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At least 73 records · Page 4Linked to original sources
PubMed2007

Differential tissue-on-tissue lubrication by ophthalmic formulations.

Tissue-on-tissue friction testing was used to determine how instillation of hydrophilic polymer-containing formulations between the "blinking" tissues would compare with lubrication by saline, alone, or an oil-emulsion preparation. Best results were obtained for a formulation that contained active demulcents polyethylene glycol (PEG 400) and propylene glycol (PG), as well as a gellable polymer hydroxypropyl guar (HP-Guar) in a borate-buffered solution, in comparison with hydroxypropylcellulose-containing and carboxymethylcellulose-containing formulations. Superior performance of all the formulations was found for lubricating tissue-on-tissue couples, compared with metal-oxide-to-metal oxide interfaces, or metal oxide-to-tissue interfaces. A reciprocating pin-on-disc type friction/wear test device articulated the intimal faces of preserved human umbilical cord vein segments under increasing loads during simulated continuous "eye-blinking" with addition of increasing weights up to 60 g/cm2, simulating maximal eyelid force on the orbital globe. The tissue-on-tissue couples moved from liquid phase lubrication to boundary lubrication. After residual formulations were rinsed away with saline, persistence of low friction at the highest loads was indicative of formulation substantivity. Human umbilical cord vein segments were utilized in saline-wetted tissue-on-tissue couples that showed variable starting coefficients of friction in the range 0.2-0.4, producing moderate tearing and disruption of the interfacial layers above the medial collagen zone. The best-performing formulations instilled to the tissues pre-wetted with saline apparently reacted separately with each tissue face to produce a lower final and persistent coefficient of friction of about 0.05. Scanning electron microscopy and light microscopy of these guar-modified tissue specimens showed only a few superficial tissue disruptions, and some interphase swelling consistent with polymer uptake. The frictional values for lubricated couples having non-tissue members were considerably higher than the coefficients of friction measured for the similarly lubricated tissue-on-tissue couples, emphasizing the requirement that appropriate simulations are critical to obtaining clinically predictive data.

Cornea↗
PubMed1997

Tissue inhibitor of metalloproteinase-1 and tissue inhibitor of metalloproteinase-2 expression in human amnion mesenchymal and epithelial cells.

OBJECTIVE: This study was conducted to define the cellular site of expression of tissue inhibitor of metalloproteinase-1 and tissue inhibitor of metalloproteinase-2 in human amnion by an evaluation of the levels of messenger ribonucleic acids in separated amnion epithelial and mesenchymal cells and to ascertain whether amnion epithelial and mesenchymal cells maintained in culture continue to express tissue inhibitor of metalloproteinase messenger ribonucleic acids. STUDY DESIGN: Human placentas and fetal membranes were obtained immediately after delivery. Amnion tissue was separated from chorion laeve and either frozen immediately (-80 degrees C) or processed by differential enzymatic treatment to separate the epithelial and mesenchymal cells, which were frozen (-80 degrees C) or else plated and maintained in monolayer culture. The levels of tissue inhibitor of metalloproteinase types 1 and 2 messenger ribonucleic acid were evaluated by Northern analyses of total ribonucleic acid extracted from amnion tissue, freshly separated epithelial and mesenchymal cells, and epithelial and mesenchymal cells in monolayer culture. RESULTS: Tissue inhibitor of metalloproteinase types 1 and 2 messenger ribonucleic acids were detected by Northern analysis in freshly isolated amnion tissues from midtrimester and term pregnancies. The major species of tissue inhibitor of metalloproteinase-1 messenger ribonucleic acid was 0.9 kb in length; a minor species of approximately 3.5 kb also was present. Tissue inhibitor of metalloproteinase-2 messenger ribonucleic acids of 3.5 and 1.0 kb and of similar intensity were also detected. The levels of type 1 messenger ribonucleic acid were not different in amnion tissues obtained at term or during the midtrimester of pregnancy. The levels of tissue inhibitor of metalloproteinase type 2 messenger ribonucleic acids in amnion tissue most commonly were greater at term than in tissues obtained during the midtrimester. The level of type 1 messenger ribonucleic acid in mesenchymal cells was appreciably greater than that in epithelial cells, and this difference was maintained during culture of these cells. The level of type 2 messenger ribonucleic acid was similar in both cell types and was maintained during culture. The levels of type 1 or 2 messenger ribonucleic acids were not affected by treatment of amnion epithelial or mesenchymal cells in culture with a variety of test agents, including steroid hormones, cytokines, and growth factors. CONCLUSION: The amnion mesenchymal cells are the primary source of tissue inhibitor of metalloproteinase-1 in human amnion, whereas both cell types have the potential to produce tissue inhibitor of metalloproteinase-2.

