The electrical and magnetic properties of amorphous Pd-Cu-P alloys

The amorphous phases of the Pd-Cu-P system has been obtained using the technique of rapidly quenching from the liquid state. Broad maxima in the diffraction pattern were obtained in the X-ray diffraction studies which are indicative of a glass-like structure. The composition range over which the amorphous solid phase is retained for the Pd-Cu-P system is (Pd_100-xCu_x)₈₀P₂₀ with 10 ≤ x ≤ 50 and (Pd₆₅Cu₃₅)_100-yP_y with 15 ≤ y ≤ 24 and (Pd₆₀Cu₄₀)_100-yP_y with 15 ≤ y ≤ 24.

The electrical resistivity for the Pd-Cu-P alloys decreases with temperature as T² at low temperatures and as T at high temperatures up to the crystallization temperature. The structural scattering model of the resistivity proposed by Sinha and the spin-fluctuation resistivity model proposed by Hasegawa are re-examined in the light of the similarity of this result to the Pt-Ni-P and Pd-Ni-P systems. Objections are raised to these interpretations of the resistivity results and an alternate model is proposed consistent with the new results on Pd-Cu-P and the observation of similar effects in crystalline transition metal alloys. The observed negative temperature coefficients of resistivity in these amorphous alloys are thus interpreted as being due to the modification of the density of states with temperature through the electron-phonon interaction. The weak Pauli paramagnetism of the Pd-Cu-P, Pt-Ni-P and Pd-Ni-P alloys is interpreted as being modifications of the transition d-states as a result of the formation of strong transition metal-metalloid bonds rather than a large transfer of electrons from the glass former atoms (P in this case) to the d-band of the transition metal in a rigid band picture.

Experimental study of the upper hybrid echo in plasmas

The two-pulse stimulated radiation of dense (10^9/cm^3 < ne ≤ 10^(11) /cm^3) nonuniform neon and argon afterglow plasma columns longitudinally immersed in a magnetic field is studied. The magnetic field is very homogeneous over the plasma volume (∆B/B~.01%). If the S-band microwave pulses' center frequency is such that they resonantly excite a narrow band of plasma upper hybrid oscillations close to the maximum upper hybrid frequency of the column, strong two pulse echoes are observed. This new echo process is called the upper hybrid echo. The echo spectrum, echo power and echo width were studied as a function of the pulse peak power P, pulse separation τ, relative density (ω_(po)/ω)^2, and relative cyclotron frequency (ω_c/ω). The complex but systematic variations of the echo properties as a function of the above-mentioned parameters arc found to be in qualitative agreement with those predicted by a theory of Gould and Blum based upon a simple nonuniform unidimensional cold plasma slab model. The possible effects of electron neutral and electron ion collisions not retained in the theoretical model are discussed.

The existence of a new type of cyclotron echo, different from that of Hill and Kaplan and not predicted by the Blum and Gould model is documented. It is believed to be also of a collective effect nature and can probably be described in terms of a theory retaining some hot plasma effects.

Structure-, stereochemistry-, and metal-regulated DNA binding/cleaving molecules

In the cell, the binding of proteins to specific sequences of double helical DNA is essential for controlling the processes of protein synthesis (at the level of DNA transcription) and cell proliferation (at the level of DNA replication). In the laboratory, the sequence-specific DNA binding/cleaving properties of restriction endonuclease enzymes (secreted by microorganisms to protect them from foreign DNA molecules) have helped to fuel a revolution in molecular biology. The strength and specificity of a protein:DNA interaction depend upon structural features inherent to the protein and DNA sequences, but it is now appreciated that these features (and therefore protein:DNA complexation) may be altered (regulated) by other protein:DNA complexes, or by environmental factors such as temperature or the presence of specific organic molecules or inorganic ions. It is also now appreciated that molecules much smaller than proteins (including antibiotics of molecular weight less than 2000 and oligonucleotides) can bind to double-helical DNA in sequence-specific fashion. Elucidation of structural motifs and microscopic interactions responsible for the specific molecular recognition of DNA leads to greater understanding of natural processes and provides a basis for the design of novel sequence-specific DNA binding molecules. This thesis describes the synthesis and DNA binding/cleaving characteristics of molecules designed to probe structural, stereochemical, and environmental factors that regulate sequence-specific DNA recognition.

