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1.
Helminthologia ; 58(2): 196-201, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34248380

RESUMO

We report a female Chordodes anthophorus from a Giant Asian Mantis (Hierodula membranacea) for the first time from Iran. Scanning electron microscopy (SEM) was used to describe the characters and substructures precisely. We demonstrate characteristic cuticular patterns for Chordodes anthophorus. The presence of five types of areoles including simple, tubercle, crowned and circumcluster areoles and also crowned areoles with long fi laments which is a common feature in females, confi rm our investigation.

2.
J Eur Acad Dermatol Venereol ; 31(4): 672-678, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-27184185

RESUMO

BACKGROUND: Multiple studies have noted an association between hepatitis C and psoriasis, but it is not known whether psoriasis is a result of treatment modalities for hepatitis C or a result of hepatitis C alone. OBJECTIVE: To examine the relationship between psoriasis and hepatitis C by measuring the expression of cathelicidin, TLR9 and IFNγ in psoriatic lesional and non-lesional skin in HCV-positive and negative psoriatic patients. METHODS: Two 2 mm punch biopsies of lesional and non-lesional skin in 10 patients who were HCV-negative psoriatics and seven HCV-positive psoriatics were used to measure cathelicidin, TLR9 and IFNγ mRNA expression by quantitative reverse-transcriptase polymerase chain reaction (qRT-PCR). RESULTS: The mRNA levels of cathelicidin, TLR9 and IFNγ were significantly higher in both non-lesional and lesional skin of HCV-positive patients with psoriasis as compared to HCV-negative psoriatic patients. Additionally, the IFNγ level in lesional skin of HCV-positive psoriatic patients was higher than the IFNγ level seen in non-lesional skin of those same patients. CONCLUSION: These findings suggest that HCV infection upregulates these inflammatory cytokines, possibly increasing susceptibility to developing psoriasis.


Assuntos
Peptídeos Catiônicos Antimicrobianos/genética , Hepatite C/genética , Interferon gama/genética , Psoríase/genética , RNA Mensageiro/metabolismo , Receptor Toll-Like 9/genética , Adulto , Feminino , Expressão Gênica , Hepatite C/complicações , Hepatite C/metabolismo , Humanos , Masculino , Pessoa de Meia-Idade , Psoríase/complicações , Psoríase/metabolismo , Pele/metabolismo , Catelicidinas
3.
Ann Oncol ; 27(2): 267-74, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26578731

RESUMO

BACKGROUND: Systemic chemotherapy typically converts previously unresectable liver metastases (LM) from colorectal cancer to curative intent resection in ∼15% of patients. This European multicenter phase II trial tested whether hepatic artery infusion (HAI) with triplet chemotherapy and systemic cetuximab could increase this rate to 30% in previously treated patients. PATIENTS AND METHODS: Participants had unresectable LM from wt KRAS colorectal cancer. Main non-inclusion criteria were advanced extra hepatic disease, prior HAI and grade 3 neuropathy. Irinotecan (180 mg/m(2)), oxaliplatin (85 mg/m(2)) and 5-fluorouracil (2800 mg/m(2)) were delivered via an implanted HAI access port and combined with i.v. cetuximab (500 mg/m(2)) every 14 days. Multidisciplinary decisions to resect LM were taken after every three courses. The rate of macroscopic complete resections (R0 + R1) of LM, progression-free survival (PFS) and overall survival (OS) were computed according to intent to treat. RESULTS: The patient population consisted of 42 men and 22 women, aged 33-76 years, with a median of 10 LM involving a median of six segments. Up to 3 extrahepatic lesions of <1 cm were found in 41% of the patients. A median of six courses was delivered. The primary end point was met, with R0-R1 hepatectomy for 19 of the 64 previously treated patients, 29.7% (95% confidence interval 18.5-40.9). Grade 3-4 neutropenia (42.6%), abdominal pain (26.2%), fatigue (18%) and diarrhea (16.4%) were frequent. Objective response rate was 40.6% (28.6-52.3). Median PFS and OS reached 9.3 (7.8-10.9) and 25.5 months (18.8-32.1) respectively. Those with R0-R1 hepatectomy had a median OS of 35.2 months (32.6-37.8), with 37.4% (23.6-51.2) alive at 4 years. CONCLUSION: The coordination of liver-specific intensive chemotherapy and surgery had a high curative intent potential that deserves upfront randomized testing. PROTOCOL NUMBERS: EUDRACT 2007-004632-24, NCT00852228.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Neoplasias Colorretais/tratamento farmacológico , Hepatectomia , Neoplasias Hepáticas/tratamento farmacológico , Neoplasias Hepáticas/cirurgia , Fígado/cirurgia , Adulto , Idoso , Camptotecina/análogos & derivados , Camptotecina/uso terapêutico , Cetuximab/uso terapêutico , Neoplasias Colorretais/mortalidade , Neoplasias Colorretais/patologia , Intervalo Livre de Doença , Feminino , Fluoruracila/uso terapêutico , Artéria Hepática , Humanos , Infusões Intra-Arteriais , Irinotecano , Fígado/patologia , Neoplasias Hepáticas/mortalidade , Neoplasias Hepáticas/secundário , Masculino , Pessoa de Meia-Idade , Compostos Organoplatínicos/uso terapêutico , Oxaliplatina , Proteínas Proto-Oncogênicas p21(ras)/genética , Resultado do Tratamento
4.
Allergol Immunopathol (Madr) ; 44(4): 322-30, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26803694

