Biomedical subjects

K Luo

Publications and source records attributed to K Luo.

At least 37 records · Page 2Linked to original sources

PubMed2001

[Detection of positive-strand of transfusion transmitted virus fragment in the liver of cryptogenic hepatitis].

OBJECTIVE: To evaluate whether transfusion transmitted virus (TTV) replicates in the liver and to analyze the relationship between TTV and cryptogenic hepatitis. METHODS: A 3.2 kb TTV fragment was detected by nested polymerase chain reaction (PCR) in 31 serum samples of patients with cryptogenic hepatitis who came from a school where was in an outbreak area of cryptogenic hepatitis during 1996 and in 30 healthy individuals. A hybridization/nuclease protection assay was used to detect positive-strand TTV fragment from the liver specimens of the 7 patients. RESULTS: TTV DNA was detected in serum samples from 30 of 31 (96.9%) patients and from 18 of 30 (60%) healthy individuals, respectively. There was significant difference in the prevalence of TTV infection between the two groups. Based on hybridization/ nuclease protection assays, we detected positive-strand TTV fragment in all of 7 liver specimens of the patients. CONCLUSIONS: TTV is related possibly to cryptogenic hepatitis. TTV can replicate in the liver. Although TTV only causes mild liver damage, a few patients will suffer from chronic hepatitis.

Adult↗

PubMed2001

Enteric transmission of transfusion-transmitted virus.

OBJECTIVE: To detect the virus in the feces and sera of patients in an outbreak of enterically transmitted non-A, non-E hepatitis, and this review covers the epidemiologic features and experimental infection of this novel virus. DATA SOURCES: Data sources come from our own work on this subject, published and unpublished. STUDY SELECTION: Mainly our own work is included, and related literature is collected. RESULTS: In an outbreak of enterically transmitted non-A-E hepatitis among students, a total of 381 cases (60.7%) were documented. Viral fragments identical to transfusion transmitted virus (TTV) were detected in both serum and stool samples. Asymptomatic virus carriers among the staff had positive serum (32.1%) and feces (24.6%), clearly a potential source of infection. This viral infection prevalence in 2 remote villages in northern and southern China was 9.2% and 10.6%, respectively, suggesting that China is an endemic area. In this study, groups of 3 Rhesus monkeys were infected via oral or intravenous inoculation with patient feces. Two additional monkeys were infected by passage. The virus was detected in serum, peripheral blood mononuclear cell (PBMC), liver, spleen and small intestine, while the virus positive single strand, which might be a replicative intermediate, was only in liver, intestine and PBMC of all animals. CONCLUSIONS: This nonenveloped DNA virus might be transmitted both by blood and enteric routes. Considering its wide distribution and high prevalence, we suppose that nonparenteral transmission is more important.

Animals↗

PubMed2001

Th1/Th2 type cytokines in hepatitis B patients treated with interferon-alpha.

OBJECTIVE: To investigate the relationship between the expression of Th1/Th2 type cytokines and the effect of interferon-alpha therapy. METHODS: Th1/Th2 type cytokines were assayed by enzyme-linked immunosorbent assay (ELISA) and reverse transcription polymerase chain reaction (RT-PCR) on 23 patients with chronic hepatitis B who were treated with interferon-alpha. RESULTS: Levels of IFN-gamma in the supernatant of peripheral blood mononuclear cells (PBMC) cultures from the patients with hepatitis B were slightly lower than those of controls (P = 0.07). However, the levels of IL-4 were higher than those of controls (P = 0.01). Cytokines measurements during IFN-alpha treatment showed a trend to decreasing levels of IL-4 at 4, 12, and 24 weeks. Levels of IFN-gamma were slightly increased following IFN-alpha treatment (P = 0.09). In patients with a complete response to IFN-alpha, the levels of IFN-gamma were higher at 24 weeks following IFN-alpha treatment than that of pre-treatment (P = 0.04), and the levels of IL-4 decreased markedly at 12 and 24 weeks (P = 0.02, 0.03, respectively). mRNA expression positively correlated with the level of Th1/Th2 type cytokines in the supernatant. CONCLUSION: The expression of Th2 type cytokines is predominant in patients with chronic hepatitis B. Interferon-alpha therapy can modulate the balance of Th1/Th2 type cytokines, and this is related to its clinical effect. Levels of Th1/Th2 type cytokines could be a predictor of clinical response during Interferon-alpha treatment.

