Biofilms in device-related infections

The use of various medical devices including indwelling vascular catheters, cardiac pacemakers, prosthetic heart valves, chronic ambulatory peritoneal dialysis catheters and prosthetic joints has greatly facilitated the management of serious medical and surgical illness. However, the successful development of synthetic materials and introduction of these artificial devices into various body systems has been accompanied by the ability of microorganisms to adhere to these devices in the environment of biofilms that protect them from the activity of antimicrobial agents and from host defense mechanisms. A number of host, biomaterial and microbial factors are unique to the initiation, persistence and treatment failures of device-related infections. Intravascular catheters are the most common devices used in clinical practice and interactions associated with these devices are the leading cause of nosocomial bacteremias. The infections associated with these devices include insertion site infection, septic thrombophlebitis, septicemia, endocarditis and metastatic abscesses. Other important device-related infections include infections of vascular prostheses, intracardiac prostheses, total artificial hearts, indwelling urinary catheters, orthopedic prostheses, endotracheal tubes and extended wear lenses. The diagnosis and management of biofilm-associated infections remain difficult but critical issues. Appropriate antimicrobial therapy is often not effective in eradicating these infections and the removal of the device becomes necessary. Several improved diagnostic and therapeutic modalities have been reported in recent experimental studies. The clinical usefulness of these strategies remains to be determined.     

医院医疗器械维修中存在的问题及维修管理对策研究

近几年来,随着科学技术的发展和医院规模的扩大,社会对医疗技术要求不断提高,因此,高端医疗器械和新型医疗设备需求加大,医疗器械管理与维修也需跟进。医疗器械的正常使用在医疗工作中有着举足轻重的作用,可提高医疗人员的工作效率,提升临床诊治的水平,但其在改善医疗条件的同时也存在一系列的问题,若无法保质和及时维修医疗器械,对正常医疗设备的使用具有严重影响,延误患者的就诊与治疗。目前医院医疗器械维修中存在的维修人员整体素质偏低、管理机制不健全、维修技术落后、医疗器械维修人员不足、缺乏积极性及再学习的机会、医疗器械缺乏定期保养和管理等实际问题,导致医疗器械维修效率低,本文就以上问题展开讨论,旨在为医院维修管理的制定提供参考。     

新一代医用刚质聚合物外科植入动物实验研究

目的:研究新一代医用刚质聚合物的植入动物后的变化情况,方法:根据美国材料协会(ASTM)标准中有关用于外科植入的聚合物材料相容性评价实施标准,对新一代医用刚质聚合物进行外科植入动物试验。结果:试验样品和对照样品周围组织出现的变化同步。结果:新一代刚质聚合物与已在临床上应用的聚合物具有相同的生物相容性。同样可作为人工材料应用于临床。     

人工膜肺氧合器临床应用研究及发展趋势

本文综述目前我国膜式氧合器临床应用,人工膜肺领域的研究成果和发展趋势。通过问卷调查形式显示我国近年CPB （Cardiopulmonary Bypass,体外循环）技术发展迅速,膜式氧合器应用量逐年升高,应用ECMO（extracorporeal membrane oxygenation, 体外膜肺氧合）辅助循环的比例显著增加。人工膜肺多方面研究进展包括：为新生儿体外循环设计的婴幼儿膜式氧合器,整合 动脉滤过器与超滤设备的小型化氧合器,这些设计可以明显减少体外循环回路整体表面积和预充量,避免CPB 中过度血液稀释, 降低或不用输入红细胞。同时减轻由于血液与人工材料接触诱发的炎性反应。人工膜肺在人工材料改进和结构设计有很显著发 展,通过改进气体交换的人工膜材料,优化结构设计,提高血液抗凝能力和耐受力,设计出如ECMO 可以长时间应用于辅助循环 来延续和支持病人的生命。对膜式氧合器的试验研究的相关进展和展望也会在本文讨论。     

Ottawa researchers enter home stretch in race to produce artificial heart

An Ottawa team is in a fierce race to produce an artificial heart. If it wins, the prize will be huge: a worldwide market worth billions of dollars. The team, led by Dr. Tofy Mussivand, brings together scientists and entrepreneurs. The goal is to produce a heart that improves patients'' quality of life and doesn''t leave them tethered to a machine in hospital. Current plans are to complete clinical tests by 2000 and to have a commercial product ready for market in 2001-2. Several other groups are also racing the clock.     

