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1.
Reumatismo ; 75(4)2023 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-38115772

RESUMO

OBJECTIVE: To compare etanercept and adalimumab biosimilars (SB4 and ABP501) and respective bioriginators in terms of safety and efficacy in a real-life contest. METHODS: We consequently enrolled patients affected by rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis, treated with SB4, and ABP501, or with corresponding originators, belonging to the main biological prescribing centers in the Lazio region (Italy), from 2017 to 2020. Data were collected at recruitment and after 4, 8, 12, and 24 months of therapy. RESULTS: The multicenter cohort was composed by 455 patients treated with biosimilars [SB4/ABP501 276/179; female/male 307/146; biologic disease-modifying anti-rheumatic drug (b-DMARD) naïve 56%, median age/ interquartile range 55/46-65 years] and 436 treated with originators (etanercept/adalimumab 186/259, female/ male 279/157, b-DMARD naïve 67,2%, median age/interquartile range 53/43-62 years). No differences were found about safety, but the biosimilar group presented more discontinuations due to inefficacy (p<0.001). Female gender, being a smoker, and being b-DMARD naïve were predictive factors of reduced drug survival (p=0.05, p=0.046, p=0.001 respectively). The retention rate at 24 months was 81.1% for bioriginators and 76.5% for biosimilars (median retention time of 20.7 and 18.9 months, respectively) (p=0.002). Patients with remission/low disease activity achievement at 4 months showed a cumulative survival of 90% to biosimilar therapy until 24 months (p=0.001); early adverse reactions instead represented a cause of subsequent drug discontinuation (p=0.001). CONCLUSIONS: Real-life data demonstrated a similar safety profile between biosimilars and originators, but a reduced biosimilar retention rate at 24 months. Biosimilars could be considered a valid, safe, and less expensive alternative to originators, allowing access to treatments for a wider patient population.


Assuntos
Antirreumáticos , Artrite Reumatoide , Medicamentos Biossimilares , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adalimumab/uso terapêutico , Artrite Reumatoide/tratamento farmacológico , Medicamentos Biossimilares/uso terapêutico , Medicamentos Biossimilares/efeitos adversos , Etanercepte/uso terapêutico , Etanercepte/efeitos adversos , Necrose/induzido quimicamente , Necrose/tratamento farmacológico , Resultado do Tratamento , Adulto
2.
Clin Exp Immunol ; 205(1): 12-27, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-33772754

RESUMO

Systemic sclerosis (SSc) is an autoimmune disease characterized by significant vascular alterations and multi-organ fibrosis. Microvascular alterations are the first event of SSc and injured endothelial cells (ECs) may transdifferentiate towards myofibroblasts, the cells responsible for fibrosis and collagen deposition. This process is identified as endothelial-to-mesenchymal transition (EndMT), and understanding of its development is pivotal to identify early pathogenetic events and new therapeutic targets for SSc. In this review, we have highlighted the molecular mechanisms of EndMT and summarize the evidence of the role played by EndMT during the development of progressive fibrosis in SSc, also exploring the possible therapeutic role of its inhibition.


Assuntos
Células Endoteliais/patologia , Endotélio/patologia , Transição Epitelial-Mesenquimal/fisiologia , Escleroderma Sistêmico/patologia , Animais , Fibrose/patologia , Humanos , Miofibroblastos/patologia
3.
Lupus ; 28(14): 1705-1711, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31707917

RESUMO

OBJECTIVE: To evaluate the impact of duration of remission on the health-related quality of life (HRQoL) of patients with systemic lupus erythematosus (SLE). METHODS: We conducted a 5-year retrospective study on two Italian cohorts. Remission was defined as a continuative period of no clinical disease activity, according to the Systemic Lupus Erythematosus Disease Activity Index 2 K, and a permitted maximum prednisone dose of 5 mg/day. HRQoL was measured using the 36-Item Short-Form Health Survey (SF36) during the last visit. RESULTS: We enrolled 136 female SLE patients. During observation, 15 (11%) patients had been in remission for ≥1 and <2 years, 15 (11%) for ≥2 and <3 years, 19 (14%) for ≥3 and <4 years, 9 (7%) for ≥4 and <5 years, and 53 (39%) had been in prolonged remission for ≥5 years. In the multivariate model, considering depression and fatigue as covariates, patients in prolonged remission showed significantly better scores in the physical functioning (p = 0.039), role physical (p = 0.029), bodily pain (p = 0.0057), general health (p = 0.0033) and social functioning (p = 0.0085) components of the SF36, compared with those in remission <5 years or unremitted. Subsequent mediation analyses found that these effects were partly influenced by depression. CONCLUSION: Lupus remission could improve the HRQoL of SLE patients, particularly when associated with appropriate management of depression and fatigue.


