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At least 919 records · Page 51Linked to original sources
PubMedDate not supplied

Evaluation of plasma resistant hollow fiber membranes for artificial lungs.

Hollow fiber membranes (HFMs) used in artificial lungs (oxygenators) undergo plasma leakage (or wetting) in which blood plasma slowly fills the pores of the fiber wall, plasma leaks into gas pathways, and overall gas exchange decreases. To overcome this problem plasma resistant fibers are being developed that are skinned asymmetric or composite symmetric versions of microporous oxygenator fibers. This report evaluates several candidate plasma resistant HFMs in terms of their gas permeance and plasma resistance as measured in a surfactant wet out test. Five candidate fibers were compared with each other and with a control fiber. CO2 and O2 gas permeance (in ml/s/cm2/cm Hg) in the plasma resistant fibers ranged from 3.15E-04 to 1.71E-03 and 3.40E-04 to 1.08E-03, respectively, compared with 1.62E-02 and 1.77E-02 for the control fiber. Maximum dye bleed through for the plasma resistant fibers in the forced wet out test were significantly less than for the control fiber. CO2 gas permeance of a plasma resistant fiber imposes the greatest constraint upon artificial lung design for sufficient gas exchange. However, our results suggest sufficient plasma resistance can be achieved using special skinned and composite HFMs while maintaining an acceptable CO2 gas permeance for a broad range of artificial lung applications.

Artificial Organs↗
PubMed1983

Experimental urinary bladder reconstruction using a synthetic poly(alpha-amino acids) membrane.

Biodegradability of the poly(epsilon-benzyloxycarbonyl-L-lysine) membrane was tested for use as a biodegradable graft for the reconstruction of rabbit urinary bladder. Rabbit urinary bladder was exposed through a midline incision under general anesthesia and segmental resection with full thickness was done, with replacement by this synthetic membrane. The membrane was gradually reabsorbed, serving as a framework of support for regeneration of normal bladder tissues. Follow-up study at 1 year revealed no urinary tract complications, such as bladder stones or urinary tract infection. Also, no disturbance of renal function was demonstrated. Bladder capacity remained within normal limits and bladder functions were almost normal. These results indicate that biodegradable membrane may be well suited to this clinical use.

Animals↗
PubMed1992

Artificial liver support based on artificial cells with emphasis on encapsulated hepatocytes.

Artificial liver support requires more than a detoxification system. We have investigated additional approaches. Microencapsulated hepatocytes increased the survival time of fulminant hepatic failure (FHF) rats. They also lowered the bilirubin in Gunn rats. Xenograft of microencapsulated rat hepatocytes into mice are immunoisolated. The viability of hepatocyte increased from 62 to 100% after 29 days. This is because of accumulation of a hepatic stimulatory factor (> 100,000 D) secreted by the hepatocytes in the artificial cells. A novel two-step method of cell encapsulation greatly improved immunoisolation and biocompatibility. Other metabolic approaches included a multienzyme system for conversion of ammonia to essential amino acid, and removal of bilirubin.

Animals↗
PubMed2000

[Progress in the field of tissue engineering].

Tissue engineering is a new field in biomedical engineering. In this review, progress in the field of tissue engineering is presented in detail, including a general introduction, design and fabrication principles, key technologies, various applications, new directions, as well as related market and R&D issues.

Animals↗
PubMed1990

Membranes as substrates for hepatocyte adhesion in liver support bioreactors.

Fourteen membranes out of cellulose (CuprophanR), polyamide and polypropylene were compared in a cytocompatibility test using the cytokinetics and cytomorphology of primary hepatatocytes as parameters. Additionally, the impact of coating the membranes with collagen or fibronectin was investigated. Hepatocytes were not able to attach in acceptable amounts on investigated cellulose membranes. On polyamide and polypropylene membranes a sufficient cell seeding was possible. Coating with collagen or fibronectin improves the attachment and spreading on all membranes. Differences between collagen and fibronectin were detected, observing the morphology of the cells: on collagen, most of the cells spread, whilst on fibronectin, most of the cells spread and flattened polygonally. If the adhesion of hepatocytes prolongs their metabolic function, a large adhesion surface in bioreactors is necessary. To reach a high surface area for cell adhesion in bioreactors one possibility is the use of polyamide and polypropylene membranes.

Animals↗
PubMed1978

[Diagnosis of vibriosis in bulls at breeding stations through lavages of the artificial vagina].

