bluuebunny/crossref_metadata_2025 huggingface dataset:
Nucleocytoplasmic Shuttling of the Golgi Phosphatidylinositol 4-Kinase Pik1 Is Regulated by 14-3-3 Proteins and Coordinates Golgi Function with Cell Growth
Authors: Demmel Lars , Beck Mike , Klose Christian , Schlaitz Anne-Lore , Gloor Yvonne , Hsu Peggy P. , Havlis Jan , Shevchenko Andrej , Krause Eberhard , Kalaidzidis Yannis , Walch-Solimena Christiane
Published: January 2008

The yeast phosphatidylinositol 4-kinase Pik1p is essential for proliferation, and it controls Golgi homeostasis and transport of newly synthesized proteins from this compartment. At the Golgi, phosphatidylinositol 4-phosphate recruits multiple cytosolic effectors involved in formation of post-Golgi transport vesicles. A second pool of catalytically active Pik1p localizes to the nucleus. The physiological significance and regulation of this dual localization of the lipid kinase remains unknown. Here, we show that Pik1p binds to the redundant 14-3-3 proteins Bmh1p and Bmh2p. We provide evidence that nucleocytoplasmic shuttling of Pik1p involves phosphorylation and that 14-3-3 proteins bind Pik1p in the cytoplasm. Nutrient deprivation results in relocation of Pik1p from the Golgi to the nucleus and increases the amount of Pik1p–14-3-3 complex, a process reversed upon restored nutrient supply. These data suggest a role of Pik1p nucleocytoplasmic shuttling in coordination of biosynthetic transport from the Golgi with nutrient signaling.
Functionally distinct regulatory RNAs generated by bidirectional transcription and processing of microRNA loci
Authors: Tyler David M. , Okamura Katsutomo , Chung Wei-Jen , Hagen Joshua W. , Berezikov Eugene , Hannon Gregory J. , Lai Eric C.
Published: January 2008

Many microRNA (miRNA) loci exhibit compelling hairpin structures on both sense and antisense strands; however, the possibility that a miRNA gene might produce functional species from its antisense strand has not been examined. We report here that antisense transcription of the Hox miRNA locus mir-iab-4 generates the novel pre-miRNA hairpin mir-iab-8, which is then processed into endogenous mature miRNAs. Sense and antisense iab-4/iab-8 miRNAs are functionally distinguished by their distinct domains of expression and targeting capabilities. We find that miR-iab-8-5p, like miR-iab-4-5p, is also relevant to Hox gene regulation. Ectopic mir-iab-8 can strongly repress the Hox genes Ultrabithorax and abdominal-A via extensive arrays of conserved target sites, and can induce a dramatic homeotic transformation of halteres into wings. We generalize the antisense miRNA principle by showing that several other loci in both invertebrates and vertebrates are endogenously processed on their antisense strands into mature miRNAs with distinct seeds. These findings demonstrate that antisense transcription and processing contributes to the functional diversification of miRNA genes.
Conditional forebrain deletion of the L-type calcium channel CaV1.2 disrupts remote spatial memories in mice
Authors: White Jessica A. , McKinney Brandon C. , John Manorama C. , Powers Patricia A. , Kamp Timothy J. , Murphy Geoffrey G.
Published: January 2008

To determine whether L-type voltage-gated calcium channels (L-VGCCs) are required for remote memory consolidation, we generated conditional knockout mice in which the L-VGCC isoform CaV1.2 was postnatally deleted in the hippocampus and cortex. In the Morris water maze, both CaV1.2 conditional knockout mice (CaV1.2cKO) and control littermates displayed a marked decrease in escape latencies and performed equally well on probe trials administered during training. In distinct contrast to their performance during training, CaV1.2cKO mice exhibited significant impairments in spatial memory when examined 30 d after training, suggesting that CaV1.2 plays a critical role in consolidation of remote spatial memories.
The histone deacetylase inhibitor valproic acid enhances acquisition, extinction, and reconsolidation of conditioned fear
Authors: Bredy Timothy W. , Barad Mark
Published: January 2008

Histone modifications contribute to the epigenetic regulation of gene expression, a process now recognized to be important for the consolidation of long-term memory. Valproic acid (VPA), used for many years as an anticonvulsant and a mood stabilizer, has effects on learning and memory and enhances the extinction of conditioned fear through its function as a histone deacetylase inhibitor (HDAC). Here we report that VPA enhances long-term memory for both acquisition and extinction of cued-fear. Interestingly, VPA enhances extinction, but also enhances renewal of the original conditioned fear when tested in a within-subjects design. This effect appears to be related to a reconsolidation-like process since a single CS reminder in the presence of VPA can enhance long-term memory for the original fear in the context in which fear conditioning takes place. We also show that by modifying the intertrial interval during extinction training, VPA can strengthen reconsolidation of the original fear memory or enhance long-term memory for extinction such that it becomes independent of context. These findings have important implications for the use of HDAC inhibitors as adjuncts to behavior therapy in the treatment of phobia and related anxiety disorders.
Carboniferous crustaceans
Authors: CLARKSON E.N.K.
Published: January 2008

Higher crustaceans of distinctly modern type first diversified in the Lower Carboniferous. Some, from Scottish and Northern English localities, are exquisitely preserved, so that much can be inferred about their biology. Yet they seem to have been environmentally restricted, confined to close inshore marine fades and to lagoons and ponds of reduced, salinity. For all their apparent modernity, no Carboniferous crustaceans ever developed pincer–like claws, so common in modern types. Might this have been one of the factors that limited them?
Limestone depositional sequences on shelves and ramps: modern and ancient
Authors: AHR WAYNE
Published: January 2008