RESUMO

PURPOSE: The aim was to describe the clinical manifestations, complications and long-term outcome of a cohort of Iranian patients with primary immune deficiency (PID). METHOD: We retrospectively studied the demographic, clinical and immunological characteristics of the PID patients in a single tertiary centre, from January 1989 to July 2014. The patients were classified according to the International Union of Immunological Societies Expert Committee on PID. RESULTS: 98 patients were diagnosed with and followed-up for 15 disorders. The mean age at onset and diagnosis and the diagnostic delay were 8±10, 14.2±13.1 and 6.1±7 years, respectively. Parental consanguinity rate was 57%. Predominantly Antibody Deficiency was the most common diagnosis (n=63), followed by congenital defects of phagocytes (n=16), combined immunodeficiencies (n=12), well defined syndromes (n=4) and defects in innate immunity (n=3). Recurrent sinopulmonary infection was the most common presentation. Active infections were treated appropriately, in addition to prophylactic therapy with IVIG and antimicrobials. Not all the patients were compliant with prophylactic regimens due to cost and unavailability. One SCID patient underwent successful bone marrow transplantation. The total mortality rate was 19% during the follow-up period (7.8±7.6 years). The mean age of living patients at the time of study was 23±11.7 years. CONCLUSIONS: Physicians awareness of PID has been rising dramatically in Iran, ensuring an increasing number of patients being diagnosed and treated. More effective treatment services, including health insurance coverage and drug availability are needed to improve the outcome of PID patients.


Assuntos
Imunoglobulinas Intravenosas/uso terapêutico , Síndromes de Imunodeficiência , Fatores Imunológicos/uso terapêutico , Infecções Respiratórias/epidemiologia , Adolescente , Adulto , Idade de Início , Criança , Pré-Escolar , Consanguinidade , Diagnóstico Tardio , Feminino , Seguimentos , Humanos , Imunoglobulinas Intravenosas/administração & dosagem , Síndromes de Imunodeficiência/diagnóstico , Síndromes de Imunodeficiência/epidemiologia , Síndromes de Imunodeficiência/imunologia , Fatores Imunológicos/administração & dosagem , Irã (Geográfico)/epidemiologia , Masculino , Infecções Respiratórias/tratamento farmacológico , Infecções Respiratórias/etiologia , Infecções Respiratórias/prevenção & controle , Estudos Retrospectivos , Centros de Atenção Terciária/estatística & dados numéricos , Resultado do Tratamento , Adulto Jovem
5.
Mol Biol (Mosk) ; 50(2): 360-7, 2016.
Artigo em Russo | MEDLINE | ID: mdl-27239858

