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1.
Bioengineering (Basel) ; 10(9)2023 Aug 24.
Artigo em Inglês | MEDLINE | ID: mdl-37760102

RESUMO

Although drying techniques are exciting alternatives to cryopreservation, it remains challenging to maintain tightly controlled temperatures and humidity levels during storage of dried products. The objective of this study was to determine if the addition of choline acetate to trehalose solution could enable a wider range of storage conditions for preservation of nuclei from fully grown oocytes, by allowing temporary humidity excursions (>44% relative humidity) that may lead to crystallization of trehalose and loss of DNA integrity. Using domestic cat germinal vesicle oocytes as a model, we characterized the recovery as well as the integrity of samples after microwave-assisted dehydration. Exposure to choline acetate alone did not impair the germinal vesicle's DNA integrity and only had a negative impact on the chromatin configuration. Choline acetate addition enabled us to reach lower moisture contents after 25 min of microwave-assisted drying. Sample recovery after rehydration was also better in the presence of choline acetate. The integrity of the germinal vesicle's DNA was not affected, while the chromatin configuration was impaired by the presence of choline acetate during dehydration. Importantly, choline acetate addition helped to maintain an amorphous state (absence of detrimental crystallization) during excursion from ideal humidity conditions.

2.
Cell Mol Bioeng ; 14(1): 101-112, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33643469

RESUMO

INTRODUCTION: Maintaining a stable dry state is critical for long-term preservation of live biomaterials at suprazero temperatures. The objective of the study was to characterize the effect of moisture content on DNA integrity within the germinal vesicle (GV) of feline oocytes following dehydration and storage at 22-24 °C. METHODS: Using microwave-assisted drying, conditions that led to a predictable and stable moisture content in trehalose solutions were determined. To explore moisture content stability during storage, trehalose samples were dried for 15 min and stored in glass vials at 11 or 43% RH for 8 weeks. To examine whether this condition allowed proper storage of GVs, permeabilized cat oocytes were incubated in trehalose for 10 min and dried for 15 or 30 min. Oocytes then were rehydrated to assess DNA integrity either directly after drying or after 8 weeks of storage in an 11% RH environment. Raman spectroscopy was used to identify the states of dried samples during storage. RESULTS: Moisture content was stable during the storage period. There was no significant difference in DNA integrity between fresh and dried samples without storage. After 8 weeks of storage, DNA integrity was maintained in GVs dried for 30 min. Samples dried for 15 min and stored were compromised, suggesting crystallization of the preservation matrix during storage. Biostabilization was optimal when samples were directly processed to moisture contents consistent with storage in the glassy state. CONCLUSION: Microwave-assisted drying processing and storage conditions were optimized to ensure stable long-term storage of structural and functional properties of genetic resources.

3.
Methods Mol Biol ; 2180: 203-220, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-32797413

RESUMO

Dry preservation has become an attractive approach for the long-term storage of biologics. By removing water from the matrix to solidify the sample, refrigeration needs are reduced, and thus storage costs are minimized and shipping logistics greatly simplified. This chapter describes two energy deposition technologies, namely, microwave and laser systems, that have recently been used to enhance the rate and nature of solution densification for the purpose of anhydrous preservation of feline oocytes, sperm, and egg white lysozyme in trehalose glass. Several physical screening methodologies used to determine the suitability of an amorphous matrix for biopreservation are also introduced in this chapter.


