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1.
Genes Immun ; 16(5): 311-20, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25973757

RESUMO

Systemic lupus erythematosus is a complex autoimmune disorder characterized by the production of pathogenic anti-nuclear antibodies. Previous work from our laboratory has shown that the introgression of a New Zealand Black-derived chromosome 4 interval onto a lupus-prone background suppresses the disease. Interestingly, the same genetic interval promoted the expansion of both Natural Killer T- and CD5(+) B cells in suppressed mice. In this study, we show that ablation of NKT cells with a CD1d knockout had no impact on either the suppression of lupus or the expansion of CD5(+) B cells. On the other hand, suppressed mice had an expanded population of IL-10-producing B cells that predominantly localized to the CD5(+)CD1d(low) compartment. The expansion of CD5(+) B cells negatively correlated with the frequency of pro-inflammatory IL-17 A-producing T-cells and kidney damage. Adoptive transfer with a single injection of total B cells with an enriched CD5(+) compartment reduced the frequency of memory/activated, IFNγ-producing, and IL-17 A-producing CD4 T-cells but did not significantly reduce autoantibody levels. Taken together, these data suggest that the expansion of CD5(+) IL-10-producing B cells and not NKT cells protects against lupus in these mice, by limiting the expansion of pro-inflammatory IL-17 A- and IFNγ-producing CD4 T-cells.


Assuntos
Autoimunidade , Linfócitos B/imunologia , Antígenos CD5/metabolismo , Interleucina-10/metabolismo , Lúpus Eritematoso Sistêmico/imunologia , Animais , Linfócitos T CD4-Positivos/imunologia , Antígenos CD5/genética , Memória Imunológica , Interleucina-10/genética , Camundongos , Camundongos Endogâmicos NZB
2.
Genes Immun ; 12(4): 251-62, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21307879

RESUMO

Lupus susceptibility loci on chromosome 1 have an important role in the development of autoimmunity in the New Zealand Black (NZB) mouse. We have previously shown that C57BL/6 congenic mice with an introgressed homozygous NZB chromosome 1 interval extending from ∼35 to 106 cM develop anti-nuclear antibodies and mild glomerulonephritis. In this study, we produced subcongenic mouse strains to localize the susceptibility loci in this interval and investigate how they promote autoimmunity. Our results indicate at least four susceptibility alleles and a suppressor allele. One allele is located in the 96-100 cM region and is sufficient to breach tolerance to chromatin. Addition of a second locus in the 88-96 cM interval enhances anti-dsDNA antibody production and promotes renal disease, which together with a third susceptibility allele in the 70-88 interval results in significant mortality. We further demonstrate the presence of a suppressor locus in the 35-70 or 100-102 cM interval that abrogates these phenotypes and an additional susceptibility allele in the 102-106 cM interval that restores a milder autoimmune phenotype. Several of these loci alter T-cell function. Thus, there is substantial genetic complexity in the NZB 35-106 cM interval, with disease reflecting a balance between susceptibility and suppressor loci.


Assuntos
Predisposição Genética para Doença , Lúpus Eritematoso Sistêmico/genética , Animais , Loci Gênicos , Lúpus Eritematoso Sistêmico/congênito , Lúpus Eritematoso Sistêmico/imunologia , Lúpus Eritematoso Sistêmico/patologia , Ativação Linfocitária , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos NZB , Fenótipo , Linfócitos T/imunologia , Técnicas de Cultura de Tecidos
3.
Sci Rep ; 10(1): 3812, 2020 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-32123203

