The X-ray structure of Aspergillus aculeatus polygalacturonase and a modeled structure of the polygalacturonase-octagalacturonate complex

Polygalacturonases hydrolyze the alpha-(1-4) glycosidic bonds of de-esterified pectate in the smooth region of the plant cell wall. Crystal structures of polygalacturonase from Aspergillus aculeatus were determined at pH 4.5 and 8.5 both to 2.0 A resolution. A. aculeatus polygalacturonase is a glycoprotein with one N and ten O-glycosylation sites and folds into a right-handed parallel beta-helix. The structures of the three independent molecules are essentially the same, showing no dependency on pH or crystal packing, and are very similar to that of Aspergillus niger polygalacturonase. However, the structures of the long T1 loop containing a catalytic tyrosine residue are significantly different in the two proteins. A three-dimensional model showing the substrate binding mode for a family 28 hydrolase was obtained by a combined approach of flexible docking, molecular dynamics simulations, and energy minimization. The octagalacturonate substrate was modeled as an unbent irregular helix with the -1 ring in a half-chair ((4)H(3)) form that approaches the transition state conformation. A comparative modeling of the three polygalacturonases with known structure shows that six subsites ranging from -4 to +2 are clearly defined but subsites -5 and +3 may or may not be shaped depending on the nearby amino acid residues. Both distal subsites are mostly exposed to the solvent region and have weak binding affinity even if they exist. The complex model provides a clear explanation for the functions, either in catalysis or in substrate binding, of all conserved amino acid residues in the polygalacturonase family of proteins. Modeling suggests that the role of the conserved Asn157 and Tyr270, which had previously been unidentified, may be in transition state stabilization. In A. niger polygalacturonase, the long T1 loop may have to undergo conformational change upon binding of the substrate to bring the tyrosine residue close to subsite -1.

Structure of aspergillopepsin I from Aspergillus phoenicis: variations of the S1'-S2 subsite in aspartic proteinases

The crystal structure of aspergillopepsin I (AP) from Aspergillus phoenicis has been determined at 2.18 A resolution and refined to R and R(free) factors of 21.5 and 26.0%, respectively. AP has the typical two beta-barrel domain structure of aspartic proteinases. The structures of the two independent molecules are partly different, exemplifying the flexible nature of the aspartic proteinase structure. Notably, the 'flap' in one molecule is closer, with a largest separation of 4.0 A, to the active site than in the other molecule. AP is most structurally homologous to penicillopepsin (PP) and then to endothiapepsin (EP), which share sequence identities of 68 and 56%, respectively. However, AP is similar to EP but differs from PP in the combined S1'-S2 subsite that is delineated by a flexible psi-loop in the C-terminal domain. The S1' and S2 subsites are well defined and small in AP, while there is no definite border between S1' and S2 and the open space for the S2 subsite is larger in PP. Comparison of the structures indicates that the two amino-acid residues equivalent to Leu295 and Leu297 of AP are the major determining factors in shaping the S1'-S2 subsite in the fungal aspartic proteinases.

Comparative studies on the GABA-transaminase immunoreactivity in rat and gerbil brains

Gamma-aminobutyric acid (GABA) is the most important inhibitory neurotransmitter in the central nervous system (CNS). Degradation of GABA in the CNS is catalyzed by the action of GABA transaminase (GABA-T). However, the neuroanatomical characteristics of GABA-T in the gerbil, which is a useful experimental animal in neuroscience, are still unknown. Therefore, we performed a comparative analysis of the distribution of GABA-T in rat and gerbil brains using immunohistochemistry. GABA-T immunoreactive neurons were observed in the regions which contained GABAergic neurons of both animals: corpus striatum; substantia nigra, pars reticulata; septal nucleus; and accumbens nucleus. GABA-T + neurons were restricted to layers III and V in the rat. Unlike the rat GABA-T + neurons were observed in layers II, III, and V of the gerbil cerebral cortex. These results suggest that the expression of GABA-T in the gerbil brain may be similar to that in the rat brain, except in the cerebral cortex.

Efficacy of use of colonoscopy in dextran sulfate sodium induced ulcerative colitis in rats: the evaluation of the effects of antioxidant by colonoscopy

The goals in developing animal models of inflammatory bowel disease (IBD) are to determine the underlying mechanisms and the action of currently available drugs and to evaluate the value of new therapeutic approaches. Because of the difficulty in determining the severity of colitis in living animals, it has been necessary to kill the experimental animals at varying stages in the studies. If colonoscopic evaluation or endoscopic biopsy is feasible in these experimental animals, continuous observations could be possible, thus avoiding the need to kill them. The aims of the current study were to assess the efficacy of endoscopic examination as a monitoring tool for the severity of colitis in rats and to the efficacy of DA-9601, an extract from Artemisia asiatica which has both antioxidative and cytoprotective actions, on dextran sulfate sodium induced ulcerative colitis in rats endoscopically. Sprague-Dawley rats received 4% DSS in drinking water for 5 consecutive days. Either DA-9601 or sulfasalazine was administered twice a day for 8 days, starting 3 days before DSS administration. After the colonoscopic evaluations on days 2, 4, and 5 after DSS administration the rats were also killed for gross and histopathological evaluations. Simultaneous measurements of malondialdehyde (MDA) and myeloperoxidase (MPO) activities were performed. There was a statistically significant correlation between the scores evaluated by the gross examination and colonoscopic scores, between the colonoscopic scores and the levels of MDA or mucosal MPO activities, and between colonoscopic scores and histopathological activity index. DA-9601 showed excellent improvement in gross lesion scores, decreased MDA amounts and MPO activities compared to sulfasalazine. In conclusion, the introduction of appropriate colonoscopic examination in animal models of IBD could avoid the sacrifice of experimental animals for interim evaluation and provide the valuable information on the course and efficacy of treatment. The potential usefulness of antioxidants in treating IBD is very promising based on the colonoscopic intervention of IBD.

The alteration of gamma-aminobutyric acid-transaminase expression in the gerbil hippocampus induced by seizure

It is well established that GABA degradation may play a key role in epileptogenesis. However, whether or not the expression of GABA-transaminase (GABA-T), which catalyzes GABA degradation and participates in the neuronal metabolism via GABA shunt, changes chronologically after on-set of seizure remains to be clarified. To identify the change of GABA-T expression in seizure, GABA-T expression in the gerbil hippocampus, associated with different sequelae of spontaneous seizures, was investigated. The distribution pattern of GABA-T immunoreactive neurons in the hippocampus between the seizure-resistant and pre-seizure group of seizure sensitive gerbils was similar. Interestingly, at 30 min postictal, the enhancement of GABA-T immunoreactivity in the perikarya was apparently observed. This contrasted with the decline in GABA-T immunoreactivity in the granular and pyramidal layer. At 12-24 h postictal, GABA-T immunoreactivity in the hilar neurons had declined significantly. However, the GABA-T immunoreactivity in the granular layer increased. These findings suggest that in the gerbil, the alteration in GABA-T expressions may play an important role in the self-recovery mechanism from seizure attack via both GABA degradation and regulation of neuronal metabolism.

Cassette mutagenesis of lysine 130 of human glutamate dehydrogenase. An essential residue in catalysis

It has been suggested that reactive lysine residue(s) may play an important role in the catalytic activities of glutamate dehydrogenase (GDH). There are, however, conflicting views as to whether the lysine residues are involved in Schiff's base formation with catalytic intermediates, stabilization of negatively charged groups or the carbonyl group of 2-oxoglutarate during catalysis, or some other function. We have expanded on these speculations by constructing a series of cassette mutations at Lys130, a residue that has been speculated to be responsible for the activity of GDH and the inactivation of GDH by pyridoxal 5'-phosphate (PLP). For these studies, a 1557-bp gene that encodes human GDH has been synthesized and inserted into Escherichia coli expression vectors. The mutant enzymes containing Glu, Gly, Met, Ser, or Tyr at position 130, as well as the wild-type human GDH encoded by the synthetic gene, were efficiently expressed as a soluble protein and are indistinguishable from that isolated from human and bovine tissues. Despite an approximately 400-fold decrease in the respective apparent Vmax of the Lys130 mutant enzymes, apparent Km values for NADH and 2-oxoglutarate were almost unchanged, suggesting the direct involvement of Lys130 in catalysis rather than in the binding of coenzyme or substrate. Unlike the wild-type GDH, the mutant enzymes were unable to interact with PLP, indicating that Lys130 plays an important role in PLP binding. The results with analogs of PLP suggest that the aldehyde moiety of PLP, but not the phosphate moiety, is required for efficient binding to GDH.

