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1.
Sci Rep ; 9(1): 8848, 2019 06 20.
Artigo em Inglês | MEDLINE | ID: mdl-31222116

RESUMO

After 53 years of quiescence, Mount Agung awoke in August 2017, with intense seismicity, measurable ground deformation, and thermal anomalies in the summit crater. Although the seismic unrest peaked in late September and early October, the volcano did not start erupting until 21 November. The most intense explosive eruptions with accompanying rapid lava effusion occurred between 25 and 29 November. Smaller infrequent explosions and extrusions continue through the present (June 2019). The delay between intense unrest and eruption caused considerable challenges to emergency responders, local and national governmental agencies, and the population of Bali near the volcano, including over 140,000 evacuees. This paper provides an overview of the volcanic activity at Mount Agung from the viewpoint of the volcano observatory and other scientists responding to the volcanic crisis. We discuss the volcanic activity as well as key data streams used to track it. We provide evidence that magma intruded into the mid-crust in early 2017, and again in August of that year, prior to intrusion of an inferred dike between Mount Agung and Batur Caldera that initiated an earthquake swarm in late September. We summarize efforts to forecast the behavior of the volcano, to quantify exclusion zones for evacuations, and to work with emergency responders and other government agencies to make decisions during a complex and tense volcanic crisis.

2.
Org Biomol Chem ; 16(5): 825-831, 2018 01 31.
Artigo em Inglês | MEDLINE | ID: mdl-29327743

RESUMO

Recently, we developed a novel non-fragmenting quaternary ammonium ionization tag for the mass spectrometric sensitive sequencing of peptides, based on the N-spiro proline residue (5-azoniaspiro[4.4.]nonyl-carbonyl). Herein, we present an unexpected racemization and the hydrogen-deuterium exchange (HDX) at the α-C atom of the proline derivative under basic aqueous conditions (1% water solution of triethylamine). The deuterium atom, substituted for the α-C atom, does not undergo back-exchange under acidic aqueous conditions which makes the deuterated isotopologue a promising stabile isotope-coded internal standard for quantitative analysis by mass spectrometry. The applicability of the prepared isotopologues of the quaternary ammonium salt labeled peptides for quantification experiments using the isotopic dilution method was also examined.

3.
Br Poult Sci ; 52(5): 537-40, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22029779

RESUMO

Genetic parameters for mean and for environmental variation in egg weight, body weight, age at first egg, and egg production were estimated in eight layer lines. The data were recorded from years 1999-2007, with on average of 6500 birds per line. An iterative mean-variance REML method was applied with a sire-plus-dam model for mean, a sire model for variance, and a fixed effect of hatch within generation for both mean and variance. The estimated heritability of environmental variation averaged about 5% for body weight, 3% for egg weight, and 11% for age at first egg, but was inconsistent among the lines for egg production (0-15%). Correlations between means and variances were slightly positive for body weight, egg weight, and age at first egg; and strongly negative for egg production. Age at first egg had the highest heritability of environmental variation; and favourable correlations with egg production and with variation in other production traits indicate that reducing variation in this trait may have potential benefits for the breeding industry.


Assuntos
Cruzamento , Galinhas/genética , Heterogeneidade Genética , Oviparidade , Animais , Peso Corporal , Galinhas/fisiologia , Feminino , Modelos Genéticos , Óvulo/fisiologia , Polônia
4.
J Anim Breed Genet ; 127(4): 255-60, 2010 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-20646112

RESUMO

We evaluate the extent to which changes in phenotypic variation among generations of populations kept in the same environment are due to changes in genetic (V(A)) or in environmental (V(E)) variance. Data were available on body weight of adult poultry on a total of 89186 birds (mainly females) from six generations of each of seven lines of layers. There was substantial heterogeneity of variation between generations, shown to be in both V(A) and V(E) components. Based on the Akaike information criterion (AIC), the best fit was with both components changing, and a better fit was obtained if V(A)/V(E) (i.e. heritability) or V(E), rather than V(A), was assumed constant. In analyses of quantitative genetic data spanning environmental groups, attention should be paid to whether and how the variance components change among groups before undertaking detailed variance partition that may be sensitive to such changes.


