bluuebunny/crossref_metadata_2025 huggingface dataset:
Arsenite inhibits p53 phosphorylation, DNA binding activity, and p53 target gene p21 expression in mouse epidermal JB6 cells,
Authors: Tang Faqing , Liu Guangming , He Zhiwei , Ma Wei‐Ya , Bode Ann M. , Dong Zigang
Published: May 2006

Epidemiologic investigations demonstrated that arsenite exposure increases the risk of various human cancers, including skin, lung, bladder, and kidney cancers. However, oral administration of arsenite alone has failed to induce tumors in animal models, suggesting that arsenic may act to enhance mutagenicity induced by other carcinogens. Arsenite may function as a co‐carcinogen, acting by inhibiting repair of carcinogen‐induced DNA damage mediated by p53 and p21, a p53 target gene. To elucidate the interaction between arsenite and p53 tumor suppressor protein, we studied the effect of arsenite on ultraviolet B (UVB)‐induced p53 phosphorylation, p53 DNA binding activity, and p53‐induced target gene transactivation in the JB6 Cl41 mouse epidermal skin cell model. Our results indicated that arsenite suppressed UVB‐induced p53 phosphorylation and p53 DNA binding activity. Arsenite also inhibited casein kinase 2 (CK2) activity and decreased p53‐regulated p21 protein expression. These data suggest that the direct inhibition of p53 functional activation is one of the mechanisms through which arsenite interferes with p53 function, and thus may be a significant mechanism for the co‐carcinogenic effects of arsenite. © 2006 Wiley‐Liss, Inc.
Stathmin overexpression cooperates with p53 mutation and osteopontin overexpression, and is associated with tumour progression, early recurrence, and poor prognosis in hepatocellular carcinoma
Authors: Yuan R‐H , Jeng Y‐M , Chen H‐L , Lai P‐L , Pan H‐W , Hsieh F‐J , Lin C‐Y , Lee P‐H , Hsu H‐C
Published: May 2006

Stathmin, a major microtubule‐depolymerizing protein, is involved in cell cycle progression and cell motility. This study aimed to elucidate its role in the progression, early tumour recurrence (ETR), and prognosis of hepatocellular carcinoma (HCC). Stathmin mRNA was overexpressed in 88/156 (56%) resected, unifocal, primary HCCs, while p53 mutation was present in 72 (46%) and osteopontin mRNA overexpression in 79 (51%). Stathmin mRNA expression exhibited high concordance (93%) with protein expression in 107 cases examined by immunohistochemistry. Stathmin overexpression correlated with high α‐fetoprotein (>200 ng/ml, p = 0.02), larger tumour size (>5 cm, p = 0.012), high tumour grade (p < 0.0002), high tumour stage (stage IIIA–IV) with vascular invasion and various degrees of intrahepatic metastasis (p < 1 × 10−8), ETR (p = 0.003), and lower 5‐year survival (p = 0.0007). Stathmin protein expression was often more intense in the peripheral regions of tumour trabeculae, tumour borders, and portal vein tumour thrombi. Stathmin overexpression correlated with p53 mutation (p = 0.017) and osteopontin overexpression (p = 1 × 10−8), both of which were associated with vascular invasion (both p < 0.0001) and poorer prognosis (p < 0.0004 and p = 0.0004, respectively). Regardless of the status of p53 mutation or osteopontin expression, stathmin overexpression was associated with higher vascular invasion (all p < 0.0001). Approximately 90% of HCCs harbouring stathmin overexpression with concomitant p53 mutation or osteopontin overexpression exhibited vascular invasion, and hence the lowest 5‐year survival, p = 0.00018 and p = 0.0009, respectively. However, we did not find that stathmin overexpression exerted prognostic impact independent of tumour stage. In conclusion, stathmin expression correlates with metastatic potential, is an important prognostic factor for HCC, and may serve as a useful marker to predict ETR. Copyright © 2006 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
GLP‐compliant assay validation studies: considerations for implementation of regulations and audit of studies
Authors: Li Henry , Sharp Garreth , Pilkington Connie , Pifat Dominique , Petteway Steve
Published: May 2006

Bioanalytical methods used in nonclinical safety studies are validated to demonstrate that the methods are reliable and reproducible for the intended use. Analytical method validation studies should be designed according to regulatory guidance on method validation. A cell‐based assay is described to discuss fundamental validation parameters, such as repeatability, immediate precision, accuracy, and linearity. A Good Laboratory Practice (GLP) compliance program provides a useful platform for ensuring data integrity in assay validation studies. A good understanding of the method validation concepts and regulatory requirements will help Quality Assurance Unit (QAU) auditors focus on key areas and be more effective when auditing assay validation protocols, final reports, and associated data. Copyright © 2006 John Wiley & Sons, Ltd.
International Marketing Applications according to the ICH CTD format: comparison of structure and document requirements
Authors: Gelman Rita Segal
Published: May 2006

With the development of the Common Technical Document (CTD) by the International Conference on Harmonisation (ICH), United States, European Union and Japan now have a common format for the organization of documents in regulatory applications. This paper presents a top‐level assessment of how the required technical contents of the Biologic License Application (BLA), the Marketing Authorization Application (MAA) and Japan's New Drug Application should be structured according to the ICH CTD format. The article may be of assistance for Quality Assurance auditor when auditing MAAs. Copyright © 2006 John Wiley & Sons, Ltd.
Receptor recycling mediates plasma membrane recovery of dopamine D1 receptors in dendrites and axons after agonist‐induced endocytosis in primary cultures of striatal neurons
Authors: Martin‐Negrier Marie‐Laure , Charron Giselle , Bloch Bertrand
Published: May 2006

