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Biomedical subjects

Jun Han

Publications and source records attributed to Jun Han.

At least 19 recordsLinked to original sources
PubMed2025

In vivo expansion of gene-targeted hepatocytes through transient inhibition of an essential gene.

Homology-directed repair (HDR)-based genome editing is an approach that could permanently correct a broad range of genetic diseases. However, its utility is limited by inefficient and imprecise DNA repair mechanisms in terminally differentiated tissues. Here, we tested Repair Drive, a platform technology for selectively expanding HDR-corrected hepatocytes in adult mice in vivo. Repair Drive involves transient conditioning of the liver by knocking down an essential gene, fumarylacetoacetate hydrolase (Fah), and delivering an untargetable version of the essential gene in cis with a therapeutic transgene. We show that Repair Drive increased the percentage of correctly targeted hepatocytes in healthy wild-type mice up to 25%, which resulted in a fivefold increased expression of a therapeutic transgene, human factor IX (FIX). Repair Drive was well tolerated and did not induce toxicity or tumorigenesis during a 1-year follow-up. This approach may broaden the range of liver diseases that can be treated with somatic genome editing.

Animals↗
PubMed2007

Kushen flavonoids induce apoptosis in tumor cells by inhibition of NF-kappaB activation and multiple receptor tyrosine kinase activities.

In this report, the mechanism of the antitumor activities of Kushen flavonoids (KS-Fs) were explored. KS-Fs and kurarinone (Kur), a single flavonoid compound, were able to induce apoptosis of H460 and Eca-109 cells in vitro and H460 cells in vivo. The apoptosis inducing effect was enhanced in the presence of Taxol. In H460 xenograft mice treated with Kur, down-regulation of Bcl-2 and up-regulation of caspase 8 and caspase 3 in tumors were observed by immunohistochemical staining. In addition, KS-Fs and Kur were able to inhibit TNFalpha-induced NF-kappaB activation in 293 cells mediated by the decreased IkappaBalpha phosphorylation. Further the effects of KS-Fs and Kur on multiple receptor tyrosine kinase activities were explored. In cell-based assays, KS-Fs and Kur inhibited the EGF-induced EGF receptor phosphorylation in A431 cells and a constitutively activated Her-2 in MDA-MB-453s cells. In enzymatic assays, KS-Fs and Kur inhibited KDR, but not PDGF BR activities. In A431 xenograft mice treated with Kur, an inhibition of EGF receptor phosphorylation in tumors was observed. These results reveal a novel mechanism by which KS-Fs induces apoptosis in tumors by acting on multiple cellular targets including the inhibition of NF-kappaB activation and multiple receptor tyrosine kinase activities.

Animals↗
PubMed2007

Novel antitumor activities of Kushen flavonoids in vitro and in vivo.

Kushen (KS), the dried roots of Sophora flavescens Aiton, has a long history of use in traditional Chinese medicine to treat inflammatory diseases and cancer. Kushen alkaloids (KS-As) and Kushen flavonoids (KS-Fs) are the well characterized components in KS. KS-As have been considered biologically active and developed in China as anticancer drugs. In an effort to screen novel antitumor agents from botanicals, more potent antitumor activities were identified in KS-Fs than in KS-As. KS-Fs were able to inhibit the growth of a panel of tumor cell lines and enhanced the antitumor activities of Taxol in vitro. The antitumor activities of KS-Fs and Kur, a single KS-Fs compound, were demonstrated in murine and xenograft human tumor models. Further, it was shown that KS-Fs and Kur were able to enhance the effect of Taxol to inhibit the growth of H460 and Eca-109 xenograft tumors. In addition, peripheral blood cell counts were not significantly affected in normal mice treated with KS-Fs at 200 mg/kg/day for 2 weeks. These results suggest that KS-Fs may be developed as novel antitumor agents and that the currently marketed KS-As drugs in China may have missed the major antitumor activities in Kushen.

Animals↗
PubMed2007

Simulating the transformation of heavy metals during coal or sewage sludge combustion.

A mathematical model (FPM) is presented to predict the transformation of heavy metals in the downstream of combustor or incinerator. The model accounts for the transformation of heavy metals through the combined effect of condensation, nucleation, coagulation, external force and thermophoresis force. The calculation of heavy metals is embodied in the post-processor appended to Fluent soft. Before the simulation, velocity, temperature, PbCl2 concentration and other initial parameters are obtained by experiment. In addition, the transformation of PbCl2 is also experimentally studied. The comparison of experimental and predicted results indicate that the fine particle model (FPM) is valid for predicting the transformation of heavy metals in the downstream of incinerator or combustor.

