Outcome of pregnancies after onset of the neuromyelitis optica spectrum disorder.

BACKGROUND AND PURPOSE: Data on the pregnancy outcome of neuromyelitis optica spectrum disorder (NMOSD) remain limited, especially for woman who had received immunosuppressive treatment before becoming pregnant. The aim was to evaluate the outcome of pregnancy amongst patients with NMOSD who attempted to become pregnant after NMOSD onset and to identify risk factors that predict pregnancy-related attack. METHODS: Medical records from 29 patients who attempted to become pregnant after NMOSD onset were retrospectively evaluated and the patients were interviewed for pregnancy outcomes. Pregnancy-related attack was defined as an attack that occurred during pregnancy or within 1 year of delivery. RESULTS: Amongst the 29 patients, 26 had 33 pregnancies after NMOSD symptom onset. The 33 pregnancies after NMOSD onset resulted in 24 live births (healthy neonates except one with low birth weight), six miscarriages and three elective abortions. Pregnancy-related attack occurred in nine (75%) of 12 pregnancies before initiation of immunosuppressive therapy, but in only five (24%) of 21 pregnancies after initiation of immunosuppressive therapy (P = 0.009). Multivariable analysis indicated that pregnancy-related attack was negatively associated with pregnancy after initiation of rituximab (odds ratio 0.048, 95% confidence interval 0.004-0.546). CONCLUSION: Successful pregnancy without maternal and neonatal complications may be feasible in patients with NMOSD. Rituximab treatment before pregnancy might help to prevent pregnancy-related attack in patients with NMOSD.

Diffusion tensor imaging of normal-appearing white matter in patients with neuromyelitis optica spectrum disorder and multiple sclerosis.

BACKGROUND AND PURPOSE: The occult changes in normal-appearing white matter (NAWM) were investigated and compared amongst patients with neuromyelitis optica spectrum disorder (NMOSD), patients with multiple sclerosis (MS) and healthy controls (HCs) by applying tract-based spatial statistics to diffusion tensor imaging (DTI) data. METHODS: Diffusion tensor imaging was performed with a 3-T scanner in 93 patients with NMOSD, 53 patients with MS and 43 HCs. Voxel-wise statistical analyses of the DTI data were performed using tract-based spatial statistics. RESULTS: Compared to HCs, patients with NMOSD had significantly lower mean global fractional anisotropy, higher mean diffusivity and radial diffusivity, and no significant differences in axial diffusivity in their NAWM. Patients with MS demonstrated significantly lower mean global fractional anisotropy and higher mean diffusivity, axial diffusivity and radial diffusivity in the NAWM than did patients with NMOSD and HCs. Compared to patients with NMOSD, patients with MS had NAWM damage that was more extensive, particularly in the inferior cerebellar peduncle, external capsule, cingulum, superior fronto-occipital fasciculus and uncinate fasciculus. CONCLUSIONS: Using DTI, widespread occult damage was demonstrated in the NAWM of patients with NMOSD. However, the NAWM was less affected in patients with NMOSD than it was in patients with MS; specifically, the axonal injuries and diffusion abnormalities in the association fibers were more severe in patients with MS than they were in patients with NMOSD.

Normal-appearing white matter demyelination in neuromyelitis optica spectrum disorder.

BACKGROUND AND PURPOSE: Increasing evidence suggests the presence of demyelination in the normal-appearing white matter (NAWM) of patients with neuromyelitis optica spectrum disorder (NMOSD). The objective was to determine the presence of subclinical demyelination in the NAWM of patients with NMOSD using myelin water imaging (MWI). METHODS: Whole brain and regions-of-interest (ROIs) analyses, including the centrum semiovale, corona radiata, genu and splenium of the corpus callosum, and optic radiation, were conducted in the NAWM of 28 NMOSD patients and 18 healthy controls (HCs) using two MWI modalities: conventional MWI and direct visualization of short transverse relaxation time component (ViSTa) MWI. RESULTS: Conventional myelin water fractions (MWFs) of the global NAWM and three ROIs (centrum semiovale, corona radiata, and genu of the corpus callosum) were slightly lower in NMOSD patients than in HCs, although not statistically significant. On the other hand, ViSTa MWF values of the global NAWM and all ROIs except the genu of the corpus callosum were significantly lower in NMOSD patients relative to HCs. In particular, the MWF in the optic radiation was significantly reduced in NMOSD patients relative to HCs in both MWI methods, even in patients who had no brain involvement. Additionally, patients with optic neuritis showed lower MWF than patients without optic neuritis and a negative correlation was identified between the MWF of the optic radiation and visual functional system score. CONCLUSIONS: This study identified the presence of widespread demyelination in the NAWM of NMOSD patients and highlighted the optic radiation as a site of marked demyelination.