The pharmacological stimulation of G‐protein‐coupled receptor induces receptor internalization. Receptor's fate after the step of internalization remains poorly characterized despite its incidence on the neuronal responsiveness. In this context, we studied the dopamine (DA) D1 receptor (D1R) trafficking in a model of striatal neuronal culture that endogenously express the D1R. We first characterized by immunohistochemistry the spatial distribution of the compartments involved in the endocytic pathways and then the D1R trafficking in dendrites and axons. In dendrites, immunohistochemical analysis showed that acute stimulation by the D1R agonist SKF 82958 (1 μM) induces an internalization of D1R in early endosomes labeled with Alexa‐488‐conjugated transferrin. We show that, 20 min after removal of the agonist, the D1R immunolabeling pattern returns to the basal state in dendrites and in axons. Recovery was unaffected by cycloheximide (70 μM) but was prevented by monensin (100 μM) that inhibits endosomal acidification and receptor recycling. These data suggest that dendritic and axonal D1Rs are internalized after agonist stimulation and targeted to the recycling pathway demonstrating that the machinery involved in GPCR endocytosis and recycling is functional both in dendrites and in axons. Temporal characteristics observed for the recovery of D1R density to the basal state and those observed for the resensitization process strongly suggest that D1R recycling supports the receptor resensitization. Synapse 60:194–204, 2006. © 2006 Wiley‐Liss, Inc.
The preparation of ZnGa2O4 doped with Mn‐Mg and Tm for green and blue phosphors
Authors: Singh Binod Kumar , Ryu Hojin , Kim Chang‐Hae , Jung Ha‐Kyun , Park Jung‐Kyu , Jung Kyeung‐Yeol , Chang Ho‐Jung
Published: May 2006

Phosphor powders of zinc gallate (ZnGa2O4) with Mg and Mn for green and Tm‐Mg for blue luminescence were prepared by solid state reaction method for their improved luminescent properties. Green‐luminescence emitting ZnMnGa2O4 reached maximum intensity at Mn = 0.005 mol% and further improvement was achieved by the addition of Mg2+. Tm‐Mg based zinc gallate phosphor exhibited a strong blue emission, centered at ∼420 nm with the maximum intensity achieved for 0.003 mol% of Mg and 0.015 mol% of Tm. This study established the possibilities of controlling the luminescent characteristics of zinc gallate by adding various elements. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
High performance control implementation of stand alone induction generator using active power filter
Authors: Nishida Katsumi , Ahmed Tarek , Nakaoka Mutsuo
Published: May 2006

This paper presents a novel dynamic model in the stationary reference frame for a diode bridge rectifier with a DC‐link filter directly connected to a three‐phase induction generator (IG). Moreover, a hybrid excitation system, consisting of a capacitor bank and a small‐scale active power filter (APF), regulates the stand‐alone IG system's output voltages by controlling its reactive‐current component, and cancels harmonic currents generated by a nonlinear diode rectifier load. A deadbeat current control strategy for the small‐scale APF is used to enhance the operating performances of the stand‐alone IG. This power generating system can be used for small hydro and wind rural applications where the generated electrical power is supplied to DC and AC loads. The measurement results validate the proposed power generating system, with the deadbeat current controller as a good application for the IG to reduce the total system cost and the required number of sensors. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.
An extra dimension in nucleic acid sequence recognition
Authors: Fox Keith R , Brown Tom
Published: May 2006

Introduction 312

Triple helices in DNA 312

Chemically modified TFOs 313

Further development 316

Recognition of GC base pairs 316

Recognition of TA base pairs 316

Recognition of AT base pairs 317

Recognition of CG base pairs 317

RNA triplexes 317

Kinetics of triplex formation 318

Practical applications of triplexes 318

Conclusions 319

References 319

Watson–Crick base pairing is a natural molecular recognition process that has been exploited in molecular biology and universally adopted in many fields. An additional mode of nucleic acid sequence recognition that could be used in combination with normal base pairing would add an exta dimension to nucleic acid interactions and open up many new applications. In principle the triplex approach could provide this if developed to recognize any DNA sequence. To this end modified nucleosides have been incorporated into triple-helix-forming oligonucleotides (TFOs) and used to recognize mixed sequence DNA with high selectivity and affinity at neutral pH. Continuing developments are directed towards improving TFO affinity at high pH and increasing triplex association kinetics. A number of applications of triplexes are currently being explored.
Lebensqualität und Wohlbefinden im Alter
Authors: Gunzelmann Thomas , Schmidt Silke , Albani Cornelia , Brähler Elmar
Published: May 2006

Zusammenfassung: Lebensqualität und Wohlbefinden haben hohe klinische Relevanz in der Bewertung therapeutischer Maßnahmen bei älteren Menschen, so dass geeignete diagnostische Verfahren notwendig sind. In der vorliegenden Arbeit wird die psychometrische Qualität des EUROHIS-QOL und des WHO-5 in einer Stichprobe von N = 744 60-Jährigen und Älteren (51 % weiblich) geprüft. Beide Verfahren weisen eine hohe Reliabilität (Cronbach's α) von .86 bzw. .92 auf. Während die eindimensionale faktorielle Struktur des WHO-5 bestätigt werden konnte, wurde für den EUROHIS-QOL eine zweidimensionale Struktur ermittelt (personale und externale Faktoren der Lebensqualität). Als Referenzdaten für Ältere werden Häufigkeiten der Antwortkategorien, Mittelwerte und Prozentrangwerte dargestellt. Es wurden keine bedeutsamen Alters- oder Geschlechtseffekte gefunden.
Reevaluation of surface rupture parameters and faulting segmentation of the 2001 Kunlunshan earthquake (Mw7.8), northern Tibetan Plateau, China
Authors: Xu Xiwei , Yu Guihua , Klinger Y. , Tapponnier Paul , Van Der Woerd Jerome
Published: May 2006