Coal↗
PubMed2006

Complete genome analysis of RFLP 184 isolates of porcine reproductive and respiratory syndrome virus.

Two full-length genomes of recently emerged virulent isolates of porcine reproductive and respiratory syndrome virus (PRRSV) were sequenced and compared to other PRRSV strains. The results revealed that these two isolates (named MN184), of North American lineage, represented the shortest PRRSV genomes sequenced to date with a nucleotide length of 15019 bases. Genetic analysis demonstrated that the two isolates were not identical and shared approximately 87 and 59% nucleotide identity with prototype North American strain VR-2332 and European strain Lelystad, respectively. Three quite variable regions were identified, corresponding to putative nsp1beta, putative nsp2 and ORF5. Nsp2, the most variable region, shared only 66-70% amino acid similarity to other sequenced North American-like PRRSV nsp2 proteins. Further study revealed that the nsp2 protein of the MN184 isolates contained three discontinuous deletions when compared to strain VR-2332 nsp2 protein, with the sizes of 111, 1, and 19 amino acids corresponding to strain VR-2332 positions 324-434, 486 and 505-523, respectively. The results suggest that targeted manipulation of PRRSV through nsp2 modification by reverse genetics may yield promising vectors for vaccine development, as has been recently demonstrated [Han, J., Faaberg, K.S., Wang, Y., Liu, H., 2005. Non-structural protein 2 mutants of PRRSV strain VR-2332 infectious clone based on deletions seen in RFLP184 isolates are viable. In: PRRS International Symposium Proceedings, vol. 8, Saint Louis, MO].

Amino Acid Sequence↗
PubMed2006

Targeting radioimmunotherapy of hepatocellular carcinoma with iodine (131I) metuximab injection: clinical phase I/II trials.

PURPOSE: HAb18G/CD147 is a hepatocellular carcinoma (HCC)-associated antigen. We developed iodine (131I) metuximab injection (Licartin), a novel 131I-labeled HAb18G/CD147-specific monoclonal antibody Fab'2 fragment, and evaluated its safety, pharmacokinetics, and clinical efficacy on HCC in Phase I/II trials. METHODS AND MATERIALS: In a Phase I trial, 28 patients were randomly assigned to receive the injection in 9.25-, 18.5-, 27.75-, or 37-MBq/kg doses by hepatic artery infusion. In a multicenter Phase II trial, 106 patients received the injection (27.75 MBq/kg) on Day 1 of a 28-day cycle. Response rate and survival rate were the endpoints. RESULTS: No life-threatening toxic effects were found. The safe dosage was 27.75 MBq/kg. The blood clearance fitted a biphasic model, and its half-life was 90.56-63.93 h. In the Phase II trial, the injection was found to be targeted and concentrated to tumor tissues. Of the 73 patients completing two cycles, 6 (8.22%) had a partial response, 14 (19.18%) minor response, and 43 (58.90%) stable disease. The 21-month survival rate was 44.54%. The survival rate of progression-free patients was significantly higher than that of patients with progressive disease after either one or two cycles (p < 0.0001 or p = 0.0019). CONCLUSION: Iodine (131I) metuximab injection is safe and active for HCC patients.

Adolescent↗
PubMed2006

Cell autonomous requirement for Tgfbr2 in the disappearance of medial edge epithelium during palatal fusion.

Palatal fusion is a complex, multi-step developmental process; the consequence of failure in this process is cleft palate, one of the most common birth defects in humans. Previous studies have shown that regression of the medial edge epithelium (MEE) upon palatal fusion is required for this process, and TGF-beta signaling plays an important role in regulating palatal fusion. However, the fate of the MEE and the mechanisms underlying its disappearance are still unclear. By using the Cre/lox system, we are able to label the MEE genetically and to ablate Tgfbr2 specifically in the palatal epithelial cells. Our results indicate that epithelial-mesenchymal transformation does not occur in the regression of MEE cells. Ablation of Tgfbr2 in the palatal epithelial cells causes soft palate cleft, submucosal cleft and failure of the primary palate to fuse with the secondary palate. Whereas wild-type MEE cells disappear, the mutant MEE cells continue to proliferate and form cysts and epithelial bridges in the midline of the palate. Our study provides for the first time an animal model for soft palate cleft and submucous cleft. At the molecular level, Tgfb3 and Irf6 have similar expression patterns in the MEE. Mutations in IRF6 disrupt orofacial development and cause cleft palate in humans. We show here that Irf6 expression is downregulated in the MEE of the Tgfbr2 mutant. As a recent study shows that heterozygous mutations in TGFBR1 or TGFBR2 cause multiple human congenital malformations, including soft palate cleft, we propose that TGF-beta mediated Irf6 expression plays an important, cell-autonomous role in regulating the fate of MEE cells during palatogenesis in both mice and humans.

