julilili42/papers huggingface dataset:
Methyl pyruvate initiates membrane depolarization and insulin release by metabolic factors other than ATP
2001-02-22

The role of mitochondria in stimulus–secretion coupling of pancreatic β-cells was examined using methyl pyruvate (MP). MP stimulated insulin secretion in the absence of glucose, with maximal effect at 5mM. K+ (30mM) alone, or in combination with diazoxide (100μM), failed to enhance MP-induced secretion. Diazoxide (100μM) inhibited MP-induced insulin secretion. MP depolarized the β-cell in a concentration-dependent manner (5–20mM). The sustained depolarization induced by 20mM MP was not influenced by 100μM diazoxide, but the continuous spiking activity was suppressed by 500μM diazoxide. Pyruvate failed to initiate insulin release (5–20mM) or to depolarize the membrane potential. ATP production in isolated β-cell mitochondria was detected as accumulation of ATP in the medium during incubation in the presence of malate or glutamate in combination with pyruvate or MP. There was no difference in ATP production induced by pyruvate/malate or MP/malate in isolated β-cell mitochondria. ATP production by MP/glutamate was higher than that induced by pyruvate/glutamate, but it was much lower than that induced by α-ketoisocaproate/glutamate. Pyruvate (5mM) or MP (5mM) had no effect on the ATP/ADP ratio in whole islets, whereas glucose (20mM) significantly increased the whole islet ATP/ADP ratio. It is concluded that MP-induced β-cell membrane depolarization or insulin release does not relate directly to mitochondrial ATP production. Instead MP may exert a direct extramitochondrial effect, or it may stimulate β-cell mitochondria to produce coupling factors different from ATP to initiate insulin release.
Studies in organic archaeometry II1: analysis of the ancient content of a flask excavated in Troia
2001-02-22

Potsherds of a flask excavated in the ruins of a Late Bronze Age house of Troia VI were analyzed for the ancient content.Traces of lipids were found and analyzed by capillary gas chromatography: lauric acid, myristic acid, palmitic acid, stearic acid and oleic acid were identified -a mixture in which palmitic and stearic acid were the major components.All of these compounds survived predominantly as free fatty acids as well as in form of their salts.Since the form of the flask with a narrow mouth only allowed its use for keeping liquids, it can be assumed that the ancient content was either olive oil or milk; and the presence of lowerchain fatty acids is giving preference to milk.
Molecular analysis of acid ceramidase deficiency in patients with Farber disease
2001-02-23

Farber disease is a rare, autosomal recessively inherited sphingolipid storage disorder due to the deficient activity of lysosomal acid ceramidase, leading to the accumulation of ceramide in cells and tissues. Here we report the identification of six novel mutations in the acid ceramidase gene causing Farber disease: three point mutations resulting in single amino acid substitutions, one intronic splice site mutation resulting in exon skipping, and two point mutations also leading to occasional or complete exon skipping. Of interest, these latter two mutations occurred in adjacent nucleotides and led to abnormal splicing of the same exon. Expression of the mutated acid ceramidase cDNAs in COS-1 cells and subsequent determination of acid ceramidase residual enzyme activity demonstrated that each of these mutations was the direct cause of the acid ceramidase deficiency in the respective patients. In contrast, two known polymorphisms had no effect on acid ceramidase activity. Metabolic labeling studies in fibroblasts of four patients showed that even though acid ceramidase precursor protein was synthesized in these individuals, rapid proteolysis of the mutated, mature acid ceramidase occurred within the lysosome.
Exact relativistic treatment of stationary counterrotating dust disks: Boundary value problems and solutions
2001-02-23

This is the first in a series of papers on the construction of explicit\\nsolutions to the stationary axisymmetric Einstein equations which describe\\ncounter-rotating disks of dust. These disks can serve as models for certain\\ngalaxies and accretion disks in astrophysics. We review the Newtonian theory\\nfor disks using Riemann-Hilbert methods which can be extended to some extent to\\nthe relativistic case where they lead to modular functions on Riemann surfaces.\\nIn the case of compact surfaces these are Korotkin's finite gap solutions which\\nwe will discuss in this paper. On the axis we establish for general genus\\nrelations between the metric functions and hence the multipoles which are\\nenforced by the underlying hyperelliptic Riemann surface. Generalizing these\\nresults to the whole spacetime we are able in principle to study the classes of\\nboundary value problems which can be solved on a given Riemann surface. We\\ninvestigate the cases of genus 1 and 2 of the Riemann surface in detail and\\nconstruct the explicit solution for a family of disks with constant angular\\nvelocity and constant relative energy density which was announced in a previous\\nPhysical Review Letter.\\n
Delone clusters and coverings for icosahedral quasicrystals
2001-02-26