The 14 November 2001,Mw= 7.8 Kunlunshan earthquake ruptured the westernmost part of the Kunlun Fault, northern Tibetan Plateau. The main segment affected by this event was the Kusaihu segment. Field investigations allowed us to constrain the length, the width, and the coseismic horizontal displacement distribution of the Kunlunshan earthquake rupture zone. The mapped surface rupture zone starts from 90.257°E in the west and ends at 94.795°E in the east with a total length of 426 km. It consists of three main sections, the western strike‐slip section, the transtensional section, and the eastern strike‐slip section. The rupture zone is oriented N100° ± 10°E on average. The distribution of the coseismic horizontal displacements is characterized by multiple peaks departing clearly from a general bell‐shaped distribution. Reassessment of the maximum coseismic horizontal left‐lateral displacement yields a value of 7.6 ± 0.4 m at the site (35.767°N, 93.323°E) consistent with independent measurements derived from interferometric synthetic aperture radar and seismology. From this site the horizontal displacement decreases unevenly to both the west and east. Coseismic vertical (reverse) displacement is also noted at the eastern end of the rupture but it remains much smaller than the horizontal component. The width of the rupture zone varies from site to site from several meters to few kilometers. The maximum width measured reaches 8 km along the Yuxi Feng subsection where a large number of shaking related cracks were well developed.
Modeling the lithospheric magnetic field over France by means of revised spherical cap harmonic analysis (R‐SCHA)
Authors: Thébault E. , Mandea M. , Schott J. J.
Published: May 2006

We have recently proposed the revised spherical cap harmonic analysis (R‐SCHA) modeling technique. The new mathematical functions represent faithfully the spatial variations of potential fields in a restricted area. In this paper, we tackle the inverse problem and outline the efficiency of the new basis functions with respect to real magnetic data. Processing simultaneously repeat stations, observatory, aeromagnetic, and CHAMP satellite data provides our first vector lithospheric field model over France, which extends from surface to 500 km of altitude. The magnetic field is represented with a minimum horizontal spatial representation of 40 km at the mean Earth radius. The magnetic lithospheric map consistency is confirmed with a comparison to known geological features. The model variation with altitude also suggests that the major French magnetic anomaly, the Paris basin anomaly, is produced by a deep‐rooted geological structure. These results demonstrate the superiority of regional modeling over global modeling for delineating small‐scale details in the lithospheric field. In view of forthcoming satellite missions, like Swarm, the revised spherical cap harmonic analysis method will help to accurately represent the lithospheric field for more detailed geological interpretations.
Modified Labeling Technique for in vivo Visualization of Platelets in the Cerebral Microcirculation of Mongolian Gerbils
Authors: Waldner Maximilian , Hutter Joerg , Uhl Eberhard , Baethmann Alexander , Lehmberg Jens
Published: May 2006

Activation of platelets induces interactions with platelets, endothelial cells, and leukocytes. In vivo observation of these interactions in the cerebral microcirculation is rare. The purpose of the present study was to develop a model enabling the in vivo observation of platelet kinetics in the cerebral microcirculation. Intravital fluorescence microscopy was performed in the Mongolian gerbil. Platelets of a donor were labeled ex vivo with carboxyfluorescein diacetat-succinimidylester (CFDA-SE), providing long-term fluorescence. Platelet function was tested ex vivo by flow cytometric analysis and in vivo by analyzing platelet-endothelium interactions. Labeled platelets stimulated with adenosine diphosphate ADP (200 μmol/L) or thrombin (1000 U/L) showed aggregation in flow cytrometric analysis, whereas unstimulated platelets were not aggregated. Irradiation of the brain surface after intravenous injection of the photosensitizing dye Photosan first induced rolling and firm adherence of platelets on arteriolar and venular endothelium, followed by the formation of a thrombus obstructing the vessel. Quantitative analysis (nx100 μm−1 min−1) before and after 6 mins of irradiation showed 2.6±3.2 versus 29.0±28.9 rolling, and 0.0±0.0 versus 1.7±2.3 firm adherent platelets in arterioles, and 3.9±3.3 versus 36.6±20.9 rolling and 0.0±0.0 versus 13.6±8.9 firm adherent platelets in venules. Thus, we conclude that ex vivo labeling of platelets with CFDA-SE does not activate platelets. Platelet aggregation and adhesion was achieved by platelet-specific stimulation such as ADP, thrombin or irradiation. In vivo assessment of physiologic and pathophysiologic mechanisms of platelets in the cerebral microcirculation can be achieved in this model.
Pharmacological FMRI: Measuring Opioid Effects on the BOLD Response to Hypercapnia
Authors: Pattinson Kyle TS , Rogers Richard , Mayhew Stephen D , Tracey Irene , Wise Richard G
Published: May 2006