Assuntos
Galinhas/anatomia & histologia , Galinhas/genética , Meio Ambiente , Variação Genética , Fenótipo , Animais , Peso Corporal , Galinhas/fisiologia , Ovos , Feminino , Masculino , Linhagem
5.
Phys Rev Lett ; 100(10): 107202, 2008 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-18352227

RESUMO

The magnetic linear dichroism of the gadolinium 4f core level is studied in a time-resolved photoemission experiment employing laser pump- and synchrotron-radiation probe pulses. Upon optical excitation of the 5d6s valence electrons with femtosecond laser pulses, the magnetic order in the 4f spin system is reduced. Remarkably, the linear dichroism remains at 80% of the equilibrium contrast while the lattice temperature reaches the Curie temperature due to electron-phonon scattering. Contrasting itinerant ferromagnets, this shows that equilibration between the lattice and spin subsystems takes in Gd about 80 ps and is established in parallel with heat diffusion.

6.
Biopolymers ; 89(3): 220-34, 2008 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-18041062

RESUMO

Two series of dehydropeptides of the general formulae Boc-Gly-X-Phe-p-NA, Boc-Gly-Gly-X-Phe-p-NA, Gly-X-Gly-Phe-p-NA.TFA, and Boc-Gly-X-Gly-Phe-p-NA, with X = Delta(Z)Phe and DeltaAla, were studied with NMR in DMSO and CDCl(3)-DMSO, and with CD in MeOH, MeCN, and TFE. The NMR spectra measured in DMSO suggest that peptides with the DeltaPhe residue next to Phe are folded whereas peptides with Gly between DeltaPhe and Phe are less ordered. NMR spectra of DeltaAla-containing peptides indicate that these peptides are flexible and their conformational equilibria are populated by many different conformations. The CD spectra show that conformational properties of the peptides studied are distinctly influenced by a mutual position of the dehydroamino acid residue and the p-NA group. They indicate that all dehydropeptides with the DeltaPhe residue, Boc-Gly-DeltaAla-Phe-p-NA, and Boc-Gly-Gly-DeltaAla-Phe-p-NA adopt ordered conformations in all solvents studied, presumably of the beta-turn type. The last two peptides exhibit surprising chiroptical properties. Their spectra show exciton coupling-like couplets in the region of the p-NA group absorption. This shape of CD spectra suggests a rigid, chiral conformation with a fixed disposition of the p-NA group. The CD spectra indicate that Boc-Gly-DeltaAla-Gly-Phe-p-NA and Gly-DeltaAla-Gly-Phe-p-NA.TFA are unordered, independently of the solvent.


Assuntos
Alanina/análogos & derivados , Amidas/química , Dipeptídeos/química , Modelos Químicos , Fenilalanina/análogos & derivados , Alanina/química , Dicroísmo Circular , Cristalografia , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Fenilalanina/química , Conformação Proteica , Espectroscopia de Infravermelho com Transformada de Fourier
7.
Phys Rev Lett ; 98(9): 097401, 2007 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-17359194

RESUMO

Transient changes of the complex self-energy of the 5d(z2) surface state on Gd(0001) after intense optical excitation are investigated by femtosecond time-resolved photoemission. We observe an ultrafast (<100 fs) broadening of the linewidth due to e-e scattering followed by a decrease of the binding energy due to thermal expansion of the lattice. In addition, we resolve a periodic breathing of the band structure which originates from a coherent phonon. An amplitude of 1 pm is derived from the binding energy shift upon lattice displacement calculated by density functional theory.

8.
Phys Rev Lett ; 99(19): 197001, 2007 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-18233106

RESUMO

Time-resolved photoelectron spectroscopy is employed to study the dynamics of photoexcited electrons in optimally doped Bi{2}Sr{2}CaCu{2}O{8+delta} (Bi-2212). Hot electrons thermalize in less than 50 fs and dissipate their energy on two distinct time scales (110 fs and 2 ps). These are attributed to the generation and subsequent decay of nonequilibrium phonons, respectively. We conclude that 20% of the total lattice modes dominate the coupling strength and estimate the second momentum of the Eliashberg coupling function lambdaOmega{0}{2}=360+/-30 meV{2}. For the typical phonon energy of copper-oxygen bonds (Omega{0} approximately 40-70 meV), this results in an average electron-phonon coupling lambda<0.25.

