Superoxide dismutase activity of iron(II)TPEN complex and its derivatives

Superoxide is involved in the pathogenesis of various diseases, such as inflammation, ischemia-reperfusion injury and carcinogenesis. Superoxide dismutases (SODs) catalyze the disproportionation reaction of superoxide to produce oxygen and hydrogen peroxide, and can protect living cells against the toxicity of free radicals derived from oxygen. Thus, SODs and their functional mimics have potential value as pharmaceuticals. We have previously reported that Fe(II)tetrakis-N,N,N',N'-(2-pyridylmethyl)ethylenediamine (Fe(II)TPEN) has an excellent SOD activity (IC50 = 0.5 microM) among many iron complexes examined (J. Biol. Chem., 264, 9243-9249 (1989)). Fe(II)TPEN can act like native SOD in living cells, and protect Escherichia coli cells from free radical toxicity caused by paraquat. In order to develop more effective SOD functional mimics, we synthesized Fe(II)TPEN derivatives with electron-donating or electron-withdrawing groups at the 4-position of all pyridines of TPEN, and measured the SOD activities and the redox potentials of these complexes. Fe(II) tetrakis-N,N,N',N'-(4-methoxy-2-pyridylmethyl)ethylenediamine (Fe(II)(4MeO)4TPEN) had the highest SOD activity (IC50 = 0.1 microM) among these iron-based SOD mimics. In addition, a good correlation was found between the redox potential and the SOD activity of 15 Fe(II) complexes, including iron-based SOD mimics reported in the previous paper (J. Organometal. Chem., in press). Iron-based SOD mimics may be clinically applicable, because these complexes are generally tissue-permeable and show low toxicity. Therefore our findings should be significant for the development of clinically useful SOD mimics.

ICTS, an interventional cardiology training system

In this article, we present an Interventional Cardiology Training System developed by the Medical Application Group at Mitsubishi Electric in collaboration with the Center for Innovative Minimally Invasive Therapy. The core of the ICTS is a computer simulation of interventional cardiology catheterization. This simulation integrates clinical expertise, research in learning, and technical innovations to create a realistic simulated environment. The goal of this training system is to augment the training of new cardiology fellows as well as to introduce cardiologists to new devices and procedures. To achieve this goal, both the technical components and the educational content of the ICTS bring new and unique features: a simulated fluoroscope, a physics model of a catheter, a haptic interface, a fluid flow simulation combined with a hemodynamic model and a learning system integrated in a user interface. The simulator is currently able to generate--in real-time--high quality x-ray images from a 3D anatomical model of the thorax, including a beating heart and animated lungs. The heart and lung motion is controlled by the hemodynamic model, which also computes blood pressure and EKG. The blood flow is then calculated according to the blood pressure and blood vessel characteristics. Any vascular tool, such as a catheter, guide wire or angioplasty balloon can be represented and accurately deformed by the flexible tool physics model. The haptics device controls the tool and provides appropriate feedback when contact with a vessel wall is detected. When the catheter is in place, a contrast agent can be injected into the coronary arteries; blood and contrast mixing is computed and a visual representation of the angiogram is displayed by the x-ray renderer. By bringing key advances in the area of medical simulation--with the real-time x-ray renderer for instance--and by integrating in a single system both high quality simulation and learning tools, the ICTS opens new perspectives for computer based training systems.

High expression of the second lysine decarboxylase gene, ldc, in Escherichia coli WC196 due to the recognition of the stop codon (TAG), at a position which corresponds to the 33th amino acid residue of sigma38, as a serine residue by the amber suppressor, supD

Escherichia coli WC196, which was obtained from the strain W3110 by nitrosoguanidine mutagenesis as an overproducer of lysine, produced approximately twenty times more cadaverine than did W3110, and had a twenty fold higher level of rpoS gene product, sigma38, than in W3110. Both WC196 and W3110 had a stop codon (TAG) in rpoS at position which corresponds to the 33th residue of sigma38 protein. In addition, WC196 but not W3110 had a mutation in the gene encoding Ser-tRNA (SerU), called, supD. Analysis of the amino acid sequence of a sigma38 preparation from WC196 showed that the 33th residue of sigma38 is a serine residue. The deltarpoS deltacadA mutant of E. coli W3110 harboring the plasmid containing rpoS, in which the TAG codon was converted to a TCG codon for serine-33 residue of sigma38, expressed a significant amount of Ldc and accumulated a large amount of sigma38. However, the deltarpoS deltacadA mutant of W3110 with the plasmid containing the intact rpoS from W3110 could synthesize neither sigma38 nor Ldc significantly.

