Cloning of a novel signal-transducing adaptor molecule containing an SH3 domain and ITAM

We molecularly cloned a cDNA coding for a novel phosphotyrosine molecule with a 70 kDa molecular mass, named STAM (signal transducing adaptor molecule), which is tyrosine-phosphorylated rapidly after stimulation with various cytokines such as IL-2, IL-3, IL-4, IL-7, GM-CSF, EGF and PDGF. STAM contains an SH3 (Src-homology 3) domain and the ITAM (immunoreceptor tyrosine-based activation motif), suggesting that STAM acts as an adaptor molecule involved in signal transducing pathways from the cytokine receptors.     

Carbon nanotubes prepared from three-layered copolymer microspheres of acrylonitrile and methylmethacrylate

Carbon nanotubes (CNTs) were synthesized from fine three-layered copolymer microspheres using the polymer blend technique. Diameter of PMMA core/Poly(AN-co-MMA) shell-1/PMMA shell-2 microspheres, prepared by a radical soap-free emulsion polymerization of methylmethacrylate (MMA) and acrylonitrile (AN), was between 400 nm and 500 nm. Microspheres were subjected to melt-spinning at 305 °C, stabilizing in oxygen at 220 °C for 4 h, and finally carbonizing at 1000 °C for 30 min. FE-SEM study of carbonized sample revealed the presence of CNTs arrays on carbon blocks. Similar arrays were observed in a comparative CNTs sample prepared from three-layered microspheres with the pure PAN shells-1 layers. HRTEM showed that the CNTs derived from copolymer microspheres had different structure when compared to the control sample, i.e. CNTs often adhered to each other and contained the internal compartments. The insufficient PMMA shell-2 coating of copolymer microspheres is believed to be a reason for CNTs adhesion. The possible mechanisms of the carbon block formation and the adhesion of CNTs are introduced.     

How to identify water from thickener aqueous solutions by touch

Water detection is one of the most crucial psychological processes for many animals. However, nobody knows the perception mechanism of water through our tactile sense. In the present study, we found that a characteristic frictional stimulus with large acceleration is one of the cues to differentiate water from water contaminated with thickener. When subjects applied small amounts of water to a glass plate, strong stick-slip phenomena with a friction force of 0.46 ± 0.30 N and a vertical force of 0.57 ± 0.36 N were observed at the skin surface, as shown in previous studies. Surprisingly, periodic shears with acceleration seven times greater than gravitational acceleration occurred during the application process. Finite-element analyses predicted that these strong stimuli could activate tactile receptors: Meissner''s corpuscle and Pacinians. When such stimuli were applied to the fingertips by an ultrasonic vibrator, a water-like tactile texture was perceived by some subjects, even though no liquid was present between the fingertip and the vibrator surface. These findings could potentially be applied in the following areas: materials science, information technology, medical treatment and entertainment.     

Interaction of second and third domains of Japanese quail ovomucoid with ten mammalian trypsins

Second and third domains were prepared from Japanese quail ovomucoid and association equilibrium constants, Kas, were measured at 25 degreesC and pH 8 for these domains with trypsins from ten mammalian species: cat, cow, dog, guinea pig, hog, horse, man, rabbit, rat, and sheep. The values ranged from 108 M-1 to 1010 M-1 for the second domain-trypsin associations and from 106 M-1 to 108 M-1 for the third domain-trypsin associations. Changes in Ka values for the interactions between the trypsins and each domain are attributed to slight changes in surface conformation caused by the residue changes in the inhibitor-binding region other than the S1 pocket of the trypsin species. The representative of such residue changes is assumed to be the one observed at residue 217 of trypsin molecule. Concerning each trypsin, the Ka value with the second domain was always higher than that with the third domain. However, the ratios between the two equilibrium constants varied from 3 to 60 depending upon trypsin species. This means that amino acid changes in enzyme-contact residues other than the P1 site of the Kazal-type inhibitor can make it possible to recognize even a slight difference in inhibitor-binding surface among the enzymes with the same S1 pocket and highly similar overall three-dimensional structure.     

Transient complete left bundle branch block during epidural anesthesia with mepivacaine

A 65-year-old woman with ovarian tumor was scheduled for abdominal total hysterectomy and bilateral adnexectomy under epidural anesthesia. Preoperative examinations revealed no abnormalities including ECG. Twenty minites after the epidural injection of mepivacaine, widened QRS complexes, which were diagnosed as complete left bundle branch block (CLBBB) later, appeared on ECG. At that time, heart rate (HR) was 150.min-1. CLBBB disappeared when HR decreased to 110.min-1 following the administration of pindolol and verapamil. The operation was postponed. Exercise-treated ECG showed neither CLBBB nor ischemic change even when HR increased to 160.min-1. Two weeks later the operation was attempted again. CLBBB appeared again twenty minites after the epidural injection of mepivacaine. The CLBBB disappeared 5 minites after the induction of general anesthesia when HR decreased to 100.min-1. The operation was performed uneventfully. The effective refractory period (ERP) is shortened with the increase in HR, but the shortning of ERP varies in different part of the cardiac conduction system. In tachycardia, ERP of left bundle branch is longer than that of right one. Because the cardiac conduction system is depressed by local anesthetics, it is speculated that ERP of left bundle branch is elongated further by mepivacaine and CLBBB appeared in this case.     

Carbonization of adamantane to a graphitizable carbon

Adamantane was carbonized in sealed tubes to 1073 K. Despite the non-planar molecular structure of adamantane, the resulting carbon was graphitizable. Using i.r. and u.v. spectrometry, mass spectrometry and X-ray diffraction, it was found that adamantane begins to decompose at ≈ 823 K to yield such planar molecules as phenanthrene, methyl-phenanthrene and pyrene. These molecules lead to a graphitizing carbon through a carbonization process which is similar to that of a pitch.     

Synthesis of soluble poly(9,10-dihydrophenanthrene-2,7-diyl)s. A new class of luminescent poly(p-phenylene)s with ethylene type bridges

Poly(9,10-dihydrophenanthrene-2,7-diyl)s with -OSi(R)₂(R′) groups at the 9,10-positions were synthesized by dehalogenative polycondensation of the corresponding monomers by using a zerovalent nickel complex. They showed number average molecular weights (M_n's) of 9800-69,000 and high quantum yields (62%-quantitative) in photoluminescence. Palladium catalyzed copolymerization of 2,7-dibromo-9,10-dihydrophenanthrene having -OCH₃ or -OSi(R)₂(R′) groups at the 9,10-positions with diethynyl- or diboronic-aromatic compounds also gave photoluminescent polymers with high quantum yields.