Showing papers by "Tulane University published in 1982"
TL;DR: The Hohenberg-Kohn theorem was extended to fractional electron number for an isolated open system described by a statistical mixture in this article, and the curve of lowest average energy was found to be a series of straight line segments with slope discontinuities at integral $N.
Abstract: The Hohenberg-Kohn theorem is extended to fractional electron number $N$, for an isolated open system described by a statistical mixture. The curve of lowest average energy ${E}_{N}$ versus $N$ is found to be a series of straight line segments with slope discontinuities at integral $N$. As $N$ increases through an integer $M$, the chemical potential and the highest occupied Kohn-Sham orbital energy both jump from ${E}_{M}\ensuremath{-}{E}_{M\ensuremath{-}1}$ to ${E}_{M+1}\ensuremath{-}{E}_{M}$. The exchange-correlation potential $\frac{\ensuremath{\delta}{E}_{\mathrm{xc}}}{\ensuremath{\delta}n(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})}$ jumps by the same constant, and $\frac{{\mathrm{lim}}_{r\ensuremath{\rightarrow}\ensuremath{\infty}}\ensuremath{\delta}{E}_{\mathrm{xc}}}{\ensuremath{\delta}n(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})}g~0$.
2,427 citations
TL;DR: Analysis of the total base composition of DNA from seven different normal human tissues and eight different types of homogeneous human cell populations revealed considerable tissue-specific and cell-specific differences in the extent of methylation of cytosine residues.
Abstract: Analysis of the total base composition of DNA from seven different normal human tissues and eight different types of homogeneous human cell populations revealed considerable tissue-specific and cell-specific differences in the extent of methylation of cytosine residues. The two most highly methylated DNAs were from thymus and brain with 1.00 and 0.98 mole percent 5-methylcytosine (m5C), respectively. The two least methylated DNAs from in vivo sources were placental DNA and sperm DNA, which had 0.76 and 0.84 mole percent m5C, respectively. The differences between these two groups of samples were significant with p less than 0.01. The m5C content of DNA from six human cell lines or strains ranged from 0.57 to 0.85 mole percent. The major and minor base composition of DNA fractionated by reassociation kinetics was also determined. The distribution of m5C among these fractions showed little or no variation with tissue or cell type with the possible exception of sperm DNA. In each case, nonrepetitive DNA sequences were hypomethylated compared to unfractionated DNA.
1,081 citations
TL;DR: Two critical properties possessed by ordinary relational databases are proven to exist in the fuzzy relational structure, which means no two tuples have identical interpretations, and each relational operation has a unique result.
623 citations
TL;DR: In this article, the Kohn-Sham effective potential is defined such that its sum of lowest orbital energies equals the true interacting ground-state energy, which is the most invariant with respect to changes in the one-body potential of the true Hamiltonian.
