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Degradable and injectable poly(aldehyde guluronate) hydrogels for bone tissue engineering.

Degradable and injectable hydrogels may be ideal for bone-tissue engineering, especially in the craniofacial region because of the ease of access for injection. Alginate hydrogels potentially could be used as injectable cell delivery vehicles, but they exhibit a limited range of mechanical properties and uncontrollable disintegration time. Therefore we synthesized new hydrogels, composed of poly(aldehyde guluronate) (PAG) and adipic acid dihydrazide, that have a wide range of mechanical stiffness and controllable degradation rate. MC3T3-E1 cells adhered and multiplied on PAG hydrogels in vitro. When primary rat calvarial osteoblasts were mixed with PAG hydrogels and subcutaneously injected into the backs of mice, mineralized bone tissues were formed 9 weeks following implantation. These hydrogels may find wide utility as an injectable delivery system for bone precursor cells as well as for other applications in tissue engineering.

3T3 Cells↗

Certification of clinical engineers.

This paper constitutes a review of the certification process for Clinical Engineers, and specifically the nature and activities of the National Certification Commission. It describes written and oral certification examinations, and the working relationship between the Board of Examiners and the National Board of the Commission. This paper discusses BMET Certification and its relationship to the central role of Clinical Engineers. The need for Certification is stressed and its effect on the quality of health care is discussed.

Biomedical Engineering↗

The future of clinical engineering: technology that enables improved patient care.

Speakers at this year's ACCE Symposium will describe in detail the scope and depth of technological and other factors that are at work changing the healthcare delivery paradigm. Other presenters will explore the impact the changes will likely have on the clinical engineering profession. Still others will outline the steps necessary for clinical engineers to take to effectively prepare for the challenges facing them. The experts agree: clinical engineering is at a critical crossroads. No one who intends to pursue clinical engineering or healthcare technology management over the next 10 years can afford to miss this year's meeting.

Biomedical Engineering↗

[The cell micro-encapsulation techniques and its advancement in the field of gene therapy].

It is no doubt that the gene therapy using recombinant engineering cells provides a novel approach to many refractory diseases. However, the transplant rejection from the host's immune system against heterogeneous cells has been the main handicap of its clinical application. The modern cell micro-encapsulation technique with good immune isolation makes it possible to overcome this problem and has shown potential application foreground in clinical therapies for a lot of diseases such as Parkinson's disease and Hemophiliac disease. This article reviews mainly the relative materials and techniques in processing micro-encapsulation, the host cells used to construct the recombinant genetic engineering cells and application of cell micro-encapsulation technique in the field of gene therapy.

Biomedical Engineering↗

Microscopical imaging of hydroxyapatite/mica composite and packed hydroxyapatite structure--an atomic force microscopy investigation.

A fine grained hydroxyapatite/mica composite material was studied by the atomic force microscopy method and the results were compared with results of atomic force microscopy studies of very five grained hydroxyapatite. In the investigation it was found that the fractal dimension diagram from the atomic force microscopy studies is a tool by which mechanical properties on the surface of the material can be predicted. The two investigated materials were found to show self-similarity properties, i.e., they are identical on the surface. The information given by the fractal dimension is important, and the fractal dimension analysis is an important tool in future designing and engineering of, especially, bioceramics and composites.

Aluminum Silicates↗

Medical equipment planning.

Healthcare providers worldwide are facing an increasingly competitive environment and, in response, are downsizing to reduce costs and improve efficiency. Providers that are unable or unwilling to become more efficient will close. To stay in business, healthcare institutions must consider the cost of medical equipment and plan accordingly. Policies based on sound principles and experience prevent costly and/or harmful mistakes. In this article, we discuss the different phases of equipment planning, detail some of the relevant concepts and terminology, describe how clinical engineers can become involved, and highlight ECRI resources available to those carrying out the process. Whether you are a clinical engineer facing downsizing and consolidation, a healthcare administrator with a mandate to rein in the costs of technology, or a minister of health facing the task of building or maintaining a nation's healthcare infrastructure, this article will help you seize opportunities and meet challenges.

Biomedical Engineering↗

Bioengineering education, 1986--Part VII.

