Production and characterization of immortalized rat hepatocytes secreting hepatocyte growth factor/scatter factor

BACKGROUND/AIMS

Hepatocyte transplantation is a recently attractive field in the treatment of liver failure and enzyme-deficient diseases. However, procurement of sufficient quantities of hepatocytes is almost impossible. We attempted to create a hepatocyte cell line that could be used for hepatocyte transplantation.

METHODOLOGY

L2A2 is a conditionally immortalized rat hepatocyte cell line produced by transfection of temperature-sensitive simian virus T antigen to the hepatocytes in the Lewis rat. Hepatocyte Growth Factor/Scatter Factor (HGF/SF)-secreting L2A2 cells, designated as SF-21, was produced by transfecting human HGF/SF cDNA into L2A2 cells.

RESULTS

This cell line was able to produce HGF/SF at the rate of 5-10 ng/10(6) cells/24 hrs, and the recombinant HGF/SF was of the expected size and was functionally active in that it could scatter Madin-Darby canine kidney cells. The SF-21 cells grew faster than its parental cell clone, and survived and proliferated at 37 degrees C in vitro. Also, the SF-21 cells were able to survive and proliferate when transplanted into the spleen of syngeneic rat, and expressed glucose-6-phosphatase.

CONCLUSIONS

These HGF/SF-secreting hepatocytes can be used as a model system to test a feasibility of using genetically engineered hepatocyte cell line for hepatocyte transplantation in the rat.

Regulation of phospholipase C-beta 3 activity by Na+/H+ exchanger regulatory factor 2

Among the phospholipase C that catalyzes the hydrolysis of phosphatidylinositol 4,5-bisphosphate, four mammalian phospholipase C-beta (PLC-beta) isotypes (isotypes 1-4) are activated through G protein-coupled receptors (GPCRs). Although the regulation of the PLC-betas by GPCRs and heterotrimeric G proteins has been extensively studied, little is known about the molecular determinants that regulate their activity. The PLC-beta isozymes carry a putative PSD-95/Dlg/ZO-1 (PDZ) binding motif (X(S/T)X(V/L)COOH) at their carboxyl terminus, which is implicated in specific interactions with anchor proteins. Using the yeast two-hybrid system, we identified Na(+)/H(+) exchanger regulatory factor 2 (NHERF2) as a protein that interacted with a C-terminal heptapeptide of PLC-beta3. Immunoprecipitation studies revealed that NHERF2 interacts specifically with PLC-beta3, but not with other PLC-beta isotypes. Furthermore, PLC-beta3 interacted with NHERF2 rather than with other PDZ-containing proteins. This interaction required the COOH-terminal NTQL sequence of PLC-beta3 and the second PDZ domain of NHERF2. Interestingly, NHERF2 potentiated the PLC-beta activation by carbachol in COS7 and HeLa cells, while mutant NHERF2, lacking the second PDZ domain, had no such effect. Taken together, the data suggest that NHERF2 may act as a modulator underlying the process of PLC-beta3-mediated signaling.

Midface distraction osteogenesis in cleft patients: a case report

We present a case of midface distraction in a bilateral cleft lip and palate patient. The patient was a 10-year-old who underwent a high LeFort I osteotomy followed by placement of the Rigid External Distraction halo. Distraction was commenced on the fifth postoperative day at a rate of 1 to 1.5 mm per day until a total of 17 mm of maxillary advancement had been achieved. There were no complications and follow up was at 9 months post distraction. Results show that the patient had improved facial aesthetics and dental occlusion which was overcorrected to a Class III relationship. Velopharyngeal function was unaffected. Distraction osteogenesis of the midfacial skeleton in cleft patients offers the possibility to remodel not only the underlying bony skeleton but also all the soft tissues of the face and palate.

Augmentation of immune response by altered peptide ligands of the antigenic peptide in a human CD4+ T-cell clone reacting to TEL/AML1 fusion protein

The 12;21 chromosomal translocation occurs in leukemic cells from 20(30% of patients with B-lineage childhood acute lymphoblastic leukemia, the result being the TEL/AML1 fusion gene carrying a sequence different from TEL or AML1. Because the protein newly formed by TEL/ AML1 fusion is probably not tolerated by human immune system, the fusion region is a good candidate for tumor antigen expressed only in TEL/ AML1-positive leukemic cells. We established two human CD4+ alphabeta T-cell clones (T31.1 and Y41.2) reacting to the TEL/AML1 fusion region, from two unrelated healthy donors. In order to do this, we stimulated peripheral blood mononuclear cells with synthetic peptides corresponding to the TEL/ AML1 fusion region. Both T31.1 and Y41.2 proliferated in response to TEL/ AML1 fusion protein as well as to a peptide IGRIAECILGMNPSR, in the context of HLA-DP5 and DP17, respectively, and killed B lymphoblastoid cells pulsed with the peptide. Furthermore, these T-cell clones proliferated in response to several altered peptide ligands carrying a single residue substitution in the TEL/AML1 peptide, and some induced augmentation of proliferation and production of Th1-type cytokines. These superagonistic altered peptide ligands can be given consideration for anti-leukemic immunotherapy.

[The effect of age on the regional blood flow of neck of femur in normal Chinese]

This study aimed to assess the effect of age on the regional blood flow of neck of femur in normal Chinese. 133Xe washout method was adopted. The result showed that the femur regional blood flow of normal Chinese decreased slowly with the increase of their age. The relation between age and femur blood flow might be expressed as F = -0.042Y + 9.01(F refers to blood flow, Y refers to age). The average femur regional blood flow of normal Chinese was 7.37 +/- 0.62 ml.(100 g.min)-1 for 21-40 years old. The authors suggest this result can be considered to stand for regional femur blood flow of young healthy adults.

