bluuebunny/crossref_metadata_2025_split huggingface dataset:
Multi‐point Tabu Search for traveling salesman problems
Authors: Niizuma Daichi , Yasuda Keiichiro , Ishigame Atsushi 
Published: May 2006

AbstractThis paper proposes an algorithm—multipoint Tabu Search (MPTS) based on POP—which has several advantages for solving combinatorial optimization problems. The proposed algorithm is applied to some problems of traveling salesmen, which are typical combinatorial optimization problems, in order to verify the performance of the proposed algorithm. The simulation results indicate that the proposed method has higher optimality than the conventional Tabu Search (TS). © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
Life problems and physical illness as risk factors for suicide in older people: a descriptive and case-control study
Authors: HARWOOD DANIEL MICHAEL JAMES , HAWTON KEITH , HOPE TONY , HARRISS LOUISE , JACOBY ROBIN 
Published: May 2006

Background. The role of physical illness and life problems in contributing to suicide in older people is potentially important with regard to suicide prevention.Method. The aim of the study was to determine the life problems other than psychiatric illness contributing to suicide in older people. Semi-structured psychological autopsy interviews, covering life problems and physical illness prior to death, were conducted with informants for 100 people aged 60 years old and over who died through suicide in five English counties. Interviews were completed with informants for 54 age- and sex-matched control subjects who died through natural causes.Results. The three most frequent life problems associated with suicide were physical illness, interpersonal problems, and bereavement. Physical health problems were present in 82% and felt to be contributory to death in 62%. Pain, breathlessness and functional limitation were the most frequent symptoms. Interpersonal problems were present in 55% of the sample and contributory in 31%. The corresponding figures for bereavement-related problems were 47% and 25%. In the case-control analysis, the problems found to be risk factors for suicide were problems related to a bereavement over 1 year before death (OR 3·5, 95% CI 1·2–10·6), and problems with accommodation (OR 5·0, 95% CI 1·1–22·8), finances (p=0·01), and retirement (p=0·02).Conclusion. Physical illness, interpersonal problems and bereavement are commonly associated with suicide in older people, but financial, accommodation, retirement and long- term bereavement-related problems may be more specific risk factors.
GENETIC CONTROL OF IMMUNOLOGICAL RESPONSIVENESS IN GUINEA PIGS TO 2,4-DINITROPHENYL CONJUGATES OF POLY-L-ARGININE, PROTAMINE, AND POLY-L-ORNITHINE
Authors: Green Ira , Paul William E. , Benacerraf Baruj 
Published: May 2006

The ability of guinea pigs to respond immunologically to dinitrophenyl (DNP)-poly-L-arginine, DNP-protamine, DNP polyornithine, and to unsubstituted poly-L-arginine and protamine is linked to the presence of the poly-L-lysine gene. This gene has previously been demonstrated to control the immune response of guinea pigs to poly-L-lysine, to a copolymer of L-glutamic acid and L-lysine and to haptenic derivatives of these materials.
Although the ability to respond to each of these highly charged compounds is linked to the presence of the poly-L-lysine gene, the cellular immune responses to these antigens is highly individually specific.
Glucocorticoid Regulation of ACTH Sensitivity of Adenyl Cyclase in Rat Fat Cell Membranes
Authors: Braun T. , Hechter O. 
Published: May 2006

Plasma membrane sacs of isolated rat fat cells (ghots) possess an adenyl cyclase system, which is activated by lipolytic hormones of disparate molecular structure, including adrenocorticotropin (ACTH), glucagon, and epinephrine. Previous studies indicated that distinctive selectivity units for individual hormones are coupled to the same unit of adenyl cyclase in the fat cell membrane. The present study has shown that ghost cyclase from adrenalectomized and hypophysectomized rats exhibits a striking reduction in response to ACTH, the stimulatory effects of epinephrine, glucagon, or fluoride being unchanged. Pretreatment of adrenalectomized, hypophysectomized, sham operated, or intact rats with the synthetic glucocorticoid, dexamethasone, selectively increased the ACTH response in ghost cyclase preparations. Cortisol, like dexamethasone, increased the ACTH response in ghosts from adrenalectomized rats; 11-deoxycorticosterone was ineffective. The dexamethasone effect to enhance the ACTH response is blocked by actinomycin D or cycloheximide.
The present results show that stimulation of rat fat cell adenyl cyclase by ACTH involves a distinctive molecular entity, which can be clearly differentiated from adenyl cyclase in the membrane as well as from the selectivity sites for epinephrine and glucagon. The data indicate that the biosynthesis of the component required for ACTH stimulation of ghost cyclase—either an ACTH selectivity unit or specific coupling factor—is induced by glucocorticoids at the level of gene regulation.
Neutral Sites for Calcium Ion Binding to Elastin and Collagen: A Charge Neutralization Theory for Calcification and Its Relationship to Atherosclerosis
Authors: Urry D. W. 
Published: May 2006