Assuntos
Produtos Biológicos/química , Criopreservação/veterinária , Crioprotetores/metabolismo , Liofilização/métodos , Lasers , Micro-Ondas , Preservação Biológica/métodos , Animais , Gatos , Galinhas , Criopreservação/métodos , Dessecação , Feminino , Vidro/química , Masculino , Muramidase/química , Oócitos/citologia , Espermatozoides/citologia
4.
Biomed Opt Express ; 11(2): 801-816, 2020 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-32133224

RESUMO

Protein-based drugs have been developed to treat a variety of conditions and assays use immobilized capture proteins for disease detection. Freeze-drying is currently the standard for the preservation of proteins, but this method is expensive and requires lengthy processing times. Anhydrous preservation in a trehalose amorphous solid matrix offers a promising alternative to freeze-drying. Light assisted drying (LAD) is a processing method to create an amorphous trehalose matrix. Proteins suspended in a trehalose solution are dehydrated using near-infrared laser light. The laser radiation accelerates drying and as water is removed the trehalose forms a protective matrix. In this work, LAD samples are characterized to determine the crystallization kinetics of the trehalose after LAD processing and the distribution of amorphous trehalose in the samples. These characteristics influence the long-term stability of the samples. Polarized light imaging revealed that LAD processed samples are stable against crystallization during low-humidity storage at room temperature. Scanning white light interferometry and Raman spectroscopy indicated that trehalose was present across samples in an amorphous form. In addition, differential scanning microcalorimetry was used to measure the thermodynamic characteristics of the protein lysozyme after LAD processing. These results demonstrate that LAD does not change the properties of this protein.

5.
Transplantation ; 104(5): e125-e134, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32000259

RESUMO

BACKGROUND: Maintaining functional vessels during preservation of vascularized composite allografts (VCAs) remains a major challenge. The University of Wisconsin (UW) solution has demonstrated significant short-term benefits (4-6 h). Here we determined whether the new hypothermic resuscitation and preservation solution HypoRP improves both structure, survival, and function of pig arteries during storage for up to 6 days. METHODS: Using porcine swine mesenteric arteries, the effects of up to 6-day incubation in a saline (PBS), UW, or HypoRP solution on the structure, cell viability, metabolism, and function were determined. RESULTS: After incubation at 4°C, for up to 6 days, the structures of the arteries were significantly disrupted, especially the tunica media, following incubation in PBS, in contrast with incubation in the HypoRP solution and to a lesser extent, in UW solution. Those disruptions were associated with increased active caspase 3 indicative of apoptosis. Additionally, while incubation in PBS led to a significant decrease in the metabolic activity, UW and HypoRP solutions allowed a stable to increased metabolic activity following 6 days of cold storage. Functional responsiveness to phenylephrine (PE) and sodium nitroprusside (SNP) decreased over time for artery rings stored in PBS and UW solution but not for those stored in HypoRP solution. Moreover, artery rings cold-stored in HypoRP solution were more sensitive to ATP. CONCLUSIONS: The HypoRP solution improved long-term cold storage of porcine arteries by limiting structural alterations, including the collagen matrix, reducing apoptosis, and maintaining artery contraction-relaxation functions for up to 6 days.


Assuntos
Artérias Mesentéricas/efeitos dos fármacos , Soluções para Preservação de Órgãos/farmacologia , Preservação de Órgãos/métodos , Vasoconstrição/fisiologia , Adenosina/farmacologia , Alopurinol/farmacologia , Animais , Sobrevivência Celular , Endotélio Vascular/citologia , Endotélio Vascular/fisiologia , Seguimentos , Glutationa/farmacologia , Insulina/farmacologia , Artérias Mesentéricas/citologia , Artérias Mesentéricas/fisiologia , Modelos Animais , Rafinose/farmacologia , Suínos
6.
Phys Chem Chem Phys ; 20(32): 20899-20909, 2018 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-30067254

RESUMO

Spatial and temporal characteristics of molecular structure in ternary solutions of trehalose and choline dihydrogen phosphate (CDHP) are studied using molecular dynamics simulations at 300 K for a range of solute concentrations with a 2 : 1 stoichiometric ratio of trehalose to CDHP. For a given molecular configuration, water molecules are classified as interior (only neighboring other water molecules) or interfacial (at least one solute neighbor). As a tagged water molecule diffuses, it dynamically exchanges between interior and interfacial type as its local environment changes, with differences in hydrogen-bond strength between different molecular species creating a persistent preference for interfacial water. At high solute concentrations, interfacial and interior water have similar diffusivity, which allows for water to collectively act as a plasticizer. The percolation threshold for water, defined as the maximum solute concentration at which there still exists a water cluster that spans the simulation box, was found to be slightly under the liquid-glass transition, estimated to be near 84.5% solute concentration based on the onset of a volume hysteresis effect, which was not previously studied in the computational literature. The systems were observed to be highly inhomogeneous, with interlaced percolating networks of water and solute coexisting at intermediate concentrations. The density of interior water was found to decrease with increasing solute concentration, creating low-density regions within the matrix.