Chapter One introduces the DNA minor groove binding antibiotics Netropsin and Distamycin A, which are di- and tri(N-methylpyrrolecarboxamide) peptides, respectively. The method of DNA affinity cleaving, which has been employed to determine DNA binding properties of designed synthetic molecules is described. The design and synthesis of a series of Netropsin dimers linked in tail-to-tail fashion (by oxalic, malonic, succinic, or fumaric acid), or in head-to-tail fashion (by glycine, β-alanine, and γ-aminobutanoic acid (Gaba)) are presented. These Bis(Netropsin)s were appended with the iron-chelating functionality EDTA in order to make use of the technique of DNA affinity cleaving. Bis(Netropsin)-EDTA compounds are analogs of penta(N-methylpyrrolecarboxamide)-EDTA (P5E), which may be considered a head-to-tail Netropsin dimer linked by Nmethylpyrrolecarboxamide. Low- and high-resolution analysis of pBR322 DNA affinity cleaving by the iron complexes of these molecules indicated that small changes in the length and nature of the linker had significant effects on DNA binding/cleaving efficiency (a measure of DNA binding affinity). DNA binding/cleaving efficiency was found to decrease with changes in the linker in the order β-alanine > succinamide > fumaramide > N-methylpyrrolecarboxamide > malonamide >glycine, γ-aminobutanamide > oxalamide. In general, the Bis(Netropsin)-EDTA:Fe compounds retained the specificity for seven contiguous A:T base pairs characteristic of P5E:Fe binding. However, Bis(Netropsin)Oxalamide- EDTA:Fe exhibited decreased specificity for A:T base pairs, and Bis(Netropsin)-Gaba-EDT A:Fe exhibited some DNA binding sites of less than seven base pairs. Bis(Netropsin)s linked with diacids have C₂-symmmetrical DNA binding subunits and exhibited little DNA binding orientation preference. Bis(Netropsin)s linked with amino acids lack C₂-symmetrical DNA binding subunits and exhibited higher orientation preferences. A model for the high DNA binding orientation preferences observed with head-to-tail DNA minor groove binding molecules is presented.

Chapter Two describes the design, synthesis, and DNA binding properties of a series of chiral molecules: Bis(Netropsin)-EDTA compounds with linkers derived from (R,R)-, (S,S)-, and (RS,SR)-tartaric acids, (R,R)-, (S,S)-, and (RS,SR)-tartaric acid acetonides, (R)- and (S)-malic acids, N ,N-dimethylaminoaspartic acid, and (R)- and (S)-alanine, as well as three constitutional isomers in which an N-methylpyrrolecarboxamide (P1) subunit and a tri(N-methylpyrrolecarboxamide)-EDTA (P3-EDTA) subunit were linked by succinic acid, (R ,R)-, and (S ,S)-tartaric acids. DNA binding/cleaving efficiencies among this series of molecules and the Bis(Netropsin)s described in Chapter One were found to decrease with changes in the linker in the order β-alanine > succinamide > P1-succinamide-P3 > fumaramide > (S)-malicamide > N-methylpyrrolecarboxamide > (R)-malicamide > malonamide > N ,N-dimethylaminoaspanamide > glycine = Gaba = (S,S)-tartaramide = P1-(S,S)-tanaramide-P3 > oxalamide > (RS,SR)-tartaramide = P1- (R,R)-tanaramide-P3 > (R,R)-tartaramide (no sequence-specific DNA binding was detected for Bis(Netropsin)s linked by (R)- or (S)-alanine or by tartaric acid acetonides). The chiral molecules retained DNA binding specificity for seven contiguous A:T base pairs. From the DNA affinity cleaving data it could be determined that: 1) Addition of one or two substituents to the linker of Bis(Netropsin)-Succinamide resulted in stepwise decreases in DNA binding affinity; 2) molecules with single hydroxyl substituents bound DNA more strongly than molecules with single dimethylamino substituents; 3) hydroxyl-substituted molecules of (S) configuration bound more strongly to DNA than molecules of (R) configuration. This stereochemical regulation of DNA binding is proposed to arise from the inherent right-handed twist of (S)-enantiomeric Bis(Netropsin)s versus the inherent lefthanded twist of (R)-enantiomeric Bis(Netropsin)s, which makes the (S)-enantiomers more complementary to the right-handed twist of B form DNA.