Neutral, uncharged binding sites for calcium ions are proposed for elastin and collagen. The sites utilize, particularly from a conformational viewpoint, the most striking feature of the amino acid composition, that is, the high glycine content. Glycines favor the formation of β-turns and associated conformations that are known, from studies on ion-transporting antibiotics, to interact with cations. By analogy with certain antibiotics, which are uncharged polypeptides and depsipeptides that bind cations by coordination with neutral acyl oxygens, it is proposed that calcium-ion binding also utilizes uncharged coordinating groups, i.e., neutral sites, in the protein matrix. The protein matrix, which becomes positively charged by virtue of the bound calcium ions, attracts neutralizing phosphate and carbonate ions, which then allow further calcium ion binding. The driving force is, therefore, the affinity of calcium ions for the neutral nucleation sites.
The charge neutralization theory of calcification suggests a fundamental role of organic anions, for example sulfated mucopolysaccharides, in regulating bone formation and in retardation of atherosclerosis. The proposed mechanism contains elements that tend to unify several theories on the pathogenesis of atherosclerosis.
Synthesis of Plastoquinone Analogs and Inhibition of Photosynthetic and Mammalian Enzyme Systems
Authors: Bøler Jan , Pardini Ronald , Mustafa Hanna T. , Folkers Karl , Dilley Richard A. , Crane Frederick L. 
Published: May 2006

New 5-hydroxy- and 5-chloro-6-alkyl-1,4-benzoquinones with one or two methyl groups on the nucleus were synthesized as potential antimetabolites of plastoquinones for biological research on photosynthetic and mammalian enzyme systems; the primary emphasis was on photosynthesis.
2,3-Dimethyl-5-hydroxy-6-phytyl-1,4-benzoquinone completely inhibited in chloroplasts the water-dependent electron transport, but photosystem I was insensitive to this analog. The data are consistent with the interpretation that this analog inhibits electron transport in the chain prior to the site of electron donation from the ascorbate-dichlorophenolindophenol couple. Concentrations of 70 μM and 120 μM of this analog caused about 50 and 100% inhibition, respectively, of cyclic photophosphorylation.
2,3-Dimethyl-5-hydroxy-6-phytyl-1,4-benzoquinone is a new type of inhibitor of photosynthetic electron transport that specifically inhibits the rate-limiting step between photosystems I and II. Structurally related analogs caused inhibitions in the range of 50-100% in chloroplasts.

These analogs showed marginal inhibition in mitochondrial coenzyme Q
10
-oxidase systems from beef heart.
Calf Crystallin Synthesis in Frog Cells: The Translation of Lens-Cell 14S RNA in Oocytes
Authors: Berns A. J. M. , Kraaikamp M. Van , Bloemendal H. , Lane C. D. 
Published: May 2006

14S RNA isolated from calf-lens polyribosomes was injected into oocytes of the frog
Xenopus laevis
. Oocytes injected with 14S RNA and buffer contained a protein resembling the A2 chain of calf α-crystallin; oocytes injected with buffer alone contained no crystallin-like material. αA2 crystallin polypeptides were identified by various criteria: urea-gel electrophoresis under acidic and basic conditions, gel electrophoresis in sodium dodecyl sulfate, N-terminal analysis, and paper chromatography of methionine-containing tryptic peptides.