Environmental processes such as tides, waves, storms, drought and flood leave tell–tale responses in sedimentary deposits. Careful study of modern environments and their standard depositional sequences has led to sophisticated reconstruction of ancient sedimentary environments. Only recently have ‘ideal’ carbonate rock sequences been constructed and used to interpret geological history. When the lateral array of contemporaneous carbonate sequences is known, it becomes possible to trace the evolutionary history of continents and ocean basins.
Geology on the moons of Uranus
Authors: ROTHERY DAVID A.
Published: January 2008

In January 1986 the spaceprobe Voyager‐2 revealed details of the surfaces of the icy satellites of Uranus for the first time, including grabens, other faulted features, impact craters and possible ice flows. Despite their apparent similarity to some of the moons of Jupiter and Saturn, they highlight many new questions as to the evolution of, and interactions between, such bodies.
English Jurassic dasyclads: seaweed indicators of marine climate
Authors: ELLIOTT GRAHAM F.
Published: January 2008

Aragonitic chlorophyte (green) algae, typical of the warm seas of the Tethyan area, reached as far north as the present Cotswolds of Southern England in mid‐Jurassic times, when conditions made colonisation possible. Few in numbers and species, they appear to show features similar to those of their living descendants found today in warm seas marginal to the tropics, so confirming the Jurassic palaeolatitude arrived at independently from palaeogeographical studies.
A new look at rifts
Authors: FROSTICK LYNNE , REID IAN
Published: January 2008

Rift valleys have always enthralled geologists. They are the rents in the Earth's crust produced when continental plates pull apart. Besides telling us something about the evolution of our planet, they also act as topographic sumps in which parts of the sedimentary record of Earth history are often best preserved. Yet our understanding of how, where, and why rifts form has only recently come of age with new models of structure and sedimentation.
Magnetostratigraphy
Authors: TURNER PETER
Published: January 2008

Magnetostratigraphy involves the study of changes in the Earth's magnetic field that are recorded in sediments and rocks. These include short‐term fluctuations (secular variation), polarity transitions and magnetic reversal sequences. All have important applications in the Earth sciences. They can be used to calculate the rates of sea‐floor spreading and sediment deposition rates, and for time‐correlation of rock sequences, especially when no other means are available.
Neotectonics
Authors: HANCOCK PAUL L.
Published: January 2008

Neotectonics is the study of Earth movements of late Cenozoic age, especially those in harmony with contemporary horizontal and vertical crustal motions. Precise information about the character, frequency and rate of recent movements is an essential part of planning how to reduce earthquake hazard, and it also allows tectonicians to devise realistic models of crustal behaviour.
When downhole logging turns to geochemistry
Authors: LOVELL MIKE , ANDERSON ROGER
Published: January 2008

The procedure of lowering geophysical instruments down boreholes on a wire has, over the past 60 years, been a useful aid in defining the physical nature of the rock formations through which the borehole passes. Current developments, however, herald the advent of the use of such techniques for the measurement of geochemical concentrations in a quantitative way. This opens the door to a whole new series of applications in a wide range of geological disciplines.
The face of the trench
Authors: OKADA HAKUYU
Published: January 2008

The deep‐sea trenches that occur between unstable chains of volanic arcs and the ocean floor attract great interest because they are the most inaccessible areas of our planet. Now, direct observations of trench faces have become possible by using deep‐sea submersibles. This article describes features of the Nankai Trough and the Japan and Kuril Trenches at depths of up to 6000 m.
Tufa: a freshwater limestone
Authors: FORD TREVOR D.
Published: January 2008

Tufa, or travertine, is a deposit of calcium carbonate precipitated with the loss of carbon dioxide from springs or streams saturated with calcium bicarbonate. Algae or bacteria may assist in this process, which is favoured by raised temperatures. British and overseas examples of tufa deposits show various features including their role in damming up lakes.
Sandwiched fossils
Authors: TAYLOR PAUL D. , TODD JON A.
Published: January 2008

A little‐known mode of fossil preservation‐bioimmuration‐is responsible for exciting new findings of soft‐bodied organisms. Bioimmuration results from organic overgrowth by animals such as serpulid worms and oysters which form natural moulds of the organisms they have overgrown on their undersurfaces or sandwich overgrown organisms between themselves and their substrate. Overgrowth is a routine occurrence among the many marine organisms lacking mobility, and bioimmured fossils can be extremely common. Discoveries of bioimmured ctenostome bryozoans, hydroids and other soft‐bodied animals that lived attached to hard surfaces are providing important new palaeontological perspectives, especially in the Mesozoic.
Changing sea levels and erupting volcanoes: cause and effect?
Authors: McGUIRE W. J.
Published: January 2008

The Quaternary period was characterized not only by significant cyclic changes in global temperature but also by increased explosive volcanism. Is this just coincidence or is there a connection? And if the latter, what is it? A number of possible mechanisms have been proposed to explain how these two apparently unrelated phenomena may be related, most involving the climatic effects of volcanic debris ejected into the atmosphere. A new model, however, proposes that changing sea levels during the last Ice Age may also have had an important role to play in this problematical scenario.
Fossil fuels: a crisis of resources or effluents?
Authors: WOODCOCK NIGEL H.
Published: January 2008

