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1.
JMIR Res Protoc ; 6(7): e147, 2017 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-28754653

RESUMO

BACKGROUND: The potential of technology to aid integration of care delivery systems is being explored in a range of contexts across a variety of conditions in the United Kingdom. Prostate cancer is the most common cancer in UK men. With a 10-year survival rate of 84%, there is a need to explore innovative methods of care that are integrated between primary health care providers and specialist teams in order to address long-term consequences of the disease and its treatment as well as to provide continued monitoring for recurrence. OBJECTIVE: Our aim was to test the feasibility of a randomized controlled trial to compare a model of prostate cancer continuing and follow-up care integration, underpinned by digital technology, with usual care in terms of clinical and cost-effectiveness, patient-reported outcomes, and experience. METHODS: A first phase of the study has included development of an online adaptive prostate specific Holistic Needs Assessment system (HNA), training for primary care-based nurses, training of an IT peer supporter, and interviews with health care professionals and men with prostate cancer to explore views of their care, experience of technology, and views of the proposed intervention. In Phase 2, men in the intervention arm will complete the HNA at home to help identify and articulate concerns and share them with their health care professionals, in both primary and specialist care. Participants in the control arm will receive usual care. Outcomes including quality of life and well-being, prostate-specific concerns, and patient enablement will be measured 3 times over a 9-month period. RESULTS: Findings from phase 1 indicated strong support for the intervention among men, including those who had had little experience of digital technology. Men expressed a range of views on ways that the online system might be used within a clinical pathway. Health care professionals gave valuable feedback on how the output of the assessment might be presented to encourage engagement and uptake by clinical teams. Recruitment to the second phase of the study, the feasibility trial, commenced March 2017. CONCLUSIONS: To our knowledge, this study is the first in the United Kingdom to trial an online holistic needs assessment for men with prostate cancer, with data shared between patients and primary and secondary care providers. This study addresses recommendations in recent policy documents promoting the importance of data sharing and enhanced communication between care providers as a basis for care integration. We anticipate that this model of care will ultimately provide important benefits for both patients and the National Health Service. TRIAL REGISTRATION: International Standard Randomized Controlled Trial Number (ISRCTN): 31380482; http://www.isrctn.com/ISRCTN31380482 (Archived by WebCite at http://www.webcitation.org/6s8I42u5N).

2.
Exp Dermatol ; 23(1): 39-44, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24372651

RESUMO

Plant-derived oils consisting of triglycerides and small amounts of free fatty acids (FFAs) are commonly used in skincare regimens. FFAs are known to disrupt skin barrier function. The objective of this study was to mechanistically study the effects of FFAs, triglycerides and their mixtures on skin barrier function. The effects of oleic acid (OA), glyceryl trioleate (GT) and OA/GT mixtures on skin barrier were assessed in vivo through measurement of transepidermal water loss (TEWL) and fluorescein dye penetration before and after a single application. OA's effects on stratum corneum (SC) lipid order in vivo were measured with infrared spectroscopy through application of perdeuterated OA (OA-d34 ). Studies of the interaction of OA and GT with skin lipids included imaging the distribution of OA-d34 and GT ex vivo with IR microspectroscopy and thermodynamic analysis of mixtures in aqueous monolayers. The oil mixtures increased both TEWL and fluorescein penetration 24 h after a single application in an OA dose-dependent manner, with the highest increase from treatment with pure OA. OA-d34 penetrated into skin and disordered SC lipids. Furthermore, the ex vivo IR imaging studies showed that OA-d34 permeated to the dermal/epidermal junction while GT remained in the SC. The monolayer experiments showed preferential interspecies interactions between OA and SC lipids, while the mixing between GT and SC lipids was not thermodynamically preferred. The FFA component of plant oils may disrupt skin barrier function. The affinity between plant oil components and SC lipids likely determines the extent of their penetration and clinically measurable effects on skin barrier functions.


