Biomedical subjects

X He

Publications and source records attributed to X He.

At least 271 records · Page 15Linked to original sources

PubMed1998

The identification of cDNAs that affect the mitosis-to-interphase transition in Schizosaccharomyces pombe, including sbp1, which encodes a spi1p-GTP-binding protein.

Perturbations of the spi1p GTPase system in fission yeast, caused by mutation or overexpression of several regulatory proteins, result in a unique terminal phenotype that includes condensed chromosomes, a wide medial septum, and a fragmented nuclear envelope. To identify potential regulators or targets of the spi1p GTPase system, a screen for cDNAs whose overexpression results in this terminal phenotype was conducted, and seven clones that represent three genes, named med1, med2, and med3 (mitotic exit defect), were identified. Their genetic interaction with the spi1p GTPase system was established by showing that the spi1p guanine nucleotide exchange factor mutant pim1-d1ts was hypersensitive to their overexpression. med1 encodes a homologue of the human Ran-binding protein, RanBP1, and has been renamed sbp1 (spi1-binding protein). sbp1p binds to spi1p-GTP and costimulates the GTPase-activating protein (GAP)-catalyzed GTPase activity. Cells in which sbp1p is depleted or overproduced phenocopy cells in which the balance between spi1p-GTP and spi1p-GDP is perturbed by other means. Therefore, sbp1p mediates and/or regulates the essential functions of the spi1p GTPase system. med2 and med3 encode novel fission yeast proteins that, based on our phenotypic analyses, are likely to identify additional regulators or effectors of the spi1p GTPase system.

Amino Acid Sequence↗

PubMed1998

Isolation and characterization of new fission yeast cytokinesis mutants.

Schizosaccharomyces pombe is an excellent organism in which to study cytokinesis as it divides by medial fission using an F-actin contractile ring. To enhance our understanding of the cell division process, a large genetic screen was carried out in which 17 genetic loci essential for cytokinesis were identified, 5 of which are novel. Mutants identifying three genes, rng3(+), rng4(+), and rng5(+), were defective in organizing an actin contractile ring. Four mutants defective in septum deposition, septum initiation defective (sid)1, sid2, sid3, and sid4, were also identified and characterized. Genetic analyses revealed that the sid mutants display strong negative interactions with the previously described septation mutants cdc7-24, cdc11-123, and cdc14-118. The rng5(+), sid2(+), and sid3(+) genes were cloned and shown to encode Myo2p (a myosin heavy chain), a protein kinase related to budding yeast Dbf2p, and Spg1p, a GTP binding protein that is a member of the ras superfamily of GTPases, respectively. The ability of Spg1p to promote septum formation from any point in the cell cycle depends on the activity of Sid4p. In addition, we have characterized a phenotype that has not been described previously in cytokinesis mutants, namely the failure to reorganize actin patches to the medial region of the cell in preparation for septum formation.

Actins↗

PubMed1998

Identification of epitopes in cucumber mosaic virus using a phage-displayed random peptide library.

Antigenic sites in the cucumber mosaic virus (CMV) coat protein (CP) have been identified using a polyclonal antiserum prepared against glutaraldehyde-fixed virions. Antibodies were used to screen a random peptide library of heptamers displayed on the surface of a bacteriophage. Eight of 36 (22%) sequenced phage clones had inserts resembling a putative virion surface domain of the CMV CP. This region has the sequence LETDEL, corresponding to amino acids 194-199 in the Fny-CMV CP. The binding of phage clones to Fny-CMV antiserum was inhibited by a synthetic peptide representing this region. Six of 36 (17%) phage clones contained sequences corresponding to a C-terminal sequence in the Fny-CMV CP, which is thought to be internal in assembled virions. This sequence, EHQRIPTSGV, represents amino acids 206-215 and all but the P residue were observed in at least one clone. Four of 36 (11%) sequenced phage clones carried sequences that matched a portion of the sequence RLLLPDSV, corresponding to amino acids 89-96 in the Fny-CMV CP. This region was also identified as the antigenic site recognized by a monoclonal antibody (MAb23C10E4). Eleven percent of the phage (4 of 36) contained sequences matching at least three amino acids of the N-terminal region in the CMV CP. The positions of the antigenic sites seen in this study are consistent with a predicted structure for the CMV CP.