Most professional geologists are employed to find oil, gas and coal. They work for a society constantly concerned about future supplies of fossil fuels. Yet now the global atmospheric pollution from burning these fuels threatens to harm society sooner than any shortage of resources. Caught amidst the fossil fuel debate, how should geologists respond?
The dowsing rod: a most contentious instrument
Authors: MILLS ALLAN
Published: January 2008

'Since this matter remains in dispute and causes much dissention amongst miners, I consider it ought to be examined on its own merits.’–Georgius Agricola.
Jurassic lagoon: salt or soup?
Authors: MILSOM CLARE , SHARPE TOM
Published: January 2008

The 140‐million‐year‐old Solnhofen lithographic limestone of Bavaria, famous for the remarkable preservation of the earliest bird, Archaeopteryx, is one of the most acclaimed fossil horizons on Earth. Understandably, interest has focused on the more glamorous fossil finds from these rocks; the most common macrofossil, a small sea lily, has been neglected. However, this unprepossessing animal is a key player in the Solnhofen story.
Early development of the glacial theory: Louis Agassiz and the Scottish connection
Authors: GORDON JOHN E.
Published: January 2008

Britain's landscape reflects the imprint of glaciation and the dramatic fluctuations in climate that have characterized the Quaternary. There was an important Scottish connection in the early development of the glacial theory during the nineteenth century, in particular through the work of Louis Agassiz.
Paving the way for conservation?
Authors: BENNETT ANDREW F. , BENNETT MATTHEW R. , DOYLE PETER
Published: January 2008

Limestone pavement is a unique part of Britain's physical landscape. Along with other forms of naturally weathered rock, it is under threat from exploitation for the horticultural market. Valued for its delicate and sculptured form, limestone pavement has been frequently used as decorative stone in rockeries and other landscaped ground. If this unique landscape is to be protected, its exploitation must stop. Yet it must be remembered that the use of rock in gardens and landscaped ground has an important role in raising the public profile of geology within urban areas. We have a simple message: the use of limestone pavement is wrong and must stop, but the use of other forms of stone in urban gardens is beneficial for the Earth sciences.
PHOTOCHEMISTRY OF 4‐AMINOPYRIMIDINES 2,6‐DIMETHYL‐4‐AMINOPYRIMIDINE
Authors: Wierzchowski K. L. , Shugar D.
Published: January 2008

Abstract— Ultraviolet irradiation (2537 Å) of 2,6‐dimethyl‐4‐aminopyrimidine (I) results in an intramolecular rearrangement with the formation, either in aqueous or anyhdrous medium, of only one photoproduct, 2‐amino‐3‐cyanopent‐2‐enemine (II), in quantitative yield. The quantum yield for this reaction is 0.043 einsteins/mole.

Deamination of II gives, quantitatively, 2‐amino‐3‐cyanopent‐2‐en‐4‐one (III) and this, in turn, may be deaminated to give, quantitatively, 3‐cyanopent‐2‐en‐2‐01‐4‐0ne (cyanoacetyl‐acetone, IV). Identification of II was achieved initially through isolation of III and IV. Some of the chemical and physico‐chemical properties of these compounds are reported, as well as methods for obtaining all of them on a preparative scale.

The mono‐protonated form of I also gives II on irradiation, but in lower quantum yield, 7.3times108 einsteins/mole. Irradiation of the doubly protonated form of I in strongly acid medium leads directly to the formation of a mixture of II, III and IV, with approxi mately the same quantum yield.

The possible mechanisms for the foregoing photochemical reactions are discussed and their significance related to the photochemistry of 4‐aminopyrimidines in general and to those of nucleic acid derivatives in particular.
SOME EFFECTS OF LIGHT ON LEAF GROWTH IN PISUM SATIVUM AND TROPAEOLUM MAJUS
Authors: Sale P. J. M. , Vince D.
Published: January 2008

Abstract— The effect of wave‐length of light on leaf expansion in Tropaeolum majus‘Double Orange Gleam’ and Pisurn sativum‘Meteor’ has been studied. In both species leaf growth is strongly promoted by light.

Increasing the daily duration of exposure to light increased leaf expansion in Tropueolum in both blue and red wave‐bands over a range of light intensities. In Pisum a similar effect of ail increase in duration of irradiation was found over the whole range of intensities used for blue light but only at the highest intensity for red light: at the two lower intensities in red an increase in duration of the light treatment beyond 1 hr did not increase leaf expansion.

In both species a period of 4 hr of blue followed by 4 hr of red promoted leaf growth more than 4 hr of red followed by 4 hr of blue. The effect of a 4 hr period of red light was largely prevented when it was followed by far‐red; the effect of 4 hr of blue light, on the other hand, was not affected by subsequent exposure to far‐red.

It is concluded that leaf growth in Pisum and Tropaeolum is dependent not only on the ‘low‐energy’ red/far‐red reversible reaction but also on one or more ‘high‐enerFy’ photo‐reactions.
DIFFERENTlAL REACTIVITY OF EXCITED SINGLETS AND TRIPLETS*
Authors: Rosenberg J. L.
Published: January 2008

Summary Experimental data from the oxygen quenching of excited states, from the acidities of excited states, and from the kinetics of photosynthesis indicate that the lowest excited singlet and the lowest triplet states of aromatic molecules may not have the same reactivity.

