A M(r) 34,000 proinflammatory outer membrane protein (oipA) of Helicobacter pylori

The complete genome sequence revealed a family of 32 outer membrane proteins (OMPs) in Helicobacter pylori. We examined the effect of four OMPs (HP0638, HP0796, HP1501, and babA2) on the production of the proinflammatory cytokine, IL-8. Mutants of the four OMPs, as well as cagE and galE from H. pylori from the U.S. and Japan, were constructed by inserting a chloramphenicol-resistant cassette into the gene. Twenty-two pairs of parental and mutant H. pylori strains, as well as 160 clinical isolates (80 from Japanese and 80 from U.S.), were cocultured with gastric cancer cell lines. IL-8 production in the supernatant and adhesion was assayed by ELISA. HP0796, HP1501, babA2, and galE gene knockouts had no significant effect on IL-8 production. Knockout of the HP0638 gene in 81% of cag-positive strains reduced IL-8 production approximately 50%. The three cag-positive strains in which IL-8 levels were unchanged by HP0638 knockout had five or seven CT dinucleotide repeats in the 5' region, resulting in a frame shift and truncation. Strains with naturally inactive HP0638 gene were all from the U.S.; Japanese strains were always "on" and thus, on average, may be more virulent. Although cag-negative isolates produced a limited IL-8 response, cag-negative strains that contained a functional HP0638 gene produced more than 3-fold greater IL-8 than cag-negative nonfunctional HP0638 strains. We hypothesize that functional HP0638 gene may be an important virulence factor in relation to the risk of clinically significant outcomes of H. pylori infection. We denote HP0638 gene as outer inflammatory protein (oipA).

Expression of thioredoxin and glutaredoxin, redox-regulating proteins, in pancreatic cancer

Pancreatic cancer (pancreatic ductal carcinoma) is one of the most malignant solid tumors with poor prognosis. There is accumulating evidence that cellular reduction/oxidation (redox) status is deeply involved in the growth promotion and drug resistance of cancer cells. We therefore investigated the expression of redox-regulating proteins, such as thioredoxin (TRX) and glutaredoxin (GRX) in surgically resected pancreatic tissues and cis-diamminedichloroplatinum (CDDP)-resistant cells. Plasma levels of TRX were also measured in subjects with pancreatic diseases. Pancreatic ductal carcinoma tissues were immunohistochemically more positive for TRX (24/32 cases) and GRX (29/32 cases) than pancreatic cystadenocarcinoma or normal pancreas tissues. Plasma levels of TRX (mean +/- SD) measured by ELISA were significantly higher in patients with pancreatic ductal carcinoma (54.8 +/- 37.6 ng/ml, n = 60) than in healthy controls (24.4 +/- 12.9 ng/ml, n = 81). CDDP-resistant subclones of HeLa cells, HeLa-CP5 cells, had higher expression of TRX (1.5 fold) and GRX (1.6 fold) compared with parental HeLa cells by immunoblotting. These results indicate the possible association of TRX and GRX with malignant potential of pancreatic ductal carcinoma.

Cloning and characterization of the iutA gene which encodes ferric aerobactin receptor from marine Vibrio species

The iutA gene from marine Vibrio species SD004, which encoded a ferric aerobactin receptor for the uptake of iron(III), was cloned onto a multicopy plasmid, pUC 18, in Escherichia coli. Identification of the positive clone was achieved on the basis of its deferrization activity and was detected as a halo formation on the chrome azurol S (CAS)-containing selective plate. Nucleotide sequence analysis of the cloned DNA fragment revealed an open reading frame (ORF) which encoded a polypeptide of 706 amino acid residues, and the deduced molecular mass of this polypeptide was 77.906 kD. The amino acid sequence showed a 41% homology with that of the lutA protein from E. coli. The cloned gene was iutA, which encoded the ferric aerobactin receptor. Another incomplete ORF was found 100 bp upstream of the iutA gene, which was homologous (31 out of 49 amino acids) with the C-terminal region of the luc D protein of E. coli. It is suggested that aerobactin biosynthesis and the transport genes are located tandemly on the Vibrio chromosome and may form an aerobactin operon.

