Double epitaxial silicon avalanche photodiodes for optical-fibre communications

A new type of planar silicon avalanche photodiodes have been fabricated with a high-low impurity profile with a wide avalanche region by double epitaxy. The a.p.d. characteristics of low noise, high speed, high quantum efficiency and relatively low operating voltage make them particularly suitable for optical-fibre communication systems.     

Interphase and metaphase detection of the breakpoint of 14q32 translocations in B-cell malignancies by double-color fluorescence in situ hybridization

The breakpoint of 14q32 translocations found in B-cell malignancies was delineated specifically in both metaphase spreads and interphase nuclei by double-color fluorescence in situ hybridization (FISH) using bacteriophage clones containing the human immunoglobulin gamma chain gene locus (Ig gamma) and a cosmid clone, CY24-68, containing VH segments. CY24-68 is more telomeric than Ig gamma, separated by approximately 1 megabase (Mb). FISH studies were performed on four patients with non-Hodgkin's lymphoma (NHL), one with acute lymphoblastic leukemia (ALL), one with plasma cell leukemia (PCL), and three cell lines. In each patient with t(8;14), t(14;18), and t(3;14), the signal of Ig gamma gene was observed on der(14) and that of CY24-68 at respective partner sites of these translocations, 8q24.1, 18q21.3, and 3q27. Interphase nuclei with a signal of Ig gamma clearly separated from that of CY24-68 were more frequently encountered in all of the patients (45% to 74%) than those in normal controls (4% to 5%). Even in cases where only interphase nuclei were available for FISH studies, 14q32 translocations are detected as shown in two patients each with NHL and t(11;14)-carrying PCL. In two cell lines, HS-1 derived from ALL carrying t(8;14) and FR4 derived from a plasmacytoma carrying a complex form of t(8;14), the signal of Ig gamma was observed at the breakpoint region 8q24.1 of the der(8) in addition to the der(14), indicating that translocation event occurred within the Ig gamma locus. Intense Ig gamma signal was found at the breakpoint region on the der(14)t(11;14) in HBL-2 derived from NHL, indicating amplification of the Ig gamma gene, and presumably the resultant chimeric DNA between Ig gamma and DNA sequences at 11q13. The present approach allowed us to unequivocally detect tumor-specific breakpoints of 14q32 translocations. Furthermore, interphase FISH provides a rapid diagnostic procedure to detect 14q32 translocations in B-cell malignancies.     

Differentiation and transforming growth factor-beta receptor down-regulation by collagen-alpha2beta1 integrin interaction is mediated by focal adhesion kinase and its downstream signals in murine osteoblastic cells

Interaction of type I collagen (COL(I)) with alpha2beta1 integrin causes differentiation and transforming growth factor (TGF)-beta receptor down-regulation in osteoblastic cells (Takeuchi, Y., Nakayama, K., and Matsumoto, T. (1996) J. Biol. Chem. 271, 3938-3644). The TGF-beta receptor down-regulation enables cells to escape from the inhibition of differentiation by TGF-beta. To clarify how the cell-matrix interaction regulates these phenotypic changes, signaling pathways were examined in murine MC3T3-E1 cells. Attachment of cells to COL(I) stimulated tyrosine phosphorylation of focal adhesion kinase (FAK) and extracellular signal-regulated kinase (ERK), a mitogen-activated protein kinase (MAPK), and enhanced MAPK activity. Inhibition of tyrosine kinase by herbimycin A, destruction of focal adhesion by cytochalasin D, or overexpression of antisense FAK mRNA prevented the activation of ERK/MAPK and the increase in alkaline phosphatase (ALP) activity. Transient expression of a MAPK-specific phosphatase, CL100, also suppressed the elevation of ALP activity. In addition, introduction of a constitutively active MAPK kinase enhanced ALP activity in the absence of collagen production. TGF-beta receptor down-regulation was abrogated by treatments that inactivate FAK, whereas the expression of CL100 had no effect. These results demonstrate that COL(I)-alpha2beta1 integrin interaction facilitates differentiation and down-regulates TGF-beta receptors via the activation of FAK and its diverse downstream signals. These signaling pathways may play an important role in the sequential differentiation of osteoblasts during bone formation.     

Neutronics and burnup analysis of an accelerator-based tru-nitride fuel transmutation system with the ATRAS code

The neutronics and burnup analyses of an accelerator-based transmutation system with tungsten target and TRU-nitride fuel were performed with a newly developed code system named ATRAS (Accelerator-based Transmutation Reactor Analysis System). The ATRAS code is an integrated code system which can perform the hadronic cascade process above 20 MeV and neutron transport and core burnup process below 20 MeV with the spallation neutron source.

The specifications of the transmutation system are investigated. The core consists of the central spallation target region and the surrounding TRU-mononitride fuel region. The core is driven by protons at an energy of 1.0 GeV. This system was also proposed as a benchmark problem in the “OECD NEA/NSC Benchmark on Physics aspects of Different Transmutation Concepts”.

According to the calculation results by the ATRAS code, higher power density and transmutation rate were achieved with nitride fuel, and the neutron spectrum was slightly harder than that of the metallic fuel system. The burnup calculation for thermal power 800 MW was also performed with the ATRAS code. It is shown that about 300 kg of TRU are transmuted annually.     