RESUMO

Molecular Mechanics-Generalized Born-Solvent Accessibility free energy calculations were used to analyse DNA binding affinity of 1-substituted carbazolyl-3,4-dihydro-ß-carboline molecules. In this study, DNA structure with sequence of d(CGATCG)2 was used for simulations. 15 ns molecular dynamics simulations of the studied complexes were performed. The calculated free energy was compared with experimental antitumor activity (IC(50)). The predicted free energies decreased with the increase of IC(50) values. It was shown that molecules 1-6 bind to DNA via intercalation mode, while molecules 7-9 bind through groove binding mode. Also, it was found that the vdW energy term (ΔE(vdW)) and the non-polar desolvation energy (ΔG(SA)) are the favorable terms for binding energy, whereas net electrostatic energies (ΔE(ele) + ΔG(GB)) and conformational entropy energy (TΔS) are unfavorable ones.


Assuntos
Carbolinas/química , DNA/efeitos dos fármacos , Termodinâmica , Carbolinas/metabolismo , Carbolinas/farmacologia , DNA/química , Metabolismo Energético , Simulação de Dinâmica Molecular
6.
Middle East J Anaesthesiol ; 22(4): 377-84, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25007691

RESUMO

BACKGROUND: In many countries, neuraxial blocks comprise the majority of anesthetics given for cesarean section. In Iran, however general anesthesia for cesarean section is prevalent. In our institution, the rate of general anesthesia for cesarean section is 39%, providing an opportunity to collect data regarding airway management in the parturients. We report on the outcomes of a series of patients who received general anesthesia for cesarean section. METHODS: A prospective observational study was conducted in two university hospitals, with approximately 5,500 deliveries annually. Demographics and airway characteristics were recorded. Eight potential risk factors for difficult intubation (short neck, obesity, facial edema, swollen tongue, receding mandible, and single, missing or protruding maxillary incisors) were analyzed. Then, laryngoscopic view, difficulty at intubation, and major complications were recorded. RESULTS: Data were obtained from 465 patients. There was a significant correlation between higher Mallampati score and both higher laryngoscopic view graded on the Cormack-Lehane system (P < 0.001) and difficulty at intubation (P-Value = 0.05). Emergency cesarean section was not associated with difficult intubation (P = 0.67). Multivariate analysis showed that receding mandible was the only potential risk factor for difficult tracheal intubation (P < 0.001) and removed short neck or protruding maxillary incisor which initially was powered as a risk factor by univariate analysis. A grade 3 laryngoscopic view was obtained in 15 cases (3.2%). There was no case of grade 4 view. There was only one failed intubation (0.2%), and 9 cases of very difficult intubation (1.9%). CONCLUSION: General anesthesia for cesarean section is safe with minimal risk.


Assuntos
Anestesia Geral , Cesárea , Intubação Intratraqueal/métodos , Intubação Intratraqueal/estatística & dados numéricos , Adolescente , Adulto , Feminino , Hospitais Universitários , Humanos , Irã (Geográfico) , Gravidez , Estudos Prospectivos , Fatores de Risco , Adulto Jovem
7.
Br J Cancer ; 109(6): 1543-8, 2013 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-24002595

RESUMO

BACKGROUND: Understanding their experiences of diagnosis is integral to improving the quality of care for women living with advanced/metastatic breast cancer. METHODS: A survey, initiated in March 2011, was conducted in two stages. First, the views of 47 breast cancer-related patient groups in eight European countries were sought on standards of breast cancer care and unmet needs of patients. Findings were used to develop a patient-centric survey to capture personal experiences of advanced breast cancer to determine insights into the 'trade-off' between extending overall survival and side effects associated with its treatment. The second online survey was open to women with locally advanced or metastatic breast cancer, or their carers, and responders were recruited through local patient groups. Data were collected via anonymous local language questionnaires. RESULTS: The online stage II survey received a total of 230 responses from 17 European countries: 94% of respondents had locally advanced or metastatic breast cancer and 6% were adult carers. Although the overall experience of care was generally good/excellent (77%), gaps were still perceived in terms of treatment choice and information provision. Treatment choice for patients was felt to be lacking by 32% of responders. In addition, 68% of those who responded would have liked more information about future medical treatments and research, with 57% wishing to receive this information from their oncologist. Two-thirds (66%) of women with advanced breast cancer, or their carers, believed life-extending treatment to be important so that they can spend more time with family and friends, and 67% said that the treatment was worthwhile, despite potential associated side effects. CONCLUSION: These findings show a continuing need to provide women with advanced breast cancer with better information and emphasise the importance that these patients often place on prolonging survival.


