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PubMed2005

Micropatterned polymer substrates control alignment of proliferating Schwann cells to direct neuronal regeneration.

Microcontact printed polymeric substrates were evaluated for their ability to control Schwann cell attachment and direct proliferation, as Schwann cell guidance is a crucial factor in directing peripheral nerve regeneration. Elastomeric stamps of poly(dimethylsiloxane) were "inked" with laminin, a permissive protein for Schwann cell adhesion, and stamped onto poly(methyl methacrylate) substrates to create patterns of lines and intervals varying from 10 to 50 microm wide. Schwann cells were seeded onto the substrates in serum-free media. After 4h, media was replaced with serum-containing growth media and changed daily thereafter. The addition of growth media to stimulate proliferation initially caused some loss in cell orientation relative to the laminin pattern, but when monolayer formation was complete, a high degree of cell orientation was observed. As both cell-cell contacts and surface coverage were maximized, the Schwann cells achieved an even higher order of orientation than observed during the early stages of proliferation. Significantly, smaller pattern widths increased the degree of orientation, regardless of interval width. Our results indicate that patterned polymeric substrates may enhance peripheral nerve regeneration by creating a highly ordered Schwann cell matrix for guidance of neurons.

Adsorption↗

PubMed2006

Micromolding of shape-controlled, harvestable cell-laden hydrogels.

Encapsulation of mammalian cells within hydrogels has great utility for a variety of applications ranging from tissue engineering to cell-based assays. In this work, we present a technique to encapsulate live cells in three-dimensional (3D) microscale hydrogels (microgels) of controlled shapes and sizes in the form of harvestable free standing units. Cells were suspended in methacrylated hyaluronic acid (MeHA) or poly(ethylene glycol) diacrylate (PEGDA) hydrogel precursor solution containing photoinitiator, micromolded using a hydrophilic poly(dimethylsiloxane) (PDMS) stamp, and crosslinked using ultraviolet (UV) radiation. By controlling the features on the PDMS stamp, the size and shape of the molded hydrogels were controlled. Cells within microgels were well distributed and remained viable. These shape-specific microgels could be easily retrieved, cultured and potentially assembled to generate structures with controlled spatial distribution of multiple cell types. Further development of this technique may lead to applications in 3D co-cultures for tissue/organ regeneration and cell-based assays in which it is important to mimic the architectural intricacies of physiological cell-cell interactions.

Animals↗

PubMed2006

The microcontact imprinting of proteins: the effect of cross-linking monomers for lysozyme, ribonuclease A and myoglobin.

The performance of molecularly imprinted polymers (MIPs) is of interest to researchers in the field of analytical chemistry, and in the pharmaceutical and food industries. Because the choice of the functional monomer(s) plays a key role in the selectivity of a MIP, the synthesis of an effective, tight-binding MIP can be difficult and time-consuming, involving the evaluation of the binding performance of MIPs of many different compositions. In this study, we report an express method combining molecular imprinting and microcontact printing techniques to prepare a polymer thin film as an artificial antibody. In addition to the microcontact printing technique, isothermal titration of monomers to proteins stamps was investigated to screen the functional monomer for MIPs. Finally, the importance of the choice of cross-linking monomers in MIPs was studied, and these studies suggest that monomers containing an optimal length PEG spacer give higher imprinting effectiveness. Several model antigens (lysozyme, ribonuclease A and myoglobin) were adsorbed on a cover glasses that were pretreated with hexamethyldisilazane (HMDS). These protein stamps were then contacted with different monomer solutions (cross-linking monomers) on a glass slide substrate. Photopolymerization yielded the molecularly imprinted polymer. This technique, analogous to microcontact printing, allows for the rapid, parallel synthesis of MIPs of different compositions, and requires very small volumes of monomers (ca. 4 microL). The technique also avoids potential solubility problems with the molecular targets. Of several cross-linking monomers screened, tetraethyleneglycol dimethacrylate (TEGDMA) gave the most selective lysozyme binding, while polyethyleneglycol 400 dimethacrylate (PEG400DMA) were most selective for ribonuclease A and myoglobin.