Opioid binding to the cerebral blood vessels may affect vascular responsiveness and hence confound interpretation of blood oxygen level-dependent (BOLD) responses, which are usually interpreted as neuronal in origin. Opioid binding varies in different brain regions. It is unclear whether opioids alter neurovascular coupling, or whether their effects are purely neuronal. This study used BOLD functional magnetic resonance imaging (FMRI) to investigate the effect of a μ-opioid agonist remifentanil, on cerebrovascular CO2 reactivity (being one component of neurovascular coupling). Hypercapnic challenges were delivered to human volunteers, while controlling potential opioid-induced respiratory depression. The BOLD signal increase to hypercapnia was compared before and during remifentanil administration. Remifentanil was shown not to have a generalised effect on CO2 responsiveness in the cerebral vasculature. However, it caused a significant reduction in the positive BOLD response to hypercapnia in the bilateral primary sensorimotor cortices, bilateral extrastriate visual areas, left insula, left caudate nucleus, and left inferior temporal gyrus. We conclude that remifentanil does not modulate cerebrovascular CO2 reactivity, as we saw no difference in BOLD response to hypercapnia in areas with high opioid receptor densities. We did however see a focal reduction in areas related to motor control and putative task activation, which we conclude to be related to changes in neuronal activity related to the sedative effects of remifentanil. Our method of controlling CO2 levels effectively mitigated the potential confound of respiratory depression and allowed comparison over a similar range of CO2 levels. We suggest that similar methodology should be used when investigating other potentially vasoactive compounds with FMRI.
Transport processes in magnetically confined plasmas in the nonlinear regime
Authors: Sonnino Giorgio
Published: May 2006

A field theory approach to transport phenomena in magnetically confined plasmas is presented. The thermodynamic field theory (TFT), previously developed for treating the generic thermodynamic system out of equilibrium, is applied to plasmas physics. Transport phenomena are treated here as the effect of the field linking the thermodynamic forces with their conjugate flows combined with statistical mechanics. In particular, the Classical and the Pfirsch-Schlüter regimes are analyzed by solving the thermodynamic field equations of the TFT in the weak-field approximation. We found that, the TFT does not correct the expressions of the ionic heat fluxes evaluated by the neoclassical theory in these two regimes. On the other hand, the fluxes of matter and electronic energy (heat flow) is further enhanced in the nonlinear Classical and Pfirsch-Schlüter regimes. These results seem to be in line with the experimental observations. The complete set of the electronic and ionic transport equations in the nonlinear Banana regime, is also reported. A paper showing the comparison between our theoretic results and the experimental observations in the JET machine is currently in preparation.
Self-aligned surface treatment for thin-film organic transistors
Authors: Myny Kris , De Vusser Stijn , Steudel Soeren , Janssen Dimitri , Müller Robert , De Jonge Stijn , Verlaak Stijn , Genoe Jan , Heremans Paul
Published: May 2006

For organic thin-film transistors where source-drain contacts are defined on the gate dielectric prior to the deposition of the semiconductor (“bottom-contact” configuration), the gate dielectric is often treated with a self-assembled molecular monolayer prior to deposition of the organic semiconductor. In this letter, we describe a method to apply an ultrathin solution-processed polymer layer as surface treatment. Our method is compatible with the use of the bottom-contact configuration, despite the fact that the polymeric surface treatment does not stand a photolithographic step. Furthermore, we show that our surface treatment results in superior transistor performance.
Substitution reactions of carbon nanotube template
Authors: Li Chi Pui , Chen Ying , Gerald John Fitz
Published: May 2006

Substitution reactions between carbon nanotube (CNT) template and SiO with the formation of carbon rich silicon oxide nanowires (SiO–C-NWs) have been investigated using transmission electron microscopy and x-ray energy dispersive spectroscopy. The reaction was carried out by thermal annealing at 1200°C for 1h of a mixture of silicon monoxide (SiO) and iron (II) phthalocyanine, FeC32N8H16 (FePc) powders. Multiwalled CNTs were produced first via pyrolysis of FePc at a lower temperature (1000°C). SiO vapors reacted with the CNTs at higher temperatures to produce amorphous SiO–C-NWs with a uniform diameter and a length in tens of micrometers. The special bamboolike structure of the CNTs allows the reaction to start from the external surface of the tubes and transform each CNT into a solid nanowire section by section.
Persistence of obligate-seeding species at the population scale: effects of fire intensity, fire patchiness and long fire-free intervals
Authors: Ooi Mark K. J. , Whelan Robert J. , Auld Tony D.
Published: May 2006

Understanding how a species persists under a particular fire regime requires knowledge of the response to fire of individual plants. However, categorising the fire response of a species solely based on known responses of individual plants can be misleading when predicting a population response. In the present study, we sought to determine the fire responses of several Leucopogon species at the population level, including the threatened L. exolasius. We found that, whilst all species studied were obligate seeders, the population responses of species to fire were dependent upon fire intensity and patchiness. Results showed first that low intensity fires were significantly patchier than higher intensity fires. Second, the proportion of plants killed within a population decreased with increased fire patchiness. We also assessed how populations were structured and found that stands were multi-aged at most sites, and did not have a single-aged structure, which is often assumed for obligate seeders. Both spatial complexity within the fire regime leading to adult plant persistence, and inter-fire recruitment, contributed to the multi-aged structure. It is possible that these Leucopogon species are gap recruiters, and may tolerate fire rather than be specifically adapted to it. Inter-fire recruitment may enable L. exolasius populations to persist for a much longer fire-free period than many other species in the region.
Evaluation of synthetic linear motor-molecule actuation energetics
Authors: Brough Branden , Northrop Brian H. , Schmidt Jacob J. , Tseng Hsian-Rong , Houk Kendall N. , Stoddart J. Fraser , Ho Chih-Ming
Published: May 2006