Effects of geranyl-geranyl-acetone administration before heat shock preconditioning for conferring tolerance against ischemia-reperfusion injury in rat livers

The effect of geranyl-geranyl-acetone (GGA) administration before heat shock preconditioning on heat shock protein (HSP) 72 induction and on the acquisition of tolerance against ischemia-reperfusion Injury was studied in rat livers. Male Wistar rats were divided into four groups: a control group (group C); a GGA group (group G); a simple heat shock group (group VH); and a heat shock with GGA premedication group (group GH). Five-, 10-, and 15-minute periods of heat shock preconditioning at 42 degrees C were performed in groups VH and GH. Subgroups were determined according to the period of heat shock exposure. After a 48-hour recovery, rats in groups C, VH5, VH15, and GH5 received a 30-minute period of hepatic ischemia. Induction of HSP72, survival rates, and changes in biochemical and histologic parameters were compared among the groups. Five-minute heat shock preconditioning was not enough to Induce HSP72. However, livers in group GH5 expressed approximately the same amount of HSP72 as those in group VH15. The expression of HSP72 in group GH15 was stronger than that found in group VH15. The degree and location of HSP72 expression were not different between groups GH5 and VH15. Seven-day survival was significantly better in groups GH5 (16/16) and VH15 (15/16) than in group C (8/16) or VH5 (9/16). The recovery of adenosine triphosphate in liver tissue was faster, and the release of liver-related enzymes during reperfusion was lower in groups GH5 and VH15 than in group C or VH5. Administration of GGA before heat shock preconditioning augmented the induction of HSP72 by decreasing the threshold for triggering the stress response.

Protective effect of a traditional Japanese medicine, Bu-zhong-yi-qi-tang (Japanese name: Hochu-ekki-to), on the restraint stress-induced susceptibility against Listeria monocytogenes

In this study, the effect of traditional Japanese (Chinese) medicine, Bu-zhong-yi-qi-tang (Japanese name: Hochu-ekki-to, HOT), on the restraint stress treatment (RST)-induced susceptibility against Listeria monocytogenes (L. monocytogenes) was examined. When RST was performed every day for 10 h from the day of infection, the bacterial numbers were increased at 3 and 5 days after the infection. Oral pretreatment with HOT for 7 days prevented such increases. Pretreatment with HOT prevented the suppression of antigen-specific IFN-gamma production by RST. HOT also prevented suppression of macrophage accumulation, including MHC-class II positives, in the peritoneal cavity and their bactericidal activity by RST. HOT suppressed the serum corticosterone level elevated by RST in infected mice. Taken together, the suppression of corticosterone using HOT participates in the prevention of suppressions of the bactericidal activity of macrophages, migration of macrophages and antigen-specific IFN-gamma production of Th1 cells by RST. Our findings suggest that HOT is a useful drug for patients suffering from stress disease to reduce the susceptibility to bacterial infection.

Conservation of Helicobacter pylori genotypes in different ethnic groups in Houston, Texas

This study was concerned with whether the Helicobacter pylori strains circulating among ethnic groups living in the same region differ. The polymerase chain reactions to genotype (cagA, vacA, and iceA) H. pylori isolates from healthy volunteers from 4 ethnic groups (black, n=35; white Hispanic, n=31; whites, n=30; Vietnamese, n=29) residing in Houston were examined. The Vietnamese volunteers had the "East Asian"-type cagA 3' repeat region structure, and the others had the "non-Asian" type. The most common genotypes were delineated as follows: blacks and Hispanics, cagA+, vacA s1b-m1, and iceA2; whites, cagA+, vacA s1a-m2, and iceA2; and Vietnamese, cagA+, vacA s1c-m2, and iceA2. Two Hispanic families were also examined. H. pylori isolates from the children and their mothers had the same genotype and were different from those associated with the children's fathers or brothers-in-law. Conservation of an H. pylori genotype within ethnic groups over the course of generations will prove useful for epidemiological study of the coevolution of humans and H. pylori.