Modified procedure for implantation of subcutaneous central venous access devices in macaques (Macaca mulatta)

A nonhuman primate model comprising adult male rhesus monkeys (Macaca mulatta) with chronically indwelling subcutaneous central venous access devices provides a unique opportunity to determine plasma pharmacokinetics of new drugs such as anticancer and anti- retroviral agents. The central venous access we use is a low-profile, single-septum, titanium port that is attached to a radiopaque, indwelling catheter; the catheter is implanted in an internal jugular vein. A common complication following placement of the venous access device was migration of the catheter tip. We therefore modified the standard procedure by cutting the silicone catheter and introducing the rigid connector to secure the catheter to the vessel at the insertion site (approximately 9 to 13 cm from the distal end of the catheter). Prior to the use of the connector, three of five catheters migrated within 4 weeks after placement. In contrast, all 13 internal jugular catheters with connectors have remained patent without migration of the catheter tip. Therefore, incorporation of the catheter connector appears to have eliminated the problem of catheter migration.     

Construction of covalently coupled,concatameric dimers of 7TM receptors

7TM receptors are easily fused to proteins such as G proteins and arrestin but because of the fact that their terminals are found on each side of the membrane they cannot be joined directly in covalent dimers. Here, we use an artificial connector comprising a transmembrane helix composed of Leu-Ala repeats flanked by flexible spacers and positively charged residues to ensure correct inside-out orientation plus an extracellular HA-tag to construct covalently coupled dimers of 7TM receptors. Such 15 TM concatameric homo- and heterodimers of the β₂-adrenergic and the NK₁ receptors, which normally do not dimerize with each other, were expressed surprisingly well at the cell surface, where they bound ligands and activated signal transduction in a manner rather similar to the corresponding wild-type receptors. The concatameric heterodimers internalized upon stimulation with agonists for either of the protomers, which was not observed upon simple coexpression of the two receptors. It is concluded that covalently joined 7TM receptor dimers with surprisingly normal receptor properties can be constructed with use of an artificial transmembrane connector, which perhaps can be used to fuse other membrane proteins.     

Design and implementation of an integrated management system in a plant factory to save energy

Recently, various studies have been conducted to stabilize food production and improve product quality and energy saving efficiency in the face of climate change by integrating ICT (Information and Communication Technology) into existing agricultural technologies. A representative example of this technology, the fully artificial plant factory, facilitates a high degree of environment control and growth prediction based on the cultivation environment and monitoring of crop growth, and has the advantage that environment-friendly crops are cultured. However, the concept has met difficulties in entering the market due to the large investment in facilities and expensive operation costs involved. There are many considerations, including calculating the optimal environment parameters for plants, designing and controlling artificial lights characterized by high-level efficiency and low power consumption, and selecting value-added crops. Among others parameters, those of the optimal environment may be utilized as a very important input element for maximizing plant growth and minimizing energy injection costs. To this end, data, including those related to environment, growth, and energy, will be monitored in real time, and integration management systems will be developed in advance to realize the effective control of connected devices based on the concept of the fully artificial plant factory. However, existing systems are designed for horticultural facilities and have been operated by simply monitoring environment or growth information or individually controlling each device through different interface environments, without considering the energy consumption of the devices. The purpose of this study is to design a method for monitoring in real time integrated environment and growth data and the energy consumption of the devices in a fully artificial plant factory, and to design and implement a plant factory integration management system that actively controls devices based on these data. In the future, the environment/growth/energy data collected from sensors in the proposed system will allow the optimal environment parameters to be calculated for each crop through correlation analysis and each device to be integrated and controlled, contributing to an increase in crop productivity and quality, as well as overall energy consumption efficiency in the plant factory. In addition, the database information collected from the system and then processed will be useful as input data for the integrated database of the SSN (Social Sensor Network) or the intelligent plant factory system.     