HLA-DP-associated susceptibility to the optico-spinal form of multiple sclerosis in the Japanese

We studied polymorphism of the HLA-DP gene in 46 patients with optico-spinal form (Asian type) multiple sclerosis (MS) showing recurrent opticomyelitis and 46 patients with Western type MS with disseminated central nervous system involvement. We previously reported a significant association between an HLA-DRB1 *1501-DRB5*0101 haplotype and susceptibility to Western type but not Asian type MS. In the present study, we found that the frequencies of DPA1 *0202 and DPB1 *0501 alleles were significantly increased in patients with Asian type MS, as compared with findings in 92 healthy control subjects (91.3% vs 65.2%, P(corr)<0.05 and 89.1% vs 63.0%, P(corr)<0.05 respectively), but not in Western type MS. Our data provide further evidence that Asian and Western type MS are distinct regarding the immunogenetic background.

[Alteration in regional blood flow in minipigs' femur under inadequate decompression studied by isotopes washout method]

We studied the alteration in regional blood flow in minipigs' femur under inadequate decompression after hyperbaric air exposure. The animals were placed in the hyperbaric chamber and exposed to the pressure of 0.5 MPa for 1.5 h, which was reduced to atmosphere at an ascent rate of 0.03-0.04 MPa/min. Regional blood flow in the femur was measured by the isotopes washout method of inhaling 133Xe. The radioactivity was monitored by a multifunctional blood flowmeter interfaced to a minicomputer. Before exposure, the values of average blood flow (F) of femur on the left and right were 15.4 +/- 1.8 and 16.9 +/- 2.0 ml/100 g.min respectively. The values of blood flow (f1) of hematopoietic marrow were 19.1 +/- 2.0 and 21.3 +/- 2.0 ml/100 g.min (n = 7). After inadequate decompression, F values were reduced to 10.3 +/- 1.8 and 11.1 +/- 1.6 ml/100 g.min and f1 values reduced to 13.9 +/- 1.4 and 13.8 +/- 1.0 ml/100 g.min (n = 7), which were obviously lower than those before exposure (P < 0.05). This experiment showed that significant reduction in blood flow in the femur region occurred under inadequate decompression after the exposure of minipigs hyperbaric environment, suggesting that ischemia is a causative factor of osteonecrosis.

Identification of genes affecting production of the adhesive holdfast of a marine caulobacter

Caulobacters are stalked bacteria that produce a structure termed a holdfast which enables firm attachment to surfaces. Tn5 insertion mutagenesis was used to identify genes affecting holdfast production or function in the marine strain MCS6. Twelve thousand Tn5 insertion mutants were screened for adhesion defects by an assay involving the attachment of cells to polystyrene microtiter dish wells. Among adhesion-defective mutants, those with multiple polar (pleiotropic) defects were excluded and the remainder were examined for the presence of holdfast. Forty-one mutants that produced no detectable holdfast or a significantly reduced amount were found. Southern blot and pulsed-field gel electrophoresis analyses indicated that 11 unique Tn5 insertions were clustered in three regions of the genome. In addition, 71 mutants that adhered poorly or not at all to polystyrene, yet still produced a holdfast, were found. Southern blot and pulsed-field gel electrophoresis analyses of 15 of these mutants showed eight unique Tn5 insertion sites clustered in two additional regions of the genome. An assay involving attachment to glass treated with siloxane chemicals (producing surfaces with varying degrees of hydrophobicity or hydrophilicity) was used to attempt characterization of this phenotype. Unexpectedly, no simple pattern of differences in binding between the mutants and wild-type caulobacters was found. In particular, no reduction in the ability of the mutants to bind to hydrophobic surfaces was noted. Complementation with cosmid clones was successful in nearly all cases and confirmed the designation of five genomic regions of holdfast-related genes. No detectable cross-hybridization was observed with several holdfast-related gene regions from a freshwater caulobacter, providing further evidence that the marine and freshwater caulobacters are genetically distinct.

The mammalian Na+/H+ exchanger gene family--initial structure/function studies

A gene family of mammalian Na+/H+ exchangers has been identified. Three isoforms have been cloned, sequenced, and stably expressed, and structure/function studies have been begun. Several of the isoforms are found in the epithelia, and one of them is epithelial specific.

[Feasibility of the new WHO Trachoma Grading System in China]

The New WHO Trachoma Grading System is found feasible in China by an epidemiological survey of trachoma using the two trachoma grading systems, the new WHO system and the Chinese conventional system, especially for large scale examination and treatment and for epidemiological survey. However, the New System regards the proportion of active trachoma amongst children under 10 years as the index of the scope and severity of the disease in a community, while the authors opine that the trachoma prevalence in teenagers, especially in middle school students, better reflects the situation of trachoma infection in a Chinese community.

Proton and sodium 23 magnetic resonance imaging of human ocular tissues. A model study

Clinical evaluation of uveal melanomas by magnetic resonance imaging (MRI) techniques depends on developing an understanding of the appearance of these tumors in magnetic resonance (MR) images. We have determined MR characteristics of uveal melanomas by proton (1H) and sodium 23 MRI of freshly enucleated human eyes at 1.5 tesla. The MR images were obtained using two-turn proton and 23Na surface coils, designed to both transmit and receive the radiofrequency signal. Proton MRI techniques included saturation recovery and spin echo; the gradient-recalled echo technique was used for 23Na MRI. Proton and 23Na MR images provide complementary information; contrast between intraocular tumors and vitreous, lens, or subretinal hemorrhage may be varied by using MR pulse sequences that emphasize tissues based on T1, T2, proton, or sodium density values. A combination of proton and 23Na MRI provides differentiation between normal ocular structures and intraocular tumors, as well as associated complications, such as retinal detachments and subretinal hemorrhages.