It is concluded that when it is injected into a living frog oocyte, the 14S RNA from lens tissue is reasonably stable and has the properties of an αA2 crystallin messenger. The messenger requires no lens cell-specific components for translation within the oocyte, and the translational machinery of the frog cell will accept messenger RNA from a totally different cell type from another species.
The A2 chains of α-crystallin extracted from lens tissue possess an acetylated N-terminal methionine residue; the N-terminal methionine of αA2 chains derived from frog oocytes injected with 14S RNA was also acetylated.
Thymosin Corrects the Abnormal DNA Synthetic Response of NZB Mouse Thymocytes
Authors: Dauphinee Michael J. , Talal Norman , Goldstein Allan L. , White Abraham 
Published: May 2006

New Zealand Black (NZB) mice develop after 16 weeks of age an autoimmune and lymphoproliferative disease which is a model for systemic lupus erythematosus and lymphoid malignancy in humans. At this age, the mice manifest a progressive decline in T lymphocyte (thymus-derived lymphocyte) functions and serum thymosin levels. Thymocytes from 8-week old NZB mice exhibit an abnormal DNA synthetic response when transplanted into lethally irradiated C57B1/6 recipients. DNA synthesis (measured as the incorporation of radioactively labeled 5-iodo-2′-deoxyuridine) is delayed in onset and still increasing 6 days after cell transfer. By contrast, 2-week old NZB thymocytes show a normal response which is rapid in onset and completed by day 6.
NZB mice were injected with thymosin fraction 5 or with bovine serum albumin starting at 2 weeks of age. Thymocytes from 8-week old thymosin-treated mice showed a normal DNA synthetic response, whereas the albumin-treated controls showed the abnormal response expected at this age. The ability of thymosin to correct the DNA synthetic response was related to dose and duration of treatment. These results suggest that thymosin can induce a more normal state of thymocyte differentiation in NZB mice. If abnormal thymocyte differentiation is related to the subsequent emergence of autoimmunity and lymphoid malignancy, then continuous treatment with thymosin may have therapeutic potential. These experiments suggest that an endocrine disturbance may contribute to autoimmune and lymphoproliferative disease in NZB mice and possibly in humans.
Nonasymptotic Species Richness Models and the Insects of British Trees
Authors: Strong Donald R. 
Published: May 2006

Nonasymptotic models of species diversity are those that do not consider negative feedback between number of species in a biota and the net rate of species addition. These models propose species richness differences to be primarily the product of geologic age differences among biotas. Nonasymptotic explanations are traditional for various diversity difference spectra, including latitudinal diversity gradients and the greater species richness of ancient compared to young lakes. I review new evidence that renders these nonasymptotic explanations doubtful.
The only uncontested evidence in favor of nonasymptotic species accumulation is Southwood's correlation between the number of insect species associated with British tree taxa and the number of Quaternary fossil records of these taxa. I show that nonasymptotic explanations of species richness variation are unacceptable for this system also. The variation in insect species richness among these taxa is well accounted for by a species-area relationship. The species richness asymptote is attained within a few hundred years, and the influence of cumulative host taxon abundance (number of fossil records) upon insect species richness is insignificant after the statistical influence of present-day host plant range is removed. I conclude Southwood's correlation to lack causality; it probably derives from a correlation between the number of fossil records of the host taxa and their present range.
Association of the Membrane-Penetrating Polypeptide Segment of the Human Erythrocyte MN-Glycoprotein with Phospholipid Bilayers. I. Formation of Freeze-Etch Intramembranous Particles
Authors: Segrest Jere P. , Gulik-Krzywicki T. , Sardet Christian 
Published: May 2006

The membrane-penetrating segment of the surface MN-glycoprotein of the human erythrocyte is contained intact within the tryptic peptide T(is). We report here on the association of this peptide with hydrated phospholipid vesicles. Under these conditions 80 Å intramembranous particles, as seen by freeze-etch electron microscopy, are produced that are similar in size to those seen in the native erythrocyte membrane. These particles increase in number as a linear function of T(is) concentration and a plot of particle number versus concentration is compatible with a micelle-like phenomenon; from this curve the critical concentration for the formation of particles is estimated to be approximately one mole of T(is) to 120 moles of lecithin. These data suggest that the membrane-penetrating peptide T(is) is being incorporated, monomerically and multimerically, within the hydrocarbon phase of lecithin bilayers.
From these data it can be calculated that each intramembranous particle contains between 10 and 20 T(is) monomers. The peptide portion of each particle, therefore, has a molecular weight of 45,000-85,000.