Antiviral Agents↗

PubMed2001

[Effects of air staging with absorbents on trace metal during coal combustion].

Staged combustion was carried out on laboratory-scale pulverized coal combustion with different absorbents. The experiment indicated staged combustion increased emission of submicron particles, which went against the control of trace elements, especially for those of high volatile elements, such as Cu, Ni. The thermodynamics calculation also indicate the transformation of trace metal was different with different atmosphere, suboxidized and reduced species were more easily formed under reduced condition. In both conditions, absorbents show a certain absorptive ability to trace metal, and different absorbent had different ability. For unstaged combustion, kaolinite was the best for Co, Cr and Ni; dolomite for Be, and CaO for Cu. But for under staged condition, HZ- dolomite was the best for Be, Cr and Ni; Kaolinite for Co and Cu.

Absorption↗

PubMed2000

Ski represses bone morphogenic protein signaling in Xenopus and mammalian cells.

The bone morphogenic proteins (BMPs) play important roles in vertebrate development. In Xenopus, BMPs act as epidermal inducers and also as negative regulators of neurogenesis. Antagonism of BMP signaling results in neuralization. BMPs signal through the cell-surface receptors and downstream Smad molecules. Upon stimulation with BMP, Smad1, Smad5, and Smad8 are phosphorylated by the activated BMP receptors, form a complex with Smad4, and translocate into the nucleus, where they regulate the expression of BMP target genes. Here, we show that the Ski oncoprotein can block BMP signaling and the expression of BMP-responsive genes in both Xenopus and mammalian cells by directly interacting with and repressing the activity of BMP-specific Smad complexes. This ability to antagonize BMP signaling results in neuralization by Ski in the Xenopus embryo and blocking of osteoblast differentiation of murine W-20-17 cells. Thus, Ski is able to repress the activity of all receptor-associated Smads and may regulate vertebrate development by modulating the signaling activity of transforming growth factor-beta family members.

Animals↗

PubMed2000

Experimental infection of nonenveloped DNA virus (TTV) in rhesus monkey.

Virus fragments homologous to TTV were detected previously from an enterically transmitted outbreak of non-A-E hepatitis [Luo et al., 1999]. To test the susceptibility of the Rhesus monkey to this virus and to establish its transmission routes, 6 Rhesus monkeys were inoculated, 3 orally and another 3 intravenously. The inoculum was prepared by extracting and filtering feces collected from a patient during the incubation period identified in the described outbreak. A second group of 3 monkeys was used for the passage study. The feces and blood samples were collected for detection of the virus by polymerase chain reaction (PCR). Four animals were subjected to liver biopsies and bile aspiration by open surgery for in situ virus detection. Viremia occurred in 4-7 days after intravenous and 7-10 days after oral inoculation. The virus was excreted in feces a few days after oral infection and simultaneously with viremia after intravenous inoculation. The virus was also detected in bile during the viremic phase. There was a prolonged carrier state with persistent viremia and virus excretion in feces for more than 6 months. Serum transaminase levels were not raised during the infection. The virus was present in both the cytoplasm and nuclei of hepatocytes, but no significant pathology was found. Therefore, the Rhesus monkey is susceptible to TT virus infection, but the virus seems nonpathogenic. Infection of the liver may be established either by oral or parenteral inoculation. The virus may be released from liver into the blood or via bile into feces, so it may be transmitted by both blood and fecal routes.

Alanine Transaminase↗

PubMed2000

Determination of low-level mercury based on a renewable-drops sensing technique.

The design and characteristics of a novel drop-based fluorescence-detection technique for the determination of mercury(II) are described. The method, using a flow injection technique, is based on the renewable-drops of 3,3',5,5'-tetramethylbenzidine(TMB), which are formed at the bottom tip of a silica capillary tube connected to the end of the flow system. An excitation beam from a high-pressure Hg lamp directly illuminates the drops, the fluorescence emission is conducted to a photodiode (PD) to convert the photocurrent into a voltage signal (mV). Optimum analytical conditions for Hg(II) assays have been established. In NaAc/HAc buffer at pH 3.09 this assay has a wide linear range for Hg(II) from 8.0 x 10(-8) to 2.0 x 10(-5) mol/L with a detection limit of 2.0 x 10(-8) mol/L. The use of renewable drops allowing a fresh reaction surface for each sample is of particular value to solving the problems of irreversible reactions. Besides its high sensitivity, the method permits a simple, fast, and inexpensive measurement with only micro-quantities of reagent consumption. The technique described provides a simple and sensitive way to fabricate sensors of feasible prospects and commercial advantages.

