[Tissue tropism of novel nonenveloped DNA virus in experimentally infected rhesus monkey]

OBJECTIVE

To investigate the tissue tropism of transfusion transmitted virus (TTV), a novel nonenveloped DNA virus, in experimentally infected Rhesus monkey.

METHODS

Filtrate of feces of one patient with TTV infection was fed into the stomachs of ten Rhesus monkeys. Five (?) monkeys were killed during viremia and their tissues were collected to be examined for the presence of replicative virus DNA by in situ hybridization, dot blot hybridization with antisense probe and hybridization/nuclease protection assay.

RESULTS

The virus contents (density of electrophoretic band) in the liver, PBMC, and serum of three infected monkeys 50.1%, 31.0%, and 18.9% respectively; the relative proportion was 2.65;1.64;1.00. TTV was detected in liver, spleen, stomach, small intestine and its lymph nodes, PBMC, colon, and serum; however, viral plus-chain, a putative replicative intermediate, was found only in liver, spleen, small intestine, and lymphoid cells.

CONCLUSION

Transfusion transmitted virus is hepato-, spleno-, and lymphoid cell-tropic, and may has multiple routes of transmission.

[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.

TGF-beta induces assembly of a Smad2-Smurf2 ubiquitin ligase complex that targets SnoN for degradation

The receptor-regulated Smad proteins are essential intracellular mediators of signal transduction by the transforming growth factor-beta (TGF-beta) superfamily of growth factors and are also important as regulators of gene transcription. Here we describe a new role for TGF-beta-regulated Smad2 and Smad3 as components of a ubiquitin ligase complex. We show that in the presence of TGF-beta signalling, Smad2 interacts through its proline-rich PPXY motif with the tryptophan-rich WW domains of Smurf2, a recently identified E3 ubiquitin ligases. TGF-beta also induces the association of Smurf2 with the transcriptional co-repressor SnoN and we show that Smad2 can function to mediate this interaction. This allows Smurf2 HECT domain to target SnoN for ubiquitin-mediated degradation by the proteasome. Thus, stimulation by TGF-beta can induce the assembly of a Smad2-Smurf2 ubiquitin ligase complex that functions to target substrates for degradation.

[Establishment of two-dimensional gel electrophoretic protein map of human spermatozoa]

OBJECTIVE

To establish the method of 2-dimensional electrophoresis(2-DE) for proteins of human spermatozoa and to construct a protein map of human spermatozoa.

METHODS

The sperm pellet was prepared with simple Percoll layer protocol. We studied the effects of various sample preparation methods, loading quantities and isoelectric-focusing protocols on the quality of silver-stained 2-DE map, and constructed a primary protein map of human spermatozoa.

RESULT

Up to 703 protein spots were acquired with sample preparation Method I while only 194-210 spots with Method II. With immobilized pH gradients and sodium dodecyl sulfate-polyacrylamide gel electrophoresis(IPG-DALT) we could acquire over 700 spots while only 280-300 with isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis(ISO-DALT).

CONCLUSION

It is satisfactory to lyse sperm with sample preparation Method I and to separate sperm proteins by IPG-DALT for establishing 2-D map of human sperm.

[Analysis of eleven isolated transfusion transmitted virus genotype]

OBJECTIVE

To analyze transfusion transmitted virus (TTV) genotype in hepatitis patients and healthy people.

METHODS

DNA fragment of TTV was amplified by polymerase chain reaction with nested primers in eight patients with liver disease and three healthy persons. The nested PCR products were cloned and sequenced.

RESULTS

A TTV DNA sequence of 222 bp (primer sequence excluded) was compared among the 11 subjects. The similarity between N22 and WH1, WH2, WH3, GZ1, GZ2, GZ3, SD2, SD3 was 97.0%, 97.0%, 98.0%, 98.0%, 95.0%, 95.0%, 94.6% and 95.5%, respectively. The similarity between TXO11 and GZ4, SD1, XJ1 was 98.0%, 98.0% and 95.0%, respectively.

CONCLUSION

According to Okamoto's method, the eleven TTV clones are classified into two subtypes: genotype 1a and 1b.

Genetic mutations of precore region of hepatitis B virus in hepatitis B e antigen-negative patients with fulminant hepatitis B and translation of precore variants in vitro

OBJECTIVE

To detect mutations in precore region of hepatitis B virus of HBeAg negative- patients with fulminant hepatitis and to determine the effect of T1862 mutants on synthesis of precursor of hepatitis B e antigen.

METHODS

The entire precore and core region were amplified from sera of nine HBeAg negative-patients with fulminant hepatitis B by polymerase chain reaction (PCR). PCR products were cloned into plasmid pUC18, and sequencing for analysis of precore mutations. Precore and core sequence of T1862 variant were also cloned into expression plasmid pGEMT for in vitro transcription and translation study on synthesis and procession of e antigen.