Deep gray matter atrophy in neuromyelitis optica spectrum disorder and multiple sclerosis.

BACKGROUND AND PURPOSE: We investigated changes in deep gray matter (DGM) volume and its relationship to cognition and clinical factors in a large cohort of patients with neuromyelitis optica spectrum disorder (NMOSD) and compared them with results from multiple sclerosis (MS). METHODS: Brain magnetic resonance imaging (3 Tesla) and clinical data from 91 patients with NMOSD, 52 patients with MS and 44 healthy controls (HCs) were prospectively evaluated. Differences in DGM volumes were compared among groups. The relationships between DGM atrophy and clinical variables were also analysed. RESULTS: Patients with NMOSD exhibited significantly reduced thalamic volumes compared with HCs (P = 0.029), although this atrophy was less severe than that seen in patients with MS (P < 0.001). DGM atrophy was restricted to the thalamus in NMOSD, but it was broadly distributed in MS. Patients with NMOSD with cognitive impairment (CI) exhibited more severe thalamic atrophy than those with cognitive preservation (P = 0.017) and HCs (P = 0.003), whereas patients with MS with CI revealed DGM atrophy across the entire structure, with the exception of the bilateral pallidum, left hippocampus and amygdala, relative to HCs. The Expanded Disability Status Scale score was correlated with thalamic atrophy in both NMOSD and MS. Patients with NMOSD with brain lesions demonstrated more severe thalamic atrophy than did those without brain lesions and HCs (P < 0.001). CONCLUSIONS: The DGM atrophy was less severe and more selectively distributed in NMOSD than in MS. Thalamic atrophy was associated with clinical disability, including CI, in both NMOSD and MS.

Widespread cortical thinning in patients with neuromyelitis optica spectrum disorder.

BACKGROUND AND PURPOSE: Studies on cortical involvement and its relationship with cognitive function in patients with neuromyelitis optica spectrum disorder (NMOSD) remain scarce. The objective of this study was to compare cortical thickness on magnetic resonance imaging (MRI) between patients with NMOSD and multiple sclerosis (MS) and to investigate its relationship with clinical features and cognitive function. METHODS: This observational clinical imaging study of 91 patients with NMOSD, 52 patients with MS and 44 healthy controls was conducted from 1 December 2013 to 30 April 2015 at the institutional referral center. Three tesla MRI of the brain and neuropsychological tests were performed. Cortical thickness was measured using three-dimensional surface-based analysis. RESULTS: Both sets of patients exhibited cortical thinning throughout the entire brain cortex. Patients with MS showed a significantly greater reduction in cortical thickness over broad regions of the bilateral frontal and parieto-temporal cortices and the left precuneus compared to those with NMOSD. Memory functions in patients with MS were correlated with broad regional cortical thinning, whereas no significant associations were observed between cortical thickness and cognitive function in patients with NMOSD. CONCLUSIONS: Widespread cortical thinning was observed in patients with NMOSD and MS, but the extent of cortical thinning was greater in patients with MS. The more severe cortical atrophy may contribute to memory impairment in patients with MS but not in those with NMOSD. These results provide in vivo evidence that the severity and clinical relevance of cortical thinning differ between NMOSD and MS.

Epigenetic modification of Nrf2 in 5-fluorouracil-resistant colon cancer cells: involvement of TET-dependent DNA demethylation.

