showing 36 of ~574560 from 574555 documents
Alternative splicing products of the tenascin gene distinguish rat liver fat storing cells from arterial smooth muscle cells and skin fibroblasts
1992
Abstract Fat storing-(Ito-)cells (FSC) transform into a myofibroblast-like cell type during liver fibrogenesis. A similar development can be observed in cell culture. At the moment, a definite marker to differentiate transformed FSC from smooth muscle cells (SMC) is not available. We recently found that FSC, SMC and skin fibroblasts (SF) synthesize tenascin, a novel matrix protein. As it is reported that various tissues express different tenascin forms by the mechanism of alternative pre-mRNA splicing, we analyzed the tenascin transcripts in these cell types. Total RNA extracted from cultured FSC, SMC and SF, analyzed by Northern blot hybridization, showed a 7.2 kb transcript in FSC, a 8.7 …
Electronic States in Mesoscopic Systems
1992
Abstract Electronic states in disordered systems are studied within the Anderson model of localization. By means of the Green's function technique we derive the transmission coefficient for electronic states through mesoscopic samples. The transmission coefficient is shown to be not self-averaging due to strong spatial fluctuations of the amplitude of the eigenstates, which are obtained by direct diagonalization of the respective secular matrices. The wave functions display a multifractal behaviour, characterized by the set of generalized fractal dimensions and the singularity spectrum of the fractal measure.
Characterization of bep1 and bep4 antigens involved in cell interactions during Paracentrotus lividus development
1992
Abstract We have identified and partially characterised two antigens, extracted with 3% butanol, from Paracentrotus lividus embryos dissociated at the blastula stage, and encoded by the cDNA clones previously described as bep1 and bep4 (bep-butanol extracted proteins). The cDNA fragments containing the specific central portions of bep1 and bep4 were expressed as MS2 polymerase fusion proteins in Escherichia coli. These two fusion proteins, called 1C1 (bep1) and 4A1 (bep4), were injected subcutaneously into rabbits and the corresponding polyclonal antibodies generated. Western blot analysis of proteins, extracted with 3% butanol, from sea urchin embryos at the blastula stage (b.e.p.), establ…
Eine Nierenfunktionsanalyse durch die Computertomographie
1992
The CT clearance in a number of urological patients (39 patients, 25 with normal renal function) was studied by means of an "area under curve" (AUC) method, using a region of interest. 31 patients were given meglumine ioxithalamate and 8 patients Iopamidol as a contrast medium. Both for total and partial function there was highly significant correlation with isotope clearance with good reproducibility. The difference in the pharmacokinetics of the contrast media affected the absolute clearance values.
Surface effects on kinetics of ordering
1992
We study the effects of surfaces on the kinetics of phase changes in Ising-type systems. If the surface effects can be modelled by a field which couples linearly to the local order parameter, the growth of wetting or drying layers occurs. The numerical solution of the corresponding time-dependent Ginzburg-Landau equation yields a temporally logarithmic growth for the thickness of a wetting (drying) layer growing from an unstable dry (wet) state. On the other hand, if one starts off with a metastable state, the radius of a supercritical plug (wet or dry) grows linearly in time, in accordance with recent experimental results.
199 Causal Classes of Space-Time Frames
1992
It is shown that from the causal point of view Minkowskian space-time admits 199, and only 199, different classes of frames.
Simulation of cluster impact fusion
1992
We report molecular dynamics simulations of the impact of TiD clusters on TiD targets. In each cluster collision the total fusion probability seems to be due to a single deuterium deuterium collision. The kinetic energies of incident deuterium atoms gradually level off around the initial cluster energy, but do not reach the high energy tail of a corresponding Maxwell-Boltzmann distribution. Neither any other support for a thermonuclear fusion mechanism was observed. On the contrary, our simulations imply that the enhanced fusion rate is rather due to channeled many atom collision cascade type mechanism.