Animals↗
PubMed2006

Effect of increased hepatic platelet activating factor and its receptor portal hypertension in CCl4-induced liver cirrhosis.

AIM: To evaluate the changes in hepatic platelet activating factor (PAF) and its receptors and their effect on portal pressure of cirrhotic rats induced by CCl4. METHODS: A model of liver cirrhosis was replicated in rats by intra-peritoneal injection of CCl4 for 8 wk. We determined the effect of hepatic PAF and its receptor level on portal and arterial pressure by EIA, saturation binding and RT-PCR technique. RESULTS: Compared to control rats, cirrhotic rats had higher hepatic PAF levels and output as well as higher plasma PAF levels (P<0.01, P<0.01, P<0.05, respectively). Both hepatic PAF receptor mRNA levels and PAF binding were nearly 3-fold greater in cirrhotic rats (P<0.01). Portal injection of PAF (1 g/kg WT) increased the portal pressure by 22% and 33% in control and cirrhotic rats, respectively. In contrast, the arterial pressure was decreased in the both groups (54% in control rats and 42% in cirrhotic rats). Injection of the PAF antagonist BN52021 (5 mg/kg WT) decreased the portal pressure by 16% in cirrhotic rats but had no effect in the control rats. CONCLUSION: The upregulation of the PAF system contributes to hepatic hemodynamic and metabolic abnormalities in cirrhosis, and the increased release of PAF into the circulation has impacts on the systemic hemodynamics.

Animals↗
PubMed2006

Correlations and predictions of pKa values of fluorophenols and bromophenols using hydrogen-bonded complexes with ammonia.

Density functional theory calculations have been preformed on a series of the hydrogen-bonded fluorophenol-ammonia and bromophenol-ammonia complexes. Intermolecular and intramolecular properties, particularly those related to hydrogen bonding, have been carefully analyzed. Several properties, such as the bond length and stretching frequency of the hydroxyl group, the hydrogen bond length and binding energy, are shown to be highly correlated with each other and are linearly correlated with known experimental pKa values of the halogenated phenols. The linear correlations have been used to predict the pKa values of all fluorophenols and bromophenols in the series. The predicted pKa values are shown to be consistent from different molecular properties and are in good agreement with available experimental values. This study suggests that calculated molecular properties of hydrogen-bonded complexes allow the effective and systematic prediction of pKa values for a large range of organic acids using the established linear correlations.

Journal Article↗
PubMed2006

Study on interaction between microtubule associated protein tau and prion protein.

Microtubule-associated protein tau is considered to play roles in many neurodegenerative diseases including some transmissible spongiform encephalopathies. To address the possible molecular linkage of prion protein (PrP) and tau, a GST-fusion segment of human tau covering the three-repeat region and various PrP segments was used in the tests of GST pull-down and immunoprecipitation. We found tau protein interacted with various style prion proteins such as native prion protein (PrPc) or protease-resistant isoform (PrPSc). Co-localization signals of tau and PrP were found in the CHO cell tranfected with both PrP and tau gene. The domain of interaction with tau was located at N-terminal of PrP (residues 23 to 91). The evidence of molecular interactions between PrP and tau protein highlights a potential role of tau in the biological function of PrP and the pathogenesis of TSEs.

Animals↗
PubMed2006

Recombinant neural protein PrP can bind with both recombinant and native apolipoprotein E in vitro.

The most essential and crucial step during the pathogenesis of transmissible spongiform encephalopathy is the conformational change of cellular prion protein (PrP(C)) to pathologic isoform (PrP(Sc)). A lot of data revealed that caveolae-like domains (CLDs) in the cell surface were the probable place where the conversion of PrP proteins happened. Apolipoprotein E (ApoE) is an apolipoprotein which is considered to play an important role in the development of Alzheimer's disease and other neurodegenerative diseases by forming protein complex through binding to the receptor located in the clathrin-coated pits of the cell surface. In this study, a 914-bp cDNA sequence encoding human ApoE3 was amplified from neuroblastoma cell line SH-SY5Y. Three human ApoE isomers were expressed and purified from Escherichia coli. ApoE-specific antiserum was prepared by immunizing rabbits with the purified ApoE3. GST/His pull-down assay, immunoprecipitation and ELISA revealed that three full-length ApoE isomers interact with the recombinant full-length PrP protein in vitro. The regions corresponding to protein binding were mapped in the N-terminal segment of ApoE (amino acid 1-194) and the N-terminal of PrP (amino acid 23-90). Moreover, the recombinant PrP showed the ability to form a complex with the native ApoE from liver tissues. Our data provided direct evidence of molecular interaction between ApoE and PrP. It also supplied scientific clues for assessing the significance of CLDs on the surface of cellular membrane in the process of conformational conversion from PrP(C) to PrP(Sc) and probing into the pathogenesis of transmissible spongiform encephalopathy.