Amnion↗
PubMed2003

Tissue specific expression and serum levels of human tissue factor in patients with urological cancer.

Human tissue factor (TF) is involved in tumor angiogenesis and metastasis. However, little is known about the distribution of TF in urological cancer. In this study we investigated the TF expression in tumor tissue and autologous non-malignant tissue as well as in serum of patients with renal cell carcinoma (RCC), bladder cancer, and prostate cancer (PCa). To study the distribution of TF in tumor tissue and in the surrounding non-malignant tissue, we measured TF protein by ELISA in tissue specimens obtained intraoperatively from 18 RCC, seven bladder cancer and six PCa patients. Differences in TF expression were found between tumor tissue and nonmalignant tissue for the three tumor types at the protein level (in the order RCC < bladder cancer < PCa). In all but one of the 18 RCC patients (94 %) higher TF protein level was observed in non-malignant tissue as compared to the tumor tissue. In addition, the relative TF mRNA expression analyzed by a quantitative RT-PCR assay in the same RCC tissue sample pairs was higher in 78% of non-malignant tissues in comparison to the tumor tissue specimens. Moreover, using enzyme linked immunosorbent assay the TF protein content was measured in serum samples of 66 patients with bladder cancer, 75 RCC patients and 157 PCa patients, and was compared with the TF serum level of 92 healthy volunteers. Whereas no differences were detected between normal volunteers and patients with PCa or RCC, patients with bladder cancer showed a significantly increased level of serum TF (P=0.0076). However, no causal association between TF levels in serum and TF content in tissue extracts for all three tumor types of urological tumors was found. Our results suggest that TF in non-malignant renal tissues was expressed at a higher level compared to the supposed de novo TF expression in RCC tissue specimens. This indicates a tumor-associated induction of TF expression in the TF-negative RCC progenitor cells. The increased serum TF levels are alike the reported higher urinary TF levels found in bladder cancer patients. The potential clinical relevance of this finding should be further elucidated.

Carcinoma, Renal Cell↗
PubMed2001

Concentration of vascular endothelial growth factor in the tumour tissue as a prognostic factor of soft tissue sarcomas.

Previous studies have shown that the prognosis of patients who have tumours with high microvessel density (MVD) is worse than that of patients who have a lower density in a variety of cancers. In this study, we investigated the clinical relevance of neovascularity assessed by MVD and the concentration of vascular endothelial growth factor (VEGF) in the tumour tissue of patients with soft tissue sarcoma in comparison with major clinicohistologic parameters by univariate and multivariate analysis. In 115 patients with soft tissue sarcoma, MVD was measured by counting vessels stained with factor VIII antibody. The concentration of VEGF in the tumour tissue was determined by enzyme-linked immunosorbent assay. These parameters were then compared with disease outcome. The concentration of VEGF in the tumour tissue, but not MVD, was found to be correlated with disease outcome in patients with soft tissue, sarcoma. VEGF concentration in the tumour tissue showed a relationship with the clinical stage and histologic grade of the tumour. There was no significant difference in the levels of tissue VEGF concentration and MVD among soft tissue sarcomas classified according to histologic type. The level of tissue VEGF concentration in patients who had subsequent local recurrence and metastasis were significantly higher than the respective values in patients who did not have such disease outcome. No significant correlation existed between MVD and the concentration of VEGF in the tumour tissue. Univariate analysis showed that a high tissue VEGF concentration was associated with poor overall survival of the patient and a greater probability that local recurrence and metastasis had occurred. Multivariate analysis revealed that the tissue concentration of VEGF is an independent prognostic factor for the disease outcome of patients with soft tissue sarcoma. VEGF concentration in the tumour tissue, but not MVD, is an additional prognostic parameter for disease outcome in patients with soft tissue sarcoma, regardless of histologic type.

Adult↗
PubMedDate not supplied

Assessment of tissue ingrowth rates in polyurethane scaffolds for tissue engineering.