Signature inversion in 120Cs: Evidence for a residual pn interaction
1992
Abstract High-spin states have been observed in the odd-odd isotope 120Cs in 32S-induced reactions. The previously known band is extended to higher spin and several new bands are identified. Band-head configurations have been inferred by comparing the band properties with known bands in the odd nuclei 121Cs and 121Ba. A remarkable signature inversion is observed in the π h 11 2 ⊗ν h 11 2
Flow cytometric immunophenotyping: principles and pitfalls
1992
Within the last decade flow cytometry (FCM) has become an integral part of basic immunological research. Elaboration of this technology has been intensively stimulated by a rapidly growing sophistication in monoclonal antibody technology and vice versa. At present numerous applications are established that allow an increasingly detailed insight into the immune system, however, automation still must be considered the "cinderella of the arts". Thus, transition of this powerful approach from a basic to a routine clinical procedure is much more difficult than expected. Sufficient usage of flow cytometers still requires some knowledge of physics and its technical applications. Moreover, several …
An efficient excitation scheme for resonance ionization of tin in a laser ion source
1992
An efficient three-colour, three-step resonant excitation/ionization scheme has been found for tin that leads from the 5p23P2 level of the ground-state multiplet via two excited atomic levels (λ1 = 317.51 nm and λ2 = 811.40 nm) to an autoionizing state 9s3P2(λ3 = 823.49 nm) at 59375.9 cm−1. This excitation path permits the saturation of all transitions with the limited power available from a copper vapour laser pumped dye laser system (Esat ≈ 1.5 mJcm2 for λ3). The high repetition rate of such a laser system is essential for a highly efficient laser ion source.
The generation of the ϱ-resonance by QCD
1992
By showing that the imaginary part of a suitable QCD amplitude, after extrapolation up to the cut, exhibits indeed a prominent bump structure where the ϱ-resonance is expected to be, a rather direct indication for the generation of the ϱ-resonance by QCD is given. This is achieved by using a mathematically rigorous method of stable analytic extrapolation, based on the theory of maximally converging sequences of polynomials and the application of conformal mappings.
Induction of micronuclei in V79 Chinese hamster cells by tetrachlorohydroquinone, a metabolite of pentachlorophenol
1992
Tetrachlorohydroquinone, a metabolite of the fungicide pentachlorophenol, induced significant dose-related increases in micronuclei in V79 Chinese hamster cells without exogenous metabolic activation. The lowest observed effective dose was 10 microM, where the relative survival was about 62%. At the highest dose tested, 20 microM, the relative survival was about 8% and the frequency of cells with micronuclei was about 6 times the solvent control frequency. The induction of micronuclei by tetrachlorohydroquinone was significantly inhibited by the hydroxyl radical scavenger dimethyl sulfoxide at 5% (v/v).
Shape coexistence in 117I
1992
The 117I nucleus has been investigated in a high-spin gamma-spectroscopic study using the NORDBALL detector array. The observed level structures are interpreted as resulting from coexisting collect ...
Effects of eutrophication and organic loading on the occurrence of profundal harpacticoids in a lake in southern Finland.
1992
Harpacticoids made up 19 and 30% of the meiobenthos proper by number and 39 and 55% by biomass at maximum depths and a depth of 20 m, respectively, in Lake Paijanne. Harpacticoids accounted for higher proportions of the total meiobenthos in oligotrophic and unpolluted areas than in polluted areas. Seven species were identified, with Canthocamptus staphylinus confined to semi-lotic areas influenced by organic pollution from a pulp mill. Other species exhibited somewhat different distributions in oligotrophic and mesotrophic areas. Harpacticoid densities were most closely correlated with oxygen content and phytoplankton biomass, and correlations with environmental values were closer at maximu…
High-speed rotational angioplasty-induced echo contrast in vivo and in vitro optical analysis
1992
High-speed rotational angioplasty is being evaluated as an alternative interventional device for the endovascular treatment of chronic coronary occlusions. It has been postulated that this type of angioplasty device may produce particulate debris or cavitations that induce myocardial ischemia. To determine the clinical presence of myocardial ischemia during rotational angioplasty, echocardiographic monitoring for wall motion abnormalities was performed in 9 patients undergoing rotational atheroablation using the Auth Rotablator for 10-sec intervals at 150,000 and 170,000 rpm. No wall motion abnormalities were detected in 5 patients evaluated with transesophageal echocardiography or in 4 pat…
The Changing Pattern of Human Immunodeficiency Virus Type 1 Infection in Intravenous Drug Users
1992
A cross-sectional seroepidemiologic study was carried out between 1985 and 1990 in 1,567 heterosexual intravenous drug users who had been seen at the AIDS Regional Reference Center in Palermo, Italy, to evaluate the rate of human immunodeficiency virus type 1 (HIV-1) seroprevalence in this group and its long-term trend. Sixty serum samples collected from drug users in 1980 and 1983, before the founding of the Center (1985), were tested as well. Some demographic and behavioral risk factors were studied in a subgroup of intravenous drug users enrolled in 1985, 1987, and 1990 for their possible association with HIV-1. These factors were also studied in relation to hepatitis B virus infection, …
Myasthenia gravis associated with Charcot-Marie-Tooth neuropathy: report of a case
1992
We report the case of a 24 year old woman who developed myasthenia gravis in the course of a mild form of Charcot-Marie-Tooth neuropathy. We describe the clinical manifestations together with the neurophysiological, pathological, serological findings and response to therapy and discuss the unusual association in the light of the relevant literature. © 1992 Masson Italia Periodici S.r.l.
