only. RESULTS: Because of the improvement of intensive care, the operation rates kept declining in the three periods. They were 77.59%, 54.55% and 29.55% with a mortality rate of 40.52%, 17.17% and 11.36%, respectively. CONCLUSIONS: Integrated traditional and western medicine has been effective in most SAP patients, and surgery is indicated only for late complications such as necrotizing infection. Early surgery should be restricted.

Adolescent↗
PubMed1999

[Effect of triclabendazole on the ultrastructure of body wall and vitelline cells of Paragonimus westermani].

AIM: To observe the ultrastructural changes in the body wall and the vitelline cells of Paragonimus westermani in vitro and in vivo before and after triclabendazole treatment. METHODS: The worms were obtained from in vitro and in vivo tests. All of the samples were processed by conventional techniques, and observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). RESULTS: The external plasma membrane and matrix were cracked or disappeared after the treatment. The necrosis of the muscular layer differed. The cell membranes of cortex and vitelline cells were damaged. Nuclear membrane was damaged partially, heterochromatin solidified and condensed to brim and dissolved. The Golgi complex disappeared, endoplasmic reticulum expanded, mitochodria denatured and dissolved. The damage was more serious in vivo than in vitro. CONCLUSION: Triclabendazole is remarkablely effective against Paragonimus westermani by damaging the body wall and vitelline cells, mainly affecting the nuclei, membrane structures and microtubular system.

Animals↗
PubMed1999

[Fluorimetric study of Tb-EDTA-quercetin and determination of quercetin].

Tb-EDTA-Quercetin complexes were formed under basic conditions. Intramolecular energy transfer occurs in the Tb-EDTA complex with quercetin (QCT) and the terbium (III) ion fluorescence can be sensitized by QCT. Accordingly a fluorimetric method was used for the determination of QCT in urine, serum and mixed substance of rutin-quercetin. The method is simple, sensitive and fast. The linear range is 5.0 x (-7)-1.0 x10(-5) mol x L(-1) and the detection limit is 5.0 x 10(-8) mol x L(-1). This method can be applied to the determination of QCT in non-pretreated urine and serum successfully. The recoveries are in the range of 103%-96%.

Edetic Acid↗
PubMed1999

[The two-step three-photon resonant ionization of atom Cu].

This paper discusses the process of resonant laser ablation (RLA), where the two-step three-photon resonant ionization of copper is considered as the best scheme. The rate equations of resonant ionization of copper are calculated and the factors that affect the ionization efficiency are discussed. The results prove the potential advantages of RLA especially the low energy threshold.

English Abstract↗
PubMed1999

[Study of the fluorescence of terbium-pipemidic acid system and the determination of pipemidic acid in urine and serum].

Intramolecular energy transfer occurs in the terbium complex with pipemidic acid (PPA) and the terbium(III) ion fluorescence can be sensitized by PPA. The fluorescence intensity of the Tb3+-PPA system is proportional to the amount of PPA. Accordingly, a fluorimetric method for the determination of PPA is proposed. The characteristics of the method include low background noise, high selectivity and long fluorescence lifetime. The method can be applied to the determination of PPA in urine and serum. The recovery is in the range of 94.6%-102%. Its detection limit and linear range for PPA are 3.6 ng/mL and 5.0 x 10(-8)-4.0 x 10(-6) mol/L, respectively.

Fluorescence↗
PubMed1998

Molecular cloning and expression of the rat EAAT4 glutamate transporter subtype.

Glutamate transport is a primary mechanism for the synaptic inactivation of glutamate. Excitatory amino acid transporter 4 (EAAT4) is a novel glutamate transporter with properties of a ligand-gated chloride channel that was recently cloned from human brain. Here we report the cloning of rat EAAT4 (rEAAT4) cDNA from rat cerebellum. The nucleotide sequence of rEAAT4 was 88% identical to the human sequence, and the predicted peptide was 89% identical to the human protein. The transport activity encoded by rEAAT4 has high affinity for L-glutamate. In Xenopus laevis oocytes expressing rEAAT4, L-glutamate and other transporter substrates elicited a current predominantly carried by chloride ions. Like human EAAT4, the rEAAT4 mRNA was largely restricted to cerebellar Purkinje cells; the rEAAT4 protein was localized to Purkinje cell somas and dendrites.

