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PubMedDate not supplied

Protecting the immunocompromised patient: the role of the hospital clinical engineer.

While the discipline of clinical engineering has long been limited to the area of medical equipment management, few areas in hospital engineering practice so closely meet the literal definition of "clinical" engineering as the care of the immunocompromised patient. Although ventilation has been the domain of the plant maintenance department, the increasing numbers of clinical engineers being given responsibility for plant functions, as well as the critical nature of the topic, make the care of the bone marrow transplant (BMT) patient an appropriate area of clinical engineering practice. Further, as clinical engineering branches out of the equipment management area, the clinical engineer can be truly termed the "hospital engineer".

Air Microbiology↗

PubMed1999

Lung function disturbances and chest X-ray abnormalities among marine engineers.

BACKGROUND: The purpose of the study was to investigate to what extent marine engineers who are exposed to mineral oil mist in the engine rooms of ships have lung function disturbances and chest X-ray abnormalities. METHODS: A previous study examined a cohort of 492 seamen from which we received 169 full-scale (40 x 40 cm) chest radiographs. Among these films were 68 from marine engineers and 101 from seamen who had never worked as engineers (controls). Spirometric data were obtained from 44 engineers and from 71 of the controls. The chest X-rays were classified independently by two certified B-readers, using the ILO classification. RESULTS: Only 7% of the seamen had parenchymal or pleural changes. The only statistically significant difference between the two groups for the chest X-ray findings was for all comments made by the ILO readers which were termed "any symbol" (9.3% for the engineers and 0.6% for the controls; RR = 14.6 (95% CI 1.1-75.5)) and the FEV% (FEV1/FVC x 100) for the spirometric values (82.8 (SD = 10.8) for the engineers and 86.6 (SD = 8.0) for the controls; P = 0.03). CONCLUSIONS: The results of the study indicate a slight lung function impairment and an increase in chest X-ray abnormalities, other than small opacities, among the marine engineers.

Adult↗

PubMed2001

Dynamics of extracellular matrix production and turnover in tissue engineered cardiovascular structures.

Appropriate matrix formation, turnover and remodeling in tissue-engineered small diameter vascular conduits are crucial requirements for their long-term patency and function. This complex process requires the deposition and accumulation of extracellular matrix molecules as well as the remodeling of this extracellular matrix (ECM) by matrix metalloproteinases (MMPs) and their endogenous inhibitors (TIMPs). In this study, we have investigated the dynamics of ECM production and the activity of MMPs and TIMPs in long-term tissue-engineered vascular conduits using quantitative ECM analysis, substrate gel electrophoresis, radiometric enzyme assays and Western blot analyses. Over a time period of 169 days in vivo, levels of elastin and proteoglycans/glycosaminoglycans in tissue-engineered constructs came to approximate those of their native tissue counter parts. The kinetics of collagen deposition and remodeling, however, apparently require a much longer time period. Through the use of substrate gel electrophoresis, proteolytic bands whose molecular weight was consistent with their identification as the active form of MMP-2 (approximately 64--66 kDa) were detected in all native and tissue-engineered samples. Additional proteolytic bands migrating at approximately 72 kDa representing the latent form of MMP-2 were detected in tissue-engineered samples at time points from 5 throughout 55 days. Radiometric assays of MMP-1 activity demonstrated no significant differences between the native and tissue-engineered samples. This study determines the dynamics of ECM production and turnover in a long-term tissue-engineered vascular tissue and highlights the importance of ECM remodeling in the development of successful tissue-engineered vascular structures.

Animals↗

PubMed2003

Cardiac tissue engineering for replacement therapy.