This paper concludes the Journal's series on Bioengineering Education in the United States. In this issue, college-level programs in the states of Alabama, Florida, Georgia, Louisiana, Mississippi, North Carolina, South Carolina, and Tennessee are described. These programs range from two-year bachelor degree, master's degree, doctoral degree, and M.D./Ph.D. combined programs. The intent of this paper is not to evaluate the various programs, but to illustrate the breadth of biomedical and related engineering educational opportunities in this region.

Biomedical Engineering↗

Age dependence of cellular properties of human septal cartilage: implications for tissue engineering.

BACKGROUND: The persistent need for cartilage replacement material in head and neck surgery has led to novel cell culture methods developed to engineer cartilage. Currently, there is no consensus on an optimal source of cells for these endeavors. OBJECTIVES: To evaluate human nasal cartilage as a potential source of chondrocytes and to determine the effect of donor age on cellular and proliferation characteristics. SUBJECTS: Nasal cartilage specimens were obtained after reconstructive surgery from 46 patients ranging in age from 15 to 60 years. METHODS: Specimens were weighed and chondrocytes were isolated by digestion in 0.2% collagenase type II for 16 hours. Cells were maintained in primary cultures until confluency, then seeded onto polylactic acid-polyglycolic acid scaffolds. Seeding efficiency was determined by quantification of DNA content of seeded constructs by means of Hoechst dye 33258. Specimen weights, cell yields, cell content, and doubling time were also measured and correlated to donor age. RESULTS: Mean (+/-SD) cartilage mass obtained (648 +/- 229 mg) is higher than from typical biopsy specimens of auricular cartilage, and the cellular characteristics show a higher proliferation rate than auricular chondrocytes. Cell yield increased with age, while doubling time decreased with age in samples from patients ranging from 15 to 60 years old. CONCLUSIONS: The use of nasal septal cartilage as a source of cells for tissue engineering may be valid over a wide range of patient ages. The large tissue yield and consequent cell yield make this tissue a potential starting source of chondrocytes for large-volume tissue-engineered implants.

Adolescent↗

The Personal Acoustics Lab (PAL): a microcomputer-based system for digital signal acquisition, analysis, and synthesis.

A new, integrated digital signal processing (DSP) system, the Personal Acoustics Lab (PAL), is described. This microcomputer-based system is suitable for analogue signal digitization at rates from several samples per hour to 150,000 samples per second in 12- or 16-bit words. Data may be acquired on one to sixteen single-ended A/D, or one to eight double-ended A/D channels in bipolar or unipolar modes. Digitized data may be reconverted to analogue signals using one or two D/A channels. An external clock and trigger and two bidirectional digital ports are provided. Integrated PAL-ILS software commands perform all necessary DSP functions, including: data editing, time- and frequency-domain graphical display, plotting, filtering, Fourier and Hilbert transforms, linear predictive coding, auto- and cross-correlation, and summary statistics. The system is suitable for biological and engineering DSP applications. Output from selected PAL-ILS software commands is illustrated using a bioacoustical example.

Animals↗

Web-based education in bioprocess engineering.

The combination of web technology, knowledge of bioprocess engineering, and theories on learning and instruction might yield innovative learning material for bioprocess engineering. In this article, an overview of the characteristics of web-based learning material is given, as well as guidelines for the design of learning material from theories of learning and instruction and from the bioprocess engineering domain. A diverse body of learning material is presented, which illustrates the application of these guidelines; this material has been developed during the past six years for different courses, mostly at undergraduate level, and it illustrates how web-based learning material can enable various different approaches to learning objectives that might improve overall learning. Such learning material has been used for several years in education, it has been evaluated with positive results, and is now part of the regular learning material for bioprocess engineering at Wageningen University.

Biomedical Engineering↗

Know-how and know-why in biochemical engineering.

This contribution analyzes the position of biochemical engineering in general and bioprocess engineering particularly in the force fields between fundamental science and applications, and between academia and industry. By using culture technology as an example, it can be shown that bioprocess engineering has moved slowly but steadily from an empirical art concerned with mainly know-how to a science elucidating the know-why of culture behavior. Highly powerful monitoring tools enable biochemical engineers to understand and explain quantitatively the activity of cellular culture on a metabolic basis. Among these monitoring tools are not just semi-online analyses of culture broth by HPLC, GC and FIA, but, increasingly, also noninvasive methods such as midrange IR, Raman and capacitance spectroscopy, as well as online calorimetry. The detailed and quantitative insight into the metabolome and the fluxome that bioprocess engineers are establishing offers an unprecedented opportunity for building bridges between molecular biology and engineering biosciences. Thus, one of the major tasks of biochemical engineering sciences is not developing new know-how for industrial applications, but elucidating the know-why in biochemical engineering by conducting research on the underlying scientific fundamentals.