5-Fluorouracil (5-FU) is a widely used anticancer drug for the treatment of colorectal cancer (CRC). However, resistance to 5-FU often prevents the success of chemotherapy. Nuclear factor-erythroid 2-related factor 2 (Nrf2) is a transcriptional regulator and a possible target to overcome 5-FU resistance. The present study examined epigenetic changes associated with Nrf2 induction in a human CRC cell line (SNUC5) resistant to 5-FU (SNUC5/5-FUR). Nrf2 expression, nuclear translocation, and binding to promoter were higher in SNUC5/5-FUR cells than in SNUC5 cells. The activated Nrf2 in SNUC5/5-FUR cells led to an increase in the protein expression and activity of heme oxygenase-1 (HO-1), an Nrf2-regulated gene. SNUC5/5-FUR cells produced a larger amount of reactive oxygen species (ROS) than SNUC5 cells. The siRNA- or shRNA-mediated knockdown of Nrf2 or HO-1 significantly suppressed cancer cell viability and tumor growth in vitro and in vivo, resulting in enhanced 5-FU sensitivity. Methylation-specific (MS) or real-time quantitative MS-PCR data showed hypomethylation of the Nrf2 promoter CpG islands in SNUC5/5-FUR cells compared with SNUC5 cells. Expression of the DNA demethylase ten-eleven translocation (TET) was upregulated in SNUC5/5-FUR cells. ROS generated by 5-FU upregulated TET1 expression and function, whereas antioxidant had the opposite effect. These results suggested that the mechanism underlying the acquisition of 5-FU resistance in CRC involves the upregulation of Nrf2 and HO-1 expression via epigenetic modifications of DNA demethylation.

A ginseng metabolite, compound K, induces autophagy and apoptosis via generation of reactive oxygen species and activation of JNK in human colon cancer cells.

Compound K (20-O-(ß-D-glucopyranosyl)-20(S)-protopanaxadiol) is an active metabolite of ginsenosides and induces apoptosis in various types of cancer cells. This study investigated the role of autophagy in compound K-induced cell death of human HCT-116 colon cancer cells. Compound K activated an autophagy pathway characterized by the accumulation of vesicles, the increased positive acridine orange-stained cells, the accumulation of LC3-II, and the elevation of autophagic flux. Whereas blockade of compound K-induced autophagy by 3-methyladenein and bafilomycin A1 significantly increased cell viability. In addition, compound K augmented the time-dependent expression of the autophagy-related proteins Atg5, Atg6, and Atg7. However, knockdown of Atg5, Atg6, and Atg7 markedly inhibited the detrimental impact of compound K on LC3-II accumulation and cell vitality. Compound K-provoked autophagy was also linked to the generation of intracellular reactive oxygen species (ROS); both of these processes were mitigated by the pre-treatment of cells with the antioxidant N-acetylcysteine. Moreover, compound K activated the c-Jun NH2-terminal kinase (JNK) signaling pathway, whereas downregulation of JNK by its specific inhibitor SP600125 or by small interfering RNA against JNK attenuated autophagy-mediated cell death in response to compound K. Compound K also provoked apoptosis, as evidenced by an increased number of apoptotic bodies and sub-G1 hypodiploid cells, enhanced activation of caspase-3 and caspase-9, and modulation of Bcl-2 and Bcl-2-associated X protein expression. Notably, compound K-stimulated autophagy as well as apoptosis was induced by disrupting the interaction between Atg6 and Bcl-2. Taken together, these results indicate that the induction of autophagy and apoptosis by compound K is mediated through ROS generation and JNK activation in human colon cancer cells.

The critical role of catalase in prooxidant and antioxidant function of p53.

The tumor suppressor p53 is an important regulator of intracellular reactive oxygen species (ROS) levels, although downstream mediators of p53 remain to be elucidated. Here, we show that p53 and its downstream targets, p53-inducible ribonucleotide reductase (p53R2) and p53-inducible gene 3 (PIG3), physically and functionally interact with catalase for efficient regulation of intracellular ROS, depending on stress intensity. Under physiological conditions, the antioxidant functions of p53 are mediated by p53R2, which maintains increased catalase activity and thereby protects against endogenous ROS. After genotoxic stress, high levels of p53 and PIG3 cooperate to inhibit catalase activity, leading to a shift in the oxidant/antioxidant balance toward an oxidative status, which could augment apoptotic cell death. These results highlight the essential role of catalase in p53-mediated ROS regulation and suggest that the p53/p53R2-catalase and p53/PIG3-catalase pathways are critically involved in intracellular ROS regulation under physiological conditions and during the response to DNA damage, respectively.