RESUMO

This work presents an alternative method for fabricating Li-ion electrodes in which the use of aluminum/copper current collectors and expensive binders is avoided. Low-cost natural cellulose fibers with a 2-mm length are employed as binder and support for the electrode. The objective of this method is to eliminate the use of heavy and inactive current collector foils as substrates and to replace conventional costly binders with cellulose fibers. Moreover, no harmful solvents, such as N-methylpyrrolidone, are employed for film fabrication. Water-soluble carbons are also utilized to reduce the preparation time and to achieve a better repartition of carbon in the electrode, thus improving the electrochemical performance. Flexible and resistant LiFePO4 (LFP), Li4Ti5O12 (LTO), organic 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA), and graphite electrodes are obtained with active mass loadings similar to those obtained by the current casting method. The initial discharge capacity of approximately 130 mAh·g-1 at 2 C is obtained for an LFP/LTO paper battery with an approximately 91.6% capacity retention after 1000 cycles. An all-organic prelithiated PTCDA/graphite cell without a transition metal is prepared and electrochemically tested. It is one of the first self-standing batteries that is composed of organic redox active molecules and biodegradable components reported in literature.

4.
Sci Rep ; 10(1): 11813, 2020 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-32678243

RESUMO

We propose a innovative concept to boost the electrochemical performance of cathode composite electrodes using surface-modified carbons with hydrophilic moieties to increase their dispersion in a Lithium Nickel Manganese Cobalt Oxide (NMC) cathode and in-situ generate Li-rich carbon surfaces. Using a rapid aqueous process, the hydrophilic carbon is effectively dispersed in NMC particles followed by the conversion of its acid surface groups (e.g. -COOH), which interact with the NMC particles due to their basicity, into grafted Li salt (-COO-Li+). The solid-state batteries prepared using the cathode composites with surface-modified carbon exhibit better electrochemical performance. Such modified carbons led to a better electronic conduction path as well as facilitating Li+ ions transfer at the carbon/NMC interface due to the presence of lithiated carboxylate groups on their surface.

5.
Am J Surg Pathol ; 19(9): 1021-8, 1995 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-7661275

RESUMO

Castleman's disease (also called giant lymph node hyperplasia or angiofollicular lymph node hyperplasia) is a clinicopathological entity of unknown etiology. Two histologic patterns of lymph nodes are classically recognized: the hyaline-vascular and plasma-cell variants. Recently, multicentric Castleman's disease has emerged as a separate clinical entity manifested primarily by generalized lymphadenopathy and systemic manifestations, such as thrombocytopenia, hemolytic anemia, hepatosplenomegaly, altered liver function tests, central nervous system alterations, and autoimmune manifestations. A number of renal alterations have been described in association with the two pathological variants of Castleman's disease, but thrombotic microangiopathy has been previously reported only once in a patient with Castleman's disease. No renal biopsy was performed in that patient, although there was evidence of renal dysfunction. We report two cases of biopsy-proven renal thrombotic microangiopathy associated with multicentric Castleman's disease. In addition to having lymph node pathology characteristic of Castleman's disease, both patients presented with generalized lymphadenopathy and systemic manifestations, including acute renal failure, hypergammaglobulinemia, anemia, thrombocytopenia, and hypoalbuminemia. Autoantibodies were present in both patients, including antiphospholipid antibodies in one patient. The renal biopsies, examined by light, immunofluorescence, and electron microscopy, were diagnostic for renal thrombotic microangiopathy. The simultaneous development of two rather uncommon syndromes, multicentric Castleman's disease and renal thrombotic microangiopathy, suggests a possible link between Castleman's disease and renal thrombotic microangiopathy. Furthermore, we propose that the production of autoantibodies, in particular antiphospholipid antibodies, may lead to the development of thrombotic microangiopathy in some patients with multicentric Castleman's disease.


