Real time TaqMan PCR detection and quantitation of HBV genotypes A-G with the use of an internal quantitation standard

BACKGROUND

Diagnostic assays for the accurate quantitation of hepatitis B virus (HBV) DNA levels from patients undergoing antiviral therapy are useful for monitoring and tailoring therapy. Such assays should give accurate results with all HBV genotypes, including a seventh genotype of hepatitis B virus, genotype G, that has recently been identified in specimens from HBV-positive patients in the United States and Europe.

OBJECTIVES

To characterize the performance characteristics of a quantitative real time TaqMan PCR assay, the High Pure System Viral Nucleic Acid/COBAS TaqMan HBV Test, for the detection and quantitation of HBV genotypes A-G from patient plasma and serum. This test was evaluated for limit of detection, dynamic range, reproducibility, accuracy, and genotype inclusivity.

STUDY DESIGN

Primers and TaqMan probes specific for HBV and an internal quantitation standard (QS) were designed and tested using a set of plasmid DNAs representing various genotyped specimens. In addition, sensitivity, dynamic range, precision, and correlation with the COBAS AMPLICOR HBV MONITOR Test were evaluated using HBV dilution panels and patient specimens.

RESULTS AND CONCLUSIONS

A real time TaqMan assay was developed that detects and quantifies DNA from genotypes A-G equivalently. The assay has a limit of detection of <50 copies/ml with plasma and serum, a dynamic range up to 10(9) copies/ml, and good precision and accuracy. Titers obtained with this method without dilutions show good correlation across the dynamic range with titers obtained with the COBAS AMPLICOR HBV MONITOR Test.

A neuroprotective role of extracellular signal-regulated kinase in n-acetyl-o-methyldopamine-treated hippocampal neurons after exposure to in vitro and in vivo ischemia

In response to cerebral ischemia, neurons activate survival/repair pathways in addition to death cascades. Activation of cyclic AMP-response-element-binding protein (CREB) is linked to neuroprotection in experimental animal models of stroke. However, a role of the mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MAPK/ERK or MEK), an upstream kinase for CREB, and its relation to CREB phosphorylation in neuroprotection in cerebral ischemia has not been delineated. Previously, we reported that N-acetyl-O-methyldopamine (NAMDA) significantly protected CA1 neurons after transient forebrain ischemia [J Neurosci 19 (1999b) 87.8]. The current study is to investigate whether NAMDA-induced neuroprotection occurs via the activation of ERK and its downstream effector, CREB. NAMDA induced ERK1/2 and CREB phosphorylation with increased survival of HC2S2 hippocampal neurons subjected to oxygen-glucose deprivation. These effects were reversed by U0126, a MEK kinase inhibitor. Similarly, animals treated with NAMDA following ischemia showed increased ERK and CREB phosphorylation in the CA1 subregion of the hippocampus during early reperfusion period with increased number of surviving neurons examined 7 days following ischemia. The NAMDA-induced neuroprotection was abolished by U0126 administered shortly after reperfusion. The results showed that the ERK-CREB signaling pathway might be involved in NAMDA-induced neuroprotection following transient global ischemia and imply that the activation of the pathway in neurons may be an effective therapeutic strategy to treat stroke or other neurological syndromes.

Distribution of Elastomers and Silica in Polymer Blends Characterized by Raman Microimaging Technique

Raman microimaging technique was used to study the distribution of silica filler and elastomer domains in binary and ternary polymer blends containing cis1–4-polybutadiene BR; brominated poly(isobutylenecoparamethylstyrene) BIMS; Natural Rubber, NR; and/or Styrene-Butadiene Rubber, SBR. Contour maps depicting distribution of the elastomer phases and silica within each phase were obtained for 1 μm thick sections of blends having different compositions. All polymers were uniformly distributed throughout the blends. However, on a micrometer scale local fluctuations were clearly observed using Raman microimaging. The BR component is not as compatible with BIMS as are the other polymers based upon the presence of some single-phase BR domains exceeding 5 μm. Addition of the third polymer, either SBR or NR, to the blend improves the BR compatibility with BIMS since the BR domains are not as large. At low concentrations in a ternary blend, the NR phase appears concentrated near the BR domains, but in samples with higher NR concentrations, the natural rubber forms it own network and may also be found near the BIMS domains. The SBR phase was found to be near or within the BR domains. Silica was dispersed throughout the polymers in each blend, but tended to aggregate near the boundaries of the BIMS domains. Sometimes the silica was present within the BIMS domains, but did not locate within a BR domain.