Assuntos
Epiderme/efeitos dos fármacos , Epiderme/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Óleos de Plantas/farmacologia , Adulto , Água Corporal/efeitos dos fármacos , Água Corporal/metabolismo , Fármacos Dermatológicos/química , Fármacos Dermatológicos/farmacocinética , Fármacos Dermatológicos/farmacologia , Feminino , Humanos , Técnicas In Vitro , Microespectrofotometria , Ácido Oleico/farmacocinética , Ácido Oleico/farmacologia , Óleos de Plantas/química , Óleos de Plantas/farmacocinética , Absorção Cutânea/efeitos dos fármacos , Absorção Cutânea/fisiologia , Trioleína/farmacocinética , Trioleína/farmacologia , Adulto Jovem
3.
J Biomed Opt ; 17(9): 96009-1, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23085910

RESUMO

Infrared microscopic imaging has been utilized to analyze for the first time the spatial distribution of lipid structure in an ex vivo human organ culture skin wound healing model. Infrared images were collected at zero, two, four, and six days following wounding. Analysis of lipid infrared spectral properties revealed the presence of a lipid class with disordered chains within and in the vicinity of the migrating epithelial tongue. The presence of lipid ester C=O bands colocalized with the disordered chains provided evidence for the presence of carbonyl-containing lipid species. Gene array data complemented the biophysical studies and provided a biological rationale for the generation of the disordered chain species. This is the first clear observation, to our knowledge, of disordered lipid involvement in cutaneous wound healing. Several possibilities are discussed for the biological relevance of these observations.


Assuntos
Metabolismo dos Lipídeos/fisiologia , Microscopia/métodos , Pele/lesões , Pele/metabolismo , Cicatrização/fisiologia , Ferimentos Penetrantes/metabolismo , Células Epiteliais/metabolismo , Humanos , Técnicas In Vitro , Raios Infravermelhos , Pele/patologia , Ferimentos Penetrantes/patologia
4.
Biopolymers ; 95(9): 607-15, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21394716

RESUMO

Water is an integral part of collagen's triple helical and higher order structure. Studies of model triple helical peptides have revealed the presence of repetitive intrachain, interchain, and intermolecular water bridges (Bella et al., Structure 1995, 15, 893-906). In addition, an extended cylinder of hydration is thought to be responsible for collagen fiber assembly. Confocal Raman spectroscopy and dynamic vapor sorption (DVS) measurements of human Type I collagen and pigskin dermis were performed to probe relative humidity (RH)-dependent differences in the nature and level of collagen hydration. Raman spectra were also acquired as a function of time for both Type I collagen and pigskin dermis samples upon exchange of a 100% RH H(2) O to deuterium oxide (D(2) O) environment. Alterations in Amide I and III modes were consistent with anticipated changes in hydrogen bonding strength as RH increased and upon H → D exchange. Of note is the identification of a Raman spectral marker (band at 938 cm(-1) ) which appears to be sensitive to alterations in collagen-bound water. Analysis of DVS isotherms provided a quantitative measure of adsorbed and absorbed water vapor consistent with the Raman results. The development of a Raman spectral marker of collagen hydration in intact tissue is relevant to diverse fields of study ranging from the evaluation of therapeutics for wound healing to hydration of aging skin.


Assuntos
Colágeno Tipo I/química , Colágeno/química , Derme/metabolismo , Análise Espectral Raman/métodos , Adsorção , Animais , Biópsia , Óxido de Deutério/química , Humanos , Umidade , Ligação de Hidrogênio , Microscopia Confocal/métodos , Modelos Químicos , Conformação Proteica , Suínos , Água/química
5.
Ophthalmic Surg Lasers Imaging ; : 1-3, 2010 Mar 09.
Artigo em Inglês | MEDLINE | ID: mdl-20337303

RESUMO

A case of a Descemet's membrane detachment (DMD) caused by the inadvertent intracorneal injection of sodium hyaluronate was presented. This was concluded after chemical analysis of a viscous substance found in a patient's cornea showed to be a breakdown product of sodium hyaluronate. Surgical correction of the detachment included removing the viscous substance and tamponading the detachment with an air bubble. Although other gases such as sulfur hexafluoride (SF6) provide longer means of tamponade, they have increased postoperative risks like glaucoma associated with their use. Air can provide an effective means of tamponade with minimal postoperative risks.