Heat-shock preconditioning reduces oxidative protein denaturation and ameliorates liver injury by carbon tetrachloride in rats

Membrane lipids and cytosolic proteins are major targets of oxidative injury. This study examined the effect of heat-shock preconditioning associated with the induction of heat-shock protein 72 on liver injury, from the aspect of lipid peroxidation and protein denaturation after carbon tetrachloride (CCl4) administration in rats--one of the representative oxidative injuries. Male Wistar rats were divided into two groups, group HS (preconditioned by heat exposure) and group C (not preconditioned). Expression of HSP72 in the liver tissue was confirmed by Western blot analysis. After a 48-h recovery period, all rats were given CCl4 intragastrically. Liver damage was assessed by measuring serum liver-related enzyme levels and adenine nucleotide concentration in the liver tissue. Lipid peroxidation and protein denaturation were evaluated by measuring tiobarbituric acid reactive substances (TBARS) and by immunohistochemical staining of 4-hydroxy-2-nonenal(HNE)-modified proteins in the liver. Survival rates of the rats after CCl4 administration were also compared. Expression of HSP72 was clearly detected in group HS, but not in group C. Heat-shock preconditioning significantly improved the survival rate, suppressed the increase in liver-related enzyme levels and maintained adenosine triphosphate levels (P<0.01 each). HNE-modified proteins--denatured proteins by free radical attack--were significantly less stained in group HS than in group C (P<0.05). However, TBARS levels did not differ between groups. Because heat-shock preconditioning did not alter TBARS levels but reduced HNE-modified proteins in association with the expression of HSP72, it is suggested that HSP72 did not prevent lipid peroxidation but decreased the lipid peroxidation-induced denaturation of proteins. This seemed to be a mechanism of heat-shock preconditioning to ameliorate oxidative liver injury.

The augmentative effect of repeated heat shock preconditioning on the production of heat shock protein 72 and on ischemic tolerance in rat liver tissue

OBJECTIVE

Heat shock pretreatment induces heat shock protein (HSP)72 strongly in rat livers and provides the tolerance against subsequent ischemia-reperfusion injury. In this study, the effects of repeated heat shock pretreatment on the production of HSP72 in rat livers and on subsequent ischemic tolerance were investigated.

METHODS

Rats pretreated with repeated heat shock were compared with those that received a single heat shock pretreatment. The production of HSP72 was analysed using Western-blotting and densitometer. At 48 h after heat shock pretreatment, all rats were subjected to warm liver ischemia for 30 or 45 min and then reperfused. Survival rate of the animals and liver functions during reperfusion were analysed.

RESULTS

The production of HSP72 increased in the repeated heat shock group more than in the single heat shock group. Although there were no significant differences in animal survival or in liver functions after a 30-min ischemia between the single heat shock group and the repeated heat shock group, animal survival and liver functions after a 45-min ischemia were significantly better in the repeated heat shock group.

CONCLUSION

In rats, repetition of heat shock pretreatment augmented the production of HSP72 in liver tissue and protected the liver from ischemia-reperfusion injury.

[A case of Guillain-Barré syndrome (GBS) following human parvovirus B19 infection]

Human parvovirus B19 (HPV-B19) infection is recently known to produce variable clinical manifestations, but neurological disorder associated with this infection is uncommon. We reported a case of GBS associated with transient lupus-like status following HPV-B19 infection. This is the first report describing an adult case of GBS following HPV-B19 infection. A healthy female, aged 33, developed erythema infectiosum simultaneously with her 5-year-old daughter. On the same day, she noticed leg fatigue, which worsened in the following days. On the day 11th, she became unable to walk. Mild pancytopenia, liver injury, proteinuria, hypocomplementemia, and increased anti-nuclear antibody (ANA) were revealed at a hospital. Polymerase chain reaction detected HPV-B19 DNA in the serum. On the day 17th, she was admitted to our hospital because of moderate generalized weakness and mild sensory disturbance, which were symmetrical and distal-dominant. The deep tendon reflexes were absent. Analysis of cerebrospinal fluid showed albuminocytologic dissociation. Other laboratory data were normal except positive ANA. Enzyme-linked immunosorbent assay (ELISA) showed high titer of the serum IgM antibody to GM1 and GD1b. Serum anti HPV-B19 IgM and IgG tested by ELISA were also positive. She improved gradually after 2 courses of double filtrated plasma pheresis.