Withholding the artificial administration of fluids and food from elderly patients with dementia: ethnographic study

ObjectiveTo clarify the practice of withholding the artificial administration of fluids and food from elderly patients with dementia in nursing homes.DesignQualitative, ethnographic study in two phases.Setting10 wards in two nursing homes in the Netherlands.Participants35 patients with dementia, eight doctors, 43 nurses, and 32 families.ResultsThe clinical course of dementia was considered normal and was rarely reason to begin the artificial administration of fluids and food in advanced disease. Fluids and food seemed to be given mainly when there was an acute illness or a condition that needed medical treatment and which required hydration to be effective. The medical condition of the patient, the wishes of the family, and the interpretations of the patients'' quality of life by their care providers were considered more important than living wills and policy agreements.ConclusionsDoctors'' decisions about withholding the artificial administration of fluids and food from elderly patients with dementia are influenced more by the clinical course of the illness, the presumed quality of life of the patient, and the patient''s medical condition than they are by advanced planning of care. In an attempt to understand the wishes of the patient doctors try to create the broadest possible basis for the decision making process and its outcome, mainly by involving the family.

What is already known on this topic

Debate has focused on whether it is beneficial to withhold the artificial administration of fluids and food from patients with advanced dementia

What this study adds

The course of dementia, the patient''s quality of life, and the patient''s current medical condition influence doctors'' decision making more than advanced planning of careDoctors try to create the broadest possible basis for the decision making process and its outcome, mainly by involving the family     

Adaptive mining prediction model for content recommendation to coronary heart disease patients

This paper proposes the Fuzzy Rule-based Adaptive Coronary Heart Disease Prediction Support Model (FbACHD_PSM), which gives content recommendation to coronary heart disease patients. The proposed model uses a mining technique validated by medical experts to provide recommendations. FbACHD_PSM consists of three parts for heart disease risk prediction. First, a fuzzy membership function is constructed using medical guidelines and statistical methods. Then, a decision-tree rule induction technique creates mining-based rules that are subjected to validation by medical experts. As the rules may not be medically suitable, the experts add rules that have been verified and delete inappropriate rules. Thirdly, using fuzzy inference based on Mamdani’s method, the model predicts the risk of heart disease. Based on this, final recommendations are provided to patients regarding normal living, nutrition control, exercise, and drugs. To implement our proposed model and evaluate its performance, we use a dataset from a single tertiary hospital.     

Implantation of Total Artificial Heart in Congenital Heart Disease

In patients with end-stage heart failure (HF), a total artificial heart (TAH) may be implanted as a bridge to cardiac transplant. However, in congenital heart disease (CHD), the malformed heart presents a challenge to TAH implantation. In the case presented here, a 17 year-old patient with congenital transposition of the great arteries (CCTGA) experienced progressively worsening HF due to his congenital condition. He was hospitalized multiple times and received an implantable cardioverter defibrillator (ICD). However, his condition soon deteriorated to end-stage HF with multisystem organ failure. Due to the patient''s grave clinical condition and the presence of complex cardiac lesions, the decision was made to proceed with a TAH. The abnormal arrangement of the patient''s ventricles and great arteries required modifications to the TAH during implantation.With the TAH in place, the patient was able to return home and regain strength and physical well-being while awaiting a donor heart. He was successfully bridged to heart transplantation 5 months after receiving the device. This report highlights the TAH is feasible even in patients with structurally abnormal hearts, with technical modification.     

Time's running out as physicians await Y2K fallout.