Assuntos
Neoplasias da Mama/psicologia , Avaliação das Necessidades , Satisfação do Paciente , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Coleta de Dados , Europa (Continente) , Feminino , Humanos , Pessoa de Meia-Idade , Metástase Neoplásica , Inquéritos e Questionários , Adulto Jovem
8.
J Eur Acad Dermatol Venereol ; 27(6): 771-8, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-22671985

RESUMO

BACKGROUND: Interferon-alpha (IFN-α) therapy is used to treat hepatitis C infection. The exacerbation and occurrence of psoriasis in hepatitis C patients treated with IFN-α is increasingly recognized, but the distinct associated features, aetiology and management have not been reviewed. OBJECTIVE: To review all published cases of hepatitis C patients who developed psoriasis while receiving IFN-α therapy. METHODS: The review was conducted by searching the PubMed database using the keywords 'hepatitis C' AND 'psoriasis.' In addition, references to additional publications not indexed for PubMed were followed to obtain a complete record of published data. RESULTS: We identified 32 publications describing 36 subjects who developed a psoriatic eruption while receiving IFN-α therapy for hepatitis C. Topical therapies were a commonly employed treatment modality, but led to resolution in only 30% of cases in which they were employed solely. Cessation of IFN-α therapy led to resolution in 93% of cases. Hundred per cent of those who developed psoriasis while on IFN-α therapy responded to systemic therapy and were able to continue the drug. CONCLUSION: Further studies and analysis of IFN-α-induced lesions are necessary to clarify the role of IFN-α and the hepatitis C virus in the development of psoriatic lesions.


Assuntos
Antivirais/efeitos adversos , Hepatite C/tratamento farmacológico , Interferon-alfa/efeitos adversos , Psoríase/induzido quimicamente , Adulto , Idoso , Progressão da Doença , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
9.
RSC Adv ; 13(22): 14899-14913, 2023 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-37197182

RESUMO

In this research, purification of molybdenite concentrate (MoS2) using a nitric acid leaching process was employed for the improvement of molybdenum trioxide morphology during oxidative roasting in an air atmosphere. These experiments were performed using 19 trials designed with response surface methodology and three effective parameters being temperature, time, and acid molarity. It was found that the leaching process reduced the chalcopyrite content in the concentrate by more than 95%. The influence of chalcopyrite elimination and roasting temperature on the morphology and fiber growth of the MoO3 was also investigated by SEM images. Copper plays an important role in controlling the morphology of MoO3 and its decrease led to enhancing the length of quasi-rectangular microfibers from less than 30 µm for impure MoO3 up to several centimeters for purified MoO3.

10.
Acta Trop ; 225: 106153, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34634264

RESUMO

Canine leishmaniasis (CanL) is an important parasitic e disease caused by Leishmania infantum and is transmitted by female phlebotomine sand flies primarily between canines and secondarily to humans. Recently, we showed that immunization with Leishmania major p27 gene knockout (Lmp27-/-) as a live attenuated vaccine was safe, induced immunogenicity, and protected against the development cutaneous and visceral leishmaniasis in mice. The p27 protein is a component of the COX protein complex which is responsible for ATP production. In this study, we analyzed the Lmp27-/- candidate vaccine potential with this regard to the safety and induction of immunogenicity and protection against CanL. Variables such a clinical manifestation, anti-Leishmania antibodies using direct agglutination test (DAT), lymphocyte proliferation, delayed-type hypersensitivity (DTH), bone marrow aspiration (BMA) and parasite burden using parasitological and molecular examinations were measured. The results demonstrated that the Lmp27-/- vaccinated group showed no clinical signs after inoculation with Lmp27-/- mutant during a 12-month follow-up, and had significantly higher T-cell responses (Lymphocyte proliferation and DTH), lower seroconversion and parasite burdens following a challenge inoculation with L. infantum after 6-mounth. In conclusion, vaccination with Lmp27-/- parasites would be safe and provide significant immunoprotectivity and efficacy against infection with wild type (WT) L. infantum.


