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PubMedDate not supplied

Overview of the diets of lower- and higher-income elderly and their food assistance options.

With the elderly becoming an ever-larger proportion of the American population, their dietary well-being is of increasing concern. In particular, lower-income elderly may face special challenges in maintaining a healthful diet. This group makes up a sizeable proportion of the elderly population; we estimate that almost 1 in 5 (19%) of the elderly have household incomes at or below 130% of the federal poverty level, the income level that generally qualifies a household to participate in the federal Food Stamp Program. Here we examine the dietary intakes and related behaviors, as well as the food security status, of lower- and higher-income elderly and review major US government food and nutrition assistance programs that can be of benefit to the elderly, particularly those of low income. Our subjects are individuals 60 years of age and over, living in community (noninstitutionalized) settings. Data on dietary intakes and behaviors were obtained from the US Department of Agriculture's Continuing Survey of Food Intakes by Individuals (CSFII), 1994-96. Food security data were obtained from the 1999 Current Population Survey (CPS), conducted by the US Census Bureau. For both the CSFII and the CPS, sampling weights were used to generate nationally representative estimates. We found that lower-income elderly consume significantly fewer calories than higher-income elderly, fewer servings of major Food Guide Pyramid food groups, and most nutrients. Approximately 6% of elderly households report some degree of food insecurity. Although food and nutrition assistance programs can benefit elderly individuals, many do not participate. Many lower-income elderly also face physiological and social obstacles to obtaining a healthful diet. How best to meet these varied needs is a challenge for nutrition educators, researchers, and policy makers.

Aged↗

PubMedDate not supplied

Maintaining food sufficiency: Coping strategies identified by limited-resource individuals versus nutrition educators.

OBJECTIVE: This study's purposes were to identify food acquisition and management coping strategies used by limited-resource individuals to maintain food sufficiency, compare strategies named by the target audience to those previously identified by nutrition educators, and examine these strategies to advance grounded theory. DESIGN: Eleven focus groups, conducted with 62 limited-resource individuals, elucidated coping strategies that they or others they knew used to acquire or manage food to maintain food sufficiency. The results were compared with practices as previously identified by nutrition educators who regularly worked with this audience. SUBJECTS/SETTINGS: Subjects aged 19 to 67 from throughout New Jersey were recruited by Food Stamp agencies, low-income outreach programs, soup kitchens, welfare offices, Head Start centers, shelters, and food pantries. RESULTS: Of the 95 coping strategies identified, 83% were known from nutrition educators previously. Ten new practices (eg, selling blood) had not previously been identified by educators. Four of 10 practices were not found in the literature (eg, repeated participation in research studies). Six practices previously reported by nutrition educators were not mentioned by the study population. IMPLICATIONS: Educators who work with limited-resource individuals are a good resource for research with this audience. Study findings may be important considerations for nutrition program planning and policy making.

Adaptation, Psychological↗

PubMedDate not supplied

New concepts for nutrition education in an era of welfare reform.

In response to welfare reform and the Food Stamp Nutrition Education Program's (FSNEP) goal of increasing clients' self-sufficiency, a literature review and small exploratory study were conducted to gain insight into a potential approach that would go beyond current nutrition education methods. Interviews with 17 FSNEP participants showed a widespread willingness to share food-related skills that others wanted to learn, some interest in cooperating on food-related projects, and frequent cases of social and geographic isolation. Based on these preliminary findings, we suggest the development and evaluation of nutrition education programs that appreciate and build on existing abilities of participants, provide opportunities for self-directed learning and activities, and build social support, social networks, and trust among participants while linking them to the broader community.

Food Services↗

PubMed2000

Childhood nutrition and poverty.

