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1.
J Appl Microbiol ; 130(3): 948-959, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32866324

RESUMO

AIMS: To identify the bacteria nodulating Sulla spinosissima growing profusely in a lead and zinc mine tailings in Eastern Morocco. METHODS AND RESULTS: In all, 32 rhizobial cultures, isolated from root nodules of S. spinosissima growing in soils of the mining site, were tolerant to different heavy metals. The ERIC-polymerase chain reaction (PCR) fingerprinting analysis clustered the isolates into seven different groups, and the analysis of the 16S rRNA sequences of four selected representative strains, showed they were related to different species of the genus Mesorhizobium. The atpD, glnII and recA housekeeping genes analysis confirmed the affiliation of the four representative strains to Mesorhizobium camelthorni CCNWXJ40-4T , with similarity percentages varying from 96·30 to 98·30%. The sequences of the nifH gene had 97·33-97·78% similarities with that of M. camelthorni CCNWXJ40-4T ; however, the nodC phylogeny of the four strains diverged from the type and other reference strains of M. camelthorni and formed a separated cluster. The four strains nodulate also Astragalus gombiformis and A. armatus but did not nodulate A. boeticus, Vachellia gummifera, Prosopis chilensis, Cicer arietinum, Lens culinaris, Medicago truncatula, Lupinus luteus or Phaseolus vulgaris. CONCLUSIONS: Based on similarities of the nodC symbiotic gene and differences in the host range, the strains isolated from S. spinosissima growing in soils of the Sidi Boubker mining site may form a different symbiovar within Mesorhizobium for which the name aridi is proposed. SIGNIFICANCE AND IMPACT OF THE STUDY: In this work, we show that strains of M. camelthorni species nodulating S. spinosissima in the arid area of Eastern Morocco constitute a distinct phylogenetic clade of nodulation genes; we named symbiovar aridi, which encompasses also mesorhizobia from other Mediterranean desert legumes.


Assuntos
Fabaceae/microbiologia , Chumbo/metabolismo , Mesorhizobium/fisiologia , Mineração , Simbiose , Proteínas de Bactérias/genética , Genes Essenciais/genética , Especificidade de Hospedeiro , Mesorhizobium/classificação , Marrocos , Filogenia , Nodulação/genética , RNA Ribossômico 16S/genética , Nódulos Radiculares de Plantas/microbiologia , Microbiologia do Solo , Simbiose/genética
2.
Br J Dermatol ; 183(4): 710-718, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32017013

RESUMO

BACKGROUND: Patient-reported outcome measures (PROMs) aimed at assessing people with systemic sclerosis (SSc) have rarely involved the target population in the item- and domain-generation stage of the instrument construction. OBJECTIVES: To develop a new PROM assessing activities and participation in people with SSc. METHODS: A provisional International Classification of Functioning, Disability and Health (ICF)-based 65-item questionnaire previously developed from interviews of people with SSc was sent by email to all patients followed in the internal medicine department of Cochin hospital (n = 184) and enrolled in the Scleroderma Patient-centered Intervention Network Cohort. Items were reduced according to their metric properties. Dimensional structure of the questionnaire was assessed by principal component analysis, convergent and divergent validities by Spearman's rank correlation coefficient, internal consistency by Cronbach's α, and reliability by a test-retest method using the intraclass correlation coefficient (ICC) and Bland-Altman analysis. RESULTS: Overall, 113 of 184 patients (61·4%) completed the provisional questionnaire. The item-reduction process resulted in a 17-item questionnaire, the Cochin 17-item Scleroderma Functional scale (CSF-17). Principal component analysis extracted two dimensions: 10 items related to mobility (CSF-17 section A) and seven items related to general tasks (CSF-17 section B). We observed convergent validity of the CSF-17 total score with global activity limitation, pain, depression and aesthetic burden, and divergent validity with anxiety. Cronbach's α was 0·94 for section A and 0·95 for section B. ICC (n = 25 patients) was 0·92 for the CSF-17 total score. Bland-Altman analysis did not reveal a systematic trend for the test-retest. CONCLUSIONS: The CSF-17 is a new PROM assessing activities and participation specifically in people with SSc. Its content and construct validities are very high. What is already known about this topic? In the earliest stages of construction patient-reported outcomes (PROMs) for people with systemic sclerosis (SSc) rarely involve the target population. Instruments able to capture the specific needs of people with SSc in terms of activities and participation are lacking. What does this study add? The Cochin 17-item Scleroderma Functional Scale (CSF-17) is a new PROM assessing global activities and participation specifically in people with SSc. Patients' perspectives were prioritized at all stages of construction. What are the clinical implications of this work? The CSF-17 could be used in clinical practice and research to assess the efficacy of complex multidisciplinary interventions targeting activity limitations and participation restriction in people with SSc. Linked Comment: Clark and Denton. Br J Dermatol 2020; 183:610.


