RESUMO
BACKGROUND: Although mortality due to acute heart failure has decreased, its prevalence in France is still high. The aim of this study was to examine the quality of acute heart failure treatment in French emergency departments (EDs) with reference to subsequently published European Society of Cardiology (ESC) recommendations. METHODS: The medical records of patients with acute pulmonary oedema (as a marker for acute heart failure) admitted to the EDs of 11 French hospitals in 2013 were reviewed retrospectively. RESULTS: A total of 834 patients were included (median [interquartile range] age 84 [78-89] years; 48.6% male). Rates of compliance of initial management in 2013 to subsequently published 2015 recommendations were as follows: (1) thoracic ultrasound was performed in 17.3%; (2) loop diuretics were given in 75.9%; at a correct dose (among those for whom this was calculable) in 40.0% (3); intravenous nitrates were given in 21.7% of patients with systolic blood pressure>110mmHg; (4) non-invasive ventilation was initiated in 22.0% of patients with respiratory distress. Discharge summaries most often lacked a scheduled cardiologist follow-up (89.4%) and discharge patient weight (78.9%). CONCLUSIONS: The early management of patients with acute pulmonary oedema (as a marker of acute heart failure) in France in 2013 was quite different to recommendations published in 2015. A programme to implement the new recommendations is in place, and a repeat evaluation will be conducted in 2017.
Assuntos
Insuficiência Cardíaca/terapia , Qualidade da Assistência à Saúde , Doença Aguda , Idoso , Idoso de 80 Anos ou mais , Serviço Hospitalar de Emergência , Feminino , França , Fidelidade a Diretrizes/estatística & dados numéricos , Insuficiência Cardíaca/complicações , Humanos , Masculino , Guias de Prática Clínica como Assunto , Edema Pulmonar/etiologia , Edema Pulmonar/terapia , Estudos RetrospectivosRESUMO
BACKGROUND: Many patients with acute ST-segment elevation myocardial infarction (STEMI) are admitted to emergency departments (EDs) of centres without percutaneous coronary intervention (PCI) facilities. The 2012 European Society of Cardiology guidelines recommend transfer to a PCI centre with a "door in - door out" (DI-DO) time≤30min. PURPOSE: To report DI-DO times in a registry of patients with acute STEMI. METHODS: The RESeau des Urgences CORonarienne (RESUCOR) is a permanent registry of patients admitted with acute STEMI in 16 hospitals in the north French Alps since 2002. In patients admitted to a non-PCI centre, the DI-DO times were split into "diagnostic time" (from admission to transfer decision) and "logistical time" (from transfer decision to discharge). RESULTS: Of 2081 patients included in the registry from 2012 to 2014, 493 were admitted directly into an ED (254 PCI centre and 239 non-PCI centre). Of those admitted into an ED of a non-PCI centre, 228 were immediately transferred to a PCI centre (76 treated with thrombolysis and 132 with primary PCI). The proportions of patients with DI-DO≤30min and median (interquartile range [IQR]) DI-DO times are reported in the Table 1. Median (IQR) DIDO times were 90.5 (69-118) min for patients treated with thrombolysis and 88 (62-147) min for primary PCI. CONCLUSIONS: DI-DO times were longer than recommended. Efforts to decrease these delays are required. Transfer with a non-PCI centre ambulance is preferable.