Cell therapy is a new concept to repair diseased organs. For patients with myocardial infarction, heart failure, and congenital heart diseases cell based therapies might represent a potential cure. The field can be subdivided into two principally different approaches: (1) Implantation of isolated cells and (2) implantation of in vitro engineered tissue constructs. This review will focus on the latter approach. Cardiac tissue engineering comprises the fields of material sciences and cell biology. In general, scaffold materials such as gelatin, collagen, alginate, or synthetic polymers and cardiac cells are utilized to reconstitute tissue-like constructs in vitro. Ideally, these constructs display properties of native myocardium such as coherent contractions, low diastolic tension, and syncytial propagation of action potentials. To be applicable for surgical repair of diseased myocardium engineered tissue constructs should have the propensity to integrate and remain contractile in vivo. Size and mechanical properties of engineered constructs are critical for surgical repair of large tissue defects. Successful application of tissue engineering in men will depend on the utilization of an autologous or non-immunogeneic cell source and scaffold material to avoid life long immunosuppression. This review will give an overview of recent approaches in cardiac tissue engineering and its first applications in vivo. We will discuss materials and cell sources for cardiac tissue engineering. Further, principle obstacles will be addressed. Cardiac tissue engineering for replacement therapy has an intriguing perspective, but is in its early days. Its true value remains to be thoroughly evaluated.

Animals↗

PubMed2001

Bronchial mucosa produced by tissue engineering: a new tool to study cellular interactions in asthma.

BACKGROUND: The use of fiberoptic bronchial biopsies has improved our understanding of the immunopathology of asthma. However, this approach offers a limited ability to perform mechanistic studies observing cell-cell and cell-matrix interactions, which are a key issue in the study of airway remodeling. Tissue engineering is a technique that combines the use of biology and engineering expertise to generate a limitless amount of tissue from small samples. This technology allows for the study of cell interactions under conditions as close as possible to the natural environment. OBJECTIVE: The aim of this study was to evaluate the feasibility of an engineered human bronchial mucosa as a model to study cellular interactions in asthma. METHODS: Human bronchial fibroblasts from normal and asthmatic donors were incorporated into collagen gel. Bronchial epithelial cells were seeded over this gel and then cultured in an air-liquid interface in the presence or the absence of T lymphocytes. Biopsy specimens from these engineered mucosa were taken for structural and ultrastructural analysis, and T lymphocytes were harvested and used to localize IL-5. RESULTS: Histologic analysis showed that engineered mucosa with normal bronchial cells presented a pseudostratified ciliated epithelium with the presence of mucus secretory cells. The electron microscopy analysis confirmed these histologic results. These features were comparable with those observed in normal bronchial tissues. However, in engineered mucosa from asthmatic subjects, the tissue structure was disorganized, particularly the epithelial cell arrangement. The percentage of IL-5(+) lymphocytes was significantly (P =.03) higher in engineered bronchial mucosa from asthmatic subjects (87% +/- 2%) compared with mucosa from normal volunteers (2% +/- 0.3%). CONCLUSION: Using tissue engineering, we produced an in vitro model of bronchial mucosa from normal and asthmatic subjects. These models could be a valuable tool to better understand key mechanisms involved in inflammation and airway repair.

Asthma↗

PubMed1995

Hydrophobicity engineering to increase solubility and stability of a recombinant protein from respiratory syncytial virus.

Site-directed mutagenesis has been employed to engineer the hydrophobic properties of a 101-amino-acid fragment from the human respiratory syncytial virus (RSV) major glycoprotein (G protein). When this protein was produced in Escherichia coli, more than 70% of the gene product was found as inclusion bodies, and the product recovered from the soluble fraction was severely degraded. Substitution of two cysteine residues for serine residues, did not significantly change the solubility or stability of the gene product. In contrast, a dramatic increase in both solubility and stability was achieved by multiple engineering of hydrophobic phenylalanine residues. As compared to the non-engineered protein, the fraction of soluble protein in vivo could be increased from 27% to 75%. Surprisingly, this effect was accompanied by a remarkable increase in stability. The in vitro solubility of the purified gene products was similarly increased approximately fivefold. Structural studies using circular dichroism suggest that the two engineered fragments have a distribution of secondary-structure elements similar to the non-engineered fragment. In addition, the two engineered G-protein variants were demonstrated to be at least in part antigenically authentic to the non-engineered gene product. These results demonstrate that engineering of hydrophobic residues can be used as a tool to increase the solubility and proteolytic stability of poorly soluble and labile proteins.

Amino Acid Sequence↗

PubMed2000

Functional tissue engineering: the role of biomechanics.

