Reusable Devices Research Articles

CFD investigations of steam penetration, air-removal and condensation inside hollow loads and cavities

Steam sterilization is the most commonly used method to sterilize re-usable medical devices. All non-condensable gases (NCGs) must be removed from every hollow space within the medical device in order to guarantee the high heat transfer rates that result from wall condensation. In this work, a computational fluid dynamics (CFD) model was developed to simulate the fluid flow, temperature, heat transfer, and steam penetration inside the steam sterilizer with a particular emphasis on hollow loads (cavities). The flow inside the steam sterilizer was modeled with a three-phase Eulerian-Eulerian model, which includes evaporation and condensation effects.A very numerically inexpensive model was developed and implemented into the CFD code in order to calculate the heat transfer that occurs due to wall condensation in the presence of NCGs. The CFD model was validated by the measurements of temperature, pressure, and NCGs content after different cycle times. The average error between the measured pressures and temperatures and the results of the simulations were 0.16% and 0.54%, respectively. Furthermore, the steam penetration at the ends of the hollow loads was measured using chemical indicators. The simulation results show that a steam concentration of approximately 5% is sufficient to change the color of the chemical indicators. The CFD model developed is able to predict the volume fraction of NCGs, as well as steam penetration inside the steam sterilizer, including the hollow loads (cavities). Thus, it should be easier for future developers of steam sterilizers to investigate steam penetration within hollow loads and cavities.

The presence of fecal test soil protects bacteria during cleaning/disinfection.

Reusable medical devices (RMDs) must be reprocessed between uses to render them safe for each use and each patient. Cleaning used devices removes organic and inorganic soil making them either safe for reuse or ready for disinfection/sterilization depending on the device. Although cleaning is an important step in a RMD's life cycle, it is not always a priority during device design. In addition, when performing cleaning validation, it is recommended that the manufacturer takes into consideration, what the most appropriate or worst case conditions are in terms of type of soil or the presence of bacteria. This study compared the ability of three different cleaning/disinfecting agents (water, alcohol, and bleach) to remove bacteria and fecal test soil from two different polymers: polypropylene and ultrahigh molecular weight polyethylene (UHMWPE) with two different roughness. There were some differences in the effects of the cleaning/disinfecting agents, the materials, and the roughness depending on the particular circumstances. However, the most consistent effect on the removal of bacteria was the presence of soil, which protected the bacteria from being removed. Conversely, the presence of bacteria played little role in the removal of soil. Although the interactions between material type and roughness, soil type, and bacteria are complicated, they should be taken into account during device design and reprocessing validation to create a device that is easy and safe to use. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1706-1710, 2019.

Assessing the Reusability of 3D-Printed Photopolymer Microfluidic Chips for Urine Processing.

Three-dimensional (3D) printing is emerging as a method for microfluidic device fabrication boasting facile and low-cost fabrication, as compared to conventional fabrication approaches, such as photolithography, for poly(dimethylsiloxane) (PDMS) counterparts. Additionally, there is an increasing trend in the development and implementation of miniaturized and automatized devices for health monitoring. While nonspecific protein adsorption by PDMS has been studied as a limitation for reusability, the protein adsorption characteristics of 3D-printed materials have not been well-studied or characterized. With these rationales in mind, we study the reusability of 3D-printed microfluidics chips. Herein, a 3D-printed cleaning chip, consisting of inlets for the sample, cleaning solution, and air, and a universal outlet, is presented to assess the reusability of a 3D-printed microfluidic device. Bovine serum albumin (BSA) was used a representative urinary protein and phosphate-buffered solution (PBS) was chosen as the cleaning agent. Using the 3-(4-carboxybenzoyl)quinoline-2-carboxaldehyde (CBQCA) fluorescence detection method, the protein cross-contamination between samples and the protein uptake of the cleaning chip were assessed, demonstrating a feasible 3D-printed chip design and cleaning procedure to enable reusable microfluidic devices. The performance of the 3D-printed cleaning chip for real urine sample handling was then validated using a commercial dipstick assay.