Assuntos
Hiperplasia do Linfonodo Gigante/complicações , Hiperplasia do Linfonodo Gigante/patologia , Rim/irrigação sanguínea , Trombose/complicações , Adulto , Idoso , Biópsia , Medula Óssea/patologia , Capilares , Imunofluorescência , Humanos , Rim/patologia , Linfonodos/patologia , Masculino , Microscopia Eletrônica
6.
Transplantation ; 67(8): 1162-7, 1999 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-10232568

RESUMO

METHOD: Despite the need to expand the donor pool, it is unclear what parameters should be used. The value of donor renal pathology and calculated creatinine clearance (CrCl) in determining recipient outcome was assessed in 57 kidney transplants from 34 donors in whom pretransplant renal biopsies were performed because of age > or =60, hypertension, and/or vascular disease. We retrospectively compared clinical outcomes in these recipients and 57 control recipients selected to have the same baseline demographics but receiving transplants from low risk donors who were significantly younger (32+/-13.9 vs. 61+/-7.3 years) and lighter weight (71+/-18.1 vs. 84+/-20.2 kg) than the high-risk donors (P<.001 for both). RESULTS: Recipients of high-risk kidneys had a higher incidence of delayed graft function, defined by a <10% fall in serum creatinine (Cr) in the first 24 hr, (56% vs. 30%, P<.01), a higher incidence of rejection (60% vs. 37%, P = .02) and a higher Cr level (197+/-64 vs. 144+/-54 micromol/L at 18 months, P<.005). Graft and patient survival were similar; 12% and 5% vs. 91% and 9% in high-risk vs. control groups, respectively (P = NS). Donor renal pathology was scored 0-3 (none to severe disease) in four areas: glomerulosclerosis, interstitial fibrosis, tubular atrophy, and vascular disease. A donor vessel score of 3/3 was associated with a 100% incidence of delayed graft function and a mean 1-year Cr level of 275+106 micromol/L (compared with 43% and 192+54 micromol/L in those with lower vessel scores, P<.05). Calculated donor CrCl <100 ml/min was associated with higher recipient Cr levels at 1 year, 240+/-95 micromol/L vs. 180+/-54 micromol/L in recipients of kidneys from donors with CrCl levels >100 ml/min (P<.05). The mean 1-year Cr level was 320+/-102 micromol/L in recipients with both a vascular score of 3/3 and a donor CrCl <100 ml/min and 184+/-63 micromol/L in those with neither factor (P = .001). CONCLUSION: Calculated donor CrCl and donor vascular pathology predict recipient graft function and may be helpful in selecting high-risk donors for single kidney transplantation.


Assuntos
Transplante de Rim , Rim/patologia , Rim/fisiopatologia , Doadores de Tecidos , Idoso , Vasos Sanguíneos/patologia , Cadáver , Creatinina/sangue , Feminino , Previsões , Humanos , Nefropatias/sangue , Nefropatias/patologia , Nefropatias/fisiopatologia , Masculino , Pessoa de Meia-Idade , Circulação Renal/fisiologia , Estudos Retrospectivos , Fatores de Risco , Fatores de Tempo , Resultado do Tratamento
7.
Am J Kidney Dis ; 38(4): 728-35, 2001 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-11576875

RESUMO

Immunoglobulin A (IgA) nephropathy is one of the most common primary types of glomerulonephritis to progress to end-stage renal disease. Its variable and often long natural history makes it difficult to predict outcome. We investigated the association of the rate of renal function decline based on the slope of creatinine clearance over time with demographic, clinical, laboratory, and histological data from 298 patients with biopsy-proven IgA nephropathy with a mean follow-up of 70 months. Using univariate analysis, urinary protein excretion at baseline and Lee pathological grading, as well as mean arterial pressure (MAP) and urinary protein excretion during follow-up, were associated with the rate of deterioration in renal function. Of these, only MAP and urinary protein excretion during follow-up were identified as independent factors by multiple linear regression analysis. The combination of best accuracy of prediction and shortest observation time using these two parameters was reached between the second and third years of follow-up. A semiquantitative method of estimating the rate of progression by using these factors was developed. These results indicate that MAP and severity of proteinuria over time are the most important prognostic indicators of IgA nephropathy. The potential relevance of the algorithm in patient management is shown.