Antibodies, Monoclonal↗

PubMed1998

Role of macrophages in acute murine cytomegalovirus infection.

It has been recognized that macrophages play an important role in controlling virus infection in experimental animal models. To evaluate the role of macrophages in acute murine cytomegalovirus infection, macrophages in the spleen and the liver were eliminated by an intravenous injection of liposomes containing a cytolytic agent, dichloromethylene diphosphonate. The depletion of macrophages led to a significant increase of virus titer in the spleen and lungs in both susceptible BALB/c and resistant C57BL/6 mice during the first three days after intravenous infection. In the spleen, the increase of virus titer in macrophage-depleted BALB/c mice was much greater than that in NK cell-depleted mice. These results suggest that macrophages contribute to protection mainly by the mechanisms which are independent of NK cells during the first three days after infection. The increase of virus titer in macrophage-depleted C57BL/6 mice was as great as that in NK cell-depleted mice because of the high contribution of NK cells to protection in C57BL/6 mice. In the liver in both strains of mice, the effects of macrophage depletion on virus titer were not as much as those in the spleen and lungs. Furthermore, the local depletion of peritoneal macrophages resulted in a great increase of virus titer in the spleen at three days after intraperitoneal infection. We conclude that macrophages greatly contribute to decreasing the virus load in some organs possibly through either or both intrinsic and extrinsic mechanisms in the early phase of primary infection with murine cytomegalovirus.

Acute Disease↗

PubMed1998

Activation of c-myc gene expression by tumor-derived p53 mutants requires a discrete C-terminal domain.

Mutation of the p53 tumor suppressor gene is the most common genetic alteration in human cancer, and tumors that express mutant p53 may be more aggressive and have a worse prognosis than p53-null cancers. Mutant p53 enhances tumorigenicity in the absence of a transdominant negative mechanism, and this tumor-promoting activity correlates with its ability to transactivate reporter genes in transient transfection assays. However, the mechanism by which mutant p53 functions in transactivation and its endogenous cellular targets that promote tumorigenicity are unknown. Here we report that (i) mutant p53 can regulate the expression of the endogenous c-myc gene and is a potent activator of the c-myc promoter; (ii) the region of mutant p53 responsiveness in the c-myc gene has been mapped to the 3' end of exon 1; (iii) the mutant p53 response region is position and orientation dependent and therefore does not function as an enhancer; and (iv) transactivation by mutant p53 requires the C terminus, which is not essential for wild-type p53 transactivation. These data suggest that it may be possible to selectively inhibit mutant p53 gain of function and consequently reduce the tumorigenic potential of cancer cells. A possible mechanism for transactivation of the c-myc gene by mutant p53 is proposed.

Animals↗

PubMed1998

Intermediate myasthenia syndrome following acute organophosphates poisoning--an analysis of 21 cases.

1. Twenty-one cases out of 272 patients of acute organophosphates poisoning were diagnosed as intermediate syndrome (IMS) with a prevalence at 7.7%. The responsible OP insecticides included parathion, omethoate and some OP containing pesticide mixtures. IMS occurred mainly in severe OP poisoning patients who recovered from the acute cholinergic crisis at 7-75 h after the onset of acute poisoning. 2. Muscular weakness appeared in the following three categories of muscles: (1) neck flexors and proximal limb muscles; (2) muscles innervated by motor cranial nerves and/or (3) respiratory muscles. Blood acetylcholinesterase activity was persistently inhibited. Electroneuromyography (ENMG) with repetitive nerve stimulation (RNS) at frequencies of 20 Hz or 30 Hz in seven patients showed decrements of common muscle action potentials during the presence of myasthenia in five patients and became normal when their muscle strength recovered. 3. Mild IMS recovered within 2-7 days and had a favorable prognosis. Severe IMS patients with respiratory paralysis needed immediate endotracheal intubation and mechanical ventilation. Recovery of weakness of the respiratory muscles and proximal limb muscles took longer, the slowest being 30 days. Four of the patients died of respiratory paralysis and the fatality rate was 19%. 4. The mechanism of IMS remains to be further investigated. The RNS/ENMG changes indicate a post-synaptic block at the neuromuscular junctions. 5. In order to promote the recognition of this syndrome, we proposed to name the syndrome as Intermediate Myasthenia Syndrome (IMS).

