Biomedical subjects

X He

Publications and source records attributed to X He.

At least 307 records · Page 17Linked to original sources

PubMed1997

Stimulation with cholecystokinin leads to increased ratio between mRNA levels for anionic and cationic trypsinogen in rat pancreas.

An increased ratio between serum levels of immunoreactive anionic and cationic trypsin is a common finding in many forms of pancreatic disease. Experimental studies have shown that increased stimulation with cholecystokinin (CCK) leads to an increase in the ratio between the pancreatic content of anionic and cationic trypsin. To study whether this effect is caused by increased pancreatic synthesis of anionic trypsin in relation to cationic trypsin we studied the levels of mRNA for anionic and cationic trypsinogen in pancreatic extracts from rats exposed to increased CCK levels through chronic subcutaneous administration of CCK. Northern blot and slot blot hybridization techniques were used. The ratio between mRNAs for anionic and cationic trypsin was significantly higher in CCK-treated rats: median level, 2.04 (range, 1.33-4.08) versus a median level of 1.15 (range, 0.97-2.17) in the control group: P < 0.01. These findings support the view that chronic CCK stimulation leads to the increased synthesis of anionic trypsinogen compared to cationic trypsinogen.

Animals↗

PubMed1997

Polarized distribution of key membrane transport proteins in the rat submandibular gland.

Immunofluorescence labelling and confocal microscopy were employed to examine the polarized distribution of several membrane transport proteins believed to be essential for salivary secretion in the rat submandibular gland. The Na+/K+-ATPase, Na+/H+ exchanger isoform 1 (NHE1), and the secretory Na+/K+/2Cl- cotransporter isoform were all found in the basolateral membranes of acinar and intralobular duct cells. Anion exchanger isoform 2 (AE2) was found only in the basolateral membranes of acinar cells, while AE1 was absent from glandular epithelial cells. Aquaporin 5 was detected in the apical membranes of acinar cells, while the cystic fibrosis transmembrane conductance regulator was found only in apical membranes of intralobular duct cells. NHEs 2 and 3 were found in the apical membranes of both acinar and intralobular duct cells. Our results are generally consistent with the expected distribution of most transporters based on previous physiological and pharmacological experiments. However, the apical localization of NHEs 2 and 3, and the presence of the secretory isoform of the Na+/K+/2Cl- cotransporter in intralobular duct cells were not predicted.

Animals↗

PubMed1997

Immunoreactivity of human MAb BT32/A6 with neuroepithelial tumors.

The present study was undertaken to determine the pattern of immunoreactivity of BT32/A6, a human IgM monoclonal antibody (MAb), with the following histological panels: 1) 30 human and non-human cell lines, 2) 32 normal human tissues, and 3) 28 tumors of central neuroepithelial origin (16 astrocytic; 11 non-astrocytic). Antibody BT32/A6 recognizes a surface and cytoplasmic antigen present on a variety of human tumor cell lines including gliomas, melanomas, neuroblastomas, and a few sarcomas. The antigen is present (at least focally) on 15/16 astrocytic tumor tissue sections (94%), and in some cases, on close to 100% of cells. All malignant cell types, including small anaplastic cells, giant cells, gemistocytic cells, and cells forming pseudopalisades were labeled by MAb BT32/A6. Non-astrocytic neuroepithelial tumors did not stain appreciably with MAb BT32/A6. There was weak immunoreactivity in a small subset of normal human tissues of epithelial and lymphoid origin, with the exception of adrenal cortex, which exhibited weak to moderate staining. All normal tissues of neuroectodermal and mesenchymal origin were unreactive. In conclusion, MAb BT32/A6 appears to be unique in that it recognizes a highly-expressed astrocytic tumor-associated antigen that is present on both low and high grade tumors. This makes it a strong candidate for further studies aimed at establishing its usefulness in the treatment of human astrocytic tumors.

Antibodies, Monoclonal↗

PubMed1997

Monocyte-dependent regulation of T lymphocyte activation through CD98.