Translational and rotational diffusion in supercooled orthoterphenyl close to the glass transition
1992
Self diffusion coefficients in supercooled orthoterphenyl (OTP) have been determined down toD t =3·10−14 m2s−1 using a1H-NMR technique applying static field gradients up to 53T m−1 In a range of more than two decades theD t values agree with those of photochromic tracer molecules of the same size determined by forced Rayleigh scattering down to the glass transition temperatureT g . A change of mechanism is found for translational diffusion atT c ≈1.2T g whereD t is proportional to the inverse shear viscosityη −1 atT>T c butD t ∼η ξ with ξ=0.75 atT<T c . Rotational correlation times determined by2H-NMR stimulated echo techniques in deuterated OTP remain proportinal toη −1 down toT g . Our re…
Estudio comparativo de dos drenajes de pequeño calibre en el neumotórax espontáneo idiopático
1992
Se estudiaron comparativamente entre febrero de 1987 y diciembre de 1989, 79 neumotorax espontaneos idiopaticos, 40 de ellos drenados con tubos de calibre 12 F y los restantes con 10 F. El drenaje con tubos de pequeno calibre fue efectivo con una media de utilizacion de 5,2 ± 3,9 dias, requiriendo en solo un caso tratamiento quirurgico por fuga aerea persistente. No se encontraron diferencias significativas entre ambos grupos en cuanto a tiempo de drenaje, complicaciones y recidivas tras un seguimiento minimo de doce meses. Por ello, recomendamos el uso de drenajes de pequeno calibre en los neumotorax espontaneos idiopaticos, especialmente los de calibre 10 F, menos traumaticos y de similar…
Synaptic ribbons, spheres and intermediate structures in the developing rat retina
1992
The present study was conducted to investigate the qualitative and quantitative development of synaptic bodies in retinae of Wistar rats during postnatal days 4-28. In addition, the effects of different light regimens and of eye pigmentation on SB numbers were studied. Synaptic bodies were counted and measured in the outer plexiform layer of retinal tissue fixed and processed by routine electron microscopical techniques. At postnatal days 4 and 5, retinae showed only few synaptic bodies. The main numerical development of synaptic bodies occurred between postnatal days 4 and 9, numbers remaining more or less constant thereafter. The intracellular location of synaptic ribbons changed from pre…
Properties of dense nuclear and neutron matter with relativistic nucleon-nucleon interactions.
1992
Within the framework of the Dirac-Brueckner (DB) approach, the properties of dense nuclear and neutron matter are investigated using realistic nucleon-nucleon (NN) interactions which are derived from relativistic meson-field theory and describe the two-nucleon system quantitatively. Single-particle potentials, equations of state, nucleon effective masses, Landau parameters, and speeds of sound are calculated and analyzed as functions of density, for both nuclear and neutron matter. In the DB approach, the equation of state comes out stiffer than in the most sophisticated nonrelativistic calculation, but softer than in the Walecka model. Possible extensions of the present approach to nucleon…
On the long-term response of elastic-perfectly plastic solids to dynamic cyclic loads
1992
It is shown that the long-term response of an elastic-perfectly plastic solid subjected to dynamic actions cyclically varying in time is characterized by stresses, plastic strain rates and velocities that are all periodic with the same period of the external actions, and are in perfect analogy with the quasi-static case; on the other hand, plastic strains and displacements are in general nonperiodic (except in case of alternating plasticity) and may increase indefinitely (except when elastic or plastic shakedown occurs). Besides, the work performed by the external actions in the steady cycle equals the work performed by the elastic stresses (i.e. pertaining to the elastic response of the bo…
Dielectric polarization in PLZT X/65/35 and PbMg1/3Nb2/3O3at the diffuse phase transition
1992
Abstract The transformation of the hysteresis loops in PLZT x/65/35 in the region of diffuse phase transition is discussed in relation to the behaviour of dielectric permittivity. The Vogel-Fulcher type dielectric relaxation is used to describe the discussed phenomena.