Amino Acid Transport System X-AG↗
PubMed1998

Structural and functional properties of two mutants of lecithin-cholesterol acyltransferase (T123I and N228K).

Two naturally occurring mutants of human lecithin-cholesterol acyltransferase (LCAT), T123I and N228K, were expressed in COS-1 and Chinese hamster ovary cells, overproduced, and purified to homogeneity in order to study the structural and functional defects that lead to the LCAT deficiency phenotypes of these mutations. The mutants were expressed and secreted by transfected cells normally and had molecular weights and levels of glycosylation similar to wild type LCAT. The purified proteins (>98% purity) had almost indistinguishable structures and stabilities as determined by CD and fluorescence spectroscopy. Enzymatic activities and kinetic analysis of the pure enzyme forms showed that wild type LCAT and both mutants were reactive with the water-soluble substrate, p-nitrophenyl butyrate, indicating the presence of an intact core active site and catalytic triad. Both the T123I and N228K mutants had markedly depressed reactivity with reconstituted HDL (rHDL), but T123I retained activity with low density lipoprotein. To determine whether defective binding to rHDL was responsible for the low activity of both mutants with rHDL, the equilibrium binding constants were measured directly with isothermal titration calorimetry and surface plasmon resonance (SPR) methods. The results indicated that the affinities of the mutants for rHDL were only about 2-fold lower than the affinity of wild type LCAT (Kd = 2.3 x 10(-7) M). Together, the activity and equilibrium binding results suggest that the T123I mutant is defective in activation by apolipoprotein A-I, and the N228K mutant has impaired binding of lipid substrate to the active site. In addition, the kinetic binding rate constants determined by the SPR method indicate that normal LCAT dissociates from rHDL, on average, after one catalytic cycle.

Animals↗
PubMed1998

Genetic relationship of populations in China.

Despite the fact that the continuity of morphology of fossil specimens of modern humans found in China has repeatedly challenged the Out-of-Africa hypothesis, Chinese populations are underrepresented in genetic studies. Genetic profiles of 28 populations sampled in China supported the distinction between southern and northern populations, while the latter are biphyletic. Linguistic boundaries are often transgressed across language families studied, reflecting substantial gene flow between populations. Nevertheless, genetic evidence does not support an independent origin of Homo sapiens in China. The phylogeny also suggested that it is more likely that ancestors of the populations currently residing in East Asia entered from Southeast Asia.

Animals↗
PubMed1998

Targeted expansion of genetically modified bone marrow cells.

The ability to specifically target a mitogenic signal to a population of genetically modified primary cells would have potential applications both for gene and cell therapy. Toward this end, a gene encoding a fusion protein containing the FK506-binding protein FKBP12, fused to the intracellular portion of the receptor for thrombopoietin (mpl), was introduced into primary murine bone marrow cells. Dimerization of this fusion protein through the addition of a dimeric form of the drug FK506, called FK1012, resulted in a marked proliferative expansion of marrow cells that was restricted to the genetically modified population. FK1012's proliferative effect was sustained and reversible. An apparent preference for differentiation along the megakaryocytic lineage was observed. This approach allows for the specific delivery of a mitogenic signal to a population of genetically modified primary cells and may have applications for studies in hematopoiesis and receptor biology, and for gene and cell therapy.

Animals↗
PubMed1998

[Fluorescence-based semi-automated gene scan with microsatellite markers by multiplex PCR techniques].