Assuntos
Fosforilcolina/química , Trealose/química , Água/química , Ligação de Hidrogênio , Simulação de Dinâmica Molecular , Estrutura Molecular , Transição de Fase , Soluções , Propriedades de Superfície
7.
J Biomed Opt ; 23(7): 1-8, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-30022643

RESUMO

A light-based processing method to create an amorphous trehalose matrix for the stabilization of proteins is discussed. This method has potential applications in the stabilization of protein-based therapeutics and diagnostics. During light-assisted drying (LAD), proteins suspended in a trehalose solution are dehydrated using near-infrared (NIR) laser light. The goal of this study was to determine processing parameters that resulted in fast processing times and low end moisture contents (EMC), while maintaining the functionality of embedded proteins. We compared the effect of changing processing wavelength, power and resulting sample temperature, and substrate material on the EMC for two NIR laser sources (1064 and 1850 nm). The 1850-nm laser resulted in the lowest EMC (0.03 ± 0.01 gH2O / gDryWeight) after 20 min of processing on glass microfiber paper. This suggests a storage temperature of 68.3°C. We also tested the functionality of a model protein, lysozyme, after LAD processing using a standard assay. LAD showed no significant effect on the functionality of lysozyme when processed at a maximum temperature of ∼44 ° C to an EMC of 0.17 ± 0.06 gH2O / gDryWeight. LAD is a promising technique for forming amorphous trehalose solids that could stabilize proteins at ambient temperatures.


Assuntos
Dessecação/métodos , Estabilidade Proteica/efeitos da radiação , Proteínas Recombinantes , Temperatura Alta , Raios Infravermelhos , Proteínas Recombinantes/química , Proteínas Recombinantes/efeitos da radiação , Trealose/química
8.
Curr Stem Cell Rep ; 3(1): 45-53, 2017 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-28966905

RESUMO

PURPOSE OF THE REVIEW: Over the past several decades, cryopreservation has been widely used to preserve cells during long term storage, but advances in stem cell therapies, regenerative medicine, and miniaturized cell-based diagnostics and sensors are providing new targets of opportunity for advancing preservation methodologies. The advent of microfluidics-based devices is an interesting case in which the technology has been used to improve preservation processing, but as the devices have evolved to also include cells, tissues, and simulated organs as part of the architecture, the biochip itself is a desirable target for preservation. In this review, we will focus on the synergistic co-development of preservation methods and biochip technologies, while identifying where the challenges and opportunities lie in developing methods to place on-chip biologics on the shelf, ready for use. RECENT FINDINGS: Emerging studies are demonstrating that the cost of some biochips have been reduced to the extent that they will have high utility in point-of-care settings, especially in low resource environments where diagnostic capabilities are limited. Ice-free low temperature vitrification and anhydrous vitrification technologies will likely emerge as the preferred strategy for long-term preservation of bio-chips. SUMMARY: The development of preservation methodologies for partially or fully assembled biochips would enable the widespread distribution of these technologies and enhance their application.