Abstract: By utilizing the knowledge that a Hamiltonian is a unique functional of its ground-state density, the following fundamental connections between densities and Hamiltonians are revealed: Given that ${\ensuremath{\rho}}_{\ensuremath{\alpha}}, {\ensuremath{\rho}}_{\ensuremath{\beta}},\dots{},{\ensuremath{\rho}}_{\ensuremath{\omega}}$ are ground-level densities for interacting or noninteracting Hamiltonians ${H}_{1}, {H}_{2},\dots{},{H}_{M}$ ($M$ arbitrarily large) with local potentials ${v}_{1}$,${v}_{2}$,$\dots{}$,${v}_{M}$, but given that we do not know which $\ensuremath{\rho}$ belongs with which $H$, the correct mapping is possible and is obtained by minimizing $\ensuremath{\int}d\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}} [{v}_{1}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}}){\ensuremath{\rho}}_{\ensuremath{\alpha}}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})+{v}_{2}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}}){\ensuremath{\rho}}_{\ensuremath{\beta}}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})+\ensuremath{\cdots}{v}_{M}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}}){\ensuremath{\rho}}_{\ensuremath{\omega}}(\stackrel{\ensuremath{\rightarrow}}{\mathrm{r}})]$ with respect to optimum permutations of the $\ensuremath{\rho}$'s among the $v$'s. A tight rigorous bound connects a density to its interacting ground-state energy via the one-body potential of the interacting system and the Kohn-Sham effective one-body potential of the auxiliary noninteracting system. A modified Kohn-Sham effective potential is defined such that its sum of lowest orbital energies equals the true interacting ground-state energy. Moreover, of all those effective potentials which differ by additive constants and which yield the true interacting ground-state density, this modified effective potential is the most invariant with respect to changes in the one-body potential of the true Hamiltonian. With the exception of the occurrence of certain linear dependencies, $a$ density will not generally be associated with any ground-state wave function (is not wave function $v$ representable) if that density can be generated by a special linear combination of three or more densities that arise from a common set of degenerate ground-state wave functions. Applicability of the "constrained search" approach to density-functional theory is emphasized for non-$v$-representable as well as for $v$-representable densities. In fact, a particular constrained ensemble search is revealed which provides a general sufficient condition for non-$v$ representability by a wave function. The possible appearance of noninteger occupation numbers is discussed in connection with the existence of non-$v$ representability for some Kohn-Sham noninteracting systems.
584 citations
TL;DR: The widespread but selective distribution of neurons containing CRF-like immunoreactivity supports the neuroendocrine role of this peptide and suggests that CRF, similarly to other neuropeptides, may also function as a neuromodulator throughout the brain.
Abstract: The immunocytochemical localization of neurons containing the 41 amino acid peptide corticotropin-releasing factor (CRF) in the rat brain is described. The detection of CRF-like immunoreactivity in neurons was facilitated by colchicine pretreatment of the rats and by silver intensification of the diaminobenzidine end-product. The presence of immunoreactive CRF in perikarya, neuronal processes, and terminals in all major subdivisions of the rat brain is demonstrated. Aggregates of CRF-immunoreactive perikarya are found in the paraventricular, supraoptic, medial and periventricular preoptic, and premammillary nuclei of the hypothalamus, the bed nuclei of the stria terminalis and of the anterior commissure, the medial septal nucleus, the nucleus accumbens, the central amygdaloid nucleus, the olfactory bulb, the locus ceruleus, the parabrachial nucleus, the superior and inferior colliculus, and the medial vestibular nucleus. A few scattered perikarya with CRF-like immunoreactivity are present along the paraventriculo-infundibular pathway, in the anterior hypothalamus, the cerebral cortex, the hippocampus, and the periaqueductal gray of the mesencephalon and pons. Processes with CRF-like immunoreactivity are present in all of the above areas as well as in the cerebellum. The densest accumulation of CRF-immunoreactive terminals is seen in the external zone of the median eminence, with some immunoreactive CRF also present in the internal zone. The widespread but selective distribution of neurons containing CRF-like immunoreactivity supports the neuroendocrine role of this peptide and suggests that CRF, similarly to other neuropeptides, may also function as a neuromodulator throughout the brain.
410 citations
TL;DR: Measurements of transmembrane potential indicate that transient extracellular electrical fields (ephaptic interactions) contribute to the observed synchrony; electrotonic coupling and changes in the concentration ofextracellular ions may also contribute.
Abstract: Extracellular field potential and intracellular recordings from neurons in rat hippocampus show that, even with synaptic transmission blocked, antidromic electrical stimuli can trigger afterdischarges of up to 9 seconds duration; during these discharges action potentials of a single neuron were synchronized with extracellularly recorded population spikes. Apparently mechanisms other than recurrent chemical synapses can synchronize and recruit epileptiform events. Measurements of transmembrane potential indicate that transient extracellular electrical fields (ephaptic interactions) contribute to the observed synchrony; electrotonic coupling and changes in the concentration of extracellular ions may also contribute.
358 citations
TL;DR: The results suggest that dynorphin occurs in neuronal systems that are immunocytochemically distinct from those containing other opioid peptides.