"Tissue engineering" uses implanted cells, scaffolds, DNA, protein, and/or protein fragments to replace or repair injured or diseased tissues and organs. Despite its early success, tissue engineers have faced challenges in repairing or replacing tissues that serve a predominantly biomechanical function. An evolving discipline called "functional tissue engineering" (FTE) seeks to address these challenges. In this paper, the authors present principles of functional tissue engineering that should be addressed when engineering repairs and replacements for load-bearing structures. First, in vivo stress/strain histories need to be measured for a variety of activities. These in vivo data provide mechanical thresholds that tissue repairs/replacements will likely encounter after surgery. Second, the mechanical properties of the native tissues must be established for subfailure and failure conditions. These "baseline data" provide parameters within the expected thresholds for different in vivo activities and beyond these levels if safety factors are to be incorporated. Third, a subset of these mechanical properties must be selected and prioritized. This subset is important, given that the mechanical properties of the designs are not expected to completely duplicate the properties of the native tissues. Fourth, standards must be set when evaluating the repairs/replacements after surgery so as to determine, "how good is good enough?" Some aspects of the repair outcome may be inferior, but other mechanical characteristics of the repairs and replacements might be suitable. New and improved methods must also be developed for assessing the function of engineered tissues. Fifth, the effects of physical factors on cellular activity must be determined in engineered tissues. Knowing these signals may shorten the iterations required to replace a tissue successfully and direct cellular activity and phenotype toward a desired end goal. Finally, to effect a better repair outcome, cell-matrix implants may benefit from being mechanically stimulated using in vitro "bioreactors" prior to implantation. Increasing evidence suggests that mechanical stress, as well as other physical factors, may significantly increase the biosynthetic activity of cells in bioartificial matrices. Incorporating each of these principles of functional tissue engineering should result in safer and more efficacious repairs and replacements for the surgeon and patient.

Biocompatible Materials↗

PubMed1993

Survival and impact of genetically engineered Pseudomonas putida harboring mercury resistance gene in aquatic microcosms.

The survival of wild-type and genetically engineered Pseudomonas putida PpY101 that contained a recombinant plasmid pSR134 conferring mercury resistance were monitored in aquatic microcosms. We used lake, river, and spring water samples. The density of genetically engineered and wild-type P. putida decreased rapidly within 5 days (population change rate k -0.87 approximately -1.00 day-1), then moderately after 5 to 28 days (-0.10 approximately -0.14 day-1). The population change rates of genetically engineered and wild-type P. putida were not significantly different. We studied the important factors affecting the survival of genetically engineered and wild-type P. putida introduced in aquatic microcosms. Visible light exerted an adverse effect on the survival of the two strains. The densities of genetically engineered and wild-type P. putida were almost constant until 7 days after inoculation in natural water filtered with a 0.45-micron membrane filter, or treated with cycloheximide to inhibit the growth of protozoa. These results suggested that protozoan predation was one of the most important factors for the survival of two strains. We examined the impact of the addition of genetically engineered and wild-type P. putida on indigenous bacteria and protozoa. Inoculation of genetically engineered or wild-type P. putida had no apparent effect on the density of indigenous bacteria. The density of protozoa increased in microcosms inoculated with genetically engineered or wild-type P. putida at 3 days after inoculation, but after 5 to 21 days, the density of protozoa decreased to the same level as the control microcosms.

Animals↗

PubMed1997

Novel insulinoma cell lines produced by iterative engineering of GLUT2, glucokinase, and human insulin expression.

Cellular engineering studies in our group are directed at creating insulin-secreting cell lines that simulate the performance of the normal islet beta-cell. The strategy described in this article involves the stepwise stable introduction of genes relevant to beta-cell performance into the RIN 1046-38 insulinoma cell line, a process that we term "iterative engineering." RIN cells stably engineered to contain multiple copies of the human insulin gene exhibit a large increase in insulin content, such that they approach the content of human islets assayed in parallel. Analysis by high-performance liquid chromatography demonstrates that these engineered cell lines process human proinsulin to mature insulin with high efficiency. Cell lines that are further engineered to express the GLUT2 and glucokinase genes demonstrate stable expression of the three transgenes for the full lifetime of the lines produced to date (6 months to 1 year in continuous culture). Transplantation of the engineered cell lines into nude rats reveals that stably integrated genes are expressed at constant levels in the in vivo environment over the full duration of experiments performed (48 days). Several endogenous genes expressed in normal beta-cells, including rat insulin, amylin, sulfonylurea receptor, and glucokinase, are stably expressed in the insulinoma lines during these in vivo studies. Endogenous GLUT2 expression, in contrast, is rapidly extinguished during in vivo passage. The loss of GLUT2 is overcome in engineered cell ines in which transporter expression is provided by a stably transfected transgene. These results suggest that a potential advantage of the iterative engineering approach may be to preserve stability of function and phenotype, particularly in the in vivo setting.