9.
J Vet Med A Physiol Pathol Clin Med ; 53(10): 501-8, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-17105570

RESUMO

The study was performed to determine the hormonal status of mature germline chimeras obtained by blastodermal cell transfer from chicken embryos of a donor breed [Green-legged Partridgelike breed (GP) x Araucana (AR)] to those of a recipient breed [White Leghorn (WL)] being at the same stage of embryonic development. The egg-laying chimeras and WL hens (control) of the same age were used in the experiment. At first, blood samples were taken from each bird at 0.5, 5, 12.5 and 18.5 h following oviposition. Subsequently, the chimeras and the WL hens were decapitated 1-2 h after ovulation. A stroma and the following follicles were isolated from the ovary: white normal (1-4, 4-6 and 6-8 mm), white atretic and yellow preovulatory follicles (F4-F1). Sex hormones, progesterone (P4), testosterone (T) and oestradiol (E2) in blood plasma and ovarian follicles were determined radioimmunologically. The activity of the 3beta-hydroxysteroid dehydrogenase (3beta-HSD) in the granulosa and theca layers of the follicles was analysed histochemically. In chimeric chickens, a higher level of T in blood plasma during the ovulatory cycle was noticed. However, in the stroma, white prehierarchical and medium-size preovulatory ovarian follicles the level of T was significantly lower. With respect to E2, its elevated levels were found both in blood and in the ovarian follicles. There were no significant differences in P4 concentrations in blood plasma while in ovarian follicles a higher level was observed only in white 6-8 mm follicles. 3beta-HSD activity in granulosa and theca layers of the ovarian follicles in chimeras was not different from that in the WL hens. In conclusion, the results obtained indicate that germline chimeras exhibit significant alterations in sex hormone levels in the ovary and blood plasma, which in turn may affect their reproductive abilities.


Assuntos
Galinhas/metabolismo , Hormônios Esteroides Gonadais/análise , Células da Granulosa/metabolismo , Folículo Ovariano/metabolismo , Oviposição/fisiologia , Células Tecais/metabolismo , Animais , Embrião de Galinha , Galinhas/sangue , Quimera , Estradiol/análise , Estradiol/sangue , Feminino , Hormônios Esteroides Gonadais/sangue , Folículo Ovariano/enzimologia , Progesterona/análise , Progesterona/sangue , Testosterona/análise , Testosterona/sangue
10.
Phys Rev Lett ; 97(6): 067402, 2006 Aug 11.
Artigo em Inglês | MEDLINE | ID: mdl-17026203

RESUMO

Femtosecond time-resolved photoemission is used to investigate the time evolution of electronic structure in the Mott insulator 1T-TaS2. A collapse of the electronic gap is observed within 100 femtoseconds after optical excitation. The photoemission spectra and the spectral function calculated by dynamical mean field theory show that this insulator-metal transition is driven solely by hot electrons. A coherently excited lattice displacement results in a periodic shift of the spectra lasting for 20 ps without perturbing the insulating phase. This capability to disentangle electronic and phononic excitations opens new directions to study electron correlation in solids.

11.
Phys Rev Lett ; 95(13): 137402, 2005 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-16197177

RESUMO

Femtosecond electron and spin dynamics of the Gd(0001) surface are investigated by time-resolved photoemission and second harmonic generation. Upon optical excitation the spin polarization of the surface state is reduced by half while its exchange splitting remains nearly unchanged. Electron-magnon interaction is proposed to facilitate electron-spin-flip scattering among spin-mixed surface and bulk states, which provides a mechanism for ultrafast demagnetization.

12.
Biopolymers ; 70(4): 497-511, 2003 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-14648761

RESUMO

The CLX peptide isolated from flax seed has a sequence cyclo-(PPFFILLX), where X is a nonproteinaceous amino acid residue, (2S,4R) 4-amine-N-methylproline. Picur, B.; Lisowski, M.; Siemion, I.Z. Letters Pept Sci 1998, 5, 183-187. The structure of X strongly suggests that this natural amino acid plays a role of the dipeptide moiety with a nonplanar cis peptidomimetic bond. The X residue contains two asymmetrical carbons and thus can appear in four configurations: (2S,4R), (2S,4S), (2R,4S), and (2R,4R). All four diastereoisomers of X were synthesized and characterized as trifluoroacetates of 4-phtalimido-N-methylproline benzylamides. Their full physicochemical characteristics are presented in this article. The synthesis of linear and cyclic analogues of CLX containing all four possible diastereoisomers of X was performed. Additionally, analogues with gamma-aminobutyric acid (GABA) and glycyl-N-methyl-glycine dipeptide [G(Me)G] substituted for X were synthesized. The obtained peptides were purified using HPLC, examined by ESI/MS, and then studied by CD spectroscopy. They were also tested for immunosuppressive activity (PFC in vitro). All of them revealed diverse immunosuppressive activity, however, lower than that of cyclolinopeptide A (CLA) Wieczorek, Z.; Bengtsson, B.; Trojnar, J.; Siemion, I.Z. Peptide Res 1991, 4, 275-283. and cyclosporine A (CsA). Ellis, G.P.; West, G.B. Progress Med Chem 1988, 25, 1-33. The structure of CLX with (2S,4R) 4-amino-N-methylproline was determined by 2-D NMR methods. All amide bonds are in the trans configuration. The cis peptidomimetic group delta-CH(2)-N(CH(3))- is exposed to the outside of the CLX molecule. The peptide contains two loops similar to beta-turns of type IV. Chou, P.Y.; Fasman, G.D. J Mol Biol 1977, 115, 136-715 and has the extended shape flanked by F3 and L7 residues with significant side chain flexibility.