Assuntos
Angioplastia Coronária com Balão/estatística & dados numéricos , Serviço Hospitalar de Emergência/estatística & dados numéricos , Admissão do Paciente/estatística & dados numéricos , Transferência de Pacientes/estatística & dados numéricos , Infarto do Miocárdio com Supradesnível do Segmento ST/diagnóstico , Infarto do Miocárdio com Supradesnível do Segmento ST/epidemiologia , França , Fidelidade a Diretrizes , Acessibilidade aos Serviços de Saúde/estatística & dados numéricos , Humanos , Sistema de Registros , Estudos de Tempo e MovimentoRESUMO
BACKGROUND: In 2015, the European Society of cardiology published guidelines on the pre-hospital and early hospital management of acute cardiac failure (ACF), which included: - use of intravenous vasodilators (nitrates) when systolic blood pressure is>110mmHg; - non-invasive ventilation if oxygen saturation is<90% and/or respiratory rate is>25/min despite nasal oxygen; - using a reduced dose of intravenous furosemide (20-40mg or equivalent of the oral morning dose if already on chronic diuretic therapy) and; - early performance of echocardiography. We sought to compare the gap between these recommendations and clinical practices in French emergency departments (EDs). METHODS: We undertook a retrospective evaluation of clinical practices in 834 consecutive patients with ACF admitted in 2013 to the EDs of 16 French hospitals. Data, including patient characteristics and practices were collected from the medical records. RESULTS: Patients' mean±standard deviation age was 82±10 years and 49% were men. Clinical practices in relation to the guideline recommendations are shown in the Table 1. CONCLUSIONS: These initial data which precede publication of the current guidelines, show that use of nitrates, non-invasive ventilation, reduced diuretic dose and early echocardiography were relatively infrequent at the first point of medical care for patients presenting with ACF. These findings indicate the need for a sizable shift in practice in order to meet the new guideline recommendations. We will conduct a repeat evaluation in 2016, after implementation of a programme aimed to improve practices at these sites.
RESUMO
In the emergency department, the management of patients with pulmonary embolism depends on the early mortality risk. Outpatient care is possible in low-risk patients. We present the existing scores and the strategy proposed by the North Alps Emergency Network, which uses the simplified PESI score (Pulmonary Embolism Severity Index) to select those low-risk patients, candidates for early discharge.
Assuntos
Serviço Hospitalar de Emergência , Ambulatório Hospitalar , Embolia Pulmonar/diagnóstico , Embolia Pulmonar/terapia , Adulto , Idoso , Idoso de 80 Anos ou mais , Algoritmos , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Admissão do Paciente , Seleção de Pacientes , Estudos Prospectivos , Embolia Pulmonar/mortalidade , Medição de Risco/estatística & dados numéricos , Análise de SobrevidaRESUMO
Upon hydration, flax seeds secrete mucilages whose content and physico-chemical properties vary according to the genotype and environment. The aim of the work was to investigate the complex genetic relationships between the vegetative period, colour, size and production of seed, the composition (polysaccharides and proteins) and physico-chemical properties of soluble mucilages collected at 28 °C from seeds of 18 lines grown in St Petersburg area. The vegetative period duration was found to impact the size and production of seeds, the yield of mucilages, including the polysaccharides, and the galactosidase enzymes, as well as their composition (mainly the rhamnogalacturonan I moieties) and some of their properties (mainly viscosity). Data allowed to significantly distinguish 6 fibre lines with mucilages enriched in rhamnogalacturonan I, 6 lines with mucilages enriched in arabinoxylan including 5 linseeds and 1 mutated fibre-line, and 5 lines with mucilages enriched in homogalacturonan-like polymer including 4 fibre lines and 1 brown linseed. Seven fibre lines had mucilages particularly rich in galactose. High to very high variability was found for 14 traits. Relatively independent characters (form/shape, protein and galactosidase) were identified and could be combined by breeding, with a focus on mucilage yield, composition and properties. Main-component analyses of line characters showed a large diversity in linseeds mainly due to their different origin but small variation in Russian fibre lines with brown seeds.