6.
Cancer Res ; 67(20): 9771-80, 2007 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-17942907

RESUMO

Golgi beta1,6N-acetylglucosaminyltransferase V (Mgat5) produces beta1,6GlcNAc-branched complex N-glycans on cell surface glycoproteins that bind to galectins and promote surface residency of glycoproteins, including cytokine receptors. Carcinoma cells from polyomavirus middle T (PyMT) transgenic mice on a Mgat5-/- background have reduced surface levels of epidermal growth factor (EGF) and transforming growth factor-beta (TGF-beta) receptors and are less sensitive to acute stimulation by cytokines in vitro compared with PyMT Mgat5+/+ tumor cells but are nonetheless tumorigenic when injected into mice. Here, we report that PyMT Mgat5-/- cells are reduced in size, checkpoint impaired, and following serum withdrawal, fail to down-regulate glucose transport, protein synthesis, reactive oxygen species (ROS), and activation of Akt and extracellular signal-regulated kinase. To further characterize Mgat5+/+ and Mgat5-/- tumor cells, a screen of pharmacologically active compounds was done. Mgat5-/- tumor cells were comparatively hypersensitive to the ROS inducer 2,3-dimethoxy-1,4-naphthoquinone, hyposensitive to tyrosine kinase inhibitors, to Golgi disruption by brefeldin A, and to mitotic arrest by colcemid, hydroxyurea, and camptothecin. Finally, regulation of ROS, glucose uptake, and sensitivities to EGF and TGF-beta were rescued by Mgat5 expression or by hexosamine supplementation to complex N-glycan biosynthesis in Mgat5-/- cells. Our results suggest that complex N-glycans sensitize tumor cells to growth factors, and Mgat5 is required to balance responsiveness to growth and arrest cues downstream of metabolic flux.


Assuntos
Neoplasias Mamárias Experimentais/metabolismo , Polissacarídeos/metabolismo , Animais , Antígenos Transformantes de Poliomavirus/genética , Processos de Crescimento Celular/fisiologia , Linhagem Celular Tumoral , Glucose/metabolismo , Complexo de Golgi/enzimologia , Sistema de Sinalização das MAP Quinases , Neoplasias Mamárias Experimentais/enzimologia , Neoplasias Mamárias Experimentais/genética , Neoplasias Mamárias Experimentais/patologia , Camundongos , Camundongos Transgênicos , Mitocôndrias/metabolismo , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , N-Acetilglucosaminiltransferases/genética , N-Acetilglucosaminiltransferases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Uridina Difosfato N-Acetilglicosamina/metabolismo
7.
J Control Release ; 123(2): 141-7, 2007 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-17826862

RESUMO

Polyphenolic resveratrol has been identified as a potent antioxidant acting as both a free radical scavenger and an inhibitor of enzyme oxidative activity. However, the reactive propensity of resveratrol also limits its use in topical formulations. A transient derivative of resveratrol, resveratrol triphosphate, has been designed to provide a means for the delayed delivery of the active compound in skin tissue where endogenous enzymes capable of dephosphorylation reside. Confocal Raman microscopy studies of intact pigskin biopsies treated with modified resveratrol provided information about the spatial distribution and time-dependence of permeation and conversion to the native active form. Conversion to the active form was not observed when skin samples were exposed to steam, a procedure that likely inactivates endogenous skin enzymes. In addition, treatment with the triphosphate compared to the parent compound revealed a more homogeneous distribution of resveratrol throughout the stratum corneum and viable epidermis when the former was applied. Thus, the bioavailability of resveratrol in the epidermis appears to be enhanced upon application of the pro-molecule compared to resveratrol.


Assuntos
Antioxidantes/metabolismo , Microscopia Confocal , Organofosfatos/metabolismo , Pró-Fármacos/metabolismo , Absorção Cutânea , Pele/metabolismo , Análise Espectral Raman , Estilbenos/metabolismo , Administração Cutânea , Animais , Antioxidantes/administração & dosagem , Antioxidantes/química , Disponibilidade Biológica , Química Farmacêutica , Cultura em Câmaras de Difusão , Composição de Medicamentos , Hidrólise , Organofosfatos/administração & dosagem , Organofosfatos/química , Permeabilidade , Fosforilação , Pró-Fármacos/administração & dosagem , Pró-Fármacos/química , Pele/enzimologia , Estilbenos/administração & dosagem , Estilbenos/química , Suínos , Fatores de Tempo
8.
J Am Chem Soc ; 129(25): 7877-84, 2007 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-17550251