9.
Theriogenology ; 103: 36-43, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28772113

RESUMO

Characterizing the resilience of mammalian cells to non-physiological conditions is necessary to develop preservation and long-term storage strategies at low or ambient temperatures. Using the domestic cat model, the objective of the study was to characterize structural integrity (morphology and DNA damage) as well as functional properties (sperm aster formation and embryo formation after sperm injection) of spermatozoa after microwave-assisted drying to a moisture content compatible with storage in a glassy state at supra-zero temperatures. In Experiment 1, cat epididymal spermatozoa were porated with hemolysin and dried (using a commercial microwave oven set to 20% power) in the presence of trehalose for up to 50 min in a low humidity environment (11%) before measuring moisture content and sample temperature. In Experiment 2, morphology and DNA integrity were evaluated in sperm dried for up to 30 min (using the same method as above) versus fresh spermatozoa. In Experiment 3, the functionality of sperm dried for 30 min versus fresh sperm cells was evaluated after injection into oocytes based on sperm aster formation (5 h post-injection) and embryo development in vitro over 7 days. Moisture contents compatible with dry state storage were reached after 30 min of microwave-assisted drying. After rehydration, sperm morphology was not affected and the percentages of cells with damaged DNA (∼6.5%) was similar to the fresh controls. Sperm aster diameters appeared to be generally smaller for dried-rehydrated cells compared to the fresh controls. This observation was consistent with a lower proportion of blastocyst formation after injection with dried spermatozoa (6.5%) compared to fresh spermatozoa (15%). However, the blastocyst quality based on the total blastomere number was not affected by the sperm treatment. This is the first and encouraging report in any species so far demonstrating that spermatozoa can be dried using microwaves without causing irreversible damage to the cellular structure and function.


Assuntos
Gatos , Preservação do Sêmen/veterinária , Animais , Fragmentação do DNA , Dessecação , Desenvolvimento Embrionário , Masculino , Micro-Ondas , Oócitos/crescimento & desenvolvimento , Preservação do Sêmen/métodos , Injeções de Esperma Intracitoplásmicas/veterinária , Espermatozoides/fisiologia , Fatores de Tempo , Água
10.
Nat Biotechnol ; 35(6): 530-542, 2017 06 07.
Artigo em Inglês | MEDLINE | ID: mdl-28591112

RESUMO

The ability to replace organs and tissues on demand could save or improve millions of lives each year globally and create public health benefits on par with curing cancer. Unmet needs for organ and tissue preservation place enormous logistical limitations on transplantation, regenerative medicine, drug discovery, and a variety of rapidly advancing areas spanning biomedicine. A growing coalition of researchers, clinicians, advocacy organizations, academic institutions, and other stakeholders has assembled to address the unmet need for preservation advances, outlining remaining challenges and identifying areas of underinvestment and untapped opportunities. Meanwhile, recent discoveries provide proofs of principle for breakthroughs in a family of research areas surrounding biopreservation. These developments indicate that a new paradigm, integrating multiple existing preservation approaches and new technologies that have flourished in the past 10 years, could transform preservation research. Capitalizing on these opportunities will require engagement across many research areas and stakeholder groups. A coordinated effort is needed to expedite preservation advances that can transform several areas of medicine and medical science.


Assuntos
Criopreservação/tendências , Técnicas de Cultura de Órgãos/tendências , Preservação de Órgãos/tendências , Transplante de Órgãos/tendências , Medicina Regenerativa/tendências , Previsões , Humanos , Preservação de Tecido/tendências
11.
Cryobiology ; 76: 74-91, 2017 06.
Artigo em Inglês | MEDLINE | ID: mdl-28428046

RESUMO

Cryopreservation has become a central technology in many areas of clinical medicine, biotechnology, and species conservation within both plant and animal biology. Cryoprotective agents (CPAs) invariably play key roles in allowing cells to be processed for storage at deep cryogenic temperatures and to be recovered with high levels of appropriate functionality. As such, these CPA solutes possess a wide range of metabolic and biophysical effects that are both necessary for their modes of action, and potentially complicating for cell biological function. Early successes with cryopreservation were achieved by empirical methodology for choosing and applying CPAs. In recent decades, it has been possible to assemble objective information about CPA modes of action and to optimize their application to living systems, but there still remain significant gaps in our understanding. This review sets out the current status on the biological and chemical knowledge surrounding CPAs, and the conflicting effects of protection versus toxicity resulting from the use of these solutes, which are often required in molar concentrations, far exceeding levels found in normal metabolism. The biophysical properties of CPAs that allow them to facilitate different approaches to cryogenic storage, including vitrification, are highlighted. The topics are discussed with reference to the historical background of applying CPAs, and the relevance of cryoprotective solutes in natural freeze tolerant organisms. Improved cryopreservation success will be an essential step in many future areas such as regenerative medicine, seed banking, or stem cell technology. To achieve this, we will need to further improve our understanding of cryobiology, where better and safer CPAs will be key requirements.