Apolipoproteins E↗
PubMed2006

MALDI tissue imaging of ocular lens alpha-crystallin.

PURPOSE: To apply MALDI (matrix-assisted laser desorption ionization) tissue imaging methods to obtaining a profile of the distribution of the lens alpha-crystallins and their modified forms in calf and mature bovine lenses. METHODS: Frozen bovine lenses were cut equatorially at -12 degrees C to -20 degrees C into 10- to 40-microm sections depending on lens age. Tissue sections were mounted onto MALDI sample plates by ethanol soft-landing to maintain tissue integrity. A two-layered matrix deposition method was used to improve mass spectral reproducibility across sections. Molecular images of the two subunits of alpha-crystallin and their modifications over approximately one-half of a single tissue section were reconstituted from mass spectral data sets acquired in 250-microm steps. Identification of protein truncation products and confirmation of phosphorylation distribution patterns were performed by reverse-phase liquid chromatography of soluble extracts from specific tissue regions followed by tandem mass spectrometry (LC/MS/MS). RESULTS: Distinct distribution patterns were observed for the two subunits of alpha-crystallin and their modified forms. alphaA-crystallin showed extensive truncation across whole sections, especially in the nuclei, whereas alphaB-crystallin was observed to be relatively stable. Both alphaA-crystallin and alphaB-crystallin displayed the highest level of phosphorylation in the middle cortex region, a finding confirmed by LC/MS/MS analysis of dissected regions. CONCLUSIONS: A new imaging technique has been successfully applied to molecularly characterize the spatial distribution of lens proteins and their modifications in lens sections. The different distributions of alpha-crystallin revealed in this study provide new leads in the investigation of underlying physiological significance of the modified forms of the two alpha-crystallin subunits.

Animals↗
PubMed2006

Establishment of cell free conversion system with biotin-labelled recombinant PrPsen expressed in E. coli.

OBJECTIVE: To report a protocol using biotin-labelled PrP protein in cell free conversion assay instead of isotope. METHODS: A hamster PrP protein (HaPrP) was expressed in E. coli and purified with HIS-tag affinity chromatograph. After being labelled with biotin, HaPrP was mixed with PrPSc preparation from scrapie strain 263K. RESULTS: Protease-resistant bands were detected after four-day incubation. CONCLUSION: The new conversion model provides a reliable, easily handling, and environment-friendly method for studies of prion and transmissible spongiform encephalopathies.

Animals↗
PubMed2006

Protein expression of human neuron-specific enolase and its antiserum preparation.

OBJECTIVE: To clone and express human neuron-specific enolase (HuNSE) protein and prepare NSE-specific antibody for prion disease diagnosis. METHODS: HuNSE gene was amplified by RT-PCR and subcloned into a HIS-tagged expression vector pQE30 after sequence verification. HIS-NSE fusion protein expression was obtained in E. coli M15 after IPTG induction followed by purification of the fusion protein by Ni-NTA affinity chromatography. Two male rabbits were immunized for 4 times with the purified protein, and the antiserum against NSE protein was collected and evaluated by enzyme-linked immunosorbent assay (ELISA), Western blotting and immunohistochemistry. RESULTS: SDS-PAGE assay yielded an approximately 22 kD HIS-NSE fusion protein. The prepared antiserum could recognize both recombinant NSE protein and native NSE protein extracted from the brain tissues of different mammalian species as shown by Western blotting and immunohistochemistry. CONCLUSION: High expression of HuNSE is obtained in E. coli and the prepared antiserum against HuNSE can be used potentially for diagnosis of prion-associated diseases and other nervous degeneration diseases.

Animals↗
PubMed2005

[Influence of platelet activating factor and its antagonist on portal hypertension associated with liver cirrhosis: an experiment with rats].

