Influence of Composition and Structure on the Optoelectronic Properties of Photocatalytic Bi4NbO8Cl-Bi2GdO4Cl Intergrowths.

Mixed metal oxyhalides are an exciting class of photocatalysts, capable of the sustainable generation of fuels and remediation of pollutants with solar energy. Bismuth oxyhalides of the types Bi4MO8X (M = Nb and Ta; X = Cl and Br) and Bi2AO4X (A = most lanthanides; X = Cl, Br, and I) have an electronic structure that imparts photostability, as their valence band maxima (VBM) are composed of O 2p orbitals rather than X np orbitals that typify many other bismuth oxyhalides. Here, flux-based synthesis of intergrowth Bi4NbO8Cl-Bi2GdO4Cl is reported, testing the hypothesis that both intergrowth stoichiometry and M identity serve as levers toward tunable optoelectronic properties. X-ray scattering and atomically resolved electron microscopy verify intergrowth formation. Facile manipulation of the Bi4NbO8Cl-to-Bi2GdO4Cl ratio is achieved with the specific ratio influencing both the crystal and electronic structures of the intergrowths. This compositional flexibility and crystal structure engineering can be leveraged for photocatalytic applications, with comparisons to the previously reported Bi4TaO8Cl-Bi2GdO4Cl intergrowth revealing how subtle structural and compositional features can impact photocatalytic materials.

Metallicity and chemical bonding in anti-anatase Mo2N.

Here we present a detailed analysis of the structure, bonding character, and electronic structure of anti-anatase ß-Mo2N using density functional theory calculations. We analyze the crystal orbital Hamilton populations, phonon band structure, and electronic structure calculations to explain its low energy transport behavior. We further examine the electronic structures of (anti-)rutile and (anti-)anatase M3-nXn (X = N,O; n = 1,2) M = Ti and Mo nitrides and oxides to show that the atomic structure of anti-anatase leads to metallic behavior independent of the metal and ligand chemistry. Finally, we assess whether these anti-anatase compounds are viable electrides using electron density maps and electron localization functions. Our work shows anti-structures of known binary compounds can expand the phase space of available metallic ceramics beyond layered, hexagonal carbides and nitrides, e.g., Mn+1An (MAX) where n = 1-4.

Low Thermal Conductivity in Heteroanionic Materials with Layers of Homoleptic Polyhedra.

Although BiAgOSe, an analogue of a well-studied thermoelectric material BiCuOSe, is thermodynamically stable, its synthesis is complicated by the low driving force of formation from the stable binary and ternary intermediates. Here we have developed a "subtraction strategy" to suppress byproducts and produce pure phase BiAgOSe using hydrothermal methods. Electronic structure calculations and optical characterization show that BiAgOSe is an indirect bandgap semiconductor with a bandgap of 0.95 eV. The prepared sample exhibits lower lattice thermal conductivities (0.61 W·m-1·K-1 at room temperature and 0.35 W·m-1·K-1 at 650 K) than BiCuOSe. Lattice dynamical simulations and variable temperature diffraction measurements demonstrate that the low lattice thermal conductivity arises from both the low sound velocity and high phonon-phonon scattering rates in BiAgOSe. These in turn result primarily from the soft Ag-Se bonds in the edge-sharing AgSe4 tetrahedra and large sublattice mismatch between the quasi-two-dimensional [Bi2O2]2+ and [Ag2Se2]2- layers. These results highlight the advantages of manipulating the chemistry of homoleptic polyhedra in heteroanionic compounds for electronic structure and phonon transport control.

Ultrafast Suppression of the Ferroelectric Instability in KTaO_{3}.