Assuntos
Depressão/epidemiologia , Fadiga/epidemiologia , Lúpus Eritematoso Sistêmico/complicações , Qualidade de Vida , Adulto , Feminino , Humanos , Itália/epidemiologia , Modelos Lineares , Lúpus Eritematoso Sistêmico/tratamento farmacológico , Masculino , Pessoa de Meia-Idade , Prednisona/administração & dosagem , Indução de Remissão , Estudos Retrospectivos , Índice de Gravidade de Doença , Inquéritos e Questionários
4.
Lupus ; 26(14): 1463-1472, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28786768

RESUMO

Background Systemic lupus erythematosus is associated with an increased risk of cardiovascular disease. Low-dose aspirin, hydroxychloroquine and statins have been suggested to play a prophylactic role of cardiovascular events. This study is devoted to reviewing the literature on the topic and assessing the effects of these drugs in preventing a first cardiovascular event in a two-centre Italian series. Methods A PubMed search on cardiovascular prevention in systemic lupus erythematosus was performed. Moreover, systemic lupus erythematosus patients admitted to two centres from 2000-2015, who at admission had not experienced any cardiovascular event, were investigated. Aspirin, hydroxychloroquine and statin use, and the occurrence of any cardiovascular event, were recorded at each visit. Kaplan-Meier and Cox regression analyses were performed to evaluate the role of traditional, disease-related cardiovascular risk factors and of each of the three drugs in the occurrence of new cardiovascular events. Results The literature search produced conflicting results. Two hundred and ninety-one systemic lupus erythematosus patients were included in the study and followed for a median of eight years. During follow-up, 16 cardiovascular events occurred. At multivariate analysis, taking aspirin (hazard ratio: 0.24) and hydroxychloroquine for more than five years (hazard ratio: 0.27) reduced, while antiphospholipid antibody positivity (hazard ratio: 4.32) increased, the risk of a first cardiovascular event. No effect of statins emerged. Conclusion Our study confirms an additive role of aspirin and hydroxychloroquine in the primary prophylaxis of cardiovascular events in Italian patients with systemic lupus erythematosus. The lack of any detected effect in previous reports may depend on the design of studies and their short follow-up period.


Assuntos
Doenças Cardiovasculares/prevenção & controle , Lúpus Eritematoso Sistêmico/complicações , Prevenção Primária/métodos , Adulto , Anticorpos Antifosfolipídeos/imunologia , Aspirina/administração & dosagem , Doenças Cardiovasculares/etiologia , Feminino , Humanos , Hidroxicloroquina/administração & dosagem , Inibidores de Hidroximetilglutaril-CoA Redutases/administração & dosagem , Masculino , Fatores de Risco
6.
Int J Immunopathol Pharmacol ; 25(4): 1157-65, 2012.
Artigo em Inglês | MEDLINE | ID: mdl-23298507

RESUMO

Neuropsychiatric manifestations are not rarely associated with systemic lupus erythematosus (SLE). Magnetic resonance angiography and positron emission tomography can provide excellent images of cerebral perfusion and metabolism whereas information is still lacking on a possible diagnostic role of ultrasound. In this study we aim to assess whether duplex sonography of neck and intracranial vessels may be useful in distinguishing patients with and without neuropsychiatric SLE (NPSLE). Neck and transcranial duplex sonography was performed by a single operator on 33 women affected by SLE (mean age +/- SD: 47.69+/-8.17 years) and on 15 healthy control subjects. Nineteen patients presented NPSLE. Pulsatility and resistivity indices (PI and RI) were automatically calculated by the ultrasound instrument in internal carotid (ICA) and middle cerebral artery (MCA), on both sides, according to standard methods. No significant haemodynamic differences were found in mean and median PI and RI values of ICA and MCA comparing SLE with NPSLE patients and with healthy control subjects. No correlation was found between MCA and ICA parameters in the same group of patients. Duplex sonography of cerebral vessels is unable to distinguish SLE and NPSLE patients. Heterogeneity of causes in the pathogenesis of NPSLE and the different vascular adaptation of cerebral macrocirculation as opposed to cerebral microcirculation may represent possible reasons that explain the inability of ultrasound to differentiate SLE patients from NPSLE patients.