Black Scab of Jojoba (Simmondsia chinensis) in Australia Caused by a Putative New Pathotype of Elsinoë australis.

A new disease of jojoba in Australia is described. We have demonstrated that this disease is caused by Elsinoë australis, a pathogen which is normally associated with citrus. This pathogen has not been found previously in Australia on citrus or any other crop. The fungus causes a scab on leaves and stems of jojoba and is widely distributed in eastern Australia. Although molecular analysis of the pathogen indicates that it is closely related to the natsudaidai and the sweet orange pathotypes of E. australis, glasshouse and laboratory experiments demonstrate that it is not pathogenic to a range of citrus cultivars grown in Australia. The data indicate that the isolates from jojoba represent a new pathotype of E. australis.

The p53-inducible gene 3 (PIG3) contributes to early cellular response to DNA damage.

The p53-inducible gene 3 (PIG3) is originally isolated as a p53 downstream target gene, but its function remains unknown. Here, we report a role of PIG3 in the activation of DNA damage checkpoints, after UV irradiation or radiomimetic drug neocarzinostatin (NCS). We show that depletion of endogenous PIG3 sensitizes cells to DNA damage agents, and impaired DNA repair. PIG3 depletion also allows for UV- and NCS-resistant DNA synthesis and permits cells to progress into mitosis, indicating that PIG3 knockdown can suppress intra-S phase and G2/M checkpoints. PIG3-depleted cells show reduced Chk1 and Chk2 phosphorylation after DNA damage, which may directly contribute to checkpoint bypass. PIG3 exhibited diffuse nuclear staining in the majority of untreated cells and forms discrete nuclear foci in response to DNA damage. PIG3 colocalizes with gamma-H2AX and 53BP1 to sites of DNA damage after DNA damage, and binds to a gamma-H2AX. Notably, PIG3 depletion decreases the efficient induction and maintenance of H2AX phosphorylation after DNA damage. Moreover, PIG3 contributes to the recruitment of 53BP1, Mre11, Rad50 and Nbs1 to the sites of DNA break lesions in response to DNA damage. Our combined results suggest that PIG3 is a critical component of the DNA damage response pathway and has a direct role in the transmission of the DNA damage signal from damaged DNA to the intra-S and G2/M checkpoint machinery in human cells.

Pathotypes and genetic relationship of worldwide collections of Elsinoë spp. causing scab diseases of citrus.

Two scab diseases are recognized currently on citrus: citrus scab, caused by Elsinoë fawcettii, and sweet orange scab, caused by E. australis. Because the two species cannot be reliably distinguished by morphological or cultural characteristics, host range and molecular methods must be used to identify isolates. Four pathotypes of E. fawcettii and two of E. australis have been described to date based on host range. The host specificity and genetic relationships among 76 isolates from Argentina, Australia, Brazil, Korea, New Zealand, and the United States were investigated. Based on pathogenicity tests on eight differential hosts, 61 isolates were identified as E. fawcettii and 15 as E. australis. Of 61 isolates of E. fawcettii, 24 isolates were identified as the Florida broad host range (FBHR) pathotype, 7 as the Florida narrow host range (FNHR) pathotype, 10 as the Tryon's pathotype, and 3 as the "Lemon" pathotype. Two new pathotypes, the "Jingeul" and the satsuma, rough lemon, grape-fruit, clementine (SRGC), are described, and four isolates did not fit into any of the known pathotypes of E. fawcettii. Of the 15 isolates of E. australis from Argentina and Brazil, 9 belonged to the sweet orange pathotype and 6 from Korea to the natsudaidai pathotype. E. fawcettii and E. australis were clearly distinguishable among groups by random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR) assays and the E. fawcettii group was divided into three subgroups, A-1, A-2, and A-3. The A-1 group was composed of the FBHR, FNHR, and SRGC pathotypes; some Lemon pathotypes; and the uncertain isolates. The A-2 subgroup included all of the Tryon's pathotype isolates and one of the three Lemon pathotype isolates and the A-3 group contained the Jingeul pathotype isolates. E. australis was differentiated into two groups: B-1, the natsudaidai pathotype isolates, and B-2, the sweet orange pathotype isolates. Isolates of E. fawcettii and E. australis were clearly distinguishable by sequence analysis of the internal transcribed spacer (ITS) region and the translation elongation factor 1 alpha (TEF) gene. There were also fixed nucleotide differences in the ITS and TEF genes that distinguished subgroups separated by RAPD-PCR within species. We confirmed two species of Elsinoë, two pathotypes of E. australis, and at least six pathotypes of E. fawcettii and described their distribution in the countries included in this study.