One in three children in Britain lives in poverty (households whose income was less than 50% average earnings). Low income is associated with poor nutrition at all stages of life, from lower rates of breast-feeding to higher intakes of saturated fatty acids and lower intakes of antioxidant nutrients. Moreover, there is increasing evidence that poor nutrition in childhood is associated with both short-term and long-term adverse consequences such as poorer immune status, higher caries rates and poorer cognitive function and learning ability. These problems arise primarily because parents do not have enough money to spend on food, not because money is being spent unwisely. Policy options to improve the dietary health of poor children include: giving more money to the parents by increasing Income Support (social security) payments, providing food stamps or vouchers, and using food budget standards to inform the levels of income needed to purchase an adequate diet; feeding children directly at school (not only at lunchtime but also at breakfast or homework clubs), by providing free fruit at school, and by increasing entitlement to free food amongst children living in households with low incomes; improving access to a healthy and affordable diet by first identifying 'food deserts' and then considering with retailers and local planners how best to provide food in an economical and sustainable way. The value of using food budget standards is illustrated with data relating expenditure on food to growth in children from 'at-risk' families (on low income, overcrowded, headed by a lone parent or with four or more children under 16 years of age) living in a poor area in London. Lower levels of expenditure are strongly associated with poorer growth and health, independent of factors such as birth weight, mother's height, or risk score. The present paper provides evidence that supports the need to review Government legislation in light of nutrition-related inequalities in the health of children.

Budgets↗

PubMed2001

Imaging of electroosmotic flow in plastic microchannels.

We have characterized electroosmotic flow in plastic microchannels using video imaging of caged fluorescent dye after it has been uncaged with a laser pulse. We studied flow in microchannels composed of a single material, poly(methyl methacrylate) (acrylic) or poly(dimethylsiloxane) (PDMS), as well as in hybrid microchannels composed of both materials. Plastic microchannels used in this study were fabricated by imprinting or molding using a micromachined silicon template as the stamping tool. We examined the dispersion of the uncaged dye in the plastic microchannels and compared it with results obtained in a fused-silica capillary. For PDMS microchannels, it was possible to achieve dispersion similar to that found in fused silica. For the acrylic and hybrid microchannels, we found increased dispersion due to the nonuniformity of surface charge density at the walls of the channels. In all cases, however, electroosmotic flow resulted in significantly less sample dispersion than pressure-driven flow at a similar velocity.

Journal Article↗

PubMed2003

Rapid prototyping of 2D structures with feature sizes larger than 8 microm.

This paper extends rapid prototyping for several types of lithography to the 8-25-microm size range, using transparency photomasks prepared by photoplotting. It discusses the technical improvement in photomask quality achieved by photoplotting, compared to the currently used image setting, and demonstrates differences in the resolution that can be obtained with photomasks with features in the 8-100-microm size range. These high-resolution photomasks were used to microfabricate microelectrodes, microlenses, and stamps for microcontact printing, following methods described previously.

Biological Assay↗

PubMed2004

Microcontact printing of DNA molecules.

The controlled placement of DNA molecules onto solid surfaces is the first step in the fabrication of DNA arrays. The sequential deposition of tiny drops containing the probe DNA fragments using arrays of spotting needles or ink jet nozzles has become a standard. However, a caveat of liquid spotting is the drying of the deposited drop because this creates the typical inhomogeneities, i.e., rims around the spot. Another drawback is that each DNA array is an original and has to be fabricated individually. Microcontact printing is a versatile technique to place proteins onto different target surfaces in uniformly patterned monolayers with high lateral resolution. Here, we show for the first time that DNA can also be printed with equally high resolution in the submicrometer range using an elastomeric stamp with chemically tailored surface. Two regimes for the transfer of the molecules were observed. Finally, microcontact printing of an array of DNA probes onto a solid support and its use in a subsequent hybridization assay was demonstrated.

Adsorption↗

PubMed2005

Microfiber-directed boundary flow in press-fit microdevices fabricated from self-adhesive hydrophobic surfaces.

We report a rapid microfluidic device construction technique which does not employ lithography or stamping methods. Device assembly physically combines a silicon wafer, an elastomer (poly(dimethylsiloxane) (PDMS)), and microfibers to form patterns of hydrophobic channels, wells, elbows, or orifices that direct fluid flow into controlled boundary layers. Tweezers are used to place glass microfibers in a defined pattern onto an elastomeric (PDMS) hydrophobic film. The film is then manually pressed onto a hydrophobic silicon wafer, causing it to adhere to the silicon wafer and form a liquid-tight seal around the fibers. Completed in 15 min, the technique results in an operable microdevice with micrometer-scale features of nanoliter volume. Microfiber-directed boundary flow is achieved by use of the surface wetting properties of the hydrophilic glass fiber and the hydrophobicity of surrounding surfaces. The simplicity of this technique allows quick prototyping of microfluidic components, as well as complete biosensor systems, such as we describe for the detection of pathogenic bacteria.