Assuntos
Pessoas com Deficiência , Escleroderma Sistêmico , Humanos , Medidas de Resultados Relatados pelo Paciente , Reprodutibilidade dos Testes , Inquéritos e Questionários
3.
Int J Pharm ; 574: 118882, 2020 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-31786355

RESUMO

The aim of the current study was to characterize the robustness of an integrated continuous direct compression (CDC) line against disturbances from feeding, i.e. impulses of API and short step disturbances. These disturbances mimicked typical variations that can be encountered during long-term manufacture. The study included a primary formulation, with API of standard particle size, which was manufactured at 5 and 10 kg/h production rates, and a modified formulation, with API of large particle size, which was manufactured at 5 kg/h production rate. Overall, the CDC line smoothened all the disturbances, fulfilling the USP uniformity of dosage units (UDU) limit for single tablets. However, runs with the modified formulation failed the pharmacopoeia UDU requirements for the entire run due to high variation between tablets. The primary formulation passed the requirements in all cases. The residence time distribution (RTD) results indicated that the primary formulation allowed better smoothening ability, and an increase in production rate led to poorer smoothening due to shorter RTD. The RTDs revealed that a substantial part of back-mixing took place after the blender. Thus, the tablet press has an important role in smoothening disturbances longer than the mean residence time of the blender, which was very short.


Assuntos
Comprimidos/química , Química Farmacêutica/métodos , Tamanho da Partícula , Pressão , Tecnologia Farmacêutica/métodos
4.
Acta Biomater ; 49: 575-589, 2017 02.
Artigo em Inglês | MEDLINE | ID: mdl-27888100

RESUMO

An important aim of bone regenerative medicine is to design biomaterials with controlled chemical and topographical features to guide stem cell fate towards osteoblasts without addition of specific osteogenic factors. Herein, we find that sprayed bioactive and biocompatible calcium phosphate substrates (CaP) with controlled topography induce, in a well-orchestrated manner, Wharton's jelly stem cells (WJ-SCs) differentiation into osteoblastic lineage without any osteogenic supplements. The resulting WJ-SCs commitment exhibits features of native bone, through the formation of three-dimensional bone-like nodule with osteocyte-like cells embedded into a mineralized type I collagen. To our knowledge, these results present the first observation of a whole differentiation process from stem cell to osteocytes-like on a synthetic material. This suggests a great potential of sprayed CaP and WJ-SCs in bone tissue engineering. These unique features may facilitate the transition from bench to bedside and the development of successful engineered bone. STATEMENT OF SIGNIFICANCE: Designing materials to direct stem cell fate has a relevant impact on stem cell biology and provides insights facilitating their clinical application in regenerative medicine. Inspired by natural bone compositions, a friendly automated spray-assisted system was used to build calcium phosphate substrate (CaP). Sprayed biomimetic solutions using mild conditions led to the formation of CaP with controlled physical properties, good bioactivity and biocompatibility. Herein, we show that via optimization of physical properties, CaP substrate induce osteogenic differentiation of Wharton's jelly stem cells (WJ-SCs) without adding osteogenic supplement factors. These results suggest a great potential of sprayed CaP and WJ-SCs in bone tissue engineering and may facilitate the transition from bench to beside and the development of clinically successful engineered bone.


