Showing papers by "David W. Johnson published in 1987"
TL;DR: Because of the apparent restriction of adipsin synthesis to tissues highly active in lipid metabolism, its presence in serum, and its modulation in altered metabolic states, this molecule may play a previously unrecognized role in systemic lipid metabolism or energy balance.
Abstract: Adipsin is a serine protease homolog whose primary structure was predicted from the nucleotide sequence of a differentiation-dependent adipocyte messenger RNA. Immunoblots probed with antisera to synthetic peptides identify two forms of adipsin that are synthesized and secreted by 3T3 adipocytes. These proteins of 44 and 37 kilodaltons are converted to 25.5 kilodaltons by enzymatic deglycosylation. Although adipsin is principally synthesized in adipose tissue, it is also produced by sciatic nerve and is found in the bloodstream. Because of the apparent restriction of adipsin synthesis to tissues highly active in lipid metabolism, its presence in serum, and its modulation in altered metabolic states, this molecule may play a previously unrecognized role in systemic lipid metabolism or energy balance.
373 citations
TL;DR: Direct evidence that some mammalian retinal ganglion cells contain substance P-like peptides is reported and strongly suggests that, in the rabbit, substance P (or related tachykinins) may be a transmitter or modulator in a specific population or populations of retinal Ganglion Cells.
Abstract: Substance P-immunoreactive retinal ganglion cells and their central axon terminals in the rabbit
137 citations
Journal Article•
117 citations
TL;DR: In this article, a method is described to assign the positional series of methylene interrupted polyenoic acids, in complex mixtures, isolated from hydrolysed lipid extracts, in a simple comparison of the intensities of three ions of m/z 108, 150 and 192.
Abstract: A method is described to assign the positional series of methylene interrupted polyenoic acids, in complex mixtures, isolated from hydrolysed lipid extracts. It entails a simple comparison of the intensities of three ions of m/z 108, 150 and 192.
79 citations
TL;DR: Mass spectral analysis has shown the very long chain fatty acids found in ram spermatozoa to have a carbon chain length of between 28 and 34, with between four and six double bonds, and to belong predominantly to the n-3 series.
Abstract: The high levels of very long chain fatty acids found in ram spermatozoa are located almost exclusively in one of two separable species of sphingomyelin. Mass spectral analysis, including fast atom bombardment of the purified sphingomyelin, has shown the fatty acids to have a carbon chain length of between 28 and 34, with between four and six double bonds, and to belong predominantly to the n-3 series.
64 citations
TL;DR: Patterns of individual differences were found which support the conclusion that individual differences in auditory performance are, in part, a function of patterns of independent abilities.
Abstract: Twenty-eight audiometrically normal adult listeners were given a variety of auditory tests, ranging from quiet and masked thresholds through the discrimination of simple and moderately complex temporal patterns. Test-retest reliability was good. Individual differences persisted on a variety of psychoacoustic tasks following a period of training using adaptive threshold-tracking methods, and with trial-by-trial feedback. Large individual differences in performance on temporal-sequence-discrimination tasks suggest that this form of temporal processing may be of clinical significance. In addition, high correlations were obtained within given classes of tests (as, between all tests of frequency discrimination) and between certain classes of tests (as, between tests of frequency discrimination and those of sequence discrimination). Patterns of individual differences were found which support the conclusion that individual differences in auditory performance are, in part, a function of patterns of independent abilities.
47 citations
TL;DR: In this paper, a summary of plasma-material interactions which influence the operation of TFTR with high current (≤ 2.2 MA) ohmically heated, and high power (∼ 10 MW) neutral-beam heated plasmas is presented.
46 citations
TL;DR: Sera from 12 patients with amyotrophic lateral sclerosis and 18 controls were screened for antineural antibodies using immunoblotting, and immunohistochemistry suggested antibody activity was directed at least in part to neurofilaments.
Abstract: Sera from 12 patients with amyotrophic lateral sclerosis (ALS) and 18 controls were screened for antineural antibodies using immunoblotting. No consistent differences were detected between ALS patients and controls, although antibodies to 52,000- and 70,000-dalton proteins in mouse spinal cord were somewhat more common in ALS sera. Antibodies to a protein of approximately 150,000 to 200,000 daltons were also evident. The 70,000- and 52,000-dalton proteins were detected in brain, cerebellum, and liver as well as spinal cord. Immunohistochemistry suggested antibody activity was directed at least in part to neurofilaments. While the antibodies to the 52,000- and 70,000-dalton proteins were more common in ALS than control sera ( p
TL;DR: In this paper, a high-resolution crystal spectrometer was used for simultaneous observation of the helium-like resonance line, the intercombination and forbidden lines, and all the associated satellites due to transitions 1{s}^{2}$nl-1s2l'nl'' with n\ensuremath{\ge}2.
