NADPH oxidase 4 is a critical mediator in Ataxia telangiectasia disease.

Ataxia telangiectasia (A-T), a rare autosomal recessive disorder characterized by progressive cerebellar degeneration and a greatly increased incidence of cancer among other symptoms, is caused by a defective or missing ataxia telangiectasia mutated (ATM) gene. The ATM protein has roles in DNA repair and in the regulation of reactive oxygen species (ROS). Here, we provide, to our knowledge, the first evidence that NADPH oxidase 4 (NOX4) is involved in manifesting A-T disease. We showed that NOX4 expression levels are higher in A-T cells, and that ATM inhibition leads to increased NOX4 expression in normal cells. A-T cells exhibit elevated levels of oxidative DNA damage, DNA double-strand breaks and replicative senescence, all of which are partially abrogated by down-regulation of NOX4 with siRNA. Sections of degenerating cerebelli from A-T patients revealed elevated NOX4 levels. ATM-null mice exhibit A-T disease but they die from cancer before the neurological symptoms are manifested. Injecting Atm-null mice with fulvene-5, a specific inhibitor of NOX4 and NADPH oxidase 2 (NOX2), decreased their elevated cancer incidence to that of the controls. We conclude that, in A-T disease in humans and mice, NOX4 may be critical mediator and targeting it will open up new avenues for therapeutic intervention in neurodegeneration.

Endothelial cell-derived endothelin-1 is involved in abnormal scar formation by dermal fibroblasts through RhoA/Rho-kinase pathway.

Hypertrophic scars and keloids are characterized by excessive dermal deposition of extracellular matrix due to fibroblast-to-myofibroblast differentiation. Endothelin-1 (ET-1) is primarily produced by vascular endothelial cells and plays multiple roles in the wound-healing response and organ fibrogenesis. In this study, we investigated the pathophysiological significance of ET-1 and involvement of RhoA, a member of the Rho GTPases, in hypertrophic scar/keloid formation. We found that ET-1 expression on dermal microvascular endothelial cells (ECs) in hypertrophic scars and keloids was higher than that in normal skin and mature scars. We also confirmed that ET-1 induced myofibroblast differentiation and collagen synthesis in cultured human dermal fibroblasts through the RhoA/Rho-kinase pathway. Finally, since hypertrophic scar/keloid formation was most prominent in areas exposed to mechanical stretch, we examined how mechanical stretch affected ET-1 secretion in human dermal microvascular ECs, and found that mechanical stretch increased ET-1 gene expression and secretion from ECs. Taken together, these results suggest that dermal microvascular ECs release ET-1 in response to mechanical stretch, and thereby contribute to the formation of hypertrophic scars and keloids through the RhoA/Rho-kinase pathway.

Effects of Breast Shielding during Heart Imaging on DNA Double-Strand-Break Levels: A Prospective Randomized Controlled Trial.

Purpose To examine the effect of breast shielding on blood lymphocyte deoxyribonucleic acid (DNA) double-strand-break levels resulting from in vivo radiation and ex vivo radiation at breast-tissue level, and the effect of breast shielding on image quality. Materials and Methods The study was approved by institutional review and commpliant with HIPAA guidelines. Adult women who underwent 64-section coronary computed tomographic (CT) angiography and who provided informed consent were prospectively randomized to the use (n = 50) or absence (n = 51) of bismuth breast shields. Peripheral blood samples were obtained before and 30 minutes after in vivo radiation during CT angiography to compare DNA double-strand-break levels by γ-H2AX immunofluorescence in blood lymphocytes. To estimate DNA double-strand-break induction at breast-tissue level, a blood sample was taped to the sternum for ex vivo radiation with or without shielding. Data were analyzed by linear regression and independent sample t tests. Results Breast shielding had no effect on DNA double-strand-break levels from ex vivo radiation of blood samples under shields at breast-tissue level (unadjusted regression: ß = .08; P = .43 versus no shielding), or in vivo radiation of circulating lymphocytes (ß = -.07; P = .50). Predictors of increased DNA double-strand-break levels included total radiation dose, increasing tube potential, and tube current (P < .05). With current radiation exposures (median, 3.4 mSv), breast shielding yielded a 33% increase in image noise and 19% decrease in the rate of excellent quality ratings. Conclusion Among women who underwent coronary CT angiography, breast shielding had no effect on DNA double-strand-break levels in blood lymphocytes exposed to in vivo radiation, or ex vivo radiation at breast-tissue level. At present relatively low radiation exposures, breast shielding contributed to an increase in image noise and a decline in image quality. The findings support efforts to minimize radiation by primarily optimizing CT settings. (©) RSNA, 2016 Clinical trial registration no. NCT02617888 Online supplemental material is available for this article.

