First Observation (first + observation)

Distribution by Scientific Domains
Distribution within Medical Sciences


Selected Abstracts


ChemInform Abstract: First Observation of Electronic Conductivity in Mixed-Valence Tellurium Oxides.

CHEMINFORM, Issue 11 2010
Theeranun Siritanon
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]


Alkylations of N4 -(4-Pyridyl)-3,5-di(2-pyridyl)-1,2,4-triazole: First Observation of Room-Temperature Rearrangement of an N4 -Substituted Triazole to the N1 Analogue

CHEMISTRY - AN ASIAN JOURNAL, Issue 4 2010
Jonathan
Abstract Attempts to use alkylation to introduce a positive charge at the nitrogen atom of the 4-pyridyl ring in the bis(bidentate) triazole ligand N4 -(4-pyridyl)-3,5-di(2-pyridyl)-1,2,4-triazole (pydpt) were made to ascertain what effect a strongly electron-withdrawing group would have on the magnetic properties of any subsequent iron(II) complexes. Alkylation of pydpt under relatively mild conditions led in some cases to unexpected rearrangement products. Specifically, when benzyl bromide is used as the alkylating agent, and the reaction is carried out in refluxing acetonitrile, the N4 substituent moves to the N1,position. However, when the same reaction is performed in dichloromethane at room temperature, the rearrangement does not occur and the desired product containing an alkylated N4 substituent is obtained. Heating a pure sample of N4 -Bzpydpt,Br to reflux in MeCN resulted in clean conversion to N1 -Bzpydpt,Br. This is consistent with N4 -Bzpydpt,Br being the kinetic product whereas N1 -Bzpydpt,Br is the thermodynamic product. When methyl iodide is used as the alkylating agent, the N4 to N1 rearrangement occurs even at room temperature, and at reflux pydpt is doubly alkylated. The observation of the lowest reported temperatures for an N4 to N1 rearrangement is due to this particular rearrangement involving nucleophilic aromatic substitution: a possible mechanism for this transformation is suggested. [source]


First observation of natural circular dichroism spectra in the extreme ultraviolet region using a polarizing undulator-based optical system and its polarization characteristics

JOURNAL OF SYNCHROTRON RADIATION, Issue 4 2009
Masahito Tanaka
Natural circular dichroism (CD) spectra in the extreme ultraviolet (EUV) region down to a wavelength of 80,nm have been observed for the first time, using an alanine thin film deposited on sodium salicylate coated glass as a sample. Calibrated EUV-CD spectra of l -alanine exhibited a large negative peak at around 120,nm and a positive CD signal below 90,nm, which were roughly predicted by theoretical calculations. A CD measurement system with an Onuki-type polarizing undulator was used to obtain the EUV-CD spectra. This CD system, the development of which took five years, can be used to observe even weak natural CD spectra. The polarization characteristics of this system were also evaluated in order to calibrate the recorded CD spectra. [source]


First observation of homozygous hemoglobin hamadan (B 56 (D7) GLY-ARG) and beta thalassemia (-29 G>A)- hemoglobin Hamadan combination in a Turkish family

AMERICAN JOURNAL OF HEMATOLOGY, Issue 4 2003
Ece Akar
Abstract During screening surveys for beta thalassemia and abnormal hemoglobins in Mugla, a city located in the Aegean Region of Turkey, a hemoglobin variant was detected in two large families residing in two neigboring cities (i.e., Mu,la and Aydin) without any clinical signs. Further analysis of the variant revealed it as Hb Hamadan (B 56 (D7) GLY-ARG). Family screening revealed the father of the propositus as homozygote Hb Hamadan. The grandfather of the index case was detected as combination of Hb Hamadan with beta thalassemia. The beta thalassemia carrier had a promotor mutation at ,29 G>A, which is also a novel mutation. Furthermore, we described a simple and rapid restriction enzyme digestion protocol (Hha I) for the verification of Hb Hamadan. The clinical and hematologic data of the index case and his father showed that neither homozygous Hb Hamadan nor combination with beta thalassemia has clinical importance. This is also important especially from the prenatal diagnosis point of view. Am. J. Hematol. 74:280,282, 2003. © 2003 Wiley-Liss, Inc. [source]


The CAG repeat polymorphism within the androgen receptor gene and maleness,

INTERNATIONAL JOURNAL OF ANDROLOGY, Issue 2 2003
Michael Zitzmann
Summary The androgen testosterone and its metabolite dihydrotestosterone exert their effects on gene expression and thus effect maleness via the androgen receptor (AR). A diverse range of clinical conditions starting with complete androgen insensitivity has been correlated with mutations in the AR. Subtle modulations of the transcriptional activity induced by the AR have also been observed and frequently assigned to a polyglutamine stretch of variable length within the N-terminal domain of the receptor. This stretch is encoded by a variable number of CAG triplets in exon 1 of the AR gene located on the X chromosome. First observations of pathologically elongated AR CAG repeats in patients with X-linked spino-bulbar muscular atrophy showing marked hypoandrogenic traits were supplemented by partially conflicting findings of statistical significance also within the normal range of CAG repeat length: an involvement of prostate tissue, spermatogenesis, bone density, hair growth, cardiovascular risk factors and psychological factors has been demonstrated. The highly polymorphic nature of glutamine residues within the AR protein implies a subtle gradation of androgenicity among individuals within an environment of normal testosterone levels providing relevant ligand binding to ARs. This modulation of androgen effects may be small but continuously present during a man's lifetime and, hence, exerts effects that are measurable in many tissues as various degrees of androgenicity and represents a relevant effector of maleness. It remains to be elucidated whether these insights are important enough to become part of individually useful laboratory assessments. [source]