Comprehensive allelotype study of hepatocellular carcinoma: potential differences in pathways to hepatocellular carcinoma between hepatitis B virus-positive and -negative tumors

To examine the role of the loss of heterozygosity (LOH) in hepatitis-related carcinogenesis, we performed a genome-wide scan of LOH in 44 tumors of hepatocellular carcinoma (HCC) using 216 microsatellite markers throughout all human chromosomes. A high frequency of LOH (>30% of informative cases) was observed at 33 loci on chromosome arms 4q, 6q, 8p, 8q, 9p, 9q, 13q, 16p, 16q, 17p, and 19p. LOH on 19p has not yet been reported, and that appears to be a new candidate in the search for tumor suppressor genes. High rates of LOH are correlated with hepatitis B virus (HBV) positivity, poorly differentiated tumors, vascular invasion, and intrahepatic metastasis (P <.0001). LOH on 13q and 16q occurred more frequently in HBV(+) patients (P <.0001), and LOH on 6q occurred more frequently in virus-negative patients (P <.001). The frequency of LOH on 4q and 13q was significantly lower in well-differentiated tumors than in moderately and poorly differentiated tumors (P <.01). In contrast, LOH on 6q was frequently detected in well-differentiated tumors compared with other histological subclasses (P <.001). Our results suggest that LOH on 6q may play an important role in the early stage of hepatocarcinogenesis in virus-negative patients, but different mechanisms might underlie the initial step to carcinogenesis in HBV(+) patients. LOH on 13q and 16q may play an essential role in the progression of HBV(+) tumors. Further studies of fine deletion mapping on chromosomes 13q and 16q are required to define the genomic segments on which putative tumor suppressor genes responsible for HBV(+) tumors exist.

The protective role of Kupffer cells in humoral injury of xenoperfused rat livers

BACKGROUND

The role of Kupffer cells in a hepatic xenograft rejection is still unclear. We investigated the effect of blocking Kupffer cells on xenogeneic humoral injury using rat livers as the xenoperfusion models.

METHODS

Rat livers were perfused with fresh human blood after pretreatment either with normal saline (group 1; n = 8) or with gadolinium chloride (GdCl3) solution (group 2; n = 8). Tissue injury was evaluated by alanine aminotransferase release and histological examination. Tumor necrosis factor-alpha (TNF-alpha) production from rat livers was measured by enzyme-linked immunosorbent assay and also examined by immunohistochemistry. In addition, Kupffer cells were isolated after pretreatment either with normal saline or with GdCl3 solution and incubated with human serum. Localization of human C3 and IgM was examined by immunofluorescence.

RESULTS

Alanine aminotransferase release in group 2 was significantly higher than in group 1 (P = 0.015). Histological examination revealed more severe tissue injury in group 2. The mean TNF-alpha level was not significantly different between the two groups. In immunohistochemistry, TNF-alpha was positive primarily on vascular endothelial cells in both groups. Immunofluorescence of saline-treated Kupffer cells showed an uptake of human C3 in the cytoplasm, whereas no uptake was observed in GdCl3-treated cells. The uptake of human IgM did not differ between the two groups.

CONCLUSIONS

These results suggest that Kupffer cells have a protective role in preventing xenogeneic humoral injury. Their ability to absorb xenogeneic complements may contribute to this protective mechanism.

Differential expression of human spasmolytic polypeptide (trefoil factor family-2) in pancreatic carcinomas, ampullary carcinomas, and mucin-producing tumors of the pancreas

Human spasmolytic polypeptide (hSP) is a member of the trefoil peptide group, thought to be involved in mucin production and cell growth. It has been reported that hSP protein is expressed in digestive cancers but not in normal pancreas. The expression of hSP in pancreatic neoplasms has not been investigated in detail. The immunohistochemical expression of hSP protein was investigated in pancreatic carcinomas, ampullary carcinomas, mucin-producing tumors, serous cystadenomas and islet cell tumors of the pancreas. hSP was expressed in 23% of pancreatic duct cell carcinomas, and hSP protein was more frequently detected in cases of early-stage or histologically low-grade duct cell carcinomas than in cases of late-stage or histologically high-grade carcinomas. Patients with hSP protein expression showed a better prognosis than did those with negative hSP expression. hSP expression was detected in 92% of mucin-producing tumors, but was not detected in serous cystadenoma or islet cell tumors. Immunohistochemical hSP expression is related to differentiation and a better prognosis in pancreatic duct cell carcinomas. Furthermore, hSP protein is related to the pathogenesis and clinical characteristics of mucin-producing tumors of the pancreas.

