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Biomedical subjects

M Lu

Publications and source records attributed to M Lu.

At least 163 records · Page 9Linked to original sources
PubMed1999

Induction of gastritis and gastric ulcer in Mongolian gerbils infected with Helicobacter pylori.

OBJECTIVE: To induce the model of Mongolian gerbil infected by Helicobacter pylori (HP) and to observe the changes of the infiltration and the proliferation of inflammatory cells before and after the bactericidal treatment. METHODS: The animal model of HP infection was induced by inoculating the HP strain (American Type Culture Collection) to male Mongolian gerbil MGS/Sea (SPF). Half a month, 1 month and 3 months after inoculation, kill the animals and make HE staining and immunohistochemistry staining of the stomach to observe the pathological changes. RESULTS: The infiltration of a great number of inflammatory cells was observed with the center of the mucosa of pylorus at the second week of HP infection. At the 3rd month of infection, ulcer appeared near the lesser curvature side of the pylorus. On the early stage of infection, the lesion was acute inflammation characterized by the neutrophilic infiltration, and then transformed into the chronic inflammation characterized by the lymphatic infiltration and the wide formation of lymphatic follicles. CONCLUSION: Mongolian gerbil is an ideal and standard animal model of HP infection.

Animals↗
PubMed1999

[Colorectal cancer: lymphatic metastasis and choice of operation].

OBJECTIVE: To study lymphatic metastasis of colorectal cancer for deceding the of dissection extent of dissection. METHODS: Six hundred and twenty-three lymph nodes from 74 cases of colorectal cancer were analyzed after D(3) resection. They were classified into peritumor, longitudinal spread, and upward spread groups. The metastasis rate of lymph node and its incidence were calculated. RESULTS: The metastasis rate of lymph node and its incidence in the peritumor, longitudinal spread, and upward spread (N(2) and N(3)) groups were 47.2% and 38.6%, 22.8% and 18.6%, and 29.7% (20.3% and 9.4%) and 10.2% (19.0% and 5.3%), respectively. The distribution rate of metastatic lymph node was 61.2%, 17.1%, and 21.6% in the peritumor, longitudinal spread, and upward spread groups, respectively. Within 2.0 cm on the anal side of rectal cancer, the metastasis rate was 3.7%, whereas in 2.0 - 4.0 cm no metastasis was observed cancer at the lower part of the rectum demonstrated a higher lateral metastasis rate. CONCLUSIONS: Colorectal cancer tends to metastasize to longitudinal and the risk of metastasis increased in the stage of pT(3) and pT(4) or low differentiation stage. Jump metastasis is also a feature. D(3) radical resection is necessary for colorectal cancer, but extended lateral lymph node needs enectomy or total mesorectal excision. No residual tumor tissue exists at the anastomosis site after low anterior resection when the excision distance is beyond 2.0 cm from the anal margin of rectal cancer.

Adult↗
PubMed1999

[Hepatic arterial infusion of 32P-radionuclide microspheres for radiation therapy of hepatocellular carcinoma].

OBJECTIVE: To investigate the efficacy of internal radiation of (32)P-glass microspheres ((32)P-GMS) in unresected hepatocellular carcinoma (HCC) via subcutaneous arterial port. METHODS: Hepatic arterial (99)technetium-macroaggregate albumin ((99)Tc-MAA) scanning via subcutaneous arterial port was undertaken to measure lung/liver shunting ratio and tumor/liver ratio. Hepatic arterial infusion of (32)P-GMS was performed in 17 cases of HCC with a dose from 1.11 to 1.30 GBq. Twenty cases of HCC undergoing hepatic arterial chemoembolization (HACE) in the same period served as controls group. RESULTS: There was no treatment-related death in the 17 cases. In 7 of the 17 cases, AFP level and/or tumor size decreased by 50% after treatment, with a response rate of 64.7%. The median survival time was 5.5 months, and the 3-, 6-, 9-, 12-month survival rates were 94.1%, 44.1%, 31.0%, 24.4%, respectively. The therapeutic efficacy was better than that of HACE. The survival time was significantly longer in patients with T/N ratio >or= 2 than in those with T/N < 2 (P < 0.05). CONCLUSIONS: Hepatic arterial infusion of (32)P-GMS is an alternative treatment for unresected HCC.