Assuntos
Linho/genética , Peptídeos Cíclicos/biossíntese , Prolina/análogos & derivados , Dicroísmo Circular , Linho/química , Espectroscopia de Ressonância Magnética , Peptídeos/metabolismo , Peptídeos Cíclicos/imunologia , Peptídeos Cíclicos/metabolismo , Conformação Proteica
13.
Poult Sci ; 81(9): 1347-53, 2002 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12269615

RESUMO

Blastoderm cells from chicken embryos of a donor breed (Green-legged Partridgelike; GP) were transferred to embryos of a recipient breed (White Leghorn; WL) to form chimeric progeny that, after inter se mating, permitted successful reconstitution of the donor breed. Among 23 chimeric chicks hatched from WL embryos injected with GP cells, 20 (87%) were raised until maturity, and progeny were tested by mating with GP birds to determine the ability of blastodermal cells to form germline chimeras. Six of the tested birds (30%) produced recipient-derived and donor-derived offspring, indicating that they were germline chimeras. The mean percentages of donor-derived germ cells in these birds were 21.1 (17.6 to 50.0%) and 16.9 (5.3 to 23.1%) in males and females, respectively. Among 477 chicks, resulting from mating the germline chimeric male with four germline chimeric females, 10 chicks (2.1%) exhibited a GP phenotype, indicating that the original donor stock had been reconstituted. Only one germline chimeric hen produced GP offspring, but the expected and calculated percentages of GP offspring were similar (2.99 and 2.08, respectively). Two methods of DNA analyses (RFLP and PCR amplification of polymorphic microsatellite loci) of chimeras and their offspring indicated that through mating of a relatively small number of chimeras it is possible to reconstitute a highly diverse population.


Assuntos
Galinhas/genética , Quimera/genética , Mutação em Linhagem Germinativa , Animais , Blastoderma/transplante , Embrião de Galinha/fisiologia , Cruzamentos Genéticos , Feminino , Masculino
14.
Phys Rev Lett ; 86(8): 1602-5, 2001 Feb 19.
Artigo em Inglês | MEDLINE | ID: mdl-11290203

RESUMO

We show that the paramagnetic reentrant effect observed in experiments by Mota et al. in mesoscopic cylinders made of a normal metal in proximity with a superconductor, can be caused by paramagnetic persistent currents flowing on the outer shell of the cylinder.

15.
Eur J Biochem ; 260(2): 325-35, 1999 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-10095766

RESUMO

The Streptomyces lividans DnaA protein (73 kDa) consists, like other bacterial DnaA proteins, of four domains; it binds to 19 DnaA boxes in the complex oriC region. The S. lividans DnaA protein differs from others in that it contains an additional stretch of 120 predominantly acidic amino acids within domain II. Interactions between the DnaA protein and the two DnaA boxes derived from the promoter region of the S. lividans dnaA gene were analysed in vitro using three independent methods: Dnase-I-footprinting experiments, mobility-shift assay and surface plasmon resonance (SPR). The Dnase-I-footprinting analysis showed that the wild-type DnaA protein binds to both DnaA boxes. Thus, as in Escherichia coli and Bacillus subtilis, the S. lividans dnaA gene may be autoregulated. SPR analysis showed that the affinity of the DnaA protein for a DNA fragment containing both DnaA boxes from the dnaA promoter region (KD = 1.25 nM) is 10 times higher than its affinity for the single 'strong' DnaA box (KD = 12.0 nM). The mobility-shift assay suggests the presence of at least two classes of complex containing different numbers of bound DnaA molecules. The above data reveal that the DnaA protein binds to the two DnaA boxes in a cooperative manner. To deduce structural features of the Streptomyces domain II of DnaA protein, the amino acid DnaA sequences of three Streptomyces species were compared. However, according to the secondary structure prediction, Streptomyces domain II does not contain any common relevant secondary structural element(s). It can be assumed that domain II of DnaA protein can play a role as a flexible protein spacer between the N-terminal domain I and the highly conserved C-terminal part of DnaA protein containing ATP-binding domain III and DNA-binding domain IV.