[Induction of protective immunity in mice against Schistosoma japonicum by nucleic acid vaccine encoding the full-length paramyosin]

AIM

To investigate the immune efficacy of nucleic acid vaccination in mice against full-length paramyosin of Chinese Schistosoma japonicum.

METHODS

C57BL/6 and BALB/c mice were vaccinated intramuscularly with the nucleic acid vaccine (pCMV-SjC97) encoding the full-length gene of paramyosin of Chinese S. japonicum. Each group was immunized three times at weeks 0, 3 and 6. Mice vaccinated with pCMV blank vector served as negative control. Mice were challenged three weeks after final DNA boosting by percutaneous infection with cercariae. Six weeks after infection the mice were perfused, worm burden and eggs in the livers, spleens and intestines were counted. Sera from vaccinated mice were collected from the tail vein at weeks 0, 3, 6 and 9, respectively.

RESULTS

C57BL/6 mice vaccinated with pCMV-SjC97 produced predominantly IgG2a and IgG2b; whereas in BALB/c mice, IgG1, IgG2a and IgG2b antibodies. Immunization with the pCMV-SjC97 in C57BL/6 mice could confer significant worm reduction rate (35.5%-41.4%, P < 0.05) and egg reduction rate (liver: 44.5%-59.6%, P < 0.05; spleen: 56.7%-82.4%, P < 0.05; intestines: 57.9%, P < 0.05), but not in BALB/c mice.

CONCLUSION

The nucleic acid vaccine, pCMV-SjC97, could induce protective immunity in C57BL/6 mice significantly.

[Cloning, sequencing and expression of the full-length gene encoding paramyosin of Schistosoma japonicum in vivo]

AIM

To clone and sequence the gene encoding paramyosin of S. japonicum (Chinese strain) and to study the expression of the DNA-based vaccine encoding the full-length paramyosin of S. japonicum in vivo.

METHODS

Total RNA was isolated from adult S. japonicum using TRIzol reagent. The full-length cDNA encoding paramyosin of S. japonicum was amplified by RT-PCR and cloned into pGEM-T vector and sequenced by the method of dideoxy-mediated chain-termination. The cDNA encoding paramyosin of S. japonicum was subcloned into the expressive plasmid vector pCDNA/AMP(pCMV-Sjc97), and the recombinants were identified by restriction enzyme digestion and sequencing. The immunofluorescence assay was used to study the expression of Sjc97 in vivo in mice.

RESULTS AND CONCLUSION

The 2.6 kb cDNA encoding the full-length paramyosin of Chinese S. japonicum has been successfully cloned and sequenced for the first time. The full-length sequence of paramyosin of S. japonicum was determined. Comparison of the nucleotide sequence and the deduced amino acid sequence of Sjc97 with that of S. japonicum paramyosin (Philippine strain) (Sjp97), S. japonicum paramyosin(Japanese strain) (Sjj97), S. mansoni (Sm97), B6 and Y6 clone (the partial cDNA encoding paramyosin of Chinese strain) showed that Sjc97 differed from Sjp97 by 16/2,601 nucleotide and 3/866 amino acid substitutions (99.4% on nt-level and 99.7% on aa-level in homology); from Sjj97 by 20/2,601 nucleotide and 2/866 amino acid substitutions (99.2% on nt-level and 99.8% on aa-level in homology); and from B6 by 11/1,329 nucleotide and 1/443 amino acid substitutions (99.0% on nt-level and 99.8% on aa-level in homology); from Y6 by 13/1,329 nucleotide and 1/443 amino acid substitutions (98.9% on nt-level and 99.8% on aa-level in homology); Sjc97 differed from the Sm97 by 2,235/2,601 nucleotide and 34/866 amino acid (91.0% on nt-level and 96.0% on aa-level in homology). The plasmid expression vector encoding the full-length paramyosin of Chinese S. japonicum has been successfully constructed. The pCMV-Sjc97 vaccine could express Sjc97 protein in vivo in mice after intramuscular immunization.