We use an x-ray free-electron laser to study the lattice dynamics following photoexcitation with ultrafast near-UV light (wavelength 266 nm, 50 fs pulse duration) of the incipient ferroelectric potassium tantalate, KTaO_{3}. By probing the lattice dynamics corresponding to multiple Brillouin zones through the x-ray diffuse scattering with pulses from the Linac Coherent Light Source (LCLS) (wavelength 1.3 Å and <10 fs pulse duration), we observe changes in the diffuse intensity associated with a hardening of the transverse acoustic phonon branches along Γ to X and Γ to M. Using force constants from density functional theory, we fit the quasiequilibrium intensity and obtain the instantaneous lattice temperature and density of photoexcited charge carriers. The density functional theory calculations demonstrate that photoexcitation transfers charge from oxygen 2p derived π-bonding orbitals to Ta 5d derived antibonding orbitals, further suppressing the ferroelectric instability and increasing the stability of the cubic, paraelectric structure.

Strain-Induced Magnetic Transitions in SrMO2.5 (M = Mn, Fe) Thin Films with Ordered Oxygen Vacancies.

We examine the epitaxial-strain-induced phase transitions in thin films of perovskite-derived SrMnO2.5 and SrFeO2.5 exhibiting ordered oxygen vacancies (OOVs). We find that SrMnO2.5 hosts multiple magnetic transitions to other ordered states, including antiferromagnetic (AFM) and ferromagnetic (FM) orders of E*-AFM, C-AFM, and FM types depending on the compressive or tensile strain state. In contrast, no magnetic transitions occur in thin-film SrFeO2.5 (G-AFM to FM), whereas its bulk phase exhibits a hydrostatic pressure-induced AFM-to-FM transition. We explain the origin of these dependencies on the transition-metal configuration, that is, d4 Mn versus d5 Fe, and the relative orientation of the OOVs in the Ca2Mn2O5-type structure with respect to the epitaxial interface. We find that the magnetic phase stability can be predicted by using exchange striction arguments, with FM (AFM) spin interactions preferring longer (shorter) Mn-O bonds in the square pyramidal MnO5 unit comprising SrMnO2.5. Because the Mn-O bond lengths directly shrink or elongate to accommodate the applied stress without considerable polyhedral rotations, we show that compressive and tensile strain tune the unit cell structure to favor different combinations of exchange interactions that stabilize the various magnetic spin orders. Our study shows that the strong coupling between the OOV structure and spin orders with epitaxial strain is a promising route to achieve picoscale control of functional electronic and magnetic responses in complex oxide thin films.

Pressure-Induced Collapse of Magnetic Order in Jarosite.

We report a pressure-induced phase transition in the frustrated kagomé material jarosite at ∼45 GPa, which leads to the disappearance of magnetic order. Using a suite of experimental techniques, we characterize the structural, electronic, and magnetic changes in jarosite through this phase transition. Synchrotron powder x-ray diffraction and Fourier transform infrared spectroscopy experiments, analyzed in aggregate with the results from density functional theory calculations, indicate that the material changes from a R3[over ¯]m structure to a structure with a R3[over ¯]c space group. The resulting phase features a rare twisted kagomé lattice in which the integrity of the equilateral Fe^{3+} triangles persists. Based on symmetry arguments we hypothesize that the resulting structural changes alter the magnetic interactions to favor a possible quantum paramagnetic phase at high pressure.

Mixed-Metal Carbonate Fluorides as Deep-Ultraviolet Nonlinear Optical Materials.