Efficacy of flubendazole and albendazole against Trichinella spiralis in mice

Efficacy of flubendazole and albendazole against Trichinella spiralis in mice were studied. ICR mice were experimentally infected with Trichinella spiralis and treated with either flubendazole (FBZ) or albendazole (ABZ) at four different stages of the parasite life-cycle. Oral administration of either FBZ or ABZ at 20 mg/kg and 50 mg/kg on 2 h, 8 h and 24 h (pre-adult stage) after infection eliminated 94.7-100% of adults as determined at necropsy on day 7 post infection (p.i.) and 96.9-100% of larvae on day 45 p.i. FBZ was more effective than ABZ against adult T. spiralis (at 2 to 6 days p.i.), when treated with a dosage of 20 mg/kg for 5 consecutive days (99.4% and 46.0% reduction with respect to the control group). Against migrating larval T. spiralis, FBZ was more effective than ABZ at 20 mg/kg for five consecutive days (on days 11-15 p.i.), and the reduction rate of recovered larvae were 99.6% (FBZ) and 80.8% (ABZ) respectively. FBZ was more effective against early encapsulated larval T. spiralis (at 21 to 25 days p.i.), than ABZ when both were given at 20 mg/kg for five consecutive days (99.8% and 45.4% reduction, respectively). In conclusion, flubendazole was more effective than albendazole against adult and parenteral stages of Trichinella spiralis in mice.

Emergence of vaccine-induced escape mutant of hepatitis B virus with multiple surface gene mutations in a Korean child

The S protein of hepatitis B virus is the principal component of virus envelope and the primary target of anti-HBs response. Mutants or variants that escape neutralization by anti-HBs have been selected during immunoprophylaxis of HBV after birth and liver transplantation. We investigated a case of a Korean child who was vaccinated at birth against hepatitis B and also given hepatitis B immunoglobulin, but nevertheless later became infected with the virus. Hepatitis B virus-specific deoxyribonucleic acid covering the region of genome encoding the predominant "a" determinant of hepatitis surface antigen was amplified using polymerase chain reaction, and the nucleotide sequence was determined. We present for the first time in Korea the independent emergence of an escape mutant with substitution of arginine for glycine at amino acid 145 and proline for glutamate at amino acid 120 in "a" determinant after immunization.

Oxidative damages are critical in pathogenesis of reflux esophagitis: implication of antioxidants in its treatment

BACKGROUND

The facts that the severity of reflux esophagitis cannot be accurately predicted on the basis of acid exposure and acid suppression treatment is not enough for the complete healing, suggested that other damaging factors might be involved in pathogenesis of reflux esophagitis.

AIMS

The present study was designed to evaluate the oxidative stress as the major pathogenic factor of reflux esophagitis and the importance of antioxidant in treatment of reflux esophagitis.

MATERIALS AND METHODS

Reflux esophagitis was induced by the insertion of small caliber ring (3 mm in diameter) into the duodenum 1 cm distal to the ligament of Treitz in rats.

RESULTS

DA-9601, a novel antioxidant substance, attenuated the gross esophagitis significantly compared to that treated with ranitidine, histamine-2 receptor antagonist (H2-RA), in a dose-dependent manner. Severe, hemorrhagic, and longitudinal ulcerations were developed in H2-RA pretreated group, whereas mildly scattered erosions were observed in antioxidant-pretreated group. Significantly increased amounts of malondialdehyde (MDA), increased NF-kappaB activation, and the mucosal depletion of reduced glutathione (GSH) were observed in the esophagus of reflux esophagitis. H2-RA treatment didn't affect the levels of GSH and MDA, whereas DA-9601 attenuated the decrement of the GSH levels and significantly decreased lipid peroxides in the esophagus. Antioxidants treatment showed significant reductions in the activation of NF-kappaB, inflammation-associated transcription factor, especially p50 component in accordance with significant higher levels of NF-kappaB repressor, IkappaBalpha expression.

CONCLUSION

Oxygen-derived free radicals seem to be one of the important mediators in generation of reflux esophagitis, which suggests that the combination of antioxidant and anti-secretory medications will be ideal and more beneficial in the prevention and treatment of reflux esophagitis than currently prescribed antisecretory treatment alone.

Brain succinic semialdehyde dehydrogenase: identification of reactive lysyl residues labeled with pyridoxal-5'-phosphate

An NAD+ dependent succinic semialdehyde dehydrogenase from bovine brain was inactivated by pyridoxal-5'- phosphate. Spectral evidence is presented to indicate that the inactivation proceeds through formation of a Schiff's base with amino groups of the enzyme. After NaBH(4) reduction of the pyridoxal-5'-phosphate inactivated enzyme, it was observed that 3.8 mol phosphopyridoxyl residues were incorporated/enzyme tetramer. The coenzyme, NAD+, protected the enzyme against inactivation by pyridoxal-5'-phosphate. The absorption spectrum of the reduced and dialyzed pyridoxal-5'-phosphate-inactivated enzyme showed a characteristic peak at 325 nm, which was absent in the spectrum of the native enzyme. The fluorescence spectrum of the pyridoxyl enzyme differs completely from that of the native enzyme. After tryptic digestion of the enzyme modified with pyridoxal-5'-phosphate followed by [3H]NaBH4 reduction, a radioactive peptide absorbing at 210 nm was isolated by reverse-phase HPLC. The sequences of the peptide containing the phosphopyridoxyllysine were clearly identical to sequences of other mammalian succinic semialdehyde dehydrogenase brain species including human. It is suggested that the catalytic function of succinic semialdehyde dehydrogenase is modulated by binding of pyridoxal-5'-phosphate to specific Lys(347) residue at or near the coenzyme-binding site of the protein.

Elevation of the gamma-aminobutyric acid transaminase expression in the gerbil CA1 area after ischemia-reperfusion damage

gamma-Aminobutyric acid-transaminase (GABA-T) plays an important role in the metabolism of GABA, particularly in the neurons or glial cells. The present study was undertaken to determine the alteration of GABA-T expression in the gerbil hippocampus after ischemia-reperfusion. In the sham, GABA-T(+) neurons were scattered in the hippocampus proper and dentate gyrus. The intensity of the GABA-T immunoreactivity had nearly disappeared in the interneurons at 12 h after ischemia. In contrast, 24 h post-ischemia the dramatic augmentation of GABA-T immunoreactivity in the pyramidal cells was observed in the CA1 area but not in the CA2 or CA3 areas. Forty-eight hours after ischemia-reperfusion, its immunoreactivity was preserved in the CA1 neurons. These results suggest that the over-expression of GABA-T in the CA1 area may be related to delayed neuronal death after ischemia-reperfusion insult.

Reversion from precore/core promoter mutants to wild-type hepatitis B virus during the course of lamivudine therapy

The effect of lamivudine administration on the evolution of precore/core promoter mutation is unknown. The aim of this study was to determine the changes of precore/core promoter sequences in chronic type B hepatitis patients treated with lamivudine. Serial sera were obtained from 11 patients before, at the beginning of, and during therapy. Serum samples were polymerase chain reaction-amplified, and nucleotide sequences of hepatitis B virus (HBV) were analyzed. At baseline, precore and core promoter mutations were found in 6 and 4 of 11 patients, respectively. A precore stop codon mutant was replaced by a wild-type virus in all 6 patients infected with precore mutant at a median treatment of 12 months (vs. before therapy; P =.011). Mutations in the core promoter appeared in only 1 of 10 patients (vs. before therapy; P =.021). However, precore and core promoter mutations appeared in 5 and 7 of 10 patients at a median treatment of 21 months, respectively. Acute exacerbation occurred after lamivudine withdrawal in 2 patients who had hepatitis B e antigen (HBeAg) loss or seroconversion. The serum remained HBeAg-negative throughout the study period, and each of 2 patients had precore wild-type virus during acute exacerbation. HBV mutants with core gene deletions are not eliminated completely during prolonged therapy in 2 patients in whom the HBV genomes had core gene deletions at baseline. In conclusion, lamivudine therapy resulted in reversion from precore/core promoter mutants to wild-type. However, mutations in the precore and core promoter region reappeared during prolonged therapy. HBeAg-negative wild-type precore hepatitis B virus could be selected after lamivudine withdrawal in patients who had HBeAg loss or seroconversion.