Animals↗

PubMed2026

Simplifying multiplex genome engineering in Saccharomyces cerevisiae with intron-mediated Random Assembly and INtegration (RAIN).

Engineering of multistep enzymatic pathways often involves extensive optimization of heterologous gene expression levels and requires cloning of promoter and open reading frames (ORFs) to generate expression cassettes. We present work on a nascent method for multiplex genome engineering in Saccharomyces cerevisiae that negates the requirement for cloning of expression cassettes. Our system, Random Assembly and INtegration (RAIN), uses intron-mediated homologous recombination (HR) for random in vivo assembly of exogenous promoter and ORF libraries, which are combined and cotransformed in a one-pot method. The libraries include consensus homology arms which target long terminal repeat regions of the Ty1 retrotransposon, providing over a hundred possible integration loci. In this way, our developmental system aims to negate the need for in vitro combinatorial cloning of promoters and ORFs to generate expression cassettes, simplifying in vitro DNA preparation before multiplex genome engineering. This paper presents findings from a series of experiments to demonstrate a proof of concept for the RAIN system. These include: the first reported use of intron-mediated assembly of promoters and ORFs for expression of a functional gene product; up to three markerless genomic integrations; and up to five integrations with antibiotic selection. We also present a number of innovations to improve integration efficiency during multiplex engineering in S. cerevisiae including: SGS1 gene knockout; disruption of heteroduplex rejection; modified Cas9 expression architecture; and overexpression of HR genes RAD52, MRE11, and RAD59. To demonstrate how our system can be used for single transformation phenotype engineering of multiple strains, we also transformed a library of methylotrophy associated genes to generate four new strains that were able to grow on a solid minimal medium with methanol as the sole additional carbon source. Our findings contribute to the ongoing efforts to improve multiplex genome engineering tools in S. cerevisiae, and provide the foundations for further development of a novel toolbox for generating useful genetic diversity for metabolic pathway engineering.

Saccharomyces cerevisiae↗

PubMed1989

32P-postlabelling analysis of DNA adducts in the skin of mice treated with petrol and diesel engine lubricating oils and exhaust condensates.

Samples of unused or used petrol and diesel engine lubricating oils were applied to the shaved dorsal skin of 4- to 6-week-old male Parkes mice, either as a single treatment (50 microliters/mouse) or as four consecutive daily treatments (50 microliters/application). DNA isolated from the skin 24 h after the final treatment was digested to 3'-mononucleotides and analysed by 32P-postlabelling for the presence of aromatic adducts. Enhancement of sensitivity using butanol extraction or nuclease P1 digestion of the DNA hydrolysates led to the detection of up to eight adduct spots on polyethyleneimine-cellulose thin-layer chromatograms with samples of DNA from skin treated with used engine oils, at levels of 40-150 amol total adducts/micrograms DNA. Multiple treatments with the used oils gave rise to similar patterns of adducts in lung DNA. A single treatment of mouse skin with petrol engine exhaust condensate (50 microliters), or diesel engine exhaust condensate (50 microliters), containing 20 and 46 micrograms benzo[a]pyrene (BaP)/g respectively, gave rise to approximately 75 amol total adducts/micrograms DNA in skin. A significant proportion, 31 and 48% respectively, of the adducts formed by the petrol and diesel engine exhaust condensates co-chromatographed with the major BaP-DNA adduct, but with the used engine oils, only petrol engine oil, and not diesel engine oil, produced significant amounts of an adduct (22% of total) that corresponded to the BaP-DNA adduct.

Adenosine Triphosphate↗

PubMed2000

Long-term follow-up of tissue-engineered intestine after anastomosis to native small bowel.