Ribonucleotide reductase small subunit p53R2 suppresses MEK-ERK activity by binding to ERK kinase 2.

The p53-dependent RR small subunit (p53R2) protein, a newly identified member of the ribonucleotide reductase family, plays a key role in the p53-dependent cellular response to DNA. Several recent studies have suggested that p53R2 also plays an important role in suppressing the invasive potential of human cancer cells. However, the cellular mechanism that regulates invasiveness remains largely unknown. In this study, we show that p53R2 interacts with MEK2 (extracellular signal-regulated kinase (ERK) kinase 2-mitogen-activated protein kinase (MAPK) kinase 2), the molecule immediately upstream of ERK in the Ras-Raf-MAPK signaling cascade. In co-immunoprecipitation and immunofluorescence analyses, we found that p53R2 and MEK2 interact physically in cultured mammalian cells, and that the p53R2 segment comprising amino acids 161-206 is critical for this interaction. Moreover, serum-induced phosphorylation of MEK1/2 and ERK1/2 was greatly augmented in human cancer cells expressing small-interfering RNA against p53R2. On the other hand, phosphorylation of MEK1/2 and ERK1/2 in human cancer cells was markedly attenuated by overexpression of p53R2. Furthermore, MEK2 was required for p53R2 knockdown-induced enhancement of the invasive ability and anchorage-independent growth of human lung cancer H1299 cells. Taken together, these findings show that p53R2 negatively modulates serum-induced MEK-ERK activity and inhibits the MEK-ERK-mediated malignancy potential of human cancer cells.

Development of PCR Assays for the Identification of Species and Pathotypes of Elsinoë Causing Scab on Citrus.

Two scab pathogens of citrus, Elsinoë fawcettii and E. australis, cause citrus scab and sweet orange scab, respectively, and pathotypes of each species have been described. The two species cannot be readily distinguished by morphological or cultural characteristics and can be distinguished only by host range and the sequence of the internal transcribed spacer (ITS) region. In this study, random amplified polymorphic DNA (RAPD) assays clearly distinguished E. fawcettii and E. australis, and the sweet orange and natsudaidai pathotypes within E. australis also could be differentiated. We developed specific primer sets, Efaw-1 for E. fawcettii; Eaut-1, Eaut-2, Eaut-3, and Eaut-4 for E. australis; and EaNat-1 and EaNat-2 for the natsudaidai pathotype within E. australis using RAPD products unique to each species or pathotype. Other primer sets, Efaw-2 and Eaut-5, which were specific for E. fawcettii and E. australis, respectively, were designed from previously determined ITS sequences. The Efaw-1 and Efaw-2 primer sets successfully identified E. fawcettii isolates from Korea, Australia, and the United States (Florida) and the Eaut-1 to Eaut-5 primer sets identified both the sweet orange pathotype isolates of E. australis from Argentina and the natsudaidai pathotype isolates from Korea. The EaNat-1 and EaNat-2 primer sets were specific for isolates of the natsudaidai pathotype. The Efaw-1 and Efaw-2 primer sets successfully detected E. fawcettii from lesions on diseased leaves and fruit from Korea and primer pairs Eaut-1, Eaut-2, Eaut-3, Eaut-4, and Eaut-5 detected E. australis from lesions on sweet orange fruit from Brazil.

Apoptosis induction by 4beta-acetoxyscirpendiol from Paecilomyces tenuipes in human leukaemia cell lines.