By applying atomic force microscope (AFM)-based force spectroscopy together with computational modeling in the form of molecular force-field simulations, we have determined quantitatively the actuation energetics of a synthetic motor-molecule. This multidisciplinary approach was performed on specifically designed, bistable, redox-controllable [2]rotaxanes to probe the steric and electrostatic interactions that dictate their mechanical switching at the single-molecule level. The fusion of experimental force spectroscopy and theoretical computational modeling has revealed that the repulsive electrostatic interaction, which is responsible for the molecular actuation, is as high as 65 kcal·mol−1, a result that is supported byab initiocalculations.
A hint for the function of human Sco1 from different structures
Authors: Banci Lucia , Bertini Ivano , Calderone Vito , Ciofi-Baffoni Simone , Mangani Stefano , Martinelli Manuele , Palumaa Peep , Wang Shenlin
Published: May 2006

The solution structures of apo, Cu(I), and Ni(II) human Sco1 have been determined. The protein passes from an open and conformationally mobile state to a closed and rigid conformation upon metal binding as shown by electrospray ionization MS and NMR data. The metal ligands of Cu(I) are two Cys residues of the CPXXCP motif and a His residue. The latter is suitably located to coordinate the metal anchored by the two Cys residues. The coordination sphere of Ni(II) in solution is completed by another ligand, possibly Asp. Crystals of the Ni(II) derivative were also obtained with the Ni(II) ion bound to the same His residue and to the two oxidized Cys residues of the CPXXCP motif. We propose that the various structures solved here represent the various states of the protein in its functional cycle and that the metal can be bound to the oxidized protein at a certain stage. Although it now seems reasonable that Sco1, which is characterized by a thioredoxin fold, has evolved to bind a metal atom via the di-Cys motif to act as a copper chaperone, the oxidized form of the nickel-bound protein suggests that it may also maintain the thioredoxin function.
RATES OF POLYPEPTIDE CHAIN ASSEMBLY IN LIVER IN VIVO: RELATION TO THE MECHANISM OF TEMPERATURE ACCLIMATION IN OPSANUS TAU
Authors: Haschemeyer Audrey E. V.
Published: May 2006

A simple translational model, present herein, permits experimental determination of the rates of protein synthesis
in vivo
in terms of a time constant representing the average assembly time of the polypeptide chains. The model has been used to interpret incorporation of radioactive amino acids into toadfish liver fractions as a function of time after hepatic portal vein injection. The results suggest that the increase in liver protein synthesis produced by cold acclimation is due to a more rapid rate of addition of amino acid residues to the growing polypeptide chains. The finding is consistent with the greater aminoacyl transferase activity in livers of cold-acclimated fish.
HYBRIDIZATION OF CHROMOSOMAL RNA TO NATIVE DNA
Authors: Bekhor Isaac , Bonner James , Dahmus Grace Kung
Published: May 2006

Chromosomal RNA, which is associated with chromosomal proteins in the chromosomes of higher organisms, possess the ability to hybridize to homologous native DNA. The proportion of native DNA thus hybridized is similar to the proportion of denatured DNA which hybridizes with chromosomal RNA, and both are similar to the proportions of chromosomal RNA and DNA in native chromatin.
CYCLIC OXONIUM IONS AND RELATED STRUCTURES
Authors: Gargiulo Robert J. , Tarbell D. Stanley
Published: May 2006

This paper describes the preparation by several methods of trialkyloxonium ions containing five-membered rings and the study of their structures by observing the nuclear magnetic resonance (NMR) spectra in several solvents. This provides independent evidence for these compounds, whose existence has been shown by kinetic, preparative, and stereochemical studies.

The following SbCl
6
oxonium salts have been prepared, isolated, and characterized as crystalline solids: the 1,2,5-trimethyltetrahydrofuranium (II
a
), the 1,2,2,5-tetramethyl (II
b
), the
trans
-1-methylperhydrobenzofuranium (IV
a
), the
trans
-1,2-dimethyl (IV
b
), and the
trans
-1,2,2-trimethyl (IV
c
) compounds. The trifluoroacetate salts II
c
, II
d
, IV
d
, and IV
e
have been made in acid solution, and all the salts II and IV have been characterized by their NMR spectra as cyclic oxonium salts, with the charged 1-CH
3
group downfield from an uncharged —OCH
3
. Spectra of all the SbCl
6
salts in nitrobenzene solution are reported. Further evidence for the cyclic structure is given by the identification of 2,2,5-trimethyltetrahydrofuran (VIII) from the action of pyridine and lithium chloride on the 1,2,2,5-tetramethyltetrahydrofuranium salt II
b
. Solvolysis of this salt by ethanol gave 2-ethoxy-2-methyl-5-methoxyhexane (VII) by attack at the tertiary carbon of the oxonium ion. The structure of VII was established by its synthesis and that of the other possible isomer. The trifluoroacetate oxonium ion (IV
e
) gave, after three days in 5 per cent sulfuric-trifluoroacetic acid,
trans
-2,2-dimethylperhydrobenzofuran and methyl trifluoroacetate.
A QUANTITATIVE COMPARISON OF FORMATION OF SPONTANEOUS AND VIRUS-PRODUCED VIABLE HYBRIDS
Authors: Coon Hayden G. , Weiss Mary C.
Published: May 2006

Ultraviolet-inactivated Sendai virus used in conjunction with a selective system reproducibly gives high yields of viable hybrid cell lines. With two different crosses, the frequency of hybrid colonies obtained after virus treatment was found to be 100 times greater than the frequency of spontaneous hybrids, and this increase was found to show little variation between 33 and 1000 hemagglutinating units of virus. No differences have been found between the properties of hybrids obtained after Sendai treatment and those obtained from untreated mixed cultures of parental cells.
ORIGIN AND DIRECTION OF DNA SYNTHESIS IN
E. coli
B/r
Authors: Ward C. B. , Glaser D. A.
Published: May 2006