Co-inheritance of Hb Hershey [,70(E14) Ala,Gly] and Hb La Pommeraie [,133(H11)Val,Met] in a Sicilian subject

EUROPEAN JOURNAL OF HAEMATOLOGY, Issue 5 2010
Antonino Giambona
Abstract Objectives:,This report represents the first observation in Sicily of two rare , -globin gene variants, Hb Hershey [,70(E14) Ala,Gly] and Hb La Pommeraie [,133(H11)Val,Met], found in a 35-year-old male patient from Messina, in the north-east of Sicily during population screening for hemoglobinopathies. Methods: The occurrence of the Hb variants was assessed by cation exchange chromatography while complete blood counts were obtained using automatic cell counters. Red cell lysates were analyzed by electrophoresis at alkaline and acid pH. Stability of hemoglobin was checked by the isopropanol precipitation test and by the heat tests while inclusion bodies and reticulocyte count were determined by incubation of blood samples with brilliant cresyl blue. Molecular analysis was performed by DNA sequencing of ,- and , -globin genes. Results: We observed an abnormally high performance liquid chromatography elution with a slight reduction in mean corpuscular volume and mean corpuscular haemoglobin parameters and mutations at codon 70 GCC,GGC (Hb Hershey) and at codon 133 GTG,ATG (Hb La Pommeraie) in , -globin gene. Conclusion: Family analysis of three generations demonstrated the presence of these two mutations in trans. So it was possible to describe the phenotypes of these variants in a heterozygous state and in double heterozygous state. [source]


Synthesis and Functionalization of Germanium Triphenylcorrolate: The First Example of a Partially Brominated Corrole

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 16 2007
Sara Nardis
Abstract Ge complexes of 5,10,15-triphenylcorrole were prepared in refluxing dry DMF using GeCl4 as the source of Ge. Chromatographic separation of the crude reaction mixture afforded the ,-oxo dimer 1 and the methoxy derivative 2a. The corresponding chloride 2b can be obtained by treatment of 1 or 2a with HCl. The reaction of 2a with Br2 in CHCl3/py afforded the hexabromo derivative 3 as the main product, giving the first indication of the regioselective substitution of pyrroles B and C on the corrole ring. The fully brominated open-chain tetrapyrrole 4 was also characterized as a reaction by-product. Different partially brominated Ge complexes 5 and 6 have been obtained by variation of reaction conditions, while the heptabromo derivative was obtained in a mixture with the corresponding fully brominated Gecorrole. Photophysical characterization of Ge corrolates confirmed the high fluorescence quantum yield of such complexes, and also led to the first observation of phosphorescence emissions from corrole complexes. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]


Unusual cone and rod properties in subterranean African mole-rats (Rodentia, Bathyergidae)

EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2004
Leo Peichl
Abstract We have determined the presence of spectral cone types, and the population densities of cones and rods, in subterranean mole-rats of the rodent family Bathyergidae, for which light and vision seems of little importance. Most mammals have two spectral cone types, a majority of middle- to long-wave-sensitive (L-) cones, and a minority of short-wave-sensitive (S-)cones. We were interested to see whether the subterranean bathyergids show the same pattern. In three species, Ansell's mole-rat Cryptomys anselli, the giant mole-rat Cryptomys mechowi and the naked mole-rat Heterocephalus glaber, spectral cone types and rods were assessed immunocytochemically with opsin-specific antibodies. All three species had rod-dominated retinae but possessed significant cone populations. A quantitative assessment in C. anselli and C. mechowi revealed surprisingly low photoreceptor densities of 100 000,150 000/mm2, and high cone proportions, , 10% (8000,15 000/mm2). In all three species, the vast majority of the cones were strongly S-opsin-immunoreactive; L-opsin immunoreactivity was much fainter. In C. anselli, , 20% of the cones showed exclusive S-opsin label, , 10% exclusive L-opsin label and , 70% strong S-opsin and faint L-opsin double label (potential dual-pigment cones). This is the first observation in any mammal of an S-opsin dominance and low levels of L-opsin across the entire retina. It contrasts starkly with the situation in the muroid blind mole-rat Spalax ehrenbergi, which has been reported to possess L-opsin but no S-opsin. Evidently, within rodents an adaptation to subterranean life is compatible with very different spectral cone properties. [source]


Isolation, characterization, sequencing and crystal structure of charybdin, a type 1 ribosome-inactivating protein from Charybdis maritima agg.

