showing 36 of ~574560 from 574555 documents
Gap junctional intercellular communication of cultured rat liver parenchymal cells is stabilized by epithelial cells and their isolated plasma membra…
1994
The gap junctional intercellular communication (GJIC) determined by measuring dye coupling with Lucifer yellow, decreased within 3 d from 66% to 28% in monocultures of rat liver parenchymal cells. Coculturing of the parenchymal cells with a nonparenchymal epithelial cell line from rat liver resulted in increased and stabilized intercellular communication (83% after 3 d). The presence of isolated plasma membrane vesicles of the nonparenchymal epithelial cells also stabilized the intercellular communication between the liver parenchymal cells (70% after 3 d). When liver parenchymal cells were cocultured with a rat liver fibroblast cell line the gap junctional communication between the parench…
Bolus vs. continuous hepatic arterial infusion of cisplatin plus intravenous 5-fluorouracil chemotherapy for unresectable colorectal metastases.
1994
A multicenter, randomized Phase 2 study that compared patients, affected by colorectal liver metastases, who received intrahepatic arterial infusion with two different schedules of cisplatin, bolusvs. continuous infusion, and systemic 5-fluorouracil. PURPOSE: The aim of this study was to validate results of a previous Phase 2 trial on bolus cisplatin intrahepatic arterial infusion, which reported a 47 percent response rate and a 32 percent 4-year survival rate for Gennari's Stage 2 patients, with a high rate of neurologic, gastrointestinal, and hematologic toxicity. METHODS: One hundred nine patients were randomized in a Phase 2 study to receive cisplatin intrahepatic arterial infusion (24 …
Polarization-sensitive population trapping in an optically pumped laser
1994
Thermodynamic considerations of the grain size dependency of material properties
1994
Phase transitions which depend on grain size induce very interesting properties in materials such as zirconia or barium titanate. A new and rigorous thermodynamic treatment of this type of phase transition is proposed with consideration of the surface phenomena. An interpretation is given of the observed differences when the material—particularly BaTiO3—under consideration is a fine grain powder or is a fine grain ceramic.
Osteoblastic osteogenic sarcoma in a 13-month-old girl.
1994
Summary Osteosarcoma is exceptional in early periods of life. Therefore osteosarcomas involvingthe bones of the hand are extremely rare. We present a case of an osteogenic sarcoma involving the second metacarpal bone of a 13-month-old girl who has been remaining free of disease, after treatment — radial amputation and chemotherapy pre- and post-operative-, for a period of 10 years in the follow-up.
Etoposide Treatment in Recurrent Medulloblastoma
1994
Five consecutive patients with recurrent medulloblastoma received etoposide 120 mg/m2 for 5 to 7 days at 2 to 4-week intervals. Three patients with neuroaxis dissemination received additional intrathecal chemotherapy with methotrexate, cytosine arabinoside and prednisone. Toxicity consisted of alopecia and mild neutropenia. Complete response was registered in two patients, partial response in one. Median survival was 19 months with the 3 responders living 6, 30 and 60+ months. Etoposide seems to be an active agent in medulloblastoma.
Synthesis and herbicidal activity of isoxazole-substituted 1-aminoethylphosphonates and 1-hydroxyethylphosphonates
1994
Isoxazole‐substituted 1‐aminoethyl‐ and 1‐hydroxyethyiphosphonates were synthesized by a multi‐step procedure and were screened for herbicidal activity against Lepidium sativum L. and Cucumis sativus L. All the synthesized compounds exhibited notable herbicidal activity.
Quantitative bioluminescence imaging--a method for the detection of metabolite distributions in frozen tissues
1994
A novel technique allows for measurement of metabolite distributions in tissue cryosections at a microscopic level using bioluminescence, single photon imaging, and computerized image analysis. Metabolites, such as ATP, glucose and lactate are registered in absolute concentration units, and the respective images can be correlated with each other and with histological structures by specific algorithms. One striking difference between malignant tumors and normal tissue is the pronounced heterogeneity of metabolite distributions in malignancies contrasted by rather homogeneous patterns obtained in many normal organs. The heterogeneous distribution of metabolites in solid tumors reflects the ch…
Effect of Sublethal Concentrations of Pesticides on the Feeding Behavior of Daphnia magna
1994
Daphnia magna was exposed to sublethal levels (1/4, 1/2, and 2/3 LC50 and LC50) of endosulfan and diazinon to determine the effect of these pesticides on filtration and ingestion rates. The experiments were performed with the unicellular algae Nannochloris oculata in a density of 5 x 10(5) cells/ml. Prior to these experiments, the acute toxicity of both pesticides was evaluated to calculate the LC50s. The 24-hr LC50 values were 0.62 mg/liter and 0.9 microgram/liter for endosulfan and diazinon, respectively. Rates of filtration and ingestion declined with increasing toxicant concentrations after a short exposure of 5 hr. The effective concentration at which feeding rates were reduced to 50% …
How does a transition zone affect the electric field enhanced water dissociation in bipolar membranes?