Assuntos
Doenças do Cão , Leishmania infantum , Leishmania major , Vacinas contra Leishmaniose , Leishmaniose Visceral , Leishmaniose , Animais , Doenças do Cão/prevenção & controle , Cães , Feminino , Técnicas de Inativação de Genes , Leishmania infantum/genética , Leishmania major/genética , Leishmaniose Visceral/prevenção & controle , Leishmaniose Visceral/veterinária , Camundongos , Camundongos Endogâmicos BALB C
11.
J Robot Surg ; 15(4): 571-577, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32885379

RESUMO

Partial nephrectomy (PN) for small renal masses is common, but outcomes are not reported in a standard manner. Traditionally, parameters such as 90-day mortality, blood loss, transfusion rates, length of stay, nephrometry scoring and complications are published but their collective impact on warm ischemia time (WIT) and post-surgery GFR is rarely determined. Thus, our aim was to assess if "Trifecta" and "Pentafecta" outcomes could be used as useful surgical outcome markers. A prospective database of 252 Robotic-Assisted PN (RAPN) cases (2008-2019) was analysed. "Pentafecta" was defined as achievement of "Trifecta" (negative surgical margin, no postoperative complications and WIT of < 25 min) plus over 90% estimated GFR preservation and no CKD stage upgrading at 1 year. Binary logistic regression analysis was conducted to predict factors which may prevent achieving a Trifecta/Pentafecta. Median tumour size was 3 cm and mean WIT was 15 min. Positive surgical margins (PSM) occurred in 2 cases. Overall, the intra-operative complication rate was 7%. One recurrence conferred 5-year cancer-free survival of 97%. Trifecta outcome was achieved in 169 (67%) and Pentafecta in 141 (56%) of cases. At logistic regression analysis, intraoperative blood loss was the only factor to affect Trifecta achievement (p = 0.018). Advanced patient age negatively impacted Pentafecta achievement (p = 0.010). The Trifecta and Pentafecta outcomes are easily applicable to PN data, and offer an internationally comparable PN outcome, quality measure. We recommend applying this standardization to national data collection to improve the quality of reporting and ease of interpretation of surgeon/centres' outcomes.


Assuntos
Neoplasias Renais , Procedimentos Cirúrgicos Robóticos , Humanos , Neoplasias Renais/cirurgia , Recidiva Local de Neoplasia , Nefrectomia , Padrões de Referência , Estudos Retrospectivos , Procedimentos Cirúrgicos Robóticos/métodos , Resultado do Tratamento
12.
Thorac Cardiovasc Surg ; 57(4): 244-6, 2009 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-19670125

RESUMO

Soft tissue sarcomas of the chest wall, also known as primary malignant mesenchymal tumors, may be mistaken for a malignant mesothelioma because of their histologic similarities. Reports of primary pleural sarcomas are exceedingly uncommon. We present an unusual case of a primary pleural sarcoma with unique clinical and histological features not previously seen in any other subtype of pulmonary sarcoma.


Assuntos
Mesotelioma/diagnóstico por imagem , Neoplasias Pleurais/diagnóstico por imagem , Sarcoma/diagnóstico por imagem , Idoso , Diagnóstico Diferencial , Humanos , Masculino , Radiografia Torácica , Tomografia Computadorizada por Raios X
13.
Orbit ; 28(6): 337-8, 2009.
Artigo em Inglês | MEDLINE | ID: mdl-19929655

RESUMO

A new trocar has been developed that increases the ease and accuracy of Lester Jones tube placement using the Cox system in conjunctivodacryocystorhinostomy (CDCR) surgery.


