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1.
J Med Internet Res ; 22(5): e15665, 2020 05 14.
Artigo em Inglês | MEDLINE | ID: mdl-32406860

RESUMO

BACKGROUND: The medical tourism industry is currently popular in India, but there is no confirmation of the common perspectives among the country's medical travelers. OBJECTIVE: This qualitative research study analyzed web-based narratives from health travelers visiting India and described the themes of their experiences. This study aimed to answer the following primary question: What can we learn about health travelers' experiences in India from an analysis of their web-based narratives? The secondary questions were as follows: (1) What are the primary health care reasons for which patients in the examined narratives traveled to India? (2) What can be derived from the narratives regarding medical tourists' satisfaction with the outcome and result of the treatment they received in India? (3) What are some positive and negative factors influencing medical tourists' perceptions and overall experiences about their health travel to India? (4) What are the characteristics of medical tourists who write web-based narratives regarding their health experiences in India? METHODS: Publicly available narratives written by medical tourists who visited India were obtained from a Google search. The narratives included blog posts and discussion board posts by medical tourists. The analysis process consisted of initial open coding being conducted on the narratives to create initial codes and identify common themes with a focus on the primary research question and subquestions. RESULTS: Although Mumbai, Chennai, and New Delhi were not the only destination cities mentioned, these were the most popular cities patients visited for care. The medical tourists, who stated their origin country, came from one of the following continents: Africa, Europe, North America, and Oceania. Dental care, Ayurveda treatment, and eye care were the most popular types of care that medical tourists sought. The results showed that most of the medical tourists were happy with the overall experience of receiving care in India. The most popular themes with regard to the patients' satisfaction were low costs, good customer service, and services being offered that were unavailable in their home country. When negative feedback was provided, it was mainly concentrated on the overall environment of India being unorganized and unsanitary. CONCLUSIONS: Primarily, the study's findings can benefit health care providers and patients. Providers hosting medical tourists in India can use negative feedback to improve their services; similarly, providers who are losing patients to medical tourism can identify opportunities for improvement (ie, why are we losing patients). Indian providers hosting medical tourists should keep their prices competitive and continue to provide exceptional service; however, they should do their best to lessen the crowdedness of their facilities while making sure they are esthetically pleasing. Providers losing patients to medical tourism need to identify ways to ensure their services match the benefits that their international counterparts are providing, such as competitive pricing and expansion on the services provided.


Assuntos
Turismo Médico/normas , Feminino , Humanos , Índia , Internet , Masculino , Narração , Pesquisa Qualitativa
2.
BMC Biotechnol ; 18(1): 54, 2018 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-30180895

RESUMO

BACKGROUND: Switchgrass (Panicum virgatum L.) is a promising bioenergy feedstock because it can be grown on marginal land and produces abundant biomass. Recalcitrance of the lignocellulosic components of the switchgrass cell wall to enzymatic degradation into simple sugars impedes efficient biofuel production. We previously demonstrated that overexpression of OsAT10, a BAHD acyltransferase gene, enhances saccharification efficiency in rice. RESULTS: Here we show that overexpression of the rice OsAT10 gene in switchgrass decreased the levels of cell wall-bound ferulic acid (FA) in green leaf tissues and to a lesser extent in senesced tissues, and significantly increased levels of cell wall-bound p-coumaric acid (p-CA) in green leaves but decreased its level in senesced tissues of the T0 plants under greenhouse conditions. The engineered switchgrass lines exhibit an approximate 40% increase in saccharification efficiency in green tissues and a 30% increase in senesced tissues. CONCLUSION: Our study demonstrates that overexpression of OsAT10, a rice BAHD acyltransferase gene, enhances saccharification of lignocellulosic biomass in switchgrass.