Canonical tilings of type (,Λ), (*,Λ) for quasicrystals are projected from boundaries of Voronoi or Delone cells in an nD lattice Λ. Delone clusters are taken as projections of Delone cells. In general and for icosahedral tilings *, projected from the six-dimensional primitive lattices Λ = P and from D6~2F, the Delone clusters and their filling, covering and fundamental domain properties are analysed by dual tiling and window theory.
Microporous layer for selective detection of VOCs in gases and liquids
2001-02-26

The intention for using microporous polymer is the enhancement of the selectivity and the sensitivity. Microporous polymers show the possibility through the control for analyte ́s mobility into the matrix to extend the sensitivity spectrum for chemo sensors. A sensitive layer with molecular sieving properties is introduced in a sensor array, enhancing the discrimination capabilities of the sensing method tremendously. The volume and the size of the analytes were correlated with the sorption of the analytes in the glassy polymer UE2010. It was found that the size selective sensitive layers of the glassy polymer can discriminate effectively analytes, which are bigger or smaller than the mean pore size. The kinetic diameter ?kin of an adsorbate molecule is the molecular scale to correlate the sorption behaviour of a molecule with the aperture dimension of molecular sieves as zeolites or e.g. microporous polymers. ?kin is widely employed to describe kinetics, permeability and the permselectivity of adsorbate molecules.
Cyclopeptide derivatives for molecular recognition
2001-02-26

Cyclohexapeptides were bound covalently to interference and gold layer and tested for recognition of amino acids in liquid phase. The peptides consist of three L -amino acids as variable building block. Attachment to the surface took place by reaction of the amino group in the side chain of L-cysteine. Reflectometric Interferance Spectroscopy (RIfS) was used for the determination of the interaction of aminoacids. Surface Plasmon Resonance (SPR) was used for validation and additional measurement with small peptides .Cyclopeptides with different side chains demonstrated distinct recognition pattern for different amino acids. The interaction was fast and reversible.
ChemInform Abstract: Total Synthesis of Hapalosin (I) and Two Ring Expanded Analogues (II).
2001-02-27

Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Aged mother cells of Saccharomyces cerevisiae show markers of oxidative stress and apoptosis
2001-03-01

Recently, we and others have shown that genetic and environmental changes that increase the load of yeast cells with reactive oxygen species (ROS) lead to a shortening of the life span of yeast mother cells. Deletions of yeast genes coding for the superoxide dismutases or the catalases, as well as changes in atmospheric oxygen concentration, considerably shortened the life span. The presence of the physiological antioxidant glutathione, on the other hand, increased the life span of yeast cells. Taken together, these results pointed to a role for oxygen in the yeast ageing process. Here, we show by staining with dihydrorhodamine that old yeast mother cells isolated by elutriation, but not young cells, contain ROS that are localized in the mitochondria. A relatively large proportion of the old mother cells shows phenotypic markers of yeast apoptosis, i.e. TUNEL (TdT‐mediated dUTP nick end labelling) and annexin V staining. Although it has been shown previously that apoptosis in yeast can be induced by a cdc48 allele, by expressing pro‐apoptotic human cDNAs or by stressing the cells with hydrogen peroxide, we are now showing a physiological role for apoptosis in unstressed but aged wild‐type yeast mother cells.
Control of Electrical Activity in Central Neurons by Modulating the Gating of Small Conductance Ca2+-activated K+ Channels
2001-03-01

In most central neurons, action potentials are followed by an afterhyperpolarization (AHP) that controls firing pattern and excitability. The medium and slow components of the AHP have been ascribed to the activation of small conductance Ca(2+)-activated potassium (SK) channels. Cloned SK channels are heteromeric complexes of SK alpha-subunits and calmodulin. The channels are activated by Ca(2+) binding to calmodulin that induces conformational changes resulting in channel opening, and channel deactivation is the reverse process brought about by dissociation of Ca(2+) from calmodulin. Here we show that SK channel gating is effectively modulated by 1-ethyl-2-benzimidazolinone (EBIO). Application of EBIO to cloned SK channels shifts the Ca(2+) concentration-response relation into the lower nanomolar range and slows channel deactivation by almost 10-fold. In hippocampal CA1 neurons, EBIO increased both the medium and slow AHP, strongly reducing electrical activity. Moreover, EBIO suppressed the hyperexcitability induced by low Mg(2+) in cultured cortical neurons. These results underscore the importance of SK channels for shaping the electrical response patterns of central neurons and suggest that modulating SK channel gating is a potent mechanism for controlling excitability in the central nervous system.
Plantaricin W from Lactobacillus plantarum belongs to a new family of two-peptide lantibiotics The GenBank accession number for the sequence reported in this paper is AY007251.
2001-03-01