Replication of the chromosome of
E. coli
B/r has been studied by measuring the change with cell age of the rates of reversion to wild type of auxotrophic markers induced by nitrosoguanidine. Synchronous populations of bacteria were obtained by the procedure of Helmstetter and Cummings. The origin of DNA synthesis was determined to occur at 49 minutes ± 5 minutes on the genetic map, and the direction of synthesis was found to be clockwise.
TRANSLOCATION OF MRNA CODONS, II. PROPERTIES OF AN ANTI-TRANSLOCASE ANTIBODY
Authors: Leder Philip , Skogerson Lawrence E. , Roufa Donald J.
Published: May 2006

A purified preparation of translocase, one of several enzymes required for protein biosynthesis, has been used to prepare a specific anti-translocase antibody. This antibody provides an extremely useful tool not only for detecting the enzyme independent of its activity, but for inhibiting the translocase-mediated reaction and, thus, protein biosynthesis. Though the antibody very rapidly inhibits elongation of the peptide chain, it fails to effect initiation, binding, or peptide bond formation, which strongly suggests that translocase is not a direct participant in these reactions. It also arrests translation of the defined tricodon AUG(U
6
) at the second codon, permitting formation only of the dipeptide, fMet-Phe, rather than the tripeptide, fMetPhe-(Phe)
2
, which is formed in the presence of control serum. We have shown previously that the third codon becomes available only in the presence of translocase, thereby defining the site of action of the antibody. The antibody also has been used to demonstrate that translocase is antigenically distinct from the other proteins required for initiation and protein synthesis in
E. coli
.
VIRUS-INDUCED SARCOMA OF MICE: INHIBITION BY A SYNTHETIC POLYRIBONUCLEOTIDE COMPLEX
Authors: Sarma Padman S. , Shiu Grace , Neubauer Russell H. , Baron Samuel , Huebner Robert J.
Published: May 2006

The availability of a potent inducer of interferon, the synthetic double-stranded RNA (poly I·poly C), prompted us to determine its possible prophylactic and/or therapeutic effect on virus-induced sarcomas of mice. When treatment was begun prior to virus inoculation and repeated on alternate days, the majority of NIH Swiss mice inoculated with Moloney or Friend pseudotypes of Moloney murine sarcoma virus failed to develop tumors. Other experiments suggested that repeated injections initiated even after the establishment of tumor nodules were also effective. Mice injected on the day of birth with poly I·poly C develop high titers of interferon. The evidence favors, but does not establish, the interpretation that the observed tumor inhibition is mediated through the induction of endogenous interferon. These experiments demonstrate that treatment with poly I·poly C is followed by a regression of established murine sarcoma infection in mice.
MEASUREMENT OF LIGAND-INDUCED CONFORMATIONAL CHANGES IN HEMOGLOBIN BY CIRCULAR DICHROISM
Authors: Simon Sanford R. , Cantor Charles R.
Published: May 2006

The UV circular-dichroism spectra of human and horse hemoglobins have been determined at various degrees of partial saturation with oxygen. Spectra of the two native hemoglobins were compared with spectra of the corresponding proteins modified with a reagent known to eliminate the conformational rearrangement normally associated with cooperativity. Such comparison indicates that one region, around 260 mμ, is sensitive chiefly to the state of the hemes; changes in another region, around 285 mμ, may be correlated with the conformational transformation linked to cooperative interactions. All circular-dichroism changes are strictly linear with fractional saturation with oxygen. Possible implications of these results to recently proposed mechanisms for cooperativity in proteins are discussed.
A STATIONARY STATE APPROACH TO RADIATIONLESS TRANSITIONS: RADIATION BANDWIDTH EFFECT ON EXCITATION PROCESSES IN POLYATOMIC MOLECULES
Authors: Rhodes William , Henry Bryan R. , Kasha Michael
Published: May 2006

Excitation processes associated with photon absorption by a molecule are considered in terms of the stationary states of the molecule and the bandwidth of the incident radiation. The conditions of validity of the usual interpretation that transitions occur to excited Born-Oppenheimer states followed by radiationless transitions to other B-O states are examined in terms of the various correlation and relaxation times of the system. In contrast to the usual case, for sufficiently narrow radiation bandwidths, it is demonstrated that excitation should be regarded as occuring to molecular stationary states.
INDEPENDENT VARIATION IN NATURE OF HEMAGGLUTININ AND NEURAMINIDASE ANTIGENS OF INFLUENZA VIRUS: DISTINCTIVENESS OF HEMAGGLUTININ ANTIGEN OF HONG KONG/68 VIRUS
Authors: Schulman J. L. , Kilbourne E. D.
Published: May 2006

Antigenic variations of the two virus-coded surface proteins of influenza virus—hemagglutinin and neuraminidase—were examined in seven strains of influenza A
2
virus (including the Hong Kong/68 strain) isolated from 1957 to 1968. Changes in the two antigens were found to occur independently in nature, resulting in new viruses which differ from older strains more with respect to one antigen than the other. The Hong Kong/68 strain is markedly different from previous A
2
strains in its hemagglutinin antigen but possesses neuraminidase indistinguishable antigenically from that of recent strains. Immunization experiments in mice provided evidence that only the neuraminidase component of an earlier A
2
strain provided protection against Hong Kong virus challenge.