Assuntos
Osso e Ossos/citologia , Fosfatos de Cálcio/farmacologia , Diferenciação Celular , Osseointegração/efeitos dos fármacos , Células-Tronco/citologia , Geleia de Wharton/citologia , Materiais Biocompatíveis/farmacologia , Diferenciação Celular/efeitos dos fármacos , Células Cultivadas , Humanos , Microscopia de Força Atômica , Osteoblastos/citologia , Osteoblastos/efeitos dos fármacos , Osteogênese/efeitos dos fármacos , Células-Tronco/ultraestrutura , Propriedades de Superfície
5.
Transplant Proc ; 48(9): 3064-3066, 2016 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27932147

RESUMO

The growing disparity between organ supply and demand has become the greatest hurdle facing transplant professionals and life-saving transplants. Because the organ shortage has become the rate-limiting step to effective transplants, it is critical for the transplant community to identify viable mechanisms to expand the donor pool and use every available allograft. Although using kidneys from deceased donors whose demise was secondary to ethylene glycol (EG) toxicity requires great deliberation and precise timing as described by Barbas et al [5], using hepatic allografts in this setting involves far less risk. The following is a discussion of a 61-year-old male who was diagnosed with end-stage liver disease secondary to non-alcoholic steatohepatitis and ultimately underwent a life-saving transplant with a liver recovered from a donor with EG-induced brain death and allocated nationally due to trepidation by local and regional centers to use the liver from a donor after EG toxicity.


Assuntos
Morte Encefálica , Doença Hepática Terminal/cirurgia , Transplante de Fígado/métodos , Doadores de Tecidos/provisão & distribuição , Obtenção de Tecidos e Órgãos/métodos , Adulto , Etilenoglicol/intoxicação , Humanos , Masculino , Pessoa de Meia-Idade , Suicídio , Transplante Homólogo/métodos , Transplantes/fisiologia
6.
Med Sante Trop ; 25(1): 97-101, 2015.
Artigo em Francês | MEDLINE | ID: mdl-25847883

RESUMO

Leishmaniasis in its cutaneous form is a public health problem in Morocco. The objectives of this study were to assess the development of its epidemiological profile, identify the relevant species, and determine the location of the identified cases and their distribution by year, by sex, and by age. This retrospective epidemiological study covers a period of 88 years and concerns all reported cases of cutaneous leishmaniasis (CL) in Morocco from the first description in 1922 until 2010. During this period, 56,194 cases have been reported; they account for 95.7% of all cases of leishmaniasis (n = 58,710). The endemicity of CL has changed over time. The increase in its incidence is likely to be explained both by improved reporting and by a real increase in the number of cases.


Assuntos
Leishmaniose Cutânea/epidemiologia , Adolescente , Adulto , Distribuição por Idade , Criança , Pré-Escolar , Feminino , Humanos , Incidência , Lactente , Masculino , Pessoa de Meia-Idade , Marrocos/epidemiologia , Estudos Retrospectivos , Distribuição por Sexo , Adulto Jovem
7.
Ann Phys Rehabil Med ; 58(2): 66-73, 2015 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25770007

RESUMO

OBJECTIVES: Identify key informational and educational items ("messages") to provide to physicians (general practitioners and specialists) and physiotherapists for the management of pain induced by exercise and mobilization (PIEM). Develop checklists to improve this management in daily practice. MATERIAL AND METHODS: The Delphi method for consensus-building was used to identify informational and educational messages for health professionals who deal with PIEM. Informed by the results of an extensive qualitative study, a panel of experts from 5 medical and paramedical disciplines concerned with PIEM and a representative of a patients' association were interviewed individually and iteratively in order to obtain a single, convergent opinion. RESULTS: Delphi consultation helped to determine 9 areas corresponding to 54 key messages of information and education for doctors and physiotherapists who deal with PIEM. These messages relate to: defining, characterizing, identifying, and evaluating PIEM; identifying factors that may cause or increase this pain; informing the patient in order to avoid misinterpretation of PIEM; preventing and treating PIEM; and dealing with it during physical therapy sessions. The method also enabled us to develop 2 synthetic instruments (checklists) - 1 for physicians and 1 for physiotherapists - to help with the management of this pain. CONCLUSION: Consulting a panel of experts comprising different categories of actors dealing with PIEM on the basis of a thorough qualitative diagnosis in order to identify messages for a training program makes it possible to harmonize programs with the expectations of patients and the problems encountered by professionals. The formulation of this program and the institutionalization of two checklists should enable health professionals to identify, qualify, and deal more effectively with PIEM.