RESUMO

X-ray crystallography of collagen model peptides has provided high-resolution structures of the basic triple-helical conformation and its water-mediated hydration network. Vibrational spectroscopy provides a useful bridge for transferring the structural information from X-ray diffraction to collagen in its native environment. The vibrational mode most useful for this purpose is the amide I mode (mostly peptide bond C=O stretch) near 1650 cm-1. The current study refines and extends the range of utility of a novel simulation method that accurately predicts the infrared (IR) amide I spectral contour from the three-dimensional structure of a protein or peptide. The approach is demonstrated through accurate simulation of the experimental amide I contour in solution for both a standard triple helix, (Pro-Pro-Gly)10, and a second peptide with a Gly --> Ala substitution in the middle of the chain that models the effect of a mutation in the native collagen sequence. Monitoring the major amide I peak as a function of temperature gives sharp thermal transitions for both peptides, similar to those obtained by circular dichroism spectroscopy, and the Fourier transform infrared (FTIR) spectra of the unfolded states were compared with polyproline II. The simulation studies were extended to model early stages of thermal denaturation of (Pro-Pro-Gly)10. Dihedral angle changes suggested by molecular dynamics simulations were made in a stepwise fashion to generate peptide unwinding from each end, which emulates the effect of increasing temperature. Simulated bands from these new structures were then compared to the experimental bands obtained as temperature was increased. The similarity between the simulated and experimental IR spectra lends credence to the simulation method and paves the way for a variety of applications.


Assuntos
Colágeno/química , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Colágeno/genética , Colágeno/metabolismo , Conformação Proteica , Dobramento de Proteína , Temperatura
9.
J Biol Chem ; 282(27): 20027-35, 2007 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-17488719

RESUMO

Autoimmunity is a complex trait disease where the environment influences susceptibility to disease by unclear mechanisms. T cell receptor clustering and signaling at the immune synapse, T cell proliferation, CTLA-4 endocytosis, T(H)1 differentiation, and autoimmunity are negatively regulated by beta1,6GlcNAc-branched N-glycans attached to cell surface glycoproteins. Beta1,6GlcNAc-branched N-glycan expression in T cells is dependent on metabolite supply to UDP-GlcNAc biosynthesis (hexosamine pathway) and in turn to Golgi N-acetylglucosaminyltransferases Mgat1, -2, -4, and -5. In Jurkat T cells, beta1,6GlcNAc-branching in N-glycans is stimulated by metabolites supplying the hexosamine pathway including glucose, GlcNAc, acetoacetate, glutamine, ammonia, or uridine but not by control metabolites mannosamine, galactose, mannose, succinate, or pyruvate. Hexosamine supplementation in vitro and in vivo also increases beta1,6GlcNAc-branched N-glycans in naïve mouse T cells and suppresses T cell receptor signaling, T cell proliferation, CTLA-4 endocytosis, T(H)1 differentiation, experimental autoimmune encephalomyelitis, and autoimmune diabetes in non-obese diabetic mice. Our results indicate that metabolite flux through the hexosamine and N-glycan pathways conditionally regulates autoimmunity by modulating multiple T cell functionalities downstream of beta1,6GlcNAc-branched N-glycans. This suggests metabolic therapy as a potential treatment for autoimmune disease.


