Showing papers by "Osaka University published in 1985"

Measurements of Interaction Cross-Sections and Nuclear Radii in the Light p Shell Region

Abstract: Interaction cross sections (${\ensuremath{\sigma}}_{I}$) for all known Li isotopes ($^{6}\mathrm{Li}$-$^{11}\mathrm{Li}$) and $^{7}\mathrm{Be}$, $^{9}\mathrm{Be}$, and $^{10}\mathrm{Be}$ on targets Be, C, and Al have been measured at 790 MeV/nucleon. Root mean square radii of these isotopes as well as He isotopes have been deduced from the ${\ensuremath{\sigma}}_{I}$ by a Glauber-type calculation. Appreciable differences of radii among isobars ($^{6}\mathrm{He}$-$^{6}\mathrm{Li}$, $^{8}\mathrm{He}$-$^{8}\mathrm{Li}$, and $^{9}\mathrm{Li}$-$^{9}\mathrm{Be}$) have been observed for the first time. The nucleus $^{11}\mathrm{Li}$ showed a remarkably large radius suggesting a large deformation or a long tail in the matter distribution.

Double beta Decay and Majorana Neutrino

Abstract: This review consists of three parts: Various properties of the quantized neutrino fields are summarized in part I from the viewpoint that a Dirac neutrino consists of two Majorana neutrinos with a degenerate mass but with opposite CP sings. It is shown why the Dirac neutrino has a freedom of the phase transformation to guarantee the lepton number conservation, while the Majorana neutrino does not.

Evaluation of the new system (umu-test) for the detection of environmental mutagens and carcinogens

Abstract: The umu operon in Escherichia coli is responsible for chemical and radiation mutagenesis, and the expression of the operon itself is inducible by these DNA-damaging agents. The principle of the umu -test is based on the ability of the DNA-damaging agents, most of which are potential carcinogens, to induce the umu operon. A plasmid (pSK1002) carrying a fused gene umuC′-′lacZ was introduced into Salmonella typhimurium TA1535. The strain TA1535/pSK1002 enabled us to monitor the levels of umu operon expression by measuring the β-galactosidase activity in the cells produced by the fusion gene. Using this strain, a simple, inexpensive, and sensitive system, the umu -test, for the screening of environmental mutagens and carcinogens was developed. 38 chemicals with different structures and modes of action, including 31 known animal carcinogens, were examined by the test to evaluate the system. The threshold sensitivity of the umu -test was approximately equal to that of the Ames test for chemicals genotoxic in both tests. By the umu -test, using the single tester strain, we detect many types of DNA-damaging agents for which the Ames test requires several tester strains. Furthermore, the umu -test provides a potential practical advantage for the screening of various environmental samples containing amino acids and nutrients such as urine, serum and foods.

Synthetic and natural Escherichia coli free lipid A express identical endotoxic activities

Abstract: The recently chemically synthesized Escherichia coli lipid A and the natural free lipid A of E. coli were compared with respect to their endotoxic activities in the following test systems: lethal toxicity, pyrogenicity, local Shwartzman reactivity, Limulus amoebocyte lysate gelation capacity, tumour necrotizing activity, B cell mitogenicity, induction of prostaglandin synthesis in macrophages, and antigenic specificity. It was found that synthetic and natural free lipid A exhibit identical activities and are indistinguishable in all tests.

Plasma Distribution Function in a Superthermal Radiation Field

Abstract: A plasma which is immersed in superthermal radiation suffers velocity-space diffusion which is enhanced by the photon-induced Coulomb-field fluctuations. This enhanced diffusion universally produces a power-law distribution ${(\frac{E}{{E}_{0}})}^{\ensuremath{-}\ensuremath{\kappa}}$ at energy $E$ larger than a critical energy ${E}_{0}$ where the transition energy ${E}_{0}$ and the power $\ensuremath{\kappa}$ are inversely proportional to the photon-field intensity.

Construction of chimaeric processed immunoglobulin genes containing mouse variable and human constant region sequences

Abstract: The specificity of monoclonal antibodies provides a powerful diagnostic and therapeutic tool in investigating human neoplasia. Radiological scanning and immunotherapy with mouse tumour-specific monoclonal antibodies have been applied to patients with some success, but a major problem is the neutralization of the mouse antibody induced by repeated administration of heterologous antibodies. To avoid or reduce such immune reactions, chimaeric immunoglobulins consisting of mouse variable (V) and human constant (C) regions can be synthesized. We have constructed a recombinant retrovirus DNA carrying genomic heavy-chain (H) variable-diversity joining (VH-D-JH) and C gamma 1 genes from different species and show here that the chimaeric intervening sequences are spliced out precisely. This procedure provides a useful method to construct the chimaeric mouse-human immunoglobulin gene to be expressed in Escherichia coli, yeast and animal cells. Unexpectedly, a hidden splice donor site in the 5'-flanking region of a human VH gene is used in place of the donor site of the leader sequence exon, resulting in the formation of the V region without the leader sequence.