CD98 is a 125 kDa heterodimer, which is strongly expressed on the surface of activated and proliferating cells. Its expression is strikingly regulated during T cell differentiation and activation, but the role of CD98 during T lymphocyte responses is not yet understood. We report here that proliferation of resting peripheral blood mononuclear cells (PBMC) induced by lectin, superantigen (SAg) or conventional antigens was blocked by anti-CD98 heavy chain (CD98hc) mAb. In contrast, anti-CD98hc did not block responses of T cell clones or lines. Anti-CD98hc inhibited IL-2 receptor expression and progression of T cells from G1 to S phase, but did not reduce expression of the IL-2 gene. Anti-CD98hc mAb did not regulate the initial activation events involving the TCR and co-receptor structures, but instead inhibited T lymphocyte responses even when added 18 h or more after the activation stimulus. Further experiments demonstrated that anti-CD98 was not directly affecting T cells in this system, but was instead acting on accessory cells. This was supported using a novel xenogeneic system that takes advantage of the lack of xenoreactivity of purified human T cells against mouse splenocytes. Despite absence of a direct xenoresponse to murine spleen cells, human T cells were activated by SAg presented by murine splenic antigen-presenting cells (APC). Murine anti-human CD98hc did not block T cell proliferation in this system. Furthermore, responses using monocyte-depleted PBMC as APC were not blocked by anti-CD98hc. Taken together, the present data suggests that triggering of human monocyte CD98 can suppress T cell proliferation by a process that halts progression through the cell cycle of recently activated T lymphocytes. This may represent a novel pathway for monocyte regulation of T cell activation.

Antibodies, Blocking↗

PubMed1997

[Blocking effects of dimethoate on acetylcholine receptor channels].

The patch-clamp technique was used to study the inhibitory effect of dimethoate, an organophosphrous pesticide, on the membrane of embryoinc Xenopus musle cells in culture. Using whole-cell clamp and cell-attached clamp, we found that the direct inhibitory effects of dimethoate was evidenced on both miniature end-plate currents (MEPC) and single channel currents. Dimethoate increased the amplitude and frequency of MEPC at a lower concentration (21.6 mumol/L) while both decreased at a higher concentration (237 mumol/L). The dimethoate at a concentration of 146 mumol/L shortened the opening time and decreased the opening probability of the single channel. The results show that dimethoate is an AChR channel blocker.

Animals↗

PubMed1997

[The expression of EGF mRNA and EGF receptors in human trabecular meshwork cells in vitro].

OBJECTIVE: To demonstrate that cultured trabecular meshwork cells can secrete epidermal growth factor (EGF) and there are EGF receptors (EGFRs) on the cells. METHODS: Human trabecular meshwork cells were cultured in vitro and passaged 3-5 times. Immunohistochemical stain was used to detect EGFRs on the trabecular meshwork cell membrane. EGF cDNA probe, alpha-32P isotope labeling and dot blot hybridization autoradiographic method were used to detect EGF mRNA in the cells. RESULTS: Cultured human trabecular meshwork cells were obtained. EGFR immunostain was positive, and the reaction of brown color was at the surface of the cells. Dot blot hybridization autoradiography showed that trabecular cells can express EGF mRNA. CONCLUSIONS: Trabecular meshwork cells can secrete EGF. There are EGFRs on the membrane of trabecular meshwork cells. It is suggested that probably up-regulating the receptors or promoting the cells to secrete growth factors have potential significance in the regeneration of trabecular cells and recovery of the cell functions in open angle glaucoma.

Adolescent↗

PubMed1997

[Content determination of baicalin and baicalein in shuanghuanglian powdery injection by the method of HPLC-ECD].

The contents of baicalin and baicalein in Shuanghuanglian Powdery Injection have been determined by the method of HPLC-ECD under following conditions: column-ERC-ODS-1161, 6 mm x 100 mm; temperature-55 degrees C; mobile phase-0.1 mol/L KH2PO4, acetic acid and tetrahydrofuran (1000:100:190); flow rate-0.8 ml/min; detector voltage-+650 mV. The result shows the limit of detection for baicalin and baicalein to be 25 ng and 50 ng respectively, with an average recovery of 100.1% and 99.7% respectively. Highly reproducible, rapid, simple, convenient and accurate, this method is good for the content determination of baicalin and baicalein in Chinese medicinal herbs and preparations.

Chromatography, High Pressure Liquid↗

PubMed1997

[Preparation and characterization of a McAb against tissue factor pathway inhibitor].