Expression of perforin and Fas ligand mRNA in the liver of viral hepatitis

Cytotoxic T lymphocytes (CTLs) play an important role in the pathogenesis of viral hepatitis. We studied the expression of mRNAs of perforin and Fas ligand (Fas-L) in biopsy specimens from chronic hepatitis B (CHB) (15 cases) and hepatitis C (CHC) patients (13 cases). Both perforin and Fas-L mRNAs were detected in all cases of both CHB and CHC. No messages were detected in the control livers from two cases of fatty liver, a case of Gilbert's syndrome, and a case of Dubin-Johnson syndrome. Semiquantitative analysis revealed a positive correlation between the intensity of perforin and Fas-L mRNAs in both CHB and CHC. In CHB, the intensity of both perforin and Fas-L mRNAs showed a positive correlation with the histological activity and serum alanine aminotransferase level, while the correlation was not apparent in CHC. These results suggest that both perforin and Fas/Fas-L systems are involved in the pathogenesis of liver cell injury of CHB and CHC.

Precursor genes of future pandemic influenza viruses are perpetuated in ducks nesting in Siberia

Influenza A viruses of different subtypes were isolated from fecal samples of ducks in their nesting areas in Siberia in summer from 1996 to 1998. Phylogenetic analysis of the NP genes of the isolates in Siberia and those in Hokkaido, Japan on their flyway of migration from Siberia to the south in autumn revealed that they belong to the Eurasian lineage of avian influenza viruses. It is noted that the genes of the isolates in Siberia are closely related to those of H5N1 influenza virus strains isolated from chickens and humans in Hong Kong in 1997 as well as to those of isolates from domestic birds in southern China. The results indicate that influenza viruses perpetuated in ducks nesting in Siberia should have contributed genes in the emergence of the H5N1 virus in Hong Kong. Vaccine prepared from avirulent A/duck/Hokkaido/4/96 (H5N3) influenza virus was potent enough to protect mice from challenge with lethal dose of the pathogenic H5N1 virus [19]. Intensive surveillance study of aquatic birds especially in Siberia is, therefore, stressed to provide information on the future pandemic influenza virus strains and for vaccine preparation.

Molecular characterization of a novel gamma-glutamyl transpeptidase homologue found in rat brain

A cDNA clone for a novel homologue to gamma-glutamyl transpeptidase (gamma-GTP), termed GTPH, was isolated from a rat brain expression cDNA library using antisera against total brain synaptosomal fractions. The cloned GTPH consists of 641 amino acid residues (78 kDa) and exhibits structural similarity with a conventional type of gamma-GTP that is predominantly expressed in the liver: They share significant amino acid homology (33% identity, 73% similarity) spanning over the entire sequence. RNA analyses revealed that GTPH mRNA expression is found only in the nervous system, including all brain regions, eyes and peripheral ganglia, and increases during development. Endogenous GTPH protein is a membrane-bound glycoenzyme and migrates as 90-100 kDa in polyacrylamide gels. Taken together, GTPH is a novel form of a gamma-GTP-like molecule expressed exclusively in the nervous system.