A distributed mutual exclusion algorithm

Abstract: A distributed algorithm is presented that realizes mutual exclusion among N nodes in a computer network. The algorithm requires at most N message exchanges for one mutual exclusion invocation. Accordingly, the delay to invoke mutual exclusion is smaller than in an algorithm of Ricart and Agrawala, which requires 2*(N - 1) message exchanges per invocation. A drawback of the algorithm is that the sequence numbers contained in the messages are unbounded. It is shown that this problem can be overcome by slightly increasing the number of message exchanges.

GABAergic neurons containing CCK-8-like and/or VIP-like immunoreactivities in the rat hippocampus and dentate gyrus.

Abstract: The coexistence of cholecystokinin-octapeptide-like (CCK-L) and/or vasoactive-intestinal-polypeptide-like immunoreactive (VIP-LI) materials and glutamate decarboxylase (GAD) was studied in the rat hippocampus and dentate gyrus by means of immunohistochemistry. Consecutive 40-μm-thick sections were incubated in different antisera and those cells which were bisected by the plane of sectioning so as to be included at the paired surfaces of two adjacent sections were identified. The coexistence of the immunoreactivities for these peptides and GAD in the same cell could thus be determined by observing the immunoreactivity of the two halves of the cell, incubated in two different antisera. Almost all of the CCK-LI neurons were also GAD immunoreactive, whereas only about 10% of the GAD-immunoreactive neurons were CCK-LI. The percentages of GAD-immunoreactive neurons which were also immunoreactive for CCK were dependent on the laminar area in which they were found: i.e., 15–20% in the stratum radiatum of the hippocampus, about 10% in the stratum pyramidale, and about 6% in the stratum oriens. In contrast to the CCK-LI neurons, only about 40% of the VIP-LI neurons were identified to be also GAD immunoreactive, which might correspond to only part of the GAD-immunoreactive neurons. Furthermore the coexistence of VIP-LI and CCK-LI materials was recognized in about 10% of the CCK-LI neurons or about 35% of the VIP-LI neurons, indicating that some GABAergic neurons (presumably about 1%) in the rat hippocampus and dentate gyrus may contain both CCK-LI and VIP-LI materials.

Modeling and feedback control of a flexible arm

Abstract: When a flexible arm is rotated by a motor about an axis through the arm's fixed end, transverse vibration may occur. The motor torque should be controlled in such a way that the motor rotates by a specified angle, while simultaneously stabilizing vibration of the flexible arm so that it is arrested as soon as possible at the end of rotation. In this paper, we first derive a partial differential equation and a set of boundary conditions governing the vibration. Then, a feedback control system which incorporates a dynamic compensator is designed using sensor outputs. A set of experiments has been constructed to demonstrate control strategies for a flexible arm, where a strain gage was used as a vibration sensor and a microcomputer was equipped as a controller. Several satisfactory experimental results are shown.

Methionine or not methionine at the beginning of a protein

Abstract: Methionine aminopeptidases with a universal specificity have been revealed from the sequences of the amino-terminal region of mutant forms of yeast iso-1-cytochrome c and from a systematic examination of the literature for amino-terminal sequences formed at initiation sites. The aminopeptidase removes amino-terminal residues of methionine when they precede certain amino acids, with a specificity that appears to be determined mainly by the residue adjacent to the methionine residue at the amino terminus. The result with the mutationally altered iso-1-cytochromes c and the results from published sequences of other proteins from a wide range of prokaryotes and eukaryotes suggest that the aminopeptidase usually cleaves amino-terminal methionine when it precedes residues of alanine, cysteine, glycine, proline, serine, threonine and valine but not when it precedes residues of arginine, asparagine, aspartic acid, glutamine, glutamic acid, isoleucine, leucine, lysine or methionine. We suggest that the specificity is almost always determined simply by the size of the side chain of the penultimate residue; methionine is usually cleaved from residues with a side chain having a radius of gyration of 1·29 A or less, but is not cleaved from residues with larger side chains.

Mathematical Modeling of Porosity Formation in Solidification

Abstract: Shrinkage porosity and gas porosity occur simultaneously and at the same location when conditions are such that both may exist in a solidifying casting. Porosity formation in a solidifying alloy is described numerically, including the possible evolution of dissolved gases. The calculated amount and size of the porosity formed in Al-4.5 pct Cu plate castings compares favorably with measured values. The calculated distribution of porosity in sand cast Al-4.5 pct Cu plates of 1.5 cm thickness matches experimental measurements. The decrease of the hydrogen content by strong degassing and the increase of mold chilling power are recommended to produce sound aluminum alloy castings. The calculated results for steel plate castings are in agreement with the experimental work of Pellini. The present modeling has clarified the basis of empirical rules for soundness and suggests that the simultaneous occurrence of shrinkage and gas evolution is an essential mechanism in the formation of porosity defects.