Adsorption↗

PubMed2006

Restoration of engraved marks on steel surfaces by etching technique.

It is known that restoration of erased engraved identification marks on the engine and the chassis of a car or on a firearm has low success rate. Unlike stamping, engraving on a metal surface leaves no pronounced, permanent subsurface deformation in the crystalline structure, also called dislocation that can be revealed by suitable methods. Hence, the current research work investigated whether metallographic reagents used in the restoration of stamp (compression) marks could be applied to recover engraved marks on steel surfaces and also to establish the sensitivity and effectiveness of some of these reagents for the restoration of the marks. Experiments were conducted by mechanically engraving alphanumeric characters on several steel plates using a computer controlled engraving machine called Gravograph. The markings were later erased from the above steel plates by removing the metal in stages of 0.01 mm through 0.04 mm below the bottom of the engraving. Several plates were thus prepared wherein each one had been abraded to a specific depth. Then eight metallographic reagents were tested on each one of the above erased plates using a swabbing technique. The results had shown that while most of the reagents were able to restore marks up to certain levels of erasure, the reagent 5 g copper sulphate, 60 ml water, 30 ml concentrated ammonium hydroxide and 60 ml concentrated hydrochloric acid restored marks erased to a depth of 0.04 mm below the engraving depth, thus presenting itself the most sensitive reagent. Quite significantly, the above reagent was also able to decipher successfully the original engraved marks that had been erased and engraved with a new number, or obliterated by centre punching. The results of this research work should benefit the forensic practitioners engaged in the serial number recovery on vehicles, firearms and other objects.

Journal Article↗

PubMed2005

Electronic signatures for long-lasting storage purposes in electronic archives.

Communication and co-operation in healthcare and welfare require a certain set of trusted third party (TTP) services describing both status and relation of communicating principals as well as their corresponding keys and attributes. Additional TTP services are needed to provide trustworthy information about dynamic issues of communication and co-operation such as time and location of processes, workflow relations, and system behaviour. Legal and ethical requirements demand securely stored patient information and well-defined access rights. Among others, electronic signatures based on asymmetric cryptography are important means for securing the integrity of a message or file as well as for accountability purposes including non-repudiation of both origin and receipt. Electronic signatures along with certified time stamps or time signatures are especially important for electronic archives in general, electronic health records (EHR) in particular, and especially for typical purposes of long-lasting storage. Apart from technical storage problems (e.g. lifetime of the storage devices, interoperability of retrieval and presentation software), this paper identifies mechanisms of e.g. re-signing and re-stamping of data items, files, messages, sets of archived items or documents, archive structures, and even whole archives.

Computer Security↗

PubMed2006

Impact of organizational structure on nurses' job satisfaction: a questionnaire survey.

BACKGROUND: Nurses' job satisfaction is an important issue because of its impact on the quality of the nursing job. Therefore, it receives a lot of attention in the international nursing literature but insight into the sources of nurses' job satisfaction is yet insufficient, in particular for sources related to organizational structure. OBJECTIVES: We contribute by investigating the relationship between the organizational structure variables, formalization, centralization and specialization, and nurses' job satisfaction. This allows us to learn whether structural changes can help to improve satisfaction, and therefore nurses' work quality. DESIGN: Data were collected by questionnaires in a random sample of 764 non-managing nurses in three Belgian general care hospitals. We measured satisfaction by Stamps and Piedmont's work satisfaction index. Structure was also measured by an existing scale. RESULTS: The results support the negative effect of centralization and the clearly positive effects of specialization and formalization on nurses' job satisfaction. These effects differ according to the different dimensions of satisfaction. Furthermore, pay is the most important dimension of nurses job satisfaction but the dimension least influenced by organizational structure. CONCLUSIONS: The importance of the dimension pay in nurses' job satisfaction, which is not a function of organizational structure, is limiting hospitals in improving nurses' job satisfaction. However, organizational structure is related to the other dimensions of satisfaction. Especially, the fact that specialization and formalization are, contrary to our hypotheses, only positively related to satisfaction is important from a practice perspective and for further research. Furthermore, our data indicates that there is a need to refine one of the dimensions of Stamps and Piedmont index.