Assuntos
Criopreservação , Crioprotetores/farmacologia , Vitrificação , Animais , Proteínas Anticongelantes , Fenômenos Fisiológicos Celulares , Congelamento , Humanos , Gelo , Preservação de Órgãos , Soluções
12.
Biopreserv Biobank ; 15(2): 158-168, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28398834

RESUMO

The current gold standard for sperm preservation is storage at cryogenic temperatures. Dry preservation is an attractive alternative, eliminating the need for ultralow temperatures, reducing storage maintenance costs, and providing logistical flexibility for shipping. Many seeds and anhydrobiotic organisms are able to survive extended periods in a dry state through the accumulation of intracellular sugars and other osmolytes and are capable of returning to normal physiology postrehydration. Using techniques inspired by nature's adaptations, attempts have been made to dehydrate and dry preserve spermatozoa from a variety of species. Most of the anhydrous preservation research performed to date has focused on mouse spermatozoa, with only a small number of studies in nonrodent mammalian species. There is a significant difference between sperm function in rodent and nonrodent mammalian species with respect to centrosomal inheritance. Studies focused on reproductive technologies have demonstrated that in nonrodent species, the centrosome must be preserved to maintain sperm function as the spermatozoon centrosome contributes the dominant nucleating seed, consisting of the proximal centriole surrounded by pericentriolar components, onto which the oocyte's centrosomal material is assembled. Preservation techniques used for mouse sperm may therefore not necessarily be applicable to nonrodent spermatozoa. The range of technologies used to dehydrate sperm and the effect of processing and storage conditions on fertilization and embryogenesis using dried sperm are reviewed in the context of reproductive physiology and cellular morphology in different species.


Assuntos
Dessecação , Preservação do Sêmen , Espermatozoides/fisiologia , Animais , Dano ao DNA , Fertilização , Humanos , Masculino , Especificidade da Espécie
13.
Sci Rep ; 6: 28795, 2016 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-27387435

RESUMO

Dry preservation of biologics in sugar glasses is regarded as a promising alternative to conventional cryopreservation. Evidence from various studies has suggested that there is a critical range of water content beyond which the viability of preserved biologics can be greatly compromised. In this study the viability of T-cells was determined as a function of end water content after microwave-assisted drying in trehalose solutions. Hydrogen-bonding and clustering phenomena in trehalose solutions of the same moisture content were also evaluated using molecular dynamics simulation. Post-rehydration viability decreased dramatically within the range of 0.1-1 gH2O/gdw. Molecular modeling revealed that as the water content approached 0.1 gH2O/gdw the matrix formed a large interconnected trehalose skeleton with a minimal number of bound water molecules scattered in the bulk. The diffusion coefficients of trehalose oxygen atoms most distant from the glycosidic linkage fluctuated around 7.5 × 10(-14) m(2)/s within the range of 0.02-0.1 gH2O/gdw and increased again to ~1.13 × 10(-13) m(2)/s at 0.01 gH2O/gdw and below due to the loss of water in the free volume between trehalose molecules. These insights can guide the optimal selection of final moisture contents to advance dry preservation methods.


