Robustness and resilience of supply chains during the COVID-19 pandemic

Using a unique firm-level data set from Asia, this study examines what determined the robustness and resilience of supply chain links, that is, the ability of maintaining links and recovering disrupted links by substitution, respectively, when firms faced economic shocks due to the spread of the coronavirus disease (COVID-19). We find that a supply chain link was likely to be robust if the link was between a foreign-owned firm and a firm located in the foreign-owned firm's home country, implying that homophily on a certain dimension generates strong ties and thus supply chain robustness. We also find that firms with geographic diversity of customers and suppliers tended to increase their transaction volume with one partner while decreasing the volume with others. This evidence shows that firms with diversified customers and suppliers are resilient, mitigating the damage from supply chain disruption through the substitution of partners. Furthermore, the robustness and resilience of supply chains are found to have led to higher performance.

Preoperative Staging and Surgical Approaches for Sinonasal Inverted Papilloma

Objectives:

We sought to determine the value of preoperative staging by magnetic resonance imaging (MRI) assessment in the surgical management of sinonasal inverted papillomas (IPs).

Methods:

Preoperative MRI staging was used to assess 22 patients with IPs. In addition to the Krouse staging system, T3 cases were categorized as subgroup T3-B if tumors extended into the frontal sinus or the supraorbital recess; otherwise, they were categorized as T3-A. Standard endoscopic sinus surgery (ESS) was the first choice for T1 and T2 cases. Endoscopic approaches, including ESS combined with endoscope-assisted transantral approach and endoscopic medial maxillectomy, were considered in T3-A cases, and external approaches were considered in T3-B cases. Patients were followed for a minimum of 1 year after surgery.

Results:

Preoperative MRI staging and postoperative staging were coincident in 21 of the 22 patients (95%). All 8 T2 cases were treated by an endoscopic approach. Of 10 T3-A cases, 9 (90%) were treated by an endoscopic approach and 1 (residual case) was treated by an external approach. All 3 of the T3-B cases underwent an external approach. One T4 case with malignant transformation underwent an external approach followed by radiotherapy. After a median follow-up period of 22 months, none of the 22 patients had had a recurrence. No major complications were observed after endoscopic approaches, but epiphora or hemorrhage requiring transfusion occurred in 3 of the 5 patients (60%) who underwent external approaches.

Conclusions:

Preoperative staging of IP by MRI is useful for selecting cases that can be managed by endoscopic approaches, resulting in lower rates of tumor recurrence and morbidity.

EGFR inhibitors augment antitumour helper T-cell responses of HER family-specific immunotherapy

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is a major cause of cancer-related morbidity and mortality worldwide. Epidermal growth factor receptor (EGFR)-targeted therapy is an attractive strategy alternative to conventional cancer treatments for HNSCC, but its efficacy remains controversial. T-cell-based immunotherapy has been proposed as a novel therapeutic approach to improve the clinical outcome for HNSCC. In this study, we report human epidermal receptor (HER) family epitopes that induced CD4 T-cell responses to HNSCC. The results provide support for a novel strategy to treat HNSCC by combining EGFR-targeted therapy with T-cell-based immunotherapy.

METHODS

We evaluated the capacity of predicted CD4 T-cell peptide epitopes from EGFR to induce antitumour immune responses in vitro. In addition, EGFR inhibitors were evaluated for their ability to augment tumour MHC class II expression in HNSCC cell lines and subsequently increase T-cell recognition.

RESULTS

Among several predicted peptide epitopes, EGFR875-889 elicited CD4 T-cell responses that were restricted by HLA-DR4, DR15, or DR53 molecules, indicating that the peptide functions as a promiscuous T-cell epitope. The peptide-reactive T cells responded to autologous dendritic cells loaded with EGFR-expressing tumour cell lysates, indicating that these epitopes are naturally processed. In addition, the CD4 T cells were capable of directly recognising and killing HNSCC cells expressing EGFR and the appropriate HLA class II molecule. T cells reactive with the EGFR875-889 epitope could be detected in the blood of HNSCC patients. EGFR875-889-reactive CD4 T cells were also able to recognise several peptide analogues derived from homologous regions of EGFR family members, HER-2, HER-3 and c-MET. Finally, we examined the effects of EGFR tyrosine kinase inhibition or EGFR-blocking antibodies on CD4 T-cell tumour reactivity. Treatment of tumour cells with the EGFR inhibitors enhanced tumour recognition by EGFR875-889-reactive T cells presumably due to the upregulation of HLA-DR expression in the HNSCC cells.