[Observation on the dynamics of specific anti-GST antibodies in rabbits immunized with recombinant 26 kDa GST of Schistosoma japonicum]

AIM

To investigate the dynamics of the anti-GST antibodies in rabbits immunized with recombinant 26 kDa GST of Schistosoma japonicum.

METHODS

The specific antibodies were detected weekly by GST-ELISA in rabbits vaccinated with purified recombinant 26 kDa GST antigen of S. japonicum plus FCA/IFCA; rabbits immunized with 0.85% saline plus FCA/IFCA served as control group.

RESULTS

The specific anti-GST antibodies began to increase at week 4 post-immunization, the mean OD value in rabbits vaccinated with recombinant GST could reach 1.03 +/- 0.46 (adjuvant control group only 0.42 +/- 0.04). The experiment was completed at week 65 post-immunization when the mean OD values for specific anti-GST antibody in immunized rabbits were 0.94 +/- 0.26(0.29 +/- 0.16 in the control group).

CONCLUSION

Strong anti-GST antibody responses could be induced in rabbits vaccinated with recombinant 26 kDa GST of S. japonicum.

[Studies on the features of protective immune response induced by recombinant Sjc26GST of Schistosoma japonicum]

AIM

To compare the differences in the protective immune response induced by reSjc26GST between C57BL/6 and BALB/c mice.

METHODS

Mice were immunized subcutaneously with reSjc26GST emulsified with Freund's adjuvant. The specific antibody isotypes elicited by reSjc26GST, in vitro lymphocyte proliferation and cytokine responses to reSjc26GST were examined.

RESULTS

The level of anti-reSjc26GST IgG was higher in immunized C57BL/6 mice than in BALB/c mice, and examination of the IgG subclasses demonstrated that reSjc26GST-immunized C57BL/6 mice resulted in predominantly IgG1 and IgG2a/IgG2b antibody responses, whereas in BALB/c mice, IgG1 antibody. Cytokine production assays revealed that the quantity of IFN-gamma and IL-2 and IL-5 released from the reSjc26GST-primed splenocytes were significantly higher in C57BL/6 mice than in BALB/c mice. These results showed that the immunization with reSjc26GST in C57BL/6 mice elicited a mixed immune reaction of Th1 and Th2 cell responses as demonstrated by the elevated levels of IgG1, IgG2a/IgG2b and IL-2, IFN-gamma, IL-5, whereas in BALB/c mice, reSjc26GST immunization elicited Th2 response as demonstrated by the elevated levels of IgG1, IL-2 and IFN-gamma.

CONCLUSION

Immunization with reSjc26GST could elicit higher humoral and cellular immune responses in C57BL/6 mice than in BALB/c mice.

[Differences in haemozoin production and pathogenicity between chloroquine-sensitive and chloroquine-resistant strains of Plasmodium berghei]

AIM

To better understand the differences in haemozoin formation and pathogenicity between chloroquine-sensitive(N) and chloroquine-resistant(RC) strains of Plasmodium berghei.

METHODS

IRC mice were grouped as follows: group Xba I (Normal control, NC), group II (control treated with chloroquine alone, CC), group III (mice infected with N strain), group IV (mice infected with RC strain, RC) and group V (mice infected with RC strain and treated with chloroquine, RCC). Morphologic features of the parasites, parasitaemia, histological and ultrastructural changes of livers among the groups were compared.

RESULTS

Severe damages of the hepatic cells of the N group including increased lysosomes and swollen and fused mitochondria were detected. On the contrary, the prominent features in liver section of the RC group were inflammatory cell (notably mononuclear) infiltration and Kupffer cell activation. Numerous trophozoites and schizonts were sequestrated in hepatic sinusoids and less degeneration of parenchymal cells was found except for some swollen and vacuolated mitochondria. Internal food vacuoles containing haemozoin were found in the parasites of the N group, whereas external food vacuoles without haemozoin granules were arranged in foamy appearance within the parasitized cell of the RC group.

CONCLUSION

P. berghei RC strain may modify the mode of ingestion and degradation of hemoglobin in the parasites, resulting in impeding haemozoin formation. The difference in virulence between the N and RC strain of P. berghei is probably attributed to the significant differences in the induction of immune response of the host.