Assuntos
Aciltransferases/genética , Lignina/metabolismo , Oryza/enzimologia , Panicum/genética , Panicum/metabolismo , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas/metabolismo , Aciltransferases/metabolismo , Biomassa , Parede Celular/genética , Parede Celular/metabolismo , Regulação da Expressão Gênica de Plantas , Oryza/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética
3.
Cureus ; 16(4): e58515, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38765414

RESUMO

Congenital dyserythropoietic anemias (CDAs) are rare hereditary disorders, of which type II CDA is the most common. Mutations in the SEC23B gene located on chromosome 20 result in this autosomal recessive disorder. In this case report, we present a case of CDA II with unique biopsy findings being detected via genetic testing. A female aged 30 years presented with major complaints of pallor weakness and easy fatiguability since childhood. The patient gave a history of 25 units of blood transfusion, the majority of which were transfused during pregnancy, followed by regular transfusions thereafter. On examination, all her vitals were in the normal range. Pallor, frontal bossing, and malocclusion of teeth were noted. Her laboratory workup showed the following: hemoglobin (Hb): 3.7 g/dl; mean corpuscular volume: 83 fl; mean corpuscular Hb: 29 g/dl; mean corpuscular Hb concentration: 34.9 g/dl; red cell distribution width: 30.4%; reticulocyte count (RC): 6.2%; corrected RC: 1.3%; lactate dehydrogenase: 441 IU/L; direct Coombs test/indirect Coombs test: negative; serum iron: 242 microgram/dl; transferrin saturation: 96.08%; ferritin: 1,880 ng/ml; and normal high-performance liquid chromatography and eosin-5'-maleimide binding test. The peripheral blood film showed normocytic normochromic anemia with anisopoikilocytosis in the form of a few spherocytes. No immature cells were seen. After obtaining the patient's consent, we performed a hereditary hemolytic anemia gene analysis test, which showed homozygous missense variation in exon 12 of the SEC23B gene. The bone marrow examination showed hyperplasia in the erythroid series with dyserythropoiesis, and surprisingly, myelofibrosis grade I-II (WHO 2017) was also observed on biopsy. Patients with CDA type II generally present with variable degrees of anemia along with pallor, icterus, splenomegaly, gallstones, and iron overload. In our case, the diagnosis of CDA type II was made at an adult age. Also, evidence of myelofibrosis was noted in our case, making it worth reporting. The use of a hereditary hemolytic anemia gene analysis panel test came as a rescue for its exact diagnosis. This case report emphasizes the role of molecular genetic testing for early and accurate diagnosis, which, in turn, could help in appropriate treatment planning and proper genetic counseling. The prevalence of CDA type II is still vaguely known; hence, extensive workup of persistent anemias and proper follow-up would be beneficial.

4.
J Indian Soc Pedod Prev Dent ; 42(1): 22-27, 2024 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-38616423

RESUMO

OBJECTIVE: The objective of this study was to determine the prevalence of early childhood caries in children with severe acute malnutrition (SAM) and also the hierarchy of association if any with malnutrition, anemia, and other risk factors with ECC using machine learning algorithms. METHODS: A hospital-based preventive and interventional study was conducted on SAM children (age = 2 to <6 years) who were admitted to the malnutrition treatment unit (MTU). An oral examination for early childhood caries status was done using the deft index. The anthropometric measurements and blood examination reports were recorded. Oral health education and preventive dental treatments were given to the admitted children. Three machine learning algorithms (Random Tree, CART, and Neural Network) were applied to assess the relationship between early childhood caries, malnutrition, anemia, and the risk factors. RESULTS: The Random Tree model showed that age was the most significant factor in predicting ECC with predictor importance of 98.75%, followed by maternal education (29.20%), hemoglobin level (16.67%), frequency of snack intake (9.17%), deft score (8.75%), consumption of snacks (7.1%), breastfeeding (6.25%), severe acute malnutrition (5.42%), frequency of sugar intake (3.75%), and religion at the minimum predictor importance of 2.08%. CONCLUSION: Anemia and malnutrition play a significant role in the prediction, hence in the causation of ECC. Pediatricians should also keep in mind that anemia and malnutrition have a negative impact on children's dental health. Hence, Pediatricians and Pediatric dentist should work together in treating this health problem.