Plantaricin W (Plw) is a new two-peptide bacteriocin, from Lactobacillus plantarum, which inhibits a large number of Gram-positive bacteria. The two peptides, Plwalpha (comprising 29 residues) and Plwbeta (comprising 32 residues), were isolated from the culture supernatants and characterized. The individual peptides had low antimicrobial activity but acted synergistically, and synergism was seen at all mixing ratios tested. The data indicate that the two peptides work in a 1:1 ratio. Chemical analyses showed that both peptides are lantibiotics, but two unmodified cysteines and one serine residue were present in Plwalpha, and Plwbeta contained one cysteine residue. The Plw structural genes were sequenced and shown to encode prepeptides with sequence similarities to two other two-peptide lantibiotics, namely staphylococcin C55 and lacticin 3147. The conserved residues are mainly serines, threonines and cysteines that can be involved in intramolecular thioether bond formation in the C-terminal parts of the molecules. This indicates that these bacteriocins are members of a new family of lantibiotics with common bridging patterns, and that the ring structures play an important functional role. Based on the data a structural model is presented in which each peptide has a central lanthionine and two overlapping thioether bridges close to their C-termini.
Pheromone Cross-Inhibition between Staphylococcus aureus and Staphylococcus epidermidis
2001-03-01

ABSTRACT Cross-inhibition by quorum-sensing pheromones between Staphylococcus aureus and Staphylococcus epidermidis was investigated using all known S. aureus agr pheromone subgroups. All S. aureus subgroups were sensitive towards the S. epidermidis pheromone, with the exception of the recently identified subgroup 4. The subgroup 4 pheromone was also the only S. aureus pheromone able to inhibit the S. epidermidis agr response. The close relation of subgroup 4 to subgroup 1 suggests that subgroup 4 might have evolved from subgroup 1 by mutation under the selective pressure of competition with S. epidermidis . The competition between S. aureus and S. epidermidis by means of quorum-sensing cross talk seems to be generally in favor of S. epidermidis , which might explain the predominance of S. epidermidis on the skin and in infections on indwelling medical devices.
Ethics and Triage
2001-03-01

Abstract A disaster is characterized by an imbalance between needs and supplies. In circumstances in which there occur mass casualties, it is not possible to provide care for all of the victims. Thus, it may be necessary to triage the casualties according to pre-established priorities. The performance of triage is associated with many ethical issues. Currently, no Europe-wide agreement on triage and ethics exists. One system based on a categorization into four groups is proposed. Triage should be avoided whenever possible, but, when it is required, there is an obligation to respect human rights and the humanitarian laws, especially with reference to the Geneva Convention of 1864 and the Universal Declaration of Human Rights of 1948. The condition of informed consent must be followed, even in mass casualty situations. Triage always must follow established medical criteria and cannot be based on any other principles. Triage implies constant re-evaluation of victims as conditions of the victims and of available resources change continuously. In order to facilitate international coordination and cooperation, a universal classification system must be adopted.
All-trans retinoic acid regulates proliferation, migration, differentiation, and extracellular matrix turnover of human arterial smooth muscle cells
2001-03-01

atRA was found to be a potent inhibitor of both haSMC-proliferation and -migration, even in coculture with haEC releasing growth factors. In addition, redifferentiation, ECM synthesis and ECM degradation were regulated by atRA which also influence haSMC migration and intima formation. Thus, atRA-treatment seems to be a promising strategy for the inhibition of processes involved both in atherosclerosis and restenosis.
Enterobactin: the characteristic catecholate siderophore of Enterobacteriaceae is produced byStreptomycesspecies
2001-03-01

Enterobactin is described in the literature as the typical iron-chelating compound (siderophore) produced by bacteria of the family Enterobacteriaceae. In the course of a HPLC with diode array detection screening programme for detection of novel secondary metabolites, enterobactin, its biosynthetic precursor 2,3-dihydroxy-N-benzoylserine and its linear dimer and trimer condensation products were found to be produced by two Streptomyces strains besides the trihydroxamate-type siderophores desferri-ferrioxamine B and E.
Novel methylated triterpenoids of the gammacerane series from the nitrogen‐fixing bacterium Bradyrhizobium japonicum USDA 110
2001-03-01

The nitrogen‐fixing, symbiotic root‐nodule forming bacterium Bradyrhizobium japonicum USDA 110 contained gammacerane derivatives next to triterpenoids of the hopane series. Diploptene, diplopterol, 2β‐methyldiplopterol, aminobacteriohopanetriol and adenosylhopane were accompanied by tetrahymanol and the corresponding novel methylated homologues 2β‐methyltetrahymanol, 20α‐methyltetrahymanol, and 2β,20α‐dimethyltetrahymanol. Incorporation of [ 2 H 3 ]methyl– l ‐methionine indicated that the additional methyl groups originated from methionine, probably with S ‐adenosylmethionine acting as methyl donor, with retention of the three deuterium atoms. The simultaneous presence of hopane and gammacerane derivatives seems a characteristic feature of the genus Bradyrhizobium and the phylogenetically closely related Rhodopseudomonas palustris .
Newly-formed lymph nodes in the submucosa in chronic inflammatory bowel disease.
2001-03-01