Assuntos
Lista de Checagem , Manejo da Dor/métodos , Medição da Dor/métodos , Dor/diagnóstico , Fisioterapeutas , Adulto , Técnica Delphi , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Dor/etiologia , Modalidades de Fisioterapia/efeitos adversos , Pesquisa Qualitativa
11.
Biomed Mater Eng ; 24(1 Suppl): 53-61, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24928918

RESUMO

Stem cells are the most powerful candidate for the treatment of various diseases. Suitable stem cell source should be harvested with minimal invasive procedure, found in great quantity, and transplanted with no risk of immune response and tumor formation. Fetal derived stem cells have been introduced as an excellent alternative to adult and embryonic stem cells use, but unfortunately, their degree of "stemness" and molecular characterization is still unclear. Several studies have been performed deciphering whether fetal stem cells meet the needs of regenerative medicine. We believe that a transcriptomic screening of Wharton's jelly stem cells will bring insights on cell population features.


Assuntos
Testes Genéticos/métodos , Células-Tronco Mesenquimais , Geleia de Wharton/citologia , Adesão Celular/efeitos dos fármacos , Diferenciação Celular , Células Cultivadas , Células-Tronco Embrionárias , Matriz Extracelular/química , Humanos , Medicina Regenerativa , Transcriptoma , Cordão Umbilical/citologia , Cordão Umbilical/metabolismo , Geleia de Wharton/metabolismo
12.
Biomed Mater Eng ; 24(1 Suppl): 63-73, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24928919

RESUMO

BACKGROUND: To favor regeneration following critical bone defect, a combination of autologous bone graft and biomaterials is currently used. Major drawbacks of such techniques remain the availability of the autologous material and the second surgical site, inducing pain and morbidity. OBJECTIVE: Our aim was to investigate the biocompatibility in vitro of three dimensions hybrid biodegradable scaffolds combining osteoconductive properties of hydroxyapatite and anti-inflammatory properties of chitosan. METHODS: Hybrid scaffolds were characterized by microscopic observations, equilibrium swelling ratio and overtime weight loss measurements. In vitro studies were performed using primary human bone cells cultured for 7, 14 and 21 days. Cell viability, proliferation, morphology and differentiation through alkaline phosphatase (ALP) activity measurement were assessed. RESULTS: Characterization of our scaffolds demonstrated porous, hydrophilic and biodegradable characteristics. In vitro studies showed that these scaffolds have induced slight decrease in cell death and proliferation comparing to the culture plastic substrate control condition, as well as increased short term osteoinductive properties. CONCLUSIONS: In this study, we have provided evidence that our hybrid hydroxyapatite/chitosan scaffolds could be suitable for bone filling.


Assuntos
Osso e Ossos/química , Quitosana/química , Durapatita/química , Engenharia Tecidual/métodos , Alicerces Teciduais/química , Fosfatase Alcalina/metabolismo , Materiais Biocompatíveis/química , Biodegradação Ambiental , Diferenciação Celular , Proliferação de Células , Sobrevivência Celular , Células Cultivadas , Humanos , L-Lactato Desidrogenase/metabolismo , Microscopia Eletrônica de Varredura
13.
J Mycol Med ; 23(3): 185-8, 2013 Sep.
Artigo em Francês | MEDLINE | ID: mdl-23896621