BACKGROUND: Our laboratory has investigated the fabrication of a tissue-engineered intestine using biodegradable polymer scaffolds. Previously we reported that isolated intestinal epithelial organoid units on biodegradable polymer scaffolds formed cysts and the neointestine was successfully anastomosed to the native small bowel. The purpose of this study was to observe the development of tissue-engineered intestine after anastomosis and to demonstrate the effect of the anastomosis over a 9-month period. METHODS: Microporous biodegradable polymer tubes were created from polyglycolic acid. Intestinal epithelial organoid units were harvested from neonatal Lewis rats and seeded onto the polymers, which were implanted into the abdominal cavity of adult male Lewis rats followed by 75% small bowel resection (n=24). Three weeks after implantation, the unit/polymer constructs were anastomosed to the native jejunum in a side-to-side fashion. The anastomosed tissue-engineered intestine was measured by laparotomy 10, 24, and 36 weeks after the implantation (n= 14). During the laparotomy, all rats with an obstruction in their anastomosis were killed and excluded from the statistical analysis. Another five rats were also killed at 10 and 36 weeks for histological and morphometric studies. RESULTS: All analyzed rats survived this study and significantly increased their body weight by 36 weeks. Obstruction of the anastomosis was observed in one rat at 24 weeks and in two rats at 36 weeks; however, the anastomosis was patent in the other 11 rats by 36 weeks. The tissue-engineered intestine of these 11 rats increased in length and diameter at 10, 24, and 36 weeks after anastomosis; there were statistically significant differences between each time point except between the length of 10 and 24 weeks (P<0.016 by Wilcoxon signed rank test). Histologically the inner surface of the tissue-engineered intestine was lined with well-developed neomucosa at 10 and 36 weeks; however, there were small bare areas lacking neomucosa in the tissue-engineered intestine at 36 weeks. Morphometric analysis demonstrated no significant differences in villus number, villus height, and surface length of the neomucosa at 10 and 36 weeks. CONCLUSIONS: Anastomosis between tissue-engineered intestine and native small bowel resulted in no complications after operation and maintained a high patency rate for up to 36 weeks. The tissue-engineered intestine increased in size and was lined with well-developed neomucosa for the duration of the study.

Anastomosis, Surgical↗

PubMed1997

Skin disorders in ship's engineers exposed to oils and solvents.

Ship's engineers are exposed to mineral oil and solvents in their work. This study was intended to investigate if the ship's engineers had an increased prevalence of skin disorders and whether any such increased risk could be linked to exposure to mineral oils and solvents. A self-administered questionnaire was sent to 700 male seamen from 3 Norwegian ferry countries. Of the 492 respondents, 169 were currently working as ship's engineers and 295 had never worked as ship's engineers. The outcomes eczema, acne, dry skin, and dermatitis and hand dermatitis were defined from the questionnaire. Prevalences of these skin disorders were compared between the groups. Logistic regression was used to elucidate explanatory variables further. When comparing current ship's engineers with those who had never worked as ship's engineers, the crude prevalence ratios were 1.7 (95% CI 1.1-2.7) for dry skin, 1.7 (95% CI 1.1-2.5) for any dermatitis, 1.3 (95% CI 0.66-2.67) for acne and 1.2 (CI 0.61-2.27) for eczema. The risk of these symptoms increased for the engineers in the regression analysis, after controlling for age, self-reported use of Stoddard solvent, and the use of fuel oil as hand cleansing agent. The increased prevalence of skin disorders found among ship's engineers in this investigation may be explained by direct contact with mineral oils and solvents.

Adult↗

PubMed2003

[Tissue engineering in urology. Basic principles and application].

Tissue engineering is a rather new field of science. Despite this fact, some experimental investigations have already been applied in clinical studies. Compared to other medical fields, tissue engineering in urology is well established. Tissue-engineered bulking agents and tissue-engineered bladder augments are being investigated in clinical trials. Even though the knowledge gained in recent years is promising, the results of cellular therapies need to be critically judged before being finally applied in patients. Genetic engineering and stem cell research (adult undifferentiated cells) have had major impact on the field of tissue engineering over the past 2 years. By using the technology of genetic engineering, biochemical and functional qualities of tissues may be modified. Adult stem cells may help to substitute lost tissue in an autologous fashion by isolating undifferentiated cells from the body and by differentiating them into a desired cell type. These cells may be used to form native functional tissue to replace a diseased organ or organ part.