Adrenomedullin and nitric oxide inhibit human endothelial cell apoptosis via a cyclic GMP-independent mechanism

Adrenomedullin, which was discovered as a vasodilating peptide, has been reported to be produced in various organs, in which adrenomedullin regulates not only vascular tone but also cell proliferation and differentiation in an autocrine/paracrine manner. We evaluated the effect of adrenomedullin on endothelial cell apoptosis. Human umbilical vein endothelial cells underwent apoptosis when cultured in serum-free medium. Treatment with adrenomedullin reduced the number of cells with pyknotic nuclei (Hoechst 33258 staining) and inhibited cell death (dimethylthiazol-diphenyltetrazolium bromide assay) in a dose-dependent manner. The administration of adrenomedullin did not alter the expression levels of Bcl-2 family proteins. Experiments with analogs of cAMP or a cAMP-elevating agonist demonstrated that elevation of the intracellular cAMP concentration does not mediate the antiapoptotic effect of adrenomedullin. The coadministration of N-nitro-L-arginine methyl ester (2 mmol/L), an inhibitor of nitric oxide synthase, abrogated the effect of adrenomedullin. Lower doses of sodium nitroprusside (1 to 10 micromol/L), a nitric oxide donor, mimicked the antiapoptotic effect of adrenomedullin. The antiapoptotic effect of sodium nitroprusside was not attenuated by the inhibition of soluble guanylyl cyclase with 1 micromol/L oxadiazolo-quinoxalin-1-one nor could apoptosis be inhibited by the incubation of human umbilical vein endothelial cells with 1 mmol/L 8-bromo-cGMP, a cell-permeant cGMP analog. These results indicate that adrenomedullin and nitric oxide inhibit endothelial cell apoptosis via a cGMP-independent mechanism.

A2-Pancortins (Pancortin-3 and -4) are the dominant pancortins during neocortical development

We have identified a novel mouse gene named pancortin that is expressed dominantly in the mature cerebral cortex. This gene produces four different species of proteins, Pancortin-1-4, sharing a common region in the middle of their structure with two variations at the N-terminal (A1 or A2 part) and C-terminal (C1 or C2 part) sides, respectively. In the present study, we showed that expression of mRNAs for A2-Pancortins (Pancortin species that contain the A2 part, i.e., Pancortin-3 and -4) is more dominant than that of mRNAs for A1-Pancortins (Pancortin species that contain the A1 part, i.e., Pancortin-1 and -2) in the prenatal mouse cerebral neocortex. Using western blot analysis, we found that substantial amounts of both A2-Pancortins were present in the prenatal cerebral neocortex and P19 cells after inducing neuronal differentiation. A2-Pancortins were still present in the cerebral neocortex of the adult, although their mRNAs were hardly detected. In contrast, the amount of A1-Pancortins did not increase after the third postnatal week in spite of their intense gene expression. Furthermore, we showed that recombinant Pancortin-3, one of the A2-Pancortins, was a secreted protein, in contrast to Pancortin-1 (one of the A1-Pancortins). These results suggest that A2-Pancortins are extracellular proteins essential for neuronal differentiation and that their molecular behavior is distinct from that of A1-Pancortins.

[Malignant pheochromocytoma with remarkable response to CVD chemotherapy--a case report]

A 60-year-old man was admitted to our hospital with the chief complaint of a left upper abdominal mass. 131I-MIBG scintiscan revealed a left upper abdominal mass, and the patient's serum catecholamine level was very high. Our diagnosis was pheochromocytoma of the left adrenal gland. On Oct. 19, 1995, a left nephrectomy and adrenectomy were performed. The serum catecholamine level then decreased and blood pressure was normalized. Two years later, it became difficult to control the patient's hypertension, and multiple metastatic liver cancer was found by an abdominal CT scan. The diagnosis of malignant pheochromocytoma was confirmed by the accumulation of 131I-MIBG in the liver. We started CVD chemotherapy. After 10 cycles of this chemotherapy, the serum catecholamine level was almost normalized and the metastatic liver cancer was reduced to one-third in size.

Dorsal induction from dorsal vegetal cells in Xenopus occurs after mid-blastula transition