Shared epitope for monoclonal IR162 between Anisakis simplex larvae and Clonorchis sinensis and cross-reactivity between antigens

IR162 is a rat monoclonal IgE antibody (mAb). In the investigation of rat IgE production, the antigens recognized by IR162 (IR-Ags) were found to be expressed by a variety of helminthic parasites. By western blot analysis, IR162 detected bands in crude extracts of Anisakis simplex larvae, Clonorchis sinensis, Paragonimus westermani, plerocercoids of Spirometra mansoni, and Toxocara canis. Excretory-secretory material from A. simplex larvae also contained a protein recognized by IR162. IR162 mAb obtained from both Serotec and Zymed recognized identical bands of A. simplex larvae. Sandwich enzyme-linked immunosorbent assay analysis indicated that both IR-Ags of A. simplex larvae (IR-As) and C. sinensis (IR-Cs) were important antigens with respect to induction of specific IgG in human infections with these 2 organisms. Even though minimal cross-reaction between IR-As and IR-Cs was observed using sera from infected individuals, these results indicate that IR-Ags are found in the parasites examined, that IR-As and IR-Cs are the antigens that induce specific antibody in natural infection, and that the epitope that binds IR162 is shared by A. simplex larvae and C. sinensis.

Human brain GABA transaminase tissue distribution and molecular expression

Human brain gamma-aminobutyrate transaminase is differentially expressed in a tissue-specific manner. mRNA master dot-blot analysis for 50 different human tissues, including different brain regions and fetal tissues, provided a complete map of the tissue distribution. Genomic Southern analysis revealed that the gamma-aminobutyrate transaminase gene is a single copy, at least 15 kb in size. In addition, human brain gamma-aminobutyrate transaminase cDNA was expressed in Escherichia coli using a pGEX expression vector system. Catalytically active gamma-aminobutyrate transaminase was expressed in large quantities and the purified recombinant enzyme had kinetic parameters that were indistinguishable from those isolated from other mammalian brains. The human enzyme was inactivated by a well-known antiepileptic drug vigabatrin. Values of Ki and kinact were 1 mM and 0.35 min-1, respectively. Results from inactivation kinetics suggested that human gamma-aminobutyrate transaminase is more sensitive to the vigabatrin drug than the enzyme isolated from bovine brain.

Anticonvulsant compounds from the wood of Caesalpinia sappan L

80% Aqueous MeOH extracts from the wood of Caesalpinia sappan, which showed remarkable anticonvulsant activity, were fractionated using EtOAc, n-BuOH, and H2O. Among them, the EtOAc fraction significantly inhibited the activities of two GABA degradative enzymes, succinic semialdehyde dehydrogenase (SSADH) and succinic semialdehyde reductase (SSAR). Repeated column chromatographies for the fraction guided by activity test led to the isolation of the two active principal components. Their chemical structures were determined to be sappanchalcone and brazilin based on spectral data. The pure compounds, sappanchalcone (1) and brazilin (2), inactivated the SSAR activities in a dose dependent manner, whereas SSADH was inhibited partially by sappanchalcone and not by brazilin.

Replacement set mutagenesis of the four phosphate-binding arginine residues of thymidylate synthase

Arginines R23, R178, R179 and R218 in thymidylate synthase (TS, EC 2. 1.1.45) are hydrogen bond donors to the phosphate moiety of the substrate, dUMP. In order to investigate how these arginines contribute to enzyme function, we prepared complete replacement sets of mutants at each of the four sites in Lactobacillus casei TS. Mutations of R23 increase K:(m) for dUMP 2-20-fold, increase K:(m) for cofactor 8-40-fold and decrease k(cat) 9-20-fold, reflecting the direct role of the R23 side chain in binding and orienting the cofactor in ternary complexes of the enzyme. Mutations of R178 increase K:(m) for dUMP 40-2000-fold, increase K:(m) for cofactor 3-20-fold and do not significantly affect k(cat). These results are consistent with the fact that this residue is an integral part of the dUMP-binding wall and contributes to the orientation and ordering of several other dUMP binding residues. Kinetic parameters for all R179 mutations except R179P were not significantly different from wild-type values, reflecting the fact that this external arginine does not directly contact the cofactor or other ligand-binding residues. R218 is essential for the structure of the catalytic site and all mutations of this arginine except R218K were inactive.

Effects of solvent selection and fabrication method on the characteristics of biodegradable poly(lactide-co-glycolide) microspheres containing ovalbumin

To demonstrate the effect of formulation conditions on the controlled release of protein from poly(lactide-co-glycolide) (PLGA) microspheres for use as a parenteral drug carrier, ovalbumin (OVA) microspheres were prepared using the W/O/W multiple emulsion solvent evaporation and extraction method. Methylene chloride or ethyl acetate was applied as an organic phase and poly(vinyl alcohol) as a secondary emulsion stabilizer. Low loading efficiencies of less than 20% were observed and the in vitro release of OVA showed a burst effect in all batches of different microspheres, followed by a gradual release over the next 6 weeks. Formulation processes affected the size and morphology, drug content, and the controlled release of OVA from PLGA microspheres.

Randomized trial of N-butyl-2-cyanoacrylate compared with injection of hypertonic saline-epinephrine in the endoscopic treatment of bleeding peptic ulcers

BACKGROUND AND STUDY AIMS

Theoretically, the injection of cyanoacrylate may be effective for peptic ulcer bleeding, but randomized clinical trials are rare. The aim of this study was to compare the efficacy of N-butyl-2-cyanoacrylate (Histoacryl) and hypertonic saline-epinephrine (HSE) in the endoscopic treatment of major peptic ulcer hemorrhage.

PATIENTS AND METHODS

A total of 126 patients with major peptic ulcer hemorrhage and active bleeding or a nonbleeding visible vessel were randomly allocated to endoscopic injection with HSE (63 patients; group 1) or to injection with Histoacryl (63 patients; group 2). The two groups were well matched for age, sex, initial hemoglobin values, ulcer size and location, and bleeding stigmata.

RESULTS

Initial hemostasis was achieved in 58 cases (92.1%) in group 1 and in 60 cases (95.2%) in group 2 (P=0.717). Rebleeding rates were 16 of 58 in group 1 and seven of 60 in group 2 (P=0.051). There were no significant differences regarding the rates of permanent hemostasis (51 of 63 in group 1 vs. 57 of 63 in group 2, P=0.203), emergency surgery (seven of 58 in group 1 vs. three of 60 in group 2, P=0.200), or hospital mortality due to bleeding (0 in group 1 and 0 in group 2). With regard to the rebleeding rate, there was a significant difference between group 1 and group 2 in the subgroup with active arterial bleeding (11 of 26 in group 1 and four of 29 in group 2, P=0.039) but not in the subgroup with a nonbleeding visible vessel (five of 32 in group 1 and three of 31 in group 2, P=0.708). There were no statistically significant differences in hemostatic results between the two treatment groups in the subgroups with gastric ulcers or duodenal ulcers. Although no complications followed HSE therapy, arterial embolization with infarction occurred in two patients in the Histoacryl group, of whom one died.

CONCLUSIONS

Compared with HSE injection, Histoacryl injection showed no statistically significant differences in hemostatic results, except for decreasing the rebleeding rate in the patients with active arterial bleeding. However, the use of Histoacryl to control peptic ulcer bleeding should be reserved as a last resort before surgery, because of possible embolic complication.