CONCLUSION

We identified novel CD4 T-cell EGFR epitopes and amongst these, EGFR875-889 functions as a promiscuous helper T-cell epitope that can elicit effective antitumour T-cell responses against tumours expressing HER family members and c-MET. These observations should facilitate the translation of T-cell-based immunotherapy into the clinic for the treatment of HNSCC and provide a rational basis for EGFR inhibition, immune-targeted combination therapy.

The field and temperature dependence of the magnetic and structural properties of the shape memory compound Ni(1.84)Mn(1.64)In(0.52)

Magnetization and high resolution neutron powder diffraction measurements have been made on the magnetic shape memory alloy Ni(1.84)Mn(1.64)In(0.52). The compound undergoes a broad structural phase transition, which on heating starts at ∼150 K and finishes at ∼215 K. On cooling there is a ∼20 K hysteresis. The high temperature parent phase is cubic (a = 5.988 Å) with the L2(1) structure in which the excess Mn atoms occupy the vacancies on the Ni and In sites. The magnetic moment is located mainly on the Mn atoms with the same magnitude on both the 4a (Mn) and 4b (In) sites. The low temperature martensite is monoclinic with parameters a = 4.405(2), b = 5.553(2), c = 12.950(2) Å, β = 86.47(10)° and space group P2/m. The magnetic properties of the martensitic phase are complex and indicate metamagnetic behaviour.

Influence of experimental esophageal acidification on sleep bruxism: a randomized trial

The aim of this cross-over, randomized, single-blinded trial was to examine whether intra-esophageal acidification induces sleep bruxism (SB). Polysomnography with electromyogram (EMG) of masseter muscle, audio-video recording, and esophageal pH monitoring were performed in a sleep laboratory. Twelve healthy adult males without SB participated. Intra-esophageal infusions of 5-mL acidic solution (0.1 N HCl) or saline were administered. The frequencies of EMG bursts, rhythmic masticatory muscle activity (RMMA) episodes, grinding noise, and the RMMA/microarousal ratio were significantly higher in the 20-minute period after acidic infusion than after saline infusion. RMMA episodes including SB were induced by esophageal acidification. This trial is registered with the UMIN Clinical Trials Registry, UMIN000002923.

ABBREVIATIONS

ASDA, American Sleep Disorders Association; EMG, electromyogram; GER, gastroesophageal reflux; LES, lower esophageal sphincter; NREM, non-rapid eye movement; REM, rapid eye movement; RMMA, rhythmic masticatory muscle activity; SB, sleep bruxism; SD, standard deviation; UES, upper esophageal sphincter.

Preoperative staging of sinonasal inverted papilloma by magnetic resonance imaging

OBJECTIVES/HYPOTHESIS

Sinonasal inverted papilloma is a rare but locally aggressive benign tumor. Inverted papilloma tends to recur after surgical resection and is occasionally associated with squamous cell carcinoma. Radical en bloc resection by lateral rhinotomy and medial maxillectomy has been recommended for initial management; however, endoscopic sinus surgery is effective in selected cases. To determine adequate surgical approaches, a staging system for inverted papilloma based on extent and location of the tumor has been advocated. The study investigated whether preoperative assessment by magnetic resonance imaging (MRI) accurately predicts the extent of inverted papilloma.

STUDY DESIGN

Magnetic resonance imaging was retrospectively reviewed in 21 cases of inverted papilloma without knowledge of the surgical and pathological findings.

METHODS

Patients were categorized into stages based on MRI findings, according to the staging system proposed by Krouse. The involvement of inverted papilloma in each sinus was also assessed.

RESULTS

Stages graded by MRI were coincident with postoperative staging verified by surgical and pathological findings in 18 of the 21 cases (86%), which included 1 case of stage T1, 3 cases of stage T2, and 14 cases of stage T3. Two cases of stage T2 were judged as T3, and one case of T3 was judged as T2 by MRI. Positive predictive value of MRI diagnosis for tumor involvement was 68% to 89% in each sinus, and negative predictive value was more than 93%.