The reasons for these differences may be connected with the energy deficit of triplets, with spin conservation rules, with differences in the nuclear geometry, or with differences in the electronic configuration or polarizability. With improved theoretical representations of excited states, the observed differences in reactivity may serve to increase our understanding of the nature of primary photochemical events.
THE INACTIVATION OF ENZYMES BY ULTRAVIOLET LIGHT,‐IV. THE NATURE AND INVOLVEMENT OF CYSTINE DISRUPTION*
Authors: Augenstein Leroy , Riley Penelope
Published: January 2008

Abstract Two divergent theories of the mechanisms involved in U.V. inactivation of enzymes have been developed over a period of years. The one proposes that the random destruction of any amino acid residue causes inactivation. The second emphasizes the importance of the disruption of a cluster of specific cystines and hydrogen bonds responsible for the spatial integrity of the active center. Consistent with the latter postulates, previous studies in this series have shown that the number of cystines disrupted in trypsin is correlated with loss in enzymic activity and in ribonuclease the disruption of cystines is very non‐random. In the present experiments only 1–1.1 titrable (with pCMB) SH groups are formed for each cystine disrupted. The available evidence suggests that about 0.1 of the disrupting events produce two SH groups: 0.2 lead to the formation of one ‐SH and one ‐SOnH: and about 0.7 involve the cleavage of a C‐S bond with the appearance of one ‐SH plus an oxide (perhaps ‐C = O) of the C moiety. The disruption of cystine is such that neither serine, alanine, glycine nor H2S is formed in large amounts. The kinetics of SH production emphasize that the various cystines in RNase and trypsin have unequal radiation sensitivities; some must differ by at least a factor of 10. Tentatively it is concluded that u.v. absorbed directly by cystines (ca 20 per cent) causes random, symmetric breakage of S‐S, whereas quanta absorbed in aromatic residues (ca 80 per cent) lead to efficient energy transfer and localization in chromophores adjacent to critical cystines followed by addition of hydrogen to specific C‐S bonds resulting in their cleavage.
A SENSITIVE METHOD FOR DETERMINING CHLOROPHYLL b IN PLANT EXTRACTS
Authors: Ogawa Teruo , Shibata Kazuo
Published: January 2008

Abstract— A new method of using hydroxylamine as the reagent was developed to determine the concentrations of chlorophylls a and b in plant extracts accurately and sensitively. The method is based on the principle that hydroxylamine reacts in a short time with the aldehyde group of chlorophyll b in 95 per cent methanol at pH 5.8 to afford a derivative having a red band similar in position to the red band of chlorophyll a, while the spectrum of chlorophyll a is unaffected by the treatment with hydroxylamine. The method includes the measurements of absorbanlce for the mixture of a plant extract with hydroxylamine and for the reagent blank at a single wavelength, 666 mμ, and the concentrations of chlorophylls a and b are calculated from the absorbance value for the reagent blank and the increment of absorbance due to the reaction. By measuring this increment directly by difference photometry, one can determine a low concentration of chlorophyll b relative to chlorophyll a. The contents of chlorophylls in matured and etiolated leaves were determined by the method, and the errors included in this method were shown to be smaller than those in a commonly used technique including the measurements at two different wavelengths.
IN ACTIVATION OF A STRAIN OF TOBACCO NECROSIS VIRUS AND OF THE RNA ISOLATED FROM IT, BY ULTRAVIOLET RADIATION OF DIFFERENT WAVE‐LENGTHS
Authors: Kassanis B. , Kleczkowski A.
Published: January 2008

Abstract— A train of tobacco necrosis virus (TNV) and infective nucleic acid isolated from it (TNV‐RNA) are equally susceptible to inactivation by U.V. radiation at all wave‐lengths tested (230‐290 mμ) and can be photoreactivated to the same extent by exposing inoculated host plants to daylight. The shape of the action spectrum for inactivation by U.V. of TNV and of TNV‐RNA follows that of the absorption spectrum of TNV‐RNA. Thus, unlike the RNA of tobacco mosaic virus, the RNA of TNV behaves in all these respects in the same way irrespective of whether it is inside or outside the virus particle. To inactivate TNV or TNV‐RNA to 50 per cent of their original infectivities, each mg of RNA must absorb about 0.27 joules of radiation energy of any wave‐length between 230 and 290 mp, which corresponds to a quantum yield of about 0.65 ×10‐3 at 260 mμ.
PHOTOINHIBITION OF CHLOROPLAST REACTIONS
Authors: Kok Bessel , Gassner Edward S. , Rurainski Hans J.
Published: January 2008

Abstract— An attemlpt was made to localize the site of photoinhibition of photosynthesis by measuring the decay of various chloroplast reactions after exposure to very strong light. A11 substrate reductions coupled to oxygen evolution as well as photophosphorylation mediated by PMS, proved equally sensitive to photoinhibition. Reactions involving only the long wave photosystem, such as TPN reduction with ascorbate as electron donor and photooxidation of cytochromec by detergent‐treated chloroplasts were sensitive to a lower degree.

Photoinhibition irreversibly annihilated the ‘variable’ fraction of fluorescence emission —it decreased the steady state yield 2‐3 fold and abolished the slow rise of the emission at the onset of illurnination.

