Showing papers by "Tulane University published in 1983"
TL;DR: In this paper, the Kohn-Sham density-functional theory was used to estimate the fundamental band gaps of semiconductors and insulators by about 40% due to derivative discontinuities of the exchange-correlation energy.
Abstract: The local-density approximation for the exchange-correlation potential understimates the fundamental band gaps of semiconductors and insulators by about 40%. It is argued here that underestimation of the gap width is also to be expected from the unknown exact potential of Kohn-Sham density-functional theory, because of derivative discontinuities of the exchange-correlation energy. The need for an energy-dependent potential in band theory is emphasized. The center of the gap, however, is predicted exactly by the Kohn-Sham band structure.
1,816 citations
TL;DR: Most of the metastatic neoplasms had significantly lower genomic m5C contents than did most of the benign neoplasm or normal tissues, which might reflect an involvement of extensive demethylation of DNA in tumor progression.
Abstract: The over-all 5-methylcytosine (m5C) content of DNA from normal tissues varies considerably in a tissue-specific manner. By high-performance liquid chromatography, we have examined the m5C contents of enzymatic digests of DNA from 103 human tumors including benign, primary malignant and secondary malignant neoplasms. The diversity and large number of these tumor samples allowed us to compare the range of DNA methylation levels from neoplastic tissues to that of normal tissues from humans. Most of the metastatic neoplasms had significantly lower genomic m5C contents than did most of the benign neoplasms or normal tissues. The percentage of primary malignancies with hypomethylated DNA was intermediate between those of metastases and benign neoplasms. These findings might reflect an involvement of extensive demethylation of DNA in tumor progression. Such demethylation could be a source of the continually generated cellular diversity associated with cancer.
837 citations
TL;DR: In this paper, a linear theory of elastic materials with voids is presented, which differs significantly from classical linear elasticity in that the volume fraction corresponding to the void volume is taken as an independent kinematical variable.
Abstract: A linear theory of elastic materials with voids is presented. This theory differs significantly from classical linear elasticity in that the volume fraction corresponding to the void volume is taken as an independent kinematical variable. Following a discussion of the basic equations, boundary-value problems are formulated, and uniqueness and weak stability are established for the mixed problem. Then, several applications of the theory are considered, including the response to homogeneous deformations, pure bending of a beam, and small-amplitude acoustic waves. In each of these applications, the change in void volume induced by the deformation is determined. In the final section of the paper, the relationship between the theory presented and the effective moduli approach for porous materials is discussed. In the two year period between the submission of this manuscript and the receipt of the page proof, there have been some extensions of the results reported here. In the context of the theory described, the classical pressure vessel problems and the problem of the stress distribution around a circular hole in a field have uniaxial tension have been solved [19,22]. The solution given in the present paper for the pure bending of a beam when the rate effect of the theory is absent is extended to case when the rate effect is present in [21]. The various implications of the rate effect in the void volume deformation are pursued all the subsequent works [19,20,21,22].
804 citations
TL;DR: Intracellular recordings from mammalian neuroendocrine cells showed that steady, injected currents can modify and block periodic spike bursts previously associated with increased neurohormone release, indicating that bursting involves a spike-dependent, positive-feedback mechanism endogenous to single neuro endocrine cells.
Abstract: Intracellular recordings from mammalian neuroendocrine cells showed that steady, injected currents can modify and block periodic spike bursts previously associated with increased neurohormone release. Spike afterpotentials could sum to form plateau potentials, which generated bursts and did not depend on axonal conduction or chemical synapses. Therefore, bursting involves a spike-dependent, positive-feedback mechanism endogenous to single neuroendocrine cells.
203 citations
TL;DR: It is shown that rats, mice and four types of monkey display tissue-specific as well as species-specific differences in the extent of methylation of their cytosine residues, and the highly repeated DNA sequence fraction was more methylated than the moderately repetitive or single copy fractions.