Report of the international conference on regulatory endeavors towards the sound development of human cell therapy products.

The regulation of human cell therapy products is a key factor in their development and use to treat human diseases. In that regard, there is a recognized need for a global effort to develop a set of common principles that may serve to facilitate a convergence of regulatory approaches to ensure the smooth and efficient evaluation of products. This conference, with experts from regulatory agencies, industry, and academia, contributed to the process of developing such a document. Elements that could form a minimum consensus package of requirements for evaluating human cell therapy products were the overall focus of the conference. The important regulatory considerations that are unique to human cell therapy products were highlighted. Sessions addressed specific points that are different from those of traditional biological/biotechnological protein products. Panel discussions complemented the presentations. The conference concluded that most of the current regulatory framework is appropriate for cell therapy, but there are some areas where the application of the requirements for traditional biologicals is inappropriate. In addition, it was agreed that there is a need for international consensus on core regulatory elements, and that one of the major international organizations should take the lead in formulating such a consensus document.

Regulatory Frameworks for Gene and Cell Therapies in Japan.

The regulations for the human use of advanced therapy medical products such as gene and cell therapy products have evolved in accordance with advance of clinical experience, scientific knowledge, and social acceptance to these technologies. In Japan, two laws, the Pharmaceuticals and Medical Devices (PMD) Act and the Act on the Safety of Regenerative Medicine (ASRM), were enacted in November 2014. The PMD Act defines regenerative medical products for the first time and introduces a system for the conditional and time-limited marketing authorization of regenerative medical products. Under ASRM, the responsibilities of medical institutions to ensure the safety and provide transparency of such medical technologies are described. Amendments to accompanying guidelines for these two Acts are currently in preparation. It is expected that the new legislative frameworks will promote the timely development of new products and technologies, to bring safe and effective regenerative medicines to Japanese patients.

TiO2 ring-resonator-based EO polymer modulator.

In this work, an electro-optic (EO) ring resonator modulator was designed and fabricated in a waveguide consisting of a titanium dioxide (TiO)2 core, silicon dioxide (SiO2) buffer layer, EO polymer claddings, and electrodes. By optimizing the thickness of the TiO2 and SiO2layers, the modulator could satisfy the single-mode requirement; furthermore 52.5% TM mode was confined in the active EO polymer layers. The designed modulator could also pole the EO polymer effectively regardless of its resistivity. Therefore, the EO modulator was observed to show a high resonance wavelength shift of 2.25 × 10(-2) nm/V. The intensity modulation at 1550 nm showed a Vp-p = 1.9 V for a 3dB distinction ratio.

Nrf2-mediated induction of p62 controls Toll-like receptor-4-driven aggresome-like induced structure formation and autophagic degradation.

Toll-like receptors (TLRs) play a crucial role in several innate immune responses by regulating autophagy, but little is known about how TLR signaling controls autophagy. Here we demonstrate that p62/SQSTM1 is required for TLR4-mediated autophagy, which we show as selective autophagy of aggresome-like induced structures (ALIS). Treatment with LPS or Escherichia coli induced LC3(+) dot-like structures, and their assembly, but not lysosomal degradation, occurred independently of classic autophagic machinery. Microscopic and ultrastructural analyses showed that p62 is a component of the induced LC3(+) dots and these TLR4-induced p62(+) structures resemble ALIS. The levels of p62 mRNA and protein were increased in TLR4-activated cells and knockdown of p62 suppressed the ALIS formation and LC3-II conversion. The accumulation of p62 and ALIS required activation of Nrf2 by reactive oxygen species-p38 axis-dependent TLR4/MyD88 signaling, suggesting a link between innate immune and oxidative-stress responses. These findings indicate that TLR4-driven induction of p62 plays an essential role in the formation and the autophagic degradation of ALIS, which might be critical for regulating host defense.