An exact analogy cannot be drawn at this time between the
in vivo
structure of erythrocyte intramembranous particles and the reconstituted particles described here, although an argument has been constructed to support this possibility. What is clear is that the reconstituted system promises to be useful for further examination of protein-lipid interactions in membranes.
HeLa cell poly(A)- mRNA codes for a subset of poly(A)+ mRNA-directed proteins with an actin as a major product
Authors: Kaufmann Yael , Milcarek Christine , Berissi Hanna , Penman Sheldon 
Published: May 2006

Poly(A)+ and poly(A)- mRNA from HeLa cells were separated and translated in heterologous messenger-dependent protein synthesizing systems. Two-dimensional electrophoretic analysis revealed three classes of polypeptides. At the level of detectability in the electropherograms, a small number (about 10) of proteins were detected only among the poly(A)- mRNA products, a larger number (about 40) were produced by both poly(A)- and poly(A)+ mRNA, and a large number of polypeptides were found exclusively in the poly(A)+ mRNA products. The major product of both poly(A)+ and poly(A)- mRNA was shown to be the β form of actin.
Previous cross hybridization measurements suggested little homology between poly(A)+ and poly(A)- mRNA populations. In view of the apparent identity of many poly(A)- products with those of poly(A)+, the homology between poly(A)+ and poly(A)- mRNA sequences was examined in greater detail. cDNA complementary to only the most abundant poly(A)+ message sequences was prepared. About 10% of this cDNA hybridized to abundant sequences in the poly(A)- fraction. This corresponded to only 2% of the total mass of poly(A)+ mRNA and accounted for the failure to detect cross hybridization in previous experiments. Thus, a small number of poly(A)+ sequences appear to be present in relatively high concentration in poly(A)- mRNA as evidenced by both the translation products and the cross hybridization results.
Isolation of a protein scaffold from mitotic HeLa cell chromosomes
Authors: Adolph K. W. , Cheng S. M. , Paulson J. R. , Laemmli U. K. 
Published: May 2006

We have recently shown that, after the histones and most of the nonhistone proteins are gently removed from HeLa metaphase chromosomes, the chromosomal DNA is still highly organized and relatively compact. The structure of these histone-depleted chromosomes is due to the presence of a number of nonhistone proteins that form a central scaffold that retains the approximate size and shape of intact chromosomes and to which the DNA is attached, predominantly forming loops. We now demonstrate that the protein scaffold may be isolated independently of the DNA by treating HeLa chromosomes with micrococcal nuclease before removing the histones.
The chromosomal scaffolds may be isolated by sucrose density gradient centrifugation as a well-defined peak that is stable in 2 M sodium chloride, but is dissociated by treatment with proteases, 4 M urea, or 0.1% sodium dodecyl sulfate. Polyacrylamide gel electrophoresis reveals that the protein content of scaffold preparations is identical to that of histone-depleted chromosomes. Fluorescence microscopy of purified scaffolds in isolation buffer shows that the particles still possess the familiar chromosome morphology. When the scaffolds are examined in the electron microscope, a fibrous structure with the approximate size and shape of intact, paired chromatids is seen. Less than 0.1% of the chromosomal DNA and virtually no histones are associated with the purified scaffold structures.
TWELVE CASES OF ACUTE ESOPHAGEAL MUCOSAL LESION
Authors: Tsumura Takehiko , Maruo Takanori , Tsuji Kentaro , Osaki Yukio , Tomono Naomi 
Published: May 2006