Abstract: Spectra of heliumlike nickel, Ni xxvii, have been observed from Tokamak Fusion Test Reactor (TFTR) plasmas with a high-resolution crystal spectrometer. The experimental arrangement permits simultaneous observation of the heliumlike resonance line, the intercombination and forbidden lines, and all the associated satellites due to transitions 1${s}^{2}$nl-1s2l'nl'' with n\ensuremath{\ge}2. Relative wavelengths and line intensities can thus be determined very accurately. The observed spectral data are in good agreement with results from the present Hartree-Fock-Slater atomic model calculations and predictions from the Z-expansion method.
TL;DR: It is postulated that the polyenoic VLCFA may play an important role in normal brain and accumulate in Zellweger syndrome brain because of a deficiency in the peroxisomal beta-oxidation pathway, although a possible peroxISomal role in the control of carbon-chain elongation cannot be discounted.
Abstract: The polyenoic fatty acids with carbon chain lengths from 26 to 38 (very-long-chain fatty acids, VLCFA) previously detected in abnormal amounts in Zellweger syndrome brain have been shown to be n-6 derivatives and therefore probably derived by chain elongation of shorter-chain n-6 fatty acids such as linoleic acid and arachidonic acid. Polyenoic VLCFA are also present in Zellweger syndrome liver, but this tissue differs significantly from brain in that the saturated and mono-unsaturated derivatives are the major VLCFA. Zellweger syndrome brain polyenoic VLCFA are present in the neutral lipids predominantly in cholesterol esters, with smaller amounts in the non-esterified fatty acid and triacylglycerol fractions. These fatty acids are barely detectable in any of the major phospholipids, but are present in significant amounts in an unidentified minor phospholipid. The polyenoic VLCFA composition of this lipid differs markedly from that observed for all other lipids, as it contains high proportions of pentaenoic and hexaenoic fatty acids with 34, 36 and 38 carbon atoms. A polar lipid with the chromatographic properties in normal brain contains similar fatty acids. It is postulated that the polyenoic VLCFA may play an important role in normal brain and accumulate in Zellweger syndrome brain because of a deficiency in the peroxisomal beta-oxidation pathway, although a possible peroxisomal role in the control of carbon-chain elongation cannot be discounted.
TL;DR: Results indicate that a major mechanism of chloride entry into CSF is sodium-coupled chloride transport, which is important to CSF acid-base balance.
Abstract: Movement of chloride from blood to cerebrospinal fluid (CSF) is one of the factors that may be involved in regulation of CSF (Cl-), which is important to CSF acid-base balance. We made quantitative measurements of the unidirectional flux of radiolabeled chloride between blood and CSF in anesthetized dogs, using /sup 38/Cl, a short-lived isotope (half-life 37.3 min). This allowed multiple studies to be performed in a given animal. A three-compartment model for the blood, CSF, brain extracellular fluid, and ventriculocisternal perfusion system was used to determine the flux rate. With normocapnia, the flux was 0.01.1 min-1. The influx could be reproducibly measured for three separate determinations in the same animal over a period of 6 h, being 98 +/- 6% of the control first run on the second run and 113 +/- 6% on the third. Furosemide and bumetanide, inhibitors of sodium-coupled chloride movement, lowered the flux to 43 +/- 3% and 55 +/- 6% of control, respectively. The combination of hypercapnia and furosemide lowered the influx to 63 +/- 9% of control. These results indicate that a major mechanism of chloride entry into CSF is sodium-coupled chloride transport.
TL;DR: In this article, the ratio of x-ray fluxes transmitted through two different absorber foils was used to measure the electron temperature along 10 to 30 chords spaced at 5-12.5 cm with a time resolution of less than 100 µm.
Abstract: Absorber foils have been installed in the TFTR X-Ray Imaging System to permit measurement of the electron temperature along 10 to 30 chords spaced at 5-12.5 cm with a time resolution of less than 100 ..mu..s. The technique uses the ratio of x-ray fluxes transmitted through two different foils. The ratio depends mainly on electron temperature. Simulations show that strong impurity line radiation can distort this ratio. To correct for these effects, special beryllium-scandium filters are employed to select the line-free region between 2 and 4.5 keV. Other filter pairs allow corrections for Fe L and Ni L line radiation as well as Ti K and Ni K emission. Good accuracy is also obtained with simple beryllium filters, provided that impurity corrections are incorporated in the analysis, taking line intensities from the x-ray pulse-height analysis diagnostic. A description of modeling calculations and a comparison of temperature values from this diagnostic with data from the x-ray pulse height analysis, the electron cyclotron emission, and the Thomson scattering diagnostics are presented. Several applications of the absorber foil electron temperature diagnostic on TFTR are discussed.
TL;DR: In this article, the properties of TFTR ohmic detached plasmas with a range of plasma densities at two different plasma currents were investigated and compared with two different TFTR currents.
TL;DR: Tissue fractionation studies indicate that poliovirus binding sites are enriched in synaptosomes, the subfraction of central nervous system gray matter tissue rich in synaptic endings, which may be an important factor in the motor tropism of this virus.