Segregation of hemagglutinin and neuraminidase antigens through recombination of each of the seven strains of influenza A
2
virus with A
0
/NWS virus made it possible to investigate antigenic variation of the two dissociated surface proteins independently in a common plaque assay system. Comparison of these hybrid viruses with the parent A
2
strains provided evidence that all the cross-reactivity of the Hong Kong strain with previous A
2
viruses is explicable on the basis of its similar neuraminidase component. It is proposed that the taxonomy of influenza A viruses must take into account differences in neuraminidase as well as hemagglutinin antigens.
NUCLEAR MAGNETIC RESONANCES OF RECONSTITUTED MYOGLOBINS
Authors: Shulman R. G. , Wüthrich Kurt , Yamane T. , Antonini Eraldo , Brunori Maurizio
Published: May 2006

In proton nuclear magnetic resonance spectra of paramagnetic heme proteins, the resonances of the heme groups are shifted away from those of the many hundred protons of the polypeptide chains by interactions with the unpaired electrons and are therefore well resolved at 220 Mc. This paper describes experiments from which these resolved resonances are assigned to specific protons of the heme group in cyanoferrimyoglobin.

From a comparison with the proton nuclear magnetic resonance spectra of reconstituted cyanoferrimyoglobins and the corresponding cyanoporphyrin iron (III) complexes, the following groups of heme-protons have been assigned to specific resonances in the NMR spectrum of native cyanoferrimyoglobin: the four ring methyls, the four meso protons, the two -CH groups of the vinyls, and the four methylenes of the propionate side chains. Two resonances of intensity one proton have been assigned to the proximal histidyl residue. The only heme protons whose resonances were not observed are the [unk]CH
2
groups of the vinyl groups which are probably buried in the bulk spectrum of the polypeptide chain. The present data indicate that the protein environment is more important in determining the distribution of unpaired electron density in the heme group than are the heme substituents.
AGE RESPONSE TO X-RADIATION OF MURINE LYMPHOMA CELLS SYNCHRONIZED
in vivo
Authors: Mauro F. , Madoc-Jones H.
Published: May 2006

Cells of a transplantable murine lymphoma line were partially synchronized
in vivo
by administration of a single dose of 0.5 mg of hydroxyurea per lymphoma-bearing mouse. At various times after administration of hydroxyurea, the femurs of the lymphomatous mice were X-irradiated, and the number of lymphoma colony-forming units per femur were then assayed by the spleencolony technique. A well-defined age response to irradiation of the lymphoma cells
in vivo
, similar to that of HeLa cells
in vitro
, was observed.
INHIBITION OF THE EFFECTS OF ANGIOTENSIN II ON ADRENAL STEROID PRODUCTION BY DIETARY SODIUM
Authors: Davis Warren W. , Burwell Lawrence R. , Bartter Frederic C.
Published: May 2006

The pressor octapeptide, angiotensin II, can stimulate the production of aldosterone by the adrenal cortex. The present results show that in the dog a high-sodium diet can eliminate the steroidogenic action of angiotensin II, which is thus dissociated from the pressor action which remains.

Angiotensin II was infused intravenously for 48 hours into conscious, undisturbed hypophysectomized dogs that were receiving each day either 60 or 200 mEq of dietary sodium. Blood pressure and secretion of aldosterone, corticosterone, and cortisol were measured (1) throughout the infusion in some dogs, and (2) at the end of the infusion in all dogs. In those dogs receiving 60 mEq of sodium, angiotensin II elevated the blood pressure and produced sustained increases of secretion of aldosterone, corticosterone, and cortisol. In those dogs receiving 200 mEq of sodium, angiotensin II, while retaining its pressor activity, had no effect on the production of aldosterone, corticosterone, or cortisol after 24 hours. Thus, if angiotensin II can produce hypertension clinically, there need not be secondary aldosteronism as well.
GENETIC POLYMORPHISM OF RHESUS THYROXINE-BINDING PREALBUMIN: EVIDENCE FOR TETRAMERIC STRUCTURE IN PRIMATES
Authors: Alper Chester A. , Robin Noel I. , Refetoff Samuel
Published: May 2006

Polymorphism in primate thyroxine-binding prealbumin was investigated with agarose gel electrophoresis at pH 8.6. In the rhesus monkey (
Macaca mulatta
), three forms of this protein were found in random sera: a single rapidly migrating band similar to that in human and other primate sera, a single slowly migrating band cathodal to rhesus albumin, and a five-banded form, the most rapid and slowest bands of which corresponded to the other two forms. The frequencies of occurrence of these three forms were consistent with the hypotheses that rhesus prealbumin is under the control of two codominant autosomal alleles,

PA
F

and

PA
S

, and that the protein occurs naturally in serum as a tetramer composed of similar subunits.

It was possible, by simple mixing
in vitro
, to produce five-banded prealbumin patterns from rhesus PA SS serum and rhesus PA FF serum,
M. arctoides
serum,
P. hamadryas
serum, and human serum. Thyroxine was bound by all the hybrid molecules produced in this fashion.
DIFFERENTIATION OF MAMMALIAN SOMATIC CELLS: DNA AND HEMOGLOBIN SYNTHESIS IN FETAL MOUSE YOLK SAC ERYTHROID CELLS
Authors: De La Chapelle Albert , Fantoni Antonio , Marks Paul A.
Published: May 2006

The relationship between the synthesis and replication of DNA and the capacity to synthesize specialized protein on a stable messenger RNA has been examined in yolk sac erythroid cells differentiating
in vivo
in fetal mice. Evidence is presented that by day 11 of gestation, at least 98 per cent of yolk sac erythroid cells are synthesizing hemoglobin. These cells are shown to incorporate
3
H-thymidine and to replicate, with more than twofold increase in cell number between days 10 and 11. Division of these cells continues through day 13. Hemoglobin formation in these cells is resistant to actinomycin D from day 10. During this period, ribosomal content per cell decreases by more than a factor of 2. These data indicate that in yolk sac erythroid cells, hemoglobin formation proceeds independent of continued RNA formation in cells capable of DNA synthesis and replication.
WILDER MANIFOLDS ARE LOCALLY ORIENTABLE
Authors: Bredon Glen E.
Published: May 2006