Assuntos
Ecoencefalografia , Lúpus Eritematoso Sistêmico/diagnóstico por imagem , Vasculite Associada ao Lúpus do Sistema Nervoso Central/diagnóstico por imagem , Adulto , Idoso , Artéria Carótida Interna/fisiopatologia , Artérias Cerebrais/fisiopatologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
7.
Eur Rev Med Pharmacol Sci ; 25(14): 4810-4817, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34337730

RESUMO

OBJECTIVE: Patients with Parkinson's disease (PD) are at a higher risk of hospitalization and recurrent hospitalizations, with consequent complications. Polypharmacy is associated with several adverse outcomes, including hospitalization, increased length of hospital stay, and mortality. The aim of this study was to evaluate among patients with PD the association between the number of medications and incident hospitalizations. PATIENTS AND METHODS: We analysed the data of 165 patients with Parkinson's disease attending a geriatric Day Hospital who were enrolled in a cohort study and followed for a median of two years. RESULTS: Over the follow-up, 46 participants (46%) were hospitalized at least one time; multiple admissions were observed in 12 subjects (7%). The median number of agents was 5 (4-7). In Cox regression, the number of drugs was associated with increased hospitalization rates (HR=1.23; 95% CI=1.06-1.43), also after excluding non-neurological medications (HR=1.18; 95% CI=1.01-1.38). Using Poisson regression, polypharmacy (i.e., use of >5 drugs) predicted the number of repeated hospitalizations (IRR=2.62; 95% CI=1.28-5.36; p=.008). CONCLUSIONS: Among patients with PD, the number of daily medications is associated with increased risk of hospitalization; an increasing number of drugs is associated with increasing number of hospitalizations.


Assuntos
Hospitalização , Fármacos Neuroprotetores/efeitos adversos , Doença de Parkinson/tratamento farmacológico , Idoso , Estudos de Coortes , Feminino , Humanos , Tempo de Internação , Modelos Logísticos , Masculino , Polimedicação , Estudos Retrospectivos , Fatores de Risco
8.
Clin Exp Med ; 20(1): 31-37, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31679095

RESUMO

Raynaud's phenomenon (RP) is a clinical disorder characterized by recurrent, reversible episodes of digital vasospasm. RP can be classified as primary (pRP) or secondary, depending on whether it occurs as a benign condition (not disease-associated) or is associated with other diseases, mainly of the connective tissues. In both cases, it can be triggered by environmental factors, as indicated by the increased incidence of pRP episodes following exposure to cold, vibration injury or chemicals. The purpose of this prospective case-control study was to assess, in an Italian cohort of 132 pRP patients, the association of the phenomenon with demographic, lifestyle habits, environmental and work-related factors. Compared to healthy controls, pRP was found to be inversely associated with the use of contact lenses (OR = 0.4; p = 0.004) and of chlorous-based disinfectants (OR = 0.3; p < 0.001) and directly associated with the presence of prosthesis implants (OR = 5.3; p = 0.001) and the use of hydrogen peroxide-based compounds (OR = 2.6; p = 0.002), suggesting that the latter should be avoided in RP affected patients. Multivariate and multivariable analysis confirmed the associations. Further investigations are needed to understand the mechanism(s) underlying these findings.