Sliding distance of actin filament induced by a myosin crossbridge during one ATP hydrolysis cycle

Abstract: Muscle contraction results from a sliding movement of actin filaments induced by myosin crossbridges on hydrolysis of ATP1,2, and many non-muscle cells are thought to move using a similar mechanism3–5. The molecular mechanism of muscle contraction, however, is not completely understood6,7. One of the major problems is the mechanochemical coupling at high velocity under near-zero load8–13. Here, we report measurements of the sliding distance of an actin filament induced by a myosin crossbridge during one ATP hydrolysis cycle in an unloaded condition. We used single sarcomeres from which the Z-lines, structures which anchor the thin filaments in the sarcomere, had been completely removed by calcium-activated neutral protease (CANP)14 and trypsin, and measured both the sliding velocity of single actin filaments along myosin filaments and the ATPase activity during sliding. Our results show that the average sliding distance of the actin filament is ≥600 A during one ATP cycle, much longer than the length of power stroke of myosin crossbridges deduced from mechanical studies of muscle, which is of the order of 80 A (for example, ref. 15).

Synthetic lipid A with endotoxic and related biological activities comparable to those of a natural lipid A from an Escherichia coli re-mutant.

Abstract: A synthetic compound (506), beta (1-6) D-glucosamine disaccharide 1,4'-bisphosphate, which is acylated at 2'-amino and 3'-hydroxyl groups with (R)-3-dodecanoyloxytetradecanoyl and (R)-3-tetradecanoyloxytetradecanoyl groups, respectively, and has (R)-3-hydroxytetradecanoyl groups at 2-amino and 3-hydroxyl groups, exhibited full endotoxic activities identical to or sometimes stronger than those of a reference lipid A from an Escherichia coli Re-mutant (strain F515). Endotoxic activities tested include pyrogenicity and leukopenia-inducing activity in rabbits, body weight-decreasing toxicity in normal mice, lethal toxicity in galactosamine-sensitized mice and chicken embryos, and the preparation and provocation of the local Shwartzman reaction in rabbits. Compound 406, a synthetic counterpart of a biosynthetic precursor of lipid A molecule, showed by contrast only weak activities in all of the above assay systems except for the lethality in galactosamine-loaded mice. This finding strongly suggests that the presence of acyloxyacyl groups at the C-2' and C-3' positions of the disaccharide backbone is one of the most important determinant structures of the lipid A molecule for exhibition of strong biological activities characteristic of lipopolysaccharide and its lipid A moiety. The activities of the corresponding 4'-monophosphate (compound 504) and 1-monophosphate (505) analogs were considerably less than those of the parent molecule 506 and the reference F515 lipid A. Regarding other biological activities, not only compound 506 but also compounds 504, 505, and 406 showed definite activities, sometimes comparable to those of F515 lipid A and other reference natural products. These are the activation of Tachypleus tridentatus amoebocyte clotting enzyme cascade and human complement via the classical pathway, mitogenic and polyclonal B-cell activation of murine splenocytes, stimulation of peritoneal macrophages in a guinea pig, enhancement of migration of human blood polymorphonuclear leukocytes, and induction of a serum factor that is cytostatic and cytocidal to L-929 cells in Mycobacterium bovis BCG-primed mice. Relative potencies of test synthetic compounds depended on the assay systems and varied from one system to another. Dephospho-compound 503 lacked most of the biological activities that were definitely observed with phosphorylated compounds, probably because of its insolubility. This study demonstrates the successful chemical synthesis of an E. coli-type lipid A.

Reversible cyclic AMP-dependent change in distribution of myosin thick filaments in Dictyostelium.

Abstract: Myosin is thought to act as a major mechanochemical transducer in non-muscle cell motility1, but the in situ organization of the molecules has not yet been determined. Here we report the localization of myosin ‘rods’, analogous to the thick filaments of muscle, by ameliorated immunofluorescence and demonstrate the dynamic translocation of these rods in response to exogenously added cyclic AMP, which is a chemoattractant for Dictyostelium amoebae. On addition of cyclic AMP, we observed instantaneous shedding of the endoplasmic myosin followed by an increase in cortical rods, the original distribution being recovered in a few minutes. We conclude that myosin filaments mediate Dictyostelium cell movement, probably by an assembly/disassembly cycle of the molecules in response to a chemotactic stimulus.

