In vitro differentiation of a cloned bovine mammary epithelial cell

The aim of the study was to establish in vitro a bovine mammary epithelial cell (MEC) clone, able to respond to mitogenic growth factors and to lactogenic hormones. Mammary tissue from a 200-d pregnant Holstein cow was used as a source of MEC, from which a clone was established through a process of limiting dilution. When plated on plastic, the cells assumed a monolayer, cobblestone, epithelial-like morphology, with close contact between cells. Inclusion of IGF-1 and EGF in the media significantly increased the number of cells 5 d after plating. All cells stained strongly for cytokeratin and moderately for vimentin at young and old passage stages, indicating the epithelial nature of this cell clone. When the cells were plated at a high density on a thin layer of a commercial extracellular matrix preparation (Matrigel), lobular, alveoli-like structures developed within approximately 5 d, with a clearly visible lumen. When cells were plated onto Matrigel in differentiation media (containing lactogenic hormones), detectable quantities of alpha-casein were present in the media and particularly on the lumen side of the structures. Omission of one of the lactogenic hormones (insulin, prolactin or hydrocortisone) reduced alpha-casein release to the limit of detection of the assay used. Lactoferrin was also produced when the cells were plated on Matrigel, again principally on the lumen side of the lobules, though this was independent of the lactogenic hormones. By passage 40, the cells had senesced, and it was not possible to induce alpha-casein or lactoferrin production. This study notes the establishment of a functional bovine mammary epithelial cell clone, which is responsive to mitogenic and lactogenic hormones and an extracellular matrix.     

Contrasting Lubrication Properties of Imidazolium-Based Ionic Liquids Affected by the Nature of the Surface Under High Vacuum

The lubrication performance of imidazolium-based ionic liquids was evaluated under high vacuum using a ball-on-disk tribometer. A ball and a flat disk made of SUS440C stainless steel were used as specimens. A surface of the as-received flat disk specimen was covered with a thick oxide layer (>40 nm). For an examination of the effect of the surface oxide layer on the tribological performance of the ionic liquids under high vacuum, another specimen with a thin oxide layer (approx. 4 nm thick) was prepared. The ionic liquids with the TFSA anion showed better lubrication performance with the thicker oxide layer specimen, whereas the ionic liquids with the BF4 anion showed superior performance with the thinner oxide layer specimen. These results are discussed based on the HSAB principle. It is shown that the mechanism of the opposite tribological characteristics can be reasonably explained in terms of the chemical hardness by the HSAB principle.     

Phase-matched high-order harmonic generation by guided intensefemtosecond pulses

We describe the phase-matched high-order harmonic generation of femtosecond Ti:sapphire laser pulses a with two different guiding methods. Generation efficiency of the high-order harmonic was improved by phase-matched propagation in the guiding channel. More than 100-fold enhancement around the 25th harmonic (32 nm) was obtained with a 3-cm-long Ar-filled hollow fiber. The harmonics around the 49th harmonic (16 nm) were also enhanced by two orders of magnitude compared to those in the plateau with a 7-mm-long, self-guided pulse in Ne. High-harmonic conversion efficiency of 10^-6 was obtained by phase-matched propagation in Ne, producing >nJ harmonics in the cutoff region around the 49th harmonic. In both experiments, the harmonics near the cutoff region were preferentially enhanced. The results are well explained by considering both the intrinsic phase based on the single-atom response and the macroscopic phase matching in the high-intensity interaction region. The flat intensity profile achieved in the guided structure is considered to clearly manifest the intrinsic phase behavior of the harmonics     

Interleukin-6 (IL-6) inhibits thyroid function in the presence of soluble IL-6 receptor in cultured human thyroid follicles