RESULTS

Three variants, A1896, A1899 and T1862, whose nucleotide mutation led to amino acids substitutions, were detected in patients with fulminant hepatitis. T1862 variant didn't effect the synthesis of precursor of e antigen. Also there was no variant detected in precore region of hepatitis B virus in two patients.

CONCLUSIONS

The causes for negative of e antigen in fulminant hepatitis patients may be partially explained by precore mutation of A1896 and T1862, and the latter variant may effect the process of precursor of e antigen, rather than the synthesis of precursor protein.

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.

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.

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.

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.

[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.

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.

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.

[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.

[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.

[Establishment of a method for classification of HBV genome and it's application]

OBJECTIVE

By using the techniques of PCR and restriction fragment length polymorphism (RFLP), we established a classification method for HBV genome based on viral S gene of asymptomatic HBV carriers (AsC).

METHODS

By using this method we classified HBV DNA of AsC living in Guangzhou, Shenyang, Beijing and Chongqing.

RESULTS

Among the AsC of Guangzhou, genotype B was 32.8%, genotype C 42.7%, mixed genotypes B and C 23.0%, others 1.6%; among the AsC of Chongqing, genotype B was 35.0%, genotype C 40.0%, mixed genotypes B and C 25.0%; among the AsC of Beijing, genotype B was 25.0%, genotype C 50.0%, mixed genotypes B and C 25.0%; among the AsC of Shenyang, genotype B was 11.1%, genotype C 88.9%. The prevalent HBV strains in China are genotype C and genotype B, and genotype C is the main genotype in west China.

CONCLUSION

The established method for genotyping is simple and convenient. Using this method, we also classified HBV DNA of the patients with chronic hepatitis B and liver cirrhosis living in Guangzhou, and found that mixed genotypes B and C was in 50.0% of the patients detected, suggesting the mixed infection might lead to a severe damage of the liver tissue.

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.

T1762/A1764 variants of the basal core promoter of hepatitis B virus; serological and clinical correlations in Chinese patients

BACKGROUND

A double variant in the basal core promoter, converting nucleotide 1762 from A to T (T1762) and nucleotide 1764 from G to A (A[764), has been described in patients with chronic hepatitis B infection. Its prevalence and significance in Chinese chronic HBV carriers are unknown.

METHODS

We studied 177 Chinese patients with chronic HBV infection (chronic hepatitis/asymptomatic: 89/88; hepatitis B e antigen positive/negative: 84/93). The double variant was detected by mismatched polymerase chain reaction and restriction fragment length polymorphism analysis. The reliability of this method was verified by sequencing in 41 serum samples with 100% matching.

RESULTS

The double variant T1762/ A1764 was found in 52 of 89 patients with chronic hepatitis, but in only 6 of 59 asymptomatic carriers (p<0.001). The prevalence was significantly lower in hepatitis B e antigen positive patients (23/84) than in hepatitis B e antigen negative patients (35/64) (p<0.005). Precore variant, A1896 was detected in 40 individuals; 31 of them suffered from chronic hepatitis and 9 were asymptomatic (p<0.001). A combination of both variants T1762/A1764 and A1896 was seen in 3 of 59 asymptomatic and 22 of 89 patients with chronic hepatitis (p<0.005).

CONCLUSIONS

Mismatched polymerase chain reaction with restriction fragment length polymorphism provides a reliable, easy and fast method for detection of the presence of the T1762/A1764 variant. In Chinese chronic hepatitis B carriers, T1762/A1764 variant was associated with both active liver disease and hepatitis B e antigen negativity.

Expression of a glycosylphosphatidylinositol-linked Manduca sexta aminopeptidase N in insect cells

Aminopeptidase N (APN; EC 3.4.11.2) is an exopeptidase that is attached to cell membranes by a hydrophobic amino-terminal stalk in vertebrates or a glycosylphosphatidylinositol (GPI) anchor in insects. In this study, we report the cloning, expression, and characterization of an aminopeptidase N from Manduca sexta midgut. The full-length aminopeptidase N cDNA (APN1a) encodes a 995-amino-acid protein. The predicted amino acid sequence differs by 8 amino acids from M. sexta APN1. These different amino acids do not modify any putative glycosylation or glycosylphosphatidylinositol anchor sites. The full-length cDNA was cloned into an expression plasmid, pHSP-HR5, and transiently expressed in an insect cell line derived from Spodoptera frugiperda (Sf21 cells). Immunoblot analysis with anti-APN antiserum showed that APN1a expressed in Sf21 cells is the same size (120 kDa) as APN found in midgut brush border membranes. After treatment with phosphatidylinositol-specific phospholipase C (PIPLC), anti-cross-reacting determinant antibody specific for PIPLC cleavage products recognized the expressed 120-kDa APN1a, but not endogenous Sf21 proteins, indicating that APN1a has an intact glycosylphosphatidylinositol anchor. These results are evidence that Sf21 cells synthesize few, if any, endogenous GPI-linked proteins. Immunofluorescence staining showed that the expressed APN1a was located on the surface of Sf21 cells.

[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.

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.