Assuntos
Lentes de Contato/estatística & dados numéricos , Peróxido de Hidrogênio/efeitos adversos , Próteses e Implantes/efeitos adversos , Doença de Raynaud/epidemiologia , Adulto , Estudos de Casos e Controles , Desinfetantes/química , Feminino , Humanos , Incidência , Itália/epidemiologia , Estilo de Vida , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Estudos Prospectivos , Próteses e Implantes/estatística & dados numéricos , Doença de Raynaud/etiologia
9.
Eur Rev Med Pharmacol Sci ; 22(5): 1451-1456, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29565506

RESUMO

OBJECTIVE: Due to the aging of populations, the prevalence of hearing loss and osteoporosis is increasing. Previous studies have found an association between these conditions. Nevertheless, the pathophysiologic pathway of such an association has not yet been established. The present study aimed at evaluating the association, if any, of hearing loss with osteoporosis in an older unselected population, and whether this association varied according to inflammatory status. PATIENTS AND METHODS: We assessed the association of osteoporosis with a self-reported hearing loss in all 310 subjects aged 75+ living in Tuscania (Italy), without exclusion criteria. Bone density was assessed by calcaneal quantitative ultrasound; osteoporosis was defined as a T-score ≤ -2.5 Standard Deviation. RESULTS: Hearing loss was associated with osteoporosis (OR = 1.84, 95% CI = 1.03-3.28; p = 0.40) in multivariable logistic regression analysis, after adjusting for potential confounders. Analysis of the interaction term indicated that this association varied according to the erythrocyte sedimentation rate, ERS (p = 0.030), and high-sensitivity C reactive protein, hs-CRP (p = 0.017) but not sex (p = 0.832). Of notice, this association was significant only for higher levels of inflammatory parameters (OR = 2.82; 95% CI = 1.15-6.90; p = 0.023 for the higher ERS tertile; and OR = 3.81; 95% CI = 1.36-10.63; p = 0.011 for the higher hs-CRP tertile vs. lower tertiles). CONCLUSIONS: Hearing loss is associated with osteoporosis in community dwelling elderly. Such an association seems to depend upon higher inflammation levels.


Assuntos
Perda Auditiva/etiologia , Inflamação/complicações , Osteoporose/complicações , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Modelos Logísticos , Masculino
10.
Eur Rev Med Pharmacol Sci ; 20(7): 1295-9, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27097949

RESUMO

OBJECTIVE: Primary Sjogren's Syndrome (pSS) is a systemic autoimmune disorder characterized by infiltration of the exocrine glands leading to secretory insufficiency. Despite the progress made in understanding the pathogenesis of the SS, many aspects remain to be clarified. Interleukin-33 (IL33) is a recently discovered cytokine, belonging to IL-1 superfamily. IL33 and its soluble receptor ST2 were implied in a number of immune and in autoimmune diseases pathogenesis. In this work ,we analyzed expression of IL33 and ST2 in Sjogren's syndrome. PATIENTS AND METHODS: Serum IL-33 and soluble ST2 were analyzed using commercial ELISA kit in 15 pSS, 9 patients with Systemic Lupus Erythematosus and 9 controls. RESULTS: We found significant hyperexpression of sST2 in sera of SS patients and SLE patients compared to healthy subjects (p = 0.04 and p = 0.07, respectively). In pSS, sST2 levels in pSS positively correlated with activity index SSDAI (r = 0.662, p = 0.007). In SLE, we found positive correlation between ST2 and SLEDAI 2K (r = 0.685, p = 0.04). Circulating levels of IL-33 were detectable in 2 of 15 SS patients, in 2 SLE patients and in 1 of control subjects. CONCLUSIONS: We found an hyperexpression of sST2 in pSS and SLE patients with a possible immune modulatory role, because of a substantial suppression of circulating IL33. In our pSS and SLE cohort, sST2 levels were in correlation with disease activity indices.


Assuntos
Progressão da Doença , Proteína 1 Semelhante a Receptor de Interleucina-1/sangue , Interleucina-33/sangue , Síndrome de Sjogren/sangue , Adulto , Idoso , Biomarcadores/sangue , Estudos de Coortes , Citocinas/sangue , Citocinas/imunologia , Ensaio de Imunoadsorção Enzimática , Feminino , Humanos , Proteína 1 Semelhante a Receptor de Interleucina-1/imunologia , Interleucina-33/imunologia , Masculino , Pessoa de Meia-Idade , Síndrome de Sjogren/imunologia
12.
Eur Rev Med Pharmacol Sci ; 20(4): 636-41, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26957264