We performed some experiments to investigate the temporal and spatial details of the dorsal induction exerted by dorsal vegetal cells in Xenopus embryo. Two dorsal vegetal cells (D1 cells) were transplanted into the ventral vegetal region of a recipient at the 32-cell stage. At various times after transplantation, the ventral animal-equatorial part was explanted and cultured. The explants isolated 5.5 h after transplantation (time 5.5) elongated and formed somites. In RT-PCR analysis, the expression of dorsal gene, chordin was activated in the explants isolated after time 4.0 (about the 4000-cell stage which corresponds to the mid blastula transition (MBT)) at control stage 10. In another series of experiments, ventral animal-equatorial and dorsal vegetal parts were isolated from the 4000-cell stage embryos and they were combined for 2.0-2.5 h. These ventral animal-equatorial explants elongated and formed somites. The chordin expression was also observed in the explants. But the 32- and 256-cell stage dorsal vegetal cells failed to exert the dorsalizing activity within the 2.0-2.5 h of the conjugation. These results suggest that 2 h contact after MBT is necessary and sufficient for the dorsal induction from the dorsal vegetal cells and it occurs as a result of the zygotic gene expression. Consistent with this idea, the zygotic dorsal genes, siamois and chordin were expressed on the upper regions of the transplanted D1 descendants at stage 10. Furthermore, this region began to gastrulate when the D1 cell was transplanted with upside-down orientation. Our data indicate that the upper region of the D1 descendants by itself act as the Spemann organizer rather than the Nieuwkoop center.

Effects of Dai-kenchu-to on levels of 5-hydroxytryptamine (serotonin) and vasoactive intestinal peptides in human plasma

We examined the effects of Dai-kenchu-to (DKCT) on the levels of vasoactive intestinal peptide (VIP) and 5-hydroxytryptamine (serotonin; 5-HT) in plasma taken from 6 healthy subjects. A single oral administration of 7.5 g DKCT caused significant increases in plasma VIP at 30, 60 to 90 and 120 min (3.5-5.5 pg/ml), compared with the response in a placebo group (about 1.0 pg/ml). DKCT also caused significant increases in plasma 5-HT at 30 (121.8+/-7.3 ng/ml) and 60 (156.5+/-8.0 ng/ml) min, compared with the response in the placebo group (about 101 ng/ml). These results indicate that the stimulatory effect of DKCT on VIP-immunoreactive substance (VIP-IS) secretion is due, at least in part, to increased 5-HT levels in the abdomen. As a consequence, increased VIP-IS may improve feelings of coldness in the abdomen.

[Giant osteoma of the temporal bone with otitis media: a case study]

A 71-year-old female presented with a giant osteoma of the right temporal bone and otitis media. Computed tomography (CT) and magnetic resonance imaging (MRI) confirmed the presence of the giant osteoma. An operation was performed to alleviate the difficult-to-treat otitis media and to address the related cosmetic problem. During the operation, three-dimensional CT (3D-CT) was very helpful in understanding the relationship between the tumor and the peripheral structures. Removal of the tumor improved the patient's otitis media. Osteoma of the temporal bone is rare. Only twenty-one cases of mastoid osteoma have been reported in Japan. In the present study, we review osteomas of the temporal bone and discuss their management.

Lactoferrin protects against UV-B irradiation-induced corneal epithelial damage in rats

PURPOSE

Lactoferrin supplementation suppresses ultraviolet light B (UV-B)-induced oxidation of cultures of human corneal epithelial cells. To investigate the protective effect of lactoferrin containing eyedrops against UV-B-induced corneal damage in vivo, we examined lactoferrin efficacy in a rat UV-B keratitis model.

METHODS

Sprague-Dawley rats were irradiated with >10 kJ/m2 after anesthetization, and then corneal epithelial defect was observed at 24 h postirradiation. The pre- or postapplication of vehicle or lactoferrin-containing eyedrops was performed, and then corneal epithelial damage was scored based on fluorescein staining.

RESULTS

Posttreatment with lactoferrin did not inhibit the extent of corneal damage and did not affect wound healing. However, pretreatment by topical application of lactoferrin suppressed development of a corneal epithelial defect induced by UV-B irradiation in rats.

CONCLUSION

These results suggest that the presence of lactoferrin in human tear fluid may inhibit UV-induced corneal epithelial damage.