198 citations
TL;DR: In this paper, the authors introduce and calibrates the concept of strategic force in portfolio analysis and PIMS studies to include military concepts of strategic forces, which produces a new paradigm of marketing strategies.
Abstract: Extending portfolio analysis and PIMS studies to include military concepts of strategic force produces a new paradigm of marketing strategies. The author introduces and calibrates the concept of st...
193 citations
TL;DR: This article explored the relationship between domestic labor and wage labor by estimating the relative influence of hours spent in domestic labor (e.g., housework and child care) on women's and men's wages.
Abstract: This paper explores the relationship between domestic labor and wage labor by estimating the relative influence of hours spent in domestic labor (e.g., housework and child care) on women's and men's wages. It is hypothesized that involvement in domestic activities negatively affects wages and is likely to be an important factor in explaining women's lower wages relative to men. Findings from OLS regression analyses of white, currently employed, currently married women and men indicate that domestic labor time significantly decreases both sexes' wages. In order to assess whether this relationship differs by class, the sex-specific earnings equations also are estimated within the working class and the non-working class. The negative effect of domestic labor time on both sexes' income persists in the within-class analyses. Working-class men are more vulnerable to the detrimental influence of domestic production. Unexpectedly, housework and child care time decreases non-workingclass women's wages more so than working-class women's wages. It is noted that these findings should be interpreted with caution due to the cross-sectional nature of the data which precludes an unequivocal assessment of potential nonrecursivity in the linkages among key variables in the model. Overall, the findings imply that a more equitable distribution of work in the home is necessary before labor market inequalities between the sexes can be ameliorated.
176 citations
TL;DR: In spite of alleviation of pain and correction of deformity, normal gait and function are not typically achieved after total knee replacement and an association between degenerative joint disease and decline in proprioception is suggested.
147 citations
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TL;DR: This data indicates that Sweet's syndrome, which is characterized by fever; polymorpbonuclear neutropbilicleukocytosis; elevated FSR; and characteristic, raised, painfulred plaques on the face and limbs, is far more common than this number would indicate.
Abstract: Sweet's syndrome (acute neutrophilic dermatosis) is characterized by fever; polymorphonuclear neutrophilic leukocytosis; elevated ESR; and characteristic, raised, painful red plaques on the face and limbs. Since Sweet first described the syndrome in 1964, more than 150 cases have been reported, but it is assumed that the disorder is far more common than this number would indicate.
144 citations
TL;DR: It is concluded that intraarticular anesthesia has no effect on gait pattern or joint proprioception as measured and injection of local anesthetic into a joint with an intact joint capsule does not compromise joint position sense as measured.
Abstract: Ten healthy young volunteers underwent gait analysis and tests of knee joint position sense. Gait analysis included determination of stride characteristics (veloc ity, cadence, gait cycle, stride length, and single limb support time), force plate analysis, and motion analysis of the knee. The tests of joint position sense examined the ability of the subject to reproduce passive position ing of the knee and the ability to detect change in angle at the knee joint. In a double-blind manner, 10 cc of sterile fluid were injected into the left knee of each volunteer. Five received 2% lidocaine, the other five received sterile saline. All tests were then repeated. No statistically significant difference was observed in any measurement before and after injection in either test group. It is concluded that intraarticular anesthesia has no effect on gait pattern or joint proprioception as measured.Intraarticular local anesthesia is used in sports medi cine to alleviate pain during arthroscopy of the knee under local...
144 citations
TL;DR: The immunocytochemical localization of corticotropin releasing factor (CRF)-containing pathways projecting from the paraventricular nucleus (PVN) to the external layer of the median eminence (ME) in long-term hypophysectomized or adrenalectomized rats is described.
TL;DR: The preliminary data on toxicity and mutagenicity indicate that the evolution of the aflatoxin pathway may be a response to selective pressures from mycophagous species in nature, and this system may be uniquely suited among micrcbial secondary pathways for testing this ecological hypothesis.