Reusable Core Needle Biopsy Device for Low-Resource Settings

Purpose The core needle biopsy (CNB) procedure is an essential part of breast cancer diagnosis. Current CNB devices on the market are not suitable for low-resource settings, which makes early breast cancer diagnosis inaccessible for women in these areas. Disposable CNB devices are the gold standard of breast cancer diagnostic tools in high-income countries, but the single-use cost—approximately $40 to $200—is unaffordable in low- and middle-income countries. Existing reusable devices are susceptible to internal contamination as blood travels back through the coaxial needle into the driver and thus requires laborious cleaning procedures. Methods After conducting more than 100 interviews with stakeholders at 18 hospitals in the United States, South Africa, and Peru, we devised criteria for the device. The device must prevent internal driver contamination and match the standard tissue sample size. We report the design and development of a reusable CNB device with disposable needles that trap contamination. To demonstrate where blood travels in current reusable devices and prove that internal contamination can be completely eliminated, we created an external attachment that interfaces with the Bard Magnum, an existing reusable driver that yields internal contamination. To prove our concept, we evaluated contamination rates by placing water-indicating tape inside the Bard driver and firing the device into a plastic test tube that was filled with blood-mimicking solutions and covered with a latex glove. Results When we fired the existing Bard Magnum device without our attachment, contaminants entered the internal compartment of the device both times, as shown by the water-indicating tape; however, when the device was fired with our external needle attachment, the water-indicating tape was completely clean, which verified that there was no internal contamination. Conclusion We can conclude from our contamination testing that blood enters the device as a result of contaminants traveling back between the faces of the needle and sheath into the device’s driver and that our external attachment eliminates this risk. Using these insights, we are currently developing a full reusable driver device with novel disposable needles that trap contamination to remove safety concerns associated with reusable devices, lower procedural cost, and increase access to breast cancer diagnostic tools in low-resource settings. AUTHORS' DISCLOSURES OF POTENTIAL CONFLICTS OF INTEREST The following represents disclosure information provided by authors of this manuscript. All relationships are considered compensated. Relationships are self-held unless noted. I = Immediate Family Member, Inst = My Institution. Relationships may not relate to the subject matter of this manuscript. For more information about ASCO's conflict of interest policy, please refer to www.asco.org/rwc or ascopubs.org/jco/site/ifc . Megan Callanan Employment: Stryker Spine Patents, Royalties, Other Intellectual Property: Ithemba LLC Laura Hinson Patents, Royalties, Other Intellectual Property: Ithemba LLC Madeline Lee Patents, Royalties, Other Intellectual Property: Ithemba LLC Sophia Triantis Patents, Royalties, Other Intellectual Property: Ithemba LLC Amir Manbachi Research Funding: Siemens Healthineers (Inst) Susan Harvey Honoraria: Hologic Inc, IBM Watson Imaging Consulting or Advisory Role: IBM Watson, Hologic Inc Research Funding: IBM Watson

Failure Mechanisms of Polymeric Medical Devices

Medical devices manufactured today typically require a number of different components and materials. Commonly, mass-produced devices utilize biocompatible polymers for their external surfaces. In this article, we discuss common failure mechanisms of polymers and a number of contributing factors, related to both the use and manufacturing of these devices. Reprocessing and cleaning of reusable medical devices can also contribute to their failures when incompatible substances or techniques are used. Thorough postmarket reporting of any medical device failure can allow enhancements of the device to be made and will ultimately improve patient safety.