Display of positron emission tomography with Cadplan

Recent clinical experience at Peter MacCallum Cancer Institute (PMCI) with the use of unregistered Positron Emission Tomography (PET) images for radiotherapy target marking in the lung suggests that co-registered PET images would be invaluable. PMCI has three radiotherapy treatment planning systems but none of them currently is able to display or co-register PET images with Computed Tomography (CT) images. This paper details the approach taken to display co-registered PET images with the CADPLAN treatment planning system. CT Image files are normally transferred to Cadplan by DICOM transfer, but the Cadplan DICOM server will not receive (has no presentation context for) PET images. The fundamental design of the CADPLAN system envisages display of only a single image dataset, which must be a CT scan for planning reasons. The problem of data transfer is crudely solved by File Transfer Protocol (FTP) over the network. Fortunately the multislice format of the PET image files makes individual transfer manageable. A menu based C program running at the same time as Cadplan is invoked to sample the DICOM PET Image and create multiple Cadplan CART image format files that are co-registered with each existing transverse CT slice. With the Cadplan in contour mode, the program allows the co-registered PET images to be swapped in and out of the image section of the CART files promptly, while keeping the contour information. This allows radiotherapy target volumes to be marked using transverse PET emission images, and effectively circumvents the design constraints prohibiting the display of more than one image set. Contours can be over-laid for review on reconstructed sagittal or coronal views of CT or PET images constructed using the standard Cadplan tools. Co-registration is facilitated by identical positioning with the aid of lasers and FDG loaded fiducial markers on the PET scanner and CT couch. A polyurethane cast fixed with EFFILOCK is used to ensure identical patient orientation on the CT and PET couches. Since both imaging modalities are without significant geometric distortion the co-registration is then simply a translation. PET transmission images can be used for co-registration verification. The practical implementation of display of PET images with CADPLAN has enabled us to begin a trial of 10 patients, the results of which will be reported separately.

[Effects of pressure induced retinal ischemia on ERG in rabbit]

OBJECTIVE

To observe the effects of pressure induced retinal ischemia on electroretinogram(ERG) in rabbit.

METHODS

Retinal ischemia was induced in rabbits by increasing intraocular pressure at 30 mmHg, 60 mmHg, 90 mmHg, 120 mmHg for 45 minutes, and retinal function was monitored by eletroretinography.

RESULTS

There was no difference on ERG before or after the experiment both in 30 mmHg group and control one. In 60 mmHg pressure induced ischemia eyes, the amplitudes of the b-wave and OPs wave reduced significantly. Four hours after reperfusion, they were totally recovered. After an ischemic insult of 90 mmHg or 120 mmHg for 45 minutes, there was no response of ERG. Four hours later, the amplitudes of the b-wave and OPs wave were 66.912 +/- 20.157 and 16.423 +/- 3.965 the former, 38.852 +/- 23.438 and 8.610 +/- 12.090 the latter, respectively.

CONCLUSION

These results suggest that higher intraocular pressure causes more severe retina ischemic damage, and less recovery ability.

[The value of color Doppler imaging ultrasound in diagnosis of orbital diseases]

OBJECTIVE

To study the useful value of color Doppler imaging (CDI) ultrasound in the diagnosis and differential diagnosis of orbital diseases.

METHODS

By using the technique of CDI ultrasound, 288 cases with orbital diseases were examined to show color Doppler flow imaging and pulsed wave Doppler (PWD) spectrum.

RESULTS

Among 288 cases of the orbital diseases, 38 cases of malignant tumors and 23 cases inflammatory pseudotumors showed the signals of blood flow. From CDI ultrasound examination, there were 18 in 23 cases with benign mixed tumors of the lacrimal gland showing artery blood flow and 22 in 28 cases with neurilemoma showing signals of blood flow. No blood flow was obtained in 62 among 74 cases with cavernous hemangioma, in 16 cases of dermoid cysts or epidermoid cysts and 1 case of lipoma. From CDI, rich blood flow was seen in 4 and scarce in 3 cases with meningioma, and in 6 cases of optic nerve gliomas, there were 5 cases without any blood flow signals. Other 2 cases with benign hemangioendothelioma, 2 hemangiopericytoma and 1 neurofibroma showed rich or scarce blood flow signals. Among 29 cases of venous hemangiomas, 16 cases showed venous flow. Three cases with arteriovenous aneurysms showed artery blood flow in the CDI. Fifteen cases with varicosis exhibited a dynamic blood flow changes in the CDI. Six cases with infantile hemangioma, the decreased blood supply was shown in the CDI after treatment. In the thirteen cases with carotid artery cavernous sinus fistula, including 8 cases of internal carotid artery cavernous sinus fistula (CCF) and 5 dural cavernous sinus fistula (DCF), dilated superior ophthalmic vein (SOV) with arterialized blood flow was seen. In the mean time, PWD showed that the SOV of CCF had a higher velocity and a higher flow volume than that of DCF, while its resistance index was lower than that of the DCF. In 1 case with thrombophlebitis, its SOV showed dilated superior ophthalmic vein without blood flow.