Assuntos
Anemia , Cárie Dentária , Desnutrição , Desnutrição Aguda Grave , Criança , Pré-Escolar , Humanos , Suscetibilidade à Cárie Dentária , Algoritmos , Anemia/epidemiologia , Cárie Dentária/epidemiologia
5.
Cureus ; 15(7): e42133, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37476297

RESUMO

Aim This study aimed to evaluate the potential usefulness of Chat Generated Pre-Trained Transformer-3 (ChatGPT-3) in oral and maxillofacial radiology for report writing by identifying radiographic anatomical landmarks and learning about oral and maxillofacial pathologies and their radiographic features. The study also aimed to evaluate the performance of ChatGPT-3 and its usage in oral and maxillofacial radiology training. Materials and methods A questionnaire consisting of 80 questions was queried on the OpenAI app ChatGPT-3. The questions were stratified based on three categories. The categorization was based on random anatomical landmarks, oral and maxillofacial pathologies, and the radiographic features of some of these pathologies. One oral and maxillofacial radiologist evaluated queries that were answered by the ChatGPT-3 model and rated them on a 4-point, modified Likert scale. The post-survey analysis for the performance of ChatGPT-3 was based on the Strengths, Weaknesses, Opportunities, and Threats (SWOT) analysis, its application in oral and maxillofacial radiology training, and its recommended use. Results In order of efficiency, Chat GPT-3 gave 100% accuracy in describing radiographic landmarks. However, the content of the oral and maxillofacial pathologies was limited to major or characteristic radiographic features. The mean scores for the queries related to the anatomic landmarks, oral and maxillofacial pathologies, and radiographic features of the oral and maxillofacial pathologies were 3.94, 3.85, and 3.96, respectively. However, the median and mode scores were 4 and were similar to all categories. The data for the oral and maxillofacial pathologies when the questions were not specifically included in the format of the introduction of the pathology, causes, symptoms, and treatment. Out of two abbreviations, one was not answered correctly. Conclusion The study showed that ChatGPT-3 is efficient in describing the pathology, characteristic radiographic features, and describing anatomical landmarks. ChatGPT-3 can be used as an adjunct when an oral radiologist needs additional information on any pathology, however, it cannot be the mainstay for reference. ChatGPT-3 is less detail-oriented, and the data has a risk of infodemics and the possibility of medical errors. However, Chat GPT-3 can be an excellent tool in helping the community in increasing the knowledge and awareness of various pathologies and decreasing the anxiety of the patients while dental healthcare professionals formulate an appropriate treatment plan.

6.
Indian Pediatr ; 60(5): 394-396, 2023 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-36814120

RESUMO

OBJECTIVES: This prospective observational study aimed to identify the current trend of the circulating viral strains responsible for HFMD outbreak in four tertiary care centers in Rajasthan, amidst the COVID-19 pandemic (April-October 2022). METHODS: Cases with suspected HFMD, presenting to our skin outpatient department were assessed clinically and serologically (IgM antibodies against coxsackie virus (CV) A6, A16 and enterovirus 71) for evidence of the disease. RESULTS: We identified 718 new HFMD patients (161 adults) with peaks in May and August, 2022. Male:female ratio decreased with increasing age. Most children were asymptomatic. A total of 385/409 patients assessed serologically, were found positive, most commonly against CV-A6. CONCLUSION: Though HFMD typically affects young children, an unusually higher proportion of adults were affected during the current pandemic. There were some subtle differences between pediatric and adult presentation of HFMD.


Assuntos
COVID-19 , Doença de Mão, Pé e Boca , Doenças da Boca , Adulto , Humanos , Criança , Masculino , Feminino , Lactente , Pré-Escolar , SARS-CoV-2 , Pandemias , COVID-19/epidemiologia , Índia/epidemiologia , Doença de Mão, Pé e Boca/epidemiologia , Anticorpos Antivirais , Surtos de Doenças , Doenças da Boca/epidemiologia , China/epidemiologia
7.
Artigo em Inglês | MEDLINE | ID: mdl-36429824

RESUMO

Adolescents from minority groups are particularly susceptible to poor oral hygiene behaviors, including lack of daily flossing. This cross-sectional study aimed to conduct an exploratory behavioral research to identify evidence-based (theory-based) approaches to promote flossing behavior among African American/Black and Latinx/Hispanic (minority) adolescents. A 39-item psychometrically valid web-based questionnaire was used to collect responses from a nationwide sample of minority adolescents aged 10-17 years residing in the United States. The data were analyzed using bivariate and multivariate statistical methods. Of 520 minority adolescents (260 African American/Black and 260 Latinx/Hispanic adolescents), the proportion of flossing was nearly equally split in the sample. A significantly higher proportion of minority adolescents who were flossing had access to floss as opposed to those who were not flossing (86.8% vs. 69.8%, p < 0.001). A significantly higher proportion of minority adolescents who were not flossing did not visit the dentist over the past year as opposed to those who floss (25.2% vs. 14.7%, p < 0.001). Among the participants who were not flossing, gender, grade level, instruction in school regarding flossing, and multi-theory model (MTM) of health behavior change constructs were the significant predictors (p < 0.001) of initiating and sustaining flossing. The findings of this study will serve as baseline data for developing and evaluating effective evidence-based interventions using the MTM.