Application of intravascular ultrasonography for intracaval tumor thrombectomies in adrenal metastasis from hepatocellular carcinoma: report of two cases

Intracaval tumor thrombus is one of the characteristic features of advanced hepatocellular carcinoma. To formulate an appropriate operative strategy for removing intracaval tumor thrombi, it is of great importance to accurately diagnose the location, any invasion into the wall of the vena cava, and the extent of intracaval tumor spread. Intravascular ultrasonographic imaging is a novel technology that enables the precise catheter-based assessment of the dimensions and morphology of the vascular structure and any lesions. We have applied this technology to the diagnosis of intracaval tumor thrombi originating from adrenal metastasis secondary to hepatocellular carcinomas. This modality was thus found to be useful in determining the best operative procedure for removing tumor thrombi in the inferior vena cava.

Novel drug delivery system using autologous fibrin glue--release properties of anti-cancer drugs

To clarify the release properties of anti-cancer drugs from fibrin glue, a study was performed using several anti-cancer drugs with remarkably different physical properties. Concentrated fibrinogen, fibronectin, and coagulation factor XIII were prepared from healthy human plasma according to the cryoprecipitate method. Fibrin glue containing anti-cancer drugs was prepared as follows; the cryoprecipitate was mixed with each anti-cancer drug and aprotinin, then thrombin was added. These glues were incubated in PBS containing plasminogen and urokinase at 37 degrees C for seven days, and the medium was then sampled several times after centrifugation. The drug concentration in each sample was measured using HPLC. Fibrin glue without aprotinin was quickly hemolyzed and disappeared after 2--4 h. That with aprotinin was only slightly hemolyzed and more than half remained after 7 days. Mitomycin C and fluorouracil were quickly released from the glue regardless of the presence or absence of aprotinin. However, enocitabine was gradually released from glue with aprotinin although quickly released from that without. The rate of release of each drug from the glue with aprotinin correlated well with its hydrophobicity. Thus, to establish a sustained release system using fibrin glue, one should use the more lipophilic anti-cancer drugs and a fibrinolytic enzyme inhibitor.

AXIN1 mutations in hepatocellular carcinomas, and growth suppression in cancer cells by virus-mediated transfer of AXIN1

The Wnt signaling pathway is essential for development and organogenesis. Wnt signaling stabilizes beta-catenin, which accumulates in the cytoplasm, binds to 1-cell factor (TCF; also known as lymphocyte enhancer-binding factor, LEF) and then upregulates downstream genes. Mutations in CTNNB1 (encoding beta-catenin) or APC (adenomatous polyposis coli) have been reported in human neoplasms including colon cancers and hepatocellular carcinomas (HCCs). Because HCC5 tend to show accumulation of beta-catenin more often than mutations in CTNNB1, we looked for mutations in AXIN1, encoding a key factor for Wnt signaling, in 6 HCC cell lines and 100 primary HCC5. Among the 4 cell lines and 87 HCC5 in which we did not detect CTNNB1 mutations, we identified AXIN1 mutations in 3 cell lines and 6 mutations in 5 of the primary HCCs. In cell lines containing mutations in either gene, we observed increased DNA binding of TCF associated with beta-catenin in nuclei. Adenovirus mediated gene transfer of wild-type AXINI induced apoptosis in hepatocellular and colorectal cancer cells that had accumulated beta-catenin as a consequence of either APC, CTNNB1 or AXIN1 mutation, suggesting that axin may be an effective therapeutic molecule for suppressing growth of hepatocellular and colorectal cancers.