Intranodal lymphangiography under microsurgery for refractory lymphatic ascites after pelvic lymphadenectomy.

Lymphatic ascites is a postoperative complication of lymph node dissection. Most symptomatic cases improve with conservative treatments. However, optimal management strategies for intractable lymphatic ascites remain controversial, and clinicians sometimes encounter intractable lymphatic ascites that does not respond to conservative management. We herein report a case of postoperative intractable lymphatic ascites that was successfully treated with intranodal lymphangiography (LG) from inguinal lymph nodes under microsurgery. A 56-year-old woman was diagnosed with stage II endometrial cancer and underwent total abdominal hysterectomy, bilateral salpingo-oophorectomy, and pelvic and para-aortic lymphadenectomies. On postoperative day (POD) 13, the patient presented with abdominal distention, and lymphatic ascites was diagnosed. Although the patient was treated with conservative management and lymphaticovenular anastomosis, her lymphatic ascites did not resolve. Finally, intranodal LG from the inguinal region was performed under microsurgery. A 2-cm incision was made on each side of the inguinal region. Once the lymph nodes were identified, a 23-gauge needle was inserted into the lymph node and lipiodol was injected. Extravasation of lipiodol into the abdomen from the left side of the lower pelvic region was confirmed. The postoperative course was uneventful. The ascites gradually decreased and disappeared within two weeks after LG.

Artemis-dependent DNA double-strand break formation at stalled replication forks.

Stalled replication forks undergo DNA double-strand breaks (DSBs) under certain conditions. However, the precise mechanism underlying DSB induction and the cellular response to persistent replication fork stalling are not fully understood. Here we show that, in response to hydroxyurea exposure, DSBs are generated in an Artemis nuclease-dependent manner following prolonged stalling with subsequent activation of the ataxia-telangiectasia mutated (ATM) signaling pathway. The kinase activity of the catalytic subunit of the DNA-dependent protein kinase, a prerequisite for stimulation of the endonuclease activity of Artemis, is also required for DSB generation and subsequent ATM activation. Our findings indicate a novel function of Artemis as a molecular switch that converts stalled replication forks harboring single-stranded gap DNA lesions into DSBs, thereby activating the ATM signaling pathway following prolonged replication fork stalling.

Parg deficiency confers radio-sensitization through enhanced cell death in mouse ES cells exposed to various forms of ionizing radiation.

Poly(ADP-ribose) glycohydrolase (Parg) is the main enzyme involved in poly(ADP-ribose) degradation. Here, the effects of Parg deficiency on sensitivity to low and high linear-energy-transfer (LET) radiation were investigated in mouse embryonic stem (ES) cells. Mouse Parg(-/-) and poly(ADP-ribose) polymerase-1 deficient (Parp-1(-/-)) ES cells were used and responses to low and high LET radiation were assessed by clonogenic survival and biochemical and biological analysis methods. Parg(-/-) cells were more sensitive to γ-irradiation than Parp-1(-/-) cells. Transient accumulation of poly(ADP-ribose) was enhanced in Parg(-/-) cells. Augmented levels of phosphorylated H2AX (γ-H2AX) from early phase were observed in Parg(-/-) ES cells. The induction level of p53 phophorylation at ser18 was similar in wild-type and Parp-1(-/-) cells and apoptotic cell death process was mainly observed in the both genotypes. These results suggested that the enhanced sensitivity of Parg(-/-) ES cells to γ-irradiation involved defective repair of DNA double strand breaks. The effects of Parg and Parp-1 deficiency on the ES cell response to carbon-ion irradiation (LET13 and 70 keV/µm) and Fe-ion irradiation (200 keV/µm) were also examined. Parg(-/-) cells were more sensitive to LET 70 keV/µm carbon-ion irradiation than Parp-1(-/-) cells. Enhanced apoptotic cell death also accompanied augmented levels of γ-H2AX in a biphasic manner peaked at 1 and 24h. The induction level of p53 phophorylation at ser18 was not different between wild-type and Parg(-/-) cells. The augmented level of poly(ADP-ribose) accumulation was noted after carbon-ion irradiation compared to γ-irradiation even in the wild-type cells. An enhanced poly(ADP-ribose) accumulation was further observed in Parg(-/-) cells. Both Parg(-/-) cells and Parp-1(-/-) cells did not show sensitization to Fe-ion irradiation. Parg deficiency sensitizes mouse ES cells to a wide therapeutic range of LET radiation through the effects on DNA double strand break repair responses and enhanced cell death.