Assuntos
Comportamentos Relacionados com a Saúde , Grupos Minoritários , Adolescente , Estados Unidos , Humanos , Estudos Transversais , População Negra , Hispânico ou Latino
8.
Plant Mol Biol ; 77(4-5): 391-406, 2011 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-21887580

RESUMO

Efficient and cost-effective conversion of plant biomass to usable forms of energy requires a thorough understanding of cell wall biosynthesis, modification and degradation. To elucidate these processes, we assessed the expression dynamics during enzymatic removal and regeneration of rice cell walls in suspension cells over time. In total, 928 genes exhibited significant up-regulation during cell wall removal, whereas, 79 genes were up-regulated during cell wall regeneration. Both gene sets are enriched for kinases, transcription factors and genes predicted to be involved in cell wall-related functions. Integration of the gene expression datasets with a catalog of known and/or predicted biochemical pathways from rice, revealed metabolic and hormonal pathways involved in cell wall degradation and regeneration. Rice lines carrying Tos17 mutations in genes up-regulated during cell wall removal exhibit dwarf phenotypes. Many of the genes up-regulated during cell wall development are also up-regulated in response to infection and environmental perturbations indicating a coordinated response to diverse types of stress.


Assuntos
Parede Celular/genética , Oryza/genética , Proteínas de Plantas/genética , Parede Celular/metabolismo , Parede Celular/ultraestrutura , Células Cultivadas , Perfilação da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Lignina/biossíntese , Mutação , Oryza/metabolismo , Oryza/ultraestrutura , Pectinas/biossíntese , Fenótipo , Proteínas de Plantas/metabolismo , Proteínas de Plantas/fisiologia , Polissacarídeos/biossíntese , Estresse Fisiológico/genética , Transcrição Gênica
9.
Health Promot Perspect ; 11(4): 460-466, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-35079591

RESUMO

Background: Researchers use multiple approaches to engage and maintain underrepresented populations in research. They often overlook integrated marketing communication (IMC), a useful approach for commercial marketing, for more established health promotion and social marketing techniques. There is limited information on the application of the IMC approach for recruiting and retaining African American study participants. This article explores the IMC approach used to recruit and retain volunteers for a community-based intervention. Methods: This is a cross-sectional study relying on extracted data from the Multi-Theory Model (MTM) of Health Behavior Physical Activity intervention. A brief multiple-choice survey was administered to a sample of African American women (n=74) to assess the effectiveness of applying an IMC approach for recruiting and retaining volunteers for the multi-week program during January - June 2018. The measures were (1) source for study information, (2) preferred method of contact, (3) primary source for health information. Results: Sixty-nine women listed their doctor as the primary source of health information and five women in the age group 18-34 identified social media (n=3) and websites (n=2). Age is significantly related to the preference of communication tools used to recruit and retain the African American participants. A statistical significance (P =0.025) suggests for women ages 51-69, a combination of radio, church, and word of mouth was more effective for recruitment. The older women preferred telephone calls compared to the women ages 18-50 who relied on texting. Conclusion: IMC can synergize individual communication elements in a coordinated manner to address niche audiences and develop cost-effective health communications programs that can improve recruitment and retention efforts in minority populations.

10.
Int J Adolesc Med Health ; 33(5)2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-32007946

RESUMO

OBJECTIVE: The present study aimed at determining predictors of sleep behaviour change among dental students using the multi-theory model (MTM) of health behaviour change in India. METHODS: This study was conducted among 535 students of a dental college in India. Predictors of sleep behaviour change were assessed using a validated 30-item questionnaire. Theoretical predictors of sleep behaviour were modelled using multiple linear regression. RESULTS: The response rate was 95.10%. A total of 449 of 535 students filled in the form, out of which 127 (28.30%) were inadequate sleepers. Inadequate sleep behaviour showed a strong preponderance within the male population (81.9%). The percentage of inadequate sleepers was highest in second year undergraduates and those obtaining between 60 and 69.9% marks in previous exams. For the initiation model, the standardised regression coefficients (ß) for the three constructs - participatory dialogue, behavioural confidence and change in physical environment were 0.050 [p = 0.579, 95% (confidence interval)CI: -0.039 to 0.070], 0.213 (p = 0.019, 95% CI: 0.029-0.320) and 0.062 (p = 0.496, 95% CI: -0.073 to 0.149), respectively. For the sustenance model, ß for emotional transformation, practice for change and changes in social environment was 0.192 (p = 0.047, 95% CI: 0.002-0.250), 0.175 (p = 0.091, 95% CI: -0.024 to 0.318) and 0.046 (p = 0.623, 95% CI: -0.094 to 0.157), respectively. CONCLUSION: Improving behavioural confidence and bringing about emotional transformation were significant predictors for a reduction in inadequate sleep behaviour in dental students. Working on these predictors may improve sleep behaviours in dental students.

11.
ACS Synth Biol ; 9(3): 475-485, 2020 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-32105449

RESUMO

Engineered living materials have the potential for wide-ranging applications such as biosensing and treatment of diseases. Programmable cells provide the functional basis for living materials; however, their release into the environment raises numerous biosafety concerns. Current designs that limit the release of genetically engineered cells typically involve the fabrication of multilayer hybrid materials with submicrometer porous matrices. Nevertheless the stringent physical barriers limit the diffusion of macromolecules and therefore the repertoire of molecules available for actuation in response to communication signals between cells and their environment. Here, we engineer a novel living material entitled "Platform for Adhesin-mediated Trapping of Cells in Hydrogels" (PATCH). This technology is based on engineered E. coli that displays an adhesion protein derived from an Antarctic bacterium with a high affinity for glucose. The adhesin stably anchors E. coli in dextran-based hydrogels with large pore diameters (10-100 µm) and reduces the leakage of bacteria into the environment by up to 100-fold. As an application of PATCH, we engineered E. coli to secrete the bacteriocin lysostaphin which specifically kills Staphyloccocus aureus with low probability of raising antibiotic resistance. We demonstrated that living materials containing this lysostaphin-secreting E. coli inhibit the growth of S. aureus, including the strain resistant to methicillin (MRSA). Our tunable platform allows stable integration of programmable cells in dextran-based hydrogels without compromising free diffusion of macromolecules and could have potential applications in biotechnology and biomedicine.


Assuntos
Adesinas Bacterianas/metabolismo , Materiais Biocompatíveis/farmacologia , Escherichia coli/genética , Engenharia Genética/métodos , Lisostafina/farmacologia , Adesinas Bacterianas/genética , Antibacterianos/metabolismo , Antibacterianos/farmacologia , Materiais Biocompatíveis/metabolismo , Membrana Celular/metabolismo , Dextranos/química , Escherichia coli/metabolismo , Hidrogéis/química , Hidrogéis/metabolismo , Lisostafina/genética , Lisostafina/metabolismo , Marinomonas/genética , Teste de Materiais , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos
12.
Asian J Psychiatr ; 43: 101-104, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31121535

RESUMO

Today, clinicians and researchers believe that mood disorders in children and adolescents remain one of the most under diagnosed mental health problems. Mood disorders in adolescents also put them at risk for other conditions that may persist long after the initial episodes of depression are resolved. In our study we have assessed the mood state spectrum of a person over the time and validated the same by correlating with salivary cortisol, psychologist assessment results. METHODS AND MATERIALS: Images from the training dataset are classified according to one among the nine emotions. The Images that are classified accordingly are taken as training set and a suitable convolutional neural network is trained/retrained for this data. The mean values predicted moods are considered as input for another model that predicts higher the stress level. RESULTS: With the inception v3 trained for 1,00,000 times with the data set that's close to 12,000 images classified accordingly to the nine emotion classes as specified by psychologist the model was able to obtain 78.4% of testing accuracy while with the near perfect training accuracy. CONCLUSION: The mood analysis was conclusively helpful in the estimation of the negative emotion parameter as close to the values that are obtained by with Depression, Anxiety and stress scale (DASS21) the mood analysis. The salivary cortisol as unbiased variable correlating with DASS 21 score could have a potential uses in early detection of mood disorder and correction. This platform will be helping the subject as a early mood screening tool.


Assuntos
Afeto/fisiologia , Ansiedade/diagnóstico , Depressão/diagnóstico , Face , Hidrocortisona/metabolismo , Redes Neurais de Computação , Reconhecimento Automatizado de Padrão , Adulto , Ansiedade/metabolismo , Ansiedade/fisiopatologia , Depressão/metabolismo , Depressão/fisiopatologia , Humanos , Masculino , Aplicativos Móveis , Monitorização Ambulatorial , Monitorização Neurofisiológica , Escalas de Graduação Psiquiátrica , Saliva
13.
J Res Health Sci ; 17(1): e00370, 2017 02 25.
Artigo em Inglês | MEDLINE | ID: mdl-28413165

RESUMO

BACKGROUND: A substantial proportion of college students to not drink enough water and consume sugar-sweetened beverages (SSBs). Consumption of SSBs is associated with weight gain, obesity, type 2 diabetes mellitus, dental carries, and increased risk for cardiovascular disease. Hence, the purpose of this study was to use the multi-theory model (MTM) in predicting initiation and sustenance of plain water consumption instead of sugar-sweetened beverages among college students. STUDY DESIGN: A cross-sectional study. METHODS: In this cross-sectional study, a 37-item valid and reliable MTM-based survey was administered to college students in 2016 via Qualtrics at a large public university in the Southeastern United States. Overall, 410 students responded to the survey; of those, 174 were eligible for the study and completed it. RESULTS: Stepwise multiple regression analysis revealed that 61.8% of the variance in the initiation of drinking plain water instead of SSBs was explained by behavioral confidence (P<0.001) and changes in the physical environment (P<0.001). Further, 58.3% of the variance in the sustenance of drinking plain water instead of SSBs was explained by emotional transformation (P<0.001) and practice for change (P=0.001). CONCLUSIONS: Multi-theory model of health behavior change is a robust theory for predicting plain water consumption instead of SSBs in college students. Interventions should be developed based on this theory for this target population.


Assuntos
Bebidas , Sacarose Alimentar/administração & dosagem , Ingestão de Líquidos , Comportamento Alimentar , Comportamentos Relacionados com a Saúde , Modelos Biológicos , Água/administração & dosagem , Estudos Transversais , Cárie Dentária/prevenção & controle , Diabetes Mellitus Tipo 2/prevenção & controle , Emoções , Meio Ambiente , Comportamento Alimentar/psicologia , Feminino , Humanos , Intenção , Masculino , Obesidade/prevenção & controle , Teoria Psicológica , Autoeficácia , Sudeste dos Estados Unidos , Edulcorantes/administração & dosagem , Pensamento , Adulto Jovem
14.
Langmuir ; 23(13): 7101-12, 2007 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-17511484

RESUMO

Membrane proteins are some of the most sophisticated molecules found in nature. These molecules have extraordinary recognition properties; hence, they represent a vast source of specialized materials with potential uses in sensing and screening applications. However, the strict requirement of the native lipid environment to preserve their structure and functionality presents an impediment in building biofunctional materials from these molecules. In general, the purification protocols remove the native lipid support structures found in the cellular environment that stabilize the membrane proteins. Furthermore, the membrane protein structure is often highly complex, typified by large, multisubunit complexes that not only span the lipid bilayer but also contain large (>2 nm) cytoplasmic and extracellular domains that protrude from the membrane. The present study is focused on using a biomimetic approach to build a stable, fluid microenvironment to be used to incorporate larger membrane proteins of interest into a tether-supported lipid bilayer membrane adequately spaced above a substrate passivated to liposome fusion and nonspecific adsorption. Our aim is to reintroduce the supporting structures of the native cell membrane using self-assembled supramolecular complexes constructed on microspheres in an artificial cytoskeleton motif. Central to our architecture is to utilize bacteriorhodopsin (bR), a transmembrane protein, as a biomembrane anchoring molecule to be tethered to surfaces of interest as a sparse structural element in the design. Compared to a typical lipid tether, which inserts into one leaflet of the lipid bilayer, bR anchoring provides an over 8-fold greater hydrophobic surface area in contact with the bilayer. In the work presented here, the silica microsphere surface was biofunctionalized with streptavidin to make it a suitable supporting interface. This was achieved by self-assembly of (p-aminophenyl)trimethoxysilane on the silica surface followed by subsequent conjugation of biotin-PEG3400 (PEG = poly(ethylene glycol) and PEG2000 for further passivation and the binding of streptavidin. We have conjugated bR with biotin-PEG3400 through amine-based coupling to use it as a tether. The biotin-PEG-bR conjugate was further labeled with Texas Red to facilitate localization via fluorescence imaging. Confocal microscopy was utilized to analyze the microsphere surface at different stages of surface modification by employing fluorescent staining techniques. Sparely tethered supported lipid bilayer membranes were constructed successfully on streptavidin-functionalized silica particles (5 mum) using a detergent-based method in which tethered bR nucleates self-assembly of the bilayer membrane. The fluidity of the supported membranes was analyzed using fluorescence recovery after photobleaching in confocal imaging detection mode. The phospholipid diffusion coefficients obtained from these studies indicated that nativelike fluidity was achieved in the tether-supported membranes, thus providing a prospective microenvironment for insertion of membrane proteins of interest.


Assuntos
Bacteriorodopsinas/química , Materiais Biomiméticos/química , Halobacterium salinarum/química , Bicamadas Lipídicas/química , Microesferas , Dióxido de Silício/química , Biotina/química , Interações Hidrofóbicas e Hidrofílicas , Polietilenoglicóis/química , Silanos/química , Estreptavidina/química
15.
Langmuir ; 22(12): 5403-11, 2006 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-16732670

RESUMO

Here, we describe a protocol to bind individual, intact phospholipid bilayer liposomes, which are on the order of 1 microm in diameter, in microwells etched in a regular array on a silicon oxide substrate. The diameter of the wells is on the order of the liposome diameter, so only one liposome is located in each well. The background of the silicon oxide surface is functionalized with a PEG oligomer using the contact printing of a PEG silane to present a surface that resists the adsorption of proteins, lipid material, and liposomes. The interiors of the wells are functionalized with an aminosilane to facilitate the conjugation of biotin, which is then bound to Neutravidin. The avidin-coated well interiors bind the liposomes whose surfaces contain biotinylated lipids. The specific binding of the liposomes to the surface using the biotin-avidin linkage, together with the resistant nature of the background and the physical confinement of the wells, allows the liposomes to remain intact and to not unravel, rupture, and fuse onto the surface. We demonstrate this intact arraying using confocal laser scanning microscopy of fluorophores specifically tagging the microwells, the lipid bilayer, and the aqueous interior of the liposome.


Assuntos
Bicamadas Lipídicas/química , Lipossomos/química , Técnicas Analíticas Microfluídicas , Avidina/química , Biotina/química , Microscopia Confocal , Polietilenoglicóis/química , Dióxido de Silício
16.
Bioconjug Chem ; 15(4): 942-7, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15264886

RESUMO

The sophistication of supported lipid bilayer membranes has increased steadily as new applications are being explored. In general, tethered lipids are used to anchor the lipid bilayer to the substrate. Here we describe a new type of anchoring system for supported lipid bilayers that is based on biotin-PEG3400-bacteriorhodopsin conjugates. Amine-based coupling was used to construct the polymer conjugates, followed by fluorophore labeling to enable confocal imaging. The bacteriorhodopsin-based anchoring system was used to construct solid-supported vesicles from streptavidin-coated microspheres. This method could provide a new route for the stability enhancement of supported lipid bilayer membrane assemblies.


Assuntos
Bacteriorodopsinas/química , Bicamadas Lipídicas/química , Sequência de Aminoácidos , Bacteriorodopsinas/farmacologia , Membrana Celular/química , Membrana Celular/efeitos dos fármacos , Lipossomos/química , Lisina/química , Microscopia Confocal , Microesferas , Dados de Sequência Molecular , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz , Estreptavidina/química
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