Chapter Three describes the design and synthesis of molecules for the study of metalloregulated DNA binding phenomena. Among a series of Bis(Netropsin)-EDTA compounds linked by homologous tethers bearing four, five, or six oxygen atoms, the Bis(Netropsin) linked by a pentaether tether exhibited strongly enhanced DNA binding/cleaving in the presence of strontium or barium cations. The observed metallospecificity was consistent with the known affinities of metal cations for the cyclic hexaether 18-crown-6 in water. High-resolution DNA affinity cleaving analysis indicated that DNA binding by this molecule in the presence of strontium or barium was not only stronger but of different sequence-specificity than the (weak) binding observed in the absence of metal cations. The metalloregulated binding sites were consistent with A:T binding by the Netropsin subunits and G:C binding by a strontium or barium:pentaether complex. A model for the observed positive metalloregulation and novel sequence-specificity is presented. The effects of 44 different cations on DNA affinity cleaving by P5E:Fe were examined. A series of Bis(Netropsin)-EDTA compounds linked by tethers bearing two, three, four, or five amino groups was also synthesized. These molecules exhibited strong and specific binding to A:T rich regions of DNA. It was found that the iron complexes of these molecules bound and cleaved DNA most efficiently at pH 6.0-6.5, while P5E:Fe bound and cleaved most efficiently at pH 7.5-8.0. Incubating the Bis(Netropsin) Polyamine-EDTA:Fe molecules with K₂PdCl₄ abolished their DNA binding/cleaving activity. It is proposed that the observed negative metalloregulation arises from kinetically inert Bis(Netropsin) Polyamine:Pd(II) complexes or aggregates, which are sterically unsuitable for DNA complexation. Finally, attempts to produce a synthetic metalloregulated DNA binding protein are described. For this study, five derivatives of a synthetic 52 amino acid residue DNA binding/cleaving protein were produced. The synthetic mutant proteins carried a novel pentaether ionophoric amino acid residue at different positions within the primary sequence. The proteins did not exhibit significant DNA binding/cleaving activity, but they served to illustrate the potential for introducing novel amino acid residues within DNA binding protein sequences, and for the development of the tricyclohexyl ester of EDTA as a superior reagent for the introduction of EDT A into synthetic proteins.

Chapter Four describes the discovery and characterization of a new DNA binding/cleaving agent, [SalenMn(III)]OAc. This metal complex produces single- and double-strand cleavage of DNA, with specificity for A:T rich regions, in the presence of oxygen atom donors such as iodosyl benzene, hydrogen peroxide, or peracids. Maximal cleavage by [SalenMn(III)]OAc was produced at pH 6-7. A comparison of DNA singleand double-strand cleavage by [SalenMn(III)]⁺ and other small molecules (Methidiumpropyl-EDTA:Fe, Distamycin-EDTA:Fe, Neocarzinostatin, Bleomycin:Fe) is presented. It was found that DNA cleavage by [SalenMn(III)]⁺ did not require the presence of dioxygen, and that base treatment of DNA subsequent to cleavage by [SalenMn(III)]⁺ afforded greater cleavage and alterations in the cleavage patterns. Analysis of DNA products formed upon DNA cleavage by [SalenMn(III)] indicated that cleavage was due to oxidation of the sugar-phosphate backbone of DNA. Several mechanisms consistent with the observed products and reaction requirements are discussed.

Chapter Five describes progress on some additional studies. In one study, the DNA binding/cleaving specificities of Distamycin-EDTA derivatives bearing pyrrole N-isopropyl substituents were found to be the same as those of derivatives bearing pyrrole N-methyl substituents. In a second study, the design of and synthetic progress towards a series of nucleopeptide activators of transcription are presented. Five synthetic plasmids designed to test for activation of in vitro run-off transcription by DNA triple helix-forming oligonucleotides or nucleopeptides are described.

Chapter Six contains the experimental documentation of the thesis work.

Avaliação in vitro da variação do torque de remoção de parafusos para fixação de pilares protéticos submetidos a ciclos de parafusamento e desparafusamento

O afrouxamento dos parafusos protéticos é descrito na literatura como uma das complicações mais frequentes das próteses sobre implantes. Durante sua confecção, os profissionais sentem necessidade de remover várias vezes as próteses e/ou componentes protéticos, soltando e re-apertando os parafusos repetidamente. O principal objetivo deste trabalho foi avaliar a variação do torque de remoção de parafusos de fixação de pilares protéticos a implantes osteointegráveis após sucessivos ciclos de parafusamento e desparafusamento. Outro objetivo foi avaliar a influência do hexágono da base do pilar no torque de remoção dos parafusos. Para isso, foram utilizados 20 implantes de plataforma regular com hexágono externo e 20 pilares protéticos sextavados, que foram parafusados aos implantes com um parafuso de titânio, aplicando-se a este um torque de 32Ncm, por meio de um torquímetro digital. Os conjuntos implante/pilar/parafuso foram divididos em dois grupos: (1) pilares cujo hexágono da base foram removidos e (2) pilares convencionais, com hexágono na base. Cada conjunto recebeu uma restauração provisória e foi submetido a ciclagem mecânica por 15 minutos. Depois, os parafusos foram removidos, medindo-se o torque de remoção. Esta sequência foi repetida dez vezes e então o parafuso foi trocado por outro sem uso, e mais um ciclo foi realizado. Uma análise de regressão linear demonstrou nos dois grupos uma queda do torque de remoção do parafuso ao longo dos repetidos ciclos de inserção/remoção. A comparação entre os coeficientes da regressão nos dois grupos não revelou diferença entre eles. Também não houve diferença entre as médias das 5 últimas repetições e o 11 ciclo, com o parafuso novo. Concluiu-se que (1) repetidos parafusamentos e desparafusamentos promoveram a diminuição progressiva do torque de remoção dos parafusos, (2) a troca do parafuso por outro sem uso após dez ciclos de inserção/remoção não aumentou sua resistência ao afrouxamento, e (3) a remoção do hexágono da base do pilar protético não exerceu nenhum efeito sobre o torque de remoção do parafuso.