FEBS JOURNAL, Issue 12 2006
Eleftherios Touloupakis
A novel, type 1 ribosome-inactivating protein designated charybdin was isolated from bulbs of Charybdis maritima agg. The protein, consisting of a single polypeptide chain with a molecular mass of 29 kDa, inhibited translation in rabbit reticulocytes with an IC50 of 27.2 nm. Plant genomic DNA extracted from the bulb was amplified by PCR between primers based on the N-terminal and C-terminal sequence of the protein from dissolved crystals. The complete mature protein sequence was derived by partial DNA sequencing and terminal protein sequencing, and was confirmed by high-resolution crystal structure analysis. The protein contains Val at position 79 instead of the conserved Tyr residue of the ribosome-inactivating proteins known to date. To our knowledge, this is the first observation of a natural substitution of a catalytic residue at the active site of a natural ribosome-inactivating protein. This substitution in the active site may be responsible for the relatively low in vitro translation inhibitory effect compared with other ribosome-inactivating proteins. Single crystals were grown in the cold room from PEG6000 solutions. Diffraction data collected to 1.6 Å resolution were used to determine the protein structure by the molecular replacement method. The fold of the protein comprises two structural domains: an ,,+ , N-terminal domain (residues 4,190) and a mainly ,-helical C-terminal domain (residues 191,257). The active site is located in the interface between the two domains and comprises residues Val79, Tyr117, Glu167 and Arg170. [source]


Chaperone activity of recombinant maize chloroplast protein synthesis elongation factor, EF-Tu

FEBS JOURNAL, Issue 18 2004
Damodara Rao
The protein synthesis elongation factor, EF-Tu, is a protein that carries aminoacyl-tRNA to the A-site of the ribosome during the elongation phase of protein synthesis. In maize (Zea mays L) this protein has been implicated in heat tolerance, and it has been hypothesized that EF-Tu confers heat tolerance by acting as a molecular chaperone and protecting heat-labile proteins from thermal aggregation and inactivation. In this study we investigated the effect of the recombinant precursor of maize EF-Tu (pre-EF-Tu) on thermal aggregation and inactivation of the heat-labile proteins, citrate synthase and malate dehydrogenase. The recombinant pre-EF-Tu was purified from Escherichia coli expressing this protein, and mass spectrometry confirmed that the isolated protein was indeed maize EF-Tu. The purified protein was capable of binding GDP (indicative of protein activity) and was stable at 45 °C, the highest temperature used in this study to test this protein for possible chaperone activity. Importantly, the recombinant maize pre-EF-Tu displayed chaperone activity. It protected citrate synthase and malate dehydrogenase from thermal aggregation and inactivation. To our knowledge, this is the first observation of chaperone activity by a plant/eukaryotic pre-EF-Tu protein. The results of this study support the hypothesis that maize EF-Tu plays a role in heat tolerance by acting as a molecular chaperone and protecting chloroplast proteins from thermal aggregation and inactivation. [source]


A novel type of carbohydrate,protein linkage region in the tyrosine-bound S-layer glycan of Thermoanaerobacterium thermosaccharolyticum D120-70

FEBS JOURNAL, Issue 17 2000
Christina Schäffer
The surface-layer (S-layer) protein of Thermoanaerobacterium thermosaccharolyticum D120-70 contains glycosidically linked glycan chains with the repeating unit structure ,4)[,- d -Galp -(1,2)]-,- l -Rhap -(1,3)[,- d -Glcp -(1,6)]-,- d -Manp -(1,4)-,- l -Rhap -(1,3)-,- d -Glcp -(1,. After proteolytic degradation of the S-layer glycoprotein, three glycopeptide pools were isolated, which were analyzed for their carbohydrate and amino-acid compositions. In all three pools, tyrosine was identified as the amino-acid constituent, and the carbohydrate compositions corresponded to the above structure. Native polysaccharide PAGE showed the specific heterogeneity of each pool. For examination of the carbohydrate,protein linkage region, the S-layer glycan chain was partially hydrolyzed with trifluoroacetic acid. 1D and 2D NMR spectroscopy, including a novel diffusion-edited difference experiment, showed the O-glycosidic linkage region ,- d -glucopyranose,O -tyrosine. No evidence was found of additional sugars originating from a putative core region between the glycan repeating units and the S-layer polypeptide. For the determination of chain-length variability in the S-layer glycan, the different glycopeptide pools were investigated by matrix-assisted laser desorption ionization-time of flight mass spectrometry, revealing that the degree of polymerization of the S-layer glycan repeats varied between three and 10. All masses were assigned to multiples of the repeating units plus the peptide portion. This result implies that no core structure is present and thus supports the data from the NMR spectroscopy analyses. This is the first observation of a bacterial S-layer glycan without a core region connecting the carbohydrate moiety with the polypeptide portion. [source]