Noncentrosymmetric mixed-metal carbonate fluorides are promising materials for deep-ultraviolet (DUV) nonlinear optical (NLO) applications. We report on the synthesis, characterization, structure-property relationships, and electronic structure calculations on two new DUV NLO materials: KMgCO3F and Cs9Mg6(CO3)8F5. Both materials are noncentrosymmetric (NCS). KMgCO3F crystallizes in the achiral and nonpolar NCS space group P6̅2m, whereas Cs9Mg6(CO3)8F5 is found in the polar space group Pmn21. The compounds have three-dimensional structures built up from corner-shared magnesium oxyfluoride and magnesium oxide octahedra. KMgCO3F (Cs9Mg6(CO3)8F5) exhibits second-order harmonic generation (SHG) at both 1064 and 532 nm incident radiation with efficiencies of 120 (20) × α-SiO2 and 0.33 (0.10) × ß-BaB2O4, respectively. In addition, short absorption edges of <200 and 208 nm for KMgCO3F and Cs9Mg6(CO3)8F5, respectively, are observed. We compute the electron localization function and density of states of these two compounds using first-principles density functional theory, and show that the different NLO responses arise from differences in the denticity and alignment of the anionic carbonate units. Finally, an examination of the known SHG active AMCO3F (A = alkali metal, M = alkaline earth metal, Zn, Cd, or Pb) materials indicates that, on average, smaller A cations and larger M cations result in increased SHG efficiencies.

Inversion symmetry breaking by oxygen octahedral rotations in the Ruddlesden-Popper NaRTiO4 family.

Rotations of oxygen octahedra are ubiquitous, but they cannot break inversion symmetry in simple perovskites. However, in a layered oxide structure, this is possible, as we demonstrate here in A-site ordered Ruddlesden-Popper NaRTiO4 (R denotes rare-earth metal), previously believed to be centric. By revisiting this series via synchrotron x-ray diffraction, optical second-harmonic generation, piezoresponse force microscopy, and first-principles phonon calculations, we find that the low-temperature phase belongs to the acentric space group P42(1)m, which is piezoelectric and nonpolar. The mechanism underlying this large new family of acentric layered oxides is prevalent, and could lead to many more families of acentric oxides.

Vitamin C further improves the protective effect of GLP-1 on the ischemia-reperfusion-like effect induced by hyperglycemia post-hypoglycemia in type 1 diabetes.

BACKGROUND: It has been reported that hyperglycemia following hypoglycemia produces an ischemia-reperfusion-like effect in type 1 diabetes. In this study the possibility that GLP-1 has a protective effect on this phenomenon has been tested. METHODS: 15 type 1 diabetic patients underwent to five experiments: a period of two hours of hypoglycemia followed by two hours of normo-glycemia or hyperglycemia with the concomitant infusion of GLP-1 or vitamin C or both. At baseline, after 2 and 4 hours, glycemia, plasma nitrotyrosine, plasma 8-iso prostaglandin F2alpha, sCAM-1a, IL-6 and flow mediated vasodilation were measured. RESULTS: After 2 h of hypoglycemia, flow mediated vasodilation significantly decreased, while sICAM-1, 8-iso-PGF2a, nitrotyrosine and IL-6 significantly increased. While recovering with normoglycemia was accompanied by a significant improvement of endothelial dysfunction, oxidative stress and inflammation, a period of hyperglycemia after hypoglycemia worsens all these parameters. These effects were counterbalanced by GLP-1 and better by vitamin C, while the simultaneous infusion of both almost completely abolished the effect of hyperglycemia post hypoglycemia. CONCLUSIONS: This study shows that GLP-1 infusion, during induced hyperglycemia post hypoglycemia, reduces the generation of oxidative stress and inflammation, improving the endothelial dysfunction, in type 1 diabetes. Furthermore, the data support that vitamin C and GLP-1 may have an additive protective effect in such condition.

Control of tubulin gene expression during metacyclogenesis of Trypanosoma cruzi.

During differentiation of the dividing epimastigote to the non-dividing metacyclic trypomastigote form of the parasitic protozoan Trypanosoma cruzi there is a marked reduction in the rate of synthesis of the major proteins alpha- and beta-tubulin. Our results indicate that the control of synthesis of these proteins during the differentiation event is exerted at the level of alpha- and beta-tubulin mRNA accumulation.

Linear optical and electronic properties of the polar metallic ruthenate (Sr,Ca)Ru2O6.