Evaluation of the gamma-H2AX assay for radiation biodosimetry in a swine model.

There is a paucity of large animal models to study both the extent and the health risk of ionizing radiation exposure in humans. One promising candidate for such a model is the minipig. Here, we evaluate the minipig for its potential in γ-H2AX-based biodosimetry after exposure to ionizing radiation using both Cs137 and Co60 sources. γ-H2AX foci were enumerated in blood lymphocytes and normal fibroblasts of human and porcine origin after ex vivo γ-ray irradiation. DNA double-strand break repair kinetics in minipig blood lymphocytes and fibroblasts, based on the γ-H2AX assay, were similar to those observed in their human counterparts. To substantiate the similarity observed between the human and minipig we show that minipig fibroblast radiosensitivity was similar to that observed with human fibroblasts. Finally, a strong γ-H2AX induction was observed in blood lymphocytes following minipig total body irradiation. Significant responses were detected 3 days after 1.8 Gy and 1 week after 3.8 and 5 Gy with residual γ-H2AX foci proportional to the initial radiation doses. These findings show that the Gottingen minipig provides a useful in vivo model for validation of γ-H2AX biodosimetry for dose assessment in humans.

Improving the accuracy of estimating blood calcium concentration in Holstein cows using electrocardiographic variables.

We previously reported the possibility of using the electrocardiogram variable to estimate blood calcium (Ca) concentration in dairy cows based on the strong positive correlation between the blood Ca concentration and the inverse of the corrected ST peak interval (STc-1). To improve the accuracy of the estimation of blood Ca concentration, we investigated the relationship between blood Ca concentration and STc-1 for each postpartum day and available variables other than STc-1. We measured multiple variables (milk yield, calving number, age, body temperature, etc.), including serum total Ca concentration (tCa), blood ionized Ca concentration (iCa) and STc-1 in 462 Holstein cows on days 0, 1, 2, 3, 5, and 7 postpartum. A very high correlation was observed between iCa and tCa. The association between tCa and STc-1 for each postpartum day had a high coefficient of determination of 0.61-0.79 postpartum 0-2 days but decreased after the third day. In the investigation using the data from postpartum days 0-2, STc-1, heart rate interval, calving number, and age were highly correlated with tCa. In addition, a multiple regression equation was obtained with tCa as the objective variable and STc-1 and calving number as explanatory variables. The estimation accuracy was improved as compared with the simple regression equation using only STc-1 as the explanatory variable. This multiple regression equation was used for 11 cows suspected of having hypocalcemia, and it was able to correctly detect cows requiring early treatment, except for one cow.

Fat-augmented latissimus dorsi myocutaneous flap for total breast reconstruction: A report of 54 consecutive Asian cases.

Immediate fat grafting to the latissimus dorsi myocutaneous (LD) flaps is a breakthrough that addresses the issue of insufficient volume of LD. However, the use of this procedure in Asian patients has not yet been reported. Retrospective chart reviews were conducted on 54 Japanese cases of total breast reconstruction using fat-augmented LD flaps at our hospital from September 2017 to June 2019. There were 24 immediate reconstruction cases, 18 immediate two-stage reconstruction cases, nine delayed reconstruction cases, and three delayed two-stage reconstruction cases. Median age was 46 years (range, 29-69 years), and median body mass index was 21.5 (17-33.8). Median mastectomy specimen and flap weight was 225 g (123-993) and 225 g (130-796), respectively. The median volume of fat graft was 114 ml (46-305) for the LD flap and 58 ml (15-200) for the pectoralis major muscle. Of the 53 completed reconstruction cases, 38 (71.7%) achieved sufficient volume with the initial operation and six (11.3%) required additional fat grafting. The proportion of cases in the immediate reconstruction group, which achieved sufficient volume in the initial operation was significantly higher than those of the other three reconstruction groups (p = 0.007). Total breast reconstruction with fat-augmented LD flaps is a viable procedure for thin patients who have insufficient abdominal tissue, for those who wish to avoid abdominal scars, and for those in whom abdominal flaps have already been used. The procedure allows for large volume transplantation even with small skin paddles, which allows for smaller skin paddles to be designed without the need for extensive subcutaneous dissection.