Long-term efficacy and safety of adefovir dipivoxil for the treatment of hepatitis B e antigen,positive chronic hepatitis B,

HEPATOLOGY, Issue 3 2008
Patrick Marcellin
Treatment of 171 patients with hepatitis B e antigen (HBeAg)-positive chronic hepatitis B (CHB) with adefovir dipivoxil (ADV) 10 mg over 48 weeks resulted in significant histological, virological, serological, and biochemical improvement compared with placebo. The long-term efficacy and safety of ADV in a subset of these patients was investigated for up to 5 years. Sixty-five patients given ADV 10 mg in year 1 elected to continue in a long-term safety and efficacy study (LTSES). At enrollment, the 65 LTSES patients were a median 34 years old, 83% male, 74% Asian, 23% Caucasian, median baseline serum hepatitis B virus (HBV) DNA 8.45 log10 copies/mL, and median baseline alanine aminotransferase (ALT) 2.0 × upper limit of normal. At 5 years on study, the median changes from baseline in serum HBV DNA and ALT for the 41 patients still on ADV were 4.05 log10 copies/mL and ,50 U/L, respectively. HBeAg loss and seroconversion were observed in 58% and 48% of patients by end of study, respectively. Fifteen patients had baseline and end of follow-up liver biopsies; improvements in necroinflammation and fibrosis were seen in 67% and 60% of these patients, respectively. Adefovir resistance mutations A181V or N236T developed in 13 LTSES patients; the first observation was at study week 195. There were no serious adverse events related to ADV. Conclusion: Treatment with ADV beyond 48 weeks was well tolerated and produced long-term virological, biochemical, serological, and histological improvement. (HEPATOLOGY 2008;48:750,758.) [source]


Polymer,Clay Nanocomposites Exhibiting Abnormal Necking Phenomena Accompanied by Extremely Large Reversible Elongations and Excellent Transparency,

ADVANCED MATERIALS, Issue 17 2006
K. Haraguchi
Soft and transparent polymer,clay nanocomposites (see figure), consisting of hydrophobic poly(2-methoxyethylacrylate) and hydrophilic inorganic clay, with a unique clay-network morphology have been synthesized by in,situ free-radical polymerization. The nanocomposites exhibit the first observation of abnormal necking behavior accompanied by extremely large reversible elongation (1000,3000,%) and excellent optical transparency, regardless of the clay content (1,30,wt,%). [source]


Schnitzler syndrome: response to anakinra in two cases and a review of the literature

INTERNATIONAL JOURNAL OF DERMATOLOGY, Issue 11 2009
Christian Schuster MD
Background, Schnitzler syndrome is a rare disease characterized by a chronic urticarial eruption and monoclonal gammopathy, as well as clinical and laboratory signs of inflammation. The pathophysiology is still unknown, although various autoantibody-mediated mechanisms have been described. Complete remission of symptoms has been reported recently in patients with Schnitzler syndrome treated with anakinra, an interleukin-1 receptor antagonist. Methods, Two patients with Schnitzler syndrome treated with anakinra therapy are presented. Results, We report two cases of nearly complete remission of symptoms in Schnitzler syndrome after the initiation of anakinra therapy, and the first observation of a relapse under continuous daily anakinra therapy. A review of the published literature on the treatment of Schnitzler syndrome with anakinra is presented. Conclusions, Based on published data, monotherapy with anakinra is currently the most promising treatment for Schnitzler syndrome, because it is able to induce complete remission of symptoms. [source]


Larval development in the Homoscleromorpha (Porifera, Demospongiae)

INVERTEBRATE BIOLOGY, Issue 3 2003
Nicole Boury-Esnault
Abstract. Embryonic development from coeloblastula to fully developed larva was investigated in 8 Mediterranean homoscleromorph species: Oscarella lobularis, O. tuberculata, O. microlobata, O. imperialis, Plakina trilopha, P. jani, Corticium candelabrum, and Pseudocorticium jarrei. Morphogenesis of the larva is similar in all these species; however, cell proliferation is more active in species of Oscarella than in Plakina and C. candelabrum. The result of cell division is a wrinkled, flagellated larva, called a cinctoblastula. It is composed of a columnar epithelium of polarized, monoflagellated cells among which are scattered a few non-flagellated ovoid cells. The central cavity always contains symbiotic bacteria. Maternal cells are also present in O. lobularis, O. imperialis, and P. jarrei. In the fully developed larva, cell shape and dimensions are constant for each species. The cells of the anterior pole have large vacuoles with heterogeneous material; those of the postero-lateral zone have an intranuclear paracrystalline inclusion; and the flagellated cells of the posterior pole have large osmiophilic inclusions. Intercellular junctions join the apical parts of the cells, beneath which are other specialized cell junctions. A basement membrane underlying the flagellated cells lines the larval cavity. This is the first observation of a basement membrane in a poriferan larva. The basal apparatus of flagellated cells is characterized by an accessory centriole located exactly beneath the basal body. The single basal rootlet is cross striated. The presence of a basement membrane and a true epithelium in the larva of Homoscleromorpha,unique among poriferan clades and shared with Eumetazoa,suggests that Demospongiae could be paraphyletic. [source]