Adolescent↗

PubMed1998

Mph1, a member of the Mps1-like family of dual specificity protein kinases, is required for the spindle checkpoint in S. pombe.

The spindle assembly checkpoint pathway is not essential for normal mitosis but ensures accurate nuclear division by blocking the metaphase to anaphase transition in response to a defective spindle. Here, we report the isolation of a new spindle checkpoint gene, mph1 (Mps1p-like pombe homolog), in the fission yeast Schizosaccharomyces pombe, that is required for checkpoint activation in response to spindle defects. mph1 functions upstream of mad2, a previously characterized component of the spindle checkpoint. Overexpression of mph1, like overexpression of mad2, mimics activation of the checkpoint and imposes a metaphase arrest. mph1 protein shares sequence similarity with Mps1p, a dual specificity kinase that functions in the spindle checkpoint of the budding yeast Saccharomyces cerevisiae. Complementation analysis demonstrates that mph1 and Mps1p are functionally related. They differ in that Mps1p, but not mph1, has an additional essential role in spindle pole body duplication. We propose that mph1 is the MPS1 equivalent in the spindle checkpoint pathway but not in the SPB duplication pathway. Overexpression of mad2 does not require mph1 to impose a metaphase arrest, which indicates a mechanism of spindle checkpoint activation other than mph1/Mps1p kinase-dependent phosphorylation. In the same screen which led to the isolation of mad2 and mph1, we also isolated dph1, a cDNA that encodes a protein 46% identical to an S. cerevisiae SPB duplication protein, Dsk2p. Our initial characterization indicates that S.p. dph1 and S.c. DSK2 are functionally similar. Together these results suggest that the budding and fission yeasts share common elements for SPB duplication, despite differences in SPB structure and the timing of SPB duplication relative to mitotic entry.

Amino Acid Sequence↗

PubMed1998

Diagnosis and classification of hepatic echinococcosis by ultrasonography.

OBJECTIVE: To make an early and correct diagnosis of hepatic echinococcosis. METHODS: A total of 1092 patients with hepatic echinococcosis underwent operation in our hospital between 1984 and 1995. Of these patients, 427 (39.1%) were cases with complications, including secondary infection, rupture, obstructive jaundice, anaphylactic shock, disseminated implantation with resultant multiple echinococcosis and portal hypertension. The ultrasonic examination has been generally used in clinical practice for comprehensive evaluation which can dectedct the preoperative diagnostic accuracy rate. RESULTS: B-mode ultrasonography can be used not only to detect the location, dimension and pathological characteristics of hydatid cyst but also to show the pathological changes of various complications caused by echinococcosis. Seven patterns specific ultrasonic scanning images were revealed. In this series the diagnostic accuracy rate reached 98.8%. CONCLUSIONS: Ultrasonic examination is harmless to human body, and has been widely used in combination with immunological tests in clinical and epidemiological studies to detect the asymptomatic parasite carriers in early stage and to improve the preoperative diagnostic accuracy rate.

Echinococcosis, Hepatic↗

PubMed1998

[Relationship between clinical manifestation and pathology in pediatric renal diseases].

To elevate the clinical diagnosis and pathological compatibility of pediatric kidney diseases. Pathological changes from 101 cases of pediatric renal diseases were studied, covering 13 diseases entities, including glomerulo-nephritis, simple nephrotic syndrome, nephritic nephrotic syndrome etc. The technique of tru-cut biopsy under the guidance of B ultrasonogram was used in renal biopsy. The renal puncture biopsy was 100% satisfactory. Pathological changes involved 12 pathological types. MsPGN were the most commonly seen (39.6%), followed by MPGN and ICPGN (12.87% and 10.89%) respectively. It was found that children with similar clinical manifestation may possess different pathological changes, while the same pathological entity may present multiple clinical manifestation. The results suggest that renal biopsy pathological diagnosis is important in the diagnosis, treatment and prediction of prognosis in pediatric renal disease.

Adolescent↗

PubMed1998

[Effect of manganese on the growth and development of rat offspring].