PMD181 - PATIENT PREFERENCE FOR CHRONIC OBSTRUCTIVE PULMONARY DISEASE (COPD) TREATMENT INHALERS: A DISCRETE CHOICE EXPERIMENT (DCE) IN FRANCE

Patients’ preference is increasingly explored for COPD treatments, notably because poor inhaler adherence is a major challenge. Understanding inhaler preferences may contribute to adherence and improve long-term outcomes. This study aimed to identify and quantify preferences for convenience-related inhaler attributes in French moderate-to-severe COPD patients, with DCE methodology. No previous studies report on these characteristics in this population. Attributes were defined from a literature search, expert- and patient interviews. An online DCE with COPD patients aged 40-75, using an inhaler for COPD was conducted, including a 2-phase pilot study and cognitive-debriefing interviews. The choice scenarios presented fictitious inhalers with 7 attributes; shape, dose insertion, dose preparation, dose release, dose confirmation, dose counter, and reusability. The COPD Assessment Test and 18 questions on diagnosis, treatment and socio-demographics were included. A D-efficient design with priors was used. Analyses used a mixed logit regression model with random effects. 3 inhaler profiles were of particular interest: Inhaler A - soft mist inhaler, Inhaler B - single dose dry powder inhaler Inhaler C – multi-dose dry powder inhaler. 153 patients (50 females) with a self-reported COPD stage of 2-4 completed the study. Respondents were 50.4 years old on average, using 13 different inhaler devices. Statistically significant results show that L-shaped inhalers, dose preparation with capsule insertion, inhalers with a dose counter and re-usable inhalers were preferred. Pre-filled inhalers were also preferred versus inhalers requiring cartridge or capsule insertion, with borderline significance. Inhaler A and Inhaler A as a reusable device inhaler profiles had the highest utility (mean of 1.2533 and 0.9578 respectively) compared to inhaler B (0.2200) and inhaler C (0.6315). The results show that a number of convenience-related inhaler characteristics are strong drivers of COPD patient preference in France and should be taken into account by clinicians prescribing these devices.

Microbiological monitoring of medical devices after cleaning, disinfection and sterilisation

The use of reusable semi-critical devices has been extended in current medical practice for both diagnostic and therapeutic purposes. However, reuse of these instruments carries the risk of cross-transmission of microorganisms from one patient to another. The process of cleaning and disinfecting these devices is complex, long, expensive and very error-prone. This paper analyses the epidemiological aspects of infections associated with the reuse of semi-critical devices and the role of the Microbiology laboratory in monitoring the cleaning and disinfecting process through microbiological controls. The recommendations of different scientific societies on the relevance of such controls are reviewed and specific recommendations are proposed for the taking and processing of the samples, interpretation of the results and measures to be taken depending on the results obtained.

A test method to assess the contribution of fluid shear stress to the cleaning of reusable device surfaces.

Adequate cleaning of reusable medical devices is critical for preventing cross-infection among patients. For reusable medical devices, cleaning using mechanical brushes and detergent may not be sufficient to completely remove the infectious contaminants from the surfaces. This study evaluates the role of fluid flow-induced shear stress in the detachment and removal of contaminants from device surfaces. A stainless-steel test coupon, acting as a surrogate for a device surface, was coated with artificial clot of varying mass. The test coupon was exposed to fluid shear stress both with and without an enzymatic detergent. The relationship between clot removal quantity and the applied shear stress was obtained for multiple clot masses. Our results showed that fluid shear increased the effectiveness of the cleaning process. In the absence of flow, soaking the clot surface in the enzymatic detergent removed 67%, 77%, and 95% of the clot for 16 mg, 6.8 mg, and 1 mg initial masses, respectively. In the presence of fluid shear (0.3 Pa for 5 min), approximately 85%, 97%, and 99% of the clot was removed from the surface. The clot mass removed followed a linear relationship (R2 = 0.98) versus the applied fluid shear stress. This study showed that different cleaning processes such as fluid shear and detergent action contribute to the soil removal process. This method could be used to evaluate cleaning protocols for minimizing contaminant residue after the reprocessing of medical devices. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1132-1140, 2019.

Single-use bronchoscopes less costly than reusable devices

Single-use bronchoscopes less costly than reusable devices

Development of an end-effector device for loose body removal in hip arthroscopy.