313 citations
TL;DR: It appears that the brain contains at least three separate opioid neuronal networks: an enkephalin family with components similar to those found in the adrenal, a beta-endorphin family, and a dynorphinfamily.
Abstract: A study of the anatomical distribution of the endogenous opioid dynorphin in rat brain showed that the peptide is localized in a widespread system with multiple cell groups and projections. This network is revealed by the use of multiple antiserums against dynorphin and can be distinguished from the system containing methionine-enkephalin and leucine-enkephalin, which is mapped by the use of antiserums against the enkephalins and biosynthetically related peptides in the adrenal. It thus appears that the brain contains at least three separate opioid neuronal networks: an enkephalin family with components similar to those found in the adrenal, a beta-endorphin family, and a dynorphin family.
264 citations
TL;DR: In this paper, the authors introduced a new version of the vortex method for three-dimensional, incompressible flows and proved that it converges to arbitrarily high order accuracy, provided they assume the consistency of a discrete approximation to the Biot-Savart Law.
Abstract: In an earlier paper the authors introduced a new version of the vortex method for three-dimensional, incompressible flows and proved that it converges to arbitrarily high order accuracy, provided we assume the consistency of a discrete approximation to the Biot-Savart Law. We prove this consistency statement here, and also derive substantially sharper results for two-dimensional flows. A complete, simplified proof of convergence in two dimensions is included.
258 citations
TL;DR: The data reported in this study indicate that purified guanylate cyclase binds heme and the latter is required for enzyme activation by NO and nitroso compounds.
255 citations
TL;DR: A new class of "crude" three-dimensional vortex methods is constructed and it is proved that these methods are stable and convergent, and can even have arbitrarily high order accuracy without being more expensive than other "crud" versions of the vortex algorithm.
Abstract: Recently several different approaches have been developed for the simulation of three-dimensional incompressible fluid flows using vortex methods. Some versions use detailed tracking of vortex filament structures and often local curvatures of these filaments, while other methods require only crude information, such as the vortex blobs of the two-dimensional case. Can such "crude" algorithms accurately account for vortex stretching and converge? We answer this question affirmatively by constructing a new class of "crude" three-dimensional vortex methods and then proving that these methods are stable and convergent, and can even have arbitrarily high order accuracy without being more expensive than other "crude" versions of the vortex algorithm.
TL;DR: The results suggest that a second biologically active site within the dynorphin sequence is capable of quite potent but nonopiate effects.
Abstract: Intracerebroventricular administration of dynorphin produced potent and long-lasting effects on motor function and the electroencephalogram in rats. In addition, local iontophoretic or pressure ejection of dynorphin consistently inhibited hippocampal unit activity. None of these effects were significantly affected by naloxone even at high doses. Moreover, a fragment of dynorphin that failed to displace any of a number of tritiated narcotics from rat brain homogenates produced similar effects on these physiological measures in vivo. On the basis of a variety of criteria for "opiate action," the results suggest that a second biologically active site within the dynorphin sequence is capable of quite potent but nonopiate effects.
TL;DR: The dispersion of LHRH cells over many nuclear groups may allow for the integration of afferents from divergent regions of the neuraxis to mediate both tonic and phasic gonadotropin secretion in the rat.