Assuntos
Autoimunidade , Diabetes Mellitus Experimental/imunologia , Diabetes Mellitus Tipo 1/imunologia , Diabetes Mellitus Tipo 1/metabolismo , Encefalomielite Autoimune Experimental/imunologia , N-Acetilglucosaminiltransferases/imunologia , Células Th1/imunologia , beta-Glucanas/imunologia , Animais , Antígenos CD/imunologia , Antígenos CD/metabolismo , Antígenos de Diferenciação/imunologia , Antígenos de Diferenciação/metabolismo , Autoimunidade/genética , Antígeno CTLA-4 , Diferenciação Celular/genética , Diferenciação Celular/imunologia , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Tipo 1/genética , Diabetes Mellitus Tipo 1/terapia , Encefalomielite Autoimune Experimental/genética , Encefalomielite Autoimune Experimental/metabolismo , Encefalomielite Autoimune Experimental/terapia , Endocitose/genética , Endocitose/imunologia , Complexo de Golgi/enzimologia , Complexo de Golgi/genética , Complexo de Golgi/imunologia , Humanos , Células Jurkat , Camundongos , Camundongos Knockout , N-Acetilglucosaminiltransferases/deficiência , N-Acetilglucosaminiltransferases/metabolismo , Receptores de Antígenos de Linfócitos T/imunologia , Receptores de Antígenos de Linfócitos T/metabolismo , Transdução de Sinais/imunologia , Células Th1/enzimologia , Uridina Difosfato N-Acetilglicosamina/genética , Uridina Difosfato N-Acetilglicosamina/imunologia , Uridina Difosfato N-Acetilglicosamina/metabolismo , beta-Glucanas/metabolismo
10.
J Invest Dermatol ; 127(5): 1205-9, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17218938

RESUMO

The widespread adoption of transdermal drug delivery has been limited by the barrier properties of the outermost layer of the epidermis, the stratum corneum (SC). A variety of approaches have been developed to overcome the barrier, including the use of a prodrug form of an active therapeutic agent to enhance transdermal delivery. Once in the epidermis, the pro-molecule is converted to the active drug by endogenous enzymes or simple chemical hydrolysis. The prodrug selected for the current studies, 1-ethyloxycarbonyl-5-fluorouracil, is known to enhance transdermal delivery of 5-fluorouracil, an important systemic antitumor drug. Using confocal Raman microscopy on pigskin biopsies treated with prodrug, we are able to image the spatial distribution of both prodrug and drug in the SC and viable epidermis, thereby providing information about permeation and metabolism. This approach may readily be extended to a variety of dermatological processes.


Assuntos
Fluoruracila/metabolismo , Microscopia Confocal/métodos , Pró-Fármacos/metabolismo , Pele/metabolismo , Análise Espectral Raman/métodos , Animais , Biotransformação , Epiderme/metabolismo , Permeabilidade , Pele/química , Suínos
11.
Eur Biophys J ; 36(4-5): 477-89, 2007 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-17051367

RESUMO

Surfactant protein C (SP-C) is known to be essential for lung function and the formation of a surface confined reservoir at the alveolar interface. The structural features relevant for the peptide's extraordinary ability to form extended three-dimensional structures were systematically investigated and are summarized in the present paper. The influence of palmitoylation was studied for full length SP-Cs as well as truncated variants with the N-terminal residues 1-17 and 1-13, respectively. The combined results from film balance measurements, fluorescence microscopy (FLM) and scanning force microscopy (SFM) reveal a fine-tuned balance between the influence of the palmitoyl chains and alpha-helical length. Native SP-C added to DPPC/DPPG monolayers (molar ratio 80:20) induced the formation of the surface confined reservoir independent of its palmitoylation degree. However, topographic images revealed that only bilayers and not multilayers where formed when the acyl chains were missing. The influence of palmitoylation increased when alpha-helical length was considerably reduced to 17 or even 13 amino acid residues. In these strongly truncated SP-C peptides palmitoyl chains increased monolayer stability and anchored the peptides in the lipid film. However, no multilayer formation was observed at all for all shortened peptides. The alpha-helix of SP-C seems to be a prerequisite for the formation of extended three-dimensional structures and obviously has to be able to span a lipid bilayer. Palmitoylation obviously mediates interactions between lipids and/or peptides not only within a protein/lipid film but also between neighbouring layers and induces a stacking of bilayers.


Assuntos
1,2-Dipalmitoilfosfatidilcolina/química , Bicamadas Lipídicas/química , Lipossomos/química , Pulmão/química , Fosfatidilgliceróis/química , Proteína C Associada a Surfactante Pulmonar/química , Proteína C Associada a Surfactante Pulmonar/ultraestrutura , Animais , Humanos , Conformação Proteica , Propriedades de Superfície
12.
Osteoporos Int ; 16(12): 2031-8, 2005 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16088360