This article describes a novel hand-operated end-effector device developed for loose body removal in hip arthroscopy. This sterilizable and reusable device incorporates a wire-ball joint mechanism that provides motion with 5 degrees of freedom. The design accounted for the following: (1) the diameter of the femoral head, (2) range of motion of the wrist joint of the operator, (3) ease of assembly of modular parts, and (4) material stiffness and durability. The developed device is composed of three parts: a pistol-shaped hand-held unit, forceps module, and end-effector module, all of which were constructed using polyamide-imide. Experiments were conducted to characterize the range of motion, pushing force, and lateral stiffness of the end-effector. Seven consulting surgeons evaluated the performance of the device in arthroscopic hip model and cadaveric studies in comparison with that of a conventional linear grasper. The experimental results show that the developed device can perform tasks that conventional linear graspers cannot. A specialized end-effector device was developed for hip arthroscopy where a high degree of stiffness is required. The end-effector module is interchangeable based on the required outer diameter, and it is also reusable after sterilization at high temperature.

Assessing the efficacy and cost of detergents used in a primary care automated washer disinfector.

Cleaning of re-usable medical devices is a critical control point in the decontamination cycle, although defined end-points of the process are controversial. Investigate cleaning efficacy and cost of different detergent classes in an automated washer disinfector (AWD) designed for dental practice. Loads comprised test soiled dental hand instruments in cassettes and extraction forceps. Residual protein assayed using the International standard method (ISO 15883-5:2005) 1% SDS elution with ortho-phthalaldehyde (OPA) or GBox technology (on instrument OPA analysis). Short (60 minutes) and long (97 minutes) AWD cycles were used with four different classes of detergents, tap water and reverse osmosis water. SDS elution analysis (N = 612 instruments) demonstrated four detergents with both wash cycles achieved equivalent cleanliness levels and below a threshold of 200 μg protein/instrument. GBox methodology (N = 575) using UK Department of Health threshold of 5 μg/instrument side demonstrated that tap water performed with the greatest efficacy for all types of instruments and cycle types. Using International standard methodology, different detergent classes had equivalence in cleaning efficacy. Cheaper detergents used in this study performed with similar efficacy to more expensive solutions. Findings emphasise the importance of validating the detergent (type and concentration) for each AWD.

Life Cycle Assessment and Costing Methods for Device Procurement: Comparing Reusable and Single-Use Disposable Laryngoscopes.

Traditional medical device procurement criteria include efficacy and safety, ease of use and handling, and procurement costs. However, little information is available about life cycle environmental impacts of the production, use, and disposal of medical devices, or about costs incurred after purchase. Reusable and disposable laryngoscopes are of current interest to anesthesiologists. Facing mounting pressure to quickly meet or exceed conflicting infection prevention guidelines and oversight body recommendations, many institutions may be electively switching to single-use disposable (SUD) rigid laryngoscopes or overcleaning reusables, potentially increasing both costs and waste generation. This study provides quantitative comparisons of environmental impacts and total cost of ownership among laryngoscope options, which can aid procurement decision making to benefit facilities and public health. We describe cradle-to-grave life cycle assessment (LCA) and life cycle costing (LCC) methods and apply these to reusable and SUD metal and plastic laryngoscope handles and tongue blade alternatives at Yale-New Haven Hospital (YNHH). The US Environmental Protection Agency's Tool for the Reduction and Assessment of Chemical and other environmental Impacts (TRACI) life cycle impact assessment method was used to model environmental impacts of greenhouse gases and other pollutant emissions. The SUD plastic handle generates an estimated 16-18 times more life cycle carbon dioxide equivalents (CO2-eq) than traditional low-level disinfection of the reusable steel handle. The SUD plastic tongue blade generates an estimated 5-6 times more CO2-eq than the reusable steel blade treated with high-level disinfection. SUD metal components generated much higher emissions than all alternatives. Both the SUD handle and SUD blade increased life cycle costs compared to the various reusable cleaning scenarios at YNHH. When extrapolated over 1 year (60,000 intubations), estimated costs increased between $495,000 and $604,000 for SUD handles and between $180,000 and $265,000 for SUD blades, compared to reusables, depending on cleaning scenario and assuming 4000 (rated) uses. Considering device attrition, reusable handles would be more economical than SUDs if they last through 4-5 uses, and reusable blades 5-7 uses, before loss. LCA and LCC are feasible methods to ease interpretation of environmental impacts and facility costs when weighing device procurement options. While management practices vary between institutions, all standard methods of cleaning were evaluated and sensitivity analyses performed so that results are widely applicable. For YNHH, the reusable options presented a considerable cost advantage, in addition to offering a better option environmentally. Avoiding overcleaning reusable laryngoscope handles and blades is desirable from an environmental perspective. Costs may vary between facilities, and LCC methodology demonstrates the importance of time-motion labor analysis when comparing reusable and disposable device options.