Microelectrode Implants for Spinal Cord Stimulation in Rats

Paralysis is a debilitating condition afflicting millions of people across the globe, and is particularly deleterious to quality of life when motor function of the legs is severely impaired or completely absent. Fortunately, spinal cord stimulation has shown great potential for improving motor function after spinal cord injury and other pathological conditions. Many animal studies have shown stimulation of the neural networks in the spinal cord can improve motor ability so dramatically that the animals can even stand and step after a complete spinal cord transaction.

This thesis presents work to successfully provide a chronically implantable device for rats that greatly enhances the ability to control the site of spinal cord stimulation. This is achieved through the use of a parylene-C based microelectrode array, which enables a density of stimulation sites unattainable with conventional wire electrodes. While many microelectrode devices have been proposed in the past, the spinal cord is a particularly challenging environment due to the bending and movement it undergoes in a live animal. The developed microelectrode array is the first to have been implanted in vivo while retaining functionality for over a month. In doing so, different neural pathways can be selectively activated to facilitate standing and stepping in spinalized rats using various electrode combinations, and important differences in responses are observed.

An engineering challenge for the usability of any high density electrode array is connecting the numerous electrodes to a stimulation source. This thesis develops several technologies to address this challenge, beginning with a fully passive implant that uses one wire per electrode to connect to an external stimulation source. The number of wires passing through the body and the skin proved to be a hazard for the health of the animal, so a multiplexed implant was devised in which active electronics reduce the number of wires. Finally, a fully wireless implant was developed. As these implants are tested in vivo, encapsulation is of critical importance to retain functionality in a chronic experiment, especially for the active implants, and it was achieved without the use of costly ceramic or metallic hermetic packaging. Active implants were built that retained functionality 8 weeks after implantation, and achieved stepping in spinalized rats after just 8-10 days, which is far sooner than wire-based electrical stimulation has achieved in prior work.

Distribuição de tensões em próteses parciais fixas posteriores livres de metal com retentores intracoronários: análise em elementos finitos

Para reabilitar a ausência de um elemento dentário posterior, as próteses parciais fixas (PPF) com retentores intracoronários são uma alternativa aos implantes osseointegrados. O objetivo deste estudo foi avaliar a distribuição de tensões nessas próteses com três combinações de materiais: cerâmica de zircônia parcialmente estabilizada por ítria (ZPEI) revestida por cerâmica de fluorapatita (α), cerâmica de dissilicato de lítio (β) ou compósito fibrorreforçado (γ). Na composição α, foram analisadas a presença ou ausência da cerâmica de revestimento na parede cervical das caixas proximais e três variações na área total da seção transversal dos conectores (4 mm de largura x 3,2, 4,2 ou 5,2 mm de altura). Em 8 modelos bidimensionais de elementos finitos, uma carga vertical de 500 N foi aplicada na fossa central do pôntico e as tensões principais máximas (tração) e mínimas (compressão) foram apontadas em MPa. Inicialmente foram avaliados os 6 modelos com PPF de ZPEI e suas variações. Os maiores valores das tensões de tração foram encontrados no terço cervical dos conectores. Quando presente nestas regiões, a cerâmica de revestimento recebeu tensões acima do limite de sua resistência à flexão. Na comparação entre os modelos sem cerâmica de revestimento na parede cervical das caixas proximais, mesmo aquele com conectores de 3,2 x 4 mm, cuja infraestrutura apresentava 2,5 x 3 mm, poderia ser recomendado para uso clínico. Altos valores de tensões de compressão foram registrados entre o terço oclusal e médio dos conectores, correspondente à união entre as cerâmicas, o que poderia ocasionar, devido à flexão, falhas adesivas. Posteriormente, o modelo de ZPEI com a cerâmica de fluorapatita ausente da parede cervical das caixas proximais e área total dos conectores de 4,2 x 4 mm foi comparado aos dois outros materiais com conectores de mesma área. Na PPF de dissilicato de lítio, os valores representaram uma provável violação do limite de sua resistência à flexão. A PPF de compósito fibrorreforçado apresentou tensões bem abaixo do limite de resistência à flexão de sua infraestrutura, mas, como no modelo de ZPEI, tensões compressivas se concentraram com alto valor entre o terço oclusal e médio dos conectores, local de união entre a resina composta e a infraestrutura de fibras. Os resultados mostraram que a cerâmica de dissilicato de lítio e a presença da cerâmica de fluorapatita na parede cervical das caixas proximais deveriam ser contraindicadas para a condição proposta. Parece viável uma área de conectores na infraestrutura de ZPEI com no mínimo 2,5 x 3 mm. A PPF de compósito fibrorreforçado apresenta resistência estrutural para a situação estudada, mas, como também aquelas compostas de ZPEI, aparenta ter como pontos fracos a adesão entre a infraestrutura e o material de cobertura e a própria resistência deste último.