Adult↗

PubMed2005

A "contract for change" increases produce consumption in low-income women: a pilot study.

This study determined whether a "Contract for Change" goal-setting exercise enhanced the effectiveness of the Expanded Food and Nutrition Education/Food Stamp Nutrition Education programs to increase produce consumption in low-income (<130% of poverty) women after 4 weeks. Thirty-eight participants were randomized in this three-group parallel arm study: (a) control group participants received life-skills lessons, (b) the education group received the Expanded Food and Nutrition Education/Food Stamp Nutrition Education "Food Guide Pyramid" lessons, and (c) the contract group also received the "Food Guide Pyramid" series and completed a "Contract for Change." It was hypothesized that the contract group would have the greatest increases in advancement toward dietary change and produce consumption. Compared with controls, the contract group significantly moved toward acceptance of vegetable consumption (P < or = .05). Compared with the education group, the contract group significantly increased fruit consumption. Results suggest that nutrition professionals can effectively use goal-setting to assist low-income populations with dietary change.

Adult↗

PubMed2006

Enclosing a pen with a postal questionnaire can significantly increase the response rate.

BACKGROUND AND OBJECTIVES: It is important to maximize response rates to postal questionnaires. We compared the impact of three low-cost interventions on response rates. METHODS: A 2 x 2 x 2 factorial trial was conducted, nested within TOMBOLA (Trial Of Management of Borderline and Other Low-grade Abnormal smears). Three interventions were evaluated: (1) enclosing a TOMBOLA-branded pen with the questionnaire (as opposed to no pen); (2) sending the questionnaires by first class post (as opposed to second class); and (3) enclosing a preaddressed return envelope on which there was a second class postage stamp (rather than a freepost business-reply envelope). Nine hundred thirty women, aged 20-59 years, due to receive a TOMBOLA psychosocial questionnaire by post during June-August 2003 were randomized. RESULTS: Enclosing a pen resulted in a statistically significant 7.0% increase in the cumulative proportion of questionnaires returned (from 61.5 to 68.5%; P = .002). The adjusted odds of response was significantly raised (odds ratio [OR] = 1.38, 95% confidence interval [CI] 1.04-1.82). Neither first class post nor providing a stamped envelope had a significant impact on response. There were no interactions between the interventions. CONCLUSIONS: Enclosing a pen with a questionnaire can significantly increase response. This low-cost strategy was effective against a background of "good practice" with regard to the administration of postal questionnaires.

Adult↗

PubMed2006

The effect of different propolis harvest methods on its lead contents determined by ET AAS and UV-visS.

Argentinean propolis is exported to different countries, specially Japan. The market demands propolis quality control according to international standards. The analytical determination of some metals, as lead in food, is very important for their high toxicity even in low concentrations and because of their harmful effects on health. Flavonoids, the main bioactive compounds of propolis, tend to chelate metals as lead, which becomes one of the main polluting agents of propolis. The lead found in propolis may come from the atmosphere or it may be incorporated in the harvest, extraction and processing methods. The aim of this work is to evaluate lead level on Argentinean propolis determined by electrothermal atomic absorption spectrometry (ET AAS) and UV-vis spectrophotometry (UV-visS) methods, as well as the effect of harvest methods on those contents. A randomized test with three different treatments of collection was made to evaluate the effect of harvest methods. These procedures were: separating wedges (traditional), netting plastic meshes and stamping out plastic meshes. By means of the analysis of variance technique for multiple comparisons (ANOVA) it was possible to conclude that there are significant differences between scraped and mesh methods (stamped out and mosquito netting meshes). The results obtained in the present test would allow us to conclude that mesh methods are more advisable than scraped ones in order to obtain innocuous and safe propolis with minor lead contents. A statistical comparison of lead determination by both, ET AAS and UV-visS methods, demonstrated that there is not a significant difference in the results achieved with the two analytical techniques employed.