Production of patient-specific electron beam aperture cut-outs using a low-cost, multi-purpose 3D printer.

Electron beam collimators for non‐standard field sizes and shapes are typically fabricated using Styrofoam molds to cast the aperture cut‐out. These molds are often produced using a dedicated foam cutter, which may be expensive and only serves a single purpose. An increasing number of radiotherapy departments, however, has a 3D printer on‐site, to create a wide range of custom‐made treatment auxiliaries, such as bolus and dosimetry phantoms. The 3D printer can also be used to produce patient‐specific aperture cut‐outs, as elaborated in this note. Open‐source programming language was used to automatically generate the mold's shape in a generic digital file format readable by 3D printer software. The geometric mold model has the patient's identification number integrated and is to be mounted on a uniquely fitting, reusable positioning device, which can be 3D printed as well. This assembly likewise fits uniquely onto the applicator tray, ensuring correct and error‐free alignment of the mold during casting of the aperture. For dosimetric verification, two aperture cut‐outs were cast, one using a conventionally cut Styrofoam mold and one using a 3D printed mold. Using these cut‐outs, the clinical plan was delivered onto a phantom, for which the transversal dose distributions were measured at 2 cm depth using radiochromic film and compared using gamma‐index analysis. An agreement score of 99.9% between the measured 2D dose distributions was found in the (10%–80%) dose region, using 1% (local) dose‐difference and 1.0 mm distance‐to‐agreement acceptance criteria. The workflow using 3D printing has been clinically implemented and is in routine use at the author's institute for all patient‐specific electron beam aperture cut‐outs. It allows for a standardized, cost‐effective, and operator‐friendly workflow without the need for dedicated equipment. In addition, it offers possibilities to increase safety and quality of the process including patient identification and methods for accurate mold alignment.

Instrument processing knowledge and practice amongst healthcare workers in Addis Ababa, Ethiopia

The recent outbreaks of healthcare associated infections (HAIs) as a result of poor cleaning, disinfection and sterilization of medical equipment, and concerns about the possible spread of highly contagious infections has brought the issue of instrument processing in the fore front of infection prevention. Conversely, in many developing countries such as Ethiopia instrument processing practice (IPP) among healthcare workers (HCWs) is not quantified yet. A cross-sectional study was conducted to assess HCWs instrument processing practice and associated factors in health centers of Addis Ababa, Ethiopia in January, 2017. Simple random sampling technique was employed to select 328 HCWs. Data was collected using structured questioner and checklist. Univariate analysis, binary and multivariate logistic regression was computed. Adjusted odds ratio (AOR) with corresponding 95% confidence interval (CI) was used to quantify the strength of association and p-value ≤ 0.05 was used to declare statistical significance. Less than half 46.3% (95%CI: 40.9, 51.5) of HCWs are knowledgeable on instrument processing and 220(67.1%) (95%CI: 61.9, 71.6) of HCWs had safe IPP. High risk perception towards transmitting an infection while working (AOR: 5.35; 95%CI: 2.44, 11.73), being knowledgeable on instrument processing (AOR: 2.81; 95%CI: 1.50, 5.27), and having positive attitude towards infection prevention (AOR: 2.39; 95%CI: 1.19, 4.84) were the most important variables associated with safe IPP. In general, HCWs instrument processing practice was not safe enough. Moreover, significant number of HCWs lacks adequate instrument processing knowledge. Hence, enhancing HCWs awareness on IPP should be undertaken along with urgent improvement in routine monitoring of autoclaves. Keywords: Instrument processing; Decontamination; Cleaning; Sterilization; Disinfection; Reusable medical devices; Ethiopia

