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Biomedical subjects

Y Dong

Publications and source records attributed to Y Dong.

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

[Analysis of C5 fractions and carbonyl compounds by capillary gas chromatography].

We used two capillary columns with different characters--SE-54 (30 m x 0.25 mm) and Squalane (92 m x 0.24 mm) to analyse C5 fractions and carbonyl compounds in the mixtures of complex chemical composition. The physical properties of some components are very similar, especially for 1,3-cyclopentadiene and cis-1,3-pentadiene. 1,3-Cyclopentadiene in the feed will directly affect the activity of catalyst. In the past we only used SE-54 column to separate 1,3-cyclopentadiene and cis-1,3-pentadiene, but the results were unsatisfactory. Later we found that squalane column could separate them fairly good, but it could not yet separate dicyclopentadiene from 1,3-cyclopentadiene and carbonyl compounds in C5 fractions very well. In this work SE-54 capillary column and squalane capillary column were used together to analyse C5 fractions, and SE-54 column was used to analyse carbonyl compounds. The results are satisfactory.

Carbon↗
PubMed1999

[Study on the effects of taxol on Hep-2 cell lines in larynx carcinoma].

OBJECTIVE: To investigate the sensitivity of Hep-2 cell lines in larynx squamous cell carcinoma to the taxol in vitro and to provide experimental basis for clinical therapy. METHOD: Techniques of cell culture and randomized blank-contrast design were used. The degree and dose-dependency of taxol which induced growth inhibition in Hep-2 cell lines were observed and the alteration of cell cycle was analysed by flow cytomethy. RESULT: All cells died at the concentration of taxol 1 x 10(-8) M; growth inhibition was observed clearly at the concentration of 5 x 10(-9) M and 2.5 x 10(-9) M. Flow cytometric data showed a G0/G1 arrest and apoptosis (28.96%) in two cell lines after exposure to taxol for 48 h at low and medium concentrations. CONCLUSION: There is a high sensitivity of Hep-2 cell to taxol in vitro. The cells show G0/G1 arrest and apoptosis. This results may provide reliable guidance for treating largnx carcinoma.

Antineoplastic Agents, Phytogenic↗
PubMed1998

Molecular cloning and characterization of LR3, a novel LDL receptor family protein with mitogenic activity.

We report molecular cloning and initial functional characterization of a novel member of the low density lipoprotein receptor (LDLR) gene family. The cDNA was isolated from a human osteoblast cDNA library and encoded a 1,615 amino acids protein designated as LR3. It has, in the extracellular region, a cluster of three LDLR ligand binding repeats at a juxtamembrane position and four EGF precursor homology domains separated by YWTD spacer repeats. The entire ectodomain shares the same modular organization with the middle portion of the extracellular regions of two LDLR family members, LDLR-related protein (LRP), and gp330/megalin. LR3 mRNA was expressed in most of the adult and fetal tissues examined. The highest expression level was seen in aorta. In human osteosarcoma cells examined, LR3 mRNA was highly enriched in TE85 cells, moderately expressed in MG63 cells and primary human osteoblasts, and undetectable in SaOS-2 cells. NIH 3T3 cells transfected with either full length LR3 or its ectodomain showed significantly increased proliferation, whereas transfection of intracellular domain had no proliferative effect. We predict that LR3 is a multi-functional protein with potential mitogenic activity.

3T3 Cells↗
PubMed1998

Analysis of primate renal allografts after T-cell depletion with anti-CD3-CRM9.

BACKGROUND: FN18-CRM9 is a CD3-specific immunotoxin that is capable of depleting CD3+ T cells. Pretreatment of rhesus monkeys with this agent before transplantation can induce donor-specific tolerance and "split tolerance" to renal allografts. METHODS: Heterotopic renal transplants were performed on monkeys that received posttransplant FN18-CRM9. Histological and immunohistological staining, as well as analysis of the intragraft cytokine profile by reverse transcriptase polymerase chain reaction, was performed on percutaneous allograft biopsies. RESULTS: Experimental monkeys had significant prolongation of allograft survival. Although an interstitial, mononuclear cell infiltrate was seen in all of the renal transplants, there was minimal evidence of acute cellular rejection. Histological evidence of alloantibody-mediated damage was detected 3 to 5 months after transplantation in the monkeys treated with FN18-CRM9. Immunohistology demonstrated the reappearance of CD3+ and CD4+ T cells, as well as CD20+ B cells, in the grafts. Cytokine analysis demonstrated expression of interferon-gamma. An intact anti-donor IgG response was seen. CONCLUSION: Treatment of monkeys with FN18-CRM9 immediately after transplantation significantly prolongs renal allograft survival. Allograft biopsies demonstrate a lack of acute cellular rejection; however, alloantibody-mediated graft damage and rejection occur, with an intact anti-donor IgG response. The intragraft expression of the interferon-gamma may reflect this ongoing humoral rejection. These data suggest that even a brief period of T-cell allosensitization may lead to humorally mediated allograft damage. Efforts to achieve tolerance with posttransplant FN18-CRM9 will require modification of the protocol to deplete T cells before allosensitization exposure or to supplement the posttransplant immunomodification strategy.