RESUMO

OBJECTIVE: Crescent literature data demonstrated a role of adipokines in immune responses, particularly leptin is involved in wide spectrum of pro-inflammatory functions. Several evidences suggested that leptin is able to inhibit T regulatory cells proliferation and function in vitro models. In the present study, we investigate the relationship between leptin and circulating T regulatory cells (Tregs) in patients affected by systemic lupus erythematosus (SLE). PATIENTS AND METHODS: 13 SLE patients and 11 healthy controls were enrolled. Metabolic syndrome and cardiovascular parameters were evaluated. Serum leptin levels were detected by commercial ELISA kit and circulating regulatory T cells were determined by FACS analysis as CD4+CD25highFOP3+ lymphocytes. RESULTS: Metabolic syndrome, defined by ATPIII criteria, was more prevalent in SLE compared to controls (38.4% vs. 0%, p = 0.04), as well as arterial hypertension (38.4% vs. 0%, p = 0.04). We did not find significant differences in mean leptin levels among SLE and controls (13.13 ± 1.51 ng/ml vs. 9.48 ± 8.67 ng/ml, p = 0.6). Mean Tregs percentage of total CD4 were 1.27 ± 0.9 in SLE vs. 2.8 ± 1.2 in healthy controls (p = 0.001). We found a negative correlation between leptin levels and Tregs percentage of total CD4 in SLE patients (r = 0.4, p = 0.01). CONCLUSIONS: Our results suggest a role of leptin in the regulation of circulating T regulatory cells amount in human SLE.


Assuntos
Leptina/sangue , Lúpus Eritematoso Sistêmico/sangue , Lúpus Eritematoso Sistêmico/diagnóstico , Linfócitos T Reguladores/metabolismo , Adipocinas/sangue , Adulto , Biomarcadores/sangue , Linfócitos T CD4-Positivos/metabolismo , Proliferação de Células/fisiologia , Estudos de Coortes , Feminino , Humanos , Ativação Linfocitária/fisiologia , Masculino , Síndrome Metabólica/sangue , Síndrome Metabólica/diagnóstico , Pessoa de Meia-Idade
13.
Int J Food Microbiol ; 51(2-3): 105-11, 1999 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-10574086

RESUMO

Lactic Acid Bacteria (LAB) isolated from various traditional Thai fermented foods were screened for exopolysaccharides (EPS) production. From 104 isolates, two rod-shaped and five coccal-shaped LAB were able to produce EPS from sucrose on solid media. However, only the cocci were capable of producing EPS in liquid media and these were identified as Pediococcus pentosaceus. Pediococcus pentosaceus strains AP-1 and AP-3 produced EPS in high yield. In liquid media containing sucrose as carbon source, the amount of EPS produced by AP-1 and AP-3 strains was 6.0 and 2.5 g/L, respectively. The isolated and purified EPSs were chemically characterized. On the basis of sugar composition, methylation analysis and nuclear magnetic resonance spectroscopy, both the EPSs were shown to belong to the same dextran class. In particular, both EPSs differed from linear dextran by branching through 3,6-di-Osubstituted alpha-D-glucopyranosyl residues. The EPS from P. pentosaceus AP-3 was characterized by a relatively higher degree of branching and by a higher molecular weight than that from P. pentosaceus AP-1.


Assuntos
Microbiologia de Alimentos , Cocos Gram-Positivos/isolamento & purificação , Ácido Láctico , Polissacarídeos Bacterianos/isolamento & purificação , Animais , Técnicas Bacteriológicas , Decápodes/microbiologia , Fermentação , Produtos Pesqueiros/microbiologia , Espectroscopia de Ressonância Magnética , Produtos da Carne/microbiologia , Oryza/microbiologia , Pediococcus/isolamento & purificação , Suínos , Chá/microbiologia , Tailândia
14.
Carbohydr Res ; 257(2): 227-38, 1994 May 05.
Artigo em Inglês | MEDLINE | ID: mdl-8013006

RESUMO

Pyruvate groups occur naturally in many microbial polysaccharides as nonsaccharidic components and significantly affect their physicochemical and biological properties. The configuration of the acetal carbon of pyruvate groups is mainly influenced by the favoured equatorial orientation of the methyl group. Evaluation of conformational energies has been carried out to assess the relative stabilities of the R and S isomers as a function of configuration and torsional angles for several residue models, including methyl 4,6-O-(1-carboxyethylidene)-alpha-D-galactopyranoside (1). Different levels of theoretical approach are used ranging from ab initio, semiempirical (AM1), and molecular mechanics (MM) methods up to molecular dynamics (MD). The higher stability of the isomer R of 1 was demonstrated by all of the methods used, thus giving full agreement with the NMR data on the natural compounds.