Adult↗
PubMed1999

[In vitro adherence of bacteria to intraocular lenses of different materials].

OBJECTIVE: To compare the in vitro adherence of different bacteria onto the surface of various intraocular lenses (IOLs). METHOD: Electron microscopic and bacterial culture quantitative methods were used to study the adherence of Staphylococcus (S) epidermidis, Staphylococcus aureus and Pseudomonas (P) aeruginosa onto the surface of PMMA and other three foldable IOL materials (HEMA, ACRY, SI). RESULTS: S. Epidermidis: HEMA < ACRY < SI < PMMA; S. aureus: HEMA was the least and PMMA was the most, no significant difference between ACRY and SI IOLs; P. aeruginosa: HEMA was the least while no significant difference among PMMA, SI and ACRY IOLs (P > 0.05). CONCLUSION: The foldable IOLs have the potent ability to reduce the infectious endophthalmitis after surgery of extraction of cataract with IOL implantation.

Acrylic Resins↗
PubMed1999

[Platelet stereological study in patients with HFRS].

To investigate the effects of stereological alteration of platelets on hemorrhage in hemorrhagic fever with renal syndrome(HFRS), platelet mean cross area(A), area density of alpha-granules(Na), volume density(Vv), the mean open tubule(OCS) and pseudopodia mean(M) were performed stereometric analysis in 12 patients with HFRS. The platelet A was observed, and no significant difference was found compared with the control(P > 0.05), while the number of pseudopodia M was higher, and the open tubule number was lower than those of the control(p < 0.01). The results suggest that in addition to the total platelet count decrement, the quality deterioration and functional activity abnormalities of platelets play an important role on the disordered hemostasis and coagulation in HFRS.

Adult↗
PubMed1999

[PCR for the detection of 16S rRNA gene bacteria].

According to the high conservative region of 16S rRNA gene in bacteria, PCR primers of the broad-range bacteria, gram-positive bacteria and gram-negative bacteria were synthesized to detect 13 bacterium species and (40) clinical specimens. All the tested bacterium species were positive. The lowest concentration of Escherichia Coli detected by serial dilution was 4 CFU.ml-1. The positive rate of PCR (27/40) was higher than that of bacterium culture(18/40). The results indicate that these PCR primers possess high specificity and sensitivity in identifying 16S rRNA gene of bacteria.

Bacteriuria↗
PubMed1999

[Determination of total scopoletin in Caulis Erycibes by RP-HPLC].

OBJECTIVE: To accumulate data for quality control of Caulis Erycibes. METHOD: The total-scopoletin in Caulis Erycibes was determined by RP-HPLC, using CLC-ODS1 column, 0.5% glacial acetic acid in methanol-water(26:55) as mobile phase and UV detector at 310 nm. RESULT: The average recovery is 99.37% and RSD 0.39%. CONCLUSION: Determination data have been obtained for fourteen batches of three species, and the contents of scopoletin should be no less than 30 mg/100 g.

Chromatography, High Pressure Liquid↗
PubMed1999

[The applied anatomy and measure of nasolacrimal duct].