Effects of Manganese exposure to pregnant rats on the growth and development of their offsprings were as follows: (1) the gain of body weight and brain weight in the high dose Mn-exposed offspring was significantly lower but the ratio of brain to body weight was significantly higher; (2) in Morris Water Maze Test, the average latency to find the hidden platform in the high dose Mn-exposed offsprings was obviously reduced during the first 5 days. But on the non-platform test day, a much longer length of swimming in the quadrant in which the hidden platform was located previously, although no difference was found for the total distance between them; (3) the immunoreactivity of glial fibrillary acid protein and the average density of its products in hippocampus of both the low and high dose Mn-exposed groups, especially of the high dose one, was significantly higher than that of the control group.

Animals↗

PubMed1998

[The expression of CD11a and CD11b on leucocytes in cerebral thrombosis].

This study sought to understand the mechanism for the increased adhesion of leucocytes and endothelial cells in ischemic stroke. 20 patients with acute cerebral thrombosis and 20 healthy subjects as controls for expression of CD11a and CD11b (adhesion molecules on surface of leucocytes) were tested in vitro by flow cytometry (FCM) method. The results showed that compared with the control group, the patient group had significantly higher rates for expression of CD11a on monocytes, granulocytes and lymphocytes (P < 0.05). The CD11b expression in the patient group was positively elevated on monocytes and granulocytes (P < 0.05), but it was of lower positive rate on lymphocytes and no statistical difference was noted between the patient and control groups. These indicate that the expression of CD11a and CD11b on leucocytes increases in cerebral ischemic damage; thus adhesion of leucocytes and endothelial cells obviously increases. This change may aggravate post-ischemic delayed neuronal death.

Adult↗

PubMed1998

[Bcl-2 gene expression in endometrial carcinoma].

OBJECTIVE: To evaluate the relationship between bcl-2 gene and endometrial carcinoma. METHODS: Immunohistochemical staining was performed on formalin-fixed paraffin-embedded tissue sections. A monoclonal antibody to the bcl-2 gene product was used, the signal was detected using a streptavidin-biotin complex with aminoethylcarbazole. There were 15 cases of endometrial atypical hyperplasia and 50 cases of endometrial carcinoma examined. RESULTS: Bcl-2 expression was high in endometrial atypical hyperplasia, whereas bcl-2 expression was low in endometrial carcinoma. In endometrial carcinoma, with progression of clinical stage, decreased histologic grade and deepening of cancer invasion, the positive rate of bcl-2 expression was correspondingly decreased. CONCLUSION: Bcl-2 plays a role in the genesis of endometrial carcinoma especially at the initial stage.

Adult↗

PubMed1998

[Scavenging action of shengmaiyin decoction on hydroxyl radical].

A study has been made on the scavenging action of Shengmaiyin Decoction and its ingredients Radix Ginseng, Radix Ophiopogonis and Fructus Schisandrae on hydroxyl radical, as well as on the relationship between the decoction and its ingredients using ESR spin-trapping. The results indicate that the decoction is better in antioxidation than its ingredients.

Drug Combinations↗

PubMed1998

Preparation and characterization of monoclonal antibody against recombinant human tissue factor pathway inhibitor.

OBJECTIVE: To prepare and identify monoclonal antibody (McAb) against recombinant human tissue factor pathway inhibitor (rhTFPI) and to use it for measurement of TFPI by ELISA, and to evaluate the effects of the McAb on dilute prothrombin time (PT) and activated partial thromboplastin time (APTT). METHODS: After intrasplenic immunization of Balb/c mouse with TFPI, hybridoma technique was used to raise monoclonal antibody against rhTFPI. The McAb was well-characterized and labelled with horseradish peroxidase (HRP) by using assay of TFPI in ELISA. Furthermore, the McAb was added to normal and factor IX deficient plasma for observation of dilute PT and APTT. RESULTS: Two hybridomas (4F4, 4F8) secreting McAb against TFPI were established. The Ig class and subclass of the McAb purified from 4F8 was IgG1. Immunoblotting results indicated that the McAb4F8 only recognized a single band of TFPI with molecular weight of 34.8 KD. The results of Sandwich enzyme-linked immunosorbent assay (ELISA) by using the HRP labelled McAb4F8 showed that the mean of TFPI in normal human plasma is 103.2 +/- 11.5 micrograms/L. The McAb 4F8 was also proved to shorten markedly dilute prothrombin time of factor IX deficient plasma and normal plasma. CONCLUSIONS: We established two hybridomas cell lines (4F4, 4F8) and obtained the McAb4F8 against TFPI and reported the levels of TFPI in healthy adult human plasma by Sandwich ELISA with HRP labelled McAb4F8 in Chinese.