Benzidines↗

PubMed2000

[Influence of HBV/C mutation on HLA expression of host cells].

OBJECTIVE: To study the influence of HBV/C mutation on host cellular HLA expression. METHODS: HBV expression vectors carrying wild or variant HBV/C gene were constructed and transferred into HepG(2) cells. HBV/C gene expression on the host cells was identified. The expression of HLA-I and HLA-DR on the host cell membrane was detected. RESULTS: DNA segments similar with HBV/C gene size and HBcAg were detected by PCR and Western blot analysis, respectively. Almost all HepG(2) cells expressed HLA-I but not HLA-DR. The fluorescence intensity of HLA-I expression on host cells was different: HepG(2) was 57.8 and wild vector 54.3. The wild HBV/C gene declined significantly to 31.2. While V60, G87 and L97 increased to 43.0, 54.0 and 69.4, respectively. L97 was greatly increased with 11.6 higher than HepG(2). HLA-DR had no significant expression. CONCLUSION: Replication and expression of HBV/C gene can influence HLA-I expression on the host cells directly. Influence of variant gene on HLA-I expression is different from the wild gene. This might relate with the exacerbation of diseases resulting from HBV mutation.

Animals↗

PubMed2000

Hepatotropism of nonenveloped DNA virus in rhesus monkey infected by transfusion-transmitted virus.

OBJECTIVE: To study wether the nonenveloped DNA virus transmitted via blood transfusion is hepatotropic. METHODS: Total DNA was extracted from tissues of 5 experimentally infected Rhesus monkeys. A dot hybridization was done with virus double DNA strand probe or single antisense strand probe. RESULTS: Both single- and double-strand probes were hybridized with DNA of the liver, spleen, stomach, small intestine and colon. The virus was conformed present in most of all the organs when double-strand probe was used. The positive was noted only in the liver and small intestine when single-strand antisense probe was used, which showed that in liver and small intestine might have replicative intermediates of the virus. CONCLUSION: It suggests that nonenveloped DNA virus replicate in the liver and small intestine, so it might be hepatotropic.

Animals↗

PubMed2000

Effects of huang qi wu wu decoction on plasma proteins in 70 cases of chronic pulmonary heart disease.

Simple immune agar diffusion test was used to assay the contents of 12 plasma proteins in 70 cases of chronic pulmonary heart disease treated by Huang Qi Wu Wu Decoction ([symbol: see text]), with the other 70 cases who were not given Huang Qi Wu Wu Decoction as the control group. The total clinical effective rate in the treatment group was 90.0%, while that in the control group was 75.7%, with a statistically significant difference between the two groups (P < 0.05). In the treatment group, the levels of prealbumin, transferrin and fibronectin elevated obviously after treatment, and the contents of C-reactive protein, ceruloplasmin, haptoglobin, alpha 1-antitrypsin and alpha 1-acid glycoprotein decreased markedly (P < 0.01). In the control group, only the levels of ceruloplasmin and C-reactive protein decreased significantly (P < 0.05). It is shown that Huang Qi Wu Wu Decoction may enhance the therapeutic effects for pulmonary heart disease, regulate the metabolism of plasma proteins, and improve the life quality of the patients.

Aged↗

PubMed2000

[Experimental infection of a novel nonenveloped DNA hepatitis virus in Rhesus monkey].

OBJECTIVE: To test the susceptibility of the Rhesus monkey to the TT virus and to establish its transmission route. METHODS: Rhesus monkeys were administered orally and intravenously with the inoculum that was prepared with feces collected from a patient at the incubation period. Passage study was done with monkey' s positive feces. The blood, bile and feces were tested with polymerase chain reaction (PCR), and the liver, the jejunum tissues with in situ hybridization. RESULTS: The viremia occurred 4-7 days after intravenous inoculation and 7-10 days after oral administration. The virus was also excreted in the feces in a few days after oral infection and simultaneously with viremia after intravenous inoculation. The virus was also detected in the bile during the viremic phase. There was a prolonged carrier state that the viremia and fecal virus excretion persisted for more than 6 months. No serum transaminase elevation was found during the infection. There were virus signals in hepatocytes in columnar epithelium and lamina propria cells of jejunum villi, but no significant pathology was demonstrated in both sites. CONCLUSIONS: The liver infection of Rhesus monkey was established hb either oral or parenteral virus Inoculation. The virus may be released from liver into blood and intestine vial the bile or just from the gut wall into feces, and hence it may be transmitted by both routes.