CONCLUSION

In most cases, MRI assessment of inverted papilloma can accurately predict the extent of tumor involvement. Preoperative staging of inverted papilloma by MRI may be useful for planning an appropriate surgical approach.

Magnetic and structural properties of the magnetic shape memory compound Ni(2)Mn(1.48)Sb(0.52)

Magnetization and high resolution neutron powder diffraction measurements on the magnetic shape memory compound Ni(2)Mn(1.48)Sb(0.52) have confirmed that it is ferromagnetic below 350 K and undergoes a structural phase transition at T(M)≈310 K. The high temperature phase has the cubic L2(1) structure with a = 5.958 Å, with the excess manganese atoms occupying the 4(b) Sb sites. In the cubic phase above ≈310 K the manganese moments are ferromagnetically aligned. The magnetic moment at the 4(a) site is 1.57(12) μ(B) and it is almost zero (0.15(9) μ(B)) at the 4(b) site. The low temperature orthorhombic phase which is only fully established below 50 K has the space group Pmma with a cell related to the cubic one by a Bain transformation a(orth) = (a(cub) + b(cub))/2; b(orth) = c(cub) and c(orth) = (a(cub) - b(cub)). The change in cell volume is ≈2.5%. The spontaneous magnetization of samples cooled in fields less than 0.5 T decreases at temperatures below T(M) and at 2 K the magnetic moment per formula unit in fields up to 5.5 T is 2.01(5) μ(B). Neutron diffraction patterns obtained below ≈132 K gave evidence for a weak incommensurate magnetic modulation with propagation vector (2/3, 1/3, 0).

Cochlear protection from acoustic injury by inhibitors of p38 mitogen-activated protein kinase and sequestosome 1 stress protein

This study evaluated the protective role of p38 mitogen-activated protein kinase (p38 MAPK) inhibitors and sequestosome 1 (Sqstm1/A170/p62), a stress-induced signal modulator, in acoustic injury of the cochlea in mice. Two weeks after the exposure of mice to acoustic stress, threshold shifts of the auditory brainstem response (ABR) from the pre-exposure level and hair cell loss were evaluated. The activation of p38 MAPK was observed in cochlea by immunostaining 4 h after acoustic stress. To examine the role of p38 MAPK in tissue injury, its inhibitors were i.p. injected into male wild-type C57BL mice before the acoustic overexposure. The inhibitors SB202190 and SB203580 but not the inactive analogue SB202474 dose-dependently decreased the auditory threshold shift and outer hair cell loss induced by acoustic overexposure, suggesting the involvement of p38 MAPK in ototoxicity. We found that acoustic overexposure induced the up-regulation of Sqstm1 mRNA expression in the cochlea of wild-type mice and that SQSTM1-deficient mice exhibited an enhanced ABR threshold shift and hair cell loss, suggesting a role of SQSTM1 in the protection of tissue from acoustic stress.

Stress-assisted large magnetic-field-induced strain in single-variant Co-Ni-Ga ferromagnetic shape memory alloy

The magnetic anisotropy and the magnetic-field-induced strain (MFIS) in a single-variant Co(47.5)Ni(22.5)Ga(30.0) ferromagnetic shape memory alloy (FSMA) have been investigated. From the magnetization curves for the single crystal, the hard c-axis was confirmed, and the uniaxial magnetic anisotropy constant K(u) at 300 K was evaluated to be -1.07 × 10(6) erg cm(-3) for the single-variant Co(47.5)Ni(22.5)Ga(30.0) martensite phase. The magnitude of compressive shear stress for the variant rearrangement was estimated to be 6.0-7.5 MPa from the stress-strain curves. An assisted stress τ(assist) of 6.0 MPa was applied before applying a magnetic field, and then a magnetic stress τ(mag) of 0.3 MPa was added. As a result, a large MFIS of about 7.6 % was obtained at room temperature in the martensite phase of the single-variant Co(47.5)Ni(22.5)Ga(30.0).