Using first-principles calculations, we compute the linear optical properties for cation ordered (Sr,Ca)Ru2O6. Our calculations show that this polar ferromagnetic metallic oxide exhibits optical anisotropy along the principal directions of the optical indicatrix owing to the absence of inversion symmetry in the crystal structure. The calculated reflectivity is used to locate the onset of the inter-band transitions at an energy of 1.3 eV. Comparing the optical conductivity with the electronic band structure, we identify the possible optical transitions. Finally, we apply the generalized Drude model to deduce an enhancement of the effective mass, m(*) ∼ 4.9m(e), in ordered (Sr,Ca)Ru2O6. Moreover, we show that removal of the polar distortions decrease the effective mass to m(*) ∼ 4.4m(e), suggesting that control over the amplitude of the polar displacements could be used to tune the degree of electronic correlation in oxide conductors without inversion symmetry.

Electronically driven structural transitions in A10(PO4)6F2 apatites (A = Ca, Sr, Pb, Cd and Hg).

It is shown that there is a dynamic lattice instability in the aristotype P63/m structure of A10(PO4)6F2 apatites containing divalent A-site Cd or Hg cations with (n - 1)d(10)ns(0) electronic configurations. The distortion to a low-symmetry P\bar{1} triclinic structure is driven by an electronic mechanism rather than from ionic size mismatch. Our theoretical work provides key insights into the role of the electronic configurations of A cations in fluorapatites.

Carcinoma de mama bilateral sincrônico com diferentes comportamentos biológicos: relato de caso / Synchronous bilateral breast carcinoma with different biological behaviors: case report

De ne-se carcinoma de mama bilateral sincrônico (CMBS) pelo diagnóstico de dois tumores primários simultâneos. Relata-se o caso de uma paciente do sexo feminino, 55 anos, caucasiana, que procurou o mastologista por uma lesão na mama direita (MD). Ao exame físico na MD, notou-se um abaulamento no quadrante superior externo (QSE), retração e ulceração de pele e palpou-se massa de 5 cm no QSE, endurecida, irregular, com expressão mamilar negativa e linfonodo axilar suspeito e com estádio clínico III (T4b N1 Mx). A mama esquerda (ME) apre- sentou-se normal. A mamogra a mostrou nódulo suspeito no QSE da MD (BI-RADS V) e ME com calci cações monomór cas (BI-RADS II). A ressonância magnética revelou nódulo sólido, heterogêneo (3 cm) no QSE da MD (BI-RADS V) e também nódulo sólido, irregular (7 mm) no quadrante inferior externo (QIE) da ME (BI-RADS V). Os demais exames não demonstraram metástases. A biópsia revelou carcinoma ductal invasivo (CDI) na MD e carcinoma ductal in situ na ME, compatível com CMBS. Na ME, a imuno-histoquímica demonstrou receptores de estrogênio e progesterona positivos, CERB-B2 negativos e Ki-67 com expressão nuclear positiva em 5% das células neoplásicas. Na MD, receptores triplo-negativos e Ki-67 positivo em 10%. Após quimioterapia neoadjuvante, a paciente foi submetida a mastectomia direita com linfade- nectomia axilar e quadrantectomia esquerda com linfonodo sentinela. O anatomopatológico da MD evidenciou carcinoma ductal invasor residual, margens cirúrgicas e linfonodos livres. Na ME, linfonodo sentinela livre e resposta patológica completa. Prosseguiu-se o tratamento com radioterapia e Tamoxifeno. Atualmente, a literatura médica sobre o CMBS é escassa, di cul- tando o manejo terapêutico nos casos em que cada tumor exibe características biológicas diferentes.