Evi-1 raises AP-1 activity and stimulates c-fos promoter transactivation with dependence on the second zinc finger domain

Evi-1 is a gene, encoding a zinc finger protein, associated with a common viral integration site in murine leukemias. It is suggested that Evi-1 plays important roles in embryogenesis and transformation of myeloid cells. To elucidate mechanisms by which Evi-1 induces such biological effects, we analyzed the relationship between Evi-1 and AP-1 which could regulate cellular proliferation and differentiation. When Evi-1 was expressed, transactivation through a 12-O-tetradecanoylphorbol 13-acetate-responsive element was observed in NIH3T3 and P19 cells. Evi-1-transfected P19 cells showed some differentiated phenotypes and increased expression of endogenous c-Jun and c-Fos. These results indicate that Evi-1 raises AP-1 activity. Evi-1 caused stimulation of the c-fos promoter transactivation, which seems to be a main mechanism of AP-1 activation, through at least two portions of the promoter. Evi-1 has the first zinc finger domain at the N terminus and the second zinc finger domain near the C-terminus. We constructed deletion mutants of Evi-1 and investigated the functions of these domains. It was shown that the second zinc finger domain is essential for the activation of AP-1 and transactivation of the c-fos promoter.     

Chronologic changes in the clinicopathologic findings and survival of gastric cancer patients

PURPOSE: To determine the chronologic changes in the clinicopathologic features of gastric cancer patients. PATIENTS AND METHODS: The clinicopathologic findings of 1,795 patients with gastric cancer were examined retrospectively from hospital records obtained between 1969 and 1995. The patients were divided into three generations on the basis of chronologic order. The first generation included patients treated over the period 1969 to 1977; the second generation, 1978 to 1986; and the third generation, 1987 to 1995. RESULTS: The chronologic changes in the clinicopathologic findings for all gastric cancers included increases in the superficial type based on macroscopic appearance (P < .005), small-sized tumor (P < .025), superficial depth of invasion (P < .005), and earlier histologic stages (P < .005), in addition to a decrease in lymph node metastasis (P < .005). Overall, the postoperative survival rate has improved over time in gastric cancer patients, with 5-year survival rates of 36.0%, 53.3%, and 68.6% in the first, second, and third generations, respectively. In stages 1,2, and 3, the survival rate in the third generation was the highest of the three generations, whereas in stage 4, the survival rate did not differ between the three generations. Patients who underwent a D2 dissection showed a higher survival rate than those with D1 or D3 dissections, but there was no statistical difference in the survival of patients with D1, D2, and D3 dissections when stage 4 patients were excluded. CONCLUSION: The chronologic changes in gastric cancer patients over the past 27 years have included an increase in the incidence of earlier-staged gastric cancers, which has had a significant impact on the improved postoperative survival rate.     

A high-packing density pixel with punchthrough read-out method foran HDTV interline CCD

A new pixel structure for a high-packing-density interline CCD is proposed, in which signal charges are read out from the photodiodes to the vertical CCD by a punchthrough mechanism. This read-out method makes it possible to reduce the depth of the VCCD channel and the second p-well by implanting these two layers after diffusion of the photodiode n layer. Spreading resistance measurements on dummy wafers show that the depths of these layers are 0.28 μm and 0.6 μm, respectively. Moreover, the photodiode n-layer is covered with a surface p⁺-layer, even at the transfer region. We describe the results of simulations and experiments on a test image sensor with pixel dimensions of 7.3 μm (H)×7.6 μm (V). From the experimental data, we estimate the characteristics of an image sensor with pixel dimension 5.0 μm (H)×5.2 μm (V). Such a device should have a maximum charge handling capability of 1.4×10⁵ electrons, a smear level of -88 dB, a sensitivity of 1.5×10³ electrons/Ix with a 30% fill factor, no image lag, and a low photodiode dark signal of less than 14 electrons at 60°C. These results indicate that an IL-CCD with a punchthrough readout structure is suitable for image sensors with a high pixel density such as 2/3 inch 2 million pixel image sensors for high-definition TV applications     

Combination treatment with cisplatin and schizophyllan for 7,12-dimethylbenz(a)anthracene-induced rat ovarian adenocarcinoma

OBJECTIVE: Experimental chemotherapy was conducted to investigate the combined effect of Schizophyllan (SPG) and Cisplatin (CDDP). METHODS: Rats with 7,12-dimethylbenz(a)anthracene (DMBA)-induced ovarian adenocarcinoma received SPG and/or CDDP, were observed for the anti-tumor effect of the drugs and were subjected to immunohistochemical study. RESULTS: 1) Tumor reduction was enhanced by the combined use of SPG and CDDP; 2) The survival rate of rats given SPG alone was significantly higher than that of the control rats, and treatment with SPG combined with CDDP tended to improve the survival rate; 3) Immunohistochemically, an infiltrative increase in cytotoxic T-lymphocytes (CTL) was induced, although the development of helper T-cells and macrophages was immunohistochemically weak at the tumor site. CONCLUSION: The administration of SPG enhanced the anti-tumor effect of CDDP.