Air↗

PubMed2006

Chemiresistive vapor sensing with microscale films of gold monolayer protected clusters.

Here we report the stability, conductivity, and vapor-sensing properties of microcontact-printed films of 1.6-nm average diameter hexanethiolate-coated gold monolayer protected clusters (C6 Au MPCs). The C6 Au MPCs were stamped into parallel lines (approximately 1.2 microm wide and 400 nm thick) across two Au electrodes separated by a 1-microm gap. The chemiresistive vapor-sensing properties were measured for saturated toluene and 2-propanol vapors. As-prepared patterned Au MPC films were unstable in the presence of saturated toluene vapor, and their current response was irreversible. Chemically linking the films with vapor-phase hexanedithiol greatly improves their stability and leads to reversible responses. The extent of Au MPC cross-linking and vapor response to organic vapors varies with different exposure times to dithiol vapor. The response to toluene changed from 61 to 8% for exposures of 1 and 60 min, respectively, which is likely due to greater film flexibility with less dithiol exposure. The current measured through the films varies from 10(-11) to 10(-3) Angstroms as a function of the temperature between 250 and 320 degrees C, which correlates with the loss of organic material as measured by FT-IR spectroscopy and the change in thickness and width of the film as measured by atomic force microscopy. The vapor-sensing properties vary with temperature, current, and organic content in the film, which are all interrelated. Response to toluene decreased with increasing temperature and conductivity, while the response to 2-propanol was less predictable. Reducing the size of vapor-sensing devices based on Au MPCs is important for creating highly portable devices that can simultaneously detect multiple analytes. This work demonstrates a simple method for reducing the size of such devices down to the microscale and describes methods for maximizing response, stability, and reversibility.

Journal Article↗

PubMed2006

Microcontact printing-based fabrication of digital microfluidic devices.

Digital microfluidics is a fluid manipulation technique in which discrete droplets are actuated on patterned arrays of electrodes. Although there is great enthusiasm for the application of this technique to chemical and biological assays, development has been hindered by the requirement of clean room fabrication facilities. Here, we present a new fabrication scheme, relying on microcontact printing (microCP), an inexpensive technique that does not require clean room facilities. In microCP, an elastomeric poly(dimethylsiloxane) stamp is used to deposit patterns of self-assembled monolayers onto a substrate. We report three different microCP-based fabrication techniques: (1) selective etching of gold-on-glass substrates; (2) direct printing of a suspension of palladium colloids; and (3) indirect trapping of gold colloids from suspension. In method 1, etched gold electrodes are used for droplet actuation; in methods 2 and 3, colloid patterns are used to seed electroless deposition of copper. We demonstrate, for the first time, that digital microfluidic devices can be formed by microCP and are capable of the full range of digital microfluidics operations: dispensing, merging, motion, and splitting. Devices formed by the most robust of the new techniques were comparable in performance to devices formed by conventional methods, at a fraction of the fabrication time. These new techniques for digital microfluidics device fabrication have the potential to facilitate expansion of this technology to any research group, even those without access to conventional microfabrication tools and facilities.

Biocompatible Materials↗

PubMed2000

Room-temperature imprinting method for plastic microchannel fabrication

A new plastic imprinting method using a silicon template is demonstrated. This new approach obviates the necessity of heating the plastic substrate during the stamping process, thus improving the device yield from approximately 10 devices to above 100 devices per template. The dimensions of the imprinted microchannels were found to be very reproducible, with variations of less than 2%. The channel depths were dependent on the pressures applied and the materials used. Rather than bonding the open channels with another piece of plastic, a flexible and adhesive poly(dimethylsiloxane) film is used to seal the microchannels, which offers many advantages. As an application, isoelectric focusing of green fluorescence protein on these plastic microfluidic devices is illustrated.