Animals↗
PubMed1998

Evidence that HetR protein is an unusual serine-type protease.

The hetR gene plays a very important role in cell differentiation of heterocystous cyanobacteria. To understand the mechanism of the hetR gene product in regulation of heterocyst differentiation, the recombinant HetR protein (rHetR) was overproduced in Escherichia coli. Purified rHetR was unstable and degraded easily in solution. Phenylmethanesulfonyl fluoride, a serine-type protease inhibitor, prevented the degradation and was shown to modify covalently rHetR. Dansyl fluoride (DnsF), another serine-type protease inhibitor, also covalently modifies rHetR as shown by electrophoresis and electroblotting of the labeled rHetR and by MS. The labeling of rHetR with phenylmethanesulfonyl fluoride and DnsF was at the same site of rHetR and required Ca2+. S179N-rHetR, a mutant protein from strain 216 of Anabaena PCC 7120, which cannot differentiate heterocysts because of the mutation, was also overproduced and characterized. Although S170N-rHetR still can be labeled with DnsF, no proteolysis was observed, suggesting that Ser179 is involved in proteolytic activity. DnsF-labeled rHetR was digested with trypsin, and the labeled peptide was isolated and sequenced. The labeled peptide matches a sequence from HetR. These results show that HetR is a protease.

Amino Acid Sequence↗
PubMed1998

Functional implications of the 21-24 loop in recombinant prochymosin.

To investigate the role of the 21-24 (pepsin numbering) loop in prochymosin, the amino acid residues GTPP at positions 21 through 24 were replaced with GG, the equivalent loop residues from its homologous protein, penicillopepsin, or SG, GS by site-directed mutagenesis. The mutants except GTPP(21-24)GS could be expressed in Escherichia coli. Activation studies indicated that the refolded prochymosin mutants were capable of undergoing autocatalytic activation to produce pseudochymosin by cleaving its N-terminal 27 amino acid residues at pH 2. The resulting pseudochymosin mutants were able to convert into chymosin at pH 5.5 by further autocatalytic cleavage to remove additional 15 amino acid residues. These results demonstrate that the prochymosin analogs can fold into an active state from an unfolded state and that the pseudochymosin analogs can proceed in the transformation from one active form into another active form. Spectroscopic analyses revealed that after mutation the far UV CD spectrum of prochymosin was considerably modified, showing less negative ellipticity values, and the fluorescence emission intensities of prochymosin and pseudochymosin were remarkably reduced. The stabilities of prochymosin and pseudochymosin, especially, were dramatically decreased. The stabilization energy of prochymosin was reduced by 7-8 kJ/mol. The inactivation temperature of pseudochymosin was decreased by 15-20 degrees C. The wild-type pseudochymosin was stable at pH 1.5 and 6.5, whereas the mutants were completely inactivated at the same pH values. Taken together, it is reasonable to conclude that the 21-24 loop (GTPP) plays an important role in determining the stability of prochymosin and pseudochymosin, although the mutants with mutated loop (GG or SG) still can refold into an active conformation.

Animals↗
PubMed1998

Atrophy of the corpus callosum, cortical hypometabolism, and cognitive impairment in corticobasal degeneration.