1994
The changes in the electric field in the space charge regions and the corresponding effect on the water dissociation rate when a transition zone exists between the layers of a bipolar membrane are theoretically studied. A quasi-equilibrium approach based on the Poisson-Boltzmann equation for the space charge interfacial regions is used. The transition zone acts to decrease significantly the water dissociation rate. However, for realistic values of the thickness δ of the transition zone and provided that the ohmic drop over δ be small, this decrease in the dissociation rate is not very dependent on δ. The results obtained give theoretical support to some recent experimental findings.
Aneurysm surgery of patients in poor grade condition. Indications and experience
1994
Out of a total of 196 patients admitted with aneurysmal subarachnoid haemorrhage (SAH) to the neurological department in Mainz over a 42 month period, 48 patients (24.5%) were considered as grade IV or V on admission. Aneurysm surgery within 48 hours after SAH was performed in 56.3% of these patients, 2% were operated between day 3 and 7 and 16.6% were operated after day 7. 25% did not undergo operation because of severe neurological deficit and brain damage. The overall outcome according to the Glasgow outcome scale in the surgically treated group was full recovery in 11.1%, moderate disability in 16.7%, severe disability in 47.2%, vegetative state in 2.8% and death in 22.2%. All patients …
Brownian dynamics simulations of colloidal hard spheres. Effects of sample dimensionality on self-diffusion
1994
The self-diffusion coefficients of colloidal hard spheres were determined by Brownian dynamics (BD) computer simulations using a new efficient algorithm for treatment of the hard-sphere interactions. Calculations were done on an Apple PC type MacIIcx and on a Micro VAX 3000, considering samples in two and three dimensions at varying particle concentrations. Our results in three dimensions are compared with experimental results from our own group which were obtained by forced Rayleigh scattering (FRS), and with numerical results from a dynamical Monte Carlo simulation by Cichocki and Hinsen. Good agreement with the latter was found for particle volume fractions up to 0.40. Differences in the…
Stimulus Repetition Produces Automatic Facilitation in a Naming Task
1994
Repeated prime-target pairs in a lexical decision task showed improvement across 4 stimulus onset asynchronies for a single subject.
Berechnung der Fraktaldimension einiger poröser Feststoffe aus der Stickstoff-Adsorptionsisotherme
1994
Ultradian rhythms in avoidance behavior of DBA mice
1994
This study investigates ultradian rhythm in avoidance behavior of mice, which may constitute a basic rest activity cycle (BRAC). Reaction times (RTs) of an avoidance response to a visual warning stimulus that preceded an electric shock were measured by the use of a computer-controlled shuttle box. The male naive DBA mice were brought to a criterion of 98% correct responses in numerous training sessions. For each subject, all the temporal sequences of the RTs in the trials following achievement of the criterion were examined with discrete Fourier transform. Periodograms were obtained from three sessions for each of the two animals in the first experiment and from 15 subjects in the second ex…
Pietro Mengoli and the six-square problem
1994
The aim of this paper is to analyze a little known aspect of Pietro Mengoli's (1625-1686) mathematical activity: the difficulties he faced in trying to solve some problems in Diophantine analysis suggested by J. Ozanam. Mengoli's recently published correspondence reveals how he cherished his prestige as a scholar. At the same time, however, it also shows that his insufficient familiarity with algebraic methods prevented him, as well as other Italian mathematicians of his time, from solving the so-called “French” problems. Quite different was the approach used for the same problems by Leibniz, who, although likewise partially unsuccessful, demonstrated a deeper mathematical insight which led…
Blends from redox active liquid crystal ionomers and amorphous ionomers
1994
Abstract Biphasic blends (mixtures) of liquid crystal ionomers (prepared from ferrocene containing liquid crystal polymers by a redox reaction) and partially sulfonated polystyrene combine the constituent properties in a way, which is dependent on the measuring method. Polarizing microscopy shows homogenous textures similar to the pure liquid crystal polymer. Mechanical measurements show however the elastomeric behaviour of sulfonated polystyrene. The phase separated structure of these blends is proved by differential scanning calorimetry measurements.
Diagnosis of human immunodeficiency virus (HIV) infection: multicenter evaluation of a newly developed anti-HIV 1 and 2 enzyme immunoassay.
1994
A new anti-human immunodeficiency virus type 1 and 2 (anti-HIV 1 and 2) test is described. It uses recombinant p24 and peptides covering gp32, gp41, and gp120 to identify HIV-1 and HIV-2 infections. This test has been shown to be specific (99.5%) and sensitive (99.8%). In this respect, the assay was equal or superior to anti-HIV 1 and 2 tests run as references. The test was able to discriminate sera from patients with HIV infections from those from uninfected individuals with excellence; it also exerted high intra- and interassay precisions. The "modular" concept of the test allows the use of single components (gp32 or gp41) to separate between HIV-2 and HIV-1 infections, respectively.