OBJECTIVE: To know the anatomy of nasolacrimal duct. METHOD: 80 half-skulls of chinese adult were used to observe shapes of the orifice. RESULT: Five shapes of the orifice were found. Slit-shape was the most in all shapes. 73 nasolacrimal ducts and situation of orifices have been measured with results as follows: (1) The nasolacrimal duct length is 14.14 mm (mean value); (2) The distance from the inferior margin of the anterior nostril to the anterior margin of the orifice (D.N.O.) is 29.00 mm (mean value); (3) The distance from the anterior attachment of the inferior turbinate to the anterior margin of the orifice is 11.70 mm (mean value); (4) The distance from the inferior margin of the anterior nostril to the anterior attachment of the inferior turbinate (D.N.T) is 18.30 mm (mean value). With analysis of linear regression, the relationship between the "D.N.T." and the nasolacrimal duct length, the "D.N.T." and the "D.N.O." is positive linear correlation respectively, "D.N.T." has been able to be measured easily, so the nasolacrimal duct length and the situation of the orifice have been recognized. CONCLUSION: D.N.T. may be used in clinical teaching and researching work.

Adult↗
PubMed1998

High-level expression of secreted glycoproteins in transformed lepidopteran insect cells using a novel expression vector.

An expression cassette for continuous high-level expression of secreted glycoproteins by transformed lepidopteran insect cells has been developed as an alternative to baculovirus and mammalian cell expression systems. The expression cassette utilizes the promoter of the silkmoth cytoplasmic actin gene to drive expression from foreign gene sequences, and also contains the ie-1 transactivator gene and the HR3 enhancer region of BmNPV to stimulate gene expression. Using an antibiotic-resistance selection scheme, we have cloned a Bm5 (silkmoth) cell line overexpressing the secreted glycoprotein juvenile hormone esterase (JHE-KK) at levels of 190 mg/L in batch suspension cultures. A baculovirus (AcNPV) expressing the same gene under the control of the p10 promoter of AcNPV produced only 4 mg/L active JHE in static cultures of infected Sf21 cells. A cloned Bm5 cell line overexpressing a soluble isoform of the alpha-subunit of the granulocyte-macrophage colony stimulating factor receptor (solGMRalpha) was also generated and produced five times more solGMRalpha in static cultures than a cloned BHK cell line obtained by transformation with a recombinant expression cassette utilizing the human cytomegalovirus (CMV) enhancer-promoter system. Finally, we show that recombinant protein expression levels in transformed Bm5 cells remain high in serum-free media, that expression is stable even in the absence of antibiotic selection, and that lepidopteran cells other than Bm5 may be used equally efficiently with this new expression cassette for producing recombinant proteins.

Animals↗
PubMed1998

Tetracycline repressor, tetR, rather than the tetR-mammalian cell transcription factor fusion derivatives, regulates inducible gene expression in mammalian cells.

This article describes the first (to our knowledge) tetracycline-inducible regulatory system that demonstrates that the tetracycline repressor (tetR) alone, rather than tetR-mammalian cell transcription factor fusion derivatives, can function as a potent trans-modulator to regulate gene expression in mammalian cells. With proper positioning of tetracycline operators downstream of the TATA element and of human epidermal growth factor (hEGF) as a reporter, we show that gene expression from the tetracycline operator-bearing hCMV major immediate-early enhancer-promoter (pcmvtetO) can be regulated by tetR over three orders of magnitude in response to tetracycline when (1) the reporter was cotransfected with tetR-expressing plasmid in transient expression assays, and (2) the reporter unit was stably integrated into the chromosome of a tetR-expressing cell line. This level of tetR-mediated inducible gene regulation is significantly higher than that of other repression-based mammalian cell transcription switch systems. In an in vivo porcine wound model, close to 60-fold tetR-mediated regulatory effects were detected and it was reversed when tetracycline was administered. Collectively, this study provides a direct implementation of this tetracycline-inducible regulatory switch for controlling gene expression in vitro, in vivo, and in gene therapy.

Animals↗
PubMed1998

The A kinase anchoring protein is required for mediating the effect of protein kinase A on ROMK1 channels.