Dielectric memory effects of (Mn, Fe, Co, Cu, Eu) doped PLZT ceramics
1992
Abstract Dielectric memory effects—effect of thermal memory (ETM) and effect of electric field memory (EFM) have been studied in (Mn, Fe, Co, Cu, Eu) doped PLZT ceramics. The obtained results have been discussed on the assumption that the ETM and EFM depends on relaxation of domain and interphase (polar and nonpolar) boundaries influenced by changes of defects conditions at doping.
The control of anti-coagulation in acute dialyses with sensitive laboratory parameters.
1992
In seven patients who had to be dialysed between four and 13 times due to acute renal failure, low molecular weight heparin (LMWH) Fragmin was used for anticoagulation. According to dose-finding studies, 80-90 U kg-1 body weight of LMWH as a single bolus were administered initially, producing dose-related levels of 0.3-1.5 anti-factor Xa U ml-1 in plasma. Apart from the anti-Xa activity in the plasma, the thrombin anti-thrombin III complex (TAT complex) and a fibrin degradation product (D-dimer) were measured as parameters of a coagulation activation. A sufficient anti-coagulation during dialysis was supposed to exist at a normal range (5.0 micrograms l-1 or below) of TAT complex. Pathologi…
Multiple actions of glaucine on cyclic nucleotide phosphodiesterases, α1-adrenoceptor and benzothiazepine binding site at the calcium channel
1992
1. In the present study, the properties of glaucine (an aporphine structurally related to papaverine) were compared with those of papaverine, diltiazem, nifedipine and prazosin. The work includes functional studies on rat isolated aorta contracted with noradrenaline, caffeine or KCl, and a determination of the affinity of glaucine at calcium channel binding sites of alpha-adrenoceptors, by use of [3H]-(+)-cis-diltiazem, [3H]-nitrendipine and [3H]-prazosin binding to cerebral cortical membranes. The effects of glaucine on the different molecular forms of cyclic nucleotide phosphodiesterases (PDE) isolated from bovine aorta were also determined. 2. Contraction evoked by noradrenaline (1 micro…
Magnetic excitations in an exchange-coupled tetramer cluster of cobalt (II): a study by inelastic neutron scattering
1992
Abstract The polyoxometalate K 10 [Co 4 (H 2 O) 2 (PW 9 O 34 ) 2 ].20H 2 O contains a ferromagnetically exchange-coupled tetramer of Co 11 encapsulated in between two diamagnetic molecules (PW 9 O 34 -9 . At 2.5K several inelastic peaks are observed in the energy range 1.5–7 meV, which are assigned to magnetic excitations in the cluster. A tentative interpretation of these data from an anisotropic exchange model yields a cobalt-cobalt interaction of 3meV (24cm -1 ) and an amount of anisotropy J xy / J z ≌0.6. These values are consistent with the magnetic susceptibility measurements.
Quasielastic neutrino (antineutrino) reactions in nuclei and the axial-vector form factor of the nucleon
1992
Abstract Quasielastic neutrino and antineutrino reactions in nuclei are studied to investigate the effect of the nuclear medium on the determination of axial dipole mass M A in nuclei. The calculations are done in the local density approximation and various nuclear effects like Pauli blocking, Fermi motion of nucleons and strong renormalization effects in the spin-isospin channel are taken into account. The nuclear effects are found to be quite large at low q 2 , but the data in this region are too meagre to influence the determination of M A . The experimental data on differential and total cross sections are found to be consistent with M A as determined from deuterium experiments and no c…
Lipid accumulation inTrichodermaspecies
1992
Two filamentous fungi, Trichoderma harzianum and Trichoderma viride, were compared for their ability to synthesize lipids on different carbon and nitrogen sources. Three culture media were selected for each strain after preliminary screening. All the test media were nitrogen-deficient (C/N = 60) so as to stimulate lipid accumulation. For both microorganisms the glucose-ammonium sulphate medium was the most conducive to lipid production: a lipid accumulation of 17% (w/w) of biomass dry weight was obtained for T. harzianum and of 32% (w/w) of biomass dry weight for T. viride. In sucrose-sodium nitrate medium T. harzianum was able to accumulate almost 25% (w/w) of its biomass in lipid form. Ho…
Cell surface display of rat invariant γ chain: detection by monoclonal antibodies directed against a C-terminal γ chain segment
1992