Synthesis of a novel Sn(IV) porphycene-ferrocene triad linked by axial coordination and solvent polarity effect in photoinduced charge separation process.

A novel Sn(IV) porphycene-ferrocene triad molecule, trans-bis(ferrocenecarboxylato)(2,3,6,7,12,13,16,17-octaethylporphycenato)tin(IV), [Sn(IV)(OEPc)(FcCOO)(2)] (2), was synthesized and fully characterized by various spectroscopic methods. This is the first example of a metalloporphycene triad linked by the axial coordination of two functionalized units to a metallocenter. The steady-state fluorescence measurement indicated the efficient fluorescence quenching by coordination of the ferrocenecarboxylic acid in comparison to the corresponding dihydroxy-Sn(IV) porphycene, [Sn(IV)(OEPc)(OH)(2)] (1) (1, Phi(F) = 0.094; 2, Phi(F) = 0.01). The electron transfer process from the ferrocene units to the excited Sn(IV) porphycene was directly observed by subpicosecond transient absorption spectroscopy in acetonitrile (polar solvent) and toluene (nonpolar solvent). In acetonitrile, the transient species attributed to the Sn(IV) porphycene radical anion was observed at 750 and 850 nm within 1 ps after the excitation, and then the generated charge separation state disappeared with a value of 6.9 x 10(11) s(-1) for the time constant. On the other hand, the generated charge separation state decayed with two components, 3.9 x 10(11) and 9.6 x 10(9) s(-1) time constants, in toluene. For the observed two-component decay in toluene, a significant equilibrium between the charge separation state and the triplet state was proposed because these energy levels are close to each other. Therefore, the solvent-polarity-dependent long-lived charge separation state was obtained in the Sn(IV) porphycene-ferrocene triad system. The electron transfer upon excitation of the Sn(IV) porphyrin of [Sn(IV)(OEP)(FcCOO)(2)] (4), in which OEP denotes the 2,3,6,7,12,13,16,17-octaethylporphyrin ligand, was observed. However, no equilibrium between the charge separation and the triplet states was observed in both the acetonitrile and toluene. The difference in the charge recombination processes of the Sn(IV)-porphycene and -porphyrin is due to the small HOMO-LUMO gap and the large driving force (-DeltaG(CS)) of 2 compared to that of 4, which resulted in the energy level of the charge separation state close to the triplet state in toluene. Furthermore, the large driving force (-DeltaG(CS)) of 2 compared to that of 4 is attributed to the significant stabilization of the LUMO energy level caused by a decrease in the molecular symmetry and a large porphycene pi-electron framework. This result indicates that porphycenes are excellent candidates as an electron acceptor in photoinduced electron transfer systems.

Electron transfer in the supramolecular donor-acceptor dyad of zinc hemiporphycene.

In the present study, photoinduced electron transfer (ET) processes of supramolecular donor-acceptor dyads of Zn 2,3,7,8,11,12,17,18-octaethylhemiporphycene (ZnHPc) and axial ligands were investigated by using various spectroscopic methods. The formation of 1:1 dyads was confirmed by absorption spectral change during titration of axial ligand. The association constants were determined from the spectral change. Quenching of the fluorescence intensity was observed when electron acceptor ability of the axial ligand increased. The driving forces for ET were estimated based on the estimated redox potentials and structural parameters. It became clear that various ZnHPc dyads showed ET because of slightly higher donor-ability and larger excitation energy of ZnHPc when compared to the corresponding dyads of Zn porphycene (ZnPcn). The transient absorption spectra during the sub-picosecond laser flash photolysis showed the formation of charge separated state, that is, radical cation of ZnHPc and radical anion of axial ligand, from the singlet excited ZnHPc. The observed ET rates were compared with the previously reported values for Zn porphyrins and ZnPcn. The ET rates of ZnHPc were located between those observed with porphyrins and ZnPcn supramolecular dyads, even when the -DeltaG values were similar to each other. This observation was explained on the basis of the variation in reorganization energy and electronic coupling (V) values. Furthermore, distribution of HOMO electron density gave a plausible explanation for the variation in V values of these dyads.