Animals↗

PubMed1998

[Study on comprehensive assessment in selection of special work personnel].

A comprehensive assessment method combining fuzzy set theory with traditional approaches is introduced. Method of index assessment and comprehensive assessment along with a fuzzy assessment model are presented. As an example, three fuzzy algorithms are used to assess 6 candidates. Calculated results show that the combination of fuzzy logic and experience of experts is feasible and can deal with unprecise information more effectively as well as the aggregation of fuzzy information and precise data. The new method described in this paper is accurate and the speed of decision-making is much improved as compared with the conventional approaches.

Aerospace Medicine↗

PubMed1998

[Induction differentiation by a new third generation retinoid R9158 on human acute promyelocytic leukemia cell line, NB4].

OBJECTIVE: In order to investigate the differentiation of 3',5'-ditertiary-butiary-4'-methoxy-carboxyl chalcone (R9158) on the acute promyelocytic leukemia NB4 cells. METHODS: By inditifying the function, morphology and karyotype of NB4 cells induced by R9158. RESULTS: Our results showed that R9158 or all-trans retinoic acid (RA) significantly inhibited the growth and colony formation of acute promyelocytic leukemia NB4 cells, while NBT-reduction (a functional differentiation marker of granulocytic) was dramatically increased when the cells were exposed to R9158 at 10(-9)-10(-6) mol/L, and the NBT positive cells reached about 97.5% at 10(-6) mol/L after 6 days expouse. The ED50 of NBT-reduction was achieved at concentration of 3.9 x 10(-9) mol/L and 2.8 x 10(-9) mol/L for R9158 and RA, respectively. Morphologically, most of the cells induced by R9158 and RA at 10(-6) mol/L were in the myelocytic or metamyelocytic stage and a few cells were in the banded or segmented stage. Cytogenetic analysis revealed that the karyotype of NB4 cells was subtetraploid and the chromosome numbers were in the range of 71-99, when NB4 cells were treated with R9158 or RA for 3-6 days, the abnormal polyploid chromosome numbers decreased to 72.9 +/- 6.9 (P < 0.01) or 68.5 +/- 7.0 (P < 0.01), but the t(15;17) translation did not disappear. CONCLUSIONS: R9158 has significant effects on the differentiation of NB4 cells.

Aneuploidy↗

PubMed1998

[Culture of human trabecular meshwork cells and the cell characteristics of immunohistochemical studies].

OBJECTIVE: To look for better cultural methods in order to obtain numerous human trabecular cells in vitro for glaucoma experimental studies, and describe the immunohistochemical characteristics of the cells. METHOD: Human trabecular meshwork cells were cultured, then 4 monoclonal antibodies were used for immunohistochemical stains of the cultured cells. RESULTS: At the primary period, the growth of human trabecular cells was obviously slower than that of cows and pigs. The immunohistochemical stains showed that the cells presented positive reactions to neuronal specific enolase (NSE) and vimentin and negative reactions to factor VIII related antigen (VIIIR:Ag) and desmin. CONCLUSIONS: The culture of human trabecular meshwork cells in vitro needs more careful and better cultural conditions. The cells originally are derived from embryonic neural crest, not from mesodermal endothelium of blood vessels. There is middle filament vimentin and no desmin in the cells.

Cell Division↗

PubMed1998

[Synthesis and vasodilative activities of benzamide derivatives].

Twenty two benzamide derivatives were synthesized of which twenty one were not reported before. Vasodilative activity screening in vitro has shown that most of the compounds possess various activities, among which compound H1, H11, H17, E1, E3 demonstrated a superior pharmacological profile to the lead compound when inhibiting effect on the noradrenaline (10(-7) mol.L-1) induced contraction of rat aortic strip was chosen as the evaluation criterion, while H7,15, E7 exerted significant inhibiting action toward 85.7 mmol.L-1 KCl induced contraction of rat aortic strip. Further evaluation assays for their KCO potentials showed that E1 might be an ATP sensitive KCO. Preliminary structure-activity relationships of this kind of aromatic amides are discussed herein.

Animals↗