The carpophores of Paecilomyces tenuipes are known in the Orient for their strong antitumor activity. In continuation of our study on acetoxyscirpendiol (ASD, 4beta-acetoxyscirpene-3alpha,15-diol) as a cytotoxic component from this fungus, we report particularly on the mode of action of ASD in inducing apoptosis in human MOLT-4, THP-1 and Jurkat T cell leukaemia in vitro. The antiproliferative effects of ASD seem attributable to its induction of apoptosis in the cells, as it blocked the cell cycle, induced hypodiploidity and bound annexin V and also cleaved poly-(ADP-ribose) polymerase (PARP) in these cell lines. The 50% inhibitory concentrations (IC50) of ASD on MOLT-4, THP-1 and Jurkat T cells were found to be 60, 85 and 60 ng/ml, respectively. ASD arrested the cell cycle at the G1/S transition and showed hypodiploidity due to the accumulation of sub-G0 population. Annexin V binding was increased in the presence of ASD in the MOLT-4 cell line in a time-dependent manner. ASD and three of its derivatives also induced cleavage of PARP in both MOLT-4 and Jurkat T cell lines. From these data, it is suggested that ASD exerts its cytotoxic activity by inducing apoptosis in leukaemia cell lines in vitro.

Cytotoxic activities of acetoxyscirpenediol and ergosterol peroxide from Paecilomyces tenuipes.

Paecilomyces tenuipes is one of the famous Chinese medicinal entomopathogenic fungi that parasites in the lavae of silkworm. Two cytotoxic components were isolated from methanolic extract of the carpophores of this fungus that was cultivated artificially. Spectral analyses of the cytotoxic components showed that they were known ergosterol peroxide (5alpha,8alpha-epidioxy-24(R)-methylcholesta-6,22-dien-3beta-ol) and acetoxyscirpenediol (4beta-acetoxyscirpene-3alpha,15-diol) that were isolated for the first time from this fungus. The 50% inhibitory concentrations (IC50) of ergosterol peroxide against human gastric tumor cell line (SNU-1), human hepatoma cell line (SNU-354), human colorectal tumor cell line (SNU-C4) and murine sarcoma-180 were 18.7, 158.2, 84.6 and 74.1 microM, respectively. The IC50 values of acetoxyscirpenediol against SNU-1, SNU-C4, SNU-354 and sarcoma-180 were 1.2,4.0, 2.2 and 1.9 microM, respectively. Cytotoxic activities of acetoxyscirpenediol were about 4.0-6.6 times stronger than those of cisplatin which is currently used clinically for cancer patients.

Pathological Characterization and Molecular Analysis of Elsinoe Isolates Causing Scab Diseases of Citrus in Jeju Island in Korea.

Two scab diseases are recognized currently on citrus: (i) citrus scab caused by Elsinoe fawcettii, which has several pathotypes; and (ii) sweet orange scab caused by E. australis. Pathogenicity and cultural characteristics among 36 isolates collected from Jeju Island were investigated. Of 30 isolates from satsuma mandarin, yuzu, and kinkoji, all were E. fawcettii; 27 were similar to the Florida broad host range pathotype and 3 were similar to the Florida narrow host range pathotype by inoculation of differential hosts. Six isolates from natsudaidai were nonpathogenic to satsuma mandarin, rough lemon, sour orange, grapefruit, cleopatra mandarin, and natsudaidai leaves, and were only pathogenic to natsudaidai fruit. Isolates from natsudaidai usually produced unique tomentose colonies on potato dextrose agar compared with isolates from other citrus species. The colonies were relatively fast growing, radially sulcate, larger, and more expansive than the gummy, mucoid colonies of other isolates. Isolates from Florida, Australia, Argentina, and Jeju Island (Korea) were genetically differentiated using random amplified polymorphic DNA markers. E. fawcettii from Korea, Florida, and Australia, E. australis from Argentina, and natsudaidai isolates clustered closely within groups, but were clearly distinguishable among groups.

Modulation of the antiproliferative activity of anticancer drugs in hematopoietic tumor cell lines by the poly(ADP-ribose) polymerase inhibitor 6(5H)-phenanthridinone.