Abstract: Poliovirus is a neurotropic virus that selectively infects human motoneurons in vivo. The basis for the specificity of this infection is not fully understood. It has been suggested that this tropism occurs because motoneurons are the only neurons to express poliovirus receptors. We have examined this hypothesis by measuring the binding of 125I-labeled poliovirus type 1 to neural tissues. With this assay we have detected highly specific binding sites in human but not rodent neural tissue. Regional assays of binding in human central nervous system homogenates demonstrate that binding sites are not confined to motoneurons. Rather, they are widely distributed throughout the human neuraxis. Particularly in the forebrain, binding is more abundant in gray than white matter. For this reason, we performed tissue fractionation studies which indicate that poliovirus binding sites are enriched in synaptosomes, the subfraction of central nervous system gray matter tissue rich in synaptic endings. The preferential expression of poliovirus binding sites in synaptic endings may be an important factor in the motor tropism of this virus, inasmuch as the major category of neurons with synaptic endings outside the central nervous system are motoneurons; thus, particles of virus may preferentially bind to this cell type during poliovirus viremia.
TL;DR: In this article, new long-pulse ion sources have been employed to extend the neutral beam pulse on TFTR from 0.5 sec to 2.0 sec. This made it possible to study the long-term evolution of supershots at constant current and to perform experiments in which the plasma current was ramped up during the heating pulse.
Abstract: New long-pulse ion sources have been employed to extend the neutral beam pulse on TFTR from 0.5 sec to 2.0 sec. This made it possible to study the long-term evolution of supershots at constant current and to perform experiments in which the plasma current was ramped up during the heating pulse. Experiments were conducted with co and counter injection as well as with nearly balanced injection of deuterium beams up to a total power of 20 MW. The best results, i.e., central ion temperatures Tio > 25 keV and neo τE Tio values of 3 × 1020 keV sec m-3, were obtained with nearly balanced injection. The central toroidal plasma rotation velocity scales in a linear-offset fashion with beam power and density. The scaling of the inferred global momentum confinement time with plasma parameters is inconsistent with the predictions of the neoclassical theory of gyroviscous damping. An interesting plasma regime with properties similar to the H-mode has been observed for limiter plasmas with edge qa just above 3 and 2.5.
03 Apr 1987-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: The neutral beam injection experiment on TFTR has now been underway for over two years, during which time we have injected as much as about 20 MW of beam power at energies up to 110 keV as mentioned in this paper.
Abstract: The neutral beam injection experiment on TFTR has now been underway for over two years, during which time we have injected as much as about 20 MW of beam power at energies up to 110 keV. We have obtained qualitative evidence of direct current drive by the injected beam ions. Recently we have produced plasmas in which the energy confinement time, βp, neutron emission, stored energy (both total and electron), and ion temperature exhibit a pronounced enhancement over previous behavior. Under these conditions we have obtained preliminary indications that significant bootstrap current is being driven. Operation will continue with new sources with which we should be able to increase the beam pulse length fourfold.
TL;DR: Cooperative learning is the only instructional strategy congruent with the goals of nutrition education and when cooperative learning is implemented effectively, long-term modifications of nutrition knowledge, attitudes and behavior result.
Abstract: There are three ways in which student-student interaction may be organized for nutrition education. Of the three, cooperation is the only instructional strategy congruent with the goals of nutrition education. The essential elements of cooperative learning and the specific actions teachers need to take to implement it are presented. When cooperative learning is implemented effectively, long-term modifications of nutrition knowledge, attitudes and behavior result. Nutrition education classes will more successfully fulfill their purposes when cooperative learning is primarily used.
29 Jun 1987-Philosophical transactions - Royal Society. Mathematical, physical and engineering sciences
TL;DR: In this paper, the TFTR tokamak has reached its original machine-design specifications (I p = 2.5 MA and B T = 5.2 T).
Abstract: Recent experiments on TFTR have extended the operating regime of TFTR in both ohmic- and neutral-beam -heated discharges. The TFTR tokamak has reached its original machine-design specifications ( I p = 2.5 MA and B T = 5.2 T). Initial neutral-beam -heating experiments used up to 6.3 MW of deuterium beams. With the recent installation of two additional beamlines, the power has been increased up to 11 MW. A deuterium pellet injector was used to increase the central density to 2.5 x 10 20 m -3 in high-current discharges. At the opposite extreme, by operating at low plasm a current ( I p ~ 0.8 MA) and low density ( n e~ 1 x 10 19 m -3 ), high ion temperatures (9 + 2 keV) and rotation speeds (7 x 10 5 m s -1 ) have been achieved during injection. In addition, plasma-compression experiments have demonstrated acceleration of beam ions from 82 to 150 keV, in accord with expectations. The wide operating range of TFTR, together with an extensive set of diagnostics and a flexible control system, has facilitated transport and scaling studies of both ohmic- and neutral-beam -heated discharges. The result of these confinement studies are presented.