Electrochemistry↗

PubMedDate not supplied

The impact of homeless shelters on food access and choice among homeless families in Minnesota.

OBJECTIVE: To determine how and where homeless families access food, and to determine factors that influence food choice. DESIGN: Seven focus groups (90 minutes each) were conducted by two moderators and audio-taped. SETTING: Two homeless shelters serving families. PARTICIPANTS: Fifty-three parents or guardians (M = 11; F = 42) with children 3-12 years of age. Most participants had completed high school or higher education. PHENOMENON OF INTEREST: Food choice and food access among homeless families. ANALYSIS: Transcripts evaluated for consistency, coded, and evaluated for dominant themes. RESULTS: Limited cooking and storage space, and poor meal timing and food options at the shelters resulted in participants developing strategies to alleviate hunger. Strategies used to obtain food included using food stamps, stealing food, eating food in grocery stores, pawning personal items, using savvy shopping habits, scavenging in dumpsters (obtaining items such as food from dumpsters), and sacrificing food for children. CONCLUSIONS AND IMPLICATIONS: Homeless families find strategies to prevent food insecurity. Food stamp usage is a common strategy, but it often is insufficient to meet monthly needs, indicating the need for reevaluation of program components. The shelter environment's impact on families' food choices suggests a role for nutritionists in ensuring availability of adequate, nutritious foods. Future research is needed to evaluate the impact of the shelter environment on homeless families' overall nutritional status.

Adult↗

PubMed2004

A fast flexible ink-jet printing method for patterning dissociated neurons in culture.

We present a new technique that uses a custom-built ink-jet printer to fabricate precise micropatterns of cell adhesion materials for neural cell culture. Other work in neural cell patterning has employed photolithography or "soft lithographic" techniques such as micro-stamping, but such approaches are limited by their use of an un-alterable master pattern such as a mask or stamp master and can be resource-intensive. In contrast, ink-jet printing, used in low-cost desktop printers, patterns material by depositing microscopic droplets under robotic control in a programmable and inexpensive manner. We report the use of ink-jet printing to fabricate neuron-adhesive patterns such as islands and other shapes using poly(ethylene) glycol as the cell-repulsive material and a collagen/poly-D-lysine (PDL) mixture as the cell-adhesive material. We show that dissociated rat hippocampal neurons and glia grown at low densities on such patterns retain strong pattern adherence for over 25 days. The patterned neurons are comparable to control, un-patterned cells in electrophysiological properties and in immunocytochemical measurements of synaptic density and inhibitory cell distributions. We suggest that an inexpensive desktop printer may be an accessible tool for making micro-island cultures and other basic patterns. We also suggest that ink-jet printing may be extended to a range of developmental neuroscience studies, given its ability to more easily layer materials, build substrate-bound gradients, construct out-of-plane structure, and deposit sources of diffusible factors.

Animals↗

PubMed2004

A simple soft lithographic route to fabrication of poly(ethylene glycol) microstructures for protein and cell patterning.

We present a simple, direct soft lithographic method to fabricate poly(ethylene glycol) (PEG) microstructures for protein and cell patterning. This lithographic method involves a molding process in which a uniform PEG film is molded with a patterned polydimethylsiloxane stamp by means of capillary force. The patterned surfaces created by this method provide excellent resistance towards non-specific protein and cell adsorption. The patterned substrates consist of two regions: the molded PEG surface that acts as a resistant layer and the exposed substrate surface that promotes protein or cell adsorption. A notable finding here is that the substrate surface can be directly exposed during the molding process due to the ability to control the wetting properties of the polymer on the stamp, which is a key factor to patterning proteins and cells.