Subtilosin A, a New Antibiotic Peptide Produced by Bacillus subtilis 168: Isolation, Structural Analysis, and Biogenesis

Abstract: Subtilosin A, a new antibiotic produced by Bacillus subtilis 168, was extracted from culture medium with n-butanol and purified to homogeneity by a combination of gel filtration and thin-layer chromatography. The yield was 5.5 mg from a liter of culture. It had bacteriocidal activity against some gram-positive bacteria. Amino acid analysis and mass spectrometry showed that it was a peptide with a molecular weight of 3398.9, consisting of 32 usual amino acid and some non-amino acid residues. Its amino- and carboxyl-termini were blocked. By analysis of the fragments obtained by partial acid hydrolysis, as well as by chymotryptic and thermolysin digestions of reduced and S-carboxymethylated samples and Achromobacter protease I digestion of performic acid-oxidized samples, the amino acid sequence was determined to be as follows: X-Gly-Leu-Gly-Leu-Trp-Gly-Asn-Lys-Gly-Cys-Ala-Thr-Cys-Ser-(sequence; see text) Ile-Gly-Ala-Ala-Cys-Leu-Val-Asp-Gly-Pro-Ile-Pro-Asp-Glx-Ile-Ala-Gly-Ala. The analyses of cross-linking structures revealed that there were linkages between the amino- and carboxyl-termini and between the Cys-19 and the Glx-28 residues through an unknown residue with a residue weight of 163. Consequently, subtilosin A was deduced to be a cyclic peptide antibiotic with a novel cross-linking structure. The production of subtilosin A begins at the end of vegetative growth and finishes before spore formation. Studies on the correlation between the production of subtilosin A and spore formation with decoyinine in the original strain and in asporogenous mutants of B. subtilis 168 suggested that there was no close correlation between the two phenomena. The production of subtilosin A was repressed by inhibitors of protein and RNA synthesis in contrast to that of many other antibiotic peptides, suggesting that it is synthesized by the mechanism of usual protein synthesis.

Unique structure of murine interleukin-2 as deduced from cloned cDNAs

Abstract: Interleukin-2 (IL-2) is a lymphokine originally described as a humoral factor required for the continued proliferation of activated T-cell clones. It also seems to be involved in the mitogenic response of thymocytes, in augmenting natural killer cell activity, in the generation of cytotoxic T cells and in the induction of other lymphokines such as gamma-interferon and a B-cell growth factor (BCGF-1). More recently, there has been evidence for the involvement of IL-2 per se in the stimulation of B-cell growth (ref. 10 and T. Kishimoto and J. Vilcek, personal communications). We have reported previously the cloning and expression of a human IL-2 complementary DNA. The cDNA encodes biologically active IL-2 which would consist of 153 amino acids, including a signal sequence. Because so much of the work on IL-2 has been done in the human and mouse, we sought to obtain cDNA encoding murine IL-2, and we now report the cloning, expression and sequence analysis of murine IL-2 cDNAs. The longest cDNA insert encodes a polypeptide of 169 amino acids, containing unique repeats of a CAG sequence which would encode 12 consecutive glutamine residues within the active IL-2 molecule.

Learning control theory for dynamical systems

Abstract: Three types of learning control laws are proposed for mechanical or mechatronics systems with linear and nonlinear dynamics, which may be operated repeatedly at low cost. Given a desired output Yd over a finite time duration [0,T] and an appropriate input u0, these laws are formed by the following simple iterative processes: 1) uk+1 = uk + ?(yd - yk), 2) uk+1 = uk + ?d/dt(yd - yk), and 3) uk+1 = uk + (? + ?d/dt)(yd - Yk), where uk(uk+1) denotes the kth(k+1th) input, Yk the measured output at the kth operation corresponding to uk, and ? and ? positive definite constant gain matrices. It is shown that the first law 1) with an appropriate gain matrix ? is convergent in the sense that Yk(t) approaches Yd(t) as k ? ? in the meaning of L2[0,T] norm if the objective system is linear and strictly positive. The same conclusion is also proved when the system is subject to a linear time-invariant or time-varying mechanical system. In addition, a rough sketch of the convergency proof of the second and third learning control laws is presented for a class of linear and nonlinear dynamical systems. Finally some discussions on potential applicabilities of these learning methods for robot controls are given.

Expression of the pX gene of HTLV-I: general splicing mechanism in the HTLV family.

Abstract: Human T-cell leukemia virus type I (HTLV-I) is an etiological agent of adult T-cell leukemia A viral gene pX encodes for p40X and it has been proposed that this protein trans-activates the viral long terminal repeat and possibly some cellular genes; this activation may be associated with T-cell transformation The mechanism of pX gene expression and the primary structure of p40X are now reported Two-step splicing generates the 21-kilobase pX mRNA; the initiator methionine for env becomes part of the pX protein These splicing signals are conserved among all members of the HTLV family except for the acquired immune deficiency syndrome-associated viruses