It is concluded that the primary site of light inactivation is in, or close to, the trapping centers of the oxygen evolving step of photosynthesis. Pre‐illumination leaves these traps in a state capable of draining light from sensitizing pigments but unable to perform useful photochemistry.
U.V.‐DOSAGE MEASUREMENT IN A GEOMETRICALLY COMPLEX SYSTEM WITH LIGHT‐SENSITIVE PAPER. QUANTUM YIELD FOR SALMONELLA KILL IN EGG WHITE
Authors: Launer Herbert F. , Hammerle Olivia O.
Published: January 2008

Abstract— Simple measurement of germicidal (2537 Å) u.v. in a geometrically complex system is described. The radiant energy incident upon thin egg white films in a rapidly spinning centrifuge was integrated over time periods with NBS light‐sensitive paper. The radiant killing of contaminant Salmonella was found to be one microorganism per 1011 quanta absorbed by the medium.
TRIPLET STATE STUDIES OF FLAVlNS BY ELECTRON PARAMAGNETTC RESONANCE‐III
Authors: Shiga T. , Piette L. H.
Published: January 2008

Abstract— A continuation of studies is presented on the excited triplet state of flavins using EPR techniques. Detailed experiments are reported on the triplet state of flavin‐mono‐nucleotide (FMN) and flavin‐adenine‐dinucleotide (FAD). Action spectra of triplet yield are explained in terms of the optical absorption for FMN and FAD. Effects of light saturation, concentration quenching and oxygen on the triplet state are discussed. It is suggested that the rate constant k3 for the intersystem crossover from the excited singlet to the triplet state is increased by oxygen and quenchers such as KI. Detailed kinetic studies are presented on the formation of the triplet state.
THE RED EMISSION BANDS OF MOLECULAR OXYGEN
Authors: Arnold J. S. , Browne R. J. , Ogryzlo E. A.
Published: January 2008

Abstract— The temperature dependence and the absolute emission intensity of the 6340 Å band of molecular oxygen have been measured. The results indicate that the emitting pair of molecules is not bound and possesses a radiative half life of about 25 msec. The implications of these results on some chemiluminescent reactions are discussed.
ACTION DE LA LUMIÈRE SUR LA CROISSANCE DES TIGES PRINCIPALES DE L‘ASPARAGUS MEDEOLOIDES
Authors: Courtot Y.
Published: January 2008

Abstract— Studies of the influence of light upon the growth of Asparagus medeoloides main stems show that the stem‐length and the time‐growth increase when the intensity of illumination decreases. There is no direct proportionality between growth and illumination intensity; a maximum is found at 660 lx.
ACTION DE LA QUANTITÉ JOURNALIÈRE DE LUMIÈRE SUR LA FLORAISON, LE POIDS SEC ET LA TENEUR EN EAU DE QUELQUES PLANTES DE JOURS COURTS ET DE JOURS LONGS
Authors: Bouillenne R.
Published: January 2008

Abstract— Experiments were carried on in the Liège Phytotron for two years to discover what reactions could be obtained when both short‐day and long‐day plants were placed in the same light energy per day (light intensity × daily light duration in various combinations) and receiving respectively 8 or 16 hr light per day. It was observed that both types of plants give parallel dry weight curves in both long‐day and short‐day, but this happens only during the vegetative state following germination.

Differences occur in those dry weight curves in short‐day plants and also in long‐day plants when cultivated under inductive photoperiodic light and induced to flower.

In these suitable light conditions, their dry weight increased compared with that of plants left in a non‐inductive photoperiodic fight.

The evolution of tissue water content (stems, leaves, flowers), expressed as water % of the dry weight, is also interesting to observe in the same experimental environments. This evolution plays an important physiological part in flower formation, as has been shown before by R. Bouillenne.

Both types of plants cultivated in their respective non‐inductive light point out a very simple curve of water content. First a rapid increase of water into the tissues during the first 10 days after germination; then from this maximum, the curve goes down regularly and slowly till a constant low level.

However, in inductive light exposure, water content percentage curves are really different for both types of species. Considering the same daily value of light energy given in each case, it is possible to conclude that the induction of flower does not depend on the daily light quantity but on something else which is connected with the photoperiodism.

These fluctuations of the water content will be investigated.
EFFECT OF U.V.‐IRRADIATION ON SEDIMENTATION BEHAVIOR OF VARIOUS PROTEINS
Authors: Dose Klaus , Sena Luigi
Published: January 2008

Abstract— Moderate u.v.‐doses (2537 Å) sufficient to reduce enzymatic activities of native enzymes up to about 90 per cent, in general do not produce measurable amounts of smaller dialyzable fragments.

The disappearance of the original boundary in sedimentation diagrams is mostly due to the formation of rapidly sedimenting polydispersed material. Generally the sedimentation constants of the native proteins are not significantly changed. The boundaries, however, often loose their symmetry. The quantum yields for the disappearance of the original boundaries are roughly inversely proportional to the molecular weights. The number of molecules disappearing from the main peak is smaller than the number of molecules inactivated by a given dose. The data indicate that ultracentrifugation provides no satisfactory method for separation of native molecules from the damaged and inactivated. Proteins with labile quaternary structures (e.g. thyroglobulin or hemocyanine) which tend to dissociate under very mild conditions show an enhanced dissociation after u. v.‐irradiation.
PHOTOCHEMISTRY OF BIOLOGICAL MOLECULES – II. PHOTOLYSIS OF DIPEPTIDES IN THE SOLID STATE
Authors: Johns R. B. , Looney F. D. , Whelan D. J.
Published: January 2008

Abstract— Photolysis with light of 2537 Å of a series of aliphatic dipeptides in the solid state has been shown to lead to bond rupture and free radical formation. The structures of the radicals have been determined by ESR techniques and in general, the free electron has been shown to reside on the carbon atom attached to the nitrogen atom of the peptide bond. Dipeptides containing phenylalanine residues show ESR spectra typical of the free amino‐acid in the terminal position.
PHOTOCHEMISTRY OF A MACROMOLECULE: TOBACCO MOSAIC VIRUS
Authors: Mclaren A. D.
Published: January 2008