Difference of the liver and kidney in glycine conjugation of ortho-substituted benzoic acids

The relative importance of the liver and kidney for glycine conjugation of ortho-substituted benzoic acids was investigated. Glycine conjugation of ortho-substituted benzoic acids was investigated in mouse liver and kidney mitochondria. The extent of glycine conjugation of benzoic acids with the halogen group decreased in the order F > Cl > Br > I. The conjugation of salicylic acid with glycine took place in only the kidney. 2-Methoxybenzoic acid exhibited no activity in the liver and kidney. The difference in glycine conjugation of ortho-substituted benzoic acids was observed between liver and kidney. The kidney was more active in glycine conjugation of ortho-substituted acids than the liver. In addition, the relationship between glycine conjugation and the chemical structure of ortho-substituted acids was examined in the liver and kidney. The size of the substituent had a far greater influence over glycine conjugation in the liver and kidney. Glycine conjugation was also dependent on the substituent electronegativity. It may be important that the substrates undergoing glycine conjugation contain a flat region coplanar to the carboxylate group.

Molecular epidemiology of Helicobacter pylori: separation of H. pylori from East Asian and non-Asian countries

The predominant H. pylori strain circulating among geographic locations differs with regard to the genomic structure. This study determined whether structural subtypes of the cagA 3' repeat region could be used to identify the population of origin of H. pylori isolates. We examined 600 cagA-positive H. pylori (Colombia, 100; USA, 100; France, 100; Canada, 20; Italy, 20; Korea, 100; Japan, 100; Hong Kong, 20; Taiwan, 20; Vietnam, 20). The cagA 3' region was amplified by PCR using primers specific to Japanese and Western 3' cagA gene sequences. PCR using Japanese cagA primers resulted in PCR products in 99-6 % of strains from East Asia but no non-Asian strains. Conversely, PCR using Western cagA primers resulted in amplicons in 100% of non-Asian strains, and only one from East Asia. cagA genotyping is useful for molecular epidemiological studies as strains can be completely separated by differences in the cagA 3' region.

Cytokine expression and production by purified Helicobacter pylori urease in human gastric epithelial cells

Cytokines have been proposed to play an important role in Helicobacter pylori-associated gastroduodenal diseases, but the exact mechanism of the cytokine induction remains unclear. H. pylori urease, a major component of the soluble proteins extracted from bacterial cells, is considered to be one of the virulence factors for the inflammation in the gastric mucosa that is produced in H. pylori infection. However, the response of human gastric epithelial cells to the stimulation of urease has not been investigated. In the present study, we used human gastric epithelial cells in a primary culture system and examined whether H. pylori urease stimulates the gastric epithelial cells to induce proinflammatory cytokines by reverse transcription-PCR and enzyme-linked immunosorbent assay. First, by using peripheral blood mononuclear cells (PBMC) and a gastric cancer cell line (MKN-45 cells), we confirmed the ability of purified H. pylori urease to induce the production of proinflammatory cytokines. Furthermore, we demonstrated that the human gastric epithelial cells produced interleukin-6 (IL-6) and tumor necrosis factor alpha, but not IL-8, following stimulation with purified urease. The patterns of cytokine induction differed among human PBMC, MKN-45 cells, and human gastric epithelial cells. These results suggest that the human gastric epithelial cells contribute to the induction of proinflammatory cytokines by the stimulation of H. pylori urease, indicating that the epithelial cells were involved in the mucosal inflammation that accompanied H. pylori infection.

Impact of hyperthermic preconditioning on postischemic hepatic microcirculatory disturbances in an isolated perfusion model of the rat liver

Sublethal hyperthermia and the following recovery from this heat exposure, referred to as hyperthermic preconditioning, elicits a transient state of tolerance to oxidative insults through an intracellular protective response: stress response. The impact of hyperthermic preconditioning on hepatic microcirculatory disturbance, which is one of the determinants of ischemia/reperfusion-induced injury of the liver, was investigated by using intravital fluorescence microscopy. Thirty minutes of ischemia and a subsequent 120 minutes of reperfusion was induced in an in situ isolated perfusion model of Sprague-Dawley rats. Heat stress was given by whole-body hyperthermia, and a subsequent recovery was allowed for 18 or 48 hours, respectively. Postischemic decrease in sinusoidal perfusion rate and sinusoidal diameter, leukocyte stagnation in sinusoids, and leukocyte adhesion in postsinusoidal venules were significantly attenuated in both hyperthermia-pretreated groups. A recovery of bile production, a reduction of liver enzyme release, and an attenuation of tissue edema and histological damage were also observed. A marked expression of heat shock protein (HSP) 70 and heme oxygenase (HO-1)/HSP32 was correlatively observed in the liver tissue coincident with the induction of these protective effects. Hyperthermic preconditioning provides a continuous long-term and constant inhibitory effect (up to 48 hours after heat exposure) on postischemic injury of the liver through the attenuation of microcirculatory disturbances. These beneficial effects might be associated with a concomitant increase in HSP70 and HO-1/HSP32 expression.