Abstracts of the 8th Meeting of the Italian Peripheral Nerve Study Group: 83

JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 1 2003
G Lauria
We describe a 64-year-old patient complaining of progressive gait disturbance, referred to the compressive effect of multiple discal protrusions, for about 3 years. At the age of 62 he presented epileptic seizures during a febrile episode. Cerebral MRI showed bilateral frontobasal T2-weighted hyperintensity involving cortex and white matter. Partial seizures reappeared one year later and a MRI revealed a mild frontobasal atrophy. At the moment of our observation, neurological examination showed waddling gait with bilateral foot drop, muscular atrophy and weakness limited to the gluteal muscles and widespread deep tendon areflexia. Nerve conduction studies showed absent F-waves at both upper and lower limb examination, with normal distal sensorimotor nerve conduction. Needle EMG examination detected mild chronic partial denervation, predominant in proximal muscles of lower limbs. Somatosensory evoked potentials recorded from upper extremities showed bilateral increase in early latencies (N9). Overall, neurophysiological findings indicated a widespread radiculopathy. Serum exams revealed positive anti-nucleus (1:640, granular). CSF examination detected increased IgG level and several oligoclonal bands. Chest radiogram was normal. Soon after our first observation, the patient showed symptoms of respiratory insufficiency. A CT scans revealed a thoracic mass compatible with microcytoma, whereas anti-Hu (3 +) antibodies and increased NSE (neuronal specific enolase) titer were found. In the following two weeks, the patient showed a progressive worsening of the general clinical conditions and died. We interpreted this complex neurological picture, which included an atypical limbic encephalitis and a slowly progressive polyradiculopathy, as a paraneoplastic syndrome. The almost complete resolution of the encephalitic process and the subtle chronic involvement of the peripheral nervous system, characterized by a limited, though widespread, radicular impairment, are rather peculiar features. [source]


Cooperative scattering of light and atoms in ultracold atomic gases

LASER PHYSICS LETTERS, Issue 7 2008
H. Uys
Abstract Superradiance and coherent atomic recoil lasing are two closely related phenomena, both resulting from the cooperative scattering of light by atoms. In ultracold atomic gases below the critical temperature for Bose-Einstein condensation these processes take place with the simultaneous amplification of the atomic matter waves. We explore these phenomena by surveying some of the experimental and theoretical developments that have emerged in this field of study since the first observation of superradiant scattering from a Bose-Einstein condensate in 1999 [1]. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]


Wide-band Raman Stokes and anti-Stokes comb lasing in a BaF2 single crystal under picosecond pumping

LASER PHYSICS LETTERS, Issue 4 2008
A.A. Kaminskii
Abstract We report on the first observation of stimulated Raman scattering (SRS) in a crystal of cubic BaF2. All registered Stokes and anti-Stokes lasing sidebands in the visible and near-IR (up to the 41st order) are identified to the single ,(3) -promoting vibration mode (,SRS , 238 cm,1) of the crystal. The recorded very broad nonlinear lasing comb (more than one octave spanning) in BaF2 opens the possibility for experiments on femtosecond waveform synthesis and other laser comb applications. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]


Low magnetic fields behavior of photon echo in LuLiF4:Er3+

LASER PHYSICS LETTERS, Issue 9 2006
V. N. Lisin
Abstract It is reported about the first observation and studying of the photon echo in LuLiF4:Er3+. The energy transition is 4I15/2 , 4F9/2 (, = 6536 Å). The density of ErF3 is 0.025 wt%. The operation temperature is 1.9 K. Measurements were spent at low (up to 1200 Oe) and even zero external magnetic fields. It was studied a behavior of the photon echo intensity versus the magnetic field magnitude and direction about the crystal axis C and versus the laser pulse separation t12. It was observed an exponential growth and then, after some plateau, an exponential decreasing of the photon echo intensity as a function of magnetic field with increasing of the magnetic field from zero value. The parameters describing the exponential growth and decreasing are not depended on direction of magnetic field. Value of a magnetic field at which the echo intensity accepts the maximum, and quantity of this maximum decrease with increased the pulse separation t12 and the angle , between the magnetic field and crystal axis. The echo intensity exponentially decreases with increased , . The parameter describing the exponential decreasing is not depended on the magnitude of the field. The echo intensity as a function of pulse separation shows exponential decay. The phase relaxation time is depended on the magnitude and direction of the magnetic field. T2 is equal to 202 ± 16 ns at zero magnetic field. Phenomenological formula is suggested, which qualitatively presents the mentioned dependencies. Polarization properties of the backward photon echo in this crystal are studied also. (© 2006 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source]


Polymer Chain Collapse in Supercritical Fluids.