Assuntos
Polissacarídeos/química , Piruvatos/química , Acetais , Configuração de Carboidratos , Galactosídeos/química , Modelos Moleculares , Conformação Molecular , Piruvatos/análise
15.
Carbohydr Res ; 223: 227-34, 1992 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-1596921

RESUMO

The exopolysaccharides fro Rhizobium meliloti YE-2 extracted 10 days after the inoculum from culture broths and having different osmolarity values (0, 0.2, 0.4, and 0.6 M) have been investigated by means of oscillatory and steady-shear measurements on 1% solutions in 0.1M NaCl. The micro-organism produces a mixture of a galactoglucan and a succinoglycan. At low osmolarity (0 and 0.2M), the main fraction consists of galactoglucan and the viscoelastic properties of the mixture are typical of an entanglement system. At 0.4 and 0.6M, the proportion of the succinoglycan increases and the viscoelastic properties change abruptly to those typical of a "weak gel" system. Different conformations are adopted by the two exopolysaccharides in solution.


Assuntos
Polissacarídeos Bacterianos/química , Sinorhizobium meliloti/crescimento & desenvolvimento , Configuração de Carboidratos , Sequência de Carboidratos , Elasticidade , Dados de Sequência Molecular , Concentração Osmolar , Polissacarídeos Bacterianos/isolamento & purificação , Viscosidade
16.
Carbohydr Res ; 231: 117-35, 1992 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-1394308

RESUMO

The physicochemical solution properties of the galactoglucan excreted by Rhizobium meliloti strain YE-2(S1) have been investigated by capillary viscometry, potentiometric titration, isothermal mixing microcalorimetry, and circular dichroism. Potentiometric and chiro-optical data, as a function of the degree of ionisation, indicate the absence of a co-operative conformational transition. Solution properties, as a function of ionic strength and temperature, suggest that the galactoglucan adopts a disordered conformation characterised by moderate flexibility. Polyelectrolyte theory is used to fit the enthalpy of dilution data with a suitable linear charge-density parameter. Conformational calculations and chain modelling, using molecular mechanics, give an unperturbed characteristic ratio, (C infinity) of 20, which was smaller than that estimated from intrinsic-viscosity and molecular-weight data for an expanded-coil chain model.


Assuntos
Polissacarídeos Bacterianos/química , Sinorhizobium meliloti/química , Calorimetria , Configuração de Carboidratos , Sequência de Carboidratos , Dicroísmo Circular , Indicadores e Reagentes , Cinética , Modelos Moleculares , Dados de Sequência Molecular , Rotação Ocular , Polissacarídeos Bacterianos/isolamento & purificação , Potenciometria , Soluções
17.
Carbohydr Res ; 265(2): 167-79, 1994 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-7842440

RESUMO

In order to obtain information on the location of succinate and acetate groups, comparative NMR analyses were carried out on succinoglycans from different microbial sources by using conventional and advanced NMR techniques. In particular, one-dimensional, 1H and 13C NMR spectra were recorded for qualitative and quantitative analysis on native high-molecular-weight succinoglycans (both in the Na+ salt and free-acid forms) from Pseudomonas sp. NCIB 11592, Agrobacterium radiobacter A201-25, Rhizobium meliloti YE-2, and Rhizobium sp. isolated from Vicia faba and compared with those of the deacylated and deacylated-depyruvated, partially depolymerised exopolysaccharides from Rhizobium meliloti YE-2. Moreover, a series of two-dimensional experiments was performed on all the exopolysaccharides aiming at the partial assignment of the NMR spectra. The NMR data showed that succinate is located on O-6 of either one or both of the two side chain 3-linked beta-D-Glc residues, whereas the acetate (when it is present) is located on one of the O-6 of backbone 4-linked beta-D-Glc units, but the specific site could not be determined. In addition, the spectral features of the succinate substituent were found to be sensitive to pH changes.