Magnetic anisotropy of epitaxially grown Co and its alloy thin films

We have performed a systematic study on the correlation between magnetic anisotropy energy (MAE) and crystal structures, such as lattice parameters, stacking fault densities, lattice strain, and so on, for epitaxially grown Co, Co-Pt, and Co-Pd alloy thin films, and have found that the MAE strongly depends on the axial ratio c/a of the hcp crystal lattice. As the c/a of hcp Co decreases down to ∼1.61 which is smaller than 1.622 for bulk Co, the MAE becomes significantly enhanced up to ∼10(6) J m(-3). Similar trends have also been verified for hcp Co-Pt and -Pd. These results, which are qualitatively consistent with the classic single-ion anisotropy model and the recent first principles calculation, suggest a new effective way to control the MAE of magnetic thin films.

Magnetic anisotropy in Ni-Fe-Ga-Co ferromagnetic shape memory alloys in the single-variant state

The effects of the addition of Co on the magnetic anisotropy in Ni(55-x)Fe(18)Ga(27)Co(x) (x = 1-6) single-variant ferromagnetic shape memory alloys have been investigated. By the addition of Co from 1 to 6 at.%, the Curie temperature T(C) is increased from 318 to 405 K, keeping the martensitic transformation temperatures above room temperature. As a result, the value of the uniaxial magnetic anisotropy constant |K(u)| at 300 K increases with increasing x of the Co concentration and the martensite phase of Ni(49)Fe(18)Ga(27)Co(6) exhibits a relatively high value of |K(u)| = 1.15 × 10(5) J m(-3) at 300 K. With increasing Co concentration, on the other hand, the c axis changes from the magnetic easy axis to the hard axis at 4.2 K, that is, the sign of K(u) is reversed from positive to negative between 2 and 3 at.% Co. Furthermore, K(u) in Ni(53)Fe(18)Ga(27)Co(2) is positive below 100 K and negative above 100 K up to T(C), reducing the magnetic anisotropy around 200 K. From the present results, it is evident that the magnetic anisotropy of Ni(55-x)Fe(18)Ga(27)Co(x) (x = 1-6) single-variant ferromagnetic shape memory alloys is very sensitive to Co concentration and also temperature.

Expression of G protein-coupled receptor kinase 4 is associated with breast cancer tumourigenesis

G-protein-coupled receptor kinases (GRKs) comprise a family of seven mammalian serine/threonine protein kinases that phosphorylate and regulate agonist-bound, activated, G-protein-coupled receptors (GPCRs). GRKs and beta-arrestins are key participants in the canonical pathways leading to phosphorylation-dependent GPCR desensitization, endocytosis, intracellular trafficking and resensitization. Here we show that GRK4 isoforms are expressed in human breast cancer but not in normal epithelia. In addition, GRK4-over-expressing cells activated the mitogen-activated protein kinase (MAPK) mediated by ERK 1/2 and JNK phosphorylation in breast cancer-derived cell lines. Furthermore, suppression of beta-arrestins decreased GRK4-stimulated ERK 1/2 or JNK phosphorylations. These data indicate that high-level expression of GRK4 may activate MAPK signalling pathways mediated by beta-arrestins in breast cancer cells, suggesting that GRK4 may be implicated in breast cancer carcinogenesis.

Effects of serine protease inhibitor and prostaglandin I2 on liver transplantation from non-heart-beating rat donors

OBJECTIVES

We sought to preserve the microcirculation as a keystone in liver transplantation from a non-heart-beating donor (NHBD). The purpose of this study was to investigate the cytoprotective effects of a serine protease inhibitor, nafamostat mesilate, and prostaglandin I2 (PGI2) on livers transplanted from NHBDs.

METHODS

Male Wistar rats were used in five groups of nine rats each. In group 1, livers were retrieved from heart-beating donors (HB group); in group 2, livers were retrieved from NHBDs that had experienced agonal apnea (NHB group); in group 3, livers were retrieved in the same manner as in the NHBD group but were pretreated with nafamostat mesilate (NM), 0.2 mg/kg/h, (NM group); in group 4, livers were retrieved in the same manner as in the NHBD group but were pretreated with prostaglandin (PG) I2, 33 ng/kg/h for 30 minutes (PG group); and in group 5, livers were retrieved in the same manner as in the NHBD group but were pretreated with NM plus PG, (NM+PG group). Livers were perfused for 60 minutes with Krebs-Henseleit bicarbonate buffer after 6 hours of cold preservation, after which the perfusate and liver tissue were analyzed in one set of experiments. In another set of experiments, livers retrieved and after 1 hour of cold preservation were transplanted according to the Kamada method.