Background and Aims:  The incidence of erosive esophagitis in emergent endoscopy for upper gastrointestinal bleeding is not rare but the clinical and endoscopic findings have not been fully investigated. The aim of the present study was to clarify features of acute esophagitis cases showing acute onset and severe endoscopic findings.Methods:  We defined severe esophagitis that endoscopically showed circumferential diffuse mucosal lesion involving at least the entire lower third of the esophagus as acute esophageal mucosal lesion and investigated the clinical and endoscopic characteristics.Results:  We experienced six cases of black or dark esophagitis and six cases of non‐black esophagitis. Both groups showed common clinical features. Patients were predominantly males older than middle age. The presenting symptoms were upper gastrointestinal bleeding such as coffee‐ground‐like vomit, hematemesis or tarry stool. Seven cases had a history of taking non‐steroidal anti‐inflammatory drugs. Endoscopically, both types of case showed diffuse circumferential erosion in the lower esophagus, which continuously extended, and worsened towards the esophagogastric junction. All had esophageal sliding hernia and five cases had duodenal mucosal lesion. All cases rapidly improved with a proton pump inhibitor except one case.Conclusion:  Black and non‐black esophagitis was considered to belong to the same disease entity, acute esophageal mucosal lesion, which should be recognized as a differential diagnosis on emergency endoscopy for upper gastrointestinal bleeding.
NF‐κB Activation Pathway is Essential for the Chemokine Expression in Intestinal Epithelial Cells Stimulated with Clostridium difficile Toxin A
Authors: Kim J. M. , Lee J. Y. , Yoon Y. M. , Oh Y.‐K. , Youn J. , Kim Y.‐J. 
Published: May 2006

AbstractIntestinal epithelial cells are known to upregulate the expression of several chemokines in response to stimulation with bacterial toxin. However, the cellular mechanisms of Clostridium difficile toxin A‐induced mucosal inflammation have not yet been fully elucidated. In this study, we investigated whether nuclear factor‐kappa B (NF‐κB) could regulate chemokine expression in intestinal epithelial cells. Toxin A increased the levels of NF‐κB complexes containing p65/p50 heterodimers and p65/p65 homodimers. Concurrently, toxin A decreased the levels of IκBα. Toxin A stimulation also increased the signals of phosphorylated IκB kinase (IKK)α/β and NF‐κB‐inducing kinase (NIK). In the toxin A‐stimulated HT‐29 cells, the suppression of IKK or NIK inhibited the upregulation of downstream target genes of NF‐κB such as IL‐8 and monocyte‐chemotactic protein (MCP)‐1 and similarly, inhibition of NF‐κB also downregulated the expression of IL‐8, growth‐related oncogene‐α, and MCP‐1. These results suggest that NF‐κB signalling events may be involved in the inflammatory responses to toxin A produced by toxigenic C. difficile.
Effects of melatonin on the oxidant/antioxidant status and lung histopathology in rabbits exposed to cigarette smoke
Authors: UNLU Mehmet , FIDAN Fatma , SEZER Murat , TETIK Levent , SAHIN Onder , ESME Hidir , KOKEN Tulay , SERTESER Mustafa 
Published: May 2006

Objectives and background:  To evaluate the effects of cigarette smoking on the histopathology and the oxidant/antioxidant status of the lungs and to test the potential antioxidant benefits of melatonin on these induced changes.Methodology:  Rabbits were exposed to cigarette smoke in a glass chamber for 1 h daily for 1 month with or without intraperitoneal melatonin injection. A melatonin control group was given intraperitoneal melatonin only. A control group was exposed to clean air only. At the end of 1 month, animals were sacrificed and lung tissues were examined histopathologically. Blood levels of protein sulphydryls, carbonyls, prostaglandin F2α (PGF2α), malondialdehyde (MDA), glutathione peroxidase and superoxide dismutase (SOD) were measured.Results:  Intraparenchymal vascular congestion and thrombosis, intraparenchymal haemorrhage, respiratory epithelial proliferation, number of macrophages in the alveolar and bronchial lumen, alveolar destruction, emphysematous changes and bronchoalveolar haemorrhage scores were significantly increased in rabbits exposed to cigarette smoke compared with the control group. Protein sulphydryls and SOD levels were significantly decreased; carbonyls, PGF2α and MDA levels were significantly increased in the smoke exposed rabbits. Administration of melatonin to rabbits exposed to cigarette smoke caused a reduction in the bronchoalveolar haemorrhage score and blood carbonyls levels. Other parameters were unaffected by melatonin.Conclusion:  Exposure to cigarette smoke causes severe histopathological changes and negatively affects the oxidant/antioxidant status in the lungs of rabbits. A low daily dose of melatonin has some protective effects on histopathological changes and oxidant/antioxidant status of the lungs in smoke exposed rabbits.