Abstract: Publisher Summary Aflatoxins are a family of toxic secondary metabolites produced by certain strains of the common molds Aspergillus flavus and A. parasiticus. The general biosynthetic pathway of aflatoxin appears to be as follows: acetate/malonate norsolorinic acid → averantin → averufin → versiconal hemiacetal acetate → versicolorin A → sterigmatocystin → aflatoxins. Within the context of this general pathway, some mechanistic details concerning formation and subsequent conversion of these individual metabolites have been provided by NMR studies-in particular, 13C-NMR. The chapter focuses on the studies that have provided information concerning bonds broken and formed during the biosynthetic process. The preliminary data on toxicity and mutagenicity indicate that the evolution of the aflatoxin pathway may be a response to selective pressures from mycophagous species in nature. Because of the abundant biosynthetic data and the availability of blocked mutants, this system may be uniquely suited among micrcbial secondary pathways for testing this ecological hypothesis.
TL;DR: It is reported that there were even greater differences in the m5C content of the highly repeated, tandem EcoRI family of DNA sequences from different human organs or cell populations, and these data show that very different degrees of change in methylation levels of various highly repeated DNA sequences accompany differentiation.
Abstract: Previously, we found much tissue- or cell-specificity in the levels of 5-methylcytosine (m5C) in the total human genome as well as in DNA fractions resolved by reassociation kinetics. We now report that there were even greater differences in the m5C content of the highly repeated, tandem EcoRI family of DNA sequences from different human organs or cell populations. The ratio of m5C levels in this DNA fraction from brain, placenta, and sperm was 2.0:1.2:1.0. At a HhaI site in this repeat family, sperm DNA was 5-10 fold less methylated than somatic DNAs. In contrast, the highly repeated Alu family, which is approximately 5% of the genome, had almost the same high m5C content in brain and placenta despite marked tissue-specific differences in m5C levels of the single copy sequences with which these repeats are interspersed. These data show that very different degrees of change in methylation levels of various highly repeated DNA sequences accompany differentiation.
TL;DR: The persistance of SD in a bathing solution that blocked electrically evoked postsynaptic potentials suggests that the contribution of synaptic transmitter release to the propagation of SD should be reappraised.
Abstract: Spreading depression (SD) was studied with intracellular and extracellular recordings and with photometry in slices of rat hippocampus. Repetitive electrical stimulation could initiate SD in either normal medium or in low-Ca2+ medium containing Mn2+, especially during transient hypoxia. The extracellular voltage near CA1 pyramidal somata and dendrites became negative by approximately 18 mV during SD. This negativity peaked more slowly in low-Ca2+ medium containing Mn2+. The wave of negativity propagated across the slice in both media at approximately 6 mm/min. Input resistance of pyramidal neurons became undetectable during SD, and differential voltage recording between neurons and adjacent extracellular space demonstrated that transmembrane potential approached zero. Slices became more opaque during SD. Photometry revealed approximately 10% increase in reflectance and a similar decrease in transmittance of white light, which occurred with a time course similar to the extracellularly recorded voltage shift. These data support the hypothesis that SD represents a large increase in membrane permeability associated with substantial movements of water. The persistance of SD in a bathing solution that blocked electrically evoked postsynaptic potentials suggests that the contribution of synaptic transmitter release to the propagation of SD should be reappraised.
TL;DR: The results suggest that CRF is not merely an ACTH releasing factor, but also a regulatory peptide which may be involved in several stress-related neural responses.
TL;DR: Axons arising from neurons within the interlaminar zones and the S layers of the lateral geniculate nucleus of the squirrel monkey terminate within the supragranular layers of area 17, indicating that both pathways may convey W‐cell information from the retina and the superior colliculus to the striate cortex.
Abstract: Anterograde and retrograde tracing techniques were used to reveal that axons arising from neurons within the interlaminar zones and the S layers of the lateral geniculate nucleus of the squirrel monkey terminate within the supragranular layers of area 17. Specifically, our data indicate that the axons of the neurons housed within the S layers end in a patchlike fashion in cortical layers IIIa and IIIb, while neurons in the interlaminar zones project primarily to layer I. Both pathways may convey W-cell information from the retina and the superior colliculus to the striate cortex.