A microfluidic surface-enhanced Raman spectroscopy approach for assessing the particle number effect of AgNPs on cytotoxicity

Silver nanoparticles (Ag NPs) have well-known antibacterial properties and are widely applied in various medical products and general commodities. Although many studies have addressed the toxicity of Ag NPs to mammalian cells, the direct relationship between the number of Ag NPs in living cells and the corresponding cell toxicity has not yet been explicitly demonstrated. In this work, a simple and reusable microfluidic device composed of a quartz cover slip and a glass plate with etched micro-channel and micro-wells was employed for separating and trapping single living cells. The device was silanized to render the surface hydrophobic. For simplicity, HeLa cells as the model cancer cells were used in the study, which were pipette-loaded into an array of micro wells based on dead-end filling. Surface enhanced Raman spectroscopy (SERS) was then employed to examine the living cancer cells and assessed number and distribution of Ag NPs in the cells. Combined with the cell viability assay, we therefore correlated the number of Ag NPs in the cell with the toxicity to the cell directly.

A Reusable Cap for Disposable Insulin Pens Protects Insulin against Temperature-Induced Degradation

Insulin has to be kept at 4-8° C (∼ 39°F to 47°F) until use and once opened, is supposed to be stable for 28 to 30 days at room temperature. Exposure to extreme cold or heat leads to insulin degradation in a very short time with loss of glucose-lowering efficacy. ViVi-Cap (TempraMed Inc.) is a reusable storage device, which is available for all existing disposable pen devices in the U.S. and EU. It works without external power supply requirements based on an ultra-high vacuum insulation and an additional heat consumption by a calorimetry-based phase-change technology. Five disposable insulin pens (FlexPen, Insulin aspart) were kept for one week under extreme temperature conditions for 5 days (each day: 8 h at 50 °C and 16 h at 22 °C) either without protection, in a frio device (freshly prepared each day) and in the ViViCap. Samples were taken every day and insulin degradation was determined in accordance with U.S. pharmacopoia by appropriate HPLC methods for insulin aspart, and high and low molecular weight degradation molecules. Each experiment was performed in triplicate. Insulin aspart without protection was shown to have more than 2% impurities already after one day (Frio: 2 days, ViViCap: >5 days). High molecular weight products appeared in measurable quantities after two days without protection (Frio: 3 days, ViViCap > 5 days, p<0.01 against the other 2 storage conditions). ViVi-Cap was superior to the other tested conditions with respect to stabilizing insulin aspart during storage under extreme temperature conditions. The device provides an easy to use solution for maintaining insulin efficacy under daily life conditions. Disclosure A. Pfützner: Advisory Panel; Self; Novo Nordisk A/S, Sanofi. Consultant; Self; Lifecare. Speaker's Bureau; Self; Berlin-Chemie AG. Research Support; Self; Boehringer Ingelheim GmbH. R. Nagar: Stock/Shareholder; Self; TempraMed Ltd.. W. Reeh: None.

Cellulose membrane modified with polypyrrole as an extraction device for the determination of emerging contaminants in river water with gas chromatography–mass spectrometry

In this study, a simple, efficient, and reusable device based on cellulose membranes modified with polypyrrole was developed to extract 14 emerging contaminants from aqueous matrices. For chemical polymerization, a low-cost cellulose membrane was immersed in 0.1mol/L pyrrole and 0.5mol/L ammonium persulfate for 40min in an ice/water bath. The cellulose membranes modified with polypyrrole were accommodated in a polycarbonate holder suitable for solid-phase extraction disks. Solid-phase extraction parameters that affect extraction efficiency, such as sample volume, pH, flow rate, and desorption were optimized. Subsequently, determination of target compounds was performed by gas chromatography with mass spectrometry. The linear range for analytes ranged from 0.05 to 500 μg/L, with coefficients of determination above 0.990. The limits of quantification varied between 0.05 and 10 μg/L, with relative standard deviations lower than 17%. The performance of the proposed cellulose membranes modified with polypyrrole device for real samples was evaluated after extraction of emerging contaminants from a river water sample from the city of Curitiba, Brazil. Bisphenol A (6.39 μg/L), caffeine (17.83 μg/L), and paracetamol (19.28 μg/L) were found in these samples.