Journal Article↗

PubMed2000

Prototyping of masks, masters, and stamps/molds for soft lithography using an office printer and photographic reduction

This paper describes a practical method for the fabrication of photomasks, masters, and stamps/molds used in soft lithography that minimizes the need for specialized equipment. In this method, CAD files are first printed onto paper using an office printer with resolution of 600 dots/in. Photographic reduction of these printed patterns transfers the images onto 35-mm film or microfiche. These photographic films can be used, after development, as photomasks in 1:1 contact photolithography. With the resulting photoresist masters, it is straightforward to fabricate poly(dimethylsiloxane) (PDMS) stamps/molds for soft lithography. This process can generate microstructures as small as 15 microm; the overall time to go from CAD file to PDMS stamp is 4-24 h. Although access to equipment-spin coater and ultraviolet exposure tool-normally found in the clean room is still required, the cost of the photomask itself is small, and the time required to go from concept to device is short. A comparison between this method and all other methods that generate film-type photomasks has been performed using test patterns of lines, squares, and circles. Three microstructures have also been fabricated to demonstrate the utility of this method in practical applications.

Journal Article↗

PubMed1995

Cross-linking of charybdotoxin to high-conductance calcium-activated potassium channels: identification of the covalently modified toxin residue.

High-conductance calcium-activated potassium (maxi-K) channels are composed of two subunits, alpha and beta. The pore-forming alpha subunit is a member of the mSlo family of K+ channels, whereas the beta subunit is a novel protein that modulates the biophysical and pharmacological properties of the channel complex. In the presence of a bifunctional cross-linking reagent, monoiodotyrosine charybdotoxin ([125I]ChTX) is covalently incorporated specifically into Lys69 of the beta subunit, which is located in a large extracellular loop of this protein. Using variants of ChTX which retain their channel-blocking activity and in which individual Lys residues have been mutated, we have identified the corresponding amino acid in ChTX that is involved in the cross-linking reaction. All of the ChTX mutants investigated bind to the maxi-K channel and display the same pharmacological profile as native ChTX in competition binding experiments. Whereas substitution of amino acids at positions 11 and 31 of ChTX yields wild-type cross-linking patterns, the peptide without a Lys at position 32 fails to incorporate into the beta subunit of the maxi-K channel. Given the model for the interaction between ChTX and the outer vestibule of the maxi-K channel that has been proposed (Stampe et al., 1994), our data constrain the maximum distance between the pore of this channel and the region in the extracellular loop of the beta subunit where the cross-linking reaction takes place to 11 A. This topological limit helps define structural features of the maxi-K channel that may aide in probing the functional interaction between alpha and beta subunits of the channel complex.

Animals↗

PubMedDate not supplied

Large area two-dimensional B cell arrays for sensing and cell-sorting applications.

Regular arrays of nonadherent B cells over large areas were produced with the use of micropatterned molecular templates consisting of a newly designed poly(allylamine)-g-poly(ethylene glycol) polycation graft copolymer. Polymer-on-polymer stamping (POPS) techniques were applied successfully to create micron scale patterns of the graft copolymer on negatively charged multilayer surfaces without losing resistance to the nonspecific adsorption of proteins. To generate templates for B cell arrays, the characteristics of the patterned surface were modified via introduction of surface biotinylation and specific protein adsorption. The qualities of B cell arrays resulting from each template suggest the binding strength between nonadherent B cells and the template surface is the controlling factor in the fabrication of clean and regular arrays of immobilized lymphocytes over large areas, which is critical in many bio-technological and immunological applications.

Adsorption↗

PubMedDate not supplied

Vascular smooth muscle cells on polyelectrolyte multilayers: hydrophobicity-directed adhesion and growth.

Polyelectrolyte multilayer films were employed to support attachment of cultured rat aortic smooth muscle A7r5 cells. Like smooth muscle cells in vivo, cultured A7r5 cells are capable of converting between a nonmotile "contractile" phenotype and a motile "synthetic" phenotype. Polyelectrolyte films were designed to examine the effect of surface charge and hydrophobicity on cell adhesion, morphology, and motility. The hydrophobic nature and surface charge of different polyelectrolyte films significantly affected A7r5 cell attachment and spreading. In general, hydrophobic polyelectrolyte film surfaces, regardless of formal charge, were found to be more cytophilic than hydrophilic surfaces. On the most hydrophobic surfaces, the A7r5 cells adhered, spread, and exhibited little indication of motility, whereas on the most hydrophilic surfaces, the cells adhered poorly if at all and when present on the surface displayed characteristics of being highly motile. The two surfaces that minimized cell adhesion consisted of two varieties of a diblock copolymer containing hydrophilic poly(ethylene oxide) and a copolymer bearing a zwitterionic group AEDAPS, (3-[2-(acrylamido)-ethyldimethyl ammonio] propane sulfonate). Increasing the proportion of AEDAPS in the copolymer decreased the adhesion of cells to the surface. Cells presented with micropatterns of cytophilic and cytophobic surfaces generated by polymer-on-polymer stamping displayed a surface-dependent cytoskeletal organization and a dramatic preference for adhesion to, and spreading on, the cytophilic surface, demonstrating the utility of polyelectrolyte films in manipulating smooth muscle cell adhesion and behavior.