Assuntos
Túnica Conjuntiva/cirurgia , Dacriocistorinostomia/métodos , Intubação/instrumentação , Ducto Nasolacrimal/cirurgia , Desenho de Equipamento , Humanos
14.
Folia Morphol (Warsz) ; 68(2): 93-7, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19449296

RESUMO

Diabetes mellitus is associated with cerebral alterations in both human and animal models of the disease. These alterations include abnormal expression of hypothalamic neuropeptides and hippocampal astrogliosis. Urtica dioica (Nettle) is among several species listed for their use against diabetes in folk medicine. The aim of this study was the evaluation of the astrocyte number in the dentate gyrus of diabetic rats after treatment with nettle. A total of 21 male albino Wistar rats were used in the present study. The animals were divided into three groups: control, nettle-untreated diabetic, and nettle treated diabetic. Hyperglycaemia was induced by streptozotocin (80 mg/kg) in the animals of the diabetic and treatment groups. One week after injection of the streptozotocin, the animals in the treatment group received a hydroalcoholic extract of Urtica dioica (100 mg/kg/day) for 4 weeks intraperitoneally. After a 5-week survival period, all the rats were sacrificed and coronal sections were taken from the dorsal hippocampal formation of the right cerebral hemispheres. The area densities of the astrocytes were measured and compared between the three groups (p < 0.05). The number of astrocytes increased in the diabetic rats (24.06 +/- 9.57) compared with the controls (17.52 +/- 6.66). The densities in the treated rats (19.50 +/- 6.16) were lower than in the diabetic rats. Furthermore, the control and treated rats showed similar densities. We concluded that U. dioica extract helped compensate for astrocytes in the treatment rats dentate gyrus in comparison with diabetic rats.


Assuntos
Astrócitos/efeitos dos fármacos , Astrócitos/patologia , Giro Denteado/efeitos dos fármacos , Giro Denteado/patologia , Diabetes Mellitus Experimental/patologia , Extratos Vegetais/farmacologia , Urtica dioica , Animais , Glicemia/metabolismo , Diabetes Mellitus Experimental/metabolismo , Hiperglicemia/metabolismo , Masculino , Ratos , Ratos Wistar , Estreptozocina
16.
Mater Sci Eng C Mater Biol Appl ; 92: 254-267, 2018 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-30184749

RESUMO

Scaffolds with gradient pore characteristics have received a great deal of attention as they can better mimic the structure of the native tissues and concurrently meet both biological and mechanical requirements. In the present study, the effects of porosity geometry and porosity gradient patterns on the deformation mechanism and compressive mechanical properties of the structures were investigated in the context of stretching (I-WP and P surfaces) versus bending dominated (D surface) triply periodic minimal surface (TPMS) based architectures. Different gradient patterns were found to significantly alter the deformation mechanism. Radial gradient patterns (perpendicular to loading direction) provide higher deformability while longitudinally graded scaffolds suffer from low failure strain. In the stretching dominated architectures vertical cracks propagated under compression due to the materials transverse expansion under compression. Deformations in the bending dominated architectures, however, were accompanied by a progressive collapse owing to the shearing of the struts. In general, stretching dominated structures showed the higher mechanical properties and provided more efficiency under mechanical loads. Finite Element simulations also demonstrated a high capability for predicting the deformation as well as mechanical responses (especially for elastic properties) and can be used as a tool for designing multifunctional gradient porous scaffolds.


Assuntos
Força Compressiva , Alicerces Teciduais/química , Simulação por Computador , Plásticos/química , Porosidade , Reprodutibilidade dos Testes , Estresse Mecânico , Propriedades de Superfície
18.
J Mech Behav Biomed Mater ; 62: 481-494, 2016 09.
Artigo em Inglês | MEDLINE | ID: mdl-27281165

RESUMO

Since the advent of additive manufacturing techniques, triply periodic minimal surfaces have emerged as a novel tool for designing porous scaffolds. Whereas scaffolds are expected to provide multifunctional performance, spatially changing pore patterns have been a promising approach to integrate mechanical characteristics of different architectures into a unique scaffold. Smooth morphological variations are also frequently seen in nature particularly in bone and cartilage structures and can be inspiring for designing of artificial tissues. In this study, we carried out experimental and numerical procedures to uncover the mechanical properties and deformation mechanisms of linearly graded porosity scaffolds for two different mathematically defined pore structures. Among TPMS-based scaffolds, P and D surfaces were subjected to gradient modeling to explore the mechanical responses for stretching and bending dominated deformations, respectively. Moreover, the results were compared to their corresponding uniform porosity structures. Mechanical properties were found to be by far greater for the stretching dominated structure (P-Surface). For bending dominated architecture (D-Surface), although there was no global fracture for uniform structures, graded structure showed a brittle fracture at 0.08 strain. A layer by layer deformation mechanism for stretching dominated structure was observed. For bending dominated scaffolds, deformation was accompanied by development of 45° shearing bands. Finite element simulations were also performed and the results showed a good agreement with the experimental observations.