Abstract: The purpose of this study was to determine the distribution of luteinizing hormone-releasing hormone (LHRH) cells and pathways projecting to the median eminence and organum vasculosum of the lamina terminalis in the hypothalamus of the rat. Immunopositive LHRH was detected by the PAP method of immunocytochemistry on vibratome sections without embedding. Female rats were ovariectomized and treated with estradiol benzoate or implanted with estradiol capsules prior to sacrifice in order to minimize variations in LH and ultimately to maximize hypothalamic LHRH content. Immunoreactive LHRH perikarya are diffusely aggregated across several nuclear groups: nucleus of the vertical limb of the diagonal band of Broca, medial septal nucleus, medians preoptic nucleus, rostral and medial preoptic areas, anterior hypothalamic area, and lateral and basal hypothalamic areas. The aggregate of LHRH cells when projected upon a horizontal plane resembles the form of a V bisected by the third ventricle. The apex of the V is directed rostrally toward the midline nuclear groups whereas the ends of the V incline ventrally toward the base of the brain and the median eminence. The majority of LHRH cells are in the rostral portion of the V in preoptic and anterior hypothalamic areas. Few cells are present in the basal hypothalamus. The processes of LHRH cells form two diffuse fiber systems which are separated by the midline hypothalamic nuclei over most of their course and converge in the basal hypothalamus close to the median eminence. The more lateral fiber system forms part of the medial forebrain bundle, while the periventricular system is associated with the wall of the third ventricle. The dispersion of LHRH cells over many nuclear groups may allow for the integration of afferents from divergent regions of the neuraxis to mediate both tonic and phasic gonadotropin secretion in the rat.
TL;DR: The presence of synthetic ovine corticotropin-releasing factor leads to a rapid and marked stimulation of adenosine 3', 5'-monophosphate accumulation in an enriched population of rat pituitary corticotrophs in primary culture, suggesting changes in the intracellular concentration of the cyclic nucleotide coincide with or precede the secretion of adrenocorticotropic hormone in response to corticotropic factor.
Abstract: The presence of synthetic ovine corticotropin-releasing factor leads to a rapid and marked stimulation of adenosine 3', 5'-monophosphate accumulation in an enriched population of rat pituitary corticotrophs in primary culture. The increase, observed as early as 60 seconds after the addition of corticotropin-releasing factor, suggests that changes in the intracellular concentration of the cyclic nucleotide coincide with or precede the secretion of adrenocorticotropic hormone in response to corticotropin-releasing factor.
TL;DR: A synthetic preparation of the 41-aminoacid-residue peptide recently isolated from ovine hypothalami and characterised corticotropin-releasing factor (CRF) suggests that it, or a related peptide, may be a CRF in man, and it may provide the basis for a new clinical test of pituitary ACTH reserve.
TL;DR: The authors posit a model in which it is in the interest of suppliers of a collectively provided good not to generate full information to voters about outside aid and suggest that voters are very poorly informed about outside grants.
TL;DR: In this paper, it is shown that the gradient expansion of the Hartree-Fock exchange energy with Kohn-Sham orbitals converges with respect to a priori coefficient of Sham.
Abstract: It is well known that the density-gradient expansion of the Hartree-Fock exchange energy for the bare-Coulomb interaction contains divergent terms of order ${e}^{4}$ where $e$ is the electronic charge. We argue that the exchange energy evaluated with Kohn-Sham orbitals (i.e., those derived from a local effective potential) is purely of order ${e}^{2}$ and therefore its gradient expansion is well defined. This density-gradient expansion, with the a priori coefficient of Sham, is shown to converge by comparison with numerically refined values for the exact exchange energy of a metal surface in the linear-potential model. As the electron density profile becomes more slowly varying, the relative error of the zeroth-order (local-density) term tends to zero. We present here the first demonstration that, in addition, the absolute error is increasingly canceled by the second-order (gradient) term. Like the gradient expansion for the kinetic energy but unlike the one for correlation, the gradient expansion for exchange gives useful results even for "physical" surface profiles. One- and many-electron atoms are also discussed. It is observed that, as the atomic number increases, the relative errors of the local-density and gradient-expansion approximations decrease in magnitude, but the gradient term corrects only a small fraction of the error of the local-density approximation. This is a consequence of the fact that the convergence condition $\frac{|\ensuremath{
abla}n|}{2}{k}_{F}n\ensuremath{\lesssim}1$ is increasingly satisfied as the atomic number increases but the second convergence condition $\frac{|{\ensuremath{
abla}}^{2}n|}{2{k}_{F}|\ensuremath{
abla}n|}\ensuremath{\ll}1$ is not so well satisfied.