Secondary mucosa-associated lymphoid tissue, typically seen as follicular lymphoid hyperplasia, also appears to occur as secondary submucosal lymph nodes. This phenomenon seems inconsistent with the notion that lymph nodes do not develop after birth. We have also noted secondary development of lymph nodes in lymphangioma and lymphangioleiomyomatosis. It is possible that local lymph vessel proliferation, possibly with chronic lymphedema of the tissue involved, is an important prerequisite for lymph node neogenesis.
Size perception in hemianopia and neglect
2001-03-01

Some debate remains as to whether underestimation of the horizontal size of objects in the left part of visual space is a general disturbance in spatial neglect. The issue is unclear because size perception may be influenced by factors other than neglect, e.g. visual field defects such as hemianopia. To disentangle these effects, we compared the performance of patients with pure neglect, pure hemianopia or both on the same size-comparison test. Whereas pure neglect was accompanied by misperception of horizontal object size, patients with pure hemianopia showed an even greater impairment of size perception. Accordingly, the area of maximum lesion overlap of these patients with impaired size perception was not centred around the parietotemporal cortex, which is typically associated with spatial neglect, but rather was found in the occipital lobe (Brodmann areas 17 and 18). The results suggest that spatial neglect is not an inevitable consequence of distorted size perception. The perceptual distortion of objects in the leftward parts of visual space is not sufficient to account for the occurrence of visuospatial neglect.
Epidermal Growth Factor Sensitizes Cells to Ionizing Radiation by Down-regulating Protein Mutated in Ataxia-Telangiectasia
2001-03-01

Epidermal growth factor (EGF) has been reported to either sensitize or protect cells against ionizing radiation. We report here that EGF increases radiosensitivity in both human fibroblasts and lymphoblasts and down-regulates both ATM (mutated in ataxia-telangiectasia (A-T)) and the catalytic subunit of DNA-dependent protein kinase (DNA-PKcs). No further radiosensitization was observed in A-T cells after pretreatment with EGF. The down-regulation of ATM occurs at the transcriptional level. Concomitant with the down-regulation of ATM, the DNA binding activity of the transcription factor Sp1 decreased. A causal relationship was established between these observations by demonstrating that up-regulation of Sp1 DNA binding activity by granulocyte/macrophage colony-stimulating factor rapidly reversed the EGF-induced decrease in ATM protein and restored radiosensitivity to normal levels. Failure to radiosensitize EGF-treated cells to the same extent as observed for A-T cells can be explained by induction of ATM protein and kinase activity with time post-irradiation. Although ionizing radiation damage to DNA rapidly activates ATM kinase and cell cycle checkpoints, we have provided evidence for the first time that alteration in the amount of ATM protein occurs in response to both EGF and radiation exposure. Taken together these data support complex control of ATM function that has important repercussions for targeting ATM to improve radiotherapeutic benefit.
A statistical model for length of psychiatric in‐patient treatment and an analysis of contributing factors
2001-03-01

Objective: Direct illness costs in psychiatry are strongly related to the length of in‐patient stay (LOS). Prior studies have shown that LOS depends upon many factors; however, there is no systematic work on their interrelation and relative contribution. Method: A detailed statistical analysis of the factors explaining LOS for n =4706 consecutive admissions (1994–97) to the psychiatric hospital of the University of Tübingen is presented. Results: The distribution of LOS follows an exponential decay function, suggesting a hazard‐based process. Cox regression indicates that the incidence of discharge and hence LOS is modulated by a number of illness‐related and other factors, and their relationship is explored. Conclusion: While a linear model is commonly assumed, LOS in psychiatry is governed by a hazard‐based process. As a tool in quality management, LOS data for psychiatric hospitals might be routinely analyzed and the effects of non‐illness‐related factors minimized.
The Influence of the Achievement Motive on Spontaneous Thoughts in Pre- and Postdecisional Action Phases
2001-03-01

Drawing on current goal theories of motivation, the authors investigated participants’ spontaneous thoughts in pre- and postdecisional action phases. In contrast with the research originally initiated by Heckhausen and his coworkers, the authors used a repeated-measures design and considered individual differences in achievement motivation. Participants were given a choice between two tasks. They had to report their thoughts twice, before and after they had made the decision. Thought contents were analyzed according to the theory of action phases. The data clearly indicate that spontaneous thoughts reflect different states of mind in pre- and postdecisional action phases. Furthermore, an optimistic bias in thought contents was found, which was, however, moderated by the achievement motive. Success-motivated participants were optimistic after and pessimistic before decision making. The reverse was true for failure-motivated participants. The results were interpreted as an important extension of the achievement-motive nomological network.