A Simple and Scarless Method for Inframammary Fold Correction Using a Barbed Suture.

BACKGROUND: In the typical procedure for secondary correction of the inframammary fold (IMF) following breast reconstruction, a large incision is often required, and this increases surgical invasiveness. The "drawstring method" is a simple procedure for recreating a smooth IMF. We modified the drawstring method and developed an essentially scarless method for IMF correction from small stab incisions. METHODS: Patients at our hospital who presented with IMF ptosis or loss of definition after breast reconstruction and required IMF correction, as well as those who requested IMF recreation for the contralateral breast, during the period spanning May 2016 to June 2019 were considered for this study. We collected and analyzed demographic data, as well as complications and postoperative outcomes. RESULTS: The new method was performed on 20 patients, with the following breakdown: IMF recreation after breast reconstruction with a deep inferior epigastric artery perforator flap (11 patients), IMF recreation after breast reconstruction with a breast implant (2 patients), IMF recreation after breast reconstruction with fat graft (5 patients), and IMF recreation for the contralateral breast (2 patients). Overcorrection of the IMF stabilized by 2-3 months postoperatively, resulting in a smooth and well-defined IMF. For non-breast implant cases, the implant volume increased at the lower pole. Slack in the suture was observed in only 2 patients of the deep inferior epigastric artery perforator group and in 1 patient of the breast implant group after 6 months postoperatively. CONCLUSIONS: Our new method allows for the recreation of an essentially scarless, smooth, and well-defined IMF. IMF definition can be adjusted by altering the depth of the barbed suture. Since this method can be performed under local anesthesia, it offers the benefits of reducing medical costs and physical burden on patients.

Rad52 sumoylation and its involvement in the efficient induction of homologous recombination.

The protein Rad52 is a key player in various types of homologous recombination and is essential to maintenance of genomic integrity. Although evidence indicates that Rad52 is modified by SUMO, the physiological relevance of this sumoylation remains unclear. Here, we identify the conditions under which Rad52 sumoylation is induced, and clarify the role of this modification in homologous recombination. Oligomerization of Rad52 was a prerequisite for sumoylation, and the modification occurred in the cell proceeding S phase being exposed to the DNA-damaging agent methyl methanesulfonate (MMS). Following exposure to MMS, sumoylated Rad52 accumulated in rad51 cells, but not in the recombination-related gene mutants, rad54, rad55, rad59, sgs1, or srs2. The accumulation of sumoylated Rad52 was suppressed in rad51 cells expressing Rad51-K191R, an ATPase-defective protein presumed to be recruited to ssDNA. Although the sumoylation defective mutant rad52-3KR (K10R/K11R/K220R) showed no defect in mating-type switching, which did not lead to Rad52 sumoylation in wild-type cells, the mutant did demonstrate a partial defect in MMS-induced interchromosomal homologous recombination.

Syntheses and photophysical behavior of porphyrin isomer Sn(IV) complexes.