Dynamics of the East Asian Summer Monsoon in Present and Future Climates

This thesis aims at enhancing our fundamental understanding of the East Asian summer monsoon (EASM), and mechanisms implicated in its climatology in present-day and warmer climates. We focus on the most prominent feature of the EASM, i.e., the so-called Meiyu-Baiu (MB), which is characterized by a well-defined, southwest to northeast elongated quasi-stationary rainfall band, spanning from eastern China to Japan and into the northwestern Pacific Ocean in June and July.

We begin with an observational study of the energetics of the MB front in present-day climate. Analyses of the moist static energy (MSE) budget of the MB front indicate that horizontal advection of moist enthalpy, primarily of dry enthalpy, sustains the front in a region of otherwise negative net energy input into the atmospheric column. A decomposition of the horizontal dry enthalpy advection into mean, transient, and stationary eddy fluxes identifies the longitudinal thermal gradient due to zonal asymmetries and the meridional stationary eddy velocity as the most influential factors determining the pattern of horizontal moist enthalpy advection. Numerical simulations in which the Tibetan Plateau (TP) is either retained or removed show that the TP influences the stationary enthalpy flux, and hence the MB front, primarily by changing the meridional stationary eddy velocity, with reinforced southerly wind on the northwestern flank of the north Pacific subtropical high (NPSH) over the MB region and northerly wind to its north. Changes in the longitudinal thermal gradient are mainly confined to the near downstream of the TP, with the resulting changes in zonal warm air advection having a lesser impact on the rainfall in the extended MB region.

Similar mechanisms are shown to be implicated in present climate simulations in the Couple Model Intercomparison Project - Phase 5 (CMIP5) models. We find that the spatial distribution of the EASM precipitation simulated by different models is highly correlated with the meridional stationary eddy velocity. The correlation becomes more robust when energy fluxes into the atmospheric column are considered, consistent with the observational analyses. The spread in the area-averaged rainfall amount can be partially explained by the spread in the simulated globally-averaged precipitation, with the rest primarily due to the lower-level meridional wind convergence. Clear relationships between precipitation and zonal and meridional eddy velocities are observed.

Finally, the response of the EASM to greenhouse gas forcing is investigated at different time scales in CMIP5 model simulations. The reduction of radiative cooling and the increase in continental surface temperature occur much more rapidly than changes in sea surface temperatures (SSTs). Without changes in SSTs, the rainfall in the monsoon region decreases (increases) over ocean (land) in most models. On longer time scales, as SSTs increase, rainfall changes are opposite. The total response to atmospheric CO^2 forcing and subsequent SST warming is a large (modest) increase in rainfall over ocean (land) in the EASM region. Dynamic changes, in spite of significant contributions from the thermodynamic component, play an important role in setting up the spatial pattern of precipitation changes. Rainfall anomalies over East China are a direct consequence of local land-sea contrast, while changes in the larger-scale oceanic rainfall band are closely associated with the displacement of the larger-scale NPSH. Numerical simulations show that topography and SST patterns play an important role in rainfall changes in the EASM region.

The phytoplankton of an enriched, soft-water lakel subject to intermittent hydraulic flushing (Grasmere, English Lake District)

This paper describes some characteristic features of the phytoplankton of Grasmere, one of the smaller of the principal lakes of the English Lake District, and attempts to relate these to distinctive physical and chemical properties of the lake. Quantitative data presented herein are derived from 5-m vertical column samples, collected with a flexible polyethylene hose close to the deepest point of Grasmere, generally at intervals of 14 days ( 7 days from 1972 to 1978, inclusive). The study concludes that although Grasmere has been subject to increased phosphorus-loading and has quickly developed many features associated with eutrophication, the composition of its plankton has retained the characteristics of a mesotrophic, soft-water lake: a vernal diatom maximum, generally dominated by Asterionella, is followed by summer growths of nanoplanktonic species, of various colonial Chlorophyceae, before a substantial return to Asterionella-dominance in the autumn.