Bilateral synchronous breast carcinoma (BSBC) is de ned by the simultaneous presence of two prima- ry tumors at diagnosis. is is a case report of a female patient, aged 55 years, Caucasian, who sought a mastology service because of a lesion in the right breast (RB). In physical examination, a lump in the RB was noticed in the superolateral quadrant (SLQ), as well as retraction and skin ulceration, with a palpable irregular mass of 5 cm, without nipple discharge, abnormal axillary lymph node, and stage III (T4b N1 Mx). Left breast (LB) was normal. Mammography showed suspicious lump in SLQ of RB (BI-RADS V), LB with monomorphic calci cations (BI-RADS II). MRI revealed a solid heteroge- neous nodule (3 cm) in SLQ of RB (BI-RADS V) and an irregular solid nodule (7 mm) in inferolateral quadrant (ILQ) of LB (BI-RADS V). Metastasis was not found on other tests. Biopsy revealed invasive ductal carcinoma in RB and ductal carcinoma in situ in LB, compatible with BSBC. On LB, the immu- nohistochemistry showed positive estrogen and progesterone receptors, negative for CERB-B2 and Ki-67 positive nuclear expression in 5% of tumor cells. RB presented triple-negative receptors and Ki-67 posi- tive in 10%. After neoadjuvant chemotherapy, a right mastectomy with axillary lymphadenectomy and left quadrantectomy with sentinel lymph node was performed. Anatomopathological exam of RB showed residual ductal carcinoma, free surgical margins and lymph nodes. In LB, sentinel lymph node was disease free and there was a complete pathological response. Treatment was continued with radiotherapy and Tamoxifen. Currently, the medical literature on the BSBC is scarce, thus hampering the therapeutic management in cases where each tumor displays di erent biological characteristics.

Molecular conversion of muscarinic acetylcholine receptor M(5) to muscarinic toxin 7 (MT7)-binding protein.

Muscarinic toxin 7 (MT7) is a mamba venom peptide that binds selectively to the M(1) muscarinic acetylcholine receptor. We have previously shown that the second (ECL2) and third (ECL3) extracellular loops of the M(1) receptor are critically involved in binding the peptide. In this study we used a mutagenesis approach on the M(5) subtype of the receptor family to find out if this possesses a similar structural architecture in terms of toxin binding as the M(1) receptor. An M(5) receptor construct (M(5)-E(175)Y(184)E(474)), mutated at the formerly deciphered critical residues on ECL2 and 3, gained the ability to bind MT7, but with rather low affinity as determined in a functional assay (apparent K(i) = 24 nM; apparent K(i) for M(1) = 0.5 nM). After screening for different domains and residues, we found a specific residue (P(179) to L in M(5)) in the middle portion of ECL2 that was necessary for high affinity binding of MT7 (M(5)-EL(179)YE, apparent K(i) = 0.5 nM). Mutation of P(179) to A confirmed a role for the leucine side chain in the binding of MT7. Together the results reveal new binding interactions between receptors and the MT7 peptide and strengthen the hypothesis that ECL2 sequence is of utmost importance for MT binding to muscarinic receptors.

Latent tuberculosis infection in a migrant agricultural community in Baja California, Mexico.

The objectives were to estimate the prevalence and identify correlates of latent tuberculosis infection (LTBI) among residents of a migrant agricultural community in San Quintín, Baja-California, Mexico. Residents completed a questionnaire and had their blood tested for LTBI using the QuantiFERON(®)-TB Gold In-Tube (QFT) assay. Among 133 participants, 39.8% (95% CI 31.5-48.7%) tested QFT-positive. Having crossed the U.S.-Mexican border since living in San Quintin (P = 0.03), consuming unpasteurized milk (P = 0.02) and receiving health care at IMSS-Oportunidades in the last 6 months (P = 0.03) were independently associated with QFT-positivity. High LTBI prevalence in this community emphasizes the need for TB education and LTBI treatment for its residents. Association with travel to the U.S. suggests the potential for TB transmission across borders. Higher QFT-positivity among those consuming unpasteurized milk could indicate M. bovis infection, previously reported among Mexican migrants living in U.S. border cities.

Androgen-receptor gene structure and function in prostate cancer.