Interleukin-6 (IL-6), a pleiotropic cytokine, is postulated to be involved in the pathogenesis of sick euthyroid syndrome, although the direct in vitro effects of IL-6 on human thyroid function are controversial. Because IL-6 signal can be transduced when the complex of IL-6 and soluble IL-6 receptor (sIL-6R) binds to gp 130, an IL-6 signal transducer, we studied the effects of IL-6 and sIL-6R on thyroid function, using human thyroid follicles obtained from patients with Graves' disease. IL-6 alone had no inhibitory effect on TSH-induced thyroid function (125I incorporation and organic 125I release), even at supraphysiological concentrations. However, in the presence of physiological concentrations of sIL-6R (100 ng/ml), IL-6 inhibited thyroid function dose dependently and completely, accompanied with the decreased ratio of 125I-T3/125I-T4 not only in the thyroid follicles but also in the culture medium. Thyroid follicles did not secrete sIL-6R but produced IL-6 constitutively. Consistent with these findings, sIL-6R inhibited thyroid function slightly at high concentrations. Furthermore, RT-PCR analyses revealed that human thyroid follicles expressed the messenger RNAs for IL-6 and gp130 but scarcely messenger RNA for IL-6R. These in vitro findings suggest that IL-6 alone hardly affects thyroid function in thyroid follicles in which IL-6R gene is scarcely expressed. However, because sIL-6R is present abundantly in serum, IL-6 in vivo would be capable of inhibiting the synthesis and release of T4 and, to a greater extent, T3 from the thyroid gland. These in vitro findings are at least partly related to the development of sick euthyroid syndrome.     

Crosstalk reduction in N×N WDM multi/demultiplexers bycascading small arrayed waveguide gratings (AWG's)

This paper shows a new scheme which improves the crosstalk performance of large optical multi/demultiplexers, a key component in wavelength division multiplexing (WDM) systems. This scheme uses arrayed waveguide gratings (AWG's) of various sizes and requires no additional equipment. It is well known that a large multi/demultiplexer can be constructed by cascading small multi/demultiplexers. We have studied the impact of the number and size of AWG stages on crosstalk performance. This paper proves that to obtain a multistage multi/demultiplexer with minimum crosstalk, the total channel number of each AWG stage must be minimized. For example, cascading 10-channel AWG's and 11-channel AWG's improves the crosstalk performance of a 110-channel multi/demultiplexer by about 7.5 dB. Furthermore, the crosstalk performance degradation due to fabrication error is theoretically investigated taking channel bandwidth into account. Optimum design parameters of multistage AWG's are introduced: When the AWG suppression ratio is 30 dB and the ratio of channel bandwidth to channel spacing is about 0.24, the degradation in crosstalk performance due to fabrication error is minimized. The tradeoff between the crosstalk performance and the efficiency in terms of hardware and wavelength are also discussed. It is discovered that this simple scheme can yield a crosstalk-free WDM router. Crosstalk reduction obtained by this scheme allows the realization of flexible multiwavelength networks based on wavelength routing     

A 40-GHz D-type flip-flop using AlGaAs/GaAs HBT's

We report master-slave D-type flip-flop (D-FF) circuit implemented with AlGaAs/GaAs HBT's. The fabricated HBT's had an f_T of 107 GHz and an f_max of 110 GHz. To maximize the speed, the logic swing and transistor size in the IC were optimized. In the D-FF, to facilitate the high-speed testing, a selector circuit was integrated on the same chip. As a result, the operation of this IC was confirmed up to 40 GHz, which is the highest speed in D-FF     

DC to 40-GHz broad-band amplifiers using AlGaAs/GaAs HBT's

In this paper, we report two types of broad-band amplifiers implemented with AlGaAs/GaAs HBT's. One is a Darlington feedback amplifier and the other is a transimpedance amplifier. In the former circuit, a dc gain of 9.5 dB and a -3-dB bandwidth of 40 GHz were achieved. In the latter circuit, a transimpedance gain of 50 dBΩ and a -3-dB bandwidth of 27 GHz were achieved. To our best knowledge, they are the highest speed in each circuit configuration     

Servo System Using Optical Serial Transmission in Control Loop for Industrial Robots

A new servo system suitable for robot control is proposed. An optical serial transmission is applied in its servo-control loops to reduce the number of signal cables and the cable length between the robot mechanism and the controlling equipment, as well as to increase flexibility for expanding control functions.