Abstract— A history of the photochemistry of the first known virus is presented. Hollaender and Duggar recognized that the virus contains nucleic acid because of the shape of their action spectrum for photoinactivation. An analysis of this spectrum in detail presents a challenge to photochemists because of the combined role of protein and nucleic acid in determining rates of inactivation. At present these rates can not be explained simply on the basis of the photochemistry of each of the constituents; that is, the photochemistry of free infectious nucleic acid differs in several respects from that exhibited by nucleic acid irradiated in intact virus. At present it is believed that pyrimidine hydrate and dimer formations are important, but an explicit solution to the problem is not in sight.
DOSIMETRY IN PHOTOCHEMISTRY*
Authors: Johns H. E.
Published: January 2008

Abstract— A method of dosimetry which is useful in analyzing complex photochemical reactions involving more than one photoproduct is described. This involves determining a photochemical cross section for each of the products, σB, σc…., and an absorption cross section σ. for the reacting species. The ratio σB/σa is the quantum yield for production of product B. Where a number of photoproducts are produced simultaneously, it is convenient to express ‘dose’ in terms of the average number of photons per cm2‘seen’ by each molecule in the vessel. This average can be calculated from the number of incident photons, the volume of the liquid, the absorbance and the path length. Experimental details of the irradiation facility which is convenient for such studies are presented. The method of dosimetry is illustrated using photochemical data for uracil and orotic acid in solution.
INTERSYSTEM CROSSING AND DIMERIZATION IN AQUEOUS SOLUTIONS OF URACIL AND OROTIC ACID
Authors: JOHNS H. E.
Published: January 2008

Un analisis cinético de la fotoquímica en el u.v. de uracilo y ácido orótico muestra que el hidrato se forma a partir del estado singulete, mientras que el dímero lo hace a partir del estado triplete. El rendimiento cuantico de la formación del hidrato es independiente de la longitud de onda de irradiación, mientras que el rendimiento cuántico de la formación de triplete aumenta a longitudes de onda menores. Se presenta además una explicación para el aumento de “intersystem crossing” a altos niveles de excitación basada en la presen‐cia de tautomeros.
EVIDENCE OF REACTIVE INTERMEDIATES IN SECO/CYCLO ISOMERIZATIONS BY LOW‐TEMPERATURE TECHNIQUES
Authors: QUINKERT G.
Published: January 2008

Abstract— Matrix isolation methods at low temperatures have been used to trap seco‐isomeric intermediates in photochemical electrocyclic transformations of cyclo isomers. The stereochemical behavior is found to be consistent with the Woodward‐Hoffman rules.

Se han usado soluciones a bajas temperaturas para atrapar intermediaries seco‐isoméricos en transformacíones fotoquímicas electrocíclicas de cicloisómeros. Se ha encontrado que el comportamiento estereoquímico es consistente con las reglas de Woodward y Hoffmann.
PHOTOADDITION OF ALCOHOLS TO PURINE*
Authors: CONNOLLY JOHN S. , LINSCHITZ HENRY
Published: January 2008

Abstract— A new photoreaction is described, in which alcohols add to purine. The adducts of methanol, ethanol (two isomers), and isopropanol have been isolated and characterized by chemical analysis, and their u.v., i.r., NMR and mass spectra. Mainly on the basis of the NMR data and using deuterated‐purine adducts, it is shown that the addition involves bonding between the α‐carbon of the alcohol and the 6‐carbon of the purine ring. The quantum yield of the reaction, at 254 ran, is about 0·2 in dry, deoxygenated methanol, ethanol or isopropanol. The reaction appears to be rather general, as shown by experiments on pyrimidine and several other simple nitrogen heteroaromatic molecules.

Se describe una fotorreacción de adición de alcoholes a purinas. Los productos obtenidos por la adición de metanol, dos isómeros del etanol e isopropanol se han aislado y caracterizado mediante analisis químico, además de sus espectros de masa, UV, 1R y NMR. Fundamentalmente sobre la base de datos de NMR y usando purinas deuteradas, se ha demostrado que la adición involucra unión entre el carbono α del alcohol y el carbono‐6 del anillo de la base. El rendimiento cuántico de la reacción, a 254 nm es aproximadamente 0·2 en metanol, etanol o isopropanol deoxigenados y secos. La reacción parece ser algo general, como lo demuestran los experimentos realizados en pirimidina y algunas otras moléculas heteroaromáticas.
Primary calibration of coiled brachytherapy sources
Authors: Paxton Adam B. , Culberson Wesley S. , DeWerd Larry A. , Micka John A.
Published: January 2008