RESUMO

Infective endocarditis is rare in children, it is rarer after a surgical treatment of atrioventricular canal, and it is exceptional that Candida albicans is the etiologic agent. This is a serious infection found in congenital heart disease with or without surgery. It is potentially lethal, despite diagnostic and therapeutic advances. We report a case of infective endocarditis due to C. albicans after the treatment of a congenital systemic atrioventricular canal in a child with trisomy 21. The diagnosis was suspected on clinical manifestations and cardiac auscultation. Confirmation was provided by positive blood cultures and echocardiography. The large size of the vegetation in the patient was in favor of a fungal etiology, blood cultures allowed to identify the fungus. This observation illustrates a poorly understood disease, with very poor prognosis and which is a potential complication of heart surgery. The improved prognosis should be achieved by shortening the time to diagnosis and optimizing the therapeutic support.


Assuntos
Candida albicans , Candidíase/complicações , Endocardite/microbiologia , Insuficiência da Valva Mitral/cirurgia , Candida albicans/isolamento & purificação , Candidíase/microbiologia , Pré-Escolar , Síndrome de Down/complicações , Síndrome de Down/cirurgia , Endocardite/complicações , Evolução Fatal , Defeitos dos Septos Cardíacos , Humanos , Masculino , Insuficiência da Valva Mitral/complicações , Complicações Pós-Operatórias/microbiologia
14.
J Fr Ophtalmol ; 36(7): 600-3, 2013 Sep.
Artigo em Francês | MEDLINE | ID: mdl-23790444

RESUMO

We report the case of a 21-year-old male patient admitted emergently with progressive bilateral severe visual loss for 1 month. Posterior segment examination revealed bilateral stellate neuroretinitis. Infectious serologies were negative, and brain CT was normal. Physical examination was remarkable for malignant hypertension of 220/150 mmHg. Diagnostic work-up revealed a pheochromocytoma documented by histopathological exam upon adrenalectomy. The disc edema and macular exudates resolved once the hypertension was controlled.


Assuntos
Neoplasias das Glândulas Suprarrenais/diagnóstico , Feocromocitoma/diagnóstico , Retinite/diagnóstico , Neoplasias das Glândulas Suprarrenais/complicações , Diagnóstico Diferencial , Humanos , Hipertensão/complicações , Hipertensão/diagnóstico , Masculino , Feocromocitoma/complicações , Retinite/etiologia , Adulto Jovem
15.
J Fr Ophtalmol ; 36(6): 537-42, 2013 Jun.
Artigo em Francês | MEDLINE | ID: mdl-23618733

RESUMO

PURPOSE: To evaluate risk factors for failure of scleral buckling in rhegmatogenous retinal detachment (RRD) in an adult Moroccan population. METHODS: A retrospective study of 432 eyes of 422 patients undergoing scleral buckling (SB) for primary RRD between 2001 and 2009 was carried out. Statistical analysis of risk factors for failure was performed using binary logistic regression. RESULTS: Mean patient age was 43 ± 15 years, and 45.4% were myopic. The median recurrence was at 10 months. The final failure rate was 22.5%. Univariate analysis shows that significant risk factors for failure were extent of RRD ≥ 3 quadrants (P<0.001), advanced PVR (P<0.001) and worsening PVR postoperatively (P<0.001). In the multivariate model, the only significant risk factor for failure was the worsening postoperative PVR (P<0.001). CONCLUSIONS: Our findings suggest that worsening of PVR after surgery is the major risk factor for failure of SB in RRD. Thus, it is necessary to recognize the risk factors contributing to PVR and to plan the most appropriate, earliest and least traumatic surgical treatment of RRD.