Assuntos
Glomerulonefrite por IGA/fisiopatologia , Adolescente , Adulto , Idoso , Análise de Variância , Progressão da Doença , Feminino , Taxa de Filtração Glomerular , Glomerulonefrite por IGA/mortalidade , Glomerulonefrite por IGA/patologia , Humanos , Rim/patologia , Rim/fisiopatologia , Falência Renal Crônica/etiologia , Masculino , Pessoa de Meia-Idade , Taxa de Sobrevida
8.
Am J Clin Pathol ; 100(4): 456-62, 1993 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8213641

RESUMO

The DNA ploidy status of 53 fresh primary breast carcinomas was analyzed in a comparative study of flow cytometric (FCM) and image cytometric (ICM) analyses. Samples for FCM analysis were obtained with an in vitro fine-needle aspiration technique. Touch imprints from the same tumors were analyzed by three independent observers by ICM analysis. An ICM comparative study of "sequential" and "visually selected" nuclei also was performed. There was an overall concordance of 0.85 in the classification of diploid and nondiploid tumors by FCM and ICM analyses. In most discordant cases, a nondiploid population was identified by FCM analysis alone. This is attributed to the superior resolution of and sampling/preparatory method used for FCM analysis. There was an overall concordance of 0.91 in the classification of diploid and nondiploid tumors by ICM analysis. Selective analysis of atypical nuclei resulted in increased sensitivity in the detection of DNA aneuploid populations by ICM analysis.


Assuntos
Biópsia por Agulha , Neoplasias da Mama/genética , Carcinoma/genética , DNA de Neoplasias/análise , Citometria de Fluxo , Processamento de Imagem Assistida por Computador , Neoplasias da Mama/patologia , Carcinoma/patologia , Humanos
9.
Peptides ; 5(3): 653-4, 1984.
Artigo em Inglês | MEDLINE | ID: mdl-6473175

RESUMO

A simple and rapid method for the formylation of carboxyl-blocked peptides from their corresponding N-t-Boc precursor is described. Several examples illustrate the methodology's usefulness and compatibility with sensitive functionalities.


Assuntos
Peptídeos/síntese química , Sequência de Aminoácidos , Formiatos , Indicadores e Reagentes , Quinolinas
10.
Arch Pathol Lab Med ; 125(5): 631-6, 2001 May.
Artigo em Inglês | MEDLINE | ID: mdl-11300933

RESUMO

CONTEXT: Thin basement membrane nephropathy is recognized by a diffusely thin glomerular basement membrane (GBM) ultrastructurally. In contrast to Alport syndrome (AS), there is no GBM thickening, lamellation, or granular inclusions. Morphologically, there is overlap between thin basement membrane nephropathy and AS in female patients in whom there might be only thin GBM and no pathognomonic findings of AS. OBJECTIVE: To determine if the use of antibodies to collagen IV is helpful in making the distinction between thin basement membrane nephropathy and AS in female patients with primarily thin GBMs. DESIGN: We examined renal biopsies from 9 adult female patients with thin GBMs for the presence of alpha1, alpha3, alpha4, and alpha5 chains of type IV collagen by immunofluorescence. RESULTS: In 2 patients with segmental GBM staining, no suggestion for AS was found on physical examination or in their family history. In the remaining 7 patients with normal GBM staining, 4 had family members with end-stage renal disease of unknown etiology, raising the suspicion of X-linked or autosomal-recessive AS. Three patients were presumed to have thin basement membrane nephropathy. CONCLUSION: Segmental GBM staining for alpha3, alpha4, and alpha5 chains of type IV collagen raises the suspicion of AS in the presence of adequate controls and other supporting evidence. Normal GBM staining for alpha3, alpha4, and alpha5 chains of type IV collagen, however, does not exclude AS.