TL;DR: Results suggest that VIP contained in the chromaffin cells of the frog adrenal gland may exert a local action in stimulating corticosteroid production by the interrenal tissue.
TL;DR: Although women attained higher blood and, presumably, brain levels of ethanol, men did not differ from women in perceived levels of intoxication, physical sensations and mood states, and no difference in the amount of alcohol metabolized, or in the length of time necessary to metabolize thatamount of alcohol, could be found between the sexes.
Abstract: The course of alcohol absorption and elimination was investigated in seven women and nine men administered a moderate (0.66 ml/kg) dose of 95% ethanol. Women were tested during the postmenstrual phase (Day 6–7), when levels of estrogen and progesterone were estimated to be relatively low. Data reflecting alterations in physical sensations, perceived levels of intoxication, and positive and negative mood states were also collected. Women reached significantly higher peak blood alcohol concentrations (BAC's) than men ( p
TL;DR: Aluminium itself affects the permeability of the BBB of rats to small peptide and beta-endorphin, which means that aluminium can affect the blood-brain-barrier in ways that might be involved in dementia.
TL;DR: A brief review of a unique poly- glucose preparation, glucan, which has been developed by the laboratory to enhance host defense mechanisms in a manner bene- ficial to the continued well-being of the host.
TL;DR: Four patients with hypothalamic tumours or idiopathic growth hormone deficiency, who were GH deficient by conventional criteria, responded to 200 micrograms synthetic hpGRF-40 with a clear rise in circulating GH.
TL;DR: The properties of bone tissue as a material and bones as the structural elements of the skeleton are reviewed and summarized and continuum models for this process of bone remodeling due to applied stress are formulated.
Abstract: The properties of bone tissue as a material and bones as the structural elements of the skeleton are reviewed and summarized The first half of this work describes bone tissue microstructure, the stress-strain relations, and the strength and fracture of bone The second and slightly larger half concerns the adaptation of living bone tissue to its load environment Some observations and experiments of bone remodeling due to applied stress are described and continuum models for this process are formulated An example of bone remodeling leading to shape changes in the bone is described as well as an example of bone remodeling leading to changes in the bulk density of the bone tissue
TL;DR: A protocol has been established for the staining of myelin in frozen sections that eliminates the problems routinely encountered with myelin stains such as blotchiness and uneven staining.
TL;DR: Data show that ELH acts directly on the ovotestis and that ELh is the only component of bag cell extract with egg-release activity and had the same dose-response relationship in egg release assays when present in purified form or as a component ofbag cell extract.
TL;DR: It is concluded that decreased position sense may indicate below normal protective reflexes, which may increase the chances of acute or chronic injury.
Abstract: In brief: Twelve members of a professional ballet company were evaluated for laxity of the knee joint. They also underwent a test of knee joint position sense. A group of 12 healthy, active, age-matched controls were similarly tested. All of the dancers met the criteria for loose joints, while only one of the control group had loose joints. In the test of joint position sense the dancers did consistently worse than controls (p <.03) and showed a significant tendency to overestimate the angle to which their knee joint had been passively moved. The authors concluded that decreased position sense may indicate below normal protective reflexes, which may increase the chances of acute or chronic injury.
TL;DR: The purified and characterized the activator protein (GM2 activator) specific for the enzymic hydrolysis of GM2 ganglioside from normal human brain found that the levels of GM 2 activator in both Type B and Type O cases were markedly elevated, and that the two Type AB cases were the results of different causes.
