I-V characteristics of graphene nanoribbon/h-BN heterojunctions and resonant tunneling.

We present the first principle calculations of the electrical properties of graphene sheet/h-BN heterojunction (GS/h-BN) and 11-armchair graphene nanoribbon/h-BN heterojunction (11-AGNR/h-BN), which are carried out using the density functional theory (DFT) method and the non-equilibrium Green's function (NEGF) technique. Since 11-AGNR belongs to the conductive (3n-1)-family of AGNR, both are metallic nanomaterials with two transverse arrays of h-BN, which is a wide-gap semi-conductor. The two h-BN arrays act as double barriers. The transmission functions (TF) and I-[Formula: see text] characteristics of GS/h-BN and 11-AGNR/h-BN are calculated by DFT and NEGF, and they show that quantum double barrier tunneling occurs. The TF becomes very spiky in both materials, and it leads to step-wise I-[Formula: see text] characteristics rather than negative resistance, which is the typical behavior of double barriers in semiconductors. The results of our first principle calculations are also compared with 1D Dirac equation model for the double barrier system. The model explains most of the peaks of the transmission functions nearby the Fermi energy quite well. They are due to quantum tunneling.

Exaggerated arsenic nephrotoxicity in female mice through estrogen-dependent impairments in the autophagic flux.

Gender is one of the essential factors in the development of various diseases and poisoning. Therefore, we herein examined gender differences in sodium arsenite (NaAsO2)-induced acute renal dysfunction. When male and female BALB/c mice were subcutaneously injected with NaAsO2 (12.5mg/kg), serum and urinary markers for proximal tubular injury were significantly higher in female mice than in male ones. NaAsO2-induced histopathological alterations were consistently more evident in females than in males. Ovariectomy, but not orchiectomy significantly attenuated NaAsO2-induced renal injury. These results imply that the hypersusceptibility of female mice is attributed to estrogen signals. NaAsO2 suppressed the autophagic flux in tubular cells through the activation of ERK. Enhancements in the activation of ERK were significantly greater in females than in males, with the eventual accumulation of LC3-II and P62 in the kidneys, implying that the autophagic flux is impaired in females. The IL-6/STAT3 signaling pathway had protective roles in NaAsO2-induced nephrotoxicity through the suppression of ERK activation. Despite the absence of differences in intrarenal IL-6 expression between male and female mice, STAT3 was less activated with enhanced SOCS3 expression in females than in males. An in vitro study using mProx24 cells revealed that the estrogen treatment induced SOCS3 expression, and eventually suppressed the autophagic flux, as evidenced by greater increases in the accumulation of LC3-II and p62 with ERK activation, which was canceled by the knockdown of Socs3. Collectively, these results indicate that estrogen has a negative impact on the development of NaAsO2 nephrotoxicity through its suppression of the autophagic flux.

Immunohistochemical analysis on MMP-2 and MMP-9 for wound age determination.

We performed immunohistochemical study combined with morphometrical analyses in order to examine the expression of matrix metalloproteinase-2 (MMP-2) and MMP-9 using 55 human skin wounds of different ages: group I, 0-3 days (n = 16); II, 4-7 days (n = 11); III, 9-14 days (n = 16); and IV, 17-21 days (n = 12). Immunopositive reactions for MMP-2 were observed in all human skin specimens including uninjured skin as control. The number of MMP-2(+) macrophages was significantly increased in accordance with wound ages. In contrast to MMP-2, no MMP-9(+) signals were detected in uninjured and wound specimens aged less than 1 day. However, the number of MMP-9(+) macrophages profoundly appeared in groups II and III. Morphometrically, in all of wound samples aged 9-12 days, MMP-2(+) cell number was more than 20. On the contrary, most of the remaining samples had <20 positive cells. However, only one sample (a 7-day-old wound) showed 21 positive cells. Thus, with regard to practical applicability with forensic safety, MMP-2(+) macrophages of >20 would indicate a wound age of 7-12 days. Additionally, 10 out of 12 wound specimens aged 9-12 days showed the MMP-2(+) cell number of >25, implying that MMP-2(+) cell number of >25 would indicate the wound age of 9-12 days. On the contrary, all wound samples aged 3-14 days except for only one sample had MMP-9(+) cell number of >30, indicating that MMP-9(+) cell number of >30 would indicate the wound age of 3-14 days. Collectively, MMP-2 seemed to be more distinct marker, compared with MMP-9.