RESULTS

In the NM+PG group, the values of interleukin-1beta, tumor necrosis factor-alpha, and thromboxane B2 were significantly lower than those in the NHB group. At histologic analysis, sinusoidal endothelial cells were well preserved in the NM+PG group. The number of survivors at 7 days after liver transplantation in the 5 groups were 9, 0, 1, 1, and 3, respectively.

CONCLUSION

The serine protease inhibitor, NM, and PGI2 supported sinusoidal endothelial cells and preserved microcirculation.

Decrease of 4,5,6,7-tetrachlorophthalide in paddy field soil after aerial application

Variation in the fungicide, 4,5,6,7-tetrachlorophthalide (phthalide), in paddy field soil was investigated in order to evaluate its decrease after aerial application by a radio-controlled helicopter. The maximum concentrations of phthalide were 309-320 microg/kg dry, which were 83%-96% of the applied phthalide. The organic carbon normalized soil sorption coefficient (K(oc)) was calculated to be 94-96 mL/g at 1 h after the application. The calculated K(oc) values increased to 620-1,300 mL/g from 1 through 9 days after the application and then 4,700-7,200 mL/g 14 days after the application. The half-life of the phthalide was calculated to be 20-31 days.

Variation of 4,5,6,7-tetrachlorophthalide in water after aerial application to rice cultivation area

Variation in the fungicide, 4,5,6,7-phthalide, in water was investigated in order to evaluate the runoff of the fungicide after aerial application to paddy fields by a radio-controlled helicopter. The survey was conducted for 4 months after the application. The average and maximum concentrations of phthalide were 3.7-4.4 microg/L and 30.5-33.8 microg/L in the paddy fields, 0.37-0.64 microg/L and 2.7-7.5 microg/L in the drainage channels, and 0.18 and 0.83 microg/L in a river, respectively. The runoff ratios of the aerially applied phthalide from the paddy fields into the drainage channels were calculated to be 1.7-2.4%.

Clinical and pathological analysis of recurrent inverted papilloma

OBJECTIVES

We analyzed the clinical characteristics, pathological findings, and treatment outcomes of patients with recurrent sinonasal inverted papilloma (IP).

METHODS

This retrospective study consisted of 13 patients with recurrent IP. Patient data were collected on prior treatment, sites of recurrence, surgical procedures, pathological findings, and postoperative time to recurrence.

RESULTS

Eleven of the 13 patients (85%) had recurrence in the ethmoid sinus, particularly at the lamina papyracea (n = 8; 62%). Inverted papilloma with severe dysplasia (SD) was observed in 4 patients, 3 of whom showed malignant transformation of the recurrent tumor. Craniofacial resection was performed in 2 of the 4 patients, resulting in no further recurrence. However, the tumor was not managed in the remaining 2 patients. In the 9 patients without SD, lateral rhinotomy was performed in 6 patients and endoscopic sinus surgery was selected in 3 patients who had a small tumor without scar formation. No further recurrence was observed in the 9 patients.

CONCLUSIONS

Careful management of IP around the lamina papyracea is essential during initial surgery. Recurrent IP without SD can be successfully managed by lateral rhinotomy in most cases, and by endoscopic sinus surgery in selected cases. However, more aggressive treatment, including craniofacial resection, should be considered in IP with SD, which is associated with a high rate of recurrence and malignant transformation.

Cobalt-base high-temperature alloys

We have identified cobalt-base superalloys showing a high-temperature strength greater than those of conventional nickel-base superalloys. The cobalt-base alloys are strengthened by a ternary compound with the L1(2) structure, gamma' Co3(Al,W), which precipitates in the disordered gamma face-centered cubic cobalt matrix with high coherency and with high melting points. We also identified a ternary compound, gamma' Ir3(Al,W), with the L1(2) structure, which suggests that the Co-Ir-Al-W-base systems with gamma+gamma' (Co,Ir)3(Al,W) structures offer great promise as candidates for next-generation high-temperature materials.