The continuous development of new biomaterials for tissue engineering and the enhancement of tissue ingrowth into existing scaffolds, using growth factors, create the necessity for developing adequate tools to assess tissue ingrowth rates into porous biomaterials. Current histomorphometric techniques evaluating rates of tissue ingrowth tend either to measure the overall tissue content in an entire sample or to depend on the user to indicate a front of tissue ingrowth. Neither method is particularly suitable for the assessment of tissue ingrowth rates, as these methods either lack the sensitivity required or are problematic when there is a tissue ingrowth gradient rather than an obvious tissue ingrowth front. This study describes a histomorphometric method that requires little observer input, is sensitive, and renders detailed information for the assessment of tissue ingrowth rates into porous biomaterials. This is achieved by examining a number of computer-defined concentric zones, which are based on the distance of a pixel from the scaffold edge. Each zone is automatically analyzed for tissue content, eliminating the need for user definition of a tissue ingrowth front and thus reducing errors and observer dependence. Tissue ingrowth rates in two biodegradable polyurethane scaffolds (Estane and polycaprolactone-polyurethane [PCLPU]) specifically designed for tissue engineering of the knee meniscus were assessed. Samples were subcutaneously implanted in rats with follow-up until 6 months. Especially at the earlier follow-up points, PCLPU scaffolds showed significantly higher tissue ingrowth rates than Estane scaffolds, making the PCLPU scaffold a promising candidate for further studies investigating meniscus tissue engineering.

Animals↗
PubMed1999

Tissue factor de-encryption: ionophore treatment induces changes in tissue factor activity by phosphatidylserine-dependent and -independent mechanisms.

Coagulation is initiated on tissue-factor-bearing cells when factor VIIa complexes with membrane-bound tissue factor and activates factors X and IX. Cellular tissue factor activity does not correlate with tissue factor antigen; treatment with calcium ionophore rapidly increases tissue factor activity without increasing tissue factor antigen. Our study examined the effect of calcium ionophore A23187 on tissue factor activity of freshly isolated, lipopolysaccharide-stimulated monocytes and non-transformed human dermal fibroblasts. A23187 increased tissue factor activity on monocytes and fibroblasts in a dose-dependent fashion between 0.1 and 50 micromol/l ionophore. This increase in activity was proportional to an increase in intracellular calcium in monocytes. The increase in tissue factor activity was partially attributable to an increase in phosphatidylserine expression, as measured by increased prothrombinase activity (1.1- to 4-fold) on ionophore-treated cells. The phosphatidylserine-binding protein annexin V decreased tissue factor activity on both ionophore-treated and untreated cells, reflecting the role of phosphatidylserine in tissue factor activity. However, even in the presence of saturating concentrations of annexin V, the tissue factor activity of ionophore-treated cells was 1.3- to 11.3-fold higher than that of untreated cells, indicating that the increase in tissue factor activity did not result solely from increased expression of phosphatidylserine. A23187 increased tissue-factor-dependent activation of factors IX and X 1.4- to 7-fold on both cell types, indicating that ionophore treatment did not alter factor VIIa/tissue factor substrate specificity. We conclude that the mechanism by which calcium ionophore increases tissue factor activity is not unique to monocytoid or transformed cells. Furthermore, the ionophore-induced increase in activity is not solely the result of increased exposure to phosphatidylserine. Finally, tissue factor de-encryption by A23187 does not alter factor VIIa/tissue factor substrate specificity.

Calcimycin↗
PubMed2002

Tissue solubility of four volatile anesthetics in fresh and frozen tissue specimens from swine.

OBJECTIVE: To determine tissue solubilities of desflurane, sevoflurane, enflurane, and halothane in swine and to evaluate the effects of freezing specimens on tissue solubility, SAMPLE POPULATION: Arterial blood samples and specimens of brain, heart, liver, kidney, muscle, and subcutaneous fat from 5 healthy female adult Chinese Meishan pigs. PROCEDURE: Each tissue specimen was divided into 2 parts. One part was used to measure tissue-gas partition coefficients immediately after collection. The other part was frozen at -20 C for 6 days prior to determination of tissue-gas partition coefficients. Tissue-gas and blood-gas partition coefficients were measured by use of gas chromatography, and tissue-blood partition coefficients were calculated. Regression analysis was performed to determine whether fat-gas partition coefficients were correlated with lean tissue-gas partition coefficients. RESULTS: Tissue-gas and blood-gas partition coefficients of halothane were greater than those of enflurane followed by coefficients of sevoflurane and desflurane. However, the order of anesthetic agents with the greatest to smallest tissue-blood partition coefficients was sevoflurane, halothane, enflurane, and desflurane. Muscle-gas partition coefficients of sevoflurane and enflurane, liver-gas partition coefficients of desflurane and halothane, and the kidney-gas partition coefficient of enflurane were significantly greater in frozen specimens, compared with fresh specimens. Lean tissue-gas partition coefficients of all 4 volatile anesthetics correlated directly with fat-gas partition coefficients. CONCLUSIONS AND CLINICAL RELEVANCE: The fat content of lean tissue is an important factor in determining the tissue solubility of volatile anesthetics. Freezing specimens before determination of tissue-gas partition coefficients may result in a false increase in tissue solubility.