Coiled brachytherapy sources have been developed by RadioMed Corporation for use as low‐dose‐rate (LDR) interstitial implants. The coiled sources are provided in integer lengths from 1 to and address many common issues seen with traditional LDR brachytherapy sources. The current standard for determining the air‐kerma strength of low‐energy LDR brachytherapy sources is the National Institute of Standards and Technology's Wide‐Angle Free‐Air Chamber (NIST WAFAC). Due to geometric limitations, however, the NIST WAFAC is unable to determine the of sources longer than . This project utilized the University of Wisconsin's Variable‐Aperture Free‐Air Chamber (UW VAFAC) to determine the of the longer coiled sources. The UW VAFAC has shown agreement in values of length coils to within 1% of those determined with the NIST WAFAC, but the UW VAFAC does not share the same geometric limitations as the NIST WAFAC. A new source holder was constructed to hold the coiled sources in place during measurements with the UW VAFAC. Correction factors for the increased length of the sources have been determined and applied to the measurements. Using the new source holder and corrections, the of 3 and coiled sources has been determined. Corrected UW VAFAC data and ionization current measurements from well chambers have been used to determine calibration coefficients for use in the measurement of 3 and coiled sources in well chambers. Thus, the UW VAFAC has provided the first transferable, primary measurement of low‐energy LDR brachytherapy sources with lengths greater than .
Evaluation of optically stimulated luminescence (OSL) dosimeters for passive dosimetry of high‐energy photon and electron beams in radiotherapy
Authors: Yukihara E. G. , Mardirossian G. , Mirzasadeghi M. , Guduru S. , Ahmad S.
Published: January 2008

This article investigates the performance of optically stimulated luminescence dosimeters (OSLDs) for application in radiotherapy. Central‐axis depth dose curves and optically stimulated luminescence (OSL) responses were obtained in a water phantom for 6 and photons, and for 6, 9, 12, 16, and electron beams from a Varian 21EX linear accelerator. Single OSL measurements could be repeated with a precision of 0.7% (one standard deviation) and the differences between absorbed doses measured with OSLDs and an ionization chamber were within for photon beams. Similar results were obtained for electron beams in the low‐gradient region after correction for a 1.9% photon‐to‐electron bias. The distance‐to‐agreement values were of the order of for electrons in high dose gradient regions. Additional investigations also demonstrated that the OSL response dependence on dose rate, field size, and irradiation temperature is less than 1% in the conditions of the present study. Regarding the beam energy/quality dependence, the relative response of the OSLD for was of the response for the photon beam. The OSLD response for the electron beams relative to the photon beam. The OSLD response for the electron beams relative to the photon beam was in average 1.9% higher, but this result requires further confirmation. The relative response did not seem to vary with electron energy at within the experimental uncertainties (0.5% in average) and, therefore, a fixed correction factor of 1.9% eliminated the energy dependence in our experimental conditions.
Visualizing localized dynamic changes during epileptic seizure onset in vivo with diffuse optical tomography
Authors: Wang Qiang , Liang Xiaoping , Liu Zhao , Zhang Qizhi , Carney Paul , Jiang Huabei
Published: January 2008

Diffuse optical tomography (DOT) is a promising functional imaging modality due to its ability to provide quantitative and dynamic tomographic imaging of brain functions. This pilot study was conducted to demonstrate that DOT can be used to visualize the changes in local hemodynamics during seizures. The focal seizure was induced by microinjection of of antagonist bicuculline methiodide (BMI) into the left parietal neocortex of male Harlen Sprague–Dawley rats, which was imaged by a multispectral continuous‐wave DOT system. Functional images were obtained by our finite element based image reconstruction algorithm. A series of dynamic 2D images were obtained to delineate the time course of concentration changes of oxyhaemoglobin, deoxyhaemoglobin, and total hemoglobin in the rat brain during seizure onset. The BMI induced epileptic foci were localized and observed over time from the images obtained. Our results suggest that diffuse optical tomography may be a promising modality for epilepsy imaging due to its ability to localize epileptic foci as well as its potential to map the functional activity in the area of human cerebral cortex in planning of epilepsy surgery.
Adaptive mean filtering for noise reduction in CT polymer gel dosimetry
Authors: Hilts Michelle , Jirasek Andrew
Published: January 2008

X‐ray computed tomography (CT) as a method of extracting 3D dose information from irradiated polymer gel dosimeters is showing potential as a practical means to implement gel dosimetry in a radiation therapy clinic. However, the response of CT contrast to dose is weak and noise reduction is critical in order to achieve adequate dose resolutions with this method. Phantom design and CT imaging technique have both been shown to decrease image noise. In addition, image postprocessing using noise reduction filtering techniques have been proposed. This work evaluates in detail the use of the adaptive mean filter for reducing noise in CT gel dosimetry. Filter performance is systematically tested using both synthetic patterns mimicking a range of clinical dose distribution features as well as actual clinical dose distributions. Both low and high signal‐to‐noise ratio (SNR) situations are examined. For all cases, the effects of filter kernel size and the number of iterations are investigated. Results indicate that adaptive mean filtering is a highly effective tool for noise reduction CT gel dosimetry. The optimum filtering strategy depends on characteristics of the dose distributions and image noise level. For low noise images (SNR ), the filtered results are excellent and use of adaptive mean filtering is recommended as a standard processing tool. For high noise images (SNR ) adaptive mean filtering can also produce excellent results, but filtering must be approached with more caution as spatial and dose distortions of the original dose distribution can occur.
Physiological Sex Predicts Hybrid Sterility Regardless of Genotype
Authors: Malone John H. , Michalak P.
Published: January 2008

Reproductive isolation between biological species is characterized by Haldane's rule, which states that the heterogametic sex (XY or ZW) suffers the most dysfunctional effects of hybridization. It has been hypothesized that, in addition to X-linked recessive genes, Haldane's rule also reflects the faster evolution of genes related to male reproduction (faster-male evolution). We used sex-reversed hybrid
Xenopus
to test faster-male evolution by examining the fertility of sex-reversed individuals with the genotype of the inverse phenotypic sex. Hybrid males are sterile and hybrid females are fertile irrespective of their genotypic sex. Gene expression profiles match these adult phenotypes, and our results demonstrate that faster-male evolution is the most likely mechanism producing hybrid male sterility.
Commentary — The Proteomics: A New Tool for Chinese Medicine Research
Authors: Li Shi-Sheng
Published: January 2008