OBJECTIVE: To investigate the influence of platelet activating factor (PAF) and its antagonist BN52021 on portal hypertension associated with liver cirrhosis. METHODS: Ten SD rats were injected intraperitoneally with carbon tetrachloride to establish a liver cirrhosis model and 10 rats were injected with olive oil as controls. The concentrations of PAF in the blood and liver was examined by rapid (3)H-PAF scintillation proximity assay and the hepatic PAF binding capacity was examined by receptor saturation binding technique. The pressure of portal vein and pressure of femoral artery were measured by intubation method. BN52021 was infused into the portal vein to observe its influence on the blood pressure. RESULTS: The hepatic PAF levels of the cirrhotic rats was 4.0 ng/g +/- 0.4 ng/g, significantly higher than that of the control rats (2.7 ng/g +/- 0.5 ng/g, P < 0.01). The hepatic efflux PAF level of the cirrhotic rats was 6.3 ng/g +/- 0.6 ng/g, significantly higher than that of the control rats (3.4 ng/g +/- 0.6 ng/g, P < 0.01). The hepatic output PAF levels of the cirrhotic rats was 1.0 ng/g +/- 0.6 ng/g, significantly lower than that of the control rats (0.3 ng/g +/- 0.5 ng/g, P < 0.01). The maximum PAF binding capacity of the cirrhotic rats was 2.8 +/- 0.21 fmol/microg protein, significantly higher than that of the control rats (0.9 +/- 0.06 fmol/microg protein, P < 0.01). However, the receptor affinity was not significantly different between these 2 groups. The portal pressure of the cirrhotic rats was 12.2 mm Hg +/- 0.7 mm Hg, significantly higher than that of the control rats (5.3 mm Hg +/- 0.6 mm Hg, P < 0.01). The femoral arterial pressure of the cirrhotic rats was 82 mm Hg +/- 10 mm Hg, significantly lower than that of the control rats (114 mm Hg +/- 9 mm Hg, P < 0.01). Infusion of PAF via the portal vein increased the portal pressure from 12.1 mm Hg +/- 0.6 mm Hg with an increase of 32% (P < 0.01) in the cirrhotic rats, and from 7.7 mm Hg +/- 0.8 mm Hg with an increase of 23%. The PAF response of the cirrhotic rats was 4.1 mm Hg +/- 1.0 mm Hg (227%), significantly higher than that of the control rats (1.8 mm Hg +/- 0.3 mm Hg, P < 0.01). The femoral artery pressure decreased from 82 mm Hg +/- 10 mm Hg to 48 mm Hg +/- 4 mm Hg (P < 0.01) in the cirrhotic rats, and from 114 mm Hg +/- 9 mm Hg to 52 mm Hg +/- 4 mm Hg (P < 0.01). After portal infusion of BN52021 the portal pressure decreased from 14.6 mm Hg +/- 1.6 mm Hg to 12.3 mm Hg +/- 0.8 mm Hg (P < 0.05) with a decrease of 16%, however, did not significantly influenced the femoral arterial pressure in the cirrhotic rats, and did not significantly influenced the portal pressure and femoral arterial pressure in the control rats. CONCLUSION: The increased hepatic PAF synthesis in cirrhotic is the major source of elevated circulating PAF It upregulates the hepatic hemodynamics that contributes to portal hypertension. The increased portal pressure by endogenous PAF can be decreased to a certain extent by BN52021 which may be used in treatment of portal hypertension.

Animals↗
PubMed2005

Combined deficiencies of Msx1 and Msx2 cause impaired patterning and survival of the cranial neural crest.

The neural crest is a multipotent, migratory cell population that contributes to a variety of tissues and organs during vertebrate embryogenesis. Here, we focus on the function of Msx1 and Msx2, homeobox genes implicated in several disorders affecting craniofacial development in humans. We show that Msx1/2 mutants exhibit profound deficiencies in the development of structures derived from the cranial and cardiac neural crest. These include hypoplastic and mispatterned cranial ganglia, dysmorphogenesis of pharyngeal arch derivatives and abnormal organization of conotruncal structures in the developing heart. The expression of the neural crest markers Ap-2alpha, Sox10 and cadherin 6 (cdh6) in Msx1/2 mutants revealed an apparent retardation in the migration of subpopulations of preotic and postotic neural crest cells, and a disorganization of neural crest cells paralleling patterning defects in cranial nerves. In addition, normally distinct subpopulations of migrating crest underwent mixing. The expression of the hindbrain markers Krox20 and Epha4 was altered in Msx1/2 mutants, suggesting that defects in neural crest populations may result, in part, from defects in rhombomere identity. Msx1/2 mutants also exhibited increased Bmp4 expression in migratory cranial neural crest and pharyngeal arches. Finally, proliferation of neural crest-derived mesenchyme was unchanged, but the number of apoptotic cells was increased substantially in neural crest-derived cells that contribute to the cranial ganglia and the first pharyngeal arch. This increase in apoptosis may contribute to the mispatterning of the cranial ganglia and the hypoplasia of the first arch.

Animals↗