Adipose Tissue↗
PubMed2000

Infrared spectroscopy of human cells and tissue. VIII. Strategies for analysis of infrared tissue mapping data and applications to liver tissue.

Experimental and computational methods of infrared microspectroscopy (IRI-MSP) and infrared spectral mapping (ISM) are presented. These methods are subsequently applied to the analysis of cirrhotic liver tissue. The sensitivity of infrared spectral mapping toward spectral changes caused by disease will be demonstrated. In addition, the excellent agreement between ISM data and histopathological information will be discussed.

Humans↗
PubMed2006

Color tissue Doppler myocardial velocities consistently underestimate spectral tissue Doppler velocities: impact on calculation peak transmitral pulsed Doppler velocity/early diastolic tissue Doppler velocity (E/Ea).

BACKGROUND: Color tissue Doppler (TD) measures mean myocardial velocities, whereas spectral TD measures peak velocities. Given that most data on left ventricular (LV) diastolic function used spectral TD, we investigated whether the differences in myocardial velocities between these modalities resulted in discrepancies in calculated E/Ea. METHODS: Patients were imaged using an ultrasound machine. The systolic (Sa), early diastolic (Ea), and late diastolic (Aa) myocardial velocities by color and spectral TD were measured at basal and midsegments of the LV septal, lateral, inferior, and anterior walls in the apical views. The average of basal septal and lateral Ea was combined with the early transmitral diastolic velocity (E) to obtain E/Ea. RESULTS: In all, 31 patients were imaged, with a mean LV ejection fraction of 47.7% +/- 19.9. There were significant correlations between Sa, Ea, and Aa by color and spectral TD at all sites (R = 0.92, P < .001 for Ea at basal lateral wall) and between spectral and color E/Ea (R = 0.85, P < .001). Sa, Ea, and Aa were significantly lower by color TD than by spectral TD (basal septal color Ea = 3.0 +/- 2.0 cm/s vs 5.6 +/- 2.5 cm/s for spectral Ea, P < .001). Consequently, E/Ea by color TD was significantly higher than by spectral TD (22.3 +/- 15.3 vs 13.6 +/- 7.8, P < .001). CONCLUSIONS: Although significant correlations exist, myocardial velocities measured using color TD significantly underestimate velocities by spectral TD. Consequently, E/Ea by color TD significantly overestimates E/Ea using spectral TD, which could lead to errors in assessment of LV diastolic function.

Artifacts↗
PubMed2004

Tissue engineered nucleus pulposus tissue formed on a porous calcium polyphosphate substrate.

STUDY DESIGN: This study describes the formation of nucleus pulposus tissue using a novel tissue engineering approach. OBJECTIVES: To determine if a construct composed of nucleus pulposus tissue on the surface of a calcium polyphosphate substrate could be formed in vitro with properties similar to native nucleus pulposus tissue. SUMMARY OF BACKGROUND DATA: There is no optimal treatment for the persistent pain associated with intervertebral disc degeneration. Disc replacement using artificial intervertebral discs has met with some success, and biologic transplantation is limited by the availability of donor tissues. METHODS: Nucleus pulposus cells were isolated from bovine caudal intervertebral discs. Cells were seeded at high density on the upper surface of a porous bone substitute material (calcium polyphosphate) and maintained up to 6 weeks in culture. In vitro formed tissue was compared to native nucleus pulposus for histologic appearance, biochemical composition (tissue cellularity, proteoglycan and collagen accumulation), and compressive mechanical properties. RESULTS: When maintained on the surface of a three-dimensional substrate, nucleus pulposus cells formed a continuous layer of tissue with a proteoglycan content equivalent to the native tissue. Although collagen accumulation attained only 26% than that of the native tissue, there was no difference in tissue stiffness, viscosity, or weight-bearing capacity of the in vitro formed tissue when compared with the native tissue. CONCLUSION: Nucleus pulposus-like tissue formed in vitro on the surface of a calcium polyphosphate substrate resembles the native tissue in terms of proteoglycan content and compressive mechanical properties. These studies are the first step toward developing a functional spinal unit in vitro.