Canada''s hospitals are slowly coming to grips with the millennium bug, but Anita Elash reports that no one really knows what impact the move into the year 2000 will have on computers and medical devices, either in the hospital or doctor''s office.     

The Crystal Structure of Bacteriophage HK97 gp6: Defining a Large Family of Head-Tail Connector Proteins

The final step in the morphogenesis of long-tailed double-stranded DNA bacteriophages is the joining of the DNA-filled head to the tail. The connector is a specialized structure of the head that serves as the interface for tail attachment and the point of egress for DNA from the head during infection. Here, we report the determination of a 2.1 Å crystal structure of gp6 of bacteriophage HK97. Through structural comparisons, functional studies, and bioinformatic analysis, gp6 has been determined to be a component of the connector of phage HK97 that is evolutionarily related to gp15, a well-characterized connector component of bacteriophage SPP1. Whereas the structure of gp15 was solved in a monomeric form, gp6 crystallized as an oligomeric ring with the dimensions expected for a connector protein. Although this ring is composed of 13 subunits, which does not match the symmetry of the connector within the phage, sequence conservation and modeling of this structure into the cryo-electron microscopy density of the SPP1 connector indicate that this oligomeric structure represents the arrangement of gp6 subunits within the mature phage particle. Through sequence searches and genomic position analysis, we determined that gp6 is a member of a large family of connector proteins that are present in long-tailed phages. We have also identified gp7 of HK97 as a homologue of gp16 of phage SPP1, which is the second component of the connector of this phage. These proteins are members of another large protein family involved in connector assembly.     

Heart valve prosthesis, anticoagulants and pregnancy

Patients with artificial valve prostheses require lifelong anticoagulation treatment. The risk of thrombotic complications increases greatly in pregnancy. Anticoagulant treatment in pregnant women with artificial heart valve prostheses in one of the most controversial problems in medical practice as anticoagulants which are beneficial and safe for the mother may by hazardous for the fetus. Recommended procedure is to administer heparin subcutaneously at last during the first 14 weeks and the last 2 weeks of gestation and coumarin derivates throughout the second and third trimesters. In asymptomatic or mildly symptomatic women who are willing to follow a strict regimen of antithrombotic prophylaxis in pregnancy the risk is not associated with an increased morbidity or mortality in the mother or fetus. Hence, recommendations against pregnancy in women with artificial heart valves are not always justified.     

Integrated data acquisition system for medical device testing and physiology research in compliance with good laboratory practices

In seeking approval from the US Food and Drug Administration (FDA) for clinical trial evaluation of an experimental medical device, a sponsor is required to submit experimental findings and support documentation to demonstrate device safety and efficacy that are in compliance with Good Laboratory Practices (GLP). The objective of this project was to develop an integrated data acquisition (DAQ) system and documentation strategy for monitoring and recording physiological data when testing medical devices in accordance with GLP guidelines mandated by the FDA. Data aquisition systems were developed as stand-alone instrumentation racks containing transducer amplifiers and signal processors, analog-to-digital converters for data storage, visual display and graphical user-interfaces, power conditioners, and test measurement devices. Engineering standard operating procedures (SOP) were developed to provide a written step-by-step process for calibrating, validating, and certifying each individual instrumentation unit and the integrated DAQ system. Engineering staff received GLP and SOP training and then completed the calibration, validation, and certification process for the individual instrumentation components and integrated DAQ system. Eight integrated DAQ systems have been successfully developed that were inspected by regulatory affairs consultants and determined to meet GLP guidelines. Two of these DAQ systems were used to support 40 of the pre-clinical animal studies evaluating the AbiCor artificial heart (ABIOMED, Danvers, MA). Based in part on these pre-clinical animal data, the AbioCor clinical trials began in July 2001. The process of developing integrated DAQ systems, SOP, and the validation and certification methods used to ensure GLP compliance are presented in this article.     