Adsorption↗

PubMedDate not supplied

Y2K: effects on pacemaker and implantable defibrillator programmers.

All permanent pacemakers and implantable defibrillators (PPM/ICDs) will continue to function as programmed without regard to the date in the year 2000 (Y2K). All manufacturers contacted reassured us that some of these devices incorporate a day/year clock in the circuitry; however, these are not involved in sensing or delivering programmed therapy. Some manufacturers' device programmers will roll over to the year 2000 without any problems at all, whereas others may have difficulty with date and time stamping on printed reports. We tested 14 different types of PPM/ICD programmers for Y2K compliance using 8 tests. Five of the 14 models passed each test and were labeled at our institution with a green "Y2K" sticker to identify them as Y2K compatible and needing no special attention after December 31, 1999. The most common test failed was the ability to roll the date forward from December 31, 1999, with the programmer power off. Organizations should consider testing and replacing noncompliant device programmers or placing a red sticker with "Y2K" crossed out on noncompliant pieces. The red sticker alerts the advanced practice nurse or physician to the need to confirm the appropriate date and time in the programmer after startup in the year 2000 and before interrogating or programming any PPM/ICD, to avoid inappropriate date and time stamping on printed reports from that programmer.

Attitude of Health Personnel↗

PubMed2000

Ordered networks of rat hippocampal neurons attached to silicon oxide surfaces.

The control of neuronal cell position and outgrowth is of fundamental interest in the development of applications ranging from cellular biosensors to tissue engineering. We have produced rectangular networks of functional rat hippocampal neurons on silicon oxide surfaces. Attachment and network formation of neurons was guided by a geometrical grid pattern of the adhesion peptide PA22-2 which matches in sequence a part of the A-chain of laminin. PA22-2 was applied by contact printing onto the functionalised silicon oxide surface and was immobilised by hetero-bifunctional cross-linking with sulfo-GMBS. Geometric pattern matching was achieved by microcontact printing using a polydimethylsiloxane (PDMS) stamp. In this way the produced grid pattern ranged from 3 to 20 microm in line width and from 50 to 100 microm in line distances. As shown by atomic force microscopy (AFM), line widths and line distances of the peptide pattern differ less than 0.5 microm from the used PDMS stamp. The height of the layer of immobilised PA22-2 was approximately 3.5 nm implying the layer to be monomolecular. Immobilised PA22-2 was capable of binding anti-PA22-2 antibodies indicating that the function of the peptide was not compromised by immobilisation. Rat hippocampal neurons, cultured at low density in serum-free medium, were applied to the growth matrix of PA22-2-coated substrates and, within 1-3 h of culture, formed a network-like pattern that more or less matched the printed grid. Reliability and reproducibility of neuronal network formation depended on the geometry, line width and node diameter of the grid pattern. The immobilised neurons showed resting membrane potentials comparable with controls and, already after 1 day of culture, were capable of eliciting action potentials. The suitability of the immobilised neurons for the study of man-made neural networks and for multi-site recordings from a functional neuronal network is discussed.

Animals↗

PubMed1996

Limited field irradiation in early stage (T1-2N0) non-small cell lung cancer.

BACKGROUND AND PURPOSE: Radiotherapy can effectively control non-small cell lung cancers (NSCLC) of limited size. This study is conducted to investigate whether limited field irradiation, without irradiation of regional lymph nodes, can safely be used in these patients. MATERIALS AND METHODS: Between 1988 and 1993, 31 patients with operable T1-2N0 NSCLC received radiotherapy (48 Gy in 12 fractions) to a limited ('postage stamp') field. The hilum and mediastinum were not included in the radiation portals. RESULTS: Overall survival was 42% at 3 years. Disease-specific survival at 3 years was 76%. One patient developed an isolated regional failure, one had a combined local and distant failure, one had a combined local, regional and distant failure, while three patients failed at distant sites only. Thus, only two patients (6%) recurred regionally. CONCLUSIONS: This study shows that 'postage stamp' irradiation is an effective alternative to surgery. Radiation of the hilar and mediastinal lymph nodes can be omitted in these pulmonary compromised patients.