Thromboembolism during hormone therapy in Japanese women.

Japanese women are unaccustomed to taking hormone therapies such as oral contraceptives (OCs) and hormone replacement therapy (HRT); therefore, there are few studies associated with hormone treatment in Japan. This study focused on evaluating thromboembolism during hormone therapy in Japanese women. In February 2002, we mailed questionnaires regarding the monthly average number of patients who had received prescriptions for OCs and HRT, and the incidence of arterial and venous thromboemboli during hormone therapy for the last 10 years. The mailings were sent to hospitals and clinics that are registered as monitoring institutions with the Japan Association of Obstetricians and Gynecologists. Of 1083 institutes, 771 responded (71% response rate). In July 2002, to obtain additional information on hormone therapy, patient history, and outcomes, we sent follow-up questionnaires to 39 institutions that responded as having experienced cases of thromboembolism. Thirty-nine institutions (5.1% of institutions responding to survey) experienced 53 cases of thromboembolism during hormone therapy. The 53 patients included 29 who received OCs (OC patients), 13 who received HRT (HRT patients), and 11 who received other hormone treatment. Among the 29 OC patients, eight had been diagnosed as having arterial thromboembolism (ATE), including two patients with myocardial infarction (MI) and six with ischemic stroke, whereas 20 had venous thromboembolism (VTE), including two with pulmonary embolism (PE) The remaining patient had an unknown thromboembolic event. Of the OC patients, 75.9% had a thromboembolism within the first year, and 58.6% patients were in their 40s. In 13 HRT patients, seven had ATE, including two MI patients and three with ischemic brain stroke, whereas six had VTE, including one PE patient. The duration of HRT varied widely from less than 1 year to more than 3 years; moreover, the HRT type did not affect thromboembolism occurrence. More than 70% of ATE patients and less than one third of VTE patients had to be hospitalized for the treatment of thromboembolism, and more than 75% of VTE patients recovered completely. However, one third of the ATE patients recovered with mild sequelae, one OC patient had severe sequelae due to stroke, and another OC patient died due to an ischemic event. The estimated incidence of thromboembolism in OC patients and HRT patients was 3.6 to 14.4 and 1.7 to 3.4 per 100,000 woman-years, respectively. The risk factors of thromboembolism, which were found consistently in this study, included obesity, smoking, lifestyle, and aging. Approximately 95% of institutions had not experienced thromboembolism in their hormone therapy patients, suggesting the incidence of thromboembolism during hormone therapy might be low. However, according to an analysis of risk factors, screening users of hormone supplements may be essential for providing safe hormone therapy. Moreover, because of the early occurrence of thromboembolism during hormone therapy, especially with OCs, it is important to monitor and instruct patients with caution from immediately after therapy initiation.

Studies on the Purification and Characterization of Human Urinary Plasminogen and Plasmin.

A new method is described for the preparation of highly purified human plasminogen and plasmin with specific activity of 32 CTA units per mg of protein. With this method, the purification of the urinary plasminogen + plasmin antigenic materials from patients with chronic glomerulonephritis, disseminated intravascular coagulation syndrome and severe toxemia of pregnancy was performed, and the resulting highly purified proenzyme and enzyme were analyzed by immunoelectrophoresis, separative agar electrophoresis, gel filtration and SDS-gel electrophoresis.Our findings indicated that urinary plasmin reflects more closely the extent of intraglomerular fibrinolysis, while urinary plasminogen reflects non-selective proteinuria in patients with chronic glomerulonephritis or severe toxemia of pregnancy.