OBJECTIVE: To prepare monoclonal antibody (McAb) against tissue factor pathway inhibitor (TFPI). METHODS: Twice intrasplenic immunization of BALB/c mice with TFPI-binded nitrocellulose paper followed by an intraperitoneal boost with TFPI raised two hybridoma cell lines, 4F8 and 4F4, by hybridoma technique, 4F8 was studied in detail. The mode value of its chromosome is 93. The Ig class of McAb 4F8 was IgG1. The McAb was purified from ascites by a simple procedure of caprylic acid pre cipitation. The purified McAb was conjugated with horseradish peroxidase (HRP) by a modified periodate oxidation procedure. RESULTS: Immunoblotting indicated that the McAb recognized a single band of TFPI with a molecular weight of 34800. The McAb was also proved to shorten markedly the dilute thromboplastin coagulation time of factor IX-deficient and normal plasma. The results of Sandwich ELISA using the HRP labeled McAb showed that the mean TFPI in normal human plasma is 103.2 +/- 11.5 microg/L, being similar to that measured with TFPI ELISA kit from America Diagnostica Inc. (98.4 +/- 10.3 microg/L) (r=0.92). CONCLUSION: McAb 4F8 may be a useful reagent for TFPI research.

Animals↗

PubMed1997

[In vitro study on the effects of the novel retinoids on the proliferation and differentiation of normal and leukemic cells].

OBJECTIVE: To evaluate the prospect for clinical use of four novel retinoid compounds (retinoid 1, retinoid 2, retinoid 3 and retinoid 4), which were different structurally from all-trans retinoic acid. METHODS: The effects of the four retinoids on the differentiation and clonal proliferation of NB4 cells and fresh acute promyelocytic leukemia (APL) cells and on the proliferation of normal hematopoietic cells were studied. Cell morphological examination,nitro tetrazolium blue reduction test, cell cycle dynamics, and colony formation assay were used in the study. RESULTS: Novel retinoids induced differentiation of NB4 and fresh APL cells, and markedly inhibited CFU-L growth of NB4 and fresh APL cells. The activity related to their chemical structures and retinoid 2 was more active. The novel retinoids enhanced the growth of CFU-GM, CFU-E and CFU--Meg of normal bone marrow cells. CONCLUSION: These novel retinoids, especially retinoid 2, may regulate the proliferation and differentiation of normal hematopoiesis, induce APL cell differentiation and maturation, and are worthy of further study for clinical use.

Cell Differentiation↗

PubMed1997

[Scale-up preparation of hydrophobic interaction chromatographic packing materials based on inorganic matrix].

Based on inorganic matrix controlled pore glass (CPG) and macro-pore silica sphere, by using polyethylene glycol (PEG 1000) as a ligand, a preparation method of hydrophobic interaction chromatographic (HIC) packing material was improved by adding a proper catalyst during the bonding process. The packing material can be synthesized in a scale-up batch, for example 150g for each batch, both for analytical and preparative columns. The retention of proteins, such as cytochrome C (Cyt-C), chymotrypsingen-A (Chy-A), lysozyme (Lys) and ribonuclease(Rnase), is increased with the increasing of (NH4)2SO4 concentration in the eluant 2.5 mol/L of salt concentration for the mobile phase was chosen by considering the separation efficiency and equipment life. After comparing the effect of pH for the retention of proteins it is found that the proteins are well separated at pH 7. The time of linear gradient elution program was optimized in considering the separation efficiency and speed. It is better to take 30 minutes of the gradient program for the separation. Six standard proteins can be well separated with the high-performance HIC column in the linear gradient elution program from 2.5 to 0 mol/L of (NH4)2SO4 in 50 mmol/L of phosphate buffer solution within 30 minutes. Cyt-C, Rnase, Lys and Chy-A can be separated by the HIC column based on CPG matrix. Six proteins, Cyt-C, Rnase, Lys, Chy-A, insulin(Ins) and lipase (Lip) can be well separated on the column based on silica matrix with gradient elution program. The recovery of trypsin detected with BAEE method is over 95% after purification with the HIC column.

Chromatography↗

PubMed1997

[Preparation and characterization of sinopak-s-DEAE weak-anion exchange packing for high performance liquid chromatography].

High-performance ion exchange chromatography (HPIEC) is extensively used in the separation of peptides and proteins, especially in the biotechnology process. The principle of separation of proteins is based on the changes of pH and salt concentration in the mobile phase for the chromatographic model. A new synthetic method with the help of a catalyst for the bounding of diethylaminoethyl group on a home-made macro-pore silica sphere (the trade mark is Sinopak-s, with sphere size of 5 microm and pore diameter of 100 nm) was developed in our laboratory for the application of the scale-up separation of biotechnological target products in China. The Sinopak-s-DEAE weak anion ion exchange matrix for HPLC was prepared and characterized with various proteins. The pH value and reaction time were discussed for the reaction efficiency of ligand to the silica sphere. The coverage of the DEAE ligand on the silica surface were among 1.6 to 2.1 micromol/m2 for six batches of packings. The influences of the pH value and the salt concentration in mobile phase upon the retention of proteins on the DEAE column were also discussed. A bio-activity recovery up to 98% for trypsin was arrived after purification with the DEAE column under the chosen chromatographic conditions. The capacity of matrix for BSA was 80 mg/g. The column was successfully applied to separate a mixture of several standard proteins in a linear gradient elution condition from 0 to 0.4 mol/L of NaCl in a 50 mmol/L of Tris/HCl buffer (pH 7.0) at 1.0 mL/min flow rate and detected at 280 nm wavelength.