OBJECTIVE: To investigate whether atrophy of the corpus callosum is associated with cognitive impairment and cerebral cortical hypometabolism in corticobasal degeneration. DESIGN: Prospective clinicoradiological correlation with magnetic resonance imaging and positron emission tomography. SETTING: A university hospital. PATIENTS: Eight right-handed patients with clinically diagnosed corticobasal degeneration (mean+/-SD age, 64+/-8 years). MAIN OUTCOME MEASURES: Midsagittal corpus callosum area-skull area ratio (on T1-weighted magnetic resonance images), the sum of the scaled scores of the 6 subtests on the Wechsler Adult Intelligence Scale-Revised (Digit Span, Arithmetic, Picture Arrangement, Object Assembly, Block Design, and Digit Symbol), and cerebral metabolic rate of glucose (measured with positron emission tomography by using fludeoxyglucose F 18 as a tracer). RESULTS: Compared with 36 age-matched right-handed control subjects, the patients had significantly decreased callosal area-skull area ratio. The reduction in this ratio was greatest in the middle half of the corpus callosum. The atrophy of the corpus callosum was accompanied by a decreased mean cortical glucose metabolic rate with hemispheric asymmetry and a decrease in the sum of the scaled subtest scores of the Wechsler Adult Intelligence Scale-Revised. CONCLUSIONS: Atrophy of the corpus callosum with middle predominance is present in corticobasal degeneration, and this atrophy is associated with cognitive impairment and cerebral cortical hypometabolism with hemispheric asymmetry. Atrophy of the corpus callosum might reflect the severity of the disconnection between cortical regions, and this may be an important factor in the development of cerebral cortical dysfunction in corticobasal degeneration.

Aged↗
PubMed1998

Tumor necrosis factor alpha, interleukin-6, interleukin-8, and interferon alpha in children with viral hepatitis.

To investigate the cellular immunological changes in children with viral hepatitis, interleukin 6 (IL-6), interleukin 8 (IL-8), interferon alpha (IFN alpha), and tumor necrosis factor alpha (TNF alpha) in supernatant of cultured peripheral blood mononuclear cells (PBMCs) of 49 children with hepatitis A, B or C were measured. The levels of IL-6, IL-8, TNF alpha in PBMCs of the 3 viral hepatitis groups were increased and the level of IFN alpha decreased as compared with those of normal control group. But there were no significant differences among the 3 viral hepatitis groups. It was concluded that cellular immunological disorders were related to the onset and the induced damage of the viral hepatitis in children.

Adolescent↗
PubMed1998

Cytomegalovirus infection in children's liver tissues.

Immunoperoxidase histochemical assay with monoclonal antibody against human cytomaglovirus (HCMV) was used to detect immediate early antigen (IEA) and early antigen (EA) of HCMV infection in liver tissue of 72 pediatric cases (34 autopsies and 38 biopsies). The HCMV antigen was positive in 25% (18/27). Among them, 12 cases were both HCMV-IEA and EA positive; 4 were HCMV-IEA positive and 2 HCMV-EA positive only. Liver HCMV infection rate in neonates, the infants with the age < 1 year and > 1 year was 8.0%, 60.0%, and 14.8%, respectively, indicating that liver HCMV infection occurred at various ages. The liver HCMV infection rate in different diseases was 50.0% in infantile hepatitis syndrome; 70.0% in extrabiliary malformation, and 12.5% in other hepatopathies, suggesting that infantile hepatitis syndrome and extrabiliary malformation were related with HCMV infection in liver tissues.

Antigens, Viral↗
PubMed1998

Detection and identification of enteroviruses RNA by using polymerase chain reaction.

For rapid diagnosis of enteroviral infection in clinic practice, we developed a reverse transcription and polymerase chain reaction (RT-PCR) assay. Primers homologous to the conserved 5' non-coding region were designed by analyzing enteroviral genomes, and then they were used to enzymatically amplify RNA from 31 prototype enteroviral strains and enteroviruses (EV) in cerebrospinal fluid (CSF) of 34 cases of aseptic meningitis and 11 cases of aseptic encephalitis. The RT-PCR products generated with these enteroviral primers were analyzed by agar gel electrophoresis and dot blot hybridization analysis. 31 EV strains showed an obvious monoclonal amplification band, and all dot blot hybridization results were positive. Four other viruses and cells cultured were all negative. The study of sensitivity of the RT-PCR showed that amplification production were positive to 10(-2)-10(-3) 50% tissue culture infective doses. With this assay, 21 (61.8%) of 34 aseptic meningitis and 8 (72.7%) of 11 aseptic encephalitis contained EV RNA in CSF samples. Two cases of meningitis and one of encephalitis with EV infection were still positive during convalescence. Our results suggest that this RT-PCR method was a fast, sensitive and specific technique for detection of common EV infection.

Cerebrospinal Fluid↗
PubMed1998

Detection of human papillomavirus (HPV) DNA in archival specimens of benign prostatic hyperplasia and prostatic cancer using a highly sensitive nested PCR method.