Assuntos
Complicações Pós-Operatórias/etiologia , Descolamento Retiniano/cirurgia , Recurvamento da Esclera , Adulto , Estudos de Coortes , Diagnóstico Tardio/estatística & dados numéricos , Oftalmopatias Hereditárias/diagnóstico , Oftalmopatias Hereditárias/epidemiologia , Oftalmopatias Hereditárias/cirurgia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Marrocos/epidemiologia , Complicações Pós-Operatórias/epidemiologia , Descolamento Retiniano/diagnóstico , Descolamento Retiniano/epidemiologia , Estudos Retrospectivos , Fatores de Risco , Recurvamento da Esclera/métodos , Recurvamento da Esclera/reabilitação , Recurvamento da Esclera/estatística & dados numéricos , Falha de Tratamento
16.
Int J Pharm ; 437(1-2): 250-2, 2012 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-22939963

RESUMO

It is now a clearly established fact that ultraviolet radiation is involved in the induction of skin cancer such as carcinoma and melanoma. The most efficient means of protection is by using clothes. For uncovered areas, it is essential to apply a sun product. For some time, various authors have been wondering about the inefficiency or indeed the dangerousness of sun products. Cases of sunburn are still just as frequent in children. We have chosen to study the influence of the quantity of sun product applied on the skin on the level of efficiency obtained. Twenty commercially-available products with SPFs varying between 10 and 50+ and belonging to all levels of protection, that is to say "low", "medium" and "high", were tested in vitro at 5 different doses (5.0, 7.5, 10.0, 12.5 and 15.0 mg for a surface area of 25 cm(2)). We were able to demonstrate that there was a polynomial relationship between the SPF and the quantity of product on the skin's surface. It can be seen that when the dose is halved, the SPF is divided by a variable factor according to the product, from 1.5 to 3.8.


Assuntos
Fator de Proteção Solar , Protetores Solares/administração & dosagem , Relação Dose-Resposta a Droga , Neoplasias Cutâneas/prevenção & controle
17.
Pharmazie ; 63(1): 58-60, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-18271305

RESUMO

European legislation currently authorizes 26 sun filters among which, there is only one mineral filter: titanium dioxide. In the United States, two mineral filters are authorized: titanium dioxide in a maximum dose of 25% and zinc oxide. Zinc oxide is authorized in Europe, but its concentration level is not limited. A large number of commercial products are containing one of these mineral filters. The difference between these products lies in the percentage of the active substance, the way they are incorporated into the final product and the size of the primary particles. Depending on the ingredient used, there is a large variation in efficacy. The efficacy of the products tested was determined by an in vitro method using a spectrophotometer equipped with an integration sphere. Titanium dioxide was thus seen to be much more effective than zinc oxide; indeed no commercial form of zinc oxide tested can give a sun protection factor (SPF) higher than 10 at its maximum dose of use, unlike titanium dioxide which in its coated form (coated with alumina and with stearic acid, amongst others) gives a SPF of 38. This study has also allowed us to dispel the theory that talc--a raw material which has been used empirically for years in foundation in the belief that it has photoprotective effects--has an effect against sun rays. Talc proved to be particularly ineffective, as when it is used at a level of 25%, it only gives a totally negligible SPF of one unit.


Assuntos
Minerais/farmacologia , Protetores Solares/farmacologia , Titânio/farmacologia , Óxido de Zinco/farmacologia , Algoritmos , Química Farmacêutica , Minerais/química , Espectrofotometria Ultravioleta , Protetores Solares/química , Talco , Titânio/química , Raios Ultravioleta , Óxido de Zinco/química
18.
J Colloid Interface Sci ; 255(2): 403-9, 2002 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-12505089

RESUMO

The microstructure of complexes between hydroxypropyl-cyclodextrins (HPCDs) (alpha, beta, and gamma) and a novel gemini surfactant has been investigated by small-angle neutron scattering (SANS). This nonionic hetero-gemini surfactant (denoted NIHG750) contains two hydrophobic groups and two hydrophilic groups. One is a methyl-capped polyoxyethylene chain with 16 oxyethylene units and the other is a secondary hydroxyl group. Various form factor models have been considered for fitting the SANS data. Spherical aggregates (25 to 40 A) with a size slightly larger than that of NIHG750 micelles (about 23 A) appear in mixed systems. These could be micellar aggregates partly covered with a few cyclodextrin molecules. In addition, the results indicate rod formation (r approximately 8 A, L approximately 70 A) for the NIHG-HPCD complexes. This result is consistent with the threading of HPCDs onto NIHG750 to such an extent that the surfactant molecule takes an extended conformation at high levels of HPCD. Also, the results indicate that HPCDs may interact with the oxyethylene groups of the spherical micellar aggregates leading to an increase in micelle size and a gradual transformation to rod-shaped aggregates. The tendency to form rods increases in the order gamma-CD