Anion Exchange Resins↗

PubMed1997

Synergistic cofactor function of factor V and protein S to activated protein C in the inactivation of the factor VIIIa - factor IXa complex -- species specific interactions of components of the protein C anticoagulant system.

Human factor V has been shown not only to be a precursor to procoagulant factor Va but also to express anticoagulant properties. Thus, factor V was recently found to potentiate the effect of protein S as cofactor to activated protein C (APC) in the inactivation of the factor VIIIa-factor IXa complex. The purpose of this study was to determine whether the APC-cofactor function of factor V was also expressed in the bovine protein C system and to elucidate the molecular background for the species specificity of APC. For this purpose, the effects of protein S and factor V on APC-mediated inactivation of factor VIIIa were studied using purified APC, protein S and factor V of human and bovine origin. The factor VIIIa investigated here was part of a Xase complex (i.e. factor IXa, factor VIIIa, phospholipid and calcium) and the APC-mediated inhibition of factor VIIIa was monitored by the ability of the Xase complex to activate factor X. Synergistic APC-cofactor function of factor V and protein S was demonstrated in the bovine system. The effect of bovine APC was potentiated by bovine protein S but not by human protein S, whereas both human or bovine protein S stimulated the function of human APC. Factor V did not express species specificity in its APC-cofactor activity even though bovine factor V was more potent than its human counterpart. Recombinant human/bovine protein S chimeras were used to demonstrate that the thrombin sensitive region and first epidermal growth factor-like module of protein S determine the species specificity of the APC-protein S interaction. In conclusion, both human and bovine factor V were found to express APC-cofactor activity which depends on the presence of protein S. The species specificity of APC was shown to be caused by the interaction between APC and protein S.

Animals↗

PubMed1997

Oltipraz chemoprevention trial in Qidong, Jiangsu Province, People's Republic of China.

Oltipraz has been used clinically in many regions of the world as an antischistosomal agent and is an effective inhibitor of aflatoxin hepatocarcinogenesis in rats. This chemopreventive action of oltipraz results primarily from an altered balance in aflatoxin metabolic activation and detoxication. In 1995, a randomized, placebo-controlled, double-blind intervention was conducted in residents of Qidong, People's Republic of China, who are at high risk for exposure to aflatoxin and development of hepatocellular carcinoma. The major study objectives were to define a dose and schedule for oltipraz that would reduce levels of aflatoxin biomarkers in biofluids of the participants, and to further characterize dose-limiting side effects. Two hundred thirty-four healthy eligible individuals, including those infected with HBV, were randomized to receive either 125 mg oltipraz daily, 500 mg oltipraz weekly, or placebo. Blood and urine specimens were collected to monitor potential toxicities and evaluate biomarkers over the 8-week intervention and subsequent 8-week follow-up periods. Overall, compliance in the intervention was excellent; approximately 85% of the participants completed the study. Objective evaluation of adverse events was greatly facilitated by inclusion of a placebo arm in the study design. A syndrome involving numbness, tingling, and pain in the fingertips was the only event that occurred more frequently among the active groups (18 and 14% of the daily 125 mg and weekly 500 mg arms, respectively) compared to placebo (3%). These symptoms were reversible and could be relieved with non-steroidal antiinflammatory agents. A more complete understanding of the chemopreventive utility of oltipraz awaits completion of an assessment of the efficacy of oltipraz in modulating levels of aflatoxin biomarkers.

Animals↗

PubMed1997

Antiganglioside antibodies in cerebrospinal fluid of children with neuropsychiatric lupus erythematosus.