Identification of three novel mutations and a high frequency of the Arg778Leu mutation in Korean patients with Wilson disease

Four mutations--R778L, A874V, L1083F, and 2304delC--in the copper-transporting enzyme, P-type ATPase (ATP7B), were identified in Korean Patients with Wilson disease. Arg778Leu, the most frequently reported mutation of this enzyme, was found in six of eight unrelated patients studied, an allele frequency of 37.5%, which is considerably higher than those in other Asian populations. The novel single nucleotide deletion, 2304delC, was found in one patient. Since a mutation at cDNA nucleotide 2302 (2302insC) had been previously described, this region of the ATP7B gene may be susceptible to gene rearrangements causing Wilson disease.

Overexpression, crystallization and preliminary X-ray crystallographic analysis of dihydrofolate reductase from bacteriophage T4

Dihydrofolate reductase (DHFR) from bacteriophage T4 is a homodimer consisting of 193-residue subunits. It has been crystallized in the presence of the cofactor (NADPH) and an inhibitor (aminopterin) at 296 K using sodium chloride as precipitant. The crystals are tetragonal, belonging to the space group P4(1)22 (or P4(3)22), with unit-cell parameters a = b = 61.14, c = 123.23 A under cryogenic conditions. The asymmetric unit contains a single subunit, with a corresponding V(m) of 2.65 A(3) Da(-1) and a solvent content of 53. 6%. Native data have been collected from a crystal to 1.9 A resolution using synchrotron X-rays.

Inflammatory pseudotumor of the urinary bladder in a child

The inflammatory pseudotumor of the urinary bladder is rare, especially in children. It is a benign proliferative lesion of the submucosal stroma easily mistaken for a sarcoma clinically, so it should be differentiated from a malignant neoplasm. We report the case of bladder inflammatory pseudotumor in a 7-year-old girl.

Life-threatening intraabdominal arterial embolization after histoacryl injection for bleeding gastric ulcer

N-butyl-cyanoacrylate (Histoacryl) injection has become the treatment of choice for acutely bleeding esophagogastric varices, and is the only effective option for endoscopic treatment of gastric varices. Recent reports confirm the ability of Histoacryl injection therapy to achieve immediate hemostasis in cases of gastric ulcer bleeding or Dieulafoy ulcer, where conventional endoscopic hemostatic treatment had failed. Although the overall safety record of Histoacryl injection has been relatively good, there have been scattered cases of serious complications. Here, we present two patients showing life-threatening intraabdominal arterial embolization after Histoacryl injection. They had chronic gastric ulcers with active arterial bleeding. In spite of attempts at hemostatic treatment, complete hemostasis was not achieved. We injected Histoacryl, diluted with Lipiodol, into bleeding gastric ulcers, resulting in successful hemostasis. Soon after the procedure, intraabdominal arterial embolization developed in both patients. One patient survived and the other died. Based on these experiences, we would like to warn gastrointestinal endoscopists to be alert to these fatal complications, and we propose that less diluted Histoacryl seems to be preferable in cases of bleeding peptic ulcers.

Mitochondrial ATPase 6 gene expression in unfertilized oocytes and cleavage-stage embryos

OBJECTIVE

To compare the level of mitochondrial ATPase 6 gene expression in unfertilized oocytes and cleavage-stage embryos.

DESIGN

Reverse transcription polymerase chain reaction was performed in unfertilized oocytes and cleavage-stage embryos derived from tripronucleate embryos to determine ATPase 6 gene expression.

SETTING

Department of Obstetrics and Gynecology, Human Genetics Laboratory, Infertility Medical Center of CHA General Hospital, College of Medicine, Pochon CHA University, Seoul, Korea.

PATIENT(S)

Oocytes were obtained from infertile couples undergoing in vitro fertilization.

INTERVENTION(S)

Unfertilized oocytes collected at 48 hours after retrieval and cleavage-stage embryos derived from tripronucleate embryos were prepared for evaluation of mitochondrial gene expression.

MAIN OUTCOME MEASURE(S)

Comparison of ATPase 6 gene expression by using single-cell reverse transcription polymerase chain reaction.

RESULT(S)

Expression of unfertilized oocytes decreased compared with early cleavage-stage embryos.

CONCLUSION(S)

Our findings of decreased ATPase 6 expression in unfertilized oocytes suggest that there may be a decrease in the mitochondrial functional capacity of oxidative phosphorylation.

Regulatory properties of glutamate dehydrogenase from Sulfolobus solfataricus

The purified glutamate dehydrogenase (GDH) from Sulfolobus solfataricus showed remarkable thermostability and retained 90-95% of the initial activity after incubation at -20 degrees C, 4 degrees C, and 25 degrees C for up to 6 months. Unlike mammalian GDHs, the activity of GDH from Sulfolobus solfataricus was not significantly affected by the presence of various allosteric effectors such as ADP, GTP, and leucine. Incubation of GDH with increasing concentration of o-phthalaldehyde resulted in a progressive decrease in enzyme activity, suggesting that the o-phthalaldehyde-modified lysine or cysteine is directly involved in catalysis. The inhibition was competitive with respect to both 2-oxoglutarate (Ki = 30 microM) and NADH (Ki = 100 microM), further supporting a possibility that the o-phthalaldehyde-modified residues may be directly involved at the catalytic site. The modification of GDH by the arginine-specific dicarbonyl reagent phenylglyoxal was also examined with the view that arginine residues might play a general role in the binding of coenzyme throughout the family of pyridine nucleotide-dependent dehydrogenases. The purified GDH was inactivated in a dose-dependent manner by phenylglyoxal. Either NADH or 2-oxoglutarate did not gave any protection against the inactivation caused by a phenylglyoxal. This result indicates that GDH saturated with NADH or 2-oxoglutarate is still open to attack by phenylglyoxal. Phenylglyoxal was an uncompetitive inhibitor (Ki = 5 microM) with respect to 2-oxoglutarate and a noncompetitive inhibitor (Ki = 6 microM) with respect to NADH. The above results suggests that the phenylglyoxal-modified arginine residues are not located at the catalytic site and the inactivation of GDH by phenylglyoxal might be due to a steric hindrance or a conformational change affected by the interaction of the enzyme with its inhibitor.

Functional characteristics of two BKCa channel variants differentially expressed in rat brain tissues

cDNAs encoding large-conductance Ca2+-activated K+ channel alpha-subunit (rSlo) were obtained from rat brain. From the DNA sequence of multiple rslo clones, we identified a specific sequence variation of 81 nucleotides, which is either absent from or present at the N-terminal region of a putative Ca2+-sensing domain of the channel. Transcripts containing such variations were detected in different ratios from several brain regions, and their functional significance was further examined. When heterologously expressed in Xenopus oocytes, both rSlo variants, named rSlo0 and rSlo27, generated Ca2+-activated and voltage-activated K+ currents characteristic of neuronal large-conductance Ca2+-activated K+ (BKCa) channels. Single-channel recordings of the two channels showed almost identical permeation characteristics and steady-state gating behavior. Noticeable differences between rSlo0 and rSlo27 were revealed when the macroscopic currents were measured at various voltages and intracellular Ca2+ concentrations. rSlo27 activated was more rapidly than rSlo0 in the presence of the same voltage stimulus, and the differences in these activation kinetics were dependent on the concentration of intracellular Ca2+. Despite their similar apparent affinities for Ca2+, rSlo0 and rSlo27 showed significant differences in their co-operative gating behavior. The Hill coefficient for intracellular Ca2+ was estimated to be about 3.7 for rSlo27 regardless of the membrane voltage, and that for rSlo0 was reduced from about 5 to 2 as the membrane voltage changed from 40 to 140 mV. As activation of BKCa channels is involved in rapid hyperpolarization of action potentials, the differential processing of rslo transcripts, and the generation of channels with different activation kinetics and Ca2+ cooperativity may be a mechanism for tuning the excitability of neurons in different brain regions.