Assuntos
Preservação Biológica/métodos , Trealose/química , Água/química , Algoritmos , Sobrevivência Celular , Análise Custo-Benefício , Dessecação , Difusão , Humanos , Ligação de Hidrogênio , Células Jurkat , Micro-Ondas , Simulação de Dinâmica Molecular , Açúcares , Linfócitos T/citologia , Temperatura
14.
Biopreserv Biobank ; 13(3): 164-71, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26035005

RESUMO

The ability to compact and inject the cat germinal vesicle (GV) into a recipient cytoplast allows exploration of a new fertility preservation strategy that avoids whole oocyte freezing. The objective of the present study was to understand the impact of water loss and storage time on GV DNA integrity. Immature cat oocytes were exposed to 1.5 M trehalose for 10 min before microwave-assisted dehydration for 0, 5, 10, 15, 20, 25, 30, or 40 min. Oocytes then were rehydrated to assess chromatin configuration and the incidence of DNA fragmentation (TUNEL assay). The moisture content progressively decreased (p<0.05) from 1.7 to 0.1 gH2O/gDW over the first 30 min, but did not decrease further (p>0.05) after 40 min. Chromatin configuration was unaffected (p>0.05) over time. The percentage of GVs with DNA fragmentation was unaltered (p>0.05) from 0 to 30 min of treatment (range, 6.1%-12%), but increased (p<0.05) to 32.5% after 40 min. Next, the influence of storage at two different supra-zero temperatures after 30 min of drying was investigated. Oocyte-loaded, microwave-treated filters were individually sealed in Dri-Shield moisture barrier bags and stored at 4°C or ambient temperature for 0 to 8 weeks. Moisture contents gradually decreased (p<0.05) from 0.12 to 0.10 gH2O/gDW after 8 weeks of storage at 4°C or ambient temperature. The percentage of GVs with DNA fragmentation more than doubled (p<0.05) from 0 (14.3%) to 2 days (30.0%-33.0%), but remained stable (p>0.05) thereafter (1 through 4 weeks, 25.0%-35.0%). Collective results demonstrate the feasibility of using microwave processing to dehydrate the mammalian GV to a moisture content that is nonlethal and enables nonfrozen storage, an alternative approach for preserving the maternal genome at cool or ambient temperature.


Assuntos
Dessecação/métodos , Micro-Ondas , Modelos Animais , Oócitos/citologia , Animais , Gatos , Cromatina/metabolismo , Fragmentação do DNA , Feminino , Umidade , Cinética , Temperatura , Fatores de Tempo , Água/química
15.
J Phys Chem B ; 119(22): 6820-7, 2015 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-25955786

RESUMO

Approximately a decade ago it was observed that adding a small amount (5 wt %) of glycerol to trehalose could substantially improve the stability of enzymes stored in these glasses even though the final glass transition temperature (Tg) was reduced by ∼20 K. This finding inspired great interest in the fast dynamics of dehydrated trehalose/glycerol mixtures, leading to the observation that suppression of fast dynamics was optimal in the presence of ∼5 wt % of glycerol. It was also recognized that the fast dynamics should, in theory, be related to the fragility of these glass formers, but experimental confirmation of this hypothesis has been lacking for trehalose/glycerol mixtures or any other mixtures of this nature. In the present study a dynamic mechanical analyzer (DMA) was used to determine both the Tg and the kinetic fragility index (m) of trehalose/glycerol mixtures within the mass fraction range of 80-100 wt % of trehalose. It was found that the fragility index correlated with the mass fraction of trehalose in a nonmonotonic manner, with a local minimum between 87.5 and 95 wt % of trehalose, whereas the composition dependence of Tg was found to follow a Gordon-Taylor-like relationship, with no local minimum. The composition of 5-12.5 wt % glycerol in trehalose thus yielded a matrix that maximized the strong glass-forming contribution of glycerol, while minimizing its Tg lowering effect. This quantitative evidence supports speculation about the fragility characteristics of these mixtures that has been ongoing for the past decade. The DMA-based Tg and fragility determination method developed in this study represents a new approach for identifying optimal compositions for preservation of biologics.