Animals↗

PubMed2000

[Determination of rufloxacin in human plasma by high performance liquid chromatography].

A high performance liquid chromatographic method has been developed for the determination of rufloxacin in human plasma. Rufloxacin was extracted from plasma with dichloromethane for three times. It was chromatographed on an Ultrasphere ODS column with Pefloxacin as internal standard with a mobile phase consisting of methanol-tetrabutylammonium bromide-triethanolamine (32:68:0.5, V/V) adjusted to pH 2.8 with orthophosphoric acid. The flow rate was 1.2 mL/min and the monitoring wavelength was 295 nm. The calibration curve was linear from 0.1 to 10 mg/L of plasma. The detection limit of rufloxacin was 0.05 mg/L for plasma and the recovery was (97.7 +/- 2.1)%. The intra-day RSD and inter-day RSD were 2.33% and 3.38% respectively. The method is simple, rapid, accurate and can be used to determine the rufloxacin concentration in plasma and for pharmacokinetic study.

Adult↗

PubMed1999

Negative feedback regulation of TGF-beta signaling by the SnoN oncoprotein.

Smad proteins mediate transforming growth factor-beta (TGF-beta) signaling to regulate cell growth and differentiation. The SnoN oncoprotein was found to interact with Smad2 and Smad4 and to repress their abilities to activate transcription through recruitment of the transcriptional corepressor N-CoR. Immediately after TGF-beta stimulation, SnoN is rapidly degraded by the nuclear accumulation of Smad3, allowing the activation of TGF-beta target genes. By 2 hours, TGF-beta induces a marked increase in SnoN expression, resulting in termination of Smad-mediated transactivation. Thus, SnoN maintains the repressed state of TGF-beta-responsive genes in the absence of ligand and participates in negative feedback regulation of TGF-beta signaling.

Cell Division↗

PubMed1999

[Hepatitis B virus core promoter mutations in patients with fulminant hepatitis].

OBJECTIVE: To detect hepatitis B virus core promoter (CP) mutations in patients with fulminant hepatitis. METHODS: Polymerase chain reaction amplified serum HBV DNA fragments were directly sequenced. RESULTS: There were 2-12 nucleotide substitutions in CP region in the 7 subacute fulminant hepatitis patients studied. An 11 bp nucleotides insertion was found in one patient. Mutations in CP were usually seen in the first and the second A T rich regions. The A to T mutation at nt 1,762 and G to A mutation at nt 1,764 were found in 4 cases, 3 of them were HBeAg negative. The third A T rich region was kept intact in all the 7 patients, so did the initial site of HBV replication (DR1) and the initial site of mRNA transcription (1,783/1784 or 1,790 +/- 1 for precore mRNA and 1818 for pregenome-C/P mRNA). CONCLUSION: CP mutations in patients with fulminant hepatitis are common, most of the CP variations occur in the first and the second A T rich regions, and these mutations may impede the transcription of precore mRNA and affect the expression of HBeAg.

Amino Acid Sequence↗

PubMed1999

The Ski oncoprotein interacts with the Smad proteins to repress TGFbeta signaling.

Smad proteins are critical signal transducers downstream of the receptors of the transforming growth factor-beta (TGFbeta) superfamily. On phosphorylation and activation by the active TGFbeta receptor complex, Smad2 and Smad3 form hetero-oligomers with Smad4 and translocate into the nucleus, where they interact with different cellular partners, bind to DNA, regulate transcription of various downstream response genes, and cross-talk with other signaling pathways. Here we show that a nuclear oncoprotein, Ski, can interact directly with Smad2, Smad3, and Smad4 on a TGFbeta-responsive promoter element and repress their abilities to activate transcription through recruitment of the nuclear transcriptional corepressor N-CoR and possibly its associated histone deacetylase complex. Overexpression of Ski in a TGFbeta-responsive cell line renders it resistant to TGFbeta-induced growth inhibition and defective in activation of JunB expression. This ability to overcome TGFbeta-induced growth arrest may be responsible for the transforming activity of Ski in human and avian cancer cells. Our studies suggest a new paradigm for inactivation of the Smad proteins by an oncoprotein through transcriptional repression.