Assuntos
Bactérias/química , Polissacarídeos Bacterianos/química , Acetatos/análise , Configuração de Carboidratos , Sequência de Carboidratos , Isótopos de Carbono , Hidrogênio , Espectroscopia de Ressonância Magnética/métodos , Dados de Sequência Molecular , Polissacarídeos Bacterianos/isolamento & purificação , Pseudomonas/química , Rhizobium/química , Sinorhizobium meliloti/química , Succinatos/análise
18.
Int J Biol Macromol ; 15(4): 201-7, 1993 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-8373738

RESUMO

The solution properties of the capsular polysaccharide produced by Klebsiella pneumoniae SK1, SK1-CPS, were investigated by various methods. The SK1-CPS repeating unit is a branched pentasaccharide containing one glucuronic acid as single unit side chain; acetyl groups are present as non-carbohydrate substituents on the uronic acid residue in non-stoichiometric amounts. Chiro-optical, potentiometric, viscometric and rheological measurements have been performed in order to characterize the conformational behaviour of the polymer in water and in aqueous salt solutions. Under the investigated experimental conditions, changes of temperature, ionic strength and pH were shown not to induce any cooperative conformational transition. All the results obtained suggest that the solution conformation of SK1-CPS is a random coil with a certain degree of chain flexibility. The removal of the acetyl substituents apparently does not modify the overall conclusions drawn for the native polymer, except for an incipient tendency to aggregation revealed for high salt conditions.


Assuntos
Klebsiella pneumoniae/química , Polissacarídeos Bacterianos/química , Configuração de Carboidratos , Sequência de Carboidratos , Concentração de Íons de Hidrogênio , Dados de Sequência Molecular , Polissacarídeos Bacterianos/isolamento & purificação , Potenciometria , Reologia , Soluções , Temperatura , Viscosidade
19.
Int J Biol Macromol ; 16(2): 65-70, 1994 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-8011589

RESUMO

This paper reports some physicochemical properties of the capsular polysaccharide produced by Klebsiella pneumoniae serotype K40 (K40-CPS) in aqueous solution. The polymer has a linear hexasaccharide repeating unit containing one glucuronic acid residue as the only ionizable group. Potentiometric, viscometric, chiro-optical and rheological measurements have been carried out over a range of ionic strength, pH and temperature, with the aim of characterizing the conformational state of the polysaccharide in aqueous solution. All the data reported indicate that the K40-CPS does not undergo a cooperative conformational transition under the investigated experimental conditions. Furthermore, the viscosity data and the viscoelastic spectra suggest that the K40-CPS is rather flexible and adopts a random coil conformation in solution.


Assuntos
Klebsiella pneumoniae/química , Polissacarídeos Bacterianos/química , Sequência de Carboidratos , Dicroísmo Circular , Concentração de Íons de Hidrogênio , Conformação Molecular , Dados de Sequência Molecular , Concentração Osmolar , Reologia , Soluções , Temperatura , Viscosidade
20.
Int J Biol Macromol ; 19(3): 157-63, 1996 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-8910055

RESUMO

An acidic exopolysaccharide was isolated from a selected strain of Aureobasidium pullulans. On the basis of spectroscopic and chromatographic techniques, the polymer was identified as a beta-D-glucan containing a main chain of (1-->3)-linked beta-D-glucopy-ranosyl units substituted at the O-6 position by single beta-D-glucopyranosyl side chains. The ratio of units in the main chain to units in the side chain was found to be 1.4:1. The ionic character of this exopolysaccharide is due to the presence of malate residues which are linked to the polymer through ester bonds. The degree of substitution was estimated to be very low (0.05). In aqueous solution no signals are present in the NMR spectra strongly suggesting that the polymer adopts a rigid ordered conformation as further confirmed by rheological data. A solvent-induced conformational transition was observed in DMSO in which NMR spectra with good signal-to-noise ratio were obtained. The solution behaviour of the polymer is similar to that of other branched (1-->3)-beta-D-glucans in spite of both the degree of branching and the substitution with malate groups.


Assuntos
Glucanos/química , Fungos Mitospóricos/química , beta-Glucanas , Configuração de Carboidratos , Sequência de Carboidratos , Concentração de Íons de Hidrogênio , Espectroscopia de Ressonância Magnética/métodos , Malatos/análise , Malatos/química , Dados de Sequência Molecular , Reologia/métodos , Soluções , Espectroscopia de Infravermelho com Transformada de Fourier , Viscosidade
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