Assuntos
Ciclodextrinas/química , Tensoativos/química , Modelos Teóricos , Nêutrons , Espalhamento de Radiação
19.
J Colloid Interface Sci ; 246(1): 191-202, 2002 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-16290400

RESUMO

The interaction between cyclodextrins, hydroxypropyl-beta-cyclodextrin (HPbetaCD), and hydroxypropyl-gamma-cyclodextrin (HPgammaCD) and a novel type of nonionic surfactant synthesized from a fatty acid has been investigated. The so-called nonionic heterogemini surfactant (NIHG750) contains two hydrophobic groups and two hydrophilic groups, composed of one monomethyl ethylene glycol and one secondary OH group, CH(3)(CH(2))(7)-CH[OH]-CH[O(CH(2)CH(2)O)(16)CH(3)]-(CH(2))(7)CN. Surface tension studies indicate that micelles form in NIHG750 systems in both the presence and the absence of small quantities (molar ratio (HPbetaCD:NIHG750) approximately 2) of cyclodextrin (HPbetaCD or HPgammaCD). This gives NIHG surfactants an advantage compared to single-tailed nonionic surfactants, which generally lose their ability to micellize at much lower additions of cyclodextrins. However, the interaction between HPbetaCD and NIHG750 results in a disruption of the micellar aggregates at higher levels of cyclodextrin. In the dilute systems (C(NIHG750)<0.1% (w/w) approx) prolate-shaped mixed aggregates (HPbetaCD and NIHG750) form, with a short and a long axis of the order of 8-9 and 17-20 A, respectively. These gradually aggregate into micellar-like structures at higher concentrations. In the aqueous bulk phase HPbetaCD interacts mainly with the hydrophobic part of NIHG750, but both NMR and surface tension measurements indicate that an interaction with the hydrophilic part of NIHG750, as well, may exist. This interaction results in a better packing of NIHG750 at air-water interfaces. However, at elevated temperatures results from turbidity measurements indicate that NIHG750 and HPbetaCD interact mainly through the hydrophilic part of the surfactant; a decrease in the cloud point temperature is observed. The interaction of the larger cavity molecule, HPgammaCD, with NIHG750, on the other hand, seems to be relatively weak. The interaction, when present, most probably takes place through inclusion of the hydrophilic EO part of NIHG750. The results suggest that HPgammaCD in combination with NIHG750 is a better solubilizing system than with HPbetaCD.


Assuntos
Ciclodextrinas/metabolismo , Espectroscopia de Ressonância Magnética , Tensoativos/metabolismo , Tensão Superficial
20.
J Colloid Interface Sci ; 193(2): 152-62, 1997 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-9344514

RESUMO

Two models of HEUR (hydrophobically modified ethylene oxide urethane) associative polymers (AP) are compared. The two polymers are polyethyleneoxides simply end-capped with dodecyl groups, one through an ether bond H25C12-O-(CH2CH2O)304-C12H25 (AP14, Mw = 13,700) and the other through an urethane bond H25C12-NHCOO-(CH2CH2O)304-CONH-C12H25 (AP14NCO, Mw is about the same as for AP14). The results indicate that this subtle difference in polymer architecture dramatically influences the initial association and the clouding of the polymer in water, so that AP14NCO starts to aggregate earlier but has a higher clouding temperature. However, at more elevated polymer contents (above 2-3 wt%) the differences in solution behavior and transport dynamics between the two polymers seems less significant. These conclusions are drawn through fluorescence, dynamic light scattering, NMR self-diffusion, turbidimetry, and viscosity measurements. Copyright 1997 Academic Press. Copyright 1997Academic Press

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