Miniature Negative Pressure Dressings on Forearm Donor Sites after Radial Forearm Flap Harvest.

Summary:Management of radial forearm donor sites following free flap reconstruction of head and neck tumor defects typically requires split-thickness skin grafting. Tendon exposure and delayed healing are occasional problems associated with skin grafting over the distal forearm musculature. Others have reported the use of negative pressure wound therapy (NPWT) devices to bolster split-thickness grafts and improve graft take. Although this approach works well, these devices are not always approved by third-party payers for outpatient use, requiring patients to remain in the hospital or have these devices removed before discharge. The authors report outcomes using a miniaturized NPWT device to bolster the skin graft on radial forearm free flap donor sites in 10 consecutive patients compared with 10 consecutive control patients managed with traditional bolster dressings. The 2 groups of patients were similar in terms of demographics, indication for reconstruction, and size of donor site. There was less skin graft loss and a lower rate of tendon exposure and infection in the miniaturized NPWT device group, though these results did not reach statistical significance. Recently developed miniaturized, single-use NPWT devices can be reliably used as bolsters for skin grafts with some notable advantages over reusable NPWT devices.

Enzyme-Regulated DNA-Based Logic Device.

Herein, we report a carbazole (Cz) ligand that displays distinct turn-on fluorescence signals upon interaction with human telomeric G-quadruplex ( h-TELO) and nuclease enzymes. Interestingly, Cz selectively binds and stabilizes the mixed hybrid topology of h-TELO G-quadruplex that withstands digestion by exonucleases and nuclease S1. The distinct fluorescence signatures of Cz-stabilized h-TELO with nucleases are used to design conceptually novel DNA devices for selectively detecting the enzymatic activity of DNase I as well as performing logic operations. An INHIBIT logic gate is constructed using h-TELO and DNase I as the inputs while the inputs of h-TELO and nuclease S1 form a YES logic gate. Furthermore, a two-input two-output reusable logic device with "multireset" function is developed by using h-TELO and DNase I as inputs. On the basis of this platform, combinatorial logic systems (INHIBIT-INHIBIT and NOR-OR) have been successfully installed using different combinations of nucleases as inputs. Moreover, this new strategy of using a synthetic dual emissive probe and enzyme/DNA inputs for constructing reusable logic device may find important applications in biological computing and information processing.

Import Substitution Possibilities in Palliative Medicine

Nutrition is an important problem of palliative care. If oral feeding is not possible, percutaneous endoscopic gastrostomy (PEG) is the method of choice. The wide application of the procedure is limited by the cost of single-use sets produced in other countries. The aim of the study was to review methodic of the PEG and to find an opportunity to reduce its cost. A reusable device was developed for the application of the PEG with use of a Pétzzer catheter. Approbation of the device and methodic was carried out in experiment with 10 rabbits. In 2 cases animals died on the 5th and 6th day after the operation because of acute pneumonia and enterocolitis, complications from the operating wound and gastrostomy were absent. Remaining 8 rabbits were withdrawn from the experiment on the 10-13 day after the operation. In 3 cases purulent infection of the postoperative wound and formation of abscesses of abdominal cavity were revealed, while the gastrostomic fistula was without any signs of failure. In 5 cases were no complications. The gastrostomic fistula was placed next to laparotomic wound and was not complicated in all cases. All the described complications are considered to features of laparotomy and postoperative period in animals. The constructed analogue of the PEG allow significantly reduce costs and increase the economic efficiency of minimally invasive gastrostomy, reduce dependence on foreign materials. Encouraging results obtained in animal experiments allow testing of the technique in clinical settings.