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At least 991 records · Page 55Linked to original sources
PubMed2002

Fabricating autologous tissue to engineer artificial nerve.

This study reports on the successful fabrication of artificial nerves with tissue engineering methods. Schwann cells were cultured for 2 weeks, seeded on polyglactin 910 scaffolds, and biomembrane-coated with rat-tail glue and laminin. Observation of the scaffolds' adsorptivity to Schwann cells, and of the growth and migration of Schwann cells, was made using a light microscope, and by scanning and transmission electron microscopy. The Schwann cells were able to migrate and proliferate on the polyglactin 910 fiber. Schwann cells were well-distributed, and formed a Büngner band on which the Schwann cells produced more matrices. Schwann cells on the biomembrane also grew well. We investigated the role of the tissue engineering conduit guide in vivo, using an established rabbit peripheral nerve regeneration model. At 8 weeks, axonal regeneration was observed in the distal nerve stump. Adult Schwann cells can be produced on the coated fiber and the biomembrane. Three-dimensional scaffolds with Schwann cells had the basic characteristics of the artificial nerve. These findings will provide a practical method for fabricating tissue-engineered artificial nerve to repair long nerve defects.

Animals↗
PubMed1999

Transfer of porcine endogenous retrovirus across hollow fiber membranes: significance to a bioartificial liver.

BACKGROUND: A porcine endogenous retrovirus (PERV) capable of infecting human cells has been identified. This study was designed to determine whether hollow fiber membranes, such as those used in a bioartificial liver, block the transfer of PERV. METHODS: Three hollow fiber cartridges (HFCs) were studied in duplicate: cellulose fibers with 70 kD nominal molecular weight cut-off (MWCO), polysulfone fibers with 400 kD MWCO, and mixed cellulose fibers with 200 nm porosity. PK15 cells (porcine kidney cell line), known to produce PERV, were grown in the intraluminal compartment of HFCs fiber cartridges. Samples of medium were collected from both intraluminal and extraluminal compartments of the HFCs fiber cartridge during 14 days of culture. Samples were screened for PERV using reverse transcription polymerase chain reaction. All positive samples were tested for PERV infectivity in human 293 cells. RESULTS: PERV was detected in all samples from the intraluminal space and all intraluminal samples seemed to infect 293 cells. All extraluminal samples from the fibers of 200 nm porosity tested positive for PERV. Detection of PERV in the extraluminal space was delayed by fibers of 400 kD MWCO and 70 kD MWCO until at least day 3 and day 7, respectively, after inoculation of PK15 cells. Positive extraluminal samples from fibers of 400 kD MWCO and 70 kD MWCO did not infect 293 cells. CONCLUSION: Pore size, membrane composition, and duration of exposure influenced the transfer of PERV across HFCs. Some HFCs decrease the risk of viral exposure to patients during bioartificial liver therapy.

Animals↗
PubMed1982

Coating membranes for a sorbent-based artificial liver: adsorption characteristics.

Techniques are described for the coating of sorbents to be used in an artificial liver support system based on mixed sorbent bed hemoperfusion. Activated charcoal has been coated with cellulose acetate (CA) by solvent evaporation. With Amberlite XAD-4, the Wurster technique was used for coating with CA. XAD-4 has also been coated with a synthetic polyelectrolyte with anticoagulant activity by adsorption and fixation by gamma radiation-induced crosslinking. Activated charcoal, XAD-4, and a cation exchange resin, all in powdered form, were encapsulated in agarose gel beads. Adsorption characteristics onto the sorbents are described. The results are in agreement with a theoretical model presented. In general, adsorption onto XAD-4 is limited by film diffusion. With activated charcoal, pore diffusion limitation is generally observed. Blood compatibility is improved by coating.

Absorption↗
PubMed1996

Organ-specific therapy in critical illness: interfacing molecular mechanisms with physiological interventions.

Sepsis and SIRS is the outward manifestation of a generalized uncontrolled inflammatory response, which, if sustained, induces widespread endothelial damage and MODS. Immunomodulating therapies, at present, have proven ineffective in reducing morbidity and mortality, presumably because of the heterogeneous nature of sepsis and septic shock and the reciprocating and redundant nature of this inflammatory cascade. Organ-specific therapies can support life but impair both organ-specific function and remote organ function. Novel therapies aimed at minimizing further organ dysfunction may improve outcome in a cost-effective fashion by preventing both further primary organ dysfunction or remote organ dysfunction secondary to the subsequent activation of the inflammatory response.