MACROMOLECULAR SYMPOSIA, Issue 1 2009

Abstract A few years ago we reported the first observation, by computer simulations, of polymer chain collapse near the lower critical solution temperature (LCST).1 In the present work, we extended the above study to understand the underlying physics of a single polymer chain collapse near LCST and its relationship to phase boundaries in the T-x plane. Effects of solvent and monomer sizes, and solvent and monomer energetic interactions are studied. Using Monte Carlo simulations, the mean end-to-end distance (R) and gyration radius (Rg) are calculated for a single chain in a supercritical fluid solvent over a broad range of densities, pressures and temperatures. In general, the chain collapses as temperature increases at constant pressure. Upon a further temperature increase, the chain expands again to approach the athermal limit provided that the temperature is sufficiently high. The collapse is related to an LCST phase boundary while the expansion represents the signature of an upper-critical solution temperature (UCST) suggesting the existence of a closed-immiscibility loop. By manipulating the strength of the energetic interactions as well as the solvent-to-monomer size ratio, the size of the size of the immiscibility loop can be fine-tuned. The relationship among size and the segment-solvent energetic interaction are correlated by a conformational parameter (,) for the first time. By monitoring the , behavior, it is possible to predict solution's phase behavior, transition zone from LCST-UCST in a closed-loop miscibility behavior. The above relationship between chain conformation to phase boundaries may be useful in understanding phase stability in compressible polymer-solvent mixtures. [source]


The Natural History of Sensitizations to Food and Aeroallergens in Atopic Dermatitis: A 4-Year Follow-Up

PEDIATRIC DERMATOLOGY, Issue 4 2000
Annalisa Patrizi M.D.
Generally the dermatitis disappears during the first years of life, but it is often followed by the appearance of allergic respiratory diseases (ARDs). Our aim was to establish the risk factors for developing an ARD in children with AD. We followed up for 4 years 78 children (51 boys, 27 girls) with mild (26%), moderate (48%), and severe (26%) AD (clinical score proposed by Rajka and Langeland). In all the patients IgE serum levels were checked and skin prick tests (SPTs) were performed at the first examination. The SPTs were repeated in 68 children at the end of the study. The children with severe AD had significantly higher IgE serum levels than those with mild or moderate AD. SPTs at the first observation were positive in 47% of cases, mostly in patients with severe AD, with a prevalence of food allergens, particularly in younger patients. At the second observation, SPTs were positive in 65% of cases, including 100% of children with severe AD. Inhalants were the most common allergens. An ARD appeared in 38% of all patients: in 75% of those with severe AD and in 54% of those with a positive first SPT. Allergic screening should be carried out at an early age, especially in severe AD, since SPT positivity to food allergens, associated with severe clinical AD symptoms and a high IgE serum level, identifies those children ages 0,3 years at high risk of development of ARD. [source]


Linkage of genes for sodium channel and cytochrome P450 (CYP6B10) in Heliothis virescens

PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 2 2002
Sujin Park
Abstract Genetic linkage of hscp (heliothis sodium channel protein) and CYP6B10 was discovered in Heliothis virescens. The hscp gene encodes the sodium channel target of pyrethroid insecticides and cytochrome P450 genes encode important enzymes involved in detoxication of various pesticides. Previously, two mechanisms, nerve insensitivity due to sodium channel and synergism by propynyl aryl ethers, were observed in pyrethroid-resistant H virescens and were not separated by repeated back-crossing. We hypothesized genetic linkage of target site insensitivity and monooxygenase-mediated detoxication. Single nucleotide polymorphisms were discovered in IIS6 of hscp; Hpy of hscp and CYP6B10. Segregation of these and other markers was tested in backcrosses. We observed co-segregation of hscp to CYP6B10, but both genes assorted independently of y, ye and sex. Genes y and ye assorted independently of each other. This was the first observation of linkage between genes controlling detoxication and sodium ion channel insensitivity in a species known to express high levels of pyrethroid resistance. Linkage was not likely because this species has 31 chromosomes; therefore, we will investigate the possibility of a resistance cassette. We expect similar linkage in other noctuid pests. © 2001 Society of Chemical Industry [source]


Sub-5-fs Real-time Spectroscopy of Transition States in Bacteriorhodopsin During Retinal Isomerization,

PHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 2 2007
Takayoshi Kobayashi
By using a sub-5-fs visible laser pulse, we have made the first observation of the vibrational spectra of the transition state during trans-cis isomerization in the retinal chromophore of bacteriorhodopsin (bRS68). No instant isomerization of the retinal occurs in spite of electron promotion from the bonding ,-orbital to the anti-bonding ,*-orbital. The difference between the in-plane and out-of-plane vibrational frequencies (about 1150,1250 and 900,1000 cm,1, respectively) is reduced during the first time period. The vibrational spectra after this period became very broad and weak and are ascribed to a "silent state." The silent state lasts for 700,900 fs until the chromophore isomerizes to the cis -C13=C14 conformation. The frequency of the C=C stretching mode was modulated by the torsion mode of the C13=C14 double bond with a period of 200 fs. The modulation was clearly observed for four to five periods. Using the empirical equation for the relation between bond length and stretching frequency, we determined the transitional C=C bond length with about 0.01 Å accuracy during the torsion motion around the double bond with 1-fs time resolution. [source]