TL;DR: In this article, the relativistic effects of the ground-state monatomic negative ions with $Zl86$ were calculated using the selfinteraction correction (SIC) to the local spin-density approximation (LSD) for exchange and correlation.
Abstract: The extra-electron binding energies of the ground-state monatomic negative ions with $Zl86$ are calculated using the self-interaction correction (SIC) to the local spin-density approximation (LSD) for exchange and correlation. The results agree reasonably with experiment, and the errors reflect the familiar "interconfigurational energy error" common to LSD and SIC. Some of the rare earths, e.g., Ce and possibly Gd, are predicted to form stable negative ions. In addition we have the following: (1) Relativistic (other than spin-orbit) contributions to the electron affinities are included and discussed. In Au the relativistic effects boost the calculated affinity from 1.5 to 2.5 eV. (2) The doubly negative ions ${\mathrm{O}}^{2\ensuremath{-}}$ and ${\mathrm{Te}}^{2\ensuremath{-}}$ are predicted to have no stable ground state. (3) Electron affinities are calculated for a few excited atomic states. (4) The calculated ground-state densities $n(r)$ of all the neutral atoms and negative ions are monotonically decreasing functions of $r$. (5) Corrections to the random-phase-approximation electron-gas correlation energy are shown to cancel out of SIC calculations for atoms.
TL;DR: It is suggested that genetic control of acquired resistance to C. albicans may not be associated with the H-2 complex and resistance to systemic candidiasis is dependent upon a combination of innate factors, predominately an intact complement system, and the acquisition of an immune response, most likely of a cell-mediated type.
Abstract: Mice from six genetically distinct strains were examined for their immune responses to Candida albicans in in vitro and in vivo assays, and naive mice and mice immunized with the fungus were challenged intravenously with three different doses of C. albicans to determine differences in susceptibility. Naive mice from the six groups showed substantial differences in resistance to challenge based on mortalities and quantitative cultures of kidneys, with mice from strains C57BL/6J and BALB/cByJ showing the most resistance; mice from strains A/J, C3H/HeJ, and CBA/J showing moderate susceptibility; and mice from strain DBA/2J showing the highest degree of susceptibility to challenge. Unimmunized mice from strains C57BL/6J and BALB/cByJ did not produce detectable levels of Candida-specific antibody by the end of the 28-day observation period when challenged intravenously, but the other strains did. Immunized mice showed a degree of protection to challenge, with all groups except mice from strain BALB/cByJ showing a reduction of two to three log units in the level of colonization in their kidneys and all strains producing significant levels of antibody. Additionally, the immunized mice of all strains developed substantial levels of delayed-type hypersensitivity and demonstrated nearly identical lymphocyte proliferative responses to Candida antigens. The results indicate that resistance to systemic candidiasis is dependent upon a combination of innate factors, predominately an intact complement system, and the acquisition of an immune response, most likely of a cell-mediated type. Additionally, the findings suggest that genetic control of acquired resistance to C. albicans may not be associated with the H-2 complex.
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TL;DR: The authors' recent experiences with 5 such cases has prompted us to advocate immediate operative intervention for fracture of the penis, and a previously unreported complication of nonsurgical management is included.
TL;DR: The drug seems quite selective: no changes in levels of other neuropeptides — LH-RH, vasopressin, enkephalin, VIP, CCK — were observed in the same animals.
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TL;DR: Zinc has long been recognized as an essential constituent of various tissues, and many clinical conditions and dietary factors reduce the absorption or the biological availability of zinc, and lead to zinc deficiency which produces structural and functional alterations in many organ systems.
TL;DR: The reactions at physiological pH and elevated temperature suggest that deamination of 5-methylcytosine residues may yield a significant portion of spontaneous mutations in vivo, especially in view of the lack of thymine-specific mismatch repair systems with specificity and efficiency comparable to that of uracil excision repair systems.