OBJECTIVE: To develop a high output and low cost multiplex PCR approach to facilitating large scale gene scan and gene typing with microsatellite markers. METHODS: 5-15 pairs of primers of microsatellite loci were added in one single tube with 5ul reaction volume, containing 10 mmol/L Tris-HCl (pH8.3), 50 mmol/L KCl,0. 1mg/ml gelatin, 3.0 mmol/L MgCl2, 200micromol/L dNTPs (each), 0.25U Taq DNA polymerase, Taq Start antibody and DNA templates. PCR thermocycles were carried out on Perkin Elmer Gene Amp PCR System 9600 with touch-down algorithm (the annealing temperature was decreased by 0.5 C in each cycle) to meet the different demands of different primers. RESULTS: Up to 10-15 loci were labeled by different fluorescents or by the same fluorescent, but their PCR amplification fragments did not overlap in size. Almost all target microsatellite loci were successfully co-amplified in a 5 microliter reaction volume,electrophoresized and analyzed in a single gel lane with Perkin Elmer ABI 373A DNA sequencer, and 9 microsatellite loci were well genotyped. CONCLUSION: This high output and low cost genotyping protocol is applicable to gene mapping, human evolution and forensic analysis.

Genotype↗
PubMed1998

Stimulating cell proliferation through the pharmacologic activation of c-kit.

Previous studies have shown that expression of a membrane targeted chimeric protein containing the erythropoietin receptor (EpoR) cytoplasmic domain fused to the FK506-binding peptide FKBP12 allowed Ba/F3 cells to be rescued from interleukin-3 (IL-3) deprivation using a dimeric form of FK506, called FK1012. In this report, a similar approach is applied to the c-kit receptor. Expression of a membrane targeted fusion protein containing the c-kit receptor linked to one or more copies of FKBP12 allowed Ba/F3 cells to be switched from IL-3 dependence to FK1012-dependence. Similar results were obtained using an alternative dimerizer of FKBP12 domains called AP1510. Pharmacologic dimerization of chimeric proteins containing only a single FKBP12 domain confirmed that receptor dimerization is sufficient for proliferative signaling. Interestingly, while the proliferative effects of both FK1012 and AP1510 were reversible, FK1012-driven proliferation persisted for several days after drug withdrawal. Furthermore, much higher concentrations of FK506 were required to inhibit FK1012-mediated proliferation than were required to inhibit AP1510-mediated proliferation. The persistence of FK1012's effect appeared to be specific to clones expressing c-kit-containing fusion proteins. These results suggest that pharmacologically-responsive fusion proteins containing c-kit may be useful for specifically and reversibly expanding genetically modified hematopoietic cell populations.

Animals↗
PubMed1998

Scatter factor promotes motility of human glioma and neuromicrovascular endothelial cells.

Malignant gliomas are characterized by rapid growth, infiltration of normal brain tissue, and high levels of tumor-associated angiogenesis. The genetic and local environmental tissue factors responsible for the malignant progression from low to high grade gliomas and the highly malignant behavior of glioblastomas are not well understood. In a study of 77 human brain tissue extracts, high grade (III-IV) tumors had significantly greater scatter factor (SF) content than did low grade tumors or non-neoplastic tissue. To investigate the potential significance of SF accumulation in gliomas, we measured the effects of SF on DNA synthesis and motility of cultured human glioma cell lines. SF stimulated DNA synthesis in 7/10 glioma cell lines and in 3/3 neuromicrovascular endothelial cell (NMVEC) lines, consistent with our previous report that SF stimulated cell proliferation of a few human glioma cell lines. SF markedly stimulated the chemotactic migration of 10/10 glioma cell lines as well as 3/3 NMVEC lines. In addition, SF stimulated the 2-dimensional migration of glioma cells on culture surfaces coated with specific extracellular matrix molecules (collagen i.v., laminin, and fibronection). As expected based on these biologic responses to SF, 10/10 glioma lines and 4/4 NMVEC lines expressed mRNA for c-met, the SF receptor. To assess the possible in vivo significance of these migration assays, we compared the chemotactic response of a glioma cell line to human brain cyst fluids and tumor extracts that contained high or low SF concentrations. Fluids and extracts with high SF content tended to induce higher levels of chemotactic migration than did fluids and extracts with low SF content. Addition of anti-SF monoclonal antibody (MAb) inhibited migration induced by fluids and extracts with high SF content by about 30-50%.