Animals↗
PubMed2004

Tissue pharmacokinetics of levofloxacin in human soft tissue infections.

AIMS: The present study addressed the ability of levofloxacin to penetrate into subcutaneous adipose tissues in patients with soft tissue infection. METHODS: Tissue concentrations of levofloxacin in inflamed and healthy subcutaneous adipose tissue were measured in six patients by microdialysis after administration of a single intravenous dose of 500 mg. Levofloxacin was assayed by high-performance liquid chromatography. RESULTS: The mean concentration vs time profile of free levofloxacin in plasma was identical to that in inflamed and healthy tissues. The ratios of the mean area under the free levofloxacin concentration vs time curve from 0 to 10 h (AUC(0,10 h)) in tissue to that in plasma were 1.2 +/- 1.0 for inflamed and 1.1 +/- 0.6 for healthy subcutaneous adipose tissue (mean +/- SD). The mean difference in the ratio of the AUC(tissue) : AUC(plasma) for inflamed and healthy tissue was 0.09 (95% confidence interval -0.58, 0.759, P > 0.05). Interindividual variability in tissue penetration was high, as indicated by a coefficient of variation of approximately 82% for AUC(tissue) : AUC(plasma) ratios. CONCLUSIONS: The penetration of levofloxacin into tissue appears to be unaffected by local inflammation. Our plasma and tissue data suggest that an intravenous dose of 500 mg levofloxacin provides effective antibacterial concentrations at the target site. However, in treatment resistant patients, tissue concentrations may be sub-therapeutic.

Adipose Tissue↗
PubMed1987

Sodium and potassium saturation kinetics of Na+K+-ATPase in plasma membranes from corneal endothelium: fresh tissue vs. tissue culture.

The maximal velocity (Vmax) and the apparent dissociation constant (K0.5) of Na+K+-ATPase have each been estimated with respect to sodium and potassium ion activation. These estimations were made from the enzymatic activity of plasma membrane preparations derived from bovine corneal endothelial cells. The determinations were made on cells obtained from fresh tissue and from secondary tissue cultures. Two methods were used to obtain the estimates: the first used a combination of Eadie-Hofstee and Hill plots; the second used Eisenthal-Cornish-Bowden plots. The Vmax for sodium was 5.58-5.60 mumol Pi/mg protein/30 min for fresh tissue vs. 2.00-1.80 mumoles Pi/mg protein/30 min for tissue cultures. The corresponding K0.5 values were 62-57 mM (fresh tissue) vs. 7.9-6.7 mM (tissue culture). Vmax for potassium was 4.28-4.00 mumoles Pi/mg protein/30 min for fresh tissue vs. 1.37-1.34 mumoles Pi/mg protein/30 min for tissue cultures. The corresponding K0.5 values were 3.3-3.1 mM (fresh tissue) and 1.7-1.7 mM (tissue culture). The results indicate a lowered activity and change in affinity of the enzyme for the two ions in tissue cultures compared to fresh tissues. The detergent Lubrol W-X increased activity in both tissue sources. Sonication had no significant effect on the activity. Variations in pH (7-9) indicated that the highest activity was obtained at pH 7.8 for the enzyme in tissue culture while activity was highest at pH 8.0 for the enzyme in fresh tissues. These differences in kinetic activity suggest a response to changes in the ion requirements of these cells due to their environment, developmental stage or some other parameter.

Animals↗
PubMed2005

Expression of albumin, IGF-1, IGFBP-3 in tumor tissues and adjacent non-tumor tissues of hepatocellular carcinoma patients with cirrhosis.