Animals↗
PubMed2004

Computer-aided tissue engineering: overview, scope and challenges.

Advances in computer-aided technology and its application with biology, engineering and information science to tissue engineering have evolved a new field of computer-aided tissue engineering (CATE). This emerging field encompasses computer-aided design (CAD), image processing, manufacturing and solid free-form fabrication (SFF) for modelling, designing, simulation and manufacturing of biological tissue and organ substitutes. The present Review describes some salient advances in this field, particularly in computer-aided tissue modeling, computer-aided tissue informatics and computer-aided tissue scaffold design and fabrication. Methodologies of development of CATE modelling from high-resolution non-invasive imaging and image-based three-dimensional reconstruction, and various reconstructive techniques for CAD-based tissue modelling generation will be described. The latest development in SFF to tissue engineering and a framework of bio-blueprint modelling for three-dimensional cell and organ printing will also be introduced.

Animals↗
PubMed2004

[Prevalence of hemorrhagic fever with renal syndrome virus in domestic pigs: an epidemiological investigation in Shandong province].

OBJECTIVE: To investigate the epidemiological significance of hemorrhagic fever with renal syndrome virus (HFRSV) infection in domestic pigs in Shandong province, and study the role of domestic pigs in the prevalence of HFRS. METHODS: Epidemiological investigation was performed in 4 cities of Shandong province. Reversed passive hemagglutination assay (RPHA), reversed passive hemagglutination inhibition (RPHI), HPR-SPA, immunofluorescent antibody (IFA), and reverse transcriptional PCR (RT-PCR) were used to detect antigen and antibody of HFRSV. RESULTS: HFRSV antigen and antibody were detected in the heart, liver, lung, spleen, kidney, blood, urine, and stool of domestic pigs as well as in the sewage of the pigpen facilities. The positivity rate of HFRSV antigen ranged from 3.33% to 5.00% in the organ of pigs, and HFRSV positivity rate in the blood, urine, stool, and sewage was 3.67%, 7.04%, 2.51%, and 5.56%, respectively, with a total serum antibody positivity rate of 1.96%. The virus was isolated from the HFRSV antigen-positive samples, and could infect many organs after artificial infection of the pigs. HFRSV antigen can be detected in suckling rat brain and histopathological examination suggested transient pathological changes in such organs as the liver, lung and kidney. HFRSV may proliferate in pigs and was discharged through multiple routes. CONCLUSION: Domestic pigs can be the host of HFRSV for the viral transmission.

Animals↗
PubMed1982

Derivation of transplantable 7,12-dimethylbenz[a]anthracene-induced chicken fibrosarcoma lines: differences in metastasizing properties and organ specificity.

Several transplantable 7,12-dimethylbenz[a]anthracene-induced SC chicken fibrosarcoma (CHCT-NYU) lines were studied for their ability to grow in internal organs after iv injection (artificial metastases) into 1- to 3-week-old chickens. Some tumor lines were recently derived, whereas others were studied after many serial subcutaneous transplantations. STriking similarities as well as differences were found between tumor lines' ability to grow in various organs. Artificial metastases were seen primarily in the stomach, pancreas, lungs, heart, and muscle, and occasionally also in the kidneys and in the liver. Agammaglobulinemic recipients showed more extensive organ involvement than normal recipients of the same age. Whole-body gamma-irradation also enhanced the incidence of artificial metastases, particularly in lungs. Antibody from the serum of a primary tumor-bearing host reduced the growth of the corresponding tumor in many organs. The metastatic pattern of line CHCT-NYU4 was a relatively stable property, since there was little difference in the internal localization of these tumor cells studied before and after 15 serial subcutaneous transplants. However, intravenous transplantation of tumor cells from line CHCT-NYU4 taken from the liver, lungs, and pancreas of a single recipient established sublines with changes in organ specificity. After a few such serial transplants of liver-derived tumor, a line was derived that grew virtually in the liver alone. A subline with preference for growth in lungs was also obtained, but its ability to grow in the pancreas persisted. A pancreas-derived tumor line also grew in the liver and lungs. Subcutaneous transplants of tissue fragments of the lung-derived tumor line caused the appearance of spontaneous metastases in lungs. The incidence of spontaneous metastases with the lung-derived line was much greater than that with the liver-derived line or with the original CHCT-NYU4 line.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2003

Cell and organ printing 2: fusion of cell aggregates in three-dimensional gels.