Abstract: In order to understand the etiology of Type AB GM2 gangliosidosis, we have purified and characterized the activator protein (GM2 activator) specific for the enzymic hydrolysis of GM ganglioside from normal human brain. The purified activator from human brain moved as one major protein band in various electrophoretic systems. We have also prepared the antiserum against this activator. The levels and the nature of GM2 activator and beta-hexosaminidase A were examined in the brains of five cases of GM2 gangliosidosis-one Type B, two O, and two Type AB. We found that the levels of GM2 activator in both Type B and Type O cases were markedly elevated, and that the two Type AB cases were the results of different causes. One case had a defective beta-hexosaminidase A and an elevated level of GM2 activator. Although this defective beta-hexosaminidase A could hydrolyze synthetic substrates, it was inactive in the cleavage of natural glycosphingolipids in the presence of the GM2 activator. It could, however, hydrolyze asialo-GM2 and GbOse4Cer in the presence of sodium taurodeoxycholate. The other case had normal beta-hexosaminidase A, but had a very low level of GM2 activator when analyzed by in vitro assay, suggesting the deficiency of this activator. By immunoelectrophoresis, this case was found to be completely devoid of the protein that cross-reacts with the antiserum against the GM2 activator.
TL;DR: Description de la biologie de the reproduction en relation avec les resultats obtenus chez d'autres Angiospermes primitives and de la restriction de l'aire de distribution geographique des populations.
Abstract: Description de la biologie de la reproduction en relation avec les resultats obtenus chez d'autres Angiospermes primitives. Interpretation des mecanismes de declin de ces tara et de la restriction de l'aire de distribution geographique des populations
TL;DR: The data accumulated so far from clinical trials in men with prostate carcinoma suggest that D‐Trp6‐LH‐RH and other LH‐RH agonists can be used for an effective therapy which avoids the side effects of estrogen and the pyschological impact of castration.
Abstract: We have compared the effects of chronic administration of D-Trp6-LH-RH, a superactive agonist of LH-RH, and a potent antagonist, (NAc-p-Cl-D-Phe1,2,D-Trp3,D-Arg6,D-Ala10)LH-RH, on male Copenhagen F-1 rats bearing the Dunning R-3327H prostate adenocarcinoma. Treatment with 25 micrograms of D-Trp6-LH-RH bid for 21 days decreased the weights of the ventral prostate, testes, and adrenals, but had no effect on the weight of the anterior pituitary gland. Administration of similar doses of the antagonist reduced the weight of the ventral prostate, anterior pituitary gland, and adrenals, but did not change the weight of the testes. Both the agonist and antagonist greatly and significantly reduced tumor weight and volume as compared to controls. Serum LH, prolactin, and testosterone levels in Copenhagen F-1 rats bearing Dunning tumors were significantly decreased after treatment with D-Trp6-LH-RH as well as the antagonist. The inhibition of rat prostate tumors achieved with D-Trp6-LH-RH and the antagonistic analog raised the possibility that these compounds could be used clinically in the treatment of prostate carcinoma and other endocrine-dependent neoplasias. The antagonistic analogs have not yet been tried clinically on a chronic basis. However, the data accumulated so far from clinical trials in men with prostate carcinoma suggest that D-Trp6-LH-RH and other LH-RH agonists can be used for an effective therapy which avoids the side effects of estrogen and the pyschological impact of castration.
TL;DR: In this article, a Monte Carlo procedure is devised for simulating a system in which the vibrations are treated as quantum degrees of freedom and all other degree of freedom are treated classically.
Abstract: Solvent effects on vibrational states are treated in the Born–Oppenheimer approximation. A Monte Carlo procedure is devised for simulating a system in which the vibrations are treated as quantum degrees of freedom and all other degrees of freedom are treated classically. The key to this method is the use of a restructured perturbation theory for solving the vibrational Schrodinger equation at each of the solvent configurations sampled. This method also is used to compute Franck–Condon factors. The methods developed are applied to two different problems. First, solvent effects on vibrational transitions in the ground electronic state are considered. It is found that the frequency shift from the gas phase frequency is to the red at low solvent densities, but to blue at high solvent densities. Secondly, the heterogeneous electronic absorption and emission line shapes are simulated in a variety of model solute–solvent systems and the results are discussed in terms of a simple theoretical model.