Androgen-receptor (AR) gene mutations have been found in clinical prostate cancer, both prior to hormonal therapy and in hormone-refractory disease that persists despite androgen-ablative therapy. Thus, mutations that are present in late-stage disease might arise prior to therapy rather than as a result of therapy. A common feature of mutations in untreated prostate cancer and in hormone-refractory prostate cancer is that the AR retains activity as a ligand-dependent transcription factor. Some AR mutations in prostate cancer show broadened ligand specificity, such that the transcription-factor activity of the AR can be stimulated not just by dihydrotestosterone (DHT) but also by estradiol and other androgen metabolites that have a low affinity for the AR. The activation of mutant AR by estrogen and weak androgens could confer on prostate cancer cells an ability to survive testicular androgen ablation by allowing activation of the AR by adrenal androgens or exogenous estrogen. Such mutations might confer an advantage even prior to androgen ablation, since prostate cancer has lower levels of 5 alpha-reductase and, therefore, of DHT, than normal. Thus, AR mutations that occur prior to therapy may characterize a more aggressive disease. A large percentage of tumors appear to have no AR gene mutation. In tumors without an AR gene mutation, AR function might be affected via other mechanisms (e.g., AR gene amplification, which could increase the amount of AR activity at a given DHT level). Importantly, the apparent absence of AR gene mutations in the majority of earlystage tumors indicates that the role of androgen in the development of clinical prostate cancer is mediated predominantly by a normal AR gene. There are actually multiple alleles of the normal AR gene; these allelic variants differ in glutamine and glycine repeat length in the transactivation domain of the protein, and they may differ in signal-transducing activity. The glutamine and glycine repeat length may thereby modulate the effect of androgen on tumor-cell proliferation that occurs during clonal expansion.

Protein biosynthesis changes in Trypanosoma cruzi induced by supra-optimal temperature.

Early during vertebrate infection, T. cruzi is exposed to the host blood at an elevated temperature. Bearing this in mind, the pattern of protein synthesis of two parasite forms was examined. SDS-PAGE of heated organisms showed an increase in at least four proteins (103, 92, 75 and 61 kD). The temperature effect is also manifested in cells whose RNA synthesis is reduced by actinomycin D treatment. The synthesis of the '29 degrees proteins' is inhibited at 40 degrees C in organisms growing in culture medium; when the organisms were maintained in serum, the inhibition was not observed. The inhibitory effect observed at 40 degrees C was reversed when the temperature was shifted to 29 degrees C. These proteins were synthesized for 180 min at 37 degrees C or 360 min at 40 degrees C. The increased protein synthesis manifested at 37 degrees C had decreased 45 min after the temperature was lowered to 29 degrees C. When the cells were pre-incubated at 40 degrees C and shifted to 29 degrees C, the synthesis of the heat-induced proteins proceeded for at least 180 min. This pattern of heat induction in epimastigotes and trypomastigotes is the same irrespective of whether the incubation medium is LIT (for epimastigotes), M-16 (for trypomastigotes), or when serum was used for both cell types.

Heat shock proteins in Trypanosoma cruzi: identification and localization of HSP70 and HSP60 proteins and structure of HSP60 genes (brief report).

To identify the members of the HSP70 and HSP60 families of Trypanosoma cruzi, we analysed 35S methionine epimastigote cells by two dimensional Western blot. At 29 degrees C, an HSP70 monoclonal antibody (anti-D. melanogaster) recognized eight isotypes. At least five of these were heat-induced. Polyclonal antibody against the 65 KDa antigen (anti-M. tuberculosis) recognized three isotypes with identical molecular weights, but different microliters. Only one isoform was heat induced. The cellular distribution of HSP70 and HSP60 was studied by immunoelectron microscopy. Anti-HSP70 reactive protein was localized in the cytoplasm, mitochondria and nucleus, while anti-HSP60 protein was found in the mitochondrion and in close association with the kinetoplast. To characterize the HSP60 gene and its proteins, we isolated a genomic T. cruzi clone encoding the HSP60 gene. T. cruzi HSP60 genes could be shown to be organized in 2100 nt tandem arrays. RELP in the HSP60 genes revealed that at least three different types of HSP60 genes were encoded in the T cruzi genome. The predicted open reading frame measured exhibits about 50% identity to other HSP60 described. Expression of these HSP60 genes could not be induced by 2 hours heat shock at 37 degrees C. Post-transcriptional mechanisms may be responsible for HSP60 induction in T. cruzi.