Splitting of X-ray photoelectron spectra in incommensurate ferroelectric TlInS2 crystals

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2003
J. Grigas
Abstract This paper presents the first observation of the resolved splitting of X-ray photoelectron spectra (XPS) in the incommensurate phase of the ferroelectric semiconductor TlInS2 single crystal. The XPS were measured with monochromatised Al K, radiation in the energy range 0,1400 eV and the temperature range 195,300 K. At room temperature, the valence band is located 1,9 eV below the Fermi level. The chemical shifts in the TlInS2 crystal for the Tl, In and S states are obtained. The mechanism of the XPS splitting in the incommensurate phase is discussed. [source]


Stress-related RNase PR-10c is post-translationally modified by glutathione in birch

PLANT CELL & ENVIRONMENT, Issue 6 2002
K. M. Koistinen
Abstract The PR-10c (previously termed as Bet v 1-Sc3) protein of birch belongs to the family of intracellular pathogenesis-related proteins. The high-performance liquid chromatography electrospray ionization ion trap mass spectrometry (HPLC-ESI-MS) analysis of PR-10c-His fusion protein, produced in Escherichia coli, revealed three major peaks and masses. Enzymatic digestions and HPLC-ESI-MS and matrix assisted laser desorption/ionization , time of flight mass spectrometry (MALDI-TOF-MS) analyses of each fraction indicated that PR-10c-His protein is post-translationally modified by carbamylation and S-glutathiolation. Carbamylation was localized into the N-terminal end of PR-10c-His and does not represent a biologically significant modification. The possible nuclease activity of PR-10c was analysed with S-glutathiolated and reduced fractions of PR-10c-His fusion protein. Both forms of PR-10c-His as well as the dimeric form of the protein possess RNase activity which is capable of digesting different RNA substrates. None of the fractions showed activity against single- or double-stranded DNA. The MALDI-TOF-MS analysis of PR-10c polypeptide extracted from zinc-exposed birch roots showed that the protein is post-translationally modified by glutathione (, -Glu-Cys-Gly) also in vivo. The S-glutathiolated cysteine residue of PR-10c is not conserved among Bet v 1 homologous proteins and is also unique in the PR-10 family. As far as we know this is the first observation of S-glutathiolation in plants, or any post-translational modification in the PR-10 family of proteins. [source]


Update on the clinical features and natural history of Wolf,Hirschhorn (4p-) syndrome: Experience with 87 patients and recommendations for routine health supervision,

AMERICAN JOURNAL OF MEDICAL GENETICS, Issue 4 2008
Agatino Battaglia
Abstract Wolf,Hirschhorn syndrome (WHS) is a well-known multiple congenital anomalies/mental retardation syndrome, firstly described in 1961 by Cooper and Hirschhorn. Its frequency is estimated as 1/50,000,1/20,000 births, with a female predilection of 2:1. The disorder is caused by partial loss of material from the distal portion of the short arm of chromosome 4 (4p16.3), and is considered a contiguous gene syndrome. No single gene deletions or intragenic mutations have been shown to confer the full WHS phenotype. Since the disorder was brought to the attention of geneticists, many additional cases have been published. Only in 1999, however, were the first data on the natural history brought to the attention of the medical community. The purpose of the present study is to help delineate in more detail and over a longer period of time, the natural history of WHS, in order to establish appropriate health supervision and anticipatory guidance for individuals with this disorder. We have collected information on 87 patients diagnosed with WHS (54 females and 33 males) both in USA and Italy. Age at first observation ranged between newborn and 17 years. Twenty patients have been followed from 4 months to 23 years. The deletion proximal breakpoint varied from 4p15.32 to 4p16.3, and, by FISH, was terminal and included both WHSCR. Deletion was detected by standard cytogenetics in 44/87 (50.5%) patients, whereas FISH was necessary in the other 43 (49.5%). Array-CGH analysis at 1 Mb resolution was performed in 34/87 patients, and, in 15/34 (44%), showed an unbalanced translocation leading to both a 4p monosomy and a partial trisomy for another chromosome arm. Six more patients had been previously shown to have an unbalanced translocation by karyotype analysis or FISH with a WHS-specific probe. Sixty-five of 87 patients had an apparent pure, de novo, terminal deletion; and 1/87 a tandem duplication of 4p16.1p16.3 associated with 4p16.3pter deletion. Age at diagnosis varied between 7 months gestation and 16 years. Ninety-three percent had a seizure disorder with a good outcome; 80% had prenatal onset growth deficiency followed by short stature and slow weight gain; 60% had skeletal anomalies; 50% had heart lesions; 50% had abnormal tooth development; and 40% had hearing loss. Distinctive EEG findings were seen in 90%. Structural CNS anomalies were detected in 80%. Global developmental delay of varying degrees was present in all patients. Almost 50% was able to walk either alone or with support. Hypotonia was present in virtually all patients. A global improvement was observed in all individuals, over time. Our survey has also shown how the characteristic facial phenotype tends to be less pronounced in those patients with a smaller deletion, and microcephaly is not observed in the patients with certain cryptic unbalanced translocations. © 2008 Wiley-Liss, Inc. [source]