Aged↗

PubMed2000

A software tool to acquire, synchronise and playback multimedia data: an application in kinesiology.

Assessing the physical condition of the human body frequently requires evaluating different tests performed by different devices. This information has to be analysed simultaneously to derive conclusions, and so a temporal relationship must be established between the data sources. In this paper, synchronisation of the sources of information is achieved by synchronising the clocks of computers connected in a Local Area Network. A clock synchronisation protocol is used and a global time is stamped in each information data flow. During analysis, the time-stamp is used to playback the data in a synchronised way. The proposed system is valid for any medical application in which data synchronisation is needed. However, it has initially been used in a distributed medical environment for analysing electrical muscular activity and lumbar movement. The dual aim is to detect injuries and plan training sessions for athletes. It was specifically used to analyse data generated by: electromyographs; lumbar equipment; and images generated by video cameras. The simple operation of the application and the precision of the synchronisation protocol enabled several interesting medical conclusions to be made.

Electromyography↗

PubMed1990

Skin grafts.

Skin grafting is a method to reconstruct the skin covering on areas of the body where there are defects and insufficient surrounding skin for advancement or for creation of flaps. Grafts are classified according to their host-donor relationship and by their thickness. Autogenous grafts, taken from one area of the body and applied to another area, are the type of graft used most often clinically. Pieces of skin are taken from one area of the body, prepared and applied over a defect that has also been properly prepared to accept the graft. The defect to which a graft is applied must be a healthy bed of granulation tissue or tissue that is vascular enough to produce a bed of granulation tissue. In its new location, the graft will develop a new blood supply and attachment to underlying tissues. This is accomplished as the graft undergoes the processes of fibrinous adherence, plasmatic imbibition, inoculation, and new vessel ingrowth. The types of grafts described in this chapter are split-thickness, full-thickness, seed, strip, and stamp grafts. Each of these graft types must be prepared using certain techniques, and each one has its inherent advantages and disadvantages. Split-thickness grafts may require considerable skill and/or expensive equipment to perform. Although they "take" better than full-thickness grafts, they are usually less cosmetically attractive. Full-thickness grafts require no special skill or expensive equipment, and their cosmetic appearance is better than that of split-thickness grafts, but they do not take as well as split-thickness grafts. Seed and strip grafts are easily accomplished and require no special instruments; however, their cosmetic appearance is not good. Stamp grafts have some of the properties associated with split-thickness grafts as well as those of seed and strip grafts, since they combine features of both.

Animals↗

PubMedDate not supplied

Evaluation of the fracture site mechanical properties in vivo by monitoring the motion of a dynamic pin clamp during simulated walking.

OBJECTIVE: To monitor pin clamp motion using a displacement sensor over time during weight bearing and to investigate whether this method could contribute to quantitative assessment of the mechanical properties of fracture healing. METHODS: Patients with a shaft fracture of the tibia were monitored, all of whom were in the stage of dynamization. The hifixator equipped with a ball bearing mechanism was used as a dynamic external fixator. The displacement was recorded versus time during stamping with weight bearing of the patients. The displacement curve had an oscillatory component synchronized with touch down and lift up of the foot, a time-dependent component expressed by shifting of the baseline, and an irreversible component during a non-weight bearing period after stamping. The three components were analyzed with a simple Voigt model. RESULTS: In all patients, both the amplitude of the oscillatory component and the time-dependent component expressed as retardation time decreased as fracture healing proceeded, and by the time of fixator removal the irreversible component had disappeared. CONCLUSIONS: The monitoring method could quantitatively evaluate viscoelastoplasticity of the healing fracture site. RELEVANCE: Until now, there has been few method for assessing the viscoelastic property of the healing fracture site in vivo. Although the method described here involves some assumptions and approximations, it was able to quantitatively assess the viscoelasticity of the healing fracture site.

Adult↗