Somatostatin and substance P induced in vivo by lipopolysaccharide and in peritoneal macrophages stimulated with lipopolysaccharide or interferon-gamma have differential effects on murine cytokine production

We have investigated whether lipopolysaccharide (LPS) induces substance P (SP) and somatostatin (SOM) in popliteal lymph nodes in vivo and whether macrophages are a source of SP and SOM in vitro. We have also investigated the effect of SP and SOM treatment on the production of cytokines. SP reached a maximum 3 days after injection of LPS (100 microg/footpad) and then declined. SOM expression after LPS injection reached a maximum at 5-7 days. Stimulation of thioglycolate-elicited peritoneal macrophages with LPS (20 microg/ml), recombinant interferon-gamma (rIFN-gamma, 100 U/ml), and LPS plus rIFN-gamma induced SOM and SP. Thioglycolate-elicited, unstimulated peritoneal macrophages also synthesized these peptides. SOM (10(-12)-10(-8) M) significantly inhibited IL-6 and IFN-gamma production, whereas SP at those concentrations enhanced cytokine production by activated lymphocytes and macrophages. These findings suggest that neuropeptides which originate from macrophages and nerve fibers act as immunomodulators to mediate changes in the pattern of cytokine production.

Hierarchical color image region segmentation for content-based image retrieval system

In this work, we propose a model of a content-based image retrieval system by using the new idea of combining a color segmentation with relationship trees and a corresponding tree-matching method. We retain the hierarchical relationship of the regions in an image during segmentation. Using the information of the relationships and features of the regions, we can represent the desired objects in images more accurately. In retrieval, we compare not only region features but also region relationships.

Identification of lysine residue involved in inactivation of brain glutamate dehydrogenase isoproteins by o-phthalaldehyde

Incubation of two types of glutamate dehydrogenase (GDH) isoproteins from bovine brain with o-phthalaldehyde resulted in a time-dependent loss of enzyme activity. The inactivation was partially prevented by preincubation of the GDH isoproteins with 2-oxoglutarate or NADH. Spectrophotometric studies indicated that the inactivation of GDH isoproteins with o-phthalaldehyde resulted in isoindole derivatives characterized by typical fluorescence emission spectra with a stoichiometry of one isoindole derivative per molecule of enzyme subunit. There were no differences between the two GDH isoproteins in sensitivities to inactivation by o-phthalaldehyde indicating that the microenvironmental structures of the GDH isoproteins are very similar to each other. Tryptic peptides of the isoproteins, modified with and without protection, identified a selective modification of one lysine as in the region containing the sequence L-Q-H-G-S-I-L-G-F-P-X-A-K for both GDH isoproteins. The symbol X indicates a position for which no phenylthiohydantoin-amino acid could be assigned. The missing residue, however, can be designated as an o-phthalaldehyde-labeled lysine since the sequences including the lysine residue in question have a complete identity with those of the other mammalian GDHs. Also, trypsin was unable to cleave the labeled peptide at this site. Both amino acid sequencing and compositional analysis identified Lys-306 as the site of o-phthalaldehyde binding within the brain GDH isoproteins.

Changes of splenocyte IFN-gamma mRNA synthesis in rats infected with Paragonimus westermani

Changes in the expression level of splenocyte IFN-gamma mRNA of Sprague-Dawley (SD) rats infected with Paragonimus westermani were analyzed by competitive reverse transcription-polymerase chain reaction (RT-PCR) followed by southern blot. The template RNA was extracted from the splenocytes of rats infected with 20 metacercariae of P. westermani. The products of competitive RT-PCR were subjected to southern blot and enhanced chemiluminescence (ECL), and analyzed with a densitometer. In comparison with that of uninfected control rat splenocytes (value of 1), the levels of mRNA expression of IFN-gamma had changed to 0.747 at 1 week post infection (PI), 0.00175 at 2 week PI, 0.0217 at 3 week PI, 0.194 at 4 week PI and then to 0.537 at 5 week PI. The level at 7 week PI had returned to 1.25, comparable with that of uninfected rats. These results show that, when infected with P. westermani, the levels of IFN-gamma mRNA of SD rat splenocytes were remarkably reduced by more than 500 times at 2 week PI and restored to normal level at 7 week PI.

Tc-99m MIBI SPECT is useful for noninvasively predicting the presence of MDR1 gene-encoded P-glycoprotein in patients with hepatocellular carcinoma

PURPOSE

Resistance to chemotherapeutic drugs continues to be one of the major unsolved problems in the treatment of cancer. Multidrug resistance is defined as the ability of cells exposed to a single drug to develop resistance to a broad range of structurally and functionally unrelated drugs as a result of enhanced outward transport of drugs mediated by P-glycoprotein that is encoded by multidrug resistance genes. Recent evidence has shown that Tc-99m MIBI is a suitable transport substrate for P-glycoprotein. A potential advantage of Tc-99m MIBI SPECT is its superiority to diagnose noninvasively the presence of P-glycoprotein overexpression in vivo. In this study, the authors determined the association of enhanced MIBI efflux in Tc-99m MIBI SPECT with overexpression of P-glycoprotein in hepatocellular carcinoma.

MATERIALS AND METHODS

Thirty-five patients with hepatocellular carcinoma were enrolled in the study. Tc-99m MIBI SPECT was performed 10 minutes after intravenous injection of 20 mCi Tc-99m MIBI. All patients had liver biopsy or surgery within 1 week of MIBI imaging. Immunohistochemical study of the biopsy or resected hepatocellular carcinoma specimens was performed using the avidin-biotin-peroxidase technique with monoclonal antibody JSB-1 directed against P-glycoprotein.

RESULTS

On Tc-99m MIBI SPECT, 30 of 35 (85.7%) patients with hepatocellular carcinoma had no Tc-99m MIBI uptake in tumor lesions, whereas five patients with hepatocellular carcinoma had Tc-99m MIBI uptake in tumor lesions. P-glycoprotein expression was observed in tumor tissues of all the patients without Tc-99m MIBI uptake, whereas among the five patients with Tc-99m MIBI uptake, no P-glycoprotein expression was seen in tumor lesions (P < 0.015).

CONCLUSION

Tc-99m MIBI SPECT is useful for noninvasively predicting the presence of MDR1 gene-encoded P-glycoprotein in patients with hepatocellular carcinoma.

Analysis of the precore and core promoter DNA sequence in liver tissues from patients with hepatocellular carcinoma

To investigate the role of mutant hepatitis B virus (HBV) in the development of hepatocellular carcinoma (HCC), 20 patients with HCC were studied for precore and core promoter mutations in tumorous and nontumorous tissues. The precore and core promoter region was amplified and analyzed by direct sequencing. Among the 20 tumorous and nontumorous tissues, precore mutant HBV was found in 12 (60%) and 18 (90%), respectively. Of the 12 tumorous tissues with precore mutant, nine tissues had a single mutation (1896) and one tissue had another single mutation (1899). The remaining two tissues had a double mutation (1896 and 1899). A single mutation (1896) and a single mutation (1899) were found in 11 and two of the 18 nontumorous tissues with precore mutant, respectively. Among 20 tumorous and nontumorous tissues, HBV with a C to T mutation at nucleotide (nt) 1846 was detected in six and eight, respectively, and was associated with the virus carrying a mutation (1896 or 1899) except in two tumorous tissues. Mutations at nt 1762 and 1764 in core promoter were observed in 16 (80%) tumorous tissues and 18 (90%) nontumorous tissues. Mutations in the precore and core promoter region were found frequently in nontumorous tissue and in tumorous tissue (18/20 and 12/20 in precore region, 18/20 and 16/20 in core promoter respectively). The high prevalence of precore and core promoter mutations in liver tissue from patients with HCC suggests that these mutations may contribute to the development of HCC.

Photoaffinity labeling of brain glutamate dehydrogenase isoproteins with an azido-ADP

The ADP binding site within two types of bovine brain glutamate dehydrogenase isoproteins (GDH I and GDH II) was identified using photoaffinity labeling with [alpha-32P]8-azidoadenosine 5'-diphosphate (8N3ADP). 8N3ADP, without photolysis, mimicked the activatory properties of ADP on GDH I and GDH II activities, although maximal activity with 8N3ADP was about 75% of maximal ADP-stimulated activity. Saturation of photoinsertion with [alpha-32P]8N3ADP occurred at around 40 approximately 50 microM photoprobe with apparent Kd values near 25 and 40 microM for GDH I and GDH II, respectively. Photoinsertion of [alpha-32P]8N3ADP was decreased best by ADP in comparison with other nucleotides. With the combination of immobilized aluminum affinity chromatography and reversed-phase high performance liquid chromatography, photolabel-containing peptides generated by tryptic digestion were isolated. This identified a portion of the adenine ring binding domain of GDH isoproteins as in the region containing the sequence, EMSWIADTYASTIGHYDIN. Photolabeling of the peptide was prevented over 90% by the presence of 1 mM ADP during photolysis, while other nucleotides could not reduce the amount of photoinsertion as effectively as ADP. These results demonstrate selectivity of the photoprobe for the ADP binding site and suggest that the photolabeled peptide with the residues Glu179-Asn197 is within the ADP binding domain of the brain GDH isoproteins.