Morphologic studies of hepatocytes entrapped in hollow fibers of a bioartificial liver

A bioartificial liver cartridge was prepared by inoculating porcine hepatocytes into the inner space of hollow fibers of a hemodialyzer. The hepatocytes formed rod shaped cell aggregates during in vitro perfusion culture within 1 day. Morphologic examination was carried out on the aggregates by optical and electron microscopy. Each hepatocyte was in direct contact with adjacent cells and a bile canaliculus-like structure was occasionally seen between hepatocytes. High magnification observation showed that the canaliculus was separated from the remainder of the intercellular space by a tight junction. These facts suggest that the hepatocytes formed functionally associated cell aggregates with a compact morphology not unlike hepatocyte spheroids. These structures were well maintained for 7 days in culture, and then the amorphous area in the aggregates and the nonviable cell number increased with lengthening culture period. The bioartificial liver maintained the ability to metabolize lidocaine, ammonia, and galactose for 7 days and then deteriorated with time.

Comparison of PCR-restriction fragment length polymorphism analysis and PCR-direct sequencing methods for differentiating Helicobacter pylori ureB gene variants

A method utilizing PCR-restriction fragment length polymorphism (RFLP) in the Helicobacter pylori genes is widely used to differentiate strains. However, with this typing method only a single base change at a specific restriction site can be detected. In addition, it is unclear whether the nucleotide base change recognized by RFLP is related to a substitution of encoded amino acid. To examine the validity of the PCR-RFLP method, 933-bp PCR products were obtained from 41 different clinical H. pylori isolates and were digested with Sau3A restriction endonuclease. Furthermore, the nucleotides of the same region in the ureB gene were directly sequenced and compared. PCR-RFLP confirmed that there was genetic diversity within the ureB gene with three distinct types, one being well conserved and the other two being variations. However, the direct sequencing method revealed that there was no difference at the nucleotide level among these RFLP types. Base substitutions recognized by Sau3A occurred in the third-base position and did not change the encoded amino acid. In addition, many nucleotide mutations, which could not be recognized by Sau3A, were frequently found. These results suggest that the PCR-RFLP method provides for an easy typing scheme of isolates, but does not reveal the true extent of genetic diversity. It is proposed that careful observation is required for the interpretation of results when clinical isolates are differentiated.

Formation of 8-hydroxy-2'-deoxyguanosine and 4-hydroxy-2-nonenal-modified proteins in rat liver after ischemia-reperfusion: distinct localization of the two oxidatively modified products

Ischemia-reperfusion (IR) injury is an intractable process associated not only with therapeutic recanalization of vessels, but also with partial resection or transplantation of solid organs including liver. To develop methods for predicting the degree of hepatic IR injury and further to identify injured cells, we studied the formation of 8-hydroxy-2'-deoxy-guanosine (8-OHdG) and 4-hydroxy-2-nonenal (HNE)-modified proteins in the normothermic hepatic IR model of rats using immunohistochemistry, high-performance liquid chromatography (HPLC) determination and Western blot. The Pringle maneuver for either 15 or 30 min duration produced reversible or lethal damage, respectively. The levels of both products were significantly increased in proportion to ischemia duration 40 min after reperfusion, suggesting the involvement of hydroxyl radicals. Increased immunoreactivity of 8-OHdG was observed not only in the nuclei of hepatocytes but also in those of bile canalicular and endothelial cells. However, immunoreactivity of HNE-modified proteins was detected in the cytoplasm of hepatocytes, which was confirmed by Western blot, and in addition, in the nuclei of hepatocytes after severe injury. Thus, localization of the two oxidatively modified products was not identical. Our data suggest that these two products could be used for the assessment of hepatic IR injury in tissue, but that the biological significance of the two products might be different.