AIM: To explore the expression of albumin (ALB), insulin-like growth factor (IGF)-1, and insulin-like growth factor binding protein (IGFBP)-3 in tumor tissues and adjacent non-tumor tissues of hepatocellular carcinoma (HCC) patients with cirrhosis. METHODS: Twenty-four HCC patients with cirrhosis who underwent hepatectomy were studied. ALB mRNA, IGF-1 mRNA, and IGFBP-3 mRNA in liver tissues (including tumor tissues and adjacent non-tumor tissues) were detected by reverse transcriptase-polymerase chain reaction (RT-PCR). Liver Ki67 immunohistochemistry staining was studied. At the same time, 12 patients with cholelithiasis or liver angioma who underwent operation were segregated as normal control. RESULTS: In HCC patients with cirrhosis, hepatic ALB mRNA, IGF-1 mRNA, and IGFBP-3 mRNA of tumor tissues or adjacent non-tumor tissues were lower than the normal liver tissues, while in tumor tissues, hepatic ALB mRNA and IGFBP-3 mRNA were lower, hepatic IGF-1 mRNA was higher than in adjacent non-tumor tissues. Liver Ki67 labeling index (Ki67 LI) in tumor tissues or adjacent non-tumor tissues were higher than that in the normal liver tissues, while in tumor tissues it was higher than that in adjacent non-tumor tissues. CONCLUSION: Imbalance of IGF-1 and IGFBP-3 may play a role in hepatocarcinogenesis and tumor development of liver cirrhosis patients.

Albumins↗
PubMed2002

The suitability of cells from different tissues for use in tissue-engineered skin substitutes.

Tissue-engineered skin substitutes may be a future remedy for burn wounds and chronic wounds, as wound contraction and scar formation cannot be prevented with the current standard treatment. The aim of this study therefore was to identify readily available sources of fibroblasts suitable for dermal substitution. Three different tissues were studied: dermal tissue from split-skin graft, subcutaneous fat tissue and eschar tissue obtained through debridement of burn wounds. We determined the cellular profile and the cell numbers immediately after isolation and after 2 and 14 days of fibroblast culture using flow cytometry and cell counting with a cytometer. In addition, parts of the isolated cell suspensions were seeded directly into a porous collagen dermal substitute to investigate contraction over time. Various cell types were isolated from the three different tissues, but after 14 days of culturing predominantly fibroblasts (>90%) were detected. Keratinocytes, granulocytes and macrophages, if present, disappeared within 14 days. In the cell populations derived from dermal tissue, the percentage of myofibroblasts had decreased significantly by day 14 (from 8% to 3%, P=0.028). In contrast, this percentage had increased in the cell populations derived from fat and eschar (from 23% to 40% and from 20% to 38%, respectively). The fibroblast yield from dermal tissue after 2 weeks of culturing (50 x 10(6) cells/g of tissue) was significantly higher than the yield from fat and eschar tissue (2 x 10(6) cells/g of each tissue, P=0.029). Immunohistochemistry of collagen matrices seeded and cultured with fat- and eschar-derived cells revealed a high prevalence of myofibroblasts, whereas hardly any myofibroblasts were detected in the matrices seeded with dermal cells. The contraction of the eschar matrices was highest (74+/-6% remaining area), whereas dermal matrices contracted significantly less (92+/-7% remaining area, P=0.029) with intermediate contraction for fat matrices. We conclude that fibroblast cultures can be established from dermal tissue, fat tissue and eschar tissue. Dermis is the best fibroblast source for use in skin substitutes as it yields the highest numbers of fibroblasts with minimal numbers of myofibroblasts.

Adipose Tissue↗
PubMed2006

Diffusion of bioactive molecules through the walls of the medial tissue-engineered hybrid ePTFE grafts for applications in designs of vascular tissue regeneration.