Assuntos
Glicerol/química , Trealose/química , Estabilidade de Medicamentos , Cinética , Fenômenos Mecânicos , Temperatura de Transição
16.
Pharm Res ; 32(7): 2217-28, 2015 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-25537342

RESUMO

PURPOSE: The present study is aimed at understanding how the interactions between sugar molecules and phosphate ions affect the glass transition temperature of their mixtures, and the implications for pharmaceutical formulations. METHODS: The glass transition temperature (Tg) and the α-relaxation temperature (Tα) of dehydrated trehalose/sodium phosphate mixtures (monobasic or dibasic) were determined by differential scanning calorimetry and dynamic mechanical analysis, respectively. Molecular dynamics simulations were also conducted to investigate the microscopic interactions between sugar molecules and phosphate ions. The hydrogen-bonding characteristics and the self-aggregation features of these mixtures were quantified and compared. RESULTS: Thermal analysis measurements demonstrated that the addition of NaH2PO4 decreased both the glass transition temperature and the α-relaxation temperature of the dehydrated trehalose/NaH2PO4 mixture compared to trehalose alone while both Tg and Tα were increased by adding Na2HPO4 to pure trehalose. The hydrogen-bonding interactions between trehalose and HPO4(2-) were found to be stronger than both the trehalose-trehalose hydrogen bonds and those formed between trehalose and H2PO4(-). The HPO4(2-) ions also aggregated into smaller clusters than H2PO4(-) ions. CONCLUSIONS: The trehalose/Na2HPO4 mixture yielded a higher T g than pure trehalose because marginally self-aggregated HPO4(2-) ions established a strengthened hydrogen-bonding network with trehalose molecules. In contrast H2PO4(-) ions served only as plasticizers, resulting in a lower Tg of the mixtures than trehalose alone, creating large-sized ionic pockets, weakening interactions, and disrupting the original hydrogen-bonding network amongst trehalose molecules.


Assuntos
Vidro/química , Fosfatos/química , Trealose/química , Vitrificação , Soluções Tampão , Ligação de Hidrogênio , Concentração de Íons de Hidrogênio , Simulação de Dinâmica Molecular , Temperatura de Transição
17.
J Cancer Educ ; 30(2): 294-300, 2015 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-25249181

RESUMO

This study explored federally qualified health center (FQHC) patients' perceptions about colorectal cancer screening (CRCS) tests, including immunochemical fecal occult blood tests (iFOBT), as well as preferences for receiving in-clinic education about CRCS. Eight mixed gender focus groups were conducted with 53 patients. Findings centered on three thematic factors: (1) motivators and impediments to CRCS, (2) test-specific preferences and receptivity to iFOBTs, and (3) preferences for entertaining and engaging plain language materials. Results informed the development of educational priming materials to increase CRCS using iFOBT in FQHCs.


Assuntos
Colonoscopia/estatística & dados numéricos , Neoplasias Colorretais/diagnóstico , Neoplasias Colorretais/psicologia , Centros Comunitários de Saúde/estatística & dados numéricos , Detecção Precoce de Câncer/psicologia , Conhecimentos, Atitudes e Prática em Saúde , Educação de Pacientes como Assunto , Idoso , Neoplasias Colorretais/prevenção & controle , Governo Federal , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Sangue Oculto , Cooperação do Paciente , Padrões de Prática Médica , Inquéritos e Questionários , Estados Unidos
18.
Colloids Surf B Biointerfaces ; 123: 575-81, 2014 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-25444662

RESUMO

Choline carboxylates, ChCm, with m=2-10 and choline oleate are known as biocompatible substances, yet their influence on biological membranes is not well-known, and the effect on human skin has not previously been investigated. The short chain choline carboxylates ChCm with m=2, 4, 6 act as hydrotropes, solubilizing hydrophobic compounds in aqueous solution, while the longer chain choline carboxylates ChCm with m=8, 10 and oleate are able to form micelles. In the present study, the cytotoxicity of choline carboxylates was tested using HeLa and SK-MEL-28 cells. The influence of these substances on liposomes prepared from dipalmitoylphosphatidylcholine (DPPC) was also evaluated to provide insights on membrane interactions. It was observed that the choline carboxylates with a chain length of m>8 distinctly influence the bilayer, while the shorter ones had minimal interaction with the liposomes.