TL;DR: In this article, the authors presented a cryosurgical technic for treatment of actinic keratoses and the cure rates of 1,018 lesions with a follow-up of at least 1 year.
Abstract: Cryosurgery is a commonly used modality for treatment of benign and malignant lesions in dermatology. Although cryosurgery has been used for treatment of actinic keratoses, to our knowledge there have been no published reports on actual cure rates. This article presents a cryosurgical technic for treatment of actinic keratoses and the cure rates of 1,018 lesions with a follow-up of at least 1 year.
TL;DR: Evidence is provided that endogenous somatostatin exerts local tonic control of pituitary and pancreatic secretions and catalytic hydrogenation of the protected peptide intermediate unexpectedly gave cyclo [7-aminoheptanoyl-Phe-D-Trp-Lys-Thr(Bzl)] in which the benzyl protecting group on Thr could not be removed even upon prolonged treatment under standard conditions.
TL;DR: Administration of synthetic ovine corticotropin-releasing factor led to rapid, parallel increases in adrenocorticotropic hormone and alpha-melanocyte-stimulating hormone concentrations in rat plasma, demonstrating that corticotropic factor is a potent stimulator not only of corticotrophs of the anterior pituitary gland but also of peptide secretion from the intermediate lobe.
Abstract: Administration of synthetic ovine corticotropin-releasing factor led to rapid, parallel increases in adrenocorticotropin and alpha-melanocyte-stimulating hormone concentrations in rat plasma. Prior treatment with dexamethasone almost completely blocked the adrenocorticotropin response but not the increase in melanocyte-stimulating hormone. These data demonstrate that corticotropin-releasing factor is a potent stimulator not only of adrenocorticotropin secretion from the corticotrophs of the anterior pituitary gland but also of peptide secretion from the intermediate lobe. Such data suggest that melanocyte-stimulating hormone and beta-endorphin play a role in the physiological response to stress.
TL;DR: A population of neuronal cell bodies and their fiber pathways have been elucidated within the ovine hypothalamus and the immunoreactive neurons were located in the anterior and dorsal hypothalamus interspersed throughout the paraventricular nucleus.
TL;DR: The domain testing method, which attempts to uncover errors in a path domain by selecting test data on and near the boundary of the path domain, is proposed.
Abstract: White and Cohen have proposed the domain testing method, which attempts to uncover errors in a path domain by selecting test data on and near the boundary of the path domain. The goal of domain testing is to demonstrate that the boundary is correct within an acceptable error bound. Domain testing is intuitively appealing in that it provides a method for satisfying the often suggested guideline that boundary conditions should be tested.
TL;DR: The ability of thirty Type II restriction endonucleases to cleave five different types of highly modified DNA has been examined, and 5-Methylcytosine-rich XP12 DNA and the multiply modified T4 and SP15 DNAs were resistant to most of these endon nucleases.
Abstract: The ability of thirty Type II restriction endonucleases to cleave five different types of highly modified DNA has been examined. The DNA substrates were derived from relatively large bacteriophage genomes which contain all or most of the cytosine or thymine residues substituted at the 5-position. These substituents were a proton (PBS1 DNA), a hydroxymethyl group (SP01 DNA), a methyl group (XP12 DNA), a glucosylated hydroxymethyl group (T4 DNA), or a phosphoglucuronated, glucosylated 4,5-dihydroxypentyl group (SP15 DNA). Although PBS1 DNA and SP01 DNA were digested by most of the enzymes, they were cleaved much more slowly than was normal DNA by many of them. 5-Methylcytosine-rich XP12 DNA and the multiply modified T4 and SP15 DNAs were resistant to most of these endonucleases. The only enzyme that cleaved all five of these DNAs was TaqI, which fragmented them extensively.
TL;DR: Control experiments suggested that such dye transfer is not by an extracellular route, but implied that some CA1 cells are electrotonically coupled, and further electrophysiological and morphological studies are required to resolve the discrepancies among various techniques used to evaluate the amount of coupling in the hippocampus.