Assuntos
Linho/fisiologia , Sementes/fisiologia , Cromatografia em Gel , Análise Fatorial , Linho/metabolismo , Pectinas/metabolismo , Sementes/metabolismo , Viscosidade , Xilanos/metabolismoRESUMO
The tensile properties of flax fibres might permit them to be used in composites as reinforcement in organic resin, as long as their mechanical properties are reproducible and their water sorption are reduced. In this study, to minimise the variability of mechanical properties, several samples of flax fibres were blended as a non-woven fabric. In order to reduce the water absorption of this non-woven technical fibres, an autoclave treatment was performed which was expected to remove the pectins and then to reduce the water sorption on their negative charges. The impact of autoclave pressure (0.5, 1 and 2 bars) on water sorption was investigated by using a gravimetric static equilibrium method. The Park model based on the three sorption modes: Langmuir, Henry's law and clustering, was successfully used to simulate the experimental sorption data. The lowest pressure treatments impacted only the Langmuir contribution while the 2 bar autoclave-treatment positively impacted the water resistance in the core of fibres by reducing Henry's absorption rate. This was shown to be related to the chemical modifications at the surface and in the core of fibres. A schematic model is presented relating the water sorption and the pectic composition of the fabric.
RESUMO
This study is focused on enzymatically upgrading the functional properties of flax fibres. Green flax fibres were treated with a polygalacturonase and a pectate lyase (PaL) and their properties were compared with dew-retted fibres. Morphological observations, vapour-sorption analyses and mechanical measurements showed that PaL-treatment was able not only to mime retting in terms of bundle division, but also to improve the mechanical properties of technical fibres. Conversely, these properties were shifted down after the polygalacturonase treatment, mainly due to the presence of contaminating glycanases. At the level of the elementary fibres, nanoindentation data indicated the highest stiffness of the secondary wall for PaL-treated fibres. The tensile properties exhibited equal, but moderate values of the Young's modulus (â¼37±14GPa) and breaking strength (â¼650±300MPa) for retted and PaL-treated fibres; we hypothesize an impact of the growth conditions on the fibre chemical structure with an excess of matrix pectins compared to the amount of glucomannan coating the cellulose microfibrils.
RESUMO
Selective serotonin reuptake inhibitors (SSRIs) are a widely prescribed group of antidepressants. We report three cases of photosensitivity induced by fluvoxamine and paroxetine. These photoallergic reactions suggest cross-reactivity between different molecules. Methylation metabolism could explain common photosensitization. Although these drugs are widely prescribed, such photosensitization is rare. Nevertheless, we consider that clinicians and patients should be aware of the risk of photosensitization and these drugs should be stopped before phototherapy or prolonged sun exposure.
Assuntos
Antidepressivos/efeitos adversos , Fluvoxamina/efeitos adversos , Transtornos de Fotossensibilidade/induzido quimicamente , Inibidores Seletivos de Recaptação de Serotonina/efeitos adversos , Antagonistas do Receptor 5-HT2 de Serotonina , Idoso , Toxidermias/etiologia , Feminino , Humanos , Masculino , Pessoa de Meia-IdadeRESUMO
In this work, in order to improve the adhesion between a polyester matrix (unsaturated polyester resin) and flax fibres (Linum usitatissimum L.) and to increase their moisture resistance, chemical surface treatments have been used. These different treatments were performed with maleic anhydride (MA), acetic anhydride (Ac), silane (Si) and styrene (S). The modified flax fibres were characterized by means of infrared spectroscopy and surface energy analysis. The effect of these treatments on water sorption was investigated by using a gravimetric static equilibrium method. Water sorption isotherms were derived from kinetic data. The Park model based on the three sorption modes: Langmuir, Henry's law and clustering, was successfully used to simulate the experimental sorption data. It was found that the (Ac) and particularly (S) treatments reduced overall water uptake of flax fibres. We show that tensile modulus, breaking strength and breaking strain depend on the chemical treatment used.