Proteomics technology is based on the vast analytical power for protein/peptide identification and quantification offered by modern mass spectrometry coupled with hyphenated separation techniques such as two-dimensional gel electrophoresis (2DE) and micro- or nano-scale multidimensional liquid chromatography. The rapid growth of proteomics field provides an array of new tools for the integration of traditional Chinese medicine (TCM) with modern technology and systems biology, and is potentially advancing the progress of modernization and internationalization of TCM. Cho, in this issue of the American Journal of Chinese Medicine, highlights the recent application of 2DE-based and bottom-up proteomics in Chinese medicine research, including the exploration of pharmacological mechanisms of the actions of TCM, the facilitation of herb authentication and identification, and the profiling of protein expression following acupuncture treatment in animal models. Recent development in proteomics has provided further refinement on the analysis of proteins posttranslational modifications as well as quantitative comparison of different proteomes, and enabled the study of proteomes of specific diseases or biological processes under clinically relevant conditions. It is conceivable that the application of technologies developed in proteomics, genomics and metabonomics in the clinical practice and basic research of Chinese medicine will eventually lead to the reconciliation and integration of TCM and contemporary medicine. Chinese medicine is fundamentally a highly personalized medicine; perhaps it is time to embrace the arrival of TCM OMICS era in Chinese medicine research.
fMRI Study of Pain Reaction in the Brain under State of "Qigong"
Authors: Yu Wei-Lin , Li Xiao-Qing , Tang Wei-Jun , Li Yuan , Weng Xu-Chu , Chen Yi-Zhang
Published: January 2008

In this study, 4 male Qigong masters (aged 60 ± 12) who had Qigong practicing experience for more than 30 years were tested. By using the technique of fMRI, the change of brain function under the state of Qigong was observed through the peripheral pain stimulation generated by potassium penetrating method. The fMRI examination was running on a GE signa VH/3.0 T MRI machine and block design was used. The test was repeated several times, which was carried out before and 15 min after Qigong practicing. The heart and respiration rate of these 4 Qigong masters were monitored during the whole test. SPM2 was used for the data analysis, and the result showed that before Qigong practicing, besides SI and SII-insula regions, many other Brodmann areas, the cigulate cortex, the thalamus, and the cerebellum were all activated, while 15 min after that, the activated areas were decreased obviously, which were mainly at the SII-insula region and some other Brodmann areas. Since the SII-insula region was activated in both of these two states, further analysis of the response curve was focused on it. Its response amplitude under the state of Qigong (3.5%) was greater than that before Qigong (1.2%). Our result indicated that the main manifestation of brain functional change under Qigong was functional suppressing, but in some particular regions such as SII-insula region in our study, the response amplitude was increased. Further study of the exact physiological mechanism of Qigong is needed.
SerumIgG,IgA,IgM, andIgELevels after Electroacupuncture and Diet Therapy in Obese Women
Authors: Cabioglu Mehmet T. , Ergene Neyhan , Surucu H. Selcuk , Çelik H. Hamdi , Findik Duygu
Published: January 2008

We investigated the effect of acupuncture therapy on obese women's body weight and peripheral blood levels of serum immunoglobulin G ( IgG ), immunoglobulin A ( IgA ), immunoglobulin M ( IgM ), and immunoglobulin E ( IgE ). Sixty-three healthy women were assigned into 3 groups: placebo electroacupuncture ( n = 13; mean age, 40.5 ± 4.2 years; body mass index [BMI], 33.5 ± 4.2), diet restriction ( n = 23; mean age, 42.9 ± 4.0 years; BMI, 34.6 ± 2.9), and electroacupuncture ( n = 24; mean age, 40.1 ± 5.9 years; BMI, 33.9 ± 2.7). Electroacupuncture was applied to the Hunger and Shen Men ear points and to the LI 4, LI 11, St 36, St 44, and Ren 6 body points for 30 min once daily for 20 days. A restricted diet of 1400 kilocalories was given to participants in all 3 groups for 20 days. Weight was lost significantly in subjects in the electroacupuncture group compared to those in the diet restriction and placebo electroacupuncture groups ( p < 0.000, Tukey test). Modulations in serum IgG ( p < 0.001) were apparent in women treated with electroacupuncture compared with women treated with placebo electroacupuncture and restricted diet only. No significant changes were seen in serum IgA , IgM , and IgE levels among the 3 groups. Our results suggest that electroacupuncture can be effectively used to treat obesity. We also observed a modulating effect of serum IgG , which is associated with weight loss, in patients in the electroacupuncture group.
Consumers, participants, and creators
Authors: Svoen Brit
Published: January 2008

With the ever-changing and ubiquitous media environment as a backdrop, this article analyzes how young people respond to television and new media and how media is used in their everyday lives, in their social relations, and in building an identity. The analysis is based on findings from a user study of 10 to15 year-olds in Norway. The respondents were recruited among active Internet users, and since they were early adopters of new technology, they can be considered a vanguard. Starting with a broad outline of some essential earlier studies on young people's use of media in Europe and in the United States, the results of this study are presented and ideas for further development are discussed. Media, and in particular visual and social media, play an increasingly important role in young people's lives. But a shift is about to happen in their relationship to the media; from being an audience and users to becoming participants and creators as well. This article is a contribution to the previous rather poor research on these ongoing changes.