2,3,6,7,12,13,16,17-Octaethylhemiporphycenato Sn(IV) chloride, [Sn(IV)(OEHPc)Cl(2)], and 2,3,6,7,12,13,16,17-octaethylporphycenato Sn(IV) chloride, [Sn(IV)(OEPc)Cl(2)], were synthesized in high yields and fully characterized by various spectroscopic methods. The X-ray crystal structures of the Sn(IV) complexes with porphycene and hemiporphycene were determined for the first time. The photophysical and photochemical properties of the singlet state of the Sn(IV) porphycene and hemiporphycene complexes, structural isomers of porphyrin, have been investigated by fluorescence and phosphorescence spectroscopies. The relatively strong emission and long fluorescence lifetime of the Sn(IV) porphycene complexes indicated by the fluorescence quantum yield and lifetime measurement were observed in the case of the Sn(IV) porphycene ([Sn(IV)(OEPc)Cl(2)], Phi(F) = 0.125, tau(s) = 2681 ps; [Sn(IV)(OEP)Cl(2)], Phi(F) = 0.010, tau(s) = 438 ps; [Sn(IV)(OEHPc)Cl(2)], Phi(F) = 0.027, tau(s) = 733 ps). The triplet state of the Sn(IV) complexes was investigated by transient absorption spectroscopy. It became clear that the triplet lifetime of the Sn(IV) porphycene (tau(T) = 49.9 mus) was longer when compared to those of the Sn(IV) porphyrin (tau(T) = 32.6 mus) and hemiporphycene complexes (tau(T) = 28.3 mus). These porphyrin isomer Sn(IV) complexes showed the high singlet oxygen generating ability, and the photo-oxidation of the 1,5-hydroxynaphthalene mediated by the Sn(IV) porphycene was the most effective among the complexes. This result is due to its more effective light absorption in the visible region and indicated that the porphycene is an excellent candidate as a photosensitizer.

Electron transfer in the supramolecular donor-acceptor dyad of zinc porphycene.

The electron transfer processes of Zn octaethylporphycene (ZnPcn), a structural isomer of Zn octaethylporphyrin, have been investigated mainly using transient absorption spectroscopy. To form a supramolecular donor-acceptor dyad, imide compounds bearing a pyridine group at the N position of the imides have been used as an acceptor. The N atom of the pyridine ring can coordinate to the central Zn ion of ZnPcn. Formation of a supramolecular donor-acceptor dyad, that is, pentacoordinated ZnPcn, was confirmed by steady-state absorption spectroscopy using toluene as a solvent. Charge separation upon excitation of ZnPcn was indicated by efficient fluorescence quenching, especially when pyromellitic diimide was used as the acceptor. Electron transfer processes were confirmed by subpicosecond transient absorption spectroscopy, in which generation of a radical anion of the acceptor and a radical cation of ZnPcn, which was identified by means of gamma-ray radiolysis, was confirmed. It became clear that the charge separation rate was smaller than that of the corresponding supramolecular dyads of Zn tetraphenylporphyrin and Zn octaethylporphyrin despite a similar driving force. This observation indicates a larger internal reorganization energy and a smaller coupling element of the ZnPcn dyad.

Role of Parp-1 in suppressing spontaneous deletion mutation in the liver and brain of mice at adolescence and advanced age.

Poly(ADP-ribose) polymerase-1 knockout (Parp-1(-/-)) mice show increased frequency of spontaneous liver tumors compared to wild-type mice after aging. To understand the impact of Parp-1 deficiency on mutations during aging, in this study, we analyzed spontaneous mutations in Parp-1(-/-) aged mice. Parp-1(-/-) mice showed tendencies of higher mutation frequencies of the red/gam genes at 18 months of age, compared to Parp-1(+/+) mice, in the liver and brain. Complex-type deletions, accompanying small insertion were observed only in Parp-1(-/-) mice in the liver and brain. Further analysis in the liver showed that the frequency of single base deletion mutations at non-repeat or short repeat sequences was 5.8-fold higher in Parp-1(-/-) than in Parp-1(+/+) mice (p<0.05). A 3.2-fold higher tendency of the deletion frequency of two bases or more was observed in Parp-1(-/-) mice compared to Parp-1(+/+) mice (p=0.084). These results support the model that Parp-1 is involved in suppressing imprecise repair of endogenous DNA damage leading to deletion mutation during aging. The mutation frequencies of the gpt gene in the brain were found to be 3-fold lower in Parp-1(-/-) than in Parp-1(+/+) mice at 4 months of age (p<0.01), implying that Parp-1 may be positively involved in imprecise DNA repair in the brain. On the other hand, the frequencies of gpt mutation showed an increase at 18 months of age in the Parp-1(-/-) (p<0.05) but not in Parp-1(+/+) brains, suggesting that Parp-1 deficiency causes an increase of point mutations in the brain by aging.