RESUMO

Fourier-transform infrared microspectroscopy (FTIRM) allows analysis of mineral content, mineral crystal maturity and mineral composition at approximately 10-micron spatial resolution. Previous FTIRM analyses comparing 4-micron thick sections from non-decalcified iliac crest biopsies from women with post-menopausal osteoporosis, as contrasted with iliac crest tissue from individuals without evidence of metabolic bone disease, demonstrated significant differences in average mineral content (decreased in osteoporosis) and mineral crystal size/perfection (increased in osteoporosis). More importantly, these parameters, which vary throughout the tissue in relation to the tissue age in healthy bone, showed no such variation in bone biopsies from patients with osteoporosis. The present study compares the spatial and temporal variation in mineral quantity and properties in trabecular bone in high- and low-turnover osteoporosis. Specifically, six biopsies from women (n=5) and one man with high-turnover osteoporosis (age range 39-77) and four women and two men with low turnover osteoporosis (age range 37-63) were compared to ten "normal" biopsies from three men and seven woman (age range: 27-69). "High turnover" was defined as the presence of increased resorptive surface, higher than normal numbers of osteoclasts and greater than or equal to normal osteoblastic activity. "Low turnover" was defined as lower than normal resorptive surface, decreased osteoclast number and less than normal osteoblastic activity. Comparing variations in FTIR-derived values for each of the parameters measured at the surfaces of the trabecular bone to the maximum value observed in multiple trabeculae from each person, the high-turnover samples showed little change in the mineral: matrix ratio, carbonate: amide I ratio, crystallinity and acid phosphate content. The low-turnover samples also showed little change in these parameters, but in contrast to the high-turnover samples, the low-turnover samples showed a slight increase in these parameters, indicative of retarded, but existent resorption and formation. These data indicate that FTIR microspectroscopy can provide quantitative information on mineral changes in osteoporosis that are consistent with proposed mechanisms of bone loss.


Assuntos
Densidade Óssea/fisiologia , Ílio/química , Osteoporose/fisiopatologia , Adulto , Idoso , Amidas/análise , Biópsia/métodos , Reabsorção Óssea/fisiopatologia , Carbonatos/análise , Contagem de Células , Cristalização , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Osteoblastos/fisiologia , Osteoclastos , Fosfatos/análise , Espectroscopia de Infravermelho com Transformada de Fourier/métodos
13.
Eur Biophys J ; 34(3): 243-54, 2005 May.
Artigo em Inglês | MEDLINE | ID: mdl-15645307

RESUMO

A hydrophobic pulmonary surfactant protein, SP-C, has been implicated in surface-associated activities thought to facilitate the work of breathing. Model surfactant films composed of lipids and SP-C display a reversible transition from a monolayer to surface-associated multilayers upon compression and expansion at the air/water (A/W) interface. The molecular-level mechanics of this process are not yet fully understood. The current work uses atomic force microscopy on Langmuir-Blodgett films to verify the formation of multilayers in a dipalmitoylphosphatidylcholine, dipalmitoylphosphatidylglycerol, cholesterol, and SP-C model system. Isotherms of SP-C-containing films are consistent with exclusion and essentially complete respreading during compression and expansion, respectively. Multilayer formation was not detected in the absence of SP-C. Most notable are the results from IR reflection-absorption spectroscopy (IRRAS) conducted at the A/W interface, where the position and intensity of the Amide I band of SP-C reveal that the predominantly helical structure changes its orientation in monolayers versus multilayers. IRRAS measurements indicate that the helix tilt angle changed from approximately 80 degrees in monolayers to a transmembrane orientation in multilayers. The results constitute the first quantitative measure of helix orientation in mixed monolayer/multilamellar domains at the A/W interface and provide insight into the molecular mechanism for SP-C-facilitated respreading of surfactant.