The objective of the study was to test the suitability of lavages of artificial vaginas which are used for collecting ejaculate for diagnosing the Campylobacter fetus subsp. fetus germs. According to the results of the investigation this method may be considered equal to the method of lavages of the prepuce. However, it is important to point out the advantages: it eliminates the danger of an accident, it enables quality lavage in the laboratory. To caputure the Campylobacter fetus the filtration through diaphragm filters is used together with the culture medium Fluid Thioglycollate medium (Difco) with an additive of agar, 10% ram blood and antibiotics (bacitracin, novobiocin). The catch rate in the prepuce lavages is 26.9%, in lavages of the artificial vagina 26.1%. The insignificant difference between the errors of the methods, i.e. the number of negative findings by employing one method and positive results with the other method, is 24.4% in lavages of the artificial vagina and 22.0% in lavages of the prepuce.

Animals↗
PubMed2003

Anesthetic management for the placement of a fully implantable artificial replacement heart: a case report.

Of the patients with end-stage cardiomyopathy on a heart transplant list, 95% do not receive a donor heart. Due to this severe shortage of donor organs, an artificial replacement heart has been pursued for several decades. To date, 10 patients have received an Abiocor artificial replacement heart (Abiomed, Inc, Danvers, Mass), the latest artificial heart device available. Anesthetic management often is complicated by the preoperative multisystem organ failure arising from the patient's advanced cardiomyopathy. Hemodynamic stabilization before cardiopulmonary bypass is extremely challenging, and the postbypass period creates a unique situation in which the only control the anesthesia provider has on the hemodynamics is management of the systemic vascular resistance. This article describes the anesthetic management of the recipient of the Abiocor artificial heart with the longest survival time.

Aged↗
PubMedDate not supplied

Solving the organ shortage: potential strategies and the likelihood of success.

The discrepancy between the demand and supply of organs for clinical transplantation remains a major problem. The current incidence of end-stage renal disease results in a patient population that doubles every decade. However, there have been no advancements in developing a comparable increase in the number of available allografts. There are three potential approaches to solving the shortage. In the near-term, the development of technology to access the pool of warm ischemically damaged organs may represent a solution. To achieve this goal, it will be necessary to develop technology that mimics the physiologic processes of wound repair. Alternatively, it has been proposed that an increased supply of organs can be developed with xenografts. To make xenotransplantation a clinical reality, it will be necessary to overcome the barriers that exist in nature between the species. Recent work in the area of stem cell research has provided evidence supporting the potential of generating biohybrid organs. A major undertaking of this emerging field will be to develop the ability to define and control the differentiation processes involved in organ specificity. The following is a review of the current status and relative issues involved with these three potential approaches to solving the organ shortage.

Animals↗
PubMedDate not supplied

Toward human organ printing: Charleston Bioprinting Symposium.

The First Annual Charleston Bioprinting Symposium was organized by the Bioprinting Research Center of the Medical University of South Carolina (MUSC) and convened July 21, 2006, in Charleston, South Carolina. In broad terms, bioprinting is the application of rapid prototyping technology to the biomedical field. More specifically, it is defined as the layer by layer deposition of biologically relevant material. The 2006 Symposium included four sessions: Computer-aided design and Bioprinting, Bioprinting Technologies; Hydrogel for Bioprinting and, finally, a special session devoted to ongoing research projects at the MUSC Bioprinting Research Center. The Symposium highlight was the presentation of the multidisciplinary Charleston Bioengineered Kidney Project. This symposium demonstrated that bioprinting or robotic biofabrication is one of the most exciting and fast-emerging branches in the tissue engineering field. Robotic biofabrication will eventually lead to industrial production of living human organs suitable for clinical transplantation. The symposium demonstrated that although there are still many technological challenges, organ printing is a rapidly evolving feasible technology.

Artificial Organs↗
PubMed2002

Tissue engineering and reparative medicine.

Reparative medicine is a critical frontier in biomedical and clinical research. The National Institutes of Health Bioengineering Consortium (BECON) convened a symposium titled "Reparative Medicine: Growing Tissues and Organs," which was held on June 25 and 26, 2001 in Bethesda, Maryland. The relevant realms of cells, molecular signaling, extracellular matrix, engineering design principles, vascular assembly, bioreactors, storage and translation, and host remodeling and the immune response that are essential to tissue engineering were discussed. This overview of the scientific program summarizes the plenary talks, extended poster presentations and breakout session reports with an emphasis on scientific and technical hurdles that must be overcome to achieve the promise of restoring, replacing, or enhancing tissue and organ function that tissue engineering offers.

Animals↗