Severe perinatal hypophosphatasia due to homozygous deletion of T at nucleotide 1559 in the tissue nonspecific alkaline phosphatase gene

PRENATAL DIAGNOSIS, Issue 9 2003
Hideaki Sawai
Abstract Objectives Hypophosphatasia is an inherited disorder characterized by defective bone mineralization and deficiency of tissue nonspecific alkaline phosphatase (TNSALP) activity. This disorder is caused by various mutations in the TNSALP gene. We report here hypophosphatasia in two siblings, both of them severely affected by the perinatal (lethal) type. Methods We diagnosed the first infant by clinical and radiologic manifestations, and laboratory findings. Laboratory findings were characterized by deficiency of serum alkaline phosphatase. Both parents and the second infant were then analyzed by molecular techniques. Results The radiograph of the first infant showed severe hypomineralization of the skeleton. Molecular analysis of the second infant showed that this condition was caused by a homozygous single T nucleotide deletion at cDNA number 1559 (1559delT). Both parents were heterozygous carriers for this mutation, although they were not consanguineous. Conclusion This mutation has been frequently found in Japanese hypophosphatasia patients, but this is the first observation of a homozygous deletion. This report shows that homozygosity for the 1559delT mutation of the TNSALP gene results in a severe lethal phenotype. Copyright © 2003 John Wiley & Sons, Ltd. [source]


Characteristic fragmentation of bacteriohopanepolyols during atmospheric pressure chemical ionisation liquid chromatography/ion trap mass spectrometry

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 24 2003
Helen M. Talbot
Bacteriohopanepolyols (BHPs) fragment via characteristic pathways during atmospheric pressure chemical ionisation liquid chromatography/ion trap mass spectrometry (APCI-LC/MSn). Comparison of the MS2 spectra of bacteriohopane-32,33,34,35-tetrol (BHT) and 2, -methylbacteriohopane-32,33,34,35-tetrol has confirmed the previously proposed ring-C cleavage occurring between C-9 and 11 and C-8 and 14. This fragmentation, diagnostic of all hopanoids, also occurs in BHPs containing an amino group (-NH2) at C-35 although the higher relative stability of the ion limits this fragmentation to a minor process after protonation of the basic nitrogen function. Studies of a number of cell cultures including a prochlorophyte (Prochlorothrix hollandica) and a cyanobacterium (Chlorogloeopsis LA) demonstrate the power of this technique to detect composite BHPs with a complex biological functionality at C-35. We also report the first observation of intact pentafunctionalised bacteriohopanepolyols using this method. Copyright © 2003 John Wiley & Sons, Ltd. [source]


Incomplete penetrance of the NOD2 E383K substitution among members of a pediatric granulomatous arthritis pedigree

ARTHRITIS & RHEUMATISM, Issue 6 2009
Frank T. Saulsbury
Pediatric granulomatous arthritis (PGA) has been associated with 12 different substitutions in the NOD2 gene thus far. We report a case of PGA in a 6-year-old girl with the NOD2 E383K gene substitution. Genotype analysis of the patient's family members revealed that her affected paternal aunt, as well as her asymptomatic father and 3 younger siblings, were heterozygous for the E383K substitution. The patient's mother did not have a NOD2 mutation. This is the first report of a pedigree in which 4 asymptomatic members carry the E383K substitution in NOD2, as well as the first observation of an asymptomatic carrier state for any of the NOD2 "Blau mutations." [source]


The Troughton & Simms transit circle of Coimbra Astronomical Observatory from the 1850s: An example of the dissemination of technological developments

ASTRONOMISCHE NACHRICHTEN, Issue 6 2009
V. Bonifácio
Abstract Yesterday, as today, technological developments led by large and expensive instrumental projects are later on disseminated to smaller and more affordable devices. In 1847, Airy requested a new transit circle for the Greenwich Observatory. When the first observation was performed, on 4 January 1851, Airy's Greenwich Transit Circle (ATC) was the largest instrument of its class in the world. The construction of the ATC implied solving several technical difficulties, for example, the maintenance of the instrument rigidity and the illumination of the graduated circle and telescope field of view. After the ATC completion Troughton & Simms stand at the 1851 Great London Exhibition included two small transit instruments which were praised for their telescope field of view/eyepiece wires illumination. One of which, was based upon the design implemented beforehand on the ATC. In this paper we will discuss the field and eyepiece wire illumination innovations introduced on the ATC and the Simms transit instruments exhibited in 1851. We will also describe the small Troughton & Simms transit circle currently belonging to Coimbra Astronomical Observatory collection that is, we believe, one of the earliest implementation of this ATC lead development (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]