Assuntos
Engenharia Tecidual , Alicerces Teciduais , Osso e Ossos , Análise de Elementos Finitos , Teste de Materiais , Porosidade
19.
Mater Sci Eng C Mater Biol Appl ; 59: 740-747, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26652428

RESUMO

In this study chitosan/halloysite nanotube composite (CS/HNT) coatings were deposited by electrophoretic deposition (EPD) on titanium substrate. Using HNT particles were investigated as new substituents for carbon nanotubes (CNTs) in chitosan matrix coatings. The ability of chitosan as a stabilizing, charging, and blending agent for HNT particles was exploited. Furthermore, the effects of pH, electrophoretic bath, and sonicating duration were studied on the deposition of suspensions containing HNT particles. Microstructure properties of coatings showed uniform distribution of HNT particles in chitosan matrix to form smooth nanocomposite coatings. The zeta potential results revealed that at pH around 3 there is an isoelectric point for HNT and it would have cathodic and anionic states at pH values less and more than 3, respectively. Therefore, CS/HNT composite deposits were produced in the pH range of 2.5 to 3. The apatite inducing ability of chitosan-HNT composite coating assigned that HNT particles were biocompatible because they formed carbonated hydroxyapatite particles on CS/HNT coating in corrected simulated body fluid (C-SBF). Finally, electrochemical corrosion characterizations determined that corrosion resistance in CS/HNT coating has been improved compared to bare titanium substrate.


Assuntos
Silicatos de Alumínio/química , Apatitas/química , Quitosana/química , Materiais Revestidos Biocompatíveis/química , Nanotubos/química , Titânio/química , Argila , Corrosão , Eletroforese
20.
J Mol Biol ; 244(5): 554-71, 1994 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-7990140

RESUMO

Calmodulin (CaM) is a calcium binding protein that regulates a wide range of enzymes. Recently the structures of a number of complexes between CaM and synthetic target peptides have been determined. The peptides correspond to the CaM-binding domain of skeletal and smooth muscle myosin light-chain kinase (MLCK) and calmodulin-dependent protein kinase II alpha. Comparison of the peptide-free and peptide-bound structures reveals that CaM undergoes a large conformational change when forming a complex, resulting in the formation of a binding surface that provides for an optimal interaction with its target. In this work, the available co-ordinates of the NMR solution structure of CaM-skeletal MLCK peptide are used as a basis upon which several molecular models of binding are built. The detailed features of the protein's peptide binding surface are revealed through two-dimensional topographical projections. Negatively charged margins at the binding surface extremities interact strongly with basic peptide residues separated by nine or ten positions. The binding surface core is hydrophobic and displays a groove with four deep pockets, which can accommodate bulky peptide residues at relative positions 4 and 8 (pocket A), 11 (pocket B), 13 (pocket C), 14 and 17 (pocket D). Therefore, both electrostatic and van der Waals' features contribute to the high affinity binding. A search for alternative peptide placements in the binding tunnel reveals the dominant role of specific electrostatic interactions in the binding energy. Apolar interactions are more permissive, such that the hydrophobic side-chains that line the binding tunnel adapt in order to maintain favourable van der Waals' contacts. The model suggests that the structure can accommodate large peptide translations (up to 5 A) and a reversed peptide binding mode, with a little loss in binding interaction energy. These calculations are compared with available experimental data, providing a structural rationale for the low sequence specificity of the CaM target recognition.


Assuntos
Calmodulina/metabolismo , Quinase de Cadeia Leve de Miosina/metabolismo , Fragmentos de Peptídeos/metabolismo , Sequência de Aminoácidos , Animais , Sítios de Ligação , Calmodulina/química , Drosophila melanogaster , Concentração de Íons de Hidrogênio , Modelos Químicos , Modelos Moleculares , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Quinase de Cadeia Leve de Miosina/química , Fragmentos de Peptídeos/química , Conformação Proteica , Alinhamento de Sequência
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