Assuntos
Anticorpos Monoclonais , Colágeno/metabolismo , Nefrite Hereditária/diagnóstico , Adulto , Membrana Basal/ultraestrutura , Colágeno/imunologia , Diagnóstico Diferencial , Feminino , Humanos , Glomérulos Renais/ultraestrutura , Microscopia Eletrônica , Microscopia de Fluorescência , Nefrite Hereditária/metabolismo , Nefrite Hereditária/patologia
11.
Int J Artif Organs ; 7(4): 209-14, 1984 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-6490193

RESUMO

Merrifield resins with various amino acid containing pendants and a water swellable polyamide resin with the peptide alanine-alanine-alanine-arginine as the pendant group have been prepared by solid phase peptide synthesis. Merrifield resins with either arginine or lysine pendants are capable of sorbing bilirubin from aqueous solution (pH = 7.8) but those with other amino acid pendants gave no indication of sorption. The polyamide-arginine resin showed, on a functional group basis, a higher capacity for bilirubin than does cholestyramine. It is proposed that the formation of salt linkages causes a strong interaction of bilirubin with arginine and lysine.


Assuntos
Bilirrubina , Nylons , Poliestirenos , Polivinil , Resinas Vegetais , Adsorção , Aminoácidos , Arginina , Nylons/síntese química , Oligopeptídeos , Poliestirenos/síntese química , Polivinil/síntese química , Resinas Vegetais/síntese química
15.
J Thromb Haemost ; 7(4): 710-9, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19192108

RESUMO

BACKGROUND AND OBJECTIVES: Anti-heat shock protein (HSP)60 autoantibodies are associated with atherosclerosis and are known to affect endothelial cells in vitro. However, their role in thrombus formation remains unclear. We hypothesized that anti-HSP60 autoantibodies could potentiate thrombosis, and evaluated the effect of anti-murine HSP60 antibodies in a ferric chloride (FeCl3)-induced murine model of carotid artery injury. METHODS: Anti-HSP60, or control, IgG was administered to BALB/c mice 48 h prior to inducing carotid artery injury, and blood flow was monitored using an ultrasound probe. RESULTS: Thrombus formation was more rapid and stable in anti-HSP60 IGG-treated mice than in controls (blood flow=1.7%+/-0.6% vs. 34%+/-12.6%, P=0.0157). Occlusion was complete in all anti-HSP60 IgG-treated mice (13/13), with no reperfusion being observed. In contrast, 64% (9/14) of control mice had complete occlusion, with reperfusion occurring in 6/9 mice. Thrombi were significantly larger in anti-HSP60 IgG-treated mice (P=0.0001), and contained four-fold more inflammatory cells (P=0.0281) than in controls. Non-injured contralateral arteries of anti-HSP60 IgG-treated mice were also affected, exhibiting abnormal endothelial cell morphology and significantly greater von Willebrand factor (VWF) and P-selectin expression than control mice (P=0.0024 and P=0.001, respectively). CONCLUSIONS: In summary, the presence of circulating anti-HSP60 autoantibodies resulted in increased P-selectin and VWF expression and altered cell morphology in endothelial cells lining uninjured carotid arteries, and promoted thrombosis and inflammatory cell recruitment in FeCl3-injured carotid arteries. These findings suggest that anti-HSP60 autoantibodies may constitute an important prothrombotic risk factor in cardiovascular disease in human vascular disease.


Assuntos
Autoanticorpos/farmacologia , Chaperonina 60/imunologia , Trombose/imunologia , Animais , Arteriopatias Oclusivas/etiologia , Arteriopatias Oclusivas/imunologia , Autoanticorpos/administração & dosagem , Doenças das Artérias Carótidas/etiologia , Doenças das Artérias Carótidas/imunologia , Cloretos , Modelos Animais de Doenças , Compostos Férricos , Camundongos , Selectina-P/análise , Fluxo Sanguíneo Regional , Reperfusão , Trombose/etiologia , Fator de von Willebrand/análise
16.
Ultrastruct Pathol ; 21(3): 235-42, 1997.
Artigo em Inglês | MEDLINE | ID: mdl-9183824