Biochemistry↗

The current status of tissue engineering as potential therapy.

End-stage organ disease and tissue loss continue to be major medical problems. Although transplantation has become an established and successful method of therapy, the severe scarcity of donor organs, especially in the pediatric population, has become a major limitation and has stimulated investigation into selective cell transplantation. The authors have been investigating the fabrication of functional living tissue, or tissue engineering, using cells seeded on highly porous synthetic biodegradable polymer scaffolds as a novel approach toward the development of biological substitutes that may replace lost tissue function. Over the past decade, we have applied the principles of tissue engineering in the fabrication of a wide variety of tissues, including both structural and visceral organs. This article reviews the progress that has been achieved and the current status of tissue engineering as potential therapy for end-stage organ disease and tissue loss.

Biological Products↗

Aspects of human factors engineering in home telemedicine and telerehabilitation systems.

Human factors engineering and system design are critical elements in the newly developing field of telerehabilitation. Telerehabilitation is the remote delivery of rehabilitative services such as monitoring, training, and long-term care of persons with disabilities using telecommunications technology. This paper describes projects at the Rehabilitation Engineering Research Center (RERC) on Telerehabilitation in the context of three conceptual models: telecounseling and training, telemonitoring and assessment, and teletherapy. Issues pertaining to human factors engineering design are identified, and ongoing challenges are discussed.

Biomedical Engineering↗

Preadipocyte seeded PLGA scaffolds for adipose tissue engineering.

Adipose tissue equivalents have not been addressed as yet despite the clinical need in congenital deformities, posttraumatic repair, cancer rehabilitation, and other soft tissue defects. Preadipocytes were successfully harvested from rat epididymal fat pads of Sprague-Dawley and Lewis rats and expanded ex vivo. In vitro cultures demonstrated full differentiation of preadipocytes into mature adipocytes with normal lipogenic activity. The onset of differentiation was well-controlled by regulating preadipocyte confluency. Poly(lactic-co-glycolic) acid (PLGA) polymer disks with 90% porosity, 2.5 mm thick, 12 mm diameter, pore size range of 135-633 microm were fabricated and seeded with preadipocytes at 10(5) cells/mL. Disks in vitro demonstrated fully differentiated mature adipocytes within the pores of the disks. Short-term in vivo experiments were conducted by implanting preseeded disks subcutaneously on the flanks of rats for 2 and 5 weeks. Histologic staining of harvested disks with osmium tetroxide (OsO4) revealed the formation of adipose tissue throughout the disks. Fluorescence labeling of preadipocytes confirmed that formed adipose tissue originated from seeded preadipocytes rather than from possible infiltrating perivascular tissue. This study demonstrates the potential of using primary preadipocytes as a cell source in cell-seeded polymer scaffolds for tissue engineering applications.

Adipocytes↗

Metabolic flux analysis: a powerful tool for monitoring tissue function.

In recent years, metabolic flux analysis has been widely used in bioprocess engineering to monitor cell viability and improve strain activity. Metabolic flux analysis refers to a methodology for investigating cellular metabolism whereby intracellular fluxes are calculated using a stoichiometric model for the major intracellular reactions and applying mass balances around intracellular metabolites. A powerful feature of this methodology is its ability to consider cellular biochemistry in terms of reaction networks. By considering the stoichiometry of biochemical reactions, it is possible to estimate the degree of engagement of each pathway participating in overall cellular activity, and hence obtain a comprehensive view of a cell s metabolic state. Given the potential impact of cellular energy metabolism on the function of engineered tissues, such comprehensive analysis of metabolic activity can be an extremely useful tool for tissue engineers. Estimates of intracellular fluxes under various environmental conditions could be used to optimize function in vivo as well as culture conditions in vitro. In this review, we provide a brief theoretical background of metabolic flux analysis and summarize the most widely used experimental approaches to obtain flux data. This review is intended as an overview of the field and as a starting point for tissue engineers wishing to learn about and eventually employ this methodology.

Animals↗