Assuntos
Proteínas de Bactérias/metabolismo , Proteínas de Ligação a DNA/metabolismo , Streptomyces/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Sequência de Bases , Técnicas Biossensoriais , Western Blotting , Pegada de DNA , DNA Fúngico/química , Proteínas de Ligação a DNA/genética , Eletroforese em Gel de Poliacrilamida , Dados de Sequência Molecular , Peso Molecular , Regiões Promotoras Genéticas , Alinhamento de Sequência , Streptomyces/genética
16.
J Pept Res ; 51(2): 96-102, 1998 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-9516043

RESUMO

Juvenile hormone binding protein (JHBP) from hemolymph of Galleria mellonella is a single-chain glycoprotein of molecular mass near 25,880 containing no Trp residues. The fourth derivative of the protein absorption spectrum shows the characteristic vibrational components of the phenylalanine spectrum within the range 240-270 nm. At longer wavelengths two main bands 0-0 and 0+800 cm(-1) appear, caused by vibrational levels of electronic transition, pi-->pi*, in the tyrosine residues, with maxima at 279 nm and 286 nm, respectively. Two intersection points of the second derivative absorption band with abscissa at about 288.8 nm and 283 nm were analysed for estimation of the environment polarity of Tyr residues in the JHBP molecule. The results obtained suggest that JHBP contains at least two classes of Tyr residues with very apolar environment, similar to that found in azurine. In the JHBP-JH complex only one class of Tyr residues located in a very apolar environment was found, and a small perturbation of disulphide bridges was deduced from the UV-difference spectrum. Ligand perturbation appears as a minimum at 243 nm of the UV-difference spectrum. Comparison of the circular dichroism (CD) spectra for free JHBP with the CD spectra for the JHBP-JH complex monitored in the far-UV (190-240 nm) region indicates rather small differences in the secondary structure of the protein. Although ligand binding induces distinct changes in the near-UV (250-300 nm) region of the CD spectrum of JHBP, it is apparent where both Tyr and Phe residues contribute.


Assuntos
Proteínas de Transporte/metabolismo , Dicroísmo Circular , Proteínas de Insetos , Mariposas , Sesquiterpenos/metabolismo , Espectrofotometria Ultravioleta , Animais , Proteínas de Transporte/química , Hemolinfa/química , Larva , Fenilalanina/química , Ligação Proteica , Estrutura Secundária de Proteína , Sesquiterpenos/química , Tirosina/química
17.
J Pept Res ; 49(5): 415-20, 1997 May.
Artigo em Inglês | MEDLINE | ID: mdl-9211222

RESUMO

Linear and cyclic analogues of cyclolinopeptide A (CLA) in which one or both phenylalanine residues in fragment Pro6-Pro7-Phe8-Phe9 were substituted by their sulfonated derivatives have been synthesized by SPPS method and cyclization with the BOP reagent. The peptides were examined for their immunosuppressive activity in the humoral and cellular immune response by PFC and DTH tests. All of the analogues retain some immunosuppressive activity of native CLA. Their CD spectra confirm that the optical activity of aromatic residues in CLA depends on their position in the peptide chain. Only the residue in position 8 seems to be optically active. CD spectrum of the cyclic analogue modified in position 9 is very similar to that of native CLA which correlates with its high biological activity. The chiroptical properties of the p-sulfonated Phe-residue are established.


Assuntos
Imunossupressores/síntese química , Imunossupressores/farmacologia , Peptídeos Cíclicos/química , Peptídeos Cíclicos/síntese química , Peptídeos Cíclicos/farmacologia , Conformação Proteica , Ácidos Sulfônicos , Sequência de Aminoácidos , Animais , Formação de Anticorpos/efeitos dos fármacos , Dicroísmo Circular , Eritrócitos/imunologia , Hipersensibilidade Tardia , Imunossupressores/química , Camundongos , Camundongos Endogâmicos CBA , Ovinos , Relação Estrutura-Atividade
18.
Int J Pept Protein Res ; 48(4): 347-56, 1996 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8919055