CONCLUSIONS

CDI can provide the information of color blood flow in orbital diseases, especially the tumors with rich vascular tissue and orbital vascular diseases. It is important in the diagnosis and differential diagnosis of the orbital diseases in combination with B-mode ultrasound, CT or MRI.

GeneChip analysis after acute spinal cord injury in rat

Spinal cord injury (SCI) leads to induction and/or suppression of several genes, the interplay of which governs the neuronal death and subsequent loss of motor function. Using GeneChip, the present study analyzed changes in the mRNA abundance at 3 and 24 h after SCI in adult rats. SCI was induced at T9 level by the New York University impactor by dropping a 10-g weight from a height of 25 mm. Several transcription factors, immediate early genes, heat-shock proteins, pro-inflammatory genes were up-regulated by 3 h, and persisted at 24 h, after SCI. On the other hand, some neurotransmitter receptors and transporters, ion channels, kinases and structural proteins were down-regulated by 3 h, and persisted at 24 h, after SCI. Several genes that play a role in growth/differentiation, survival and neuroprotection were up-regulated at 24 h after SCI. Using real-time quantitative PCR, the changes observed by GeneChip were confirmed for seven up-regulated (interleukin-6, heat-shock protein-70, heme oxygenase-1, suppressor of cytokine signaling 2, suppressor of cytokine signaling 3, interferon regulatory factor-1, neuropeptide Y), two down-regulated (vesicular GABA transporter and cholecystokinin precursor) and two unchanged (Cu/Zn-superoxide dismutase and phosphatidyl inositol-3-kinase) genes. The present study shows that inflammation, neurotransmitter dysfunction, increased transcription, ionic imbalance and cytoskeletal damage starts as early as 3 h after SCI. In addition to these effects, 24 h after SCI the repair and regeneration process begins in an attempt to stabilize the injured spinal cord.

Synthesis and quantitative structure-activity relationships of fluorine-containing 4,4-dihydroxylmethyl-2-aryliminooxazo(thiazo)lidines as trehalase inhibitors

Five fluorine-containing 4,4-dihydroxylmethyl-2-aryliminooxazolidines and five 4,4-dihydroxylmethyl-2-aryliminothiazolidines were synthesized and evaluated for their inhibitory activity against trehalase in vitro. All these compounds were very readily synthesized compared with the natural trehalase inhibitors. They had moderate inhibitory activity toward trehalase, and showed larvicidal activity and inhibition action to insect flight. The steric parameters and semiempirical quantum parameters of these compounds were acquired by using the molecular modeling method and the PM3-SCF-MO method, respectively. A quantitative structure-activity relationship between half-inhibitory concentrations toward trehalase and the above parameters was established.

Syntheses and activities as trehalase inhibitors of N-arylglycosylamines derived from fluorinated anilines

Twelve N-arylglycosylamines were prepared in a one-pot reaction by treatment of D-glucose, D-galactose, D-mannose or D-xylose with fluorinated anilines in the presence of small amount of hydrochloric acid. The inhibitory activity against porcine trehalase and the fungicidal activity of the title compounds toward Rhizoctonia solani have been tested.

[Study on different responses of rats' small intestine mucous membrane and bladder transitional epithelium in the same carcinogenic urine environment]

OBJECTIVE

To preliminarily verify the tentative idea of replacement of bladder transitional epithelium with small intestine mucous membrane to prevent recurrence of carcinoma of bladder.