Animals↗

PubMedDate not supplied

Enzymatic surface erosion of poly(trimethylene carbonate) films studied by atomic force microscopy.

In this article, the surface erosion of spin-coated poly(trimethylene carbonate) (PTMC) films by lipase solutions from Thermomyces lanuginosus was studied using atomic force microscopy (AFM). PTMC films (23-48 nm thick) were stable in water at 37 degrees C for 16 h, while after immersion in lipase solutions at 37 degrees C for 30 s and 1 min, the average thickness of the film decreased in time at a rate of 11.0 +/- 3.7 nm/min. The initially smooth films became significantly rougher during the erosion process. When the immersion time of the films in the lipase solutions was limited to less than 5 s, degradation of the surface was minimal and individual lipase molecules adsorbed on PTMC films could be discerned. By microcontact printing of the PTMC surfaces using a patterned PDMS stamp and lipase solution for 30 s, a predefined micropattern consisting of parallel, 5-microm-wide lines lying 5-nm deep and separated at a distance of 2 microm was formed. Friction images showed differences in surface properties between the recessed and protruding lines in the pattern.

Adhesiveness↗

PubMed2006

Patterned protein films on poly(lipid) bilayers by microcontact printing.

The use of polymerized lipid bilayers as substrates for microcontact printing (muCP) of protein films was investigated. We have previously shown that vesicle fusion of bis-SorbPC, a dienoate lipid, on glass and silica substrates, followed by redox-initiated radical polymerization, produces a planar supported lipid bilayer (PSLB) that is ultrastable(1a) [Ross, E. E.; Rozanski, L. J.; Spratt, T.; Liu, S.; O'Brien, D. F.; Saavedra, S. S. Langmuir 2003, 19, 1752] and highly resistant to nonspecific adsorption of dissolved proteins [Ross, E. E.; Spratt, T.; Liu, S.; Rozanski, L. J.; O'Brien, D. F.; Saavedra, S. S. Langmuir 2003, 19, 1766].(1b) Here we demonstrate that muCP of bovine serum albumin (BSA) onto a dried poly(bis-SorbPC) PSLB from a poly(dimethylsiloxane) (PDMS) stamp produces a layer of strongly adsorbed protein, comparable in surface coverage to films printed on glass surfaces. Immobilization of proteins on poly(PSLB)s has potential applications in biosensing, and this work shows that direct muCP of proteins is a technically simple approach to create immobilized monolayers, as well as multilayers of different proteins.

Biofilms↗

PubMed2006

Biochemical functionalization of polymeric cell substrata can alter mechanical compliance.

Biochemical functionalization of surfaces is an increasingly utilized mechanism to promote or inhibit adhesion of cells. To promote mammalian cell adhesion, one common functionalization approach is surface conjugation of adhesion peptide sequences such as Arg-Gly-Asp (RGD), a ligand of transmembrane integrin molecules. It is generally assumed that such functionalization does not alter the local mechanical properties of the functionalized surface, as is important to interpretations of macromolecular mechanotransduction in cells. Here, we examine this assumption systematically, through nanomechanical measurement of the nominal elastic modulus of polymer multilayer films of nanoscale thickness, functionalized with RGD through different processing routes. We find that the method of biochemical functionalization can significantly alter mechanical compliance of polymeric substrata such as weak polyelectrolyte multilayers (PEMs), increasingly utilized materials for such studies. In particular, immersed adsorption of intermediate functionalization reagents significantly decreases compliance of the PEMs considered herein, whereas polymer-on-polymer stamping of these same reagents does not alter compliance of weak PEMs. This finding points to the potential unintended alteration of mechanical properties via surface functionalization and also suggests functionalization methods by which chemical and mechanical properties of cell substrata can be controlled independently.

Animals↗