A series of 14 monoclonal antibodies (mAb) directed against the C-terminal part of the rat invariant gamma chain (amino acid 142-216) was generated using distinct fusion proteins that contain this gamma segment for immunization and hybridoma screening. Additional fusion protein were prepared carrying discrete regions of the gamma chain. Employing these reagents confirmed that the obtained mAb do indeed recognize the C-terminal portion of the invariant chain, as demonstrated by Western blot analysis. All mAb established recognize epitopes present on the native gamma chain, as revealed by immunoprecipitation analysis using nonionic detergent extracts of metabolically labeled Lewis rat splenoc…
Temperature and magnetic field dependent correlations in the singlet ground state system CsFeBr3
1992
The magnetic excitations in CsFeBr3 have been measured with inelastic scattering of cold neutrons to high precision at 80 mK. The fact that the lowest frequency mode softens with decreasing temperature but stabilizes at 0.11 THz below 2.5 K is the indication that CsFeBr3 remains a SGS system forT→0. From dispersion curves measured earlier in a magnetic field along the chain axis experimental intensities were derived and in turn correlation lengths. Correlation lengths were also calculated using the new parameters for exchange and anisotropy. The experimental results and the calculations both show that the correlation lengths increase for increasing magnetic field, flatten off around the pha…
Convergence and applications of vector rational approximations
1992
The Padé approximants and their generalizations are for many years the matter of intense researchs .Yet , many theoritical problems stay in suspense : problems of exitence and unicity , problems of convergence and acceleration of convergence .The purpose of the present work vas to give answers to such questions .In the first section we take an in terest in vector Padé approximants of matrix series .Conditions of existence and unicity ,results of convergence are given ,as also the link with the theory of Lanczos method for the resolution of linear Systems . We utilize also the vector Padé approximants to provide a simultaneous approximation of a function and its derivative .In the second sec…
H7, a protein kinase C inhibitor, increases the glutathione content of neuroblastoma cells
1992
AbstractIt is shown that the intracellular glutathione (GSH) concentration of neuroblastoma-2a cells in culture increases with a maximum at 24 h after starting treatment with 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (H7), an inhibitor of protein kinase C (PKC). Other inhibitors of this and other protein kinases, e.g. sphingosine, staurosporine, and HA 1004, at the concentrations tested, had a less marked or negligible effect on intracellular GSH concentration. 12-O-Tetradecanoylphorbol-13-acetate (TPA) was also tested and showed no significant effect 24 h after addition.
Terveyskasvatus tutkimus- ja koulutusalana sekä arjen käytäntöinä
1992
Artikkelissa esitellään terveyskasvatuksen yliopistollista asiantuntijakoulutusta, terveyskasvatustutkimuksen osa-alueita ja tutkimuskohteita sekä käytännön terveyskasvatuksen tehtäviä ja päämääriä. Terveyskasvatuksen neljä suurta tehtävää ovat sivistävä tehtävä, virittävä tehtävä, mielenterveystehtävä ja muutosta avustava tehtävä. Terveyskasvatustutkimuksen osa-alueina nähtiin terveyskasvatuksen teoreettinen tutkimus, terveyskäyttäytymistutkimus, terveyskasvatuksen arviointitutkimus sekä terveyskasvatuksen yhteiskunnallinen tutkimus. Terveyskasvatuksen kokonaisvaltaiseksi määritelmänä esitettiin seuraava: ”Terveyskasvatuksen tavoitteena on kasvatuksellisin ja viestinnällisin keinoin tukea …
Kaluza-Klein origin for the superstring tension
1992
The natural configuration space of a string in a background antisymmetric tensor potential is not loop space, but a principal U(1) bundle over loop space. This allows a Kaluza-Klein--like interpretation of the string tension as momentum along the U(1) fiber, and a similar interpretation is possible for a {ital p}-dimensional object. The higher-dimensional'' action incorporating this momentum as a dynamical variable is given for a {ital p}-dimensional supersymmetric extended object, in a general supergravity background. Its relevance, for a flat background, to classical anomalies'' in the supersymmetry algebra is explained.
GENERALIZED GAUGE TRANSFORMATIONS AND HIDDEN SYMMETRY IN THE STANDARD MODEL
1992
A recently proposed, new construction of the Standard Model based on the graded Lie algebra SU (2|1) is analyzed in some depth. The essential ingredient is an algebraic superconnection which incorporates both the gauge fields and the Higgs fields and whose curvature automatically leads to a spontaneously broken realization of the theory. The mechanism of hiding the original algebraic structure is unorthodox and is due to the specific, "noncommutative" realization of SU (2|1). The model is characterized by a constant background supercurvature which is invariant under arbitrary, constant SU (2|1) gauge transformations. This background field whose effect is analogous to the action of a consta…