Assuntos
Membrana Celular/efeitos dos fármacos , Colina/química , Líquidos Iônicos/química , Calorimetria , Linhagem Celular , Células HeLa , Humanos , Micelas
19.
J Phys Chem B ; 118(49): 14546-54, 2014 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-25405831

RESUMO

Protectants which are cell membrane permeable, such as glycerol, have been used effectively in the cryopreservation field for a number of decades, for both slow cooling and vitrification applications. In the latter case, the glass transition temperature (Tg) of the vitrification composition is key to its application, dictating the ultimate storage conditions. It has been observed that the addition of some electrolytes to glycerol, such as MgCl2, could elevate the Tg of the mixture, thus potentially providing more storage condition flexibility. The microscopic mechanisms that give rise to the Tg-enhancing behavior of these electrolytes are not yet well understood. The current study focuses on molecular dynamics simulation of glycerol mixed with a variety of metal chlorides (i.e., NaCl, KCl, MgCl2, and CaCl2), covering a temperature range that spans both the liquid and glassy states. The characteristics of the ion-dipole interactions between metal cations and hydroxyl groups of glycerol were analyzed. The interruption of the original hydrogen-bonding network among glycerol molecules by the addition of ions was also investigated in the context of hydrogen-bonding quantity and lifetime. Divalent metal cations were found to significantly increase the Tg by strengthening the interacting network in the electrolyte/glycerol mixture via strong cation-dipole attractions. In contrast, monovalent cations increased the Tg insignificantly, as the cation-dipole attraction was only slightly stronger than the original hydrogen-bonding network among glycerol molecules. The precursor of crystallization of NaCl and KCl was also observed in these compositions, potentially contributing to weak Tg-enhancing ability. The Tg-enhancing mechanisms elucidated in this study suggest a structure-enhancing role for divalent ions that could be of benefit in the design of protective formulations for biopreservation purposes.


Assuntos
Cloretos/química , Crioprotetores/química , Eletrólitos/química , Glicerol/química , Polimerização , Ligação de Hidrogênio , Metais/química , Simulação de Dinâmica Molecular
20.
Mater Sci Eng C Mater Biol Appl ; 44: 422-9, 2014 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-25280724

RESUMO

Recently there has been considerable interest in developing sugar glasses that enable storage of biologics without refrigeration. Microfiber filter papers are good substrates for drying biologics in the presence of sugar glass-formers, providing for an even distribution of samples and an enhanced surface area for drying, but the opaqueness prevents macroscopic observation of the sample and can introduce complexities that impede physical characterization. Because drying kinetics and processing conditions can impact the relaxation dynamics (e.g., α- and ß-relaxation), which can influence the efficacy of the glass as a stabilizer, methods are needed that can enable a determination of relaxation phenomena of sugar glasses in such complex environments. In this study we present a method which provides verification of the absence of crystallinity following drying on glass fiber filter paper and also enables the determination of relaxation characteristics of amorphous sugar compositions embedded within these filter substrates. Using material pockets to contain the sugar glass-embedded microfiber paper, the α-relaxation temperature, Tα, was determined as a function of the water content in trehalose and sucrose samples using Dynamic Mechanical Analysis (DMA). Results were verified by comparison with previous calorimetric and spectroscopic studies. The data also demonstrated the plasticizing effects of water, as Tα was shown to correlate with water content via a Gordon-Taylor-like relationship. Our findings validate a new approach for determining the relaxation characteristics of microfiber embedded sugar glasses, and offer new insights into the relaxation characteristics of glasses prepared by microwave-assisted drying on filter papers.


Assuntos
Vidro/química , Sacarose/química , Trealose/química , Dessecação , Sorbitol/química , Temperatura , Água/química
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