Trapping success and population analysis of Siren lacertina and Amphiuma means

Siren and Amphiuma are two poorly known genera of aquatic salamanders that occur in the Southeastern United States. A primarily bottom-dwelling existence makes these salamanders difficult to detect with conventional sampling methodologies. Therefore, the current status of their populations is unknown. I compared the capture success of modified crayfish traps and plastic minnow traps in capturing these salamanders. In addition, a mark-recapture study of S. lacertina (Greater siren) and A. means (Two-toed amphiuma) was conducted at Okefenokee National Wildlife Refuge (southern Georgia) and at Katharine Ordway Preserve (north-central Florida) from August 2001 until September 2002. Crayfish traps were much more successful than minnow traps in catching siren and amphiuma. Crayfish traps yielded 270 captures for an overall capture success of 16%, whereas minnow traps yielded only 13 captures for an overall success rate of 0.05%. In addition, several marking techniques were evaluated, and of these, only passive integrated transponder (PIT) tags were retained for the duration of the study. Therefore, I recommend this marking technique for long-term monitoring of S. lacertina and A. means. Several variables were found to have significant effects on capture rates of salamanders. A. means were most often captured in summer and the number of captures was positively correlated with water temperature, water level, and rainfall. S. lacertina were most often captured during winter and spring. Number of captures was negatively correlated with water temperature, while no relationship was found with water level or rainfall. Trap day and baiting had no significant effect on number of A. means or S. lacertina captured. Recapture probabilities of both species were low, 0.025-0.03 for S. lacertina and 0.08-0.11 for A. means. Monthly survival rates were high, 0.77-0.97 for A. means and 0.88-1.00 for S. lacertina. Density estimates of 1.3 salamanders/m2 (S. lacertina) and 0.28 salamanders/m2 (A. means) were obtained for Lake Suggs using Jolly-Seber models. Siren and amphiuma make up a substantial part of wetland biomass and can impact many other wetland species. Thus, more attention must be focused on evaluating and monitoring their populations.

A Delphi Process to Optimize Quality and Performance of Drug Evaluation in Neonates

Background: Neonatal trials remain difficult to conduct for several reasons: in particular the need for study sites to have an existing infrastructure in place, with trained investigators and validated quality procedures to ensure good clinical, laboratory practices and a respect for high ethical standards. The objective of this work was to identify the major criteria considered necessary for selecting neonatal intensive care units that are able to perform drug evaluations competently. Methodology and Main Findings: This Delphi process was conducted with an international multidisciplinary panel of 25 experts from 13 countries, selected to be part of two committees (a scientific committee and an expert committee), in order to validate criteria required to perform drug evaluation in neonates. Eighty six items were initially selected and classified under 7 headings: "NICUs description - Level of care'' (21), "Ability to perform drug trials: NICU organization and processes (15), "Research Experience'' (12), "Scientific competencies and area of expertise'' (8), "Quality Management'' (16), "Training and educational capacity'' (8) and "Public involvement'' (6). Sixty-one items were retained and headings were rearranged after the first round, 34 were selected after the second round. A third round was required to validate 13 additional items. The final set includes 47 items divided under 5 headings. Conclusion: A set of 47 relevant criteria will help to NICUs that want to implement, conduct or participate in drug trials within a neonatal network identify important issues to be aware of. Summary Points: 1) Neonatal trials remain difficult to conduct for several reasons: in particular the need for study sites to have an existing infrastructure in place, with trained investigators and validated quality procedures to ensure good clinical, laboratory practices and a respect for high ethical standards. 2) The present Delphi study was conducted with an international multidisciplinary panel of 25 experts from 13 countries and aims to identify the major criteria considered necessary for selecting neonatal intensive care units (NICUs) that are able to perform drug evaluations competently. 3) Of the 86 items initially selected and classified under 7 headings - "NICUs description - Level of care'' (21), "Ability to perform drug trials: NICU organization and processes (15), "Research Experience'' (12), "Scientific competencies and area of expertise'' (8), "Quality Management'' (16), "Training and educational capacity'' (8) and "Public involvement'' (6) - 47 items were selected following a three rounds Delphi process. 4) The present consensus will help NICUs to implement, conduct or participate in drug trials within a neonatal network.

Investigação de mutações no gene ATP13A2 como um fator de risco para a Doença de Parkinson em pacientes brasileiros