OBJECTIVE: To determine antiganglioside antibodies (AGA) in cerebrospinal fluid (CSF) of children with neuropsychiatric lupus erythematosus (NPLE), and to investigate their association with clinical manifestations and other laboratory tests. METHODS: An enzyme linked immunoabsorbent assay was used to detect AGA in 22 CSF samples obtained from 18 children with systemic lupus erythematosus (SLE). These patients were further classified into clinical active NPLE (9 patients) and SLE (9 patients) groups. Indirect immunofluorescent assay was used for determination of CSF antinucleus antibodies (ANA). RESULTS: AGA could be found in CSF of all the 9 active NPLE children who had neuropsychiatric manifestations within 6 months before or after AGA was tested. A clear association was observed between AGA and brain CT scan. No detectable ANA was found in CSF samples even though high titer of ANA was present in corresponding serum samples of SLE patients. CONCLUSION: Detection of AGAs in CSF, more sensitive and specific than routine CSF examination and EEG, and positively associated with brain CT scan, is a simple and practical test for early judgment of childhood NPLE.

Adolescent↗

PubMed1997

[Effect of Ganoderma japonicum (Fr.) Lloyd mixture on experimental thrombosis].

The therapeutic effect of Ganoderma japonicum(Fr.) Lloyd mixture on thrombosis and its mechanism were studied. The results showed that Ganoderma japonicum(Fr.) Lloyd mixture inhibited thrombus formation in vitro and in vivo, the thrombus weight and length formed in the rabbit common carotid artery and external jugular vein were significantly decreased in the experimental group compared with the control (P < 0.01). The results suggest that Ganoderma japonicum(Fr.) Lloyed mixture has anti-thrombotic effect, blood coagulation and platelet activation were inhibited, and the ability of vascular endothelial cells against the process of thrombosis was enhanced.

Animals↗

PubMed1997

[Effect of monoclonal antibody against human tissue factor pathway inhibitor on plasma coagulation time].

The purpose of this study was to evaluate the influences of the monoclonal antibody against human tissue factor pathway inhibitor (TFPI), McAb4F8, on prothrombin time (PT) and activated partial thromboplatin time (APTT). The results showed that PT and APTT were prolonged by exogenous TFPI. Dilute thromboplastin coagulation time was shortened with a dose-dependent manner by McAb4f8. Low molecular weight heparin (LMWH) prolonged significantly PT and APTT, and this effect ws weakened by an antibody against human AT III. McAb4F8 was also proved to shorten dilute thromboplastin coagulation time of factor IX deficient plasma. These results indicated that the tissue factor pathway plays an important role not only in physiological coagulation but also in hemorrhage of hemophilia.

Animals↗

PubMed1997

[Effects of aprotinin on heparinized whole blood activated clotting time and whole blood prothrombin time].

When aprotinin is used during cardiopulmonary bypass, there is a prolongation of the activated clotting time (ACT), which is used to monitor heparinization. The aim of this study was to observe the effects of aprotinin and heparin on whole blood ACT and whole blood prothrombin time (BPT). The results showed that when kaolin was used as the contact activator, the intrinsic clotting system was also inhibited by aprotinin, the observed ACTs with various dose aprotinin and concomitant heparin were significantly prolonged (Q = 0.757, P < 0.01). There was a dose-dependent prolongation of BPT by heparin (r = 0.985, P < 0.01). However, the heparin-mediated prolongation of BPT was not enhanced by aprotinin. The authors conclude that aprotinin prolongs heparinized whole blood activated clotting time but was not whole blood prothrombin time.

Adult↗

PubMed1996

Dis3, implicated in mitotic control, binds directly to Ran and enhances the GEF activity of RCC1.

Using the two-hybrid method, we isolated a Saccharomyces cerevisiae cDNA encoding a protein homologous to Schizosaccharomyces pombe protein Dis3sp, using as bait, human GTPase Ran. The DIS3 gene is essential for viability and complements S.pombe mutant dis3-54 which is defective in mitosis. Although Dis3sc has no homology to RanBP1, it bound directly to Ran and the S.cerevisiae Ran homologue Cnr1, but not to the S.cerevisiae RCC1 homologue Srm1. Upon binding to Ran with a 1:1 molar ratio, Dis3sc enhanced a nucleotide-releasing activity of RCC1 on Ran. In the presence of Dis3sc, the K(m) of RCC1 on Ran decreased by half, while the kcat was unchanged. In vivo, Dis3sp was present as oligomers of M(r) 670-200 kDa as previously reported, and the 200 kDa oligomer of Dis3sp was found to include Spi1 and Pim1, the S.pombe homologues of Ran and RCC1, respectively. Although the biological function of the heterotrimeric oligomer consisting of Dis3, Spi1 and Pim1 is unknown, our results indicate that Dis3 is a component of the RCC1-Ran pathway.

Amino Acid Sequence↗