METHODS

A certain segment of small intestine was transplanted to the urinary bladder of the same body in 17 rats. Then N-butyl-N-(4-hydroxy-butyl) nitrosamine (BBN) was used to induce carcinoma of bladder. BBN was used to 11 control rats that did not undergo operation.

RESULTS

Bladder carcinoma failed to be found in the transplanted small intestine mucous membrane in all experimental rats except one. After stimulation of BBN, carcinoma of urinary bladder occurred in all rats' bladder transitional epithelium.

CONCLUSION

1) The carcinogenic substances in the urine of rats suffering from BBN-induced bladder carcinoma are carcinogenic only to bladder transitional epithelium and have no effect on small intestine epithelium. 2) Bladder transitional epithelium may be more sensitive to the urine carcinogenic substances and easier to be cancerized than small intestine epithelium. 3) The tentative idea of substitution of small intestine mucous membrane for bladder transitional epithelium to prevent the recurrence of bladder carcinoma is worth further studying.

[Projections of 5-HTergic fibers to the spinal phrenic nucleus and medullary phrenic premotor neurons in the cat]

Experiments were performed on 6 adult cats. Brainstem neurons that project to the phrenic nucleus were retrogradely labeled by microinjection of WGA-HRP into the spinal phrenic nucleus. The brainstem sections were double processed for HRP histochemical staining with TMB-DAB method and 5-HT immunohistochemical staining with anti-5-HT primary antibody and FITC conjugated immunofluorescent secondary antibody. HRP-5-HT double-labeled neurons were observed mainly in the nucleus raphe pallidus. A few double-labeled neurons were also observed in nucleus raphe obscurus and nucleus raphe magnus. 5-HT immunopositive terminal fibers were observed in the vicinity of HRP single-labeled neurons (phrenic premotor neurons) located in the nucleus ambiguus and ventrolateral solitary tract nucleus. The results indicate that the 5-HTergic neurons in the nucleus raphe pallidus send axonal projections to the phrenic nucleus, and that the brainstem phrenic premotor neurons also receive 5-HTergic axonal projections.

Afferent projection to the retrotrapezoid nucleus from respiratory related structures in the brainstem of rabbit--a retrograde CB-HRP tracing study

Experiments were performed on 10 adult rabbits. After microinjection of cholera toxin B-subunit conjugated horseradish peroxidase (CB-HRP) into the retrotrapezoid nucleus (RTN), retrogradely labeled neurons were mainly observed in the Kölliker-Fuse nucleus (KF), the medial parabrachial nucleus (PBM) and the lateral parabrachial nucleus (PBL). A few labeled neurons were also observed in the ventrolateral solitary tract nucleus, the ambiguus and retroambiguus nuclei, and the ventromedial area of retrofacial nucleus. Labeled terminal fibers were mainly observed in the retrofacial nucleus, the ambiguus and retroambiguus nuclei, the ventrolateral area of solitary tract nucleus, and the PBL-PBM-KF. The above results show that the RTN has axonal connections with the pontine and medullary respiratory related structures.

[Cloning and nucleotide sequencing of full length L segment cDNA of Hantavirus strain A9]

OBJECTIVE

Cloning and nucleotide sequencing of full length cDNA sequence of L segment of Hantavirus strain A9.

METHODS

The L segment cDNA of Hantavirus strain A9 was amplified by RT-PCR. PCR products were cloned and sequenced. Full length cDNA clone of the L segment was obtained by subcloning.

RESULTS

The L segment of strain A9 was 6 533 nucleotides in length and encoded a putative L polymerase that was 2 151 amino acids in length. Analysis of nucleotide and deduced amino acid sequences of the L segment of strain A9 showed a close relationship with the other Hantaviruses most notably the 76-118, Cl-1 and Cl-2 strains, with which they shared a 83.8% nucleotide identity. More distant similarity could also be seen with other Hantaviruses. Sequence comparison performed among the RNA-dependent RNA polymerases of 27 negative stranded RNA viruses revealed that the same existence of six conserved regions and several strictly conserved residues located at the deduced amino acid sequence of A9 L segment.

CONCLUSIONS

The nucleotide sequence of L segment of strain A9 was similar to other Hantavirus L segments. Deduced amino acid sequence of A9 L segment shares 6 conserved regions with other RNA virus RNA polymerase. The conserved residues in these polymerases and their possible functions in light of the available structural information have been discussed.