Magnetic-field-induced shape recovery by reverse phase transformation

Large magnetic-field-induced strains have been observed in Heusler alloys with a body-centred cubic ordered structure and have been explained by the rearrangement of martensite structural variants due to an external magnetic field. These materials have attracted considerable attention as potential magnetic actuator materials. Here we report the magnetic-field-induced shape recovery of a compressively deformed NiCoMnIn alloy. Stresses of over 100 MPa are generated in the material on the application of a magnetic field of 70 kOe; such stress levels are approximately 50 times larger than that generated in a previous ferromagnetic shape-memory alloy. We observed 3 per cent deformation and almost full recovery of the original shape of the alloy. We attribute this deformation behaviour to a reverse transformation from the antiferromagnetic (or paramagnetic) martensitic to the ferromagnetic parent phase at 298 K in the Ni45Co5Mn36.7In13.3 single crystal.

The human papillomavirus E6 and E7 inducible oncogene, hWAPL, exhibits potential as a therapeutic target

Here we show that human papillomavirus (HPV) E6 and E7 oncoproteins induce hWAPL expression. In addition, small interfering RNA (siRNA) of hWAPL suppressed the growth of tumours derived from SiHa cells in nude mice. Thus, hWAPL may be one of the effective targets of uterine cervical cancer therapy.

Prevention of critical telomere shortening by oestradiol in human normal hepatic cultured cells and carbon tetrachloride induced rat liver fibrosis

BACKGROUND AND AIM

Significant telomere shortening of hepatocytes is associated with replicative senescence and a non-dividing state in chronic liver disease, resulting in end stage liver failure and/or development of hepatocellular carcinoma. To prevent critical telomere shortening in hepatocytes, we have focused on oestrogen dependent transactivation of the human telomerase reverse transcriptase (hTERT) gene as a form of telomerase therapy in chronic liver disease.

METHODS

We examined expression of hTERT mRNA and its protein, and telomerase activity (TA) in three human normal hepatic cell lines (Hc-cells, h-Nheps, and WRL-68) before and after treatment with 17beta-oestradiol. The effects of exogenous oestradiol administration were examined in a carbon tetrachloride (CCl(4)) induced model of liver fibrosis in rats.

RESULTS

Expression of hTERT mRNA and its protein was upregulated by oestradiol treatment. Telomere length decreased in Hc-cells and h-Nheps with accumulated passages whereas with long term oestradiol exposure it was greater than without oestradiol. The incidence of beta-galactosidase positive cells, indicating a state of senescence, decreased significantly in oestradiol treated cells in comparison with non-treated cells (p<0.05). TA in both male and female rats with CCl(4) induced liver fibrosis was significantly higher with oestradiol administration than without (p<0.05). Long term oestradiol administration markedly rescued the hepatic telomere from extensive shortening in both male and female rats.

CONCLUSION

These results suggest that oestradiol acts as a positive modulator of the hTERT gene in the liver. Oestrogen dependent transactivation of the hTERT gene is a new strategy for slowing the progression of chronic liver disease.

Mucosal sulfhydryl compounds evaluation by in vivo electron spin resonance spectroscopy in mice with experimental colitis

BACKGROUND

Sulfhydryl (SH) compounds are essential in maintaining mucosal integrity in the gastrointestinal tract. A decrease in colonic mucosal SH compounds affects the redox status of the mucosa, resulting in vulnerability to further attacks. Therefore, there is a strong need for in vivo evaluation of SH compounds in the colonic mucosa.

AIMS

The aim of the current study was to establish a method of evaluating levels of SH compounds in the colonic mucosa of live animals before and after induction of colitis.

METHODS

Murine experimental colitis was induced by instillation of trinitrobenzene sulphonic acid (TNBS) dissolved in 50% ethanol into the colon via the anus. For evaluation of mucosal SH compounds in the colon, 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (carbamoyl-PROXYL), a stable nitroxide radical, was instilled into the colonic lumen of live mice and the spin clearance rate was measured by L-band electron spin resonance (ESR) spectroscopy.