Entrenamiento de los músculos ventilatorios
1994
Selection of optimal prophylactic aminoglycoside dosage in cancer patients: population pharmacokinetic approaches.
1994
We report an alternative dose-finding approach for the selection of optimal prophylactic aminoglycoside dosage in specific (sub)populations of patients. Relative a priori utility of several intervals of gentamicin or tobramycin (AMG) peak and trough serum levels were assigned by a group of pharmacokinetics experts, assuming prophylactic administration for laryngectomy interventions. A group of 27 adult patients, with normal renal function, undergoing elective surgery for laryngeal problems and treated prophylactically with gentamicin (80 mg t.i.d.) or tobramycin (100 mg t.i.d.) was studied. Two blood samples (peak and trough) were drawn at steady-state for AMG assay. Three different methods…
MECDAS/spl minus/a distributed data acquisition system for experiments at MAMI
1994
For coincidence experiments with the three-spectrometer setup at MAMI an experiment control and data acquisition system has been built and was put successfully into final operation in 1992. MECDAS is designed as a distributed system using communication via Ethernet and optical links. At the front end, VMEbus systems are used for real time purposes and direct hardware access via CAMAC, Fastbus or VMEbus. RISC workstations running UNIX are used for monitoring, data archiving and online and offline analysis of the experiment. MECDAS consists of several fixed programs and libraries, but large parts of readout and analysis can be configured by the user. Experiment specific configuration files ar…
A high resolution TDC subsystem
1994
A high resolution TDC subsystem was developed at the Institute for Nuclear Physics in Mainz. The TDC chip offers a time resolution of less than 300 ps and a programmable measurement range from O to 16 /spl mu/sec. The time measurement is done with a new, purely digital counting method. The chip can be operated in common start or common stop mode. In common start mode the chip is able to store up to 4 multiple hits per channel. The chip is used to build a transputer controlled subsystem for the measurement of the drift times of a vertical drift chamber. The design of the subsystem will be described and the first results from the tests of the prototype system will be presented. >
Bilateral reciprocal organisation in man: focus on IA interneurone
1994
The H reflex of flexor carpi radialis and radial-induced reciprocal inhibition were recorded in normal subjects during conditioning stimulation of the contralateral median or radial nerves. It was found that stimulation of the contralateral median nerve enhanced the degree of reciprocal inhibition exerted by the radial nerve on the median nerve, while contralateral radial nerve stimulation reduced the reciprocal inhibition exerted by the extensor on the flexor. In two subjects in which a pure extensor H reflex was recorded specular features were observed following contralateral median and radial stimulation. These findings are considered to be the electrophysiological manifestation of contr…
Cuerpos y mutaciones en el cine de ciencia-ficción durante los años cincuenta
1994
El cine de ciencia-ficción de los años cincuenta nos ofrece un testimonio ejemplar por su candidez de hasta dónde el patrón humano rige sin apenas deslices toda suerte de metamorfosis. La misma situación del género es en extremo curiosa: lejos de la imaginería gótica y romántica que alimentó las producciones Universal, también se distancia de las afecciones víricas, las prótesis teratológicas y la robótica de cuño informático que asaltan el cuerpo haciéndolo estallar en el moderno cine de terror.
The evolutionary genetics of the hobo transposable element in the Drosophila melanogaster complex.
1994
Hobo elements are a family of transposable elements found in Drosophila melanogaster and its three sibling species: D. simulans, D. mauritiana and D. sechellia. Studies in D. melanogaster have shown that hobo may be mobilized, and that the genetic effects of such mobilizations included the general features of hybrid dysgenesis: mutations, chromosomal rearrangements and gonadal dysgenis in F1 individuals. At the evolutionary level some hobo-hybridizing sequences have also been found in the other members of the melanogaster subgroup and in many members of the related montium subgroup. Surveys of older collected strains of D. melanogaster suggest that complete hobo elements were absent prior t…
Effect of titanium (IV) application on some enzymatic activities in several developing stages of red pepper plants
1994
Abstract The effect of two titanium (IV) compounds, titanium ascorbate and titanium chloride, on some enzymatic activities, such as catalase, peroxidase, lipoxygenase and nitrate reductase in seeds, embryos, and seedlings and adult plants of red pepper (Capsicum annuum L.), was studied. A stimulatory effect of titanium was observed for every iron‐depending enzyme studied at all developing stages as well as for nitrate reductase but only for whole plants. This occurs because Ti+3/Ti+4 catalizes the activity of iron and enhances iron‐dependent enzymes.