Different antigenic reactivities of bovine brain glutamate dehydrogenase isoproteins

The structural differences between two types of glutamate dehydrogenase (GDH) isoproteins (GDH I and GDH II), homogeneously isolated from bovine brain, were investigated using a biosensor technology and monoclonal antibodies. A total of seven monoclonal antibodies raised against GDH II were produced, and the antibodies recognized a single protein band that comigrates with purified GDH II on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblot. Of seven anti-GDH II monoclonal antibodies tested in the immunoblot analysis, all seven antibodies interacted with GDH II, whereas only four antibodies recognized the protein band of the other GDH isoprotein, GDH I. When inhibition tests of the GDH isoproteins were performed with the seven anti-GDH II monoclonal antibodies, three antibodies inhibited GDH II activity, whereas only one antibody inhibited GDH I activity. The binding affinity of anti-GDH II monoclonal antibodies for GDH II (K(D) = 1.0 nM) determined using a biosensor technology (Pharmacia BIAcore) was fivefold higher than for GDH I (K(D) = 5.3 nM). These results, together with epitope mapping analysis, suggest that there may be structural differences between the two GDH isoproteins, in addition to their different biochemical properties. Using the anti-GDH II antibodies as probes, we also investigated the cross-reactivities of brain GDHs from some mammalian and an avian species, showing that the mammalian brain GDH enzymes are related immunologically to each other.

Effects of 2-bromopropane on spermatogenesis in the Sprague-Dawley rat

In 1995, 2-bromopropane (2-BP) was associated with occupational reproductive and hematopoietic toxicity in Korea. The effect of 2-BP on spermatogenesis, or Leydig cells, has not been determined in adult rats. In the present study, 40 ten-week-old Sprague-Dawley (SD) rats were treated orally with 3.5 g/kg/d of 2-BP for 3 consecutive days. At 1, 3, 5, 7, 14, 28, 42, and 70 d after treatment, testes were perfused with Karnovsky's solution or immersed in Bouin's solution, embedded in plastic or Epon and evaluated with light and electron microscopy. DNA ploidy distributions of testicular suspensions were determined by flow cytometry, which allowed comparison of quantitative spermatogenesis with histopathologic observations. Degeneration of spermatogonia was observed during Stages I-IV in seminiferous tubules on Day 1 after treatment. Spermatocytes, spermatids, Sertoli cells, and Leydig cells appeared normal in the early stage of the study. Whereas spermatid retention in Stages IX-XI was observed on Day 7 after treatment, depletion of spermatocytes and spermatids continued over time, followed by a marked increase of germ cells on Day 42 after treatment. However, the seminiferous tubules did not completely recover by study termination. Leydig cell cellularity increased mildly without any significant morphologic modification at the end of the study. Immunohistochemistry using an antibody against proliferating cell nuclear antigen (PCNA), showed an increased number of immunoreactive Leydig cells in the interstitium. In the flow cytometry analysis, proportions of diploid and tetraploid cells gradually decreased time-dependently until Day 28 after treatment, but showed an increase on Day 42, followed by a decrease on Day 70 after treatment. These data are strengthened by qualitative descriptions of lesions observed by histopathology. These results suggest that a high dose of 2-BP can decrease spermatogenesis by adversely affecting spermatogonia followed by depletion of spermatocytes, spermatids, and spermatozoa, with subsequent testicular atrophy. The atrophied testes may not regenerate completely. The number of Leydig cells may increase mildly with 10 weeks of recovery.

Isolation and identification of succinic semialdehyde dehydrogenase inhibitory compound from the rhizome of Gastrodia elata Blume

In our search for the anticonvulsant constituent of Gastrodia elata repeated column chromatographies guided by activity assay led to isolation of an active compound, which was identified as gastrodin on the basis of spectral data. Brain succinic semialdehyde dehydrogenase (SSADH) was inactivated by preincubation with gastrodin in a time-dependent manner and the reaction was monitored by absorption and fluorescence spectroscopic methods. The inactivation followed pseudo-first-order kinetics with the second-rate order constant of 1.2 x 10(3) M-1min-1. The time course of the reaction was significantly affected by the coenzyme NAD+, which affected complete protection against the loss of the catalytic activity, whereas substrate succinic semialdehyde failed to prevent the inactivation of the enzyme. It is postulated that the gastrodin is able to elevate the neurotransmitter GABA levels in central nervous system by inhibitory action on one of the GABA degradative enzymes, SSADH.

Expression of Th1 and Th2 type cytokines responding to HBsAg and HBxAg in chronic hepatitis B patients

The cytokine pattern on viral antigen recognition is believed to exert a profound influence on the resolution of viral infections and viral clearance. This study was initiated to investigate whether a cytokine imbalance oriented toward Th2 type response plays a role in chronic hepatitis B. Cytokine profiles of peripheral blood mononuclear cells associated with chronic hepatitis B were analysed by RT-PCR. Upon HBsAg stimulation, expression of IFN-gamma, IL-2, IL-4, and IL-10 was detected in 41%, 8%, 41%, and 50% of the patients, respectively. Among these cytokines, the expression of IFN-gamma was associated with high levels of serum AST/ALT. However, we could not prove that Th2 type cytokines had a protective effect on hepatocytes. Upon HBxAg stimulation, there was no recognizable association of cytokine patterns with AST/ALT levels. In conclusion, production of a Th1 cytokine, IFN-gamma, by HBsAg-reactive cells was associated with hepatocyte damage in chronic hepatitis B, while no counteracting effect of Th2 cytokines produced by those cells was observed.

Reactive cysteine residue of bovine brain glutamate dehydrogenase isoproteins

Protein chemical studies of glutamate dehydrogenase isoproteins (GDH I and GDH II) from bovine brain reveal that one cystein residue is accessible for reaction with thiol-modifying reagent. Reaction of the two types of GDH isoproteins with p-chloromercuribenzoic acid resulted in a time-dependent loss of enzyme activity. The inactivation followed pseudo first-order kinetics with the second-order rate constant of 83 M(-1) s(-1) and 75 M(-1) s(-1) for GDH I and GDH II, respectively. The inactivation was partially prevented by preincubation of the glutamate dehydrogenase isoproteins with NADH. A combination of 10 mM 2-oxoglutarate with 2 mM NADH gave complete protection against the inactivation. There were no significant differences between the two glutamate dehydrogenase isoproteins in their sensitivities to inactivation by p-chloromercuribenzoic indicating that the microenvironmental structures of the GDH isoproteins are very similar to each other. Allosteric effectors such as ADP and GTP had no effects on the inactivation of glutamate dehydrogenase isoproteins by thiol-modifying reagents. By a combination of peptide mapping analysis and labeling with [14C] p-chloromercuribenzoic acid, a reactive cystein residue was identified as Cys323 in the overall sequence. The cysteine residue was clearly identical to sequences of other GDH species known.