Human papillomavirus is thought to be an etiological factor for urological tumors such as penile cancer. However, there is much conflicting data surrounding prostatic cancer. We recently established a highly sensitive nested PCR method with consensus human papillomavirus (HPV) primers for the detection of many high-risk HPV types. HPV DNA from the long-control region (LCR) to E7 open reading frame was amplified with first primer pairs and subsequently amplified with second internal E6-E7 primers. Our nested PCR method could detect HPV16, 18, 31, 33, 35, 52, 58 and some undetermined HPV DNAs. Using this method, we investigated the existence of HPV DNA in formalin-fixed paraffin-embedded tissue of the prostate. We found HPV DNA in three of 71 specimens of benign prostatic hyperplasia (BPH) and in none of 38 prostatic carcinomas. These three samples were infected with HPV 16. These results suggest that HPV is not a causal factor for prostatic cancer and BPH.

Base Sequence↗
PubMed1998

Modulation of resuscitative effect of diaspirin cross-linked hemoglobin by L-NAME in rats.

Diaspirin Cross-linked Hemoglobin (DCLHb), a hemoglobin-based oxygen carrier, improves regional blood circulation and systemic hemodynamics in normal and hemorrhaged rats. The action of DCLHb is partly mediated by its scavenging effect on nitric oxide. This study was undertaken to determine the effect of DCLHb on nitric oxide mechanism in hemorrhagic conditions. We studied the modulation of cardiovascular effects of DCLHb by a nitric oxide synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME) in hemorrhaged rats. The base deficit, survival time, oxygen consumption, and blood circulation to the brain, heart, gastrointestinal tract, and kidneys were determined in 1) DCLHb (100 mg/kg, intravenously (i.v.), 2) L-NAME (2 mg/kg, i.v.), 3) L-NAME (2 mg/kg, i.v.) + DCLHb (100 mg/kg, i.v.), and 4) L-arginine (100 mg/kg/h, i.v.) + DCLHb (100 mg/kg, i.v.) treated rats. Hemorrhage was induced in urethane-anesthetized male rats by bleeding them at a rate of approximately .5 to 1 mL/min, until a mean arterial pressure of 35-40 mmHg was achieved. This blood pressure was maintained for 30 min. Sham-operated nonhemorrhaged rats survived for >300 min, whereas hemorrhaged rats survived for only 85+/-31 min. Hemorrhage significantly increased base deficit and decreased oxygen consumption. A significant decrease in heart rate, mean arterial pressure, cardiac output, stroke volume, and in blood flow to the gastrointestinal tract and kidneys was observed after hemorrhage. Resuscitation with DCLHb produced a significant increase in survival time, oxygen consumption, heart rate, mean arterial pressure, cardiac output, total peripheral resistance, and blood flow to the brain, heart, and kidneys. In contrast, resuscitation with L-NAME did not improve base deficit, survival time, oxygen consumption, systemic hemodynamics, or regional blood flow. L-arginine pretreatment did not affect DCLHb-induced resuscitation of hemorrhaged rats. Furthermore, L-NAME (pretreated or co-administered) attenuated the resuscitative effect of DCLHb. These data suggest that nitric oxide mechanism may not be the only mechanism involved in the resuscitative effect of DCLHb.

Animals↗
PubMed1998

Fluoroquinolone action against mycobacteria: effects of C-8 substituents on growth, survival, and resistance.

Fluoroquinolones trap gyrase on DNA as bacteriostatic complexes from which lethal DNA breaks are released. Substituents at the C-8 position increase activities of N-1-cyclopropyl fluoroquinolones against several bacterial species. In the present study, a C-8-methoxyl group improved bacteriostatic action against gyrA (gyrase-resistant) strains of Mycobacterium tuberculosis and M. bovis BCG. It also enhanced lethal action against gyrase mutants of M. bovis BCG. When cultures of M. smegmatis, M. bovis BCG, and M. tuberculosis were challenged with a C-8-methoxyl fluoroquinolone, no resistant mutant was recovered under conditions in which more than 1, 000 mutants were obtained with a C-8-H control. A C-8-bromo substituent also increased bacteriostatic and lethal activities against a gyrA mutant of M. bovis BCG. When lethal activity was normalized to bacteriostatic activity, the C-8-methoxyl compound was more bactericidal than its C-8-H control, while the C-8-bromo fluoroquinolone was not. The C-8-methoxyl compound was also found to be more effective than the C-8-bromo fluoroquinolone at reducing selection of resistant mutants when each was compared to a C-8-H control over a broad concentration range. These data indicate that a C-8-methoxyl substituent, which facilitates attack of first-step gyrase mutants, may help make fluoroquinolones effective antituberculosis agents.

Anti-Infective Agents↗