Assuntos
Linho/química , Fenômenos Mecânicos , Água/química , Adsorção , Difusão , Cinética , Modelos Químicos , Espectrofotometria Infravermelho , Vapor , Propriedades de Superfície , Temperatura , Resistência à TraçãoRESUMO
In the course of our studies on the putative role of pectins in the control of cell growth, we have investigated the effect of cadmium on their composition, remodelling and distribution within the epidermis and fibre tissues of flax hypocotyl (Linum usitatissimum L.). Cadmium-stressed seedlings showed a significant inhibition of growth whereas the hypocotyl volume did not significantly change, due to the swelling of most tissues. The structural alterations consisted of significant increase of the thickness of all cell walls and the marked collapse of the sub-epidermal layer. The pectic epitopes recognized by the anti-PGA/RGI and JIM5 antibodies increased in the outer parts of the epidermis (external tangential wall and junctions) and fibres (primary wall and junctions). Concomitantly, there was a remarkable decrease of JIM7 antibody labelling and consequently an increase of the ratio JIM5/JIM7. Conversely, the ratio JIM7/JIM5 increased in the wall domains closest to the plasmalemma, which would expel the cadmium ions from the cytoplasm. The hydrolysis of cell walls revealed a cadmium-induced increase of uronic acid in the pectic matrix. Sequential extractions showed a remodelling of both homogalacturonan and rhamnogalacturonan I. In fractions enriched in primary walls, the main part of the pectins became cross-linked and could be extracted only with alkali. In fractions enriched in secondary walls, the homogalacturonan moieties were found more abundantly in the calcium-chelator extract while the rhamnogacturonan level increased in the boiling water extract.
Assuntos
Cádmio/farmacologia , Linho/crescimento & desenvolvimento , Hipocótilo/metabolismo , Pectinas/metabolismo , Parede Celular/fisiologia , Parede Celular/ultraestrutura , Linho/efeitos dos fármacos , Linho/ultraestrutura , Hipocótilo/efeitos dos fármacos , Hipocótilo/ultraestrutura , Microscopia Eletrônica , Plântula/efeitos dos fármacos , Plântula/fisiologia , Plântula/ultraestrutura , Sementes/efeitos dos fármacos , Sementes/fisiologiaRESUMO
BACKGROUND: Efficacy and safety of an alpha-tocopherol-enriched emulsion incorporating soybean, coconut, olive, and fish oils (SMOF) are compared in terms of biologic parameters to those of soybean oil-based emulsion (LIPOVEN). METHODS: Twenty stressed patients were randomly assigned in a double-blind study to receive at least a 5-day course of total parenteral nutrition. Plasma activities of liver enzymes, C-reactive protein, antioxidant capacity, alpha-tocopherol, retinol, and low density lipoprotein (LDL)-alpha-tocopherol levels were determined. LDL-lipid oxidation is measured after incubation of the LDL in the presence of a prooxidant. RESULTS: The plasma activities of liver enzymes and the phospholipids/apo A1 ratio were increased in both groups. However, in the SMOF group the increases were lower than in the LIPOVEN group and non-significant for the CRP plasma level and the alanineamino-transferase activity. Before parenteral nutrition, the plasma antioxidant status was markedly reduced in both groups. After parenteral nutrition discontinuation, the antioxidant capacity and the amount of LDL-derived oxidation by-products formed were comparable in both groups. There was a significant improvement in plasma lipophilic antioxidant vitamins and LDL-alpha-tocopherol levels only in the SMOF group. CONCLUSIONS: The lower increase of plasma liver enzymes and phospholipids/apo A1 ratio in the SMOF group suggest a better liver function than in the LIPOVEN group. This beneficial effect results in a higher liver mobilization and plasma levels of lipophilic antioxidants. They could, together with higher delivery of omega-3 fatty acids to peripheral tissues, contribute positively to survival rate of stressed patients.