A doença de Parkinson (DP) é a desordem neurodegenerativa motora mais frequente, com uma prevalência de, aproximadamente, 1% entre indivíduos com mais de 60 anos de idade, aumentando para 4 a 5% entre os indivíduos com idade superior a 85 anos. Esta condição é caracterizada pela perda seletiva dos neurônios dopaminérgicos da substância negra e pela presença de inclusões protéicas ricas em α-sinucleína nos neurônios sobreviventes. Pouco se sabe sobre a etiologia e a patogênese da DP. A maioria dos casos aparece esporadicamente, podendo estar associados a diversos fatores de risco ambientais e genéticos. Na última década, estudos de ligação identificaram 15 loci cromossômicos (PARK1 a PARK15) relacionados à DP e, nestes, um novo gene, ATP13A2, tem sido associado a casos de DP de início precoce. Esse gene está situado no 1p36 e codifica a proteína ATPase tipo-P da subfamília P5, de localização lisossômica, que é expressa em diversos tecidos, principalmente no cérebro. Mutações em ATP13A2 levam à formação de proteínas truncadas que ficam retidas no reticulo endoplasmático e posteriormente são degradadas pelo proteossomo, podendo causar a disfunção proteossômica, decorrente da sobrecarga gerada pela proteína mutante, ou causar a disfunção lisossômica, ambas gerando agregação tóxica. Este trabalho tem como objetivo realizar a análise molecular do gene ATP13A2 em uma amostra de 116 pacientes brasileiros com DP, de manifestação precoce (<50 anos), de forma a avaliar se mutações neste gene representam um fator de risco para a DP. O DNA foi extraído a partir de leucócitos do sangue periférico ou de saliva e a análise molecular dos éxons 2, 3, 12, 13, 14, 15, 16, 26 e 27, bem como, dos limites íntronéxons foi realizada por sequenciamento automático dos produtos da PCR. Identificamos oito variantes de sequência: quatro variantes intrônicas (uma no íntron 2, uma no íntron 13 e duas no íntron 27) e quatro variantes silenciosas (uma no éxon 3, 16, 26 e 27). Com base em dados da literatura e através de análises in silico e comparação com amostras controle, classificamos a alteração intrônica c.3084- 3C>T, e as alterações silenciosas c.2970G>A e c.3192C>T como não patogênicas; as alterações intrônicas c.106-30G>T, c.1306+42_1306+43 insC e c.3083+24C>T, e as alterações silenciosas c.132A>G e c.1610G>T foram classificadas como provavelmente não patogênicas. Nosso achados corroboram àqueles encontrados em outras populações e indicam que mutações no gene ATP13A2 não são uma causa comum de DP na amostra de pacientes brasileiros analisados. No entanto, se faz necessário estender nossas análises para outras regiões gênicas, a fim de determinar o real papel deste gene na etiologia da DP em nossa população.

Avaliação da concentração de Cl, K e Ca na urina, hemolinfa e túbulos de Malpighi de Rhodnius prolixus usando a técnica de fluorescência de raios X por reflexão total por radiação síncrotron (SR-TXRF)

Neste trabalho utilizou-se a técnica fluorescência de raios X usando radiação síncrotron (SR-TXRF) para estudar, quantitativamente, o transporte de cloro, potássio e cálcio na hemolinfa, urina e túbulos de Malpighi (TM) em ninfas de quinto estágio do Rhodnius prolixus (R. prolixus), considerando a excreção destes elementos em diferentes dias após o repasto sanguíneo. R. prolixus é um dos principais vetores do Trypanosoma cruzi, agente causador da doença de Chagas. R. prolixus fornece um sistema modelo particularmente útil porque seus TMs tanto secretam quanto reabsorvem íons a taxas elevadas. Os TMs filtram a hemolinfa e secretam um líquido que é muitas vezes comparado com a urina primária em vertebrados. Os resultados obtidos mostram que a concentração de potássio na urina é substancialmente maior do que na hemolinfa. A concentração de cloro na hemolinfa é menor do que na urina, mas a diferença não é tão marcada como no caso do potássio. No caso do Rhodnius é razoável interpretar a elevada concentração de potássio na urina como adaptativo para o problema de excreção imediato do inseto. A concentração de cálcio nos TMs é substancialmente maior em comparação com os valores encontrados na hemolinfa e urina. Este resultado mostra que o cálcio é retido no corpo do R. prolixus e pouco eliminado. Os resultados obtidos estão coerentes com a literatura. Avaliou-se também o efeito no transporte de Cl, K e Ca após um repasto de sangue de coelho contaminado com HgCl2 de modo a avaliar o efeito da presença deste metal tóxico no balanço iônico nos fluidos de excreção urina e hemolinfa e também pelo principal órgão de transporte, os túbulos de Malpighi. As excreções de Cl e K pela urina são afetadas pela ingestão. Este resultado é esperado levando-se em consideração a ingestão de excesso de Cl através do HgCl2. O transporte de Cl, K e Ca na hemolinfa do Rhodnius prolixus não é afetada pela ingestão de HgCl2. Nos túbulos de Malpighi, as altas concentrações de Ca obtidas foram comparáveis àquelas encontradas nos insetos controle. Pode-se concluir que SR-TXRF é um método muito promissor para análises diretas, rápidas e confiáveis para a quantificação simultânea de elementos envolvidos na regulação do transporte e em todo o sistema excretor de insetos. Além disso, o estudo do transporte e a excreção de elementos no inseto Rhodnius prolixus abrem oportunidade para a maior compreensão de efeitos da poluição em espécies de invertebrados.