Cell Line↗

PubMed1999

[Tolerance of HepG2 and HepG2.2.15 cell lines to different apoptotic stimuli].

OBJECTIVE: To elucidate the effect of HBV on hepatocyte apoptosis. METHODS: The HepG2 cells and the HBV transfected HepG2.2.15 cells were cultured with MIX or ActD or cultured in DMEM medium without serum, The apoptosis was examined with FCM. RESULTS: The apoptotic rates of HepG2.2.15 cells at 24 h and 48 h after MTX addition were 10.8% and 13.3%, at 24 h and 48 h after Act D addition were 16.8% and 37.7%, and at 4th and 6th day after serum withdrawal were 13.2% and 14.8%, respectively. While those of HepG2 cells were 12.6% and 65.3%, 44.5% and 89.7%, and 19.8% and 28.8%, correspondingly. CONCLUSION: HepG2.2.15 cell was tolerant to these apoptotic stimuli, and it might be inferred that HBV inhibits hepatocyte apoptosis.

Apoptosis↗

PubMed1999

Cooperative binding of Smad proteins to two adjacent DNA elements in the plasminogen activator inhibitor-1 promoter mediates transforming growth factor beta-induced smad-dependent transcriptional activation.

Transforming growth factor beta (TGFbeta) activates transcription of the plasminogen activator inhibitor type-1 (PAI-1) gene through a major TGFbeta-responsive region (-740 and -647) in the PAI-1 promoter. This process requires the Smad family of signaling molecules. Upon phosphorylation by the TGFbeta receptors, Smad2 and Smad3 homoligomerize and heteroligomerize with Smad4, translocate to the nucleus and activate transcription of TGFbeta responsive genes. Smad3 and Smad4 have been shown to bind to various sites in the PAI-1 promoter. To determine the number of Smad-binding sites within the 94-base pair major TGFbeta-responsive region and the mechanism of Smad-mediated transactivation, we systematically mapped the Smad-binding sites and show that Smad4 and Smad3 bind cooperatively to two adjacent DNA elements in this region. Both elements were required for TGFbeta-induced, Smad3- and Smad4-dependent activation of PAI-1 transcription. Contrary to previous reports, transactivation of the PAI-1 promoter was mediated by the amino- but not carboxyl-terminal domains of the Smads. Furthermore, oligomerization of Smad3 markedly enhanced its binding to the two binding sites. Finally, a Smad4 mutation identified in a human pancreatic carcinoma that inactivates Smad4 signaling abolished Smad4 DNA binding activity, hence preventing transactivation of TGFbeta-responsive genes. These results underscore the importance of the Smad4 DNA binding activity in controlling cell growth and carcinogenesis.

Base Sequence↗

PubMed1999

Kaposi's sarcoma-associated herpesvirus: a sexually transmissible infection?

We examined sexual behavior as a risk factor for Kaposi's sarcoma-associated herpesvirus (KSHV) infection and examined the relation between KSHV seropositivity and development of KS in cross-sectional and cohort studies of 130 homosexual men diagnosed with AIDS in Sydney, Australia during the period from 1991 to 1993. KSHV serology was measured using antibody tests to latency-associated nuclear antigen (LANA) and lytically expressed open reading frame (ORF) 65.2. In the cross-sectional analysis, 52% (68) of study subjects were KSHV-seropositive by either assay. KSHV-seropositive men were significantly more likely to be seropositive to both herpes simplex type 2 (odds ratio [OR] 3.0; 95% confidence interval [CI], 1.2-7.5 for LANA and OR 2.8; 95% CI, 1.3-6.0 for ORF 65) and hepatitis A virus (OR 2.2; 95% CI, 1.1-4.5 for ORF 65). KSHV-seropositive men reported nonsignificantly more casual sexual partners and were nonsignificantly more likely to report insertive oroanal contact with casual partners. These data suggest that KSHV might be sexually transmitted among homosexual men. Men were observed until October 1996 for development of KS. Those seropositive to either KSHV assay at baseline were more likely than the seronegative to develop KS during follow-up (rate ratio [RR] 4.4; 95% CI, 1.9-10.2). Of those seropositive for KSHV, 53% developed KS.

AIDS-Related Opportunistic Infections↗