Assuntos
Antioxidantes/metabolismo , Emulsões Gordurosas Intravenosas/química , Fígado/efeitos dos fármacos , Fígado/fisiologia , Nutrição Parenteral Total/métodos , Idoso , Alanina Transaminase/metabolismo , Apolipoproteína A-I/metabolismo , Proteína C-Reativa/análise , Cuidados Críticos/métodos , Método Duplo-Cego , Emulsões Gordurosas Intravenosas/administração & dosagem , Feminino , Óleos de Peixe , Humanos , Fígado/enzimologia , Masculino , Pessoa de Meia-Idade , Azeite de Oliva , Fosfolipídeos/metabolismo , Óleos de Plantas , Cuidados Pós-Operatórios , Estudos Prospectivos , Segurança , Óleo de Soja , Substâncias Reativas com Ácido Tiobarbitúrico/análise , Resultado do Tratamento , alfa-Tocoferol/administração & dosagem , alfa-Tocoferol/sangueRESUMO
Flax fibers have been the subject of many biochemical studies, which revealed that cellulose and pectins are the major constituents of their walls. In contrast, little is known about the location of these polymers within the walls of mature fibers by microscopic methods. This has been technically hampered by the very thick secondary wall of fibers, resulting in inadequate tissue preservation unsuitable for immunogold microscopy. In this study, we adapted the basic chemical fixation, dehydration and infiltration methods to achieve a good preservation of the cell structures of mature fibers and reduced damage to antigens. We were able to apply postembedding immunocytochemical techniques to map the location of various pectic epitopes within the walls of mature fibers. Our immunolabeling data show that homogalacturonans were exclusively found in the middle lamellae and the cell junctions but were not detectable in the secondary wall. In contrast, rhamnogalacturonan I (RG I)-associated epitopes, as well as galactan and arabinan epitopes, were abundantly distributed over the secondary wall of mature fibers.
Assuntos
Linho/ultraestrutura , Polissacarídeos/metabolismo , Resinas Acrílicas , Parede Celular/metabolismo , Parede Celular/ultraestrutura , Epitopos , Linho/metabolismo , Imuno-Histoquímica , Microscopia Eletrônica , Pectinas/metabolismo , Caules de Planta/metabolismo , Caules de Planta/ultraestrutura , Inclusão do TecidoRESUMO
Immunosenescence involves modifications of humoral and cellular immunity. In a previous study, we have shown a locus-dependent reduction of HLA class-I cell surface expression on peripheral lymphocytes and monocytes with advancing age. Here we report the quantitative analysis of HLA-A and -B transcripts from PBL of 54 healthy subjects aged 21-90 years. Using a competitive RT-PCR method, we observed a significant decrease of HLA-A (P < 0.0001) and -B (P = 0.0025) mRNA contents with increasing age. Secondly, to investigate this locus-dependent alteration of HLA class-I transcription, we performed EMSA using nuclear extracts from PBL of five young (24-31-year-old) and 5 elderly (58-69 years old) donors with locus A and B sequences of the Enh-A as probes. No qualitative variation of EMSA profiles appeared between the two groups of donors with 6 and 4 bandshift for the locus A and B, respectively. Quantitatively, we observed a significant increase of B4 intensity in the elderly group compared to the young group (P < 0.05). These results suggest that the variation of DNA binding protein could contribute to the lower transcription of HLA-A and -B with ageing. These alterations of HLA class-I expression at the transcriptional level could lead to the unresponsiveness of CD8 T cells due to default of antigen presentation with ageing.
Assuntos
Envelhecimento/imunologia , Antígenos HLA-A/biossíntese , Antígenos HLA-B/biossíntese , Leucócitos/imunologia , Adulto , Idoso , Extratos Celulares/química , Núcleo Celular/metabolismo , Proteínas de Ligação a DNA/análise , Feminino , Antígenos HLA-A/genética , Antígenos HLA-B/genética , Humanos , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase , RNA Mensageiro/biossíntese , Sensibilidade e Especificidade , Transcrição GênicaRESUMO
Four transcriptional enhancers lie downstream of the immunoglobulin heavy chain locus: Calpha3'/hs3a, hs1,2, hs3b, and hs4. Although individually weak, these elements have strong transcriptional synergies when combined and they altogether behave as a locus control region. Previous knockout experiments in the 3' region have shown that both hs3a and hs1,2 are dispensable for normal expression and rearrangement of the IgH locus but that their replacement with a transcribed neo gene severely affects class switch recombination. Here we show that even in the absence of a neo gene, joint deletion of the last two 3' enhancers, hs3b and hs4, severely impairs germline transcription and class switching to most isotypes and may in addition affect mu gene expression in resting B cells.