Binding of pRNA to the N-terminal 14 amino acids of connector protein of bacteriophage phi29

During assembly, bacterial virus phi29 utilizes a motor to insert genomic DNA into a preformed protein shell called the procapsid. The motor contains one twelve-subunit connector with a 3.6 nm central channel for DNA transportation, six viral-encoded RNA (packaging RNA or pRNA) and a protein, gp16, with unknown stoichiometry. Recent DNA-packaging models proposed that the 5-fold procapsid vertexes and 12-fold connector (or the hexameric pRNA ring) represented a symmetry mismatch enabling production of a force to drive a rotation motor to translocate and compress DNA. There was a discrepancy regarding the location of the foothold for the pRNA. One model [C. Chen and P. Guo (1997) J. Virol., 71, 3864–3871] suggested that the foothold for pRNA was the connector and that the pRNA–connector complex was part of the rotor. However, one other model suggested that the foothold for pRNA was the 5-fold vertex of the capsid protein and that pRNA was the stator. To elucidate the mechanism of phi29 DNA packaging, it is critical to confirm whether pRNA binds to the 5-fold vertex of the capsid protein or to the 12-fold symmetrical connector. Here, we used both purified connector and purified procapsid for binding studies with in vitro transcribed pRNA. Specific binding of pRNA to the connector in the procapsid was found by photoaffinity crosslinking. Removal of the N-terminal 14 amino acids of the gp10 protein by proteolytic cleavage resulted in undetectable binding of pRNA to either the connector or the procapsid, as investigated by agarose gel electrophoresis, SDS–PAGE, sucrose gradient sedimentation and N-terminal peptide sequencing. It is therefore concluded that pRNA bound to the 12-fold symmetrical connector to form a pRNA–connector complex and that the foothold for pRNA is the connector but not the capsid protein.     

Evaluation of a Novel Laser-assisted Coronary Anastomotic Connector - the Trinity Clip - in a Porcine Off-pump Bypass Model

To simplify and facilitate beating heart (i.e., off-pump), minimally invasive coronary artery bypass surgery, a new coronary anastomotic connector, the Trinity Clip, is developed based on the excimer laser-assisted nonocclusive anastomosis technique. The Trinity Clip connector enables simplified, sutureless, and nonocclusive connection of the graft to the coronary artery, and an excimer laser catheter laser-punches the opening of the anastomosis. Consequently, owing to the complete nonocclusive anastomosis construction, coronary conditioning (i.e., occluding or shunting) is not necessary, in contrast to the conventional anastomotic technique, hence simplifying the off-pump bypass procedure. Prior to clinical application in coronary artery bypass grafting, the safety and quality of this novel connector will be evaluated in a long-term experimental porcine off-pump coronary artery bypass (OPCAB) study. In this paper, we describe how to evaluate the coronary anastomosis in the porcine OPCAB model using various techniques to assess its quality. Representative results are summarized and visually demonstrated.     

自制起搏电极在心脏电生理实验中的应用研究

本文探索了自制起搏电极在心脏电生理研究中的应用,通过选择适当的材料,分为三部分制作电极：极片部分、起搏器接口部分、焊封与绝缘。最后,将电极缝合于犬的心脏进行起搏。结论是自制起搏电极应用于动物实验进行心脏电生理的研究是可行的。     

Cardiovascular State of Newly Discovered Diabetic Women

A cardiovascular study of a group of 90 newly diagnosed diabetic women aged 35 to 75 years was begun in 1965 and a repeat examination was carried out on the same patients in 1968. A high prevalence of ischaemic heart disease was found in these patients at the time of diagnosis, and this finding had some predictive value as regards prognosis over the three-year period.A comparative study with general medical outpatients and long-established diabetics (greater than 10 years'' duration of disease) confirmed the high prevalence of ischaemic heart disease in late-onset mild diabetics controlled by diet or oral drugs. It is suggested that this type of milder diabetic patient contributes in undue proportion to the high prevalence of ischaemic heart disease in diabetes.