Poly (ADP-ribose) polymerase (PARP) is involved in the cellular responses to genotoxic damage and its inhibition has been proposed as potentiating anticancer drug activity. Here, we evaluated the ability of the PARP inhibitor, 6(5H)-phenanthridinone, to modulate the antiproliferative activity of bleomycin, carmustin and doxorubicin in a murine (RDM4) and a human (U937) lymphoma cell lines. 6(5H)-phenanthridinone was shown to suppress PARP activity with the same potency in both cell lines. At 25 microM, this compound potentiated the activity of carmustin in RDM4 but not in U937 cells. In contrast, 6(5H)-phenanthridinone failed to affect the doxorubicin toxicity in murine lymphoma cells, whereas it prevented the cytotoxicity of this drug in the human cell line. Altogether, these findings indicated that 6(5H)-phenanthridinone modulates the cytotoxicity of anticancer agents differently according to the cell type and the drug. Therefore, this PARP inhibitor could be considered as the prototype of a new class of adjuncts in cancer chemotherapy.

Leukemic cell line, KG-1 has a functional loss of hOGG1 enzyme due to a point mutation and 8-hydroxydeoxyguanosine can kill KG-1.

We tested the cytotoxic action of 8-hydroxyguanine (8ohG) by observing the viability of several leukemic cell lines (KG-1, U937, Jurkat and K 562) in the presence of 8-hydroxydeoxyguanosine (8ohdG), a nucleoside of 8ohG. It was found that 8ohdG showed cytotoxic action only to KG-1 and that only KG-1 showed a homozygous arginine 209 to glutamine mutation in the hOGG1 gene with an almost negligible hOGG1 enzyme activity. Possibly, the selective cytotoxicity in 8ohdG to KG-1 may be due to its low capacity to cope with an increase in the 8ohG level in DNA resulting from the incorporation of 8ohdG present in the culture media. The mutational impairment of hOGG1 in KG-1 is the first report in leukemic cell lines. Using KG-1 with impaired hOGG1, we demonstrated cytotoxicity of 8ohdG probably due to its incorporation into cellular DNA. This new property of KG-1 may allow it to serve as an useful tool for studies of OGG1, oxidative DNA damage and the cytotoxic action of 8ohG. Oncogene (2000) 19, 4476 - 4479.

An efficient stereoselective synthesis of [3S(1S,9S)]-3-[[[9-(benzoylamino) octahydro-6,10-dioxo-6H-pyridazino-(1,2-a)(1,2)-diazepin-1-yl]-carbonyl ]amino]-4-oxobutanoic acid, an interleukin converting enzyme (ICE) inhibitor.

The title compound 1 is a potent interleukin-1beta-converting enzyme (ICE) inhibitor. Recently, an efficient chiral synthesis of compound 1 has been accomplished in our labs. The overall yield of this 18-step stereoselective synthesis was 9.8%.

Reduction of radiation-induced chromosome aberration and apoptosis by dithiothreitol.

We have examined in vitro and in vivo radioprotective effects of a well-known thiol-containing compound, dithiothreitol (DTT). The treatment of both 0.5 and 1 mM of DTT significantly increased clonogenic survival of gamma-ray irradiated Chinese hamster (V79-4) cells. In order to investigate the possible radioprotective mechanism of DTT, we measured gamma-ray induced chromosome aberration by micronucleus assay. In the presence of 0.5 mM or 1 mM DTT, the frequencies of micronuclei were greatly reduced in all dose range examined (1.5-8 Gy). Slightly higher reduction in micronucleus formation was observed in 1 mM DTT-treated cells than in 0.5 mM DTT-treated cells. In addition, incubation with both 0.5 and 1 mM of DTT prior to gamma-ray irradiation reduced nucleosomal DNA fragmentation at about same extent, this result suggests that treatment of DTT at concentrations of 0.5 and 1 mM reduced radiation-induced apoptosis. In vivo experiments, we also observed that DTT treatment reduced the incidence of apoptotic cells in mouse small intestine crypts. In irradiated control group 4.4 +/- 0.5 apoptotic cells per crypt were observed. In DTT-administered and irradiated mice, only 2.1 +/- 0.4 apoptotic cells per crypt was observed. In vitro and in vivo data obtained in this study showed that DTT reduced radiation-induced damages and it seems that the possible radioprotective mechanisms of action of DTT are prevention of chromosome aberration.