Assuntos
Switching de Imunoglobulina/genética , Cadeias Pesadas de Imunoglobulinas/genética , Região de Controle de Locus Gênico/genética , Recombinação Genética , Animais , Linfócitos B , Elementos Facilitadores Genéticos , Heterozigoto , Homozigoto , Isotipos de Imunoglobulinas/biossíntese , Imunoglobulina M/biossíntese , Cadeias mu de Imunoglobulina/genética , Tecido Linfoide , Camundongos , Camundongos Transgênicos , RNA Mensageiro/biossíntese , Deleção de Sequência , Baço/imunologiaRESUMO
Galactosyltransferases (GalTs), capable of transferring a galactosyl residue from UDP-galactose (UDP-Gal) to polysaccharide acceptor, were solubilized from flax (Linum usitatissimum L.) membranes using 0.5% CHAPS. The observed requirement for a rhamnogalacturonan I (RG-I) exogenous substrate to stimulate the solubilized GalT activity provided the first evidence for the presence of RG-I GalT activities in flax cells. An assay to measure specifically the products of this RG-I GalT activity was designed, based on size-exclusion chromatography. Labelled products were characterized as an RG-I polymer by using purified RG-I hydrolase or lyase. At pH 8 and in the presence of 5 mM CaCl2, beta-D-galactosyl residues were specifically transferred onto RG-I branches of short beta-(1 --> 4)-D-galactan side chains. These side chains were liable to hydrolysis by beta-galactosidase and endo-beta-(1 --> 4)-D-galactanase. The RG-I GalT had a temperature optimum of 30 degrees C. an apparent Km for UDP-Gal and exogenous RG-I substrate of 460 +/- 40 microM and 1.1 +/- 0.1 mg ml(-1) respectively, and a Vmax of 3.0 +/- 0.5 pkat mg(-1) protein.
Assuntos
Linho/enzimologia , Galactosiltransferases/metabolismo , Pectinas/biossíntese , Pectinas/metabolismo , Membrana Celular , Parede Celular/química , Células Cultivadas , Detergentes/farmacologia , Glicosídeo Hidrolases/metabolismo , Concentração de Íons de Hidrogênio , Microssomos/enzimologia , Pectinas/química , Pectinas/isolamento & purificação , Pectinas/farmacocinética , Uridina Difosfato Galactose/química , Uridina Difosfato Galactose/metabolismo , Uridina Difosfato Galactose/farmacocinéticaRESUMO
Three pectin methyltransferases (PMT5, PMT7, PMT18; EC 2.1.1.6.x) were solubilized from the endo-membrane complex of flax cells, with 0.05% Triton X-100. After a 3 step-chromatography procedure, PMT7 and PMT5 were purified to apparent homogeneity. PMT5 and PMT7 differed regarding their optimum pH (5 or 7), the methyl acceptor (low or highly methylesterified pectin), their focusing pH range (6-7 or 8-9) and relative molecular mass (40 +/- 5 or 110 +/- 10 kDa). SDS-PAGE of PMT5 and PMT7 did not reveal bands at 40 or 110 kDa but only a silver stained band of about 18 kDa. Two independent methods (photo labelling and enzymatic activity) showed that this silverstained band corresponded to a methyltransferase with affinity for pectins. This polypeptide was of the same size as the enzyme designed PMT18 (18 +/- 3 kDa; pl 4-4.5) recovered during size exclusion chromatography of either PMT7 or PMT5, suggesting that PMT18 bears the catalytic site of PMT5 and PMT7.