Adult↗

PubMedDate not supplied

Presentation of the clinical engineering role to hospital administrators.

This paper constitutes a presentation to health care managers on the clinical engineering role in the hospital. Guidelines are covered that were issued in 1976, by the Joint Commission for the Accreditation of Hospitals: the engineering problems, goals, and solutions addressed in the clinical engineering function; the education of the clinical engineer; and the alternative methods of delivering engineering support services to the hospital. The material included in this paper can form the basis for presentations intended to increase awareness of the role of clinical engineering, improve compliance with JCAH requirements, and to stimulate action to make effective use of engineering.

Accreditation↗

PubMed1999

Metabolic engineering.

Metabolic engineering is the science that combines systematic analysis of metabolic and other pathways with molecular biological techniques to improve cellular properties by designing and implementing rational genetic modifications. As such, metabolic engineering deals with the measurement of metabolic fluxes and elucidation of their control as determinants of metabolic function and cell physiology. A novel aspect of metabolic engineering is that it departs from the traditional reductionist paradigm of cellular metabolism, taking instead a holistic view. In this sense, metabolic engineering is well suited as a framework for the analysis of genome-wide differential gene expression data, in combination with data on protein content and in vivo metabolic fluxes. The insights of the integrated view of metabolism generated by metabolic engineering will have profound implications in biotechnological applications, as well as in devising rational strategies for target selection for screening candidate drugs or designing gene therapies. In this article we review basic concepts of metabolic engineering and provide examples of applications in the production of primary and secondary metabolites, improving cellular properties, and biomedical engineering.

Biomedical Engineering↗

PubMed1997

Exposure to mineral oil mist and respiratory symptoms in marine engineers.

The purpose of the study was to see if marine engineers have an increased prevalence of respiratory symptoms, and if so whether it can be related to occupational exposures. A self-administered questionnaire was sent to 700 male seamen from three Norwegian ferry companies. Of the 492 respondents, 169 were currently working as marine engineers and 295 had never worked as marine engineers. The outcomes of cough and wheezing, chronic bronchitis, severe dyspnea, any dyspnea, and mucous membrane irritation (MMI) were defined from the questionnaire. Age and smoking-adjusted prevalences of these respiratory conditions were compared between the groups. Logistic regression was used to further elucidate the explanatory variables. The exposure assessment indicated an exposure (TWAC) to oil mist for marine engineers in the range from 0.12 to 0.74 mg/m3 (mean 0.45 mg/m3) When comparing current marine engineers with those who had never worked as marine engineers, the prevalence ratios were 1.38 (95% CI 1.0-1.9) for MMI, 1.53 (95% CI 1.2-1.9) for any dyspnea, and 1.63 (95% CI 1.0-2.6) for severe dyspnea. The differences remained for some of the symptoms after controlling for self-reported former asbestos exposure in the regression analysis. The increased prevalence of respiratory symptoms found among marine engineers in this investigation may partly be explained be oil-mist exposure, or more probably by a combination of past asbestos exposure and past and present oil-mist exposure.

Cross-Sectional Studies↗

PubMed2001

Tissue engineering in plastic reconstructive surgery.

Tissue engineering (TE) is a new interdisciplinary field of applied research combining engineering and biosciences together with clinical application, mainly in surgical specialities, to develop living substitutes for tissues and organs. Tissue engineering approaches can be categorized into substitutive approaches, where the aim is the ex vivo construction of a living tissue or organ similar to a transplant, vs. histioconductive or histioinductive concepts in vivo. The main successful approaches in developing tissue substitutes to date have been progresses in the understanding of cell-cell interactions, the selection of appropriate matrices (cell-matrix interaction) and chemical signalling (cytokines, growth factors) for stimulation of cell proliferation and migration within a tissue-engineered construct. So far virtually all mammalian cells can be cultured under specific culture conditions and in tissue specific matrices. Future progress in cell biology may permit the use of pluripotent stem cells for TE. The blueprint for tissue differentiation is the genome: for this it is reasonable to combine tissue engineering with gene therapy. The key to the progress of tissue engineering is an understanding between basic scientists, biochemical engineers, clinicians, and industry.

Animals↗