Polimorfismo do gene da enzima conversora de angiotensina e avaliação cardiovascular em adultos com deficiência do hormônio do crescimento / Angiotensin converting enzyme gene polymorphisms and cardiovascular evaluation in growth hormone deficient adults

Fundamentos: A enzima conversora da angiotensina (ECA) é importante reguladora da pressão arterial (PA). Polimorfismos no gene da ECA estão associados a alterações na PA. Não existem ainda estudos sobre areposição de hormônio do crescimento (GH) em adultos com deficiência do hormônio do crescimento (DGH) deacordo com os genótipos da ECA.Objetivo: Avaliar a resposta cardiovascular ao GH em adultos com DGH de acordo com o seu genótipo da ECA. Métodos: Avaliados 18 pacientes com hipopituitarismo de acordo com o genótipo da ECA no basal e 24 mesesapós reposição com GH de acordo com parâmetros clínicos e cardiovasculares.Resultados: Dez mulheres e 8 homens foram avaliados (média de idade 44,9±10,9 anos). Distribuição genotípicaencontrada: genótipo DD: 7 (38,9%) pacientes; genótipo ID: 11 (61,1%) pacientes. Frequência cardíaca, PA sistólica e diastólica, carga pressórica sistólica e diastólica, e funções sistólica e diastólica foram normais em todos ospacientes. Na avaliação basal, pacientes com genótipo DD demonstraram níveis de PA sistólica, diastólica diurna e nas 24 horas mais altos (p<0,05); carga pressórica diastólica maior (p<0,05). Comparando-se os dois genótipos ao final do estudo, os pacientes com genótipo DD evidenciaram: redução estatisticamente significativa da pressão diastólica diurna e nas 24 horas, da carga pressórica sistólica e diastólica diurna e nas 24 horas; e aumento da frequência cardíaca noturna (p<0,005).Conclusão: Os resultados sugerem que pacientes com DGH e genótipo DD apresentam maiores benefícios coma reposição com GH em relação ao controle da PA.

Heat shock proteins in Trypanosoma cruzi: identification and localization of HSP70 and HSP60 proteins and structure of HSP60 genes (brief report)

To identify the members of the HSP70 and HSP60 families of Trypanosoma cruzi, we analysed 35S methionine epimastigote cells by two dimensional Western blot. At 29 degrees C, an HSP70 monoclonal antibody (anti-D. melanogaster) recognized eight isotypes. At least five of these were heat-induced. Polyclonal antibody against the 65 KDa antigen (anti-M. tuberculosis) recognized three isotypes with identical molecular weights, but different microliters. Only one isoform was heat induced. The cellular distribution of HSP70 and HSP60 was studied by immunoelectron microscopy. Anti-HSP70 reactive protein was localized in the cytoplasm, mitochondria and nucleus, while anti-HSP60 protein was found in the mitochondrion and in close association with the kinetoplast. To characterize the HSP60 gene and its proteins, we isolated a genomic T. cruzi clone encoding the HSP60 gene. T. cruzi HSP60 genes could be shown to be organized in 2100 nt tandem arrays. RELP in the HSP60 genes revealed that at least three different types of HSP60 genes were encoded in the T cruzi genome. The predicted open reading frame measured exhibits about 50 percent identity to other HSP60 described. Expression of these HSP60 genes could not be induced by 2 hours heat shock at 37 degrees C. Post-transcriptional mechanisms may be responsible for HSP60 induction in T. cruzi