Incidência de tuberculose por município, Brasil 2001-2003: uma abordagem sobre o programa de controle e fatores determinantes da doença

Esta pesquisa avaliou a situação da tuberculose no Brasil, no período de 2001 a 2003, segundo indicadores do processo de operacionalização do Programa Nacional de Controle de Tuberculose (PNCT), e estimou os efeitos de fatores determinantes da taxa de incidência da doença. Para a avaliação utilizou-se a análise de cluster não-hierárquica, visando agrupar os municípios brasileiros de acordo com a morbidade por tuberculose (TB) e AIDS, e pelo desempenho do PNCT. Estes clusters foram mapeados, comparando-se a distribuição nos municípios, em regiões metropolitanas, municípios prioritários, e segundo o tamanho da população. O qui-quadrado de Pearson foi utilizado para testar associação nas categorias. A modelagem longitudinal multinível foi usada para identificar e estimar os efeitos dos determinantes da doença. Os agregados foram: anos, municípios e regiões metropolitanas. O modelo foi de intercepto e inclinação aleatória. Foram retidas as variáveis capazes de diminuir a variância dos níveis, pois, desta forma, explicam a variabilidade hierárquica da doença. Incluiu-se renda, densidade populacional, proporção de cura, taxa de incidência de AIDS e as grandes regiões brasileiras. A avaliação mostrou que a situação epidemiológica preocupante ocorreu nos municípios com Baixa TB e Alta AIDS, e Alta TB e AIDS. O cluster de Muito baixa TB e AIDS concentrou 50% dos municípios, o que pode configurar problemas de notificação. São 6 clusters de desempenho do programa. Bom e Bom com baixo DOTS predominando nos municípios pequenos, não prioritários e fora das regiões metropolitanas. No desempenho Moderado houve maior proporção de municípios prioritários. Clusters Regular e Fraco concentraram 10% dos municípios, com abandono de tratamento elevado e cura muito baixa. O cluster Muito Fraco caracterizou-se pela falta de dados nos indicadores de desempenho. O modelo multinível identificou a AIDS como fator impactante na tuberculose, anteriormente não encontrado em outros estudos; a interação entre renda e AIDS, e importante contribuição das regiões metropolitanas na distribuição da tuberculose, que se manifesta heterogeneamente nas grandes regiões do país. A análise discriminou municípios, e mostrou não haver associação entre maior morbidade e melhor desempenho do PNCT, retratando inadequação da vigilância à realidade epidemiológica do Brasil. O programa necessita ser reforçado, no sentido de considerar a AIDS ao estabelecer suas estratégias de controle. Ademais, os aspectos de baixa renda da população e densidade populacional, já analisados em diversas pesquisas, também se manifestaram de forma importante nestes resultados.

Alcohol-Related Brain Damage in Humans

Chronic excessive alcohol intoxications evoke cumulative damage to tissues and organs. We examined prefrontal cortex (Brodmann's area (BA) 9) from 20 human alcoholics and 20 age, gender, and postmortem delay matched control subjects. H & E staining and light microscopy of prefrontal cortex tissue revealed a reduction in the levels of cytoskeleton surrounding the nuclei of cortical and subcortical neurons, and a disruption of subcortical neuron patterning in alcoholic subjects. BA 9 tissue homogenisation and one dimensional polyacrylamide gel electrophoresis (PAGE) proteomics of cytosolic proteins identified dramatic reductions in the protein levels of spectrin beta II, and alpha- and beta-tubulins in alcoholics, and these were validated and quantitated by Western blotting. We detected a significant increase in a-tubulin acetylation in alcoholics, a non-significant increase in isoaspartate protein damage, but a significant increase in protein isoaspartyl methyltransferase protein levels, the enzyme that triggers isoaspartate damage repair in vivo. There was also a significant reduction in proteasome activity in alcoholics. One dimensional PAGE of membrane-enriched fractions detected a reduction in beta-spectrin protein levels, and a significant increase in transmembranous alpha 3 (catalytic) subunit of the Na+, K+-ATPase in alcoholic subjects. However, control subjects retained stable oligomeric forms of a-subunit that were diminished in alcoholics. In alcoholics, significant loss of cytosolic alpha-and beta-tubulins were also seen in caudate nucleus, hippocampus and cerebellum, but to different levels, indicative of brain regional susceptibility to alcohol-related damage. Collectively, these protein changes provide a molecular basis for some of the neuronal and behavioural abnormalities attributed to alcoholics

Copépodes pélagiques du plateau ivoirien. 2 - Utilisation de l'arbre de longueur minimum dans le classement des récoltes

The minimum spanning tree algorithm is used to classify two sets of planktonic copepod samples. This algorithm links the samples the distance of which is minimum, without doing a loop, so that the sum of the segment lengths is minimum. The authors estimated the distance between samples by 2 different ways: by a coefficient of association the Jaccard's index - and by the x2 distance. Jaccard's index is not retained but the use of the x2 distance allows comparison with the 'analyse factorielle des correspondances'. The results are discussed from an ecological point of view.