A proof is given for the long-standing conjecture of R. L. Wilder that every generalized manifold is locally orientable. Roughly speaking, a generalized
n
-manifold is a locally compact space whose local homology groups at each point are those of an
n
-manifold. Local orientability is a condition in which the local homology groups at neighboring points have a certain nice relationship to one another. Local orientability is indispensable for almost all applications.
FLUOROMETRIC QUANTITATION OF FLUORESCEIN-COUPLED ANTIBODIES ATTACHED TO THE CELL MEMBRANE
Authors: Strom Roberto , Klein Eva
Published: May 2006

A method was devised which allows the measurement, by direct and indirect fluorescence assay, of the binding of fluorescein-coupled antibodies directed against cell-membrane antigens. The systems used were: (1) species-specific antigens, (2) genetically determined isoantigens, (3) virus-determined, tumor-specific antigens, and (4) membrane-bound immunoglobulin in a Burkitt cell line. Titration of antibodies gave straight lines in the log versus log scale, the slope of the titration curve probably being dependent on the density of antigen receptors on the cell surface.
THE RATE OF MOLECULAR EVOLUTION CONSIDERED FROM THE STANDPOINT OF POPULATION GENETICS
Authors: Kimura Motoo
Published: May 2006

The rate of amino acid substitutions in the evolution of homologous proteins is remarkably constant. Furthermore, estimated rates of amino acid substitutions based on comparisons of the alpha hemoglobin chains of various mammals with that of the carp are about the same as those based on comparisons of the carp alpha and mammalian beta or the alpha and beta chains in mammals. These uniformities are regarded as evidence for the hypothesis that a majority of amino acid substitutions that occurred in these proteins are the result of random fixation of selectively neutral or nearly neutral mutations.

Two implications of this possibility are discussed: (
a
) Random gene frequency drift is playing an important role in determining the genetic structure of biological populations and (
b
) genes in “living fossils” may be expected to have undergone as many DNA base (and therefore amino acid) substitutions as corresponding genes (proteins) in more rapidly evolving species.
ACETYLCHOLINE AND ITS THIOLESTER AND SELENOLESTER ANALOGS: CONFORMATION, ELECTRON DISTRIBUTION, AND BIOLOGICAL ACTIVITY
Authors: Shefter Eli , Mautner Henry G.
Published: May 2006

The crystal structures of acetylthiolcholine bromide and propionylthiolcholine iodide were elucidated. Acetylthiolcholine was found to be essentially isosteric with acetylselenolcholine, while the conformation of these compounds was quite different from that of acetylcholine.

The importance of conformation and electron distribution in the biological actions of choline esters is discussed.
PARTIAL PURIFICATION OF NATIVE RRNA AND TRNA CISTRONS FROM
Mycoplasma
SP. (KID)
Authors: Ryan John L. , Morowitz Harold J.
Published: May 2006

Precise optical melting profiles of purified DNA from
Mycoplasma
sp. (Kid) show a secondary hyperchromic rise, corresponding to 1.4 per cent of the total DNA, occurring at 88°C, while the bulk of the DNA melts at 79.5°C, indicating an average base composition of 24.9 per cent guanine-cytosine (G-C). A method is presented, using sonication followed by hydroxyapatite column chromatography, for the partial purification of regions of a genome which contain significantly higher G-C than the average value for the genome. The procedure does not involve denaturation and renaturation of the high G-C material so that purified DNA is in its native, double-stranded state and has a normal melting profile. When applied to
Mycoplasma
sp. (Kid), the method yielded a fraction of native DNA enriched 40 times with respect to those regions coding for rRNA and tRNA. This enriched DNA has a saturation hybridization value of 15.9 per cent with Kid rRNA plus tRNA. The saturation hybridization values of the bulk DNA with rRNA and tRNA are 0.26 per cent and 0.16 per cent, respectively. Based on a genome size of 6.84 × 10
8
, obtained by electron microscopy, this indicates that
Mycoplasma
sp. (Kid) contains only enough ribosomal DNA to code for one set of 23
S
plus 16
S
rRNA and only enough DNA complementary to tRNA to code for 44 different tRNA molecules.
THE AMINO ACID SEQUENCE OF BOVINE CARBOXYPEPTIDASE A
Authors: Bradshaw Ralph A. , Ericsson Lowell H. , Walsh Kenneth A. , Neurath Hans
Published: May 2006

The amino acid sequence of the four fragments produced by treatment of bovine carboxypeptidase A with cyanogen bromide has been completed. The alignment of these fragments, previously established by peptic digest of the whole protein, allows for the description of the complete primary structure of the molecule. A comparison of the proposed functional residues, identified by X-ray diffraction analyses, has either confirmed their assignments or provided their correct identity. The functional and structural residues of principal importance include Arg 145, Tyr 248, and Glu 270 as the binding site of the substrate carboxyl group, the proton donor, and the nucleophilic moiety, respectively, which were correctly assigned; His 196 as the third zinc ligand and Tyr 265 as the binding site of the α-carboxyl group have been corrected from their original X-ray assignments. The other two zinc ligands, His 69 and Glu 72, were identified previously from chemical and X-ray studies. The assignment of the two half-cystinyl residues and the postulation of the existence of a disulfide bond have been confirmed.