Assuntos
Linho/enzimologia , Proteínas Virais/isolamento & purificação , Eletroforese em Gel de Poliacrilamida , Focalização Isoelétrica , Microssomos/enzimologia , Peso Molecular , Marcadores de Fotoafinidade , Proteínas do Movimento Viral em Plantas , Solubilidade , Especificidade por Substrato , Proteínas Virais/química , Proteínas Virais/metabolismoRESUMO
We studied the hs1,2 transcriptional enhancer identified downstream of the human alpha1 gene of the immunoglobulin H (IgH) locus, for which two different allelic configurations (a and b) were previously reported by Southern blotting. By using a polymerase chain reaction (PCR) method we amplified minisatellites within the hs1,2 core enhancer, with variable numbers of tandem repeats (VNTR) defining three 'PCR alleles' alpha1A, alpha1B and alpha1C (including one, two and three repeats, respectively). Five different alpha1 h1,2 genotypes were encountered in a population of 513 donors, representing 13.8, 34.5, 49.7, 1.3 and 0.6% for the AA, BB, AB, AC and BC genotypes, respectively. Luciferase assays showed that increasing the number of minisatellites increased the transcriptional strength of the alpha1 hs1,2 enhancer. Simultaneous determination of Southern blot alleles and VNTR alleles only showed a partial linkage between both types of polymorphism, altogether defining at least six different allelic forms of the 3'alpha1 region. In conclusion, the present study further demonstrates the genetic instability of the 3'alpha region, for which multiple alleles have been generated through inversions and internal deletions and/or duplications. This study also strengthens the hypothesis that the polymorphism at the IgH 3' regulatory region of the alpha1 gene could play a role in the outcome of diseases involving immunoglobulin secretion.
Assuntos
Elementos Facilitadores Genéticos/imunologia , Cadeias Pesadas de Imunoglobulinas/genética , Polimorfismo Genético , Regiões 3' não Traduzidas/imunologia , Alelos , Sequência de Bases , Southern Blotting , Expressão Gênica , Humanos , Imunoglobulina A/sangue , Repetições Minissatélites/imunologia , Dados de Sequência Molecular , Reação em Cadeia da Polimerase , Transcrição GênicaRESUMO
The quantification of plasmatic HLA class-I molecules (sHLA-I) was realized by a sandwich ELISA using a monomorphic mAb (W6/32). sHLA-I concentration is significantly increased in the elderly group (>50 years, 0.429+/-0.301 microg ml(-1)) as compared to the young group (<50 years, 0.126+/-0.085 microg ml(-1)). The variation of sHLA-I content could contribute to the unresponsiveness of ageing immune system.
Assuntos
Envelhecimento/imunologia , Antígenos HLA/sangue , Antígenos de Histocompatibilidade Classe I/sangue , Envelhecimento/sangue , HumanosRESUMO
Well-characterized pectin samples with a wide range of degrees of esterification (39-74%) were incubated with the solubilized pure alpha and gamma isoforms of pectinmethylesterase, from mung bean hypocotyl (Vigna radiata). Enzyme activity was determined at regular intervals along the deesterification pathway at pH 5.6 and pH 7.6. It has been demonstrated that the distribution of the carboxyl units along the pectin backbone controls the activity of the cell wall pectinmethylesterases to a much greater extent than the methylation degree, with a random distribution leading to the strongest activity. Polygalacturonic acid was shown to be a competitive inhibitor of the alpha isoform activity at pH 5.6 and to inhibit the gamma isoform activity at both pH 5.6 and pH 7.6. Under these conditions, the drop in enzyme activity was shown to be correlated to the formation of deesterified blocks of 19 +/- 1 galacturonic acid residues through simulations of the enzymatic digestion according to the mechanisms established previously (Catoire, L., Pierron, M., Morvan, C., Herve du Penhoat, C., and Goldberg, R. (1998) J. Biol. Chem. 273, 33150-33156). However, even in the absence of inhibition by the reaction product, activity dropped to negligible levels long before the substrate had been totally deesterified. Comparison of alpha and gamma isoform cDNAs suggests that the N-terminal region of catalytic domains might explain their subtle differences in activity revealed in this study. The role of pectinmethylesterase in the cell wall stiffening process along the growth gradient is discussed.