RESULTS

Morphological study showed that mucosal damage was severe one or two days after TNBS instillation. The colonic mucosa started to regenerate at four days, and looked normal at seven days, after induction of colitis. The spin clearance rate of carbamoyl-PROXYL decreased significantly at 0.5, 1, 2, and 4 days after induction of colitis compared with mice before TNBS instillation. Surprisingly, although the colonic mucosa looked normal seven days after TNBS administration, the spin clearance rate still remained significantly slow. The spin clearance rate returned to normal 14 days after induction of colitis. The change in in vivo spin clearance rate was consistent with the time dependent change in mucosal reduced glutathione, a major component of SH compounds.

CONCLUSION

The spin clearance rate obtained by L-band ESR spectroscopy in combination with carbamoyl-PROXYL can give an estimate of the level of colonic mucosal SH compounds in live animals and is useful for evaluating the mucosal defence system against oxidative stress.

Dioxin induces a novel nuclear factor, DIF-3, that is implicated in spermatogenesis

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD; dioxin), a member of a class of environmental pollutants represented by polychlorinated dibenzo-p-dioxins and dibenzofurans, is one of the most toxic artificial compounds ever developed. In this study, we identified a novel TCDD target gene, DIF-3 (dioxin inducible factor-3), by cDNA representational difference analysis. DIF-3 protein is a nuclear factor and possesses a zinc-finger motif at its N-terminus. High DIF-3 mRNA expression in the testes was demonstrated by Northern blot analysis and abundant DIF-3 protein was detected during spermatogenesis. Thus, these results suggest that DIF-3 may be a target gene mediating the reproductive toxicity induced by TCDD.

In vivo imaging of increased oxidative stress in the liver by electron spin resonance-computed tomography

The aim of this study was to investigate whether increased hepatic oxidative stress could be visualised in living animals before the onset of obvious liver injury. Acute hepatic injury was induced in mice by priming with heat-killed Corynebacterium parvum followed by injection of a low dose of lipopolysaccharide (LPS). Low frequency band electron spin resonance-computed tomography (ESR-CT) with 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-1-oxyl (carbamoyl-PROXYL) was used to visualize hepatic oxidative stress. Biochemical and histological investigations performed 3 h after injection of LPS revealed no obvious injury to the liver. Conversely, significant hepatic oxidative stress could be detected at this time. Nitroxides such as carbamoyl-PROXYL are rapidly reduced to the corresponding hydroxylamine in vivo. resulting in the disappearance of their ESR signals. The kinetic clearance of carbamoyl-PROXYL after intravenous administration was delayed significantly in mice that had received LPS, due to impairment of the reduction system by hepatic oxidative stress. ESR-CT of the murine abdomen revealed a high intensity area of carbamoyl-PROXYL which consisted mainly of the liver and enlarged spleen. Time-course observations with ESR-CT using carbamoyl-PROXYL showed that the high intensity area in the liver disappeared rapidly due to reduction of carbamoyl-PROXYL. Three hours after LPS injection into the same mouse, ESR-CT images were obtained again by intravenous injection of carbamoyl-PROXYL. The ESR-CT images of the mouse with hepatic oxidative stress clearly showed that the high intensity area of carbamoyl-PROXYL in the liver persisted for a long period of time. This study is the first report to describe the use of in vivo ESR-CT for visualizing the state of increased oxidative stress in the liver before the onset of obvious hepatic injury.

Dioxin suppresses the checkpoint protein, MAD2, by an aryl hydrocarbon receptor-independent pathway

The compound 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been shown recently to be carcinogenic, but little is currently known about the molecular mechanism of TCDD affecting cell proliferation and carcinogenesis. In this report, we demonstrate that TCDD suppresses the expression of the checkpoint protein, Mad2. Suppression of Mad2 was also observed in aryl hydrocarbon receptor-deficient mouse embryonic fibroblasts, suggesting that TCDD suppresses Mad2 by a novel TCDD receptor signaling mechanism. In addition, HeLa cells treated with TCDD failed to arrest in mitosis after nocodazole treatment. The Mad2 protein plays a significant role in accurate chromosome segregation in mitotic cells. Our data suggest that TCDD may increase chromosomal instability through the suppression of Mad2 expression.