In the present study, we have used the two-electrode voltage-clamp and patch-clamp techniques to study the effects of forskolin and cAMP on the ROMK1 channels, which are believed to be the native K+ secretory channels in the kidney. Addition of 1 microM forskolin or 100 microM 8-bromo-cAMP, within 10 min, has no significant effect on the current of ROMK1 channels expressed in Xenopus oocytes. In contrast, application of 1 microM forskolin, within 3 min, significantly increased whole-cell K+ current by 35%, when ROMK1 channels were coexpressed with the A kinase anchoring protein AKAP79, which was cloned from neuronal tissue. Two lines of evidence indicate that the effect of forskolin is mediated by a cAMP-dependent pathway: (i) Addition of 100 microM 8-bromo-cAMP mimics the effect of forskolin and (ii) the effect of forskolin and cAMP is not additive. That AKAP is required for the effect of cAMP is further supported by experiments in which addition of ATP (100 microM) and cAMP (100 microM) restored the activity of run-down ROMK1 channels in inside-out patches in oocytes that coexpressed ROMK1 and AKAP79 but not in those that expressed ROMK1 alone. Moreover, when we used RII, the regulatory subunit of type II protein kinase A, in an overlay assay, we identified a RII-binding protein in membranes obtained from the kidney cortex but not in membranes from oocytes. This suggests that the insensitivity of ROMK1 channels to forskolin and cAMP is due to the absence of AKAPs. We conclude that AKAP may be a critical component that mediates the effect of protein kinase A on the ROMK channels in the kidney.

Adenosine Triphosphate↗
PubMed1998

Advanced glycation end products increase retinal vascular endothelial growth factor expression.

Advanced glycation end products (AGEs) are linked with the development of diabetic retinopathy; however, the pathogenic mechanisms are poorly defined. Vascular endothelial growth factor (VEGF) levels are increased in ischemic and nonischemic diabetic retina, and VEGF is required for the development of retinal and iris neovascularization. Moreover, VEGF alone can induce much of the concomitant pathology of diabetic retinopathy. In this study, we found that AGEs increased VEGF mRNA levels in the ganglion, inner nuclear, and retinal pigment epithelial (RPE) cell layers of the rat retina. In vitro, AGEs increased VEGF mRNA and secreted protein in human RPE and bovine vascular smooth muscle cells. The AGE-induced increases in VEGF expression were dose- and time-dependent, inhibited by antioxidants, and additive with hypoxia. Use of an anti-VEGF antibody blocked the capillary endothelial cell proliferation induced by the conditioned media of AGE-treated cells. AGEs may participate in the pathogenesis of diabetic retinopathy through their ability to increase retinal VEGF gene expression.

Animals↗
PubMed1998

Surface salt bridges stabilize the GCN4 leucine zipper.

We present a study of the role of salt bridges in stabilizing a simplified tertiary structural motif, the coiled-coil. Changes in GCN4 sequence have been engineered that introduce trial patterns of single and multiple salt bridges at solvent exposed sites. At the same sites, a set of alanine mutants was generated to provide a reference for thermodynamic analysis of the salt bridges. Introduction of three alanines stabilizes the dimer by 1.1 kcal/mol relative to the wild-type. An arrangement corresponding to a complex type of salt bridge involving three groups stabilizes the dimer by 1.7 kcal/ mol, an apparent elevation of the melting temperature relative to wild type of about 22 degrees C. While identifying local from nonlocal contributions to protein stability is difficult, stabilizing interactions can be identified by use of cycles. Introduction of alanines for side chains of lower helix propensity and complex salt bridges both stabilize the coiled-coil, so that combining the two should yield melting temperatures substantially higher than the starting species, approaching those of thermophilic sequences.

Alanine↗
PubMed1998

A rapid method for determining standard 10/10 electrode positions for high resolution EEG studies.