RESUMO

The role of humoral rejection in acute and chronic rejection of human renal allografts other than in hyperacute rejection has not been well established, and its importance may be underestimated. Recently, a specific histological pattern of antibody-mediated rejection of renal allografts has been recognized. The antigens targeted by this mode of rejection are not well defined but are likely located on the endothelium of small vessels (arterioles and glomerular and peritubular capillaries). In both cellular and humoral rejection, the microvasculature of transplanted organs appears to be a main target of injury. This study describes the ultrastructural changes of peritubular capillaries, over a period of up to 8 months, in 14 biopsy specimens obtained from 5 renal allograft recipients diagnosed with "pure" antibody-mediated rejection. In peritubular capillaries, there is progression of injury from necrosis of endothelial cells with lifting and denudation of basement membrane to complete disappearance of capillaries. Acutely, acute tubular necrosis is a constant finding. At 2 to 3 months post-transplantation, the remaining capillaries are dilated, misshapen, and distorted, and are surrounded by a reduplicated and thickened basement membrane. These changes are associated with increased interstitial fibrosis and tubular atrophy, comparable to a sort of renal "asphyxial" death. The author concludes that in "pure" antibody-mediated rejection, the endothelium of peritubular capillaries is a main target of injury. The potential role of antibody-mediated rejection in acute and chronic rejection of renal allografts needs to be explored further.


Assuntos
Anticorpos/imunologia , Capilares/imunologia , Capilares/patologia , Rejeição de Enxerto/imunologia , Transplante de Rim , Túbulos Renais/irrigação sanguínea , Microscopia Eletrônica , Adulto , Membrana Basal/patologia , Endotélio Vascular/patologia , Feminino , Humanos , Glomérulos Renais/irrigação sanguínea , Masculino , Pessoa de Meia-Idade , Necrose , Fatores de Tempo
17.
Rapid Commun Mass Spectrom ; 14(19): 1736-45, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-11006580

RESUMO

Electrospray ionization mass spectrometry (ESI-MS) was used to investigate metal ion interactions with salivary peptides histatin 3 (H3) and histatin 5 (H5). Conformational changes of these peptides in the presence of metal ions were studied using circular dichroism spectroscopy. H3 and H5 formed high affinity complexes with Cu(2+) and Ni(2+) and, to a lesser extent, with Zn(2+). Both peptides show the potential for multiple binding sites for Cu(2+) and Ni(2+) and only a single strong binding site for Zn(2+). The binding of a third Cu(2+) ion to H3 seems to enable the binding of a fourth ion to H3. The binding of a second and third Ni(2+) ion to H5 has a similar effect in enabling the binding of a fourth ion. None of the metal ions examined stabilized a regular secondary structure for either peptide. Subtle changes in overall conformation are seen with the addition of Cu(2+) to both H3 and H5.


Assuntos
Glicoproteínas/química , Histidina/química , Metais/química , Proteínas/química , Proteínas e Peptídeos Salivares/química , Sequência de Aminoácidos , Cátions Bivalentes/química , Dicroísmo Circular , Histatinas , Concentração de Íons de Hidrogênio , Espectrometria de Massas , Dados de Sequência Molecular , Ligação Proteica , Desnaturação Proteica
18.
Ultrastruct Pathol ; 25(1): 21-9, 2001.
Artigo em Inglês | MEDLINE | ID: mdl-11297316

RESUMO

Angiomyolipoma (AML) is a mesenchymal neoplasm of unclear histogenesis. In addition to varying amounts of smooth muscle, adipose tissue, and blood vessels, it contains a population of clear or pale eosinophilic epithelioid cells often arranged around blood vessels. Various phenotypes of AML have been described: leiomyoma-like, lipoma-like, epithelioid, and atypical. AMLs show consistent immunopositivity for HMB-45. This has been associated with the ultrastructural observation of melanosome-like structures in rare instances. In the present study, 14 AMLs from 13 patients were analyzed by electron microscopy and immunohistochemistry to determine the appearance and nature of cells composing AMLs. Overlap between cell types (spindle smooth muscle cells, epithelioid cells, and adipocytes) was found by both electron microscopy and immunohistochemistry. Melanosomes were found in 7 tumors. The cell of origin remains mysterious. Nevertheless, the study demonstrates that the AML is likely derived from a single cell that shares homology with the pericyte.