Identification of an NAD+ binding site of brain glutamate dehydrogenase isoproteins by photoaffinity labeling

Photoaffinity labeling with [32P]nicotinamide 2-azidoadenosine dinucleotide (2N3NAD+) was used to identify the NAD+ binding site within two types of glutamate dehydrogenase isoproteins (GDH I and GDH II) isolated from bovine brain. In the absence of photolysis, 2N3NAD+ is a substrate for the GDH isoproteins. When the enzymes were covalently modified by photolysis in the presence of saturating amounts of photoprobe, about 50% inhibition of the GDH activities was observed. Photoinsertion of probe was increased by GTP or glutarate and decreased by NAD+ or ADP. With the combination of immobilized boronate affinity chromatography and reversed-phase HPLC, photolabel-containing peptides generated with trypsin were isolated. This identified a portion of the adenine ring binding domain of GDH isoproteins as the region containing the sequence, CIAVGXSDGSIWNPDGIDPK for both GDH isoproteins, corresponding to Cys270 through Lys289 of the amino acid sequence of well known bovine liver GDH. The X indicates a position for which no phenylthiohydantoin-derivative could be assigned. The missing residue, however, can be designated as a photolabeled glutamate since the sequences including the glutamate residue in question have a complete identity with those of the other GDH species known. Photolabeling of these peptides was prevented by the presence of NAD+ during photolysis. These results demonstrate selectivity of the photoprobe for the NAD+ binding site and suggest that the peptide identified using the photoprobe is located in the NAD+ binding domain of the brain GDH isoproteins. Both amino acid sequencing and compositional analysis identified Glu275 as the site of photoinsertion.

Helicobacter pylori infection, oxidative DNA damage, gastric carcinogenesis, and reversibility by rebamipide

Several epidemiological studies have demonstrated a close association between Helicobacter pylori infection and carcinoma of the mid- or distal stomach. If this can be shown to be a causal association, eradication of the organism may prevent later development of cancer. Several mechanisms have been proposed by which H. pylori infection might lead to predisposition for gastric cancer. Although many potential pathogenic mechanisms, such as increased proliferative gastric epithelial response to H. pylori, lowered gastric ascorbic acid levels, and high occurrences of atrophic gastritis, have been proposed, there is little evidence as to which might be of direct importance to such H. pylori-related disease in vivo. H. pylori-associated inflammation may interact with other causal factors related to gastric carcinogenesis and can result in the intestinal type of gastric cancer and then DNA damage due to oxygen radicals induced by persistent inflammatory cell infiltrations in the gastric mucosa may lead to alterations of the gene and result in the development of diffuse-type carcinoma. In order to know the influence of H. pylori on changes of inflammation-related DNA damage, we measured the sequential changes of 8-hydroxydeoxyguanosine (8-OHdG) contents of DNA and the changes of two biomarkers inducible nitric oxide synthase (iNOS) and apoptosis from human gastric mucosa according to the status of H. pylori. The increased levels of oxidative DNA damage, increased occurrences of apoptosis, and increased expressions of iNOS seem to provide the mechanistic links between H. pylori infection and gastric carcinogenesis and rebamipide can abrogate the levels of these hazard factors.

Quantitative and qualitative usefulness of rebamipide in eradication regimen of Helicobacter pylori

The aim of the present study was to determine the efficacy of a new combination regimen including antioxidant, proton pump inhibitor, and antibiotics against Helicobacter pylori and to document the changes of oxidative stress and cytokines involved in H. pylori-associated gastritis. From each of 57 patients with endoscopically diagnosed gastric and/or duodenal ulcers associated with H. pylori infection, five gastric antral biopsy specimens were taken for the diagnosis of H. pylori and for experimental measures. The patients were then treated either with lansoprozole 30 mg + amoxicillin 1.5 g (LA group; 21 patients) or lansoprazole 30 mg + amoxicillin 1.5 g + rebamipide 300 mg (LAM group; 36 patients) for two weeks. Four weeks after the initiation of treatment, the patients were endoscoped again and biopsy specimens were obtained. Mucosal malondialdehyde (MDA) levels; myeloperoxidase (MPO) activities; superoxide dismutase; catalase; glutathione peroxidase; cytokines IL-1, IL-6, TNF-alpha; and chemokines IL-8, GRO-alpha, RANTES (regulated on activation normal T expressed and secreted) were measured. Using paraffin-embedded tissue sections, in situ terminal deoxyribonucleotide transferase (TdT) -mediated dUTP nick end labeling (TUNEL) for apoptosis and immunohistochemical staining for inducible nitric oxide synthase (iNOS) were performed. Two weeks of treatment with the LA regimen resulted in 57.4% eradication rates of H. pylori, whereas two weeks of treatment with the LAM regimen resulted in 75.0% eradication rates. Eradication rates between these two groups were statistically significantly different (P < 0.05). Mucosal MDA levels and MPO activities were significantly lower in the LAM group than the LA group. Mucosal levels of cytokines IL-1, IL-6, and TNF-alpha and of chemokines IL-8, GRO-alpha, and RANTES were all significantly decreased after the treatment of H. pylori, especially in the LAM-treated group. The apoptotic index and iNOS score were significantly reduced after the eradication of H. pylori. The addition of the antioxidative drug rebamipide to the eradication regimen against H. pylori has quantitative and qualitative advantages such as either augmenting the eradication rates of H. pylori or decreasing oxidative stress and cytokines levels generated by H. pylori infection.

Induction of apoptosis with an extract of Artemisia asiatica attenuates the severity of cerulein-induced pancreatitis in rats

The aim of this study was to test the hypothesis that apoptosis can protect against experimental pancreatitis and induction of apoptosis by an extract of Artemisia asiatica (DA-9601) is beneficial in cerulein-induced pancreatis in rats. Pancreatitis was induced in 6-week-old male SPF Sprague-Dawley rats by two intravenous (i.v.) administrations of 40 microg/kg cerulein. To investigate the effects of DA-9601 on the severity of pancreatitis and extent of apoptosis, rats were treated with intragastric DA-9601, 30 mg/kg (D30), 100 mg/kg (D100), or 300 mg/kg (D300), intraperitoneal superoxide dismutase, 10,000 U/kg (SOD), and i.v. gabexate mesilate, 40 mg/kg (Foy), three times (30 min before cerulein injection, 30 and 90 min after cerulein injection). The control group was administered vehicle alone. Ten rats were included in each treatment group and control group. Rats were sacrificed 5 h after cerulein treatment. Serum amylase, histological activity index (HAI), pancreatic lipid peroxide levels, and apoptotic index [in situ hybridization by terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling (TUNEL)] were determined. Gel electrophoresis was performed for the presence of DNA fragmentations. The results were as follows. Serum amylase was significantly increased in all cerulein-treated groups compared to normal controls (p < 0.001). The HAI was significantly decreased in only the D300 group compared to the controls (p < 0.05). The apoptotic index of the cerulein-alone group was 3.8 +/- 2.7, but the mean apoptotic indexes of the SOD and Foy groups were 16.4 +/- 4.6 and 13.3 +/- 1.8, respectively, a significant increase (p < 0.01). The apoptotic index was more significantly increased in the DA-9601-treated groups, dose dependently (8.4 +/- 3.4 in D30, 14.8 +/- 4.3 in D100, 24.2 +/- 4.7 in D300). A smearing pattern of DNA electrophoresis was noted in the DA-9601-treated groups. In conclusion, DA-9601, an extract of Artemisia, induced apoptosis of pancreatic acinar cells dose dependently and concomitantly attenuated the severity of pancreatitis.

Localization of hepatitis B virus DNA in hepatocellular carcinoma by polymerase chain reaction in situ hybridization

The polymerase chain reaction in situ hybridization (PCR-ISH) is a new technique that combines the sensitivity of PCR with the localizing ability of ISH. To investigate the expression pattern of hepatitis B virus (HBV) in the tissue of hepatocellular carcinoma (HCC), we detected HBV-DNA with PCR-ISH in paraffin-embedded tumor and corresponding non-tumor tissues from 11 HCC patients. HBV-DNA was detected in 4 of 11 tumor tissues and in 7 of 10 non-tumor tissues. In tumor tissues, positive signals were scattered in the tissue with occasional clustering, and were found mainly in the cytoplasm of HCC cells rather than in the nucleus. In non-tumor tissues, the number of positive signals was higher than in tumor tissues and they were found in regenerating nodules with differing patterns and intensities. When we compared the detection rate of PCR-ISH with nested PCR among 10 tissue samples, HBV-DNA was detected in 5 tissue samples by PCR-ISH, but the S gene was detected in 10, precore gene in 9 and X gene in 8 by nested PCR. The findings suggest that PCR-ISH is a sensitive technique for localizing HBV in tissue sections and that the low level of HBV replication persists in HCC cells.