This report describes the basic principle and examines the comparative accuracy of a novel method for locating 3-D coordinates of electrode positions on the head. The method involves calculation of the 3-D coordinates for any array of 10/10 electrode positions from 14 straight-line distances between 11 10/10 electrodes. In 11 subjects the 3-D coordinates of 64 scalp electrodes embedded in an electrode cap were identified with the novel method, and also with a standard commercial magnetic field digitizer. The outcomes from the two methods were compared with directly measured coordinates of all 64 positions (cf. De Munck, J.C., Vijn, P.C.M. and Spekreijse, H. A practical method for determining electrode positions on the head. Electroenceph. clin. Neurophysiol., 1991, 89: 85-87). Coordinates in 3 dimensions obtained using the new method were significantly closer to the directly measured values than those from the magnetic field digitizer. The new method was also quicker and requires less specialized instrumentation than the magnetic field digitization method. The novel method appears to be a valid and convenient tool for use with EEG analysis techniques that require specific information about 10/10 electrode positions.

Adolescent↗
PubMed1998

The "interferon sensitivity determining region" of hepatitis C virus is a stable sequence element.

BACKGROUND/AIMS: A sequence of 40 amino acids within the nonstructural protein 5A of hepatitis C virus (HCV) has been suggested to be an interferon sensitivity determining region (ISDR). The variations in the ISDR after 12-14 years of chronic infection and the correlation between ISDR and interferon response were studied in patients who were infected by the same HCV isolate. METHODS: We determined the HCV-ISDRs of 13 chronically infected patients by direct sequencing of polymerase chain reaction products. All patients were infected by isolate HCV-AD78, but differed with respect to their sensitivity to interferon. Four patients were complete responders, two patients were non-responders, and seven showed a partial response. RESULTS: The ISDR of HCV-AD78 differed from a prototypical HCV-1b sequence in one amino acid and was therefore classified as an intermediate type. Direct sequencing of the HCV-ISDRs of the patients 12-14 years after infection, but before interferon therapy, revealed a rate of 2.2x10(-3) nucleotide substitutions per site per year, resulting in only single intermediate type amino acid exchanges. All sequences ranked with the intermediate type. Moreover, during interferon treatment no selection to a wild type ISDR was observed in five partial responders. CONCLUSIONS: Within the homogeneous patient group examined here, no correlation was found between the ISDR and the interferon response. Recent studies found only a small number of mutant type ISDRs in Europe. Additionally, our results indicate that the ISDR is a stable sequence element. This provides an explanation for the divergent data relating to the importance of the ISDR in different geographical regions.

Amino Acid Sequence↗
PubMed1998

Clinical performance of the AMDL DR-70 immunoassay kit for cancer detection.

A clinical study using DR-70 immunoassay for the detection of 13 different cancers have been conducted with 277 healthy subjects and 136 cancer patients. The test results showed that the DR-70 immunoassay kit was capable of detecting cancers with high degree of specificity and sensitivity. At 95% specificity level, the sensitivity of the assay was 87.8%, 92.6%, 65.2% and 66.7%, respectively for lung, stomach, breast and rectum cancers. Furthermore the test kits were shown to be stable and performed reproducibly.

Adolescent↗
PubMed1998

A conformation-specific monoclonal antibody reacting with fusion-active gp41 from the human immunodeficiency virus type 1 envelope glycoprotein.

The gp41 subunit of the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein plays a major role in the membrane fusion step of viral infection. The ectodomain of gp41 contains a six-helix structural domain that likely represents the core of the fusion-active conformation of the molecule. A monoclonal antibody (MAb), designated NC-1, was generated and cloned from a mouse immunized with the model polypeptide N36(L6)C34, which folds into a stable six-helix bundle. NC-1 binds specifically to both the alpha-helical core domain and the oligomeric forms of gp41. This conformation-dependent reactivity is dramatically reduced by point mutations within the N-terminal coiled-coil region of gp41 which impede formation of the gp41 core. NC-1 binds to the surfaces of HIV-1-infected cells only in the presence of soluble CD4. These results indicate that NC-1 is capable of reacting with fusion-active gp41 in a conformation-specific manner and can be used as a valuable biological reagent for studying the receptor-induced conformational changes in gp41 required for membrane fusion and HIV-1 infection.

Amino Acid Sequence↗