Mechanism of superoxide dismutase-like activity of Fe(II) and Fe(III) complexes of tetrakis-N,N,N',N'(2-pyridylmethyl)ethylenediamine

The superoxide dismutase (SOD) activity of iron(II) tetrakis-N,N,N',N'(2-pyridylmethyl)ethylenediamine complex (Fe-TPEN) was reexamined using a pulse radiolysis method. In our previous study (J. Biol. Chem., 264, 9243-9249 (1989)), we reported that this complex has a potent SOD activity in a cyt. c (cytochrome c)-based system (IC50 = 0.8 microM) and protects E. coli cells against paraquat toxicity. The present pulse radiolysis experiment revealed that Fe(II)TPEN reacts stoichiometrically with superoxide to form Fe(III)TPEN with a second-order rate constant of 3.9 x 10(6) M-1 S-1 at pH 7.1, but superoxide did not reduce Fe(III)TPEN to Fe(II)TPEN. The reaction of Fe(III)TPEN and superoxide was biphasic. In the fast reaction, an adduct (Fe(III)TPEN-superoxide complex) was formed at the second-order rate constant of 8.5 x 10(5) M-1 S-1 at pH 7.4. In the slow one, the adduct reacted with another molecule of the adduct, regenerating Fe(III)TPEN. In the cyt. c method with catalase, this Fe(III)TPEN-superoxide complex showed cyt. c oxidation activity, which had led to overestimation of its SOD activity. Based on the titration data, the main species of complex in aqueous media at neutral pH was indicated to be Fe(III)TPEN(OH-). A spectral change after the reduction with hydrated electron indicates that the OH- ion coordinates directly to Fe(III) by displacing one of the pyridine rings. The X-ray analysis of [Fe(II)TPEN]SO4 supported this structure. From the above results we propose a novel reaction mechanism of FeTPEN and superoxide which resembles a proton catalyzed dismuting process, involving Fe(III)TPEN-superoxide complex.

Cytokine profile in the liver of primary biliary cirrhosis

We characterized the cytokine profile in the liver of patients with primary biliary cirrhosis (PBC). Total RNA was extracted from the biopsy specimens of 9 patients with early-stage PBC, 10 with chronic hepatitis C (CHC), and 4 normal controls. cDNA was prepared and amplified with a polymerase chain reaction using primers for interferon (IFN)-gamma and interleukin (IL)-2, -4, -5, -6, -10, -12 (p40), and -15. Cytokines such as IFN-gamma and IL-5, -6, -10, -12, and -15 were expressed in most cases of PBC. Expression rates of IL-5 and IL-6 were higher than in CHC and controls. The higher expression rate of IL-5 in PBC was associated with eosinophil infiltration. IL-2 and IL-4 were rarely detected. Semiquantitative analysis revealed that the expression of IFN-gamma and IL-10 was reversed in PBC and CHC: high IFN-gamma and low IL-10 in PBC and high IL-10 and low IFN-gamma in CHC. These results suggest that cytokine expression is skewed in PBC and both Th1 and Th2 cytokines may play a role in the pathogenesis.

Infection of the erythroid cell line, KU812Ep6 with human parvovirus B19 and its application to titration of B19 infectivity

A human parvovirus B19 (B19) infectivity assay was developed using the erythroid cell line, KU812Ep6. KU812Ep6 was cloned for high efficiency infection with B19 in vitro, in the presence of erythropoietin by a limiting dilution method from the parent cell line, KU812. B19 was effectively propagated in KU812Ep6 and was detected for B19 antigens, VP1 and VP2. The titers of B19 positive sera measured with KU812Ep6 cells were in the range of 10(6) to 10(8) TCID50 ml. This KU812Ep6 infectivity assay had a 10(3)-10(4.5) higher sensitivity than the colony forming unit-erythroid (CFU-e) injury assay. It was calculated that one TCID50 needed 10(3) B19 genome copies, judging from the infectivity assay and semi-quantitative PCR. The KU812Ep6 infectivity assay was also used to determine infectivity of B19 in vitro, and to evaluate inactivation, as well as clearance of the virus. The inactivation of B19 by heating was carried out and infectivity declined from 10(4) TCID50 ml to < 10 TCID50 ml (lower limit of detection) at 60 degrees C for 3 h or at 70 degrees C for 30 min, but only decreased to 10(2.5) TCID50 ml at 50 degrees C for 8 h.

