Transforming activity of a newly cloned androgen-induced growth factor

Our previous study demonstrated that androgen-dependent growth of mouse mammary carcinoma cells (SC-3) was mediated through an induction of heparin-binding growth factor, termed as androgen-induced growth factor (AIGF). Here, we report that NIH3T3 cells stably transfected with AIGF expression vector exhibit the abilities of tumor formation in nude mice, focus formation in monolayer culture and colony formation in soft agar. Thus, this newly cloned growth factor can be categorized as an oncogene. In addition, androgen-induced enhancement of DNA synthesis in SC-3 cells can be blocked by simultaneous incubation with AIGF antisense oligonucleotides. The possibility is also addressed that AIGF exerts its biological activity through an interaction with fibroblast growth factor (FGF) receptor. Transfection of expression vector encoding a variant form of FGF receptor-1 cloned from SC-3 cells into FGF receptor-negative L6 cells results in AIGF-dependent inhibition of differentiation. These results demonstrate that the ability of androgen to elicit transformed phenotype of SC-3 cells is mediated through AIGF induction and its interaction with FGF receptor-1.     

Effect of ferrous ion on mildiomycin production by Streptoverticillium rimofaciens

A specific regulatory effect of ferrous ion on a biosynthesis of mildiomycin by Streptoverticillium rimofaciens was investigated. The minimal concentration of ferrous ion necessary for the maximal production of mildiomycin was about 8 micrograms/ml. The physiological effects of ferrous ion on the mildiomycin production were examined in the media with and without the ferrous ion. Addition of ferrous ion to the culture medium increased both the mildiomycin production (10 times) and an assimilation of ammonium-nitrogen, activities of peptidase and protease.     

Hepatocyte growth factor in glycerol-induced acute renal failure

Hepatocyte growth factor (HGF) facilitates the regeneration of injured kidney in acute renal failure (ARF). Here we investigated the HGF production in glycerol-induced ARF rats. HGF mRNA expression levels were elevated in liver, spleen, and lung 6-24 h after glycerol injection. Tissue HGF protein levels determined by an enzyme-linked immunosorbent assay also increased in liver and spleen, whereas they decreased in the injured kidney 24 h after injection. Immunohistochemical studies showed that the number of HGF-producing cells did not increase in the liver. HGF receptor/c-Met mRNA levels were elevated only in the kidney. These results indicate that HGF supplied in an endocrine manner may play an important role in the regenerating process following ARF.     

Characteristic localization of gp130 (the signal-transducing receptor component used in common for IL-6/IL-11/CNTF/LIF/OSM) in the rat brain

The localization of gp130, the signal transducing receptor component used in common for interleukin (IL)-6, IL-11, ciliary neurotrophic factor (CNTF), LIF and OSM, in the rat brain was demonstrated by immunohistochemistry using an antibody specific to gp130. The gp130 immunoreactivity was observed in both glial and neuronal cells. Two distinct neuronal staining patterns were observed. The first showed neuropil staining, observed mainly in telencephalic structures including the hippocampus, cerebral cortex and caudate-putamen. The second pattern was observed on the cytoplasmic membrane of neuronal somata and was found primarily in the lower brainstem, in the large neurons of the reticular formation, and in spinal and cranial motor neurons. Electron-microscopic analysis revealed that both types of gp130 immunoreactivity were primarily associated with the cytoplasmic membrane and were not localized exactly at synaptic sites. Further, gp130 immunoreactivity was also observed in the oligodendrocytes and subependymal zone. These widespread but characteristic patterns of gp130 immunoreactivity overlap well with those of IL-6 receptor and CNTF alpha chains, suggesting a role of cytokines and growth factors such as IL-6 and CNTF via gp130 in certain specific regions of the brain.     

Logic gate for optical input using monostable-bistable transitionof serially connected resonant tunnelling transistors

The authors demonstrate a novel optical logic gate consisting of two resonant tunnelling transistors connected in series. The logic gate is characterised by an optically controlled bistability of the gate and a small optical input power of 10 μW realised by using the monostable-bistable transition of the gate     

60-GHz-band coplanar MMIC active filters

This paper presents the design and performance of 60-GHz-band coplanar monolithic microwave integrated circuit (MMIC) active filters. To compensate for the loss of the passive filter, a resonator composed of a quarter-wavelength line is terminated by a circuit with a constant negative resistance over a wide frequency band. Cross-coupling is introduced to make the attenuation poles on both sides of the passband. We develop two types of two-stage filter: one with medium bandwidth and the other with narrow bandwidth. The former shows an insertion loss of 3.0 dB with a 3-dB bandwidth of 2.6 GHz and a rejection of larger than 20 dB at a 3-GHz separation from a center frequency of 65.0 GHz. This filter also shows a noise figure of 10.5 dB. The latter filter shows an insertion loss of 2.8 dB with a 10-dB bandwidth of 2.1 GHz at a center frequency of 65.0 GHz. It also shows an output power of 5.0 dBm at a 1-dB compression point. The loss variation due to temperature variation is successfully compensated using a gate bias control circuit. The size of the MMIC filters is 2.5 mm/spl times/1.1 mm.     

Endothelin-induced activation of mitogen-activated protein kinases in glomerular mesangial cells from normotensive and stroke-prone spontaneously hypertensive rats

1. Kinase assay in myelin basic protein (MBP) containing polyacrylamide gels revealed that endothelin-1 (ET-1) and ET-3 increased MBP kinase activities in glomerular mesangial cells (MC) from Wistar-Kyoto (WKY) rats and spontaneously hypertensive rat (SHRSP). ET-1 stimulated MBP kinase activities more potently than ET-3. 2. Immunoprecipitation with anti-41-kDa MAPK antiserum showed that the MBP kinases activated by ET-1 correspond to 43- and 41-kDa MAPK. 3. Since Phorbol 12-myristate 13-acetate, a direct activator of protein kinase C, also activated MAPK, protein kinase C was suggested to mediate ET-induced activation of MAPK. 4. These results suggest that MAPK may mediate the ET actions in glomerular mesangial cells from normotensive rats as well as spontaneously hypertensive rats. Since ET is produced by vascular endothelial cells of the kidney and glomerular mesangial cells, the ET signalling pathway may have some physiological and pathophysiological significance in vivo glomerulus.