Brain Neoplasms↗
PubMed1998

Crystallization and preliminary crystallographic investigation of porcine quinolinate phosphoribosyltransferase.

Quinolinate phosphoribosyltransferase (QPRT), purified from hog liver, has been crystallized using PEG 8000 as the precipitant. The crystals form long hexagonal rods in the space group P6322 with cell dimensions a = b = 121.7, c = 94.5 A. Based on the unit-cell dimensions and the calculated molecular mass of 33 500 Da, the Matthews coefficient suggests one molecule per asymmetric unit (Vm = 3.45 A3 Da-1; 64% solvent). Three native data sets were collected to a resolution of 2.5 A and merged to provide a set that is 94.7% complete, with an Rsym value of 9.6%.

Animals↗
PubMed1998

Transplacental transmission of human polyomavirus BK.

The presence of BK virus (BKV) and JC virus (JCV) in autopsy materials (placenta, brain, and kidney) of aborted fetuses was investigated by PCR using two sets of primers, specific for the regulatory region (RR) and for the capsid protein VP1, respectively. The RR of BKV was detected in 12 samples of placenta and brain and in nine samples of kidney obtained from 15 fetuses. Out of the 12 positive cases, four placentas, one brain, and three kidney samples also showed the presence of BKV DNA in the VP1 region. Of 12 placentas from a control group with a normal pregnancy outcome, the RR of BKV was detected in six samples, four of which were also positive for the VP1 region. None of the samples from either group was positive for the RR of JCV. In two cases, the nucleotide sequence of the BK RR demonstrated that the viruses isolated from maternal and fetal tissues showed a high homology with one another and had a characteristic deletion of the R63 box compared to the archetype strain. The results indicate that BKV may be transmitted vertically.

Abortion, Induced↗
PubMed1998

Human and murine antibody recognition is focused on the ATPase/helicase, but not the protease domain of the hepatitis C virus nonstructural 3 protein.

The hepatitis C virus (HCV) nonstructural (NS) 3 protein has been shown to possess at least two enzymatic domains. The amino terminal third contains a serine-protease domain, whereas the carboxy terminal two thirds is comprised of an adenosine triphosphatase (ATPase)/helicase domain. These domains are essential for the maturation of the carboxy-terminal portion of the HCV polyprotein and catalyze the cap synthesis of the RNA genome. In this report, human and murine antibody responses induced by NS3 were characterized using a recombinant full-length NS3 (NS3-FL) protein, or the isolated protease or ATPase/ helicase domains, expressed and purified from Escherichia coli. Sera from 40 patients with chronic HCV infection were assayed in enzyme-linked immunoassays (EIAs) for antibody binding to the panel of NS3 proteins. Virtually all patient sera contained antibodies specific for NS3-FL and the ATPase/helicase domain, whereas only 10% of sera reacted with the protease domain of NS3. Human antibodies reactive with NS3-FL were highly restricted to the immunoglobulin G1 (IgG1) isotype and were inhibited by soluble ATPase/helicase, but not by the protease domain. The anti-NS3 (ATPase/helicase) reactivity decreased on denaturation by sodium dodecyl sulfate (SDS) and beta-mercaptoethanol (2ME), suggesting the recognition of nonlinear or conformational B-cell determinants. Similar to infected humans, mice immunized with NS3-FL developed high-titered primary antibody responses to the NS3 ATPase/ helicase domain, whereas an anti-NS3 protease response was not observed after primary or secondary immunizations. Thus, the human and murine humoral immune responses to the HCV NS3 protein are focused on the ATPase/helicase domain, are restricted to the IgG1 isotype in humans, and are conformationally dependent. Unexpectedly, in both species, the NS3 protease domain, present in the context of the full-length NS3, appears to possess low intrinsic immunogenicity in terms of antibody production.

Adenosine Triphosphatases↗