Einsatzmöglichkeiten der MR-Arthrographie bei Erkrankungen des Schultergelenkes
1994
In a prospective study possible indications for MR arthrography of the shoulder were evaluated. 37 patients were examined before and after intraarticular administration of a 2-mmolar solution of Gd-DTPA. MR arthrography was performed if there was no joint effusion and/or an uncertain finding concerning the rotator cuff or the capsulolabral complex on plain MR images. MR arthrography leads to a better demonstration of labrum pathology in 11/22 patients and to a superior delineation of the capsuloligamentous apparatus in 20/22 cases. In 9/15 patients with impingement lesions MR arthrography allowed a differentiation of severe tendinitis from partial and small full-thickness tears of the rotat…
Compact Hopf hypersurfaces of constant mean curvature in complex space forms
1994
We prove that every connected compact Hopf hypersurface of a complex space form , contained in a geodesic ball of radius strictly smaller than the injectivity radius of , having constant mean curvature and with if if λ < 0 is a geodesic sphere of .
A note on Fréchet and approximate subdifferentials of composite functions
1994
The aim of this note is to present in the reflexive Banach space setting a natural and simple proof of the formula of the approximate subdifferential of a composite function.
Normal Function of the mushroom body defect Gene of Drosophila Is Required for the Regulation of the Number and Proliferation of Neuroblasts
1994
In the developing central nervous system of Drosophila, proliferation follows a reproducible and well-described spatial and temporal pattern. This pattern involves a defined number and distribution of neural stem cells (neuroblasts), as well as a precisely regulated time course of division of these neuroblasts. We show that mutations in the mushroom body defect (mud) gene interfere with the regulation of this pattern in a rather specific manner. In the abdominal neuromeres a subset of neuroblasts prolongs the period of proliferation. Additional daughter cells persist into the imago. Similar defects are expressed in the anterior ventral nerve cord and in the lateral central brain region. In …
The Theory of the Flying Geese Pattern of Development and Its Interpretations
1994
An interpretation is made of Akamatsu Kaname's theory of the flying geese pattern of development, launched in Japan during the 1930s. This theory explains how an undeveloped country can become developed relatively quickly. The undeveloped country adopts suitable labour-intensive industries from more developed countries. It produces first for the home market, but starts to export as soon as the industries have grown strong enough. Initially, products are simple, crude and cheap, but gradually the level of quality is elevated. The procedure is repeated over and over again, leading to a rapid process of national economic development. In Japanese postwar industrial policy, certain industries w…
Amphetamine and Methamphetamine Determinations in Biological Samples by High Performance Liquid Chromatography. A Review
1994
Abstract This critical review shows the different high performance liquid chromatography methods proposed for amphetamine and methamphetamine determinations. It is directed mainly towards sample clean up and derivatizations steps, because of their significance in such determinations.
Arsenic content of Spanish cows' milk determined by dry ashing hydride generation atomic absorption spectrometry.
1994
SummaryThe arsenic content of cows' milk consumed in Spain was determined. A procedure using dry ashing hydride generation atomic absorption spectrometry was developed for the purpose. Experimental conditions for the destruction of organic matter were established and an interference study was carried out. The method developed has a detection limit of 0·1 ng/g, a relative SD of 5%, and a recovery (mean ± CSI) of 100 ± 4%. The accuracy of the method was checked by analysis of a certified sample of IAEA milk powder (mean ± CSI: certified, 4·85 ± 0·32 ng/g; found, 5·04 ± 0·81 ng/g). The proposed procedure was used to analyse cows' milk samples. The extremely low arsenic levels found do not pres…
Diastereoselective Functionalization of a Spherand‐Type Calixarene
1994
Condensation of 5,5'-di-tert-butyl-2,2'-dihydroxybiphenyl (1) with formaldehyde yields a cyclic trimer 2 (and tetramer 3) having three (four) methylene groups less than a calix[6]arene (calix[8]arene). Alkylation of the (flexible) trimer with ethyl bromoacetate gives exclusively the stereoisomer 4 with C 2 symmetry, while the isomer with D 3 symmetry is not observed. Two isomers 6a and 6b (C 2 and C 1 symmetry) are obtained by treatment with tert-butyl bromoacetate which both are converted by transesterification with methanol into the same hexamethyl ester 5 having C 2 symmetry. These results are rationalized by restricted rotation around Ar-Ar bonds for larger O-alkyl groups also around Ar…
Monosymptomatic presentation of type I Arnold-Chiari malformation: report of two cases.
1994
Two cases of type I ACM are described, one of which presented with dizziness in late childhood (case 1), the other with mild intention tremor in adulthood (case 2). Cerebellar ectopia should be considered in monosymptomatic patients even in the absence of other symptoms and signs of C.N.S. dysfunction. Magnetic resonance imaging of the craniocervical junction should be performed because it may be diagnostic for type I ACM.