RESUMO

The crystal structure and solution conformation of Ac-Pro-deltaAla-NHCH3 and the solution conformation of Ac-Pro-(E)-deltaAbu-NHCH3 were investigated by X-ray diffraction method and NMR, FTIR and CD spectroscopies. Ac-Pro-deltaAla-NHCH3 adopts an extended-coil conformation in the crystalline state, with all-trans peptide bonds and the deltaAla residue being in a C5 form, phi(1)=-71.4(4), psi(1)=-16.8(4), phi(2)= -178.4(3) and psi(2)= 172.4(3) degrees. In inert solvents the peptide also assumes the C5 conformation, but a gamma-turn on the Pro residue cannot be ruled out. In these solvents Ac-Pro-(E)-deltaAbu-NHCH3 accommodates a beta(II)-turn, but a minor conformer with a nearly planar disposition of the CO-NH and C=C bonds (phi(2) approximately 0 degrees) is also present. Previous spectroscopic studies of the (Z)-substituted dehydropeptides Ac-Pro-(Z)-deltaAbu-NHCH3 and Ac-Pro-deltaVal-NHCH3 reveal that both peptides prefer a beta(II)-turn in solution. Comparison of conformations in the family of four Ac-Pro-deltaXaa-NHCH3 peptides let us formulate the following order of their tendency to adopt a beta-turn in solution: (Z)-deltaAbu > (E)-deltaAbu > deltaVal; deltaAla does not. None of the folded structures formed by the four compounds is stable in strongly solvating media.


Assuntos
Alanina/análogos & derivados , Dipeptídeos/química , Estrutura Secundária de Proteína , Alanina/química , Dicroísmo Circular , Espectroscopia de Ressonância Magnética , Prolina/química , Solventes/química , Espectroscopia de Infravermelho com Transformada de Fourier , Estereoisomerismo , Difração de Raios X
19.
Int J Pept Protein Res ; 48(3): 286-91, 1996 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-8897097

RESUMO

The object of our studies was the synthesis and conformational and biological evaluation of the series of 14 analogues of the insect neuropeptide, proctolin. The analogues were obtained by replacement of the native L-amino acids by their D-isomers in one, two, and all positions. Biological effects of the peptides were examined by cardioexcitatory test on the heart of yellow mealworm, Tenebrio molitor, in vitro. In biotest performed on insects, D-Arg-D-Tyr-D-Leu-D-Pro-D-Thr, [D-Arg(N-G-nitro)1,D-Leu3]-, [D-Arg1,D-Leu3]-, [D-Tyr2,D-Thr5]- and [D-Arg1,D-Pro4]-proctolin exert high agonistic activity of proctolin on the heart of insects at 10(-11) - 10(-10) M concentrations. The proctolin analogue containing only D-amino acid residues in the peptide chain unexpectedly shows a much higher cardioexcitatory effect than the native peptide. Moreover, preliminary CD and NMR conformational studies show that proctolin analogues investigated here seem to prefer rather ordered structures, although their conformations differ in some cases.


Assuntos
Neuropeptídeos , Oligopeptídeos/química , Tenebrio/efeitos dos fármacos , Aminoácidos/química , Animais , Espectroscopia de Ressonância Magnética , Oligopeptídeos/síntese química , Oligopeptídeos/farmacologia , Conformação Proteica
20.
Anat Rec ; 245(1): 53-6, 1996 May.
Artigo em Inglês | MEDLINE | ID: mdl-8731040

RESUMO

BACKGROUND: The objective of this study was to thoroughly examine the in vivo angiogenesis activity of human recombinant tumor necrosis factor alpha (rhTNF). METHODS: rhTNF (0.5 ng to 1.0 microgram) was incorporated into the slow release polymers Hydron or HYPAN and implanted into the rabbit cornea. Release of biologically active rhTNF from the polymers was determined with the L929 cytotoxicity assay. RESULTS: All concentrations tested failed to elicit capillary formation beyond that observed for controls. Less than 2% of the rhTNF was released from the Hydron over 7 days. HYPAN released five times the amount of rhTNF in vitro, but even at doses of 500 ng (104.3 ng suggested release) no angiogenesis was stimulated. CONCLUSIONS: Under the circumstances tested, rhTNF is not angiogenic in vivo.


Assuntos
Córnea/irrigação sanguínea , Neovascularização Fisiológica/efeitos dos fármacos , Fator de Necrose Tumoral alfa/farmacologia , Resinas Acrílicas , Animais , Córnea/citologia , Córnea/efeitos dos fármacos , Portadores de Fármacos , Feminino , Próteses e Implantes , Coelhos , Proteínas Recombinantes , Estatísticas não Paramétricas
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