Identification of three novel mutations and a high frequency of the Arg778Leu mutation in Korean patients with Wilson disease

Four mutations--R778L, A874V, L1083F, and 2304delC--in the copper-transporting enzyme, P-type ATPase (ATP7B), were identified in Korean Patients with Wilson disease. Arg778Leu, the most frequently reported mutation of this enzyme, was found in six of eight unrelated patients studied, an allele frequency of 37.5%, which is considerably higher than those in other Asian populations. The novel single nucleotide deletion, 2304delC, was found in one patient. Since a mutation at cDNA nucleotide 2302 (2302insC) had been previously described, this region of the ATP7B gene may be susceptible to gene rearrangements causing Wilson disease.

Identification of three novel mutations and a high frequency of the Arg778Leu mutation in Korean patients with Wilson disease

Four mutations--R778L, A874V, L1083F, and 2304delC--in the copper-transporting enzyme, P-type ATPase (ATP7B), were identified in Korean Patients with Wilson disease. Arg778Leu, the most frequently reported mutation of this enzyme, was found in six of eight unrelated patients studied, an allele frequency of 37.5%, which is considerably higher than those in other Asian populations. The novel single nucleotide deletion, 2304delC, was found in one patient. Since a mutation at cDNA nucleotide 2302 (2302insC) had been previously described, this region of the ATP7B gene may be susceptible to gene rearrangements causing Wilson disease.

Activation of two types of brain glutamate dehydrogenase isoproteins by gabapentin

The stimulatory effects of gabapentin on the activities of two types of glutamate dehydrogenase (GDH) isoproteins homogeneously purified from bovine brain have been studied at various conditions. When the effects of different gabapentin concentrations on GDH activities were studied in the direction of reductive amination of 2-oxoglutarate with NADPH as a coenzyme, a marked activation was observed for both isoproteins, whereas both isoproteins showed activation to a lesser extent with NADH as a coenzyme. Stimulatory effects of gabapentin on GDH activities in the direction of the oxidative deamination of glutamate were also observed, but to a much lesser extent than reductive amination. There were big differences between the two GDH isoproteins in their sensitivity to the action of gabapentin. The largest activation was observed with GDH II when NADPH was used as a coenzyme. Half-maximal stimulation was reached at around 1.5 mM. Gabapentin relieved the inhibition of GDH isoproteins by GTP and this resulted in an increase in the apparent activation by gabapentin in the presence of GTP. 2-Oxoglutarate was found to give rise to high substrate inhibition and gabapentin reduced the substrate inhibition in the presence of 0.2 mM NADH. Since there are neurodegenerative disorders in which GDH activity is decreased, the therapeutic modulation of the activity of this enzyme may be clinically useful.

Effects of transferrin on the modulation of cytokine production on mouse spleen cells

In order to investigate the the effects of transferrin(Tf) on the production of cytokines, mouse spleen cells were treated with various concentrations of apo- and holo-Tf, and then the production of IL-6, IFN gamma and the expression of mRNA for TNF alpha was determined. The distribution of Tf, macrophages and T cells in the mouse mammary glands was also examined. IL-6 and IFN gamma producing capabilities of the unstimulated spleen cells in the presence of apo and holo-Tf were increased in a dose dependent manner, while the cells stimulated with anti-CD3 had no significant effects on production in thd presence of graded concentrations of Tf. The relative abundance of TNF alpha mRNA was significantly affected by the concentration of TF. During early involution almost all of the secretory epithelial cells and the secretion in the alveoli showed a very strong positive reaction to transferrin antibody, and macrophages and T cells were distributed in the lumen, alveolar epithelial layer and connective tissue area. These findings suggest that the upregulated patterns of these cytokines and distribution of immune cells may play a beneficial role in the augmentation of host's defense mechanisms during involution.

Augmented eradication rates of Helicobacter pylori by new combination therapy with lansoprazole, amoxicillin, and rebamipide

The aim of the present study was to determine the efficacy of a new combination regimen including an antioxidant, a proton pump inhibitor, and antibiotics against Helicobacter pylori and to document the changes of oxidative stress and cytokines involved in H. pylori-associated gastric inflammation. From 57 patients with endoscopically diagnosed gastric and/or duodenal ulcers associated with H. pylori infection five gastric antral biopsy specimens were taken for the diagnosis of H. pylori and for the experimental measures. The patients were then treated either with lansoprazole 30 mg + amoxicillin 1.5 g (LA group; 21 patients) or lansoprazole 30 mg + amoxicillin 1.5 g + rebamipide 300 mg (LAM group; 36 patients) for two weeks. Four weeks after the initiation of treatment, the patients were endoscoped again and biopsy specimens were obtained. Mucosal malondialdehyde (MDA) levels; myeloperoxidase (MPO) activities; superoxide dismutase; catalase; glutathione peroxidase; cytokines IL-1, IL-6, TNF-alpha; and chemokines IL-8, GRO-alpha, RANTES (regulated on activation normal T expressed and secreted) were measured. Using paraffin-embedded tissue sections, in situ terminal deoxyribonucleotide transferase (TdT) mediated dUTP nick end labeling (TUNEL) for apoptosis and immunohistochemical staining for inducible nitric oxide synthase (iNOS) were performed. Two weeks of treatment with the LA regimen resulted in 57.4% eradication rates of H. pylori, whereas two weeks of treatment with the LAM regimen resulted in 75.0% eradication rates. Eradication rates between these two groups were statistically significantly different (P < 0.05). Mucosal MDA levels and MPO activities were significantly lower in the LAM group than the LA group. Mucosal levels of cytokines IL-1, IL-6, and TNF-alpha and of chemokines IL-8, GRO-alpha, and RANTES were all significantly decreased after the treatment of H. pylori, especially so in the LAM group. The apoptotic index and iNOS score were significantly reduced after the eradication of H. pylori. The addition of an antioxidative drug to the eradication regimen against H. pylori has advantages either in augmenting the eradication rates of H. pylori or in decreasing the oxidative stress and cytokines levels generated by H. pylori infection.

Possibility of chemoprevention by the eradication of Helicobacter pylori: oxidative DNA damage and apoptosis in H. pylori infection

OBJECTIVES

The purpose of this study was to study the changes of 8-hydroxydeoxyguanosine (8-OH-dG) contents of DNA from human gastric mucosa with or without Helicobacter pylori and the changes of two biomarkers, iNOS and apoptosis, in gastric biopsies obtained before and after the eradication of H. pylori.

METHODS

DNA isolated from the biopsied human gastric mucosa was digested to deoxynucleotides by nuclease P1, then with Escherichia coli alkaline phosphatase, and analyzed by HPLC-ECD system. 8-OH-dG content was expressed as the number of residues per 10(5) deoxyguanosine. iNOS immunohistochemical staining was performed with antihuman iNOS antiserum generated in mice at a dilution of 1:500, and in situ apoptosis was detected by in situ terminal deoxyribonucleotide transferase (TdT)-mediated dUTP nick end labeling. Both the density of H. pylori and the degree of inflammation were scored.

RESULTS

The 8-OH-dG contents of healthy normal controls with negative H. pylori were 4.31 +/- 2.33 (8-OH-dG/10(5) dG), whereas those of patients with positive H. pylori were 10.40 +/- 7.25. The difference between these two values was statistically significant (p < 0.01). The 8-OH-dG contents were significantly decreased after the eradication of H. pylori (12.22 +/- 2.09 vs. 2.42 +/- 1.22, p < 0.001). After the eradication of H. pylori, both the apoptotic index and the iNOS scores were significantly decreased, compared with those before eradication (3.72 +/- 1.74 vs. 1.17 +/- 1.06 for apoptosis and 10.34 +/- 6.79 vs. 1.43 +/- 1.14 for iNOS, p < 0.001). Statistically significant correlations were observed among apoptotic index, iNOS score, degree of inflammation, and density of H. pylori (p < 0.05).

CONCLUSIONS

The increased levels of oxidative DNA damage, increased occurrences of apoptosis, and increased expressions of iNOS suggest mechanistic links between H. pylori infection and gastric carcinogenesis.