Assuntos
Angiomiolipoma/ultraestrutura , Neoplasias Renais/ultraestrutura , Neoplasias Hepáticas/ultraestrutura , Adulto , Idoso , Angiomiolipoma/química , Antígenos de Neoplasias/análise , Biomarcadores Tumorais/análise , Células Epitelioides/química , Células Epitelioides/ultraestrutura , Feminino , Seguimentos , Humanos , Imuno-Histoquímica , Neoplasias Renais/química , Neoplasias Hepáticas/química , Masculino , Antígenos Específicos de Melanoma , Melanossomas/ultraestrutura , Microscopia Eletrônica , Pessoa de Meia-Idade , Proteínas de Neoplasias/análise
19.
Appl Neuropsychol ; 3(3-4): 128-39, 1996.
Artigo em Inglês | MEDLINE | ID: mdl-16318504

RESUMO

While there have been significant theoretical advances in child neuropsychology in recent years, progress in clinical practice has been restricted owing to a lack of well standardized, developmentally appropriate assessment techniques. This paper addresses this issue, with the focus on memory and learning skills. These abilities are targeted because they are frequently impaired following brain damage in childhood, and because they are of central importance to the efficient acquisition of cognitive, educational and social skills throughout childhood. Using a normative sample of 376 children, aged 7.0 to 13.11 years, the paper describes the range of memory and learning skills in childhood, and interprets progress in these skills with reference to neurological and cognitive theory.

20.
Biochem Cell Biol ; 76(2-3): 247-56, 1998.
Artigo em Inglês | MEDLINE | ID: mdl-9923693

RESUMO

Conformational studies of the salivary peptides histatin 3 (H3) and histatin 5 (H5) were performed by NMR and circular dichroism (CD) in aqueous and nonaqueous solutions. Histatin 5 has no defined structure in H2O but adopts a more helical conformation in dimethyl sulfoxide and aqueous trifluoroethanol. This is in agreement with the CD analysis, which shows no secondary structure in H2O but increasing helical content in the presence of trifluoroethanol. CD analysis shows that H3 has less propensity to form a helical structure than H5 in similar conditions. The NMR analysis of H3 in H2O at pH 7.4 reveals that its conformational mobility is less than that of H5 as indicated by the observation of backbone cross peaks alphaN (i, i + 1) and NN (i, i + 1) and the slow exchanging amide protons in the C-terminus. However, H3 remains essentially unordered as suggested by the lack of longer range nuclear Overhauser effects (NOEs) in the NOESY spectrum. H3 becomes much more ordered in a mixture of 50:50 H2O-dimethyl sulfoxide as indicated by the numerous NOEs, including several side chain to side chain and side chain to backbone connectivities. Our data suggest that in these conditions H3 contains a turn in the region of K13 to K17 and possibly a 3(10) helix at the C-terminus. This study demonstrates that H3 and H5 are both conformationally mobile and that each adopt different types of conformations in aqueous and nonaqueous solutions.


Assuntos
Antibacterianos/química , Antifúngicos/química , Espectroscopia de Ressonância Magnética , Peptídeos , Proteínas/química , Proteínas e Peptídeos Salivares/química , Sequência de Aminoácidos , Antibacterianos/farmacologia , Antifúngicos/farmacologia , Dicroísmo Circular , Histatinas , Humanos , Dados de Sequência Molecular , Estrutura Secundária de Proteína , Proteínas/farmacologia , Proteínas e Peptídeos Salivares/farmacologia , Soluções , Solventes , Relação Estrutura-Atividade , Trifluoretanol , Água
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