Low frequency of genetic change in p53 immunopositive clones in human epidermis

Sun-exposed skin of Caucasians harbors thousands of p53-mutated clones, which are clinically invisible. Using whole mount immunostaining for p53 or Ki67 antigens, p53 sequencing, and loss of heterozygosity analysis, we have further characterised these clones. Loss of heterozygosity for the alleles examined is uncommon with the exception of 9q, which occurred in 28.3% of the samples. P53 clones are more common and larger in individuals with basal cell carcinoma than in control subjects (p < 0.03). Loss of heterozygosity is also more common in clones from individuals with basal cell carcinoma than in clones from subjects without a history of basal cell carcinoma, as would be expected if both relate to ultraviolet radiation exposure. p53 sequencing of clones is in keeping with the mutagenic role of ultraviolet radiation. Surprisingly, skin found to harbor p53 clones showed no clusters of Ki67 positive cells, unlike the situation for actinic keratoses or basal cell carcinomas. These results show that in human skin p53 mutation is not directly associated with genomic instability or abnormal cell cycling; that the p53 immunopositive clones are either genetically distinct or precursors to other squamous cell lesions of skin; and that p53 immunopositive clones are early lesions, in that gross disturbance of proliferation has not already occurred.

Incidence of skin cancers and precancerous lesions in Japanese--risk factors and prevention

An examination of the occurrence of skin cancers and precancerous lesions among residents of Kasai City (34 degrees 56' N) since 1992, and of le-island (25 degrees 10' N) since 1993, has been conducted to characterize the prevalence and incidence of skin cancers in Japanese people and to evaluate risk and preventive factors. The mean prevalence of actinic keratosis (AK) in residents of Kasai City and le-island was 203.33 and 756.26, respectively, indicating that twice the dose of UVB radiation causes a 3-4 fold higher incidence of AK, although life styles, including types of occupations, differ in these two locations. Working outdoors, having skin type I and/or a history of severe sunburns during childhood were found to be important risk factors, while the use of cosmetics after 20 years of age was a protective factor, for AK and possibly for skin cancers. Further, sunscreen use among males over 60 years of age in Kasai City from 1994 through 1998 suggested that sunscreen use may reduce AK development in older people. Four and 12 cases of skin cancers were found in residents of Kasai City (from 1992 to 1997) and on le-island (from 1993 to 1998), respectively. These numbers are too small to establish the prevalence of skin cancer in Japanese, but indicate that people living in areas of higher ambient solar radiation have a higher incidence of skin cancer. This epidemiological study strongly indicates that sun protection is the major modality to reduce sun-induced cutaneous tumors in Japanese.

Effect of galardin on collagen degradation by Pseudomonas aeruginosa

The authors examined the effect of a synthetic peptidyl hydroxamate inhibitor of matrix metalloproteinase, Galardin, on collagen degradation by Pseudomonas aeruginosa (P. aeruginosa) in the presence or absence of keratocytes. Type I collagen gels, with or without suspended keratocytes, were incubated under medium containing sterile P. aeruginosa culture broth and/or Galardin for 24 hr. Degradation of collagen fibrils during culture was measured by the release of hydroxyproline. The conditioned media were also subjected to gelatin zymography and Western blotting to analyse the activation, by P. aeruginosa factor(s), of matrix metalloproteinases (MMPs) released by keratocytes. The effects of protease inhibitors, aprotinin, leupeptin and pepstatin, on collagen degradation by P. aeruginosa were also examined. P. aeruginosa broth by itself induced collegen gel degradation. When keratocytes were present, P. aeruginosa broth increased the amount of degraded collagen even further. Galardin significantly reduced the amounts of collagen degraded by P. aeruginosa culture broth, whether keratocytes were present or absent in the gel. However, the protease inhibitors had no inhibitory effects on collagen degradation. Gelatin zymography and Western blotting revealed that inactive proMMP-1, -2 and -3, released by keratocytes, were converted to active forms in the presence of P. aeruginosa broth. Galardin decreased the amounts of active MMPs and increased those of inactive proMMPs, suggesting that Galardin inhibited the activation of proMMPs by P. aeruginosa. The present results suggest that Galardin inhibits the keratocyte-mediated collagen degradation by P. aeruginosa culture broth, resulting from preventing the conversion of proMMPs to active MMPs.