We recently developed a cell printer (Wilson and Boland, 2003) that enables us to place cells in positions that mimic their respective positions in organs. However, this technology was limited to the printing of two-dimensional (2D) tissue constructs. Here we describe the use of thermosensitive gels to generate sequential layers for cell printing. The ability to drop cells on previously printed successive layers provides a real opportunity for the realization of three-dimensional (3D) organ printing. Organ printing will allow us to print complex 3D organs with computer-controlled, exact placing of different cell types, by a process that can be completed in several minutes. To demonstrate the feasibility of this novel technology, we showed that cell aggregates can be placed in the sequential layers of 3D gels close enough for fusion to occur. We estimated the optimum minimal thickness of the gel that can be reproducibly generated by dropping the liquid at room temperature onto a heated substrate. Then we generated cell aggregates with the corresponding (to the minimal thickness of the gel) size to ensure a direct contact between printed cell aggregates during sequential printing cycles. Finally, we demonstrated that these closely-placed cell aggregates could fuse in two types of thermosensitive 3D gels. Taken together, these data strongly support the feasibility of the proposed novel organ-printing technology.

Animals↗
PubMed2002

The paracorporeal artificial lung improves 5-day outcomes from lethal smoke/burn-induced acute respiratory distress syndrome in sheep.

BACKGROUND: Our low-impedence, paracorporeal artificial lung (PAL) prototype is well-tolerated in-series with the normal sheep pulmonary circulation. Using our lethal dose 80% to 100% smoke/burn acute respiratory distress syndrome (ARDS) sheep model, we compared PAL to volume-controlled mechanical ventilation (VCMV) in a prospective, randomized, controlled, unblinded, 5-day outcome study. METHODS: Fourteen sheep were randomized to PAL (n = 8) versus VCMV (n = 6) to assess outcome. For PAL, arterial cannulas were anastomosed to the proximal and distal main pulmonary artery with an interposing snare diverting full flow through a paracorporeal loop. Acute respiratory distress syndrome was induced in both groups (48 breaths smoke insufflation, third degree burn on 40% of total body surface area). When acute respiratory distress syndrome criteria were met (24 to 30 hours after injury), the PAL was interposed in the paracorporeal loop. Both groups were managed with a VCMV algorithm minimizing tidal volume, ventilator rate, and fractional inspired concentration of oxygen (FiO2). RESULTS: Six of eight PAL versus 1 of 6 VCMV sheep survived the 5-day study. In PAL, cardiac output, mean arterial pressure, pulmonary artery pressure, left atrial pressure, and central venous pressure remained stable. Average PAL gas transfer was 218.6 +/- 17.7 mL/min O2 and 183.0 +/- 27.8 mL/min CO2. Ventilator settings 48 hours after lung injury in PAL were significantly lower (p < 0.05) than VCMV (TV 210 versus 425 mL; respiratory rate 6 versus 29 breaths/min; minute ventilation 1.2 versus 10.8 L/min; FiO2 21 versus 100%). Likewise, PaO2/FiO2 ratio was normalized in PAL and still met acute respiratory distress syndrome criteria in VCMV. The PAL wet/dry ratio was significantly lower than VCMV (6.36 +/- 0.63 versus 11.85 +/- 1.54; p = 0.008). CONCLUSIONS: In a prospective, randomized, controlled, unblinded, outcomes study, PAL decreased ventilator-induced lung injury in a lethal dose 80% to 100% ARDS model to improve 5-day survival.

Animals↗
PubMed1967

Spare-part surgery.

Explore the source record for details and available documents.

Artificial Limbs↗
PubMed2001

Two-dimensional finite element model for oxygen transfer in cross-flow hollow fiber membrane artificial lungs.

A predictive, two-dimensional model with good absolute accuracy for flow and mass transfer in cross-flow hollow fiber membrane artificial lungs is developed. The proposed model is able to predict the gas transfer to water flowing outside and perpendicular to hollow fibers in the artificial lung. The model uses a finite element technique to solve the Navier-Stokes equations and the convection-diffusion equation on the computational domain of a unit fiber cell. Subsequent stream-wise and cross-wise unit fiber cells are then coupled/assembled to the relationship between the oxygen transfer rate and flow rate of a cross-flow hollow fiber membrane artificial lung. The model is compared to experimental water data obtained by perfusing three commercial artificial lungs with water.

Artificial Organs↗