Strategies of better vascular tissue engineering may require delivery of soluble bioactive signals in cell culture medium to the cells in tissue-regenerating constructs. We measured the diffusivity and permeability of model tissue-engineering bioactive molecules such as water and heparin through the walls of both a hybrid ePTFE graft and a porcine carotid artery, a model vascular tissue. While diffusivities of H(3)-water and H(3)-heparin were measured as 3.9 x 10(-) (6) and 1.6 x 10(-) (6) cm(2)/s in the artery, respectively, under diffusional circulation of cell culture medium through the lumens of the carotid arteries, their corresponding permeabilities were 4.7 x 10(-) (5) and 2.0 x 10(-) (5) cm/s. On the other hand, diffusivities of H(3)-water and H(3)-heparin were also measured as 5.1 x 10(-) (6) and 4.7 x 10(-) (6) cm(2)/s, respectively, in the tissue-engineered hybrid ePTFE grafts; their corresponding permeabilities were 5.1 x 10(-) (5) and 3.7 x 10(-) (5) cm/s. The hybrid graft tissues were engineered by replacing the biodegradable, porous poly(lactide-co-glycolide) layers coated on the ePTFE surfaces with smooth muscle cell-derived tissues for 6 weeks. We analyzed the morphologies of the artery and the engineered hybrid ePTFE tissues with scanning electron microscopy and H&E stains. While the artery had its typical structure properties with layers of intima, media and adventitia, the tissue-engineered ePTFE hybrid graft had two layers of engineered tissues on the inner and outer surfaces of the ePTFE. There were no significant differences among the luminal tissue morphologies of the test samples from the effects of diffusion flow applications, with minor changes on their luminal surfaces. The results of water and heparin diffusion experiments indicated that these bioactive molecules were well transported from the cell culture medium to the tissue-engineering cells, enough to support tissue regeneration. We hope that these transport results may elucidate the transport behaviors of soluble nutrient molecules and biological signals through the vascular constructs under tissue engineering processes.

Absorbable Implants↗
PubMed2005

Differences in gene expression in prostate cancer, normal appearing prostate tissue adjacent to cancer and prostate tissue from cancer free organ donors.

BACKGROUND: Typical high throughput microarrays experiments compare gene expression across two specimen classes - an experimental class and baseline (or comparison) class. The choice of specimen classes is a major factor in the differential gene expression patterns revealed by these experiments. In most studies of prostate cancer, histologically malignant tissue is chosen as the experimental class while normal appearing prostate tissue adjacent to the tumor (adjacent normal) is chosen as the baseline against which comparison is made. However, normal appearing prostate tissue from tumor free organ donors represents an alterative source of baseline tissue for differential expression studies. METHODS: To examine the effect of using donor normal tissue as opposed to adjacent normal tissue as a baseline for prostate cancer expression studies, we compared, using oligonucleotide microarrays, the expression profiles of primary prostate cancer (tumor), adjacent normal tissue and normal tissue from tumor free donors. RESULTS: Statistical analysis using Significance Analysis of Microarrays (SAM) demonstrates the presence of unique gene expression profiles for each of these specimen classes. The tumor v donor expression profile was more extensive that the tumor v adjacent normal profile. The differentially expressed gene lists from tumor v donor, tumor v adjacent normal and adjacent normal v donor comparisons were examined to identify regulated genes. When donors were used as the baseline, similar genes are highly regulated in both tumor and adjacent normal tissue. Significantly, both tumor and adjacent normal tissue exhibit significant up regulation of proliferation related genes including transcription factors, signal transducers and growth regulators compared to donor tissue. These genes were not picked up in a direct comparison of tumor and adjacent normal tissues. CONCLUSIONS: The up-regulation of these gene types in both tissue types is an unexpected finding and suggests that normal appearing prostate tissue can undergo genetic changes in response to or in expectation of morphologic cancer. A possible field effect surrounding prostate cancers and the implications of these findings for characterizing gene expression changes in prostate tumors are discussed.

Adult↗
PubMed2002

[Comparison of ultrastructural changes of skin between continuous tissue expansion and conventional tissue expansion].

OBJECTIVE: To observe the ultrastrual changes of the skin between the continuous tissue expansion and the conventional tissue expansion. METHODS: Twelve white piglets were used for this study on an animal model of tissue expansion with the continuous tissue expansion group and the conventional tissue expansion group. The tissue samples in each group were harvested and prepared for the transmission electron microscope observation. RESULTS: The interspace among basal cells and spinose cells was increasing and the numbers of cell conjunctures were decreasing in the both groups. However, these changes in the continuous tissue expansion group were more obvious than in the conventional tissue expansion group. In the dermal layer of the skin, the ultrastructure of collagen fibers were basically normal. But, the fibroblasts and capillary endothelia cells were more activated in the continuous tissue expansion group, compared with the conventional tissue expansion group. The fibroblast apoptosis and collagenolysis spots were observed in both of the groups, while the red blood cells were also found in the tissue leaked outsides from the blood vascular cavities. CONCLUSION: Tissue expansion may result in tissue growth and tissue degeneration in the same time.

Animals↗