Assuntos
Bicamadas Lipídicas/química , Fluidez de Membrana , Microscopia de Força Atômica/métodos , Modelos Biológicos , Modelos Químicos , Fosfolipídeos/química , Proteína C Associada a Surfactante Pulmonar/química , Surfactantes Pulmonares/química , Conformação Molecular , Conformação Proteica , Surfactantes Pulmonares/análise , Propriedades de Superfície
14.
J Am Chem Soc ; 127(1): 100-9, 2005 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-15631459

RESUMO

The Amide I contours of six globular proteins of varied secondary structure content along with a peptide model for collagen and pulmonary surfactant protein C have been simulated very closely by using a modified GF matrix method. The starting point for the method uses the three-dimensional structure as obtained from the Protein Data Bank. Elements of the interactions between peptide groups (e.g., transition dipole coupling) are very sensitive to tertiary structure, thus the current formalism demonstrates that the Amide I contour may be useful for a more detailed probe of 3-D conformation that goes beyond the traditional use of this band to probe the percentages of particular elements of secondary structure. For example, postulated changes to a known structure can be tested by comparing the new simulated band to the experimental band. A number of refinements to the transition dipole interaction calculation have been made. Most of the important interactions between the C=O oscillators that define the Amide I mode appear to have been identified, including through space transition dipole coupling, through valence bond and through hydrogen bond coupling. The eigenvector matrix produced by the method permits the contribution of each peptide group to the spectrum to be precisely determined. Analysis of the results shows that the often-used structure-frequency correlations are at best approximate and at worst misleading. The subbands from helices, sheets, turns, and loops are much broader and more overlapped than has been commonly assumed. Furthermore, the traditional alpha-helical marker band may be substantially distorted in short segments. Difference spectra based on isotope editing, a technique thought capable of revealing the spectral contributions of individual peptide groups, are shown to be prone to misinterpretation.


Assuntos
Amidas/química , Dobramento de Proteína , Proteínas/química , Animais , Proteínas de Transporte/química , Colágeno/química , Simulação por Computador , Proteínas de Ligação a Ácido Graxo , Cavalos , Ligação de Hidrogênio , Modelos Químicos , Mioglobina/química , Ressonância Magnética Nuclear Biomolecular , Estrutura Secundária de Proteína , Proteína C Associada a Surfactante Pulmonar/química , Ratos , Ribonuclease Pancreático/química , Espectroscopia de Infravermelho com Transformada de Fourier , Eletricidade Estática , Suínos
15.
J Bone Miner Res ; 19(12): 2000-4, 2004 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-15537443

RESUMO

UNLABELLED: Infrared imaging analysis of iliac crest biopsy specimens from patients with osteoporotic and multiple spontaneous fractures shows significant differences in the spatial variation of the nonreducible:reducible collagen cross-links at bone-forming trabecular surfaces compared with normal bone. INTRODUCTION: Although the role of BMC and bone mineral quality in determining fracture risk has been extensively studied, considerably less attention has been paid to the quality of collagen in fragile bone. MATERIALS AND METHODS: In this study, the technique of Fourier transform infrared imaging (FTIRI) was used to determine the ratio of nonreducible:reducible cross-links, in 2- to 4-microm-thick sections, from human iliac crest biopsy specimens (N = 27) at bone-forming trabecular surfaces. The biopsy specimens were obtained from patients that had been diagnosed as high- or low-turnover osteoporosis, as well as premenopausal women <40 years of age, with normal BMD and biochemistry, who suffered multiple spontaneous fractures. The obtained values were compared with previously published analyses of trabecular bone from normal non-osteoporotic subjects (N = 14, 6 males and 8 females; age range, 51-70 years). RESULTS AND CONCLUSIONS: Collagen cross-links distribution within the first 50 microm at forming trabecular surfaces in patients with fragile bone was markedly different compared with normal bone.


Assuntos
Osso e Ossos/patologia , Colágeno/química , Fraturas Ósseas/epidemiologia , Idoso , Biópsia , Densidade Óssea , Feminino , Humanos , Raios Infravermelhos , Masculino , Pessoa de Meia-Idade , Osteoporose/epidemiologia , Osteoporose Pós-Menopausa/epidemiologia , Espectroscopia de Infravermelho com Transformada de Fourier
16.
Appl Spectrosc ; 58(1): 1-9, 2004 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-14727714

RESUMO

Infrared spectroscopic imaging with 6-10 microm spatial resolution was used to characterize the changes in fracture callus mineral content, carbonate content, mineral crystallinity, and collagen maturity in femurs of 3-month-old ovariectomized rats treated with estrogen (estrogen sufficiency) or vehicle (estrogen deficiency). Comparisons were also made in these animals to cortical bone at a distance from the callus. Analyses at 4, 8, and 12 weeks post fracture demonstrated that healing was accelerated in the estrogen-sufficient animals as demonstrated by increasing mineral content and collagen maturity and decreasing carbonate incorporation.


Assuntos
Calcificação Fisiológica/efeitos dos fármacos , Estrogênios/administração & dosagem , Estrogênios/deficiência , Fraturas do Fêmur/patologia , Fraturas do Fêmur/fisiopatologia , Consolidação da Fratura/efeitos dos fármacos , Consolidação da Fratura/fisiologia , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Animais , Feminino , Fraturas do Fêmur/tratamento farmacológico , Ovariectomia , Ratos , Ratos Sprague-Dawley
17.
Langmuir ; 20(9): 3730-3, 2004 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-15875407

RESUMO

Infrared reflection-absorption spectroscopy (IRRAS) intensities of the Amide I vibration are used to develop a quantitative approach for determining the Euler angles that describe the orientation of protein beta-sheets in aqueous monolayer films. A synthetic amphipathic peptide, Val-Glu-Val-Orn-Val-Glu-Val-Orn-Val-Glu-Val-Orn-Val-OH is used as a test case. The pattern of Amide I frequencies suggests that the molecule is organized as an antiparallel beta-sheet at the air/water interface. The model used to simulate the Amide I intensities reveals that the beta-sheet has a slight preferential alignment parallel to the direction of compression; i.e., deviation from uniaxial symmetry is observed. In addition, the sheet is found to lie flat on the aqueous surface, with (presumably) the polar side chains interacting with the aqueous subphase. Limitations and advantages of the theoretical approach are discussed.


Assuntos
Peptídeos/química , Peptídeos/síntese química , Estrutura Secundária de Proteína , Análise Espectral
18.
Biochemistry ; 42(31): 9446-52, 2003 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-12899632

RESUMO

KLLLLKLLLLKLLLLKLLLLK (KL(4)) has been suggested to mimic some aspects of the pulmonary surfactant protein SP-B and has been tested clinically as a therapeutic agent for respiratory distress syndrome in premature infants [Cochrane, C. G., and Revak, S. D. (1991) Science 254, 566-568]. It is of obvious interest to understand the mechanism of KL(4) function as a guide for design of improved therapeutic agents. Attenuated total reflection (ATR) IR measurements have indicated that KL(4) is predominantly alpha-helical with a transmembrane orientation in lipid multilayers (1), a geometry quite different from the originally proposed peripheral membrane lipid interaction. However, the lipid multilayer model required for ATR may not be the best experimental paradigm to mimic the in vivo function of KL(4). In the current experiments, IR reflection-absorption spectroscopy (IRRAS) was used to evaluate peptide secondary structure in monolayers at the air/water interface, the physical state that best approximates the alveolar lining. In contrast to the ATR-IR results, KL(4) (2.5-5 mol %) films with either DPPC or DPPC/DPPG (7/3 mol ratio) adopted an antiparallel beta-sheet structure at all surface pressures studied > or =5 mN/m, including pressures physiologically relevant for lung function (40-72 mN/m). In contrast, in DPPG/KL(4) films, the dominant conformation was the alpha-helix over the entire pressure range, a possible consequence of enhanced electrostatic interactions. IRRAS has thus provided unique molecular structure information and insight into KL(4)/lipid interaction in a physiologically relevant state. A structural model is proposed for the response of the peptide to surface pressure changes.


Assuntos
Peptídeos/química , Surfactantes Pulmonares/química , Síndrome do Desconforto Respiratório do Recém-Nascido/tratamento farmacológico , 1,2-Dipalmitoilfosfatidilcolina/química , 1,2-Dipalmitoilfosfatidilcolina/metabolismo , Humanos , Recém-Nascido , Peptídeos e Proteínas de Sinalização Intercelular , Modelos Moleculares , Conformação Molecular , Fragmentos de Peptídeos/síntese química , Fragmentos de Peptídeos/química , Fragmentos de Peptídeos/metabolismo , Peptídeos/uso terapêutico , Fosfatidilgliceróis/química , Fosfatidilgliceróis/metabolismo , Estrutura Secundária de Proteína